code:
# -*- coding: utf-8; mode: python -*-
# pylint: disable=C0103, R0903, R0912, R0915
u"""
    scalable figure and image handling
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    Sphinx extension which implements scalable image handling.

    :copyright:  Copyright (C) 2016  Markus Heiser
    :license:    GPL Version 2, June 1991 see Linux/COPYING for details.

    The build for image formats depend on image's source format and output's
    destination format. This extension implement methods to simplify image
    handling from the author's POV. Directives like ``kernel-figure`` implement
    methods *to* always get the best output-format even if some tools are not
    installed. For more details take a look at ``convert_image(...)`` which is
    the core of all conversions.

    * ``.. kernel-image``: for image handling / a ``.. image::`` replacement

    * ``.. kernel-figure``: for figure handling / a ``.. figure::`` replacement

    * ``.. kernel-render``: for render markup / a concept to embed *render*
      markups (or languages). Supported markups (see ``RENDER_MARKUP_EXT``)

      - ``DOT``: render embedded Graphviz's **DOC**
      - ``SVG``: render embedded Scalable Vector Graphics (**SVG**)
      - ... *developable*

    Used tools:

    * ``dot(1)``: Graphviz (https://www.graphviz.org). If Graphviz is not
      available, the DOT language is inserted as literal-block.
      For conversion to PDF, ``rsvg-convert(1)`` of librsvg
      (https://gitlab.gnome.org/GNOME/librsvg) is used when available.

    * SVG to PDF: To generate PDF, you need at least one of this tools:

      - ``convert(1)``: ImageMagick (https://www.imagemagick.org)
      - ``inkscape(1)``: Inkscape (https://inkscape.org/)

    List of customizations:

    * generate PDF from SVG / used by PDF (LaTeX) builder

    * generate SVG (html-builder) and PDF (latex-builder) from DOT files.
      DOT: see https://www.graphviz.org/content/dot-language

    """

import os
from os import path
import subprocess
from hashlib import sha1
import re
from docutils import nodes
from docutils.statemachine import ViewList
from docutils.parsers.rst import directives
from docutils.parsers.rst.directives import images
import sphinx
from sphinx.util.nodes import clean_astext
import kernellog

# Get Sphinx version
major, minor, patch = sphinx.version_info[:3]
if major == 1 and minor > 3:
    # patches.Figure only landed in Sphinx 1.4
    from sphinx.directives.patches import Figure  # pylint: disable=C0413
else:
    Figure = images.Figure

__version__  = '1.0.0'

# simple helper
# -------------

def which(cmd):
    """Searches the ``cmd`` in the ``PATH`` environment.

    This *which* searches the PATH for executable ``cmd`` . First match is
    returned, if nothing is found, ``None` is returned.
    """
    envpath = os.environ.get('PATH', None) or os.defpath
    for folder in envpath.split(os.pathsep):
        fname = folder + os.sep + cmd
        if path.isfile(fname):
            return fname

def mkdir(folder, mode=0o775):
    if not path.isdir(folder):
        os.makedirs(folder, mode)

def file2literal(fname):
    with open(fname, "r") as src:
        data = src.read()
        node = nodes.literal_block(data, data)
    return node

def isNewer(path1, path2):
    """Returns True if ``path1`` is newer than ``path2``

    If ``path1`` exists and is newer than ``path2`` the function returns
    ``True`` is returned otherwise ``False``
    """
    return (path.exists(path1)
            and os.stat(path1).st_ctime > os.stat(path2).st_ctime)

def pass_handle(self, node):           # pylint: disable=W0613
    pass

# setup conversion tools and sphinx extension
# -------------------------------------------

# Graphviz's dot(1) support
dot_cmd = None
# dot(1) -Tpdf should be used
dot_Tpdf = False

# ImageMagick' convert(1) support
convert_cmd = None

# librsvg's rsvg-convert(1) support
rsvg_convert_cmd = None

# Inkscape's inkscape(1) support
inkscape_cmd = None
# Inkscape prior to 1.0 uses different command options
inkscape_ver_one = False

def setup(app):
    # check toolchain first
    app.connect('builder-inited', setupTools)

    # image handling
    app.add_directive("kernel-image",  KernelImage)
    app.add_node(kernel_image,
                 html    = (visit_kernel_image, pass_handle),
                 latex   = (visit_kernel_image, pass_handle),
                 texinfo = (visit_kernel_image, pass_handle),
                 text    = (visit_kernel_image, pass_handle),
                 man     = (visit_kernel_image, pass_handle), )

    # figure handling
    app.add_directive("kernel-figure", KernelFigure)
    app.add_node(kernel_figure,
                 html    = (visit_kernel_figure, pass_handle),
                 latex   = (visit_kernel_figure, pass_handle),
                 texinfo = (visit_kernel_figure, pass_handle),
                 text    = (visit_kernel_figure, pass_handle),
                 man     = (visit_kernel_figure, pass_handle), )

    # render handling
    app.add_directive('kernel-render', KernelRender)
    app.add_node(kernel_render,
                 html    = (visit_kernel_render, pass_handle),
                 latex   = (visit_kernel_render, pass_handle),
                 texinfo = (visit_kernel_render, pass_handle),
                 text    = (visit_kernel_render, pass_handle),
                 man     = (visit_kernel_render, pass_handle), )

    app.connect('doctree-read', add_kernel_figure_to_std_domain)

    return dict(
        version = __version__,
        parallel_read_safe = True,
        parallel_write_safe = True
    )

def setupTools(app):
    u"""
    Check available build tools and log some *verbose* messages.

    This function is called once, when the builder is initiated.
    """
    global dot_cmd, dot_Tpdf, convert_cmd, rsvg_convert_cmd   # pylint: disable=W0603
    global inkscape_cmd, inkscape_ver_one  # pylint: disable=W0603
    kernellog.verbose(app, "kfigure: check installed tools ...")

    dot_cmd = which('dot')
    convert_cmd = which('convert')
    rsvg_convert_cmd = which('rsvg-convert')
    inkscape_cmd = which('inkscape')

    if dot_cmd:
        kernellog.verbose(app, "use dot(1) from: " + dot_cmd)

        try:
            dot_Thelp_list = subprocess.check_output([dot_cmd, '-Thelp'],
                                    stderr=subprocess.STDOUT)
        except subprocess.CalledProcessError as err:
            dot_Thelp_list = err.output
            pass

        dot_Tpdf_ptn = b'pdf'
        dot_Tpdf = re.search(dot_Tpdf_ptn, dot_Thelp_list)
    else:
        kernellog.warn(app, "dot(1) not found, for better output quality install "
                       "graphviz from https://www.graphviz.org")
    if inkscape_cmd:
        kernellog.verbose(app, "use inkscape(1) from: " + inkscape_cmd)
        inkscape_ver = subprocess.check_output([inkscape_cmd, '--version'],
                                               stderr=subprocess.DEVNULL)
        ver_one_ptn = b'Inkscape 1'
        inkscape_ver_one = re.search(ver_one_ptn, inkscape_ver)
        convert_cmd = None
        rsvg_convert_cmd = None
        dot_Tpdf = False

    else:
        if convert_cmd:
            kernellog.verbose(app, "use convert(1) from: " + convert_cmd)
        else:
            kernellog.verbose(app,
                "Neither inkscape(1) nor convert(1) found.\n"
                "For SVG to PDF conversion, "
                "install either Inkscape (https://inkscape.org/) (preferred) or\n"
                "ImageMagick (https://www.imagemagick.org)")

        if rsvg_convert_cmd:
            kernellog.verbose(app, "use rsvg-convert(1) from: " + rsvg_convert_cmd)
            kernellog.verbose(app, "use 'dot -Tsvg' and rsvg-convert(1) for DOT -> PDF conversion")
            dot_Tpdf = False
        else:
            kernellog.verbose(app,
                "rsvg-convert(1) not found.\n"
                "  SVG rendering of convert(1) is done by ImageMagick-native renderer.")
            if dot_Tpdf:
                kernellog.verbose(app, "use 'dot -Tpdf' for DOT -> PDF conversion")
            else:
                kernellog.verbose(app, "use 'dot -Tsvg' and convert(1) for DOT -> PDF conversion")

# integrate conversion tools
# --------------------------

RENDER_MARKUP_EXT = {
    # The '.ext' must be handled by convert_image(..) function's *in_ext* input.
    # <name> : <.ext>
    'DOT' : '.dot',
    'SVG' : '.svg'
}

def convert_image(img_node, translator, src_fname=None):
    """Convert a image node for the builder.

    Different builder prefer different image formats, e.g. *latex* builder
    prefer PDF while *html* builder prefer SVG format for images.

    This function handles output image formats in dependence of source the
    format (of the image) and the translator's output format.
    """
    app = translator.builder.app

    fname, in_ext = path.splitext(path.basename(img_node['uri']))
    if src_fname is None:
        src_fname = path.join(translator.builder.srcdir, img_node['uri'])
        if not path.exists(src_fname):
            src_fname = path.join(translator.builder.outdir, img_node['uri'])

    dst_fname = None

    # in kernel builds, use 'make SPHINXOPTS=-v' to see verbose messages

    kernellog.verbose(app, 'assert best format for: ' + img_node['uri'])

    if in_ext == '.dot':

        if not dot_cmd:
            kernellog.verbose(app,
                              "dot from graphviz not available / include DOT raw.")
            img_node.replace_self(file2literal(src_fname))

        elif translator.builder.format == 'latex':
            dst_fname = path.join(translator.builder.outdir, fname + '.pdf')
            img_node['uri'] = fname + '.pdf'
            img_node['candidates'] = {'*': fname + '.pdf'}

        elif translator.builder.format == 'html':
            dst_fname = path.join(
                translator.builder.outdir,
                translator.builder.imagedir,
                fname + '.svg')
            img_node['uri'] = path.join(
                translator.builder.imgpath, fname + '.svg')
            img_node['candidates'] = {
                '*': path.join(translator.builder.imgpath, fname + '.svg')}

        else:
            # all other builder formats will include DOT as raw
            img_node.replace_self(file2literal(src_fname))

    elif in_ext == '.svg':

        if translator.builder.format == 'latex':
            if not inkscape_cmd and convert_cmd is None:
                kernellog.warn(app,
                                  "no SVG to PDF conversion available / include SVG raw."
                                  "\nIncluding large raw SVGs can cause xelatex error."
                                  "\nInstall Inkscape (preferred) or ImageMagick.")
                img_node.replace_self(file2literal(src_fname))
            else:
                dst_fname = path.join(translator.builder.outdir, fname + '.pdf')
                img_node['uri'] = fname + '.pdf'
                img_node['candidates'] = {'*': fname + '.pdf'}

    if dst_fname:
        # the builder needs not to copy one more time, so pop it if exists.
        translator.builder.images.pop(img_node['uri'], None)
        _name = dst_fname[len(translator.builder.outdir) + 1:]

        if isNewer(dst_fname, src_fname):
            kernellog.verbose(app,
                              "convert: {out}/%s already exists and is newer" % _name)

        else:
            ok = False
            mkdir(path.dirname(dst_fname))

            if in_ext == '.dot':
                kernellog.verbose(app, 'convert DOT to: {out}/' + _name)
                if translator.builder.format == 'latex' and not dot_Tpdf:
                    svg_fname = path.join(translator.builder.outdir, fname + '.svg')
                    ok1 = dot2format(app, src_fname, svg_fname)
                    ok2 = svg2pdf_by_rsvg(app, svg_fname, dst_fname)
                    ok = ok1 and ok2

                else:
                    ok = dot2format(app, src_fname, dst_fname)

            elif in_ext == '.svg':
                kernellog.verbose(app, 'convert SVG to: {out}/' + _name)
                ok = svg2pdf(app, src_fname, dst_fname)

            if not ok:
                img_node.replace_self(file2literal(src_fname))

def dot2format(app, dot_fname, out_fname):
    """Converts DOT file to ``out_fname`` using ``dot(1)``.

    * ``dot_fname`` pathname of the input DOT file, including extension ``.dot``
    * ``out_fname`` pathname of the output file, including format extension

    The *format extension* depends on the ``dot`` command (see ``man dot``
    option ``-Txxx``). Normally you will use one of the following extensions:

    - ``.ps`` for PostScript,
    - ``.svg`` or ``svgz`` for Structured Vector Graphics,
    - ``.fig`` for XFIG graphics and
    - ``.png`` or ``gif`` for common bitmap graphics.

    """
    out_format = path.splitext(out_fname)[1][1:]
    cmd = [dot_cmd, '-T%s' % out_format, dot_fname]
    exit_code = 42

    with open(out_fname, "w") as out:
        exit_code = subprocess.call(cmd, stdout = out)
        if exit_code != 0:
            kernellog.warn(app,
                          "Error #%d when calling: %s" % (exit_code, " ".join(cmd)))
    return bool(exit_code == 0)

def svg2pdf(app, svg_fname, pdf_fname):
    """Converts SVG to PDF with ``inkscape(1)`` or ``convert(1)`` command.

    Uses ``inkscape(1)`` from Inkscape (https://inkscape.org/) or ``convert(1)``
    from ImageMagick (https://www.imagemagick.org) for conversion.
    Returns ``True`` on success and ``False`` if an error occurred.

    * ``svg_fname`` pathname of the input SVG file with extension (``.svg``)
    * ``pdf_name``  pathname of the output PDF file with extension (``.pdf``)

    """
    cmd = [convert_cmd, svg_fname, pdf_fname]
    cmd_name = 'convert(1)'

    if inkscape_cmd:
        cmd_name = 'inkscape(1)'
        if inkscape_ver_one:
            cmd = [inkscape_cmd, '-o', pdf_fname, svg_fname]
        else:
            cmd = [inkscape_cmd, '-z', '--export-pdf=%s' % pdf_fname, svg_fname]

    try:
        warning_msg = subprocess.check_output(cmd, stderr=subprocess.STDOUT)
        exit_code = 0
    except subprocess.CalledProcessError as err:
        warning_msg = err.output
        exit_code = err.returncode
        pass

    if exit_code != 0:
        kernellog.warn(app, "Error #%d when calling: %s" % (exit_code, " ".join(cmd)))
        if warning_msg:
            kernellog.warn(app, "Warning msg from %s: %s"
                           % (cmd_name, str(warning_msg, 'utf-8')))
    elif warning_msg:
        kernellog.verbose(app, "Warning msg from %s (likely harmless):\n%s"
                          % (cmd_name, str(warning_msg, 'utf-8')))

    return bool(exit_code == 0)

def svg2pdf_by_rsvg(app, svg_fname, pdf_fname):
    """Convert SVG to PDF with ``rsvg-convert(1)`` command.

    * ``svg_fname`` pathname of input SVG file, including extension ``.svg``
    * ``pdf_fname`` pathname of output PDF file, including extension ``.pdf``

    Input SVG file should be the one generated by ``dot2format()``.
    SVG -> PDF conversion is done by ``rsvg-convert(1)``.

    If ``rsvg-convert(1)`` is unavailable, fall back to ``svg2pdf()``.

    """

    if rsvg_convert_cmd is None:
        ok = svg2pdf(app, svg_fname, pdf_fname)
    else:
        cmd = [rsvg_convert_cmd, '--format=pdf', '-o', pdf_fname, svg_fname]
        # use stdout and stderr from parent
        exit_code = subprocess.call(cmd)
        if exit_code != 0:
            kernellog.warn(app, "Error #%d when calling: %s" % (exit_code, " ".join(cmd)))
        ok = bool(exit_code == 0)

    return ok

# image handling
# ---------------------

def visit_kernel_image(self, node):    # pylint: disable=W0613
    """Visitor of the ``kernel_image`` Node.

    Handles the ``image`` child-node with the ``convert_image(...)``.
    """
    img_node = node[0]
    convert_image(img_node, self)

class kernel_image(nodes.image):
    """Node for ``kernel-image`` directive."""
    pass

class KernelImage(images.Image):
    u"""KernelImage directive

    Earns everything from ``.. image::`` directive, except *remote URI* and
    *glob* pattern. The KernelImage wraps a image node into a
    kernel_image node. See ``visit_kernel_image``.
    """

    def run(self):
        uri = self.arguments[0]
        if uri.endswith('.*') or uri.find('://') != -1:
            raise self.severe(
                'Error in "%s: %s": glob pattern and remote images are not allowed'
                % (self.name, uri))
        result = images.Image.run(self)
        if len(result) == 2 or isinstance(result[0], nodes.system_message):
            return result
        (image_node,) = result
        # wrap image node into a kernel_image node / see visitors
        node = kernel_image('', image_node)
        return [node]

# figure handling
# ---------------------

def visit_kernel_figure(self, node):   # pylint: disable=W0613
    """Visitor of the ``kernel_figure`` Node.

    Handles the ``image`` child-node with the ``convert_image(...)``.
    """
    img_node = node[0][0]
    convert_image(img_node, self)

class kernel_figure(nodes.figure):
    """Node for ``kernel-figure`` directive."""

class KernelFigure(Figure):
    u"""KernelImage directive

    Earns everything from ``.. figure::`` directive, except *remote URI* and
    *glob* pattern.  The KernelFigure wraps a figure node into a kernel_figure
    node. See ``visit_kernel_figure``.
    """

    def run(self):
        uri = self.arguments[0]
        if uri.endswith('.*') or uri.find('://') != -1:
            raise self.severe(
                'Error in "%s: %s":'
                ' glob pattern and remote images are not allowed'
                % (self.name, uri))
        result = Figure.run(self)
        if len(result) == 2 or isinstance(result[0], nodes.system_message):
            return result
        (figure_node,) = result
        # wrap figure node into a kernel_figure node / see visitors
        node = kernel_figure('', figure_node)
        return [node]

# render handling
# ---------------------

def visit_kernel_render(self, node):
    """Visitor of the ``kernel_render`` Node.

    If rendering tools available, save the markup of the ``literal_block`` child
    node into a file and replace the ``literal_block`` node with a new created
    ``image`` node, pointing to the saved markup file. Afterwards, handle the
    image child-node with the ``convert_image(...)``.
    """
    app = self.builder.app
    srclang = node.get('srclang')

    kernellog.verbose(app, 'visit kernel-render node lang: "%s"' % (srclang))

    tmp_ext = RENDER_MARKUP_EXT.get(srclang, None)
    if tmp_ext is None:
        kernellog.warn(app, 'kernel-render: "%s" unknown / include raw.' % (srclang))
        return

    if not dot_cmd and tmp_ext == '.dot':
        kernellog.verbose(app, "dot from graphviz not available / include raw.")
        return

    literal_block = node[0]

    code      = literal_block.astext()
    hashobj   = code.encode('utf-8') #  str(node.attributes)
    fname     = path.join('%s-%s' % (srclang, sha1(hashobj).hexdigest()))

    tmp_fname = path.join(
        self.builder.outdir, self.builder.imagedir, fname + tmp_ext)

    if not path.isfile(tmp_fname):
        mkdir(path.dirname(tmp_fname))
        with open(tmp_fname, "w") as out:
            out.write(code)

    img_node = nodes.image(node.rawsource, **node.attributes)
    img_node['uri'] = path.join(self.builder.imgpath, fname + tmp_ext)
    img_node['candidates'] = {
        '*': path.join(self.builder.imgpath, fname + tmp_ext)}

    literal_block.replace_self(img_node)
    convert_image(img_node, self, tmp_fname)

class kernel_render(nodes.General, nodes.Inline, nodes.Element):
    """Node for ``kernel-render`` directive."""
    pass

class KernelRender(Figure):
    u"""KernelRender directive

    Render content by external tool.  Has all the options known from the
    *figure*  directive, plus option ``caption``.  If ``caption`` has a
    value, a figure node with the *caption* is inserted. If not, a image node is
    inserted.

    The KernelRender directive wraps the text of the directive into a
    literal_block node and wraps it into a kernel_render node. See
    ``visit_kernel_render``.
    """
    has_content = True
    required_arguments = 1
    optional_arguments = 0
    final_argument_whitespace = False

    # earn options from 'figure'
    option_spec = Figure.option_spec.copy()
    option_spec['caption'] = directives.unchanged

    def run(self):
        return [self.build_node()]

    def build_node(self):

        srclang = self.arguments[0].strip()
        if srclang not in RENDER_MARKUP_EXT.keys():
            return [self.state_machine.reporter.warning(
                'Unknown source language "%s", use one of: %s.' % (
                    srclang, ",".join(RENDER_MARKUP_EXT.keys())),
                line=self.lineno)]

        code = '\n'.join(self.content)
        if not code.strip():
            return [self.state_machine.reporter.warning(
                'Ignoring "%s" directive without content.' % (
                    self.name),
                line=self.lineno)]

        node = kernel_render()
        node['alt'] = self.options.get('alt','')
        node['srclang'] = srclang
        literal_node = nodes.literal_block(code, code)
        node += literal_node

        caption = self.options.get('caption')
        if caption:
            # parse caption's content
            parsed = nodes.Element()
            self.state.nested_parse(
                ViewList([caption], source=''), self.content_offset, parsed)
            caption_node = nodes.caption(
                parsed[0].rawsource, '', *parsed[0].children)
            caption_node.source = parsed[0].source
            caption_node.line = parsed[0].line

            figure_node = nodes.figure('', node)
            for k,v in self.options.items():
                figure_node[k] = v
            figure_node += caption_node

            node = figure_node

        return node

def add_kernel_figure_to_std_domain(app, doctree):
    """Add kernel-figure anchors to 'std' domain.

    The ``StandardDomain.process_doc(..)`` method does not know how to resolve
    the caption (label) of ``kernel-figure`` directive (it only knows about
    standard nodes, e.g. table, figure etc.). Without any additional handling
    this will result in a 'undefined label' for kernel-figures.

    This handle adds labels of kernel-figure to the 'std' domain labels.
    """

    std = app.env.domains["std"]
    docname = app.env.docname
    labels = std.data["labels"]

    for name, explicit in doctree.nametypes.items():
        if not explicit:
            continue
        labelid = doctree.nameids[name]
        if labelid is None:
            continue
        node = doctree.ids[labelid]

        if node.tagname == 'kernel_figure':
            for n in node.next_node():
                if n.tagname == 'caption':
                    sectname = clean_astext(n)
                    # add label to std domain
                    labels[name] = docname, labelid, sectname
                    break


code:
# -*- coding: utf-8; mode: python -*-
# pylint: disable=R0903, C0330, R0914, R0912, E0401

import os
import sys
from sphinx.util.pycompat import execfile_

# ------------------------------------------------------------------------------
def loadConfig(namespace):
# ------------------------------------------------------------------------------

    u"""Load an additional configuration file into *namespace*.

    The name of the configuration file is taken from the environment
    ``SPHINX_CONF``. The external configuration file extends (or overwrites) the
    configuration values from the origin ``conf.py``.  With this you are able to
    maintain *build themes*.  """

    config_file = os.environ.get("SPHINX_CONF", None)
    if (config_file is not None
        and os.path.normpath(namespace["__file__"]) != os.path.normpath(config_file) ):
        config_file = os.path.abspath(config_file)

        # Let's avoid one conf.py file just due to latex_documents
        start = config_file.find('Documentation/')
        if start >= 0:
            start = config_file.find('/', start + 1)

        end = config_file.rfind('/')
        if start >= 0 and end > 0:
            dir = config_file[start + 1:end]

            print("source directory: %s" % dir)
            new_latex_docs = []
            latex_documents = namespace['latex_documents']

            for l in latex_documents:
                if l[0].find(dir + '/') == 0:
                    has = True
                    fn = l[0][len(dir) + 1:]
                    new_latex_docs.append((fn, l[1], l[2], l[3], l[4]))
                    break

            namespace['latex_documents'] = new_latex_docs

        # If there is an extra conf.py file, load it
        if os.path.isfile(config_file):
            sys.stdout.write("load additional sphinx-config: %s\n" % config_file)
            config = namespace.copy()
            config['__file__'] = config_file
            execfile_(config_file, config)
            del config['__file__']
            namespace.update(config)
        else:
            config = namespace.copy()
            config['tags'].add("subproject")
            namespace.update(config)

repo_name: angery/linux


code:
#!/usr/bin/env python
# SPDX-License-Identifier: GPL-2.0
# -*- coding: utf-8; mode: python -*-
# pylint: disable=R0903, C0330, R0914, R0912, E0401

u"""
    maintainers-include
    ~~~~~~~~~~~~~~~~~~~

    Implementation of the ``maintainers-include`` reST-directive.

    :copyright:  Copyright (C) 2019  Kees Cook <keescook@chromium.org>
    :license:    GPL Version 2, June 1991 see linux/COPYING for details.

    The ``maintainers-include`` reST-directive performs extensive parsing
    specific to the Linux kernel's standard "MAINTAINERS" file, in an
    effort to avoid needing to heavily mark up the original plain text.
"""

import sys
import re
import os.path

from docutils import statemachine
from docutils.utils.error_reporting import ErrorString
from docutils.parsers.rst import Directive
from docutils.parsers.rst.directives.misc import Include

__version__  = '1.0'

def setup(app):
    app.add_directive("maintainers-include", MaintainersInclude)
    return dict(
        version = __version__,
        parallel_read_safe = True,
        parallel_write_safe = True
    )

class MaintainersInclude(Include):
    u"""MaintainersInclude (``maintainers-include``) directive"""
    required_arguments = 0

    def parse_maintainers(self, path):
        """Parse all the MAINTAINERS lines into ReST for human-readability"""

        result = list()
        result.append(".. _maintainers:")
        result.append("")

        # Poor man's state machine.
        descriptions = False
        maintainers = False
        subsystems = False

        # Field letter to field name mapping.
        field_letter = None
        fields = dict()

        prev = None
        field_prev = ""
        field_content = ""

        for line in open(path):
            # Have we reached the end of the preformatted Descriptions text?
            if descriptions and line.startswith('Maintainers'):
                descriptions = False
                # Ensure a blank line following the last "|"-prefixed line.
                result.append("")

            # Start subsystem processing? This is to skip processing the text
            # between the Maintainers heading and the first subsystem name.
            if maintainers and not subsystems:
                if re.search('^[A-Z0-9]', line):
                    subsystems = True

            # Drop needless input whitespace.
            line = line.rstrip()

            # Linkify all non-wildcard refs to ReST files in Documentation/.
            pat = '(Documentation/([^\s\?\*]*)\.rst)'
            m = re.search(pat, line)
            if m:
                # maintainers.rst is in a subdirectory, so include "../".
                line = re.sub(pat, ':doc:`%s <../%s>`' % (m.group(2), m.group(2)), line)

            # Check state machine for output rendering behavior.
            output = None
            if descriptions:
                # Escape the escapes in preformatted text.
                output = "| %s" % (line.replace("\\", "\\\\"))
                # Look for and record field letter to field name mappings:
                #   R: Designated *reviewer*: FullName <address@domain>
                m = re.search("\s(\S):\s", line)
                if m:
                    field_letter = m.group(1)
                if field_letter and not field_letter in fields:
                    m = re.search("\*([^\*]+)\*", line)
                    if m:
                        fields[field_letter] = m.group(1)
            elif subsystems:
                # Skip empty lines: subsystem parser adds them as needed.
                if len(line) == 0:
                    continue
                # Subsystem fields are batched into "field_content"
                if line[1] != ':':
                    # Render a subsystem entry as:
                    #   SUBSYSTEM NAME
                    #   ~~~~~~~~~~~~~~

                    # Flush pending field content.
                    output = field_content + "\n\n"
                    field_content = ""

                    # Collapse whitespace in subsystem name.
                    heading = re.sub("\s+", " ", line)
                    output = output + "%s\n%s" % (heading, "~" * len(heading))
                    field_prev = ""
                else:
                    # Render a subsystem field as:
                    #   :Field: entry
                    #           entry...
                    field, details = line.split(':', 1)
                    details = details.strip()

                    # Mark paths (and regexes) as literal text for improved
                    # readability and to escape any escapes.
                    if field in ['F', 'N', 'X', 'K']:
                        # But only if not already marked :)
                        if not ':doc:' in details:
                            details = '``%s``' % (details)

                    # Comma separate email field continuations.
                    if field == field_prev and field_prev in ['M', 'R', 'L']:
                        field_content = field_content + ","

                    # Do not repeat field names, so that field entries
                    # will be collapsed together.
                    if field != field_prev:
                        output = field_content + "\n"
                        field_content = ":%s:" % (fields.get(field, field))
                    field_content = field_content + "\n\t%s" % (details)
                    field_prev = field
            else:
                output = line

            # Re-split on any added newlines in any above parsing.
            if output != None:
                for separated in output.split('\n'):
                    result.append(separated)

            # Update the state machine when we find heading separators.
            if line.startswith('----------'):
                if prev.startswith('Descriptions'):
                    descriptions = True
                if prev.startswith('Maintainers'):
                    maintainers = True

            # Retain previous line for state machine transitions.
            prev = line

        # Flush pending field contents.
        if field_content != "":
            for separated in field_content.split('\n'):
                result.append(separated)

        output = "\n".join(result)
        # For debugging the pre-rendered results...
        #print(output, file=open("/tmp/MAINTAINERS.rst", "w"))

        self.state_machine.insert_input(
          statemachine.string2lines(output), path)

    def run(self):
        """Include the MAINTAINERS file as part of this reST file."""
        if not self.state.document.settings.file_insertion_enabled:
            raise self.warning('"%s" directive disabled.' % self.name)

        # Walk up source path directories to find Documentation/../
        path = self.state_machine.document.attributes['source']
        path = os.path.realpath(path)
        tail = path
        while tail != "Documentation" and tail != "":
            (path, tail) = os.path.split(path)

        # Append "MAINTAINERS"
        path = os.path.join(path, "MAINTAINERS")

        try:
            self.state.document.settings.record_dependencies.add(path)
            lines = self.parse_maintainers(path)
        except IOError as error:
            raise self.severe('Problems with "%s" directive path:\n%s.' %
                      (self.name, ErrorString(error)))

        return []


code:
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0+
#
# Figure out if we should follow a specific parallelism from the make
# environment (as exported by scripts/jobserver-exec), or fall back to
# the "auto" parallelism when "-jN" is not specified at the top-level
# "make" invocation.

sphinx="$1"
shift || true

parallel="$PARALLELISM"
if [ -z "$parallel" ] ; then
	# If no parallelism is specified at the top-level make, then
	# fall back to the expected "-jauto" mode that the "htmldocs"
	# target has had.
	auto=$(perl -e 'open IN,"'"$sphinx"' --version 2>&1 |";
			while (<IN>) {
				if (m/([\d\.]+)/) {
					print "auto" if ($1 >= "1.7")
				}
			}
			close IN')
	if [ -n "$auto" ] ; then
		parallel="$auto"
	fi
fi
# Only if some parallelism has been determined do we add the -jN option.
if [ -n "$parallel" ] ; then
	parallel="-j$parallel"
fi

exec "$sphinx" $parallel "$@"


code:
#!/usr/bin/env perl
use strict;
use Text::Tabs;
use Getopt::Long;
use Pod::Usage;

my $debug;
my $help;
my $man;

GetOptions(
	"debug" => \$debug,
	'usage|?' => \$help,
	'help' => \$man
) or pod2usage(2);

pod2usage(1) if $help;
pod2usage(-exitstatus => 0, -verbose => 2) if $man;
pod2usage(2) if (scalar @ARGV < 2 || scalar @ARGV > 3);

my ($file_in, $file_out, $file_exceptions) = @ARGV;

my $data;
my %ioctls;
my %defines;
my %typedefs;
my %enums;
my %enum_symbols;
my %structs;

require Data::Dumper if ($debug);

#
# read the file and get identifiers
#

my $is_enum = 0;
my $is_comment = 0;
open IN, $file_in or die "Can't open $file_in";
while (<IN>) {
	$data .= $_;

	my $ln = $_;
	if (!$is_comment) {
		$ln =~ s,/\*.*(\*/),,g;

		$is_comment = 1 if ($ln =~ s,/\*.*,,);
	} else {
		if ($ln =~ s,^(.*\*/),,) {
			$is_comment = 0;
		} else {
			next;
		}
	}

	if ($is_enum && $ln =~ m/^\s*([_\w][\w\d_]+)\s*[\,=]?/) {
		my $s = $1;
		my $n = $1;
		$n =~ tr/A-Z/a-z/;
		$n =~ tr/_/-/;

		$enum_symbols{$s} =  "\\ :ref:`$s <$n>`\\ ";

		$is_enum = 0 if ($is_enum && m/\}/);
		next;
	}
	$is_enum = 0 if ($is_enum && m/\}/);

	if ($ln =~ m/^\s*#\s*define\s+([_\w][\w\d_]+)\s+_IO/) {
		my $s = $1;
		my $n = $1;
		$n =~ tr/A-Z/a-z/;

		$ioctls{$s} = "\\ :ref:`$s <$n>`\\ ";
		next;
	}

	if ($ln =~ m/^\s*#\s*define\s+([_\w][\w\d_]+)\s+/) {
		my $s = $1;
		my $n = $1;
		$n =~ tr/A-Z/a-z/;
		$n =~ tr/_/-/;

		$defines{$s} = "\\ :ref:`$s <$n>`\\ ";
		next;
	}

	if ($ln =~ m/^\s*typedef\s+([_\w][\w\d_]+)\s+(.*)\s+([_\w][\w\d_]+);/) {
		my $s = $2;
		my $n = $3;

		$typedefs{$n} = "\\ :c:type:`$n <$s>`\\ ";
		next;
	}
	if ($ln =~ m/^\s*enum\s+([_\w][\w\d_]+)\s+\{/
	    || $ln =~ m/^\s*enum\s+([_\w][\w\d_]+)$/
	    || $ln =~ m/^\s*typedef\s*enum\s+([_\w][\w\d_]+)\s+\{/
	    || $ln =~ m/^\s*typedef\s*enum\s+([_\w][\w\d_]+)$/) {
		my $s = $1;

		$enums{$s} =  "enum :c:type:`$s`\\ ";

		$is_enum = $1;
		next;
	}
	if ($ln =~ m/^\s*struct\s+([_\w][\w\d_]+)\s+\{/
	    || $ln =~ m/^\s*struct\s+([[_\w][\w\d_]+)$/
	    || $ln =~ m/^\s*typedef\s*struct\s+([_\w][\w\d_]+)\s+\{/
	    || $ln =~ m/^\s*typedef\s*struct\s+([[_\w][\w\d_]+)$/
	    ) {
		my $s = $1;

		$structs{$s} = "struct $s\\ ";
		next;
	}
}
close IN;

#
# Handle multi-line typedefs
#

my @matches = ($data =~ m/typedef\s+struct\s+\S+?\s*\{[^\}]+\}\s*(\S+)\s*\;/g,
	       $data =~ m/typedef\s+enum\s+\S+?\s*\{[^\}]+\}\s*(\S+)\s*\;/g,);
foreach my $m (@matches) {
	my $s = $m;

	$typedefs{$s} = "\\ :c:type:`$s`\\ ";
	next;
}

#
# Handle exceptions, if any
#

my %def_reftype = (
	"ioctl"   => ":ref",
	"define"  => ":ref",
	"symbol"  => ":ref",
	"typedef" => ":c:type",
	"enum"    => ":c:type",
	"struct"  => ":c:type",
);

if ($file_exceptions) {
	open IN, $file_exceptions or die "Can't read $file_exceptions";
	while (<IN>) {
		next if (m/^\s*$/ || m/^\s*#/);

		# Parsers to ignore a symbol

		if (m/^ignore\s+ioctl\s+(\S+)/) {
			delete $ioctls{$1} if (exists($ioctls{$1}));
			next;
		}
		if (m/^ignore\s+define\s+(\S+)/) {
			delete $defines{$1} if (exists($defines{$1}));
			next;
		}
		if (m/^ignore\s+typedef\s+(\S+)/) {
			delete $typedefs{$1} if (exists($typedefs{$1}));
			next;
		}
		if (m/^ignore\s+enum\s+(\S+)/) {
			delete $enums{$1} if (exists($enums{$1}));
			next;
		}
		if (m/^ignore\s+struct\s+(\S+)/) {
			delete $structs{$1} if (exists($structs{$1}));
			next;
		}
		if (m/^ignore\s+symbol\s+(\S+)/) {
			delete $enum_symbols{$1} if (exists($enum_symbols{$1}));
			next;
		}

		# Parsers to replace a symbol
		my ($type, $old, $new, $reftype);

		if (m/^replace\s+(\S+)\s+(\S+)\s+(\S+)/) {
			$type = $1;
			$old = $2;
			$new = $3;
		} else {
			die "Can't parse $file_exceptions: $_";
		}

		if ($new =~ m/^\:c\:(data|func|macro|type)\:\`(.+)\`/) {
			$reftype = ":c:$1";
			$new = $2;
		} elsif ($new =~ m/\:ref\:\`(.+)\`/) {
			$reftype = ":ref";
			$new = $1;
		} else {
			$reftype = $def_reftype{$type};
		}
		$new = "$reftype:`$old <$new>`";

		if ($type eq "ioctl") {
			$ioctls{$old} = $new if (exists($ioctls{$old}));
			next;
		}
		if ($type eq "define") {
			$defines{$old} = $new if (exists($defines{$old}));
			next;
		}
		if ($type eq "symbol") {
			$enum_symbols{$old} = $new if (exists($enum_symbols{$old}));
			next;
		}
		if ($type eq "typedef") {
			$typedefs{$old} = $new if (exists($typedefs{$old}));
			next;
		}
		if ($type eq "enum") {
			$enums{$old} = $new if (exists($enums{$old}));
			next;
		}
		if ($type eq "struct") {
			$structs{$old} = $new if (exists($structs{$old}));
			next;
		}

		die "Can't parse $file_exceptions: $_";
	}
}

if ($debug) {
	print Data::Dumper->Dump([\%ioctls], [qw(*ioctls)]) if (%ioctls);
	print Data::Dumper->Dump([\%typedefs], [qw(*typedefs)]) if (%typedefs);
	print Data::Dumper->Dump([\%enums], [qw(*enums)]) if (%enums);
	print Data::Dumper->Dump([\%structs], [qw(*structs)]) if (%structs);
	print Data::Dumper->Dump([\%defines], [qw(*defines)]) if (%defines);
	print Data::Dumper->Dump([\%enum_symbols], [qw(*enum_symbols)]) if (%enum_symbols);
}

#
# Align block
#
$data = expand($data);
$data = "    " . $data;
$data =~ s/\n/\n    /g;
$data =~ s/\n\s+$/\n/g;
$data =~ s/\n\s+\n/\n\n/g;

#
# Add escape codes for special characters
#
$data =~ s,([\_\`\*\<\>\&\\\\:\/\|\%\$\#\{\}\~\^]),\\$1,g;

$data =~ s,DEPRECATED,**DEPRECATED**,g;

#
# Add references
#

my $start_delim = "[ \n\t\(\=\*\@]";
my $end_delim = "(\\s|,|\\\\=|\\\\:|\\;|\\\)|\\}|\\{)";

foreach my $r (keys %ioctls) {
	my $s = $ioctls{$r};

	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;

	print "$r -> $s\n" if ($debug);

	$data =~ s/($start_delim)($r)$end_delim/$1$s$3/g;
}

foreach my $r (keys %defines) {
	my $s = $defines{$r};

	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;

	print "$r -> $s\n" if ($debug);

	$data =~ s/($start_delim)($r)$end_delim/$1$s$3/g;
}

foreach my $r (keys %enum_symbols) {
	my $s = $enum_symbols{$r};

	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;

	print "$r -> $s\n" if ($debug);

	$data =~ s/($start_delim)($r)$end_delim/$1$s$3/g;
}

foreach my $r (keys %enums) {
	my $s = $enums{$r};

	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;

	print "$r -> $s\n" if ($debug);

	$data =~ s/enum\s+($r)$end_delim/$s$2/g;
}

foreach my $r (keys %structs) {
	my $s = $structs{$r};

	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;

	print "$r -> $s\n" if ($debug);

	$data =~ s/struct\s+($r)$end_delim/$s$2/g;
}

foreach my $r (keys %typedefs) {
	my $s = $typedefs{$r};

	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;

	print "$r -> $s\n" if ($debug);
	$data =~ s/($start_delim)($r)$end_delim/$1$s$3/g;
}

$data =~ s/\\ ([\n\s])/\1/g;

#
# Generate output file
#

my $title = $file_in;
$title =~ s,.*/,,;

open OUT, "> $file_out" or die "Can't open $file_out";
print OUT ".. -*- coding: utf-8; mode: rst -*-\n\n";
print OUT "$title\n";
print OUT "=" x length($title);
print OUT "\n\n.. parsed-literal::\n\n";
print OUT $data;
close OUT;

__END__

=head1 NAME

parse_headers.pl - parse a C file, in order to identify functions, structs,
enums and defines and create cross-references to a Sphinx book.

=head1 SYNOPSIS

B<parse_headers.pl> [<options>] <C_FILE> <OUT_FILE> [<EXCEPTIONS_FILE>]

Where <options> can be: --debug, --help or --usage.

=head1 OPTIONS

=over 8

=item B<--debug>

Put the script in verbose mode, useful for debugging.

=item B<--usage>

Prints a brief help message and exits.

=item B<--help>

Prints a more detailed help message and exits.

=back

=head1 DESCRIPTION

Convert a C header or source file (C_FILE), into a ReStructured Text
included via ..parsed-literal block with cross-references for the
documentation files that describe the API. It accepts an optional
EXCEPTIONS_FILE with describes what elements will be either ignored or
be pointed to a non-default reference.

The output is written at the (OUT_FILE).

It is capable of identifying defines, functions, structs, typedefs,
enums and enum symbols and create cross-references for all of them.
It is also capable of distinguish #define used for specifying a Linux
ioctl.

The EXCEPTIONS_FILE contain two rules to allow ignoring a symbol or
to replace the default references by a custom one.

Please read Documentation/doc-guide/parse-headers.rst at the Kernel's
tree for more details.

=head1 BUGS

Report bugs to Mauro Carvalho Chehab <mchehab@kernel.org>

=head1 COPYRIGHT

Copyright (c) 2016 by Mauro Carvalho Chehab <mchehab+samsung@kernel.org>.

License GPLv2: GNU GPL version 2 <https://gnu.org/licenses/gpl.html>.

This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

=cut


code:
# jinja2>=3.1 is not compatible with Sphinx<4.0
jinja2<3.1
Sphinx==2.4.4


code:
#!/usr/bin/env python3
# -*- coding: utf-8; mode: python -*-
# pylint: disable=C0330, R0903, R0912

u"""
    flat-table
    ~~~~~~~~~~

    Implementation of the ``flat-table`` reST-directive.

    :copyright:  Copyright (C) 2016  Markus Heiser
    :license:    GPL Version 2, June 1991 see linux/COPYING for details.

    The ``flat-table`` (:py:class:`FlatTable`) is a double-stage list similar to
    the ``list-table`` with some additional features:

    * *column-span*: with the role ``cspan`` a cell can be extended through
      additional columns

    * *row-span*: with the role ``rspan`` a cell can be extended through
      additional rows

    * *auto span* rightmost cell of a table row over the missing cells on the
      right side of that table-row.  With Option ``:fill-cells:`` this behavior
      can be changed from *auto span* to *auto fill*, which automatically inserts
      (empty) cells instead of spanning the last cell.

    Options:

    * header-rows:   [int] count of header rows
    * stub-columns:  [int] count of stub columns
    * widths:        [[int] [int] ... ] widths of columns
    * fill-cells:    instead of autospann missing cells, insert missing cells

    roles:

    * cspan: [int] additionale columns (*morecols*)
    * rspan: [int] additionale rows (*morerows*)
"""

# ==============================================================================
# imports
# ==============================================================================

from docutils import nodes
from docutils.parsers.rst import directives, roles
from docutils.parsers.rst.directives.tables import Table
from docutils.utils import SystemMessagePropagation

# ==============================================================================
# common globals
# ==============================================================================

__version__  = '1.0'

# ==============================================================================
def setup(app):
# ==============================================================================

    app.add_directive("flat-table", FlatTable)
    roles.register_local_role('cspan', c_span)
    roles.register_local_role('rspan', r_span)

    return dict(
        version = __version__,
        parallel_read_safe = True,
        parallel_write_safe = True
    )

# ==============================================================================
def c_span(name, rawtext, text, lineno, inliner, options=None, content=None):
# ==============================================================================
    # pylint: disable=W0613

    options  = options if options is not None else {}
    content  = content if content is not None else []
    nodelist = [colSpan(span=int(text))]
    msglist  = []
    return nodelist, msglist

# ==============================================================================
def r_span(name, rawtext, text, lineno, inliner, options=None, content=None):
# ==============================================================================
    # pylint: disable=W0613

    options  = options if options is not None else {}
    content  = content if content is not None else []
    nodelist = [rowSpan(span=int(text))]
    msglist  = []
    return nodelist, msglist

# ==============================================================================
class rowSpan(nodes.General, nodes.Element): pass # pylint: disable=C0103,C0321
class colSpan(nodes.General, nodes.Element): pass # pylint: disable=C0103,C0321
# ==============================================================================

# ==============================================================================
class FlatTable(Table):
# ==============================================================================

    u"""FlatTable (``flat-table``) directive"""

    option_spec = {
        'name': directives.unchanged
        , 'class': directives.class_option
        , 'header-rows': directives.nonnegative_int
        , 'stub-columns': directives.nonnegative_int
        , 'widths': directives.positive_int_list
        , 'fill-cells' : directives.flag }

    def run(self):

        if not self.content:
            error = self.state_machine.reporter.error(
                'The "%s" directive is empty; content required.' % self.name,
                nodes.literal_block(self.block_text, self.block_text),
                line=self.lineno)
            return [error]

        title, messages = self.make_title()
        node = nodes.Element()          # anonymous container for parsing
        self.state.nested_parse(self.content, self.content_offset, node)

        tableBuilder = ListTableBuilder(self)
        tableBuilder.parseFlatTableNode(node)
        tableNode = tableBuilder.buildTableNode()
        # SDK.CONSOLE()  # print --> tableNode.asdom().toprettyxml()
        if title:
            tableNode.insert(0, title)
        return [tableNode] + messages

# ==============================================================================
class ListTableBuilder(object):
# ==============================================================================

    u"""Builds a table from a double-stage list"""

    def __init__(self, directive):
        self.directive = directive
        self.rows      = []
        self.max_cols  = 0

    def buildTableNode(self):

        colwidths    = self.directive.get_column_widths(self.max_cols)
        if isinstance(colwidths, tuple):
            # Since docutils 0.13, get_column_widths returns a (widths,
            # colwidths) tuple, where widths is a string (i.e. 'auto').
            # See https://sourceforge.net/p/docutils/patches/120/.
            colwidths = colwidths[1]
        stub_columns = self.directive.options.get('stub-columns', 0)
        header_rows  = self.directive.options.get('header-rows', 0)

        table = nodes.table()
        tgroup = nodes.tgroup(cols=len(colwidths))
        table += tgroup

        for colwidth in colwidths:
            colspec = nodes.colspec(colwidth=colwidth)
            # FIXME: It seems, that the stub method only works well in the
            # absence of rowspan (observed by the html builder, the docutils-xml
            # build seems OK).  This is not extraordinary, because there exists
            # no table directive (except *this* flat-table) which allows to
            # define coexistent of rowspan and stubs (there was no use-case
            # before flat-table). This should be reviewed (later).
            if stub_columns:
                colspec.attributes['stub'] = 1
                stub_columns -= 1
            tgroup += colspec
        stub_columns = self.directive.options.get('stub-columns', 0)

        if header_rows:
            thead = nodes.thead()
            tgroup += thead
            for row in self.rows[:header_rows]:
                thead += self.buildTableRowNode(row)

        tbody = nodes.tbody()
        tgroup += tbody

        for row in self.rows[header_rows:]:
            tbody += self.buildTableRowNode(row)
        return table

    def buildTableRowNode(self, row_data, classes=None):
        classes = [] if classes is None else classes
        row = nodes.row()
        for cell in row_data:
            if cell is None:
                continue
            cspan, rspan, cellElements = cell

            attributes = {"classes" : classes}
            if rspan:
                attributes['morerows'] = rspan
            if cspan:
                attributes['morecols'] = cspan
            entry = nodes.entry(**attributes)
            entry.extend(cellElements)
            row += entry
        return row

    def raiseError(self, msg):
        error =  self.directive.state_machine.reporter.error(
            msg
            , nodes.literal_block(self.directive.block_text
                                  , self.directive.block_text)
            , line = self.directive.lineno )
        raise SystemMessagePropagation(error)

    def parseFlatTableNode(self, node):
        u"""parses the node from a :py:class:`FlatTable` directive's body"""

        if len(node) != 1 or not isinstance(node[0], nodes.bullet_list):
            self.raiseError(
                'Error parsing content block for the "%s" directive: '
                'exactly one bullet list expected.' % self.directive.name )

        for rowNum, rowItem in enumerate(node[0]):
            row = self.parseRowItem(rowItem, rowNum)
            self.rows.append(row)
        self.roundOffTableDefinition()

    def roundOffTableDefinition(self):
        u"""Round off the table definition.

        This method rounds off the table definition in :py:member:`rows`.

        * This method inserts the needed ``None`` values for the missing cells
        arising from spanning cells over rows and/or columns.

        * recount the :py:member:`max_cols`

        * Autospan or fill (option ``fill-cells``) missing cells on the right
          side of the table-row
        """

        y = 0
        while y < len(self.rows):
            x = 0

            while x < len(self.rows[y]):
                cell = self.rows[y][x]
                if cell is None:
                    x += 1
                    continue
                cspan, rspan = cell[:2]
                # handle colspan in current row
                for c in range(cspan):
                    try:
                        self.rows[y].insert(x+c+1, None)
                    except: # pylint: disable=W0702
                        # the user sets ambiguous rowspans
                        pass # SDK.CONSOLE()
                # handle colspan in spanned rows
                for r in range(rspan):
                    for c in range(cspan + 1):
                        try:
                            self.rows[y+r+1].insert(x+c, None)
                        except: # pylint: disable=W0702
                            # the user sets ambiguous rowspans
                            pass # SDK.CONSOLE()
                x += 1
            y += 1

        # Insert the missing cells on the right side. For this, first
        # re-calculate the max columns.

        for row in self.rows:
            if self.max_cols < len(row):
                self.max_cols = len(row)

        # fill with empty cells or cellspan?

        fill_cells = False
        if 'fill-cells' in self.directive.options:
            fill_cells = True

        for row in self.rows:
            x =  self.max_cols - len(row)
            if x and not fill_cells:
                if row[-1] is None:
                    row.append( ( x - 1, 0, []) )
                else:
                    cspan, rspan, content = row[-1]
                    row[-1] = (cspan + x, rspan, content)
            elif x and fill_cells:
                for i in range(x):
                    row.append( (0, 0, nodes.comment()) )

    def pprint(self):
        # for debugging
        retVal = "[   "
        for row in self.rows:
            retVal += "[ "
            for col in row:
                if col is None:
                    retVal += ('%r' % col)
                    retVal += "\n    , "
                else:
                    content = col[2][0].astext()
                    if len (content) > 30:
                        content = content[:30] + "..."
                    retVal += ('(cspan=%s, rspan=%s, %r)'
                               % (col[0], col[1], content))
                    retVal += "]\n    , "
            retVal = retVal[:-2]
            retVal += "]\n  , "
        retVal = retVal[:-2]
        return retVal + "]"

    def parseRowItem(self, rowItem, rowNum):
        row = []
        childNo = 0
        error   = False
        cell    = None
        target  = None

        for child in rowItem:
            if (isinstance(child , nodes.comment)
                or isinstance(child, nodes.system_message)):
                pass
            elif isinstance(child , nodes.target):
                target = child
            elif isinstance(child, nodes.bullet_list):
                childNo += 1
                cell = child
            else:
                error = True
                break

        if childNo != 1 or error:
            self.raiseError(
                'Error parsing content block for the "%s" directive: '
                'two-level bullet list expected, but row %s does not '
                'contain a second-level bullet list.'
                % (self.directive.name, rowNum + 1))

        for cellItem in cell:
            cspan, rspan, cellElements = self.parseCellItem(cellItem)
            if target is not None:
                cellElements.insert(0, target)
            row.append( (cspan, rspan, cellElements) )
        return row

    def parseCellItem(self, cellItem):
        # search and remove cspan, rspan colspec from the first element in
        # this listItem (field).
        cspan = rspan = 0
        if not len(cellItem):
            return cspan, rspan, []
        for elem in cellItem[0]:
            if isinstance(elem, colSpan):
                cspan = elem.get("span")
                elem.parent.remove(elem)
                continue
            if isinstance(elem, rowSpan):
                rspan = elem.get("span")
                elem.parent.remove(elem)
                continue
        return cspan, rspan, cellItem[:]


code:
===================================================
spi_butterfly - parport-to-butterfly adapter driver
===================================================

This is a hardware and software project that includes building and using
a parallel port adapter cable, together with an "AVR Butterfly" to run
firmware for user interfacing and/or sensors.  A Butterfly is a $US20
battery powered card with an AVR microcontroller and lots of goodies:
sensors, LCD, flash, toggle stick, and more.  You can use AVR-GCC to
develop firmware for this, and flash it using this adapter cable.

You can make this adapter from an old printer cable and solder things
directly to the Butterfly.  Or (if you have the parts and skills) you
can come up with something fancier, providing circuit protection to the
Butterfly and the printer port, or with a better power supply than two
signal pins from the printer port.  Or for that matter, you can use
similar cables to talk to many AVR boards, even a breadboard.

This is more powerful than "ISP programming" cables since it lets kernel
SPI protocol drivers interact with the AVR, and could even let the AVR
issue interrupts to them.  Later, your protocol driver should work
easily with a "real SPI controller", instead of this bitbanger.

The first cable connections will hook Linux up to one SPI bus, with the
AVR and a DataFlash chip; and to the AVR reset line.  This is all you
need to reflash the firmware, and the pins are the standard Atmel "ISP"
connector pins (used also on non-Butterfly AVR boards).  On the parport
side this is like "sp12" programming cables.

	======	  =============	  ===================
	Signal	  Butterfly	  Parport (DB-25)
	======	  =============	  ===================
	SCK	  J403.PB1/SCK	  pin 2/D0
	RESET	  J403.nRST	  pin 3/D1
	VCC	  J403.VCC_EXT	  pin 8/D6
	MOSI	  J403.PB2/MOSI	  pin 9/D7
	MISO	  J403.PB3/MISO	  pin 11/S7,nBUSY
	GND	  J403.GND	  pin 23/GND
	======	  =============	  ===================

Then to let Linux master that bus to talk to the DataFlash chip, you must
(a) flash new firmware that disables SPI (set PRR.2, and disable pullups
by clearing PORTB.[0-3]); (b) configure the mtd_dataflash driver; and
(c) cable in the chipselect.

	======	  ============	  ===================
	Signal	  Butterfly	  Parport (DB-25)
	======	  ============	  ===================
	VCC	  J400.VCC_EXT	  pin 7/D5
	SELECT	  J400.PB0/nSS	  pin 17/C3,nSELECT
	GND	  J400.GND	  pin 24/GND
	======	  ============	  ===================

Or you could flash firmware making the AVR into an SPI slave (keeping the
DataFlash in reset) and tweak the spi_butterfly driver to make it bind to
the driver for your custom SPI-based protocol.

The "USI" controller, using J405, can also be used for a second SPI bus.
That would let you talk to the AVR using custom SPI-with-USI firmware,
while letting either Linux or the AVR use the DataFlash.  There are plenty
of spare parport pins to wire this one up, such as:

	======	  =============	  ===================
	Signal	  Butterfly	  Parport (DB-25)
	======	  =============	  ===================
	SCK	  J403.PE4/USCK	  pin 5/D3
	MOSI	  J403.PE5/DI	  pin 6/D4
	MISO	  J403.PE6/DO	  pin 12/S5,nPAPEROUT
	GND	  J403.GND	  pin 22/GND

	IRQ	  J402.PF4	  pin 10/S6,ACK
	GND	  J402.GND(P2)	  pin 25/GND
	======	  =============	  ===================


code:
.. SPDX-License-Identifier: GPL-2.0

=================================
Serial Peripheral Interface (SPI)
=================================

.. toctree::
   :maxdepth: 1

   spi-summary
   spidev
   butterfly
   pxa2xx
   spi-lm70llp
   spi-sc18is602

.. only::  subproject and html

   Indices
   =======

   * :ref:`genindex`


code:
==============================
PXA2xx SPI on SSP driver HOWTO
==============================

This a mini HOWTO on the pxa2xx_spi driver. The driver turns a PXA2xx
synchronous serial port into an SPI master controller
(see Documentation/spi/spi-summary.rst). The driver has the following features

- Support for any PXA2xx and compatible SSP.
- SSP PIO and SSP DMA data transfers.
- External and Internal (SSPFRM) chip selects.
- Per slave device (chip) configuration.
- Full suspend, freeze, resume support.

The driver is built around a &struct spi_message FIFO serviced by kernel
thread. The kernel thread, spi_pump_messages(), drives message FIFO and
is responsible for queuing SPI transactions and setting up and launching
the DMA or interrupt driven transfers.

Declaring PXA2xx Master Controllers
-----------------------------------
Typically, for a legacy platform, an SPI master is defined in the
arch/.../mach-*/board-*.c as a "platform device". The master configuration
is passed to the driver via a table found in include/linux/spi/pxa2xx_spi.h::

  struct pxa2xx_spi_controller {
	u16 num_chipselect;
	u8 enable_dma;
	...
  };

The "pxa2xx_spi_controller.num_chipselect" field is used to determine the number of
slave device (chips) attached to this SPI master.

The "pxa2xx_spi_controller.enable_dma" field informs the driver that SSP DMA should
be used. This caused the driver to acquire two DMA channels: Rx channel and
Tx channel. The Rx channel has a higher DMA service priority than the Tx channel.
See the "PXA2xx Developer Manual" section "DMA Controller".

For the new platforms the description of the controller and peripheral devices
comes from Device Tree or ACPI.

NSSP MASTER SAMPLE
------------------
Below is a sample configuration using the PXA255 NSSP for a legacy platform::

  static struct resource pxa_spi_nssp_resources[] = {
	[0] = {
		.start	= __PREG(SSCR0_P(2)), /* Start address of NSSP */
		.end	= __PREG(SSCR0_P(2)) + 0x2c, /* Range of registers */
		.flags	= IORESOURCE_MEM,
	},
	[1] = {
		.start	= IRQ_NSSP, /* NSSP IRQ */
		.end	= IRQ_NSSP,
		.flags	= IORESOURCE_IRQ,
	},
  };

  static struct pxa2xx_spi_controller pxa_nssp_master_info = {
	.num_chipselect = 1, /* Matches the number of chips attached to NSSP */
	.enable_dma = 1, /* Enables NSSP DMA */
  };

  static struct platform_device pxa_spi_nssp = {
	.name = "pxa2xx-spi", /* MUST BE THIS VALUE, so device match driver */
	.id = 2, /* Bus number, MUST MATCH SSP number 1..n */
	.resource = pxa_spi_nssp_resources,
	.num_resources = ARRAY_SIZE(pxa_spi_nssp_resources),
	.dev = {
		.platform_data = &pxa_nssp_master_info, /* Passed to driver */
	},
  };

  static struct platform_device *devices[] __initdata = {
	&pxa_spi_nssp,
  };

  static void __init board_init(void)
  {
	(void)platform_add_device(devices, ARRAY_SIZE(devices));
  }

Declaring Slave Devices
-----------------------
Typically, for a legacy platform, each SPI slave (chip) is defined in the
arch/.../mach-*/board-*.c using the "spi_board_info" structure found in
"linux/spi/spi.h". See "Documentation/spi/spi-summary.rst" for additional
information.

Each slave device attached to the PXA must provide slave specific configuration
information via the structure "pxa2xx_spi_chip" found in
"include/linux/spi/pxa2xx_spi.h".  The pxa2xx_spi master controller driver
will uses the configuration whenever the driver communicates with the slave
device. All fields are optional.

::

  struct pxa2xx_spi_chip {
	u8 tx_threshold;
	u8 rx_threshold;
	u8 dma_burst_size;
	u32 timeout;
  };

The "pxa2xx_spi_chip.tx_threshold" and "pxa2xx_spi_chip.rx_threshold" fields are
used to configure the SSP hardware FIFO. These fields are critical to the
performance of pxa2xx_spi driver and misconfiguration will result in rx
FIFO overruns (especially in PIO mode transfers). Good default values are::

	.tx_threshold = 8,
	.rx_threshold = 8,

The range is 1 to 16 where zero indicates "use default".

The "pxa2xx_spi_chip.dma_burst_size" field is used to configure PXA2xx DMA
engine and is related the "spi_device.bits_per_word" field.  Read and understand
the PXA2xx "Developer Manual" sections on the DMA controller and SSP Controllers
to determine the correct value. An SSP configured for byte-wide transfers would
use a value of 8. The driver will determine a reasonable default if
dma_burst_size == 0.

The "pxa2xx_spi_chip.timeout" fields is used to efficiently handle
trailing bytes in the SSP receiver FIFO. The correct value for this field is
dependent on the SPI bus speed ("spi_board_info.max_speed_hz") and the specific
slave device.  Please note that the PXA2xx SSP 1 does not support trailing byte
timeouts and must busy-wait any trailing bytes.

NOTE: the SPI driver cannot control the chip select if SSPFRM is used, so the
chipselect is dropped after each spi_transfer.  Most devices need chip select
asserted around the complete message. Use SSPFRM as a GPIO (through a descriptor)
to accommodate these chips.

NSSP SLAVE SAMPLE
-----------------
For a legacy platform or in some other cases, the pxa2xx_spi_chip structure
is passed to the pxa2xx_spi driver in the "spi_board_info.controller_data"
field. Below is a sample configuration using the PXA255 NSSP.

::

  static struct pxa2xx_spi_chip cs8415a_chip_info = {
	.tx_threshold = 8, /* SSP hardward FIFO threshold */
	.rx_threshold = 8, /* SSP hardward FIFO threshold */
	.dma_burst_size = 8, /* Byte wide transfers used so 8 byte bursts */
	.timeout = 235, /* See Intel documentation */
  };

  static struct pxa2xx_spi_chip cs8405a_chip_info = {
	.tx_threshold = 8, /* SSP hardward FIFO threshold */
	.rx_threshold = 8, /* SSP hardward FIFO threshold */
	.dma_burst_size = 8, /* Byte wide transfers used so 8 byte bursts */
	.timeout = 235, /* See Intel documentation */
  };

  static struct spi_board_info streetracer_spi_board_info[] __initdata = {
	{
		.modalias = "cs8415a", /* Name of spi_driver for this device */
		.max_speed_hz = 3686400, /* Run SSP as fast a possbile */
		.bus_num = 2, /* Framework bus number */
		.chip_select = 0, /* Framework chip select */
		.platform_data = NULL; /* No spi_driver specific config */
		.controller_data = &cs8415a_chip_info, /* Master chip config */
		.irq = STREETRACER_APCI_IRQ, /* Slave device interrupt */
	},
	{
		.modalias = "cs8405a", /* Name of spi_driver for this device */
		.max_speed_hz = 3686400, /* Run SSP as fast a possbile */
		.bus_num = 2, /* Framework bus number */
		.chip_select = 1, /* Framework chip select */
		.controller_data = &cs8405a_chip_info, /* Master chip config */
		.irq = STREETRACER_APCI_IRQ, /* Slave device interrupt */
	},
  };

  static void __init streetracer_init(void)
  {
	spi_register_board_info(streetracer_spi_board_info,
				ARRAY_SIZE(streetracer_spi_board_info));
  }

DMA and PIO I/O Support
-----------------------
The pxa2xx_spi driver supports both DMA and interrupt driven PIO message
transfers.  The driver defaults to PIO mode and DMA transfers must be enabled
by setting the "enable_dma" flag in the "pxa2xx_spi_controller" structure.
For the newer platforms, that are known to support DMA, the driver will enable
it automatically and try it first with a possible fallback to PIO. The DMA
mode supports both coherent and stream based DMA mappings.

The following logic is used to determine the type of I/O to be used on
a per "spi_transfer" basis::

  if !enable_dma then
	always use PIO transfers

  if spi_message.len > 8191 then
	print "rate limited" warning
	use PIO transfers

  if spi_message.is_dma_mapped and rx_dma_buf != 0 and tx_dma_buf != 0 then
	use coherent DMA mode

  if rx_buf and tx_buf are aligned on 8 byte boundary then
	use streaming DMA mode

  otherwise
	use PIO transfer

THANKS TO
---------
David Brownell and others for mentoring the development of this driver.


code:
==============================================
spi_lm70llp :  LM70-LLP parport-to-SPI adapter
==============================================

Supported board/chip:

  * National Semiconductor LM70 LLP evaluation board

    Datasheet: http://www.national.com/pf/LM/LM70.html

Author:
        Kaiwan N Billimoria <kaiwan@designergraphix.com>

Description
-----------
This driver provides glue code connecting a National Semiconductor LM70 LLP
temperature sensor evaluation board to the kernel's SPI core subsystem.

This is a SPI master controller driver. It can be used in conjunction with
(layered under) the LM70 logical driver (a "SPI protocol driver").
In effect, this driver turns the parallel port interface on the eval board
into a SPI bus with a single device, which will be driven by the generic
LM70 driver (drivers/hwmon/lm70.c).

Hardware Interfacing
--------------------
The schematic for this particular board (the LM70EVAL-LLP) is
available (on page 4) here:

  http://www.national.com/appinfo/tempsensors/files/LM70LLPEVALmanual.pdf

The hardware interfacing on the LM70 LLP eval board is as follows:

   ======== == =========   ==========
   Parallel                 LM70 LLP
     Port   .  Direction   JP2 Header
   ======== == =========   ==========
      D0     2      -         -
      D1     3     -->      V+   5
      D2     4     -->      V+   5
      D3     5     -->      V+   5
      D4     6     -->      V+   5
      D5     7     -->      nCS  8
      D6     8     -->      SCLK 3
      D7     9     -->      SI/O 5
     GND    25      -       GND  7
    Select  13     <--      SI/O 1
   ======== == =========   ==========

Note that since the LM70 uses a "3-wire" variant of SPI, the SI/SO pin
is connected to both pin D7 (as Master Out) and Select (as Master In)
using an arrangement that lets either the parport or the LM70 pull the
pin low.  This can't be shared with true SPI devices, but other 3-wire
devices might share the same SI/SO pin.

The bitbanger routine in this driver (lm70_txrx) is called back from
the bound "hwmon/lm70" protocol driver through its sysfs hook, using a
spi_write_then_read() call.  It performs Mode 0 (SPI/Microwire) bitbanging.
The lm70 driver then inteprets the resulting digital temperature value
and exports it through sysfs.

A "gotcha": National Semiconductor's LM70 LLP eval board circuit schematic
shows that the SI/O line from the LM70 chip is connected to the base of a
transistor Q1 (and also a pullup, and a zener diode to D7); while the
collector is tied to VCC.

Interpreting this circuit, when the LM70 SI/O line is High (or tristate
and not grounded by the host via D7), the transistor conducts and switches
the collector to zero, which is reflected on pin 13 of the DB25 parport
connector.  When SI/O is Low (driven by the LM70 or the host) on the other
hand, the transistor is cut off and the voltage tied to it's collector is
reflected on pin 13 as a High level.

So: the getmiso inline routine in this driver takes this fact into account,
inverting the value read at pin 13.

Thanks to
---------

- David Brownell for mentoring the SPI-side driver development.
- Dr.Craig Hollabaugh for the (early) "manual" bitbanging driver version.
- Nadir Billimoria for help interpreting the circuit schematic.


code:
===========================
Kernel driver spi-sc18is602
===========================

Supported chips:

  * NXP SI18IS602/602B/603

    Datasheet: https://www.nxp.com/documents/data_sheet/SC18IS602_602B_603.pdf

Author:
        Guenter Roeck <linux@roeck-us.net>

Description
-----------

This driver provides connects a NXP SC18IS602/603 I2C-bus to SPI bridge to the
kernel's SPI core subsystem.

The driver does not probe for supported chips, since the SI18IS602/603 does not
support Chip ID registers. You will have to instantiate the devices explicitly.
Please see Documentation/i2c/instantiating-devices.rst for details.

Usage Notes
-----------

This driver requires the I2C adapter driver to support raw I2C messages. I2C
adapter drivers which can only handle the SMBus protocol are not supported.

The maximum SPI message size supported by SC18IS602/603 is 200 bytes. Attempts
to initiate longer transfers will fail with -EINVAL. EEPROM read operations and
similar large accesses have to be split into multiple chunks of no more than
200 bytes per SPI message (128 bytes of data per message is recommended). This
means that programs such as "cp" or "od", which automatically use large block
sizes to access a device, can not be used directly to read data from EEPROM.
Programs such as dd, where the block size can be specified, should be used
instead.


code:
====================================
Overview of Linux kernel SPI support
====================================

02-Feb-2012

What is SPI?
------------
The "Serial Peripheral Interface" (SPI) is a synchronous four wire serial
link used to connect microcontrollers to sensors, memory, and peripherals.
It's a simple "de facto" standard, not complicated enough to acquire a
standardization body.  SPI uses a master/slave configuration.

The three signal wires hold a clock (SCK, often on the order of 10 MHz),
and parallel data lines with "Master Out, Slave In" (MOSI) or "Master In,
Slave Out" (MISO) signals.  (Other names are also used.)  There are four
clocking modes through which data is exchanged; mode-0 and mode-3 are most
commonly used.  Each clock cycle shifts data out and data in; the clock
doesn't cycle except when there is a data bit to shift.  Not all data bits
are used though; not every protocol uses those full duplex capabilities.

SPI masters use a fourth "chip select" line to activate a given SPI slave
device, so those three signal wires may be connected to several chips
in parallel.  All SPI slaves support chipselects; they are usually active
low signals, labeled nCSx for slave 'x' (e.g. nCS0).  Some devices have
other signals, often including an interrupt to the master.

Unlike serial busses like USB or SMBus, even low level protocols for
SPI slave functions are usually not interoperable between vendors
(except for commodities like SPI memory chips).

  - SPI may be used for request/response style device protocols, as with
    touchscreen sensors and memory chips.

  - It may also be used to stream data in either direction (half duplex),
    or both of them at the same time (full duplex).

  - Some devices may use eight bit words.  Others may use different word
    lengths, such as streams of 12-bit or 20-bit digital samples.

  - Words are usually sent with their most significant bit (MSB) first,
    but sometimes the least significant bit (LSB) goes first instead.

  - Sometimes SPI is used to daisy-chain devices, like shift registers.

In the same way, SPI slaves will only rarely support any kind of automatic
discovery/enumeration protocol.  The tree of slave devices accessible from
a given SPI master will normally be set up manually, with configuration
tables.

SPI is only one of the names used by such four-wire protocols, and
most controllers have no problem handling "MicroWire" (think of it as
half-duplex SPI, for request/response protocols), SSP ("Synchronous
Serial Protocol"), PSP ("Programmable Serial Protocol"), and other
related protocols.

Some chips eliminate a signal line by combining MOSI and MISO, and
limiting themselves to half-duplex at the hardware level.  In fact
some SPI chips have this signal mode as a strapping option.  These
can be accessed using the same programming interface as SPI, but of
course they won't handle full duplex transfers.  You may find such
chips described as using "three wire" signaling: SCK, data, nCSx.
(That data line is sometimes called MOMI or SISO.)

Microcontrollers often support both master and slave sides of the SPI
protocol.  This document (and Linux) supports both the master and slave
sides of SPI interactions.

Who uses it?  On what kinds of systems?
---------------------------------------
Linux developers using SPI are probably writing device drivers for embedded
systems boards.  SPI is used to control external chips, and it is also a
protocol supported by every MMC or SD memory card.  (The older "DataFlash"
cards, predating MMC cards but using the same connectors and card shape,
support only SPI.)  Some PC hardware uses SPI flash for BIOS code.

SPI slave chips range from digital/analog converters used for analog
sensors and codecs, to memory, to peripherals like USB controllers
or Ethernet adapters; and more.

Most systems using SPI will integrate a few devices on a mainboard.
Some provide SPI links on expansion connectors; in cases where no
dedicated SPI controller exists, GPIO pins can be used to create a
low speed "bitbanging" adapter.  Very few systems will "hotplug" an SPI
controller; the reasons to use SPI focus on low cost and simple operation,
and if dynamic reconfiguration is important, USB will often be a more
appropriate low-pincount peripheral bus.

Many microcontrollers that can run Linux integrate one or more I/O
interfaces with SPI modes.  Given SPI support, they could use MMC or SD
cards without needing a special purpose MMC/SD/SDIO controller.

I'm confused.  What are these four SPI "clock modes"?
-----------------------------------------------------
It's easy to be confused here, and the vendor documentation you'll
find isn't necessarily helpful.  The four modes combine two mode bits:

 - CPOL indicates the initial clock polarity.  CPOL=0 means the
   clock starts low, so the first (leading) edge is rising, and
   the second (trailing) edge is falling.  CPOL=1 means the clock
   starts high, so the first (leading) edge is falling.

 - CPHA indicates the clock phase used to sample data; CPHA=0 says
   sample on the leading edge, CPHA=1 means the trailing edge.

   Since the signal needs to stablize before it's sampled, CPHA=0
   implies that its data is written half a clock before the first
   clock edge.  The chipselect may have made it become available.

Chip specs won't always say "uses SPI mode X" in as many words,
but their timing diagrams will make the CPOL and CPHA modes clear.

In the SPI mode number, CPOL is the high order bit and CPHA is the
low order bit.  So when a chip's timing diagram shows the clock
starting low (CPOL=0) and data stabilized for sampling during the
trailing clock edge (CPHA=1), that's SPI mode 1.

Note that the clock mode is relevant as soon as the chipselect goes
active.  So the master must set the clock to inactive before selecting
a slave, and the slave can tell the chosen polarity by sampling the
clock level when its select line goes active.  That's why many devices
support for example both modes 0 and 3:  they don't care about polarity,
and always clock data in/out on rising clock edges.

How do these driver programming interfaces work?
------------------------------------------------
The <linux/spi/spi.h> header file includes kerneldoc, as does the
main source code, and you should certainly read that chapter of the
kernel API document.  This is just an overview, so you get the big
picture before those details.

SPI requests always go into I/O queues.  Requests for a given SPI device
are always executed in FIFO order, and complete asynchronously through
completion callbacks.  There are also some simple synchronous wrappers
for those calls, including ones for common transaction types like writing
a command and then reading its response.

There are two types of SPI driver, here called:

  Controller drivers ...
        controllers may be built into System-On-Chip
	processors, and often support both Master and Slave roles.
	These drivers touch hardware registers and may use DMA.
	Or they can be PIO bitbangers, needing just GPIO pins.

  Protocol drivers ...
        these pass messages through the controller
	driver to communicate with a Slave or Master device on the
	other side of an SPI link.

So for example one protocol driver might talk to the MTD layer to export
data to filesystems stored on SPI flash like DataFlash; and others might
control audio interfaces, present touchscreen sensors as input interfaces,
or monitor temperature and voltage levels during industrial processing.
And those might all be sharing the same controller driver.

A "struct spi_device" encapsulates the controller-side interface between
those two types of drivers.

There is a minimal core of SPI programming interfaces, focussing on
using the driver model to connect controller and protocol drivers using
device tables provided by board specific initialization code.  SPI
shows up in sysfs in several locations::

   /sys/devices/.../CTLR ... physical node for a given SPI controller

   /sys/devices/.../CTLR/spiB.C ... spi_device on bus "B",
	chipselect C, accessed through CTLR.

   /sys/bus/spi/devices/spiB.C ... symlink to that physical
	.../CTLR/spiB.C device

   /sys/devices/.../CTLR/spiB.C/modalias ... identifies the driver
	that should be used with this device (for hotplug/coldplug)

   /sys/bus/spi/drivers/D ... driver for one or more spi*.* devices

   /sys/class/spi_master/spiB ... symlink (or actual device node) to
	a logical node which could hold class related state for the SPI
	master controller managing bus "B".  All spiB.* devices share one
	physical SPI bus segment, with SCLK, MOSI, and MISO.

   /sys/devices/.../CTLR/slave ... virtual file for (un)registering the
	slave device for an SPI slave controller.
	Writing the driver name of an SPI slave handler to this file
	registers the slave device; writing "(null)" unregisters the slave
	device.
	Reading from this file shows the name of the slave device ("(null)"
	if not registered).

   /sys/class/spi_slave/spiB ... symlink (or actual device node) to
	a logical node which could hold class related state for the SPI
	slave controller on bus "B".  When registered, a single spiB.*
	device is present here, possible sharing the physical SPI bus
	segment with other SPI slave devices.

Note that the actual location of the controller's class state depends
on whether you enabled CONFIG_SYSFS_DEPRECATED or not.  At this time,
the only class-specific state is the bus number ("B" in "spiB"), so
those /sys/class entries are only useful to quickly identify busses.

How does board-specific init code declare SPI devices?
------------------------------------------------------
Linux needs several kinds of information to properly configure SPI devices.
That information is normally provided by board-specific code, even for
chips that do support some of automated discovery/enumeration.

Declare Controllers
^^^^^^^^^^^^^^^^^^^

The first kind of information is a list of what SPI controllers exist.
For System-on-Chip (SOC) based boards, these will usually be platform
devices, and the controller may need some platform_data in order to
operate properly.  The "struct platform_device" will include resources
like the physical address of the controller's first register and its IRQ.

Platforms will often abstract the "register SPI controller" operation,
maybe coupling it with code to initialize pin configurations, so that
the arch/.../mach-*/board-*.c files for several boards can all share the
same basic controller setup code.  This is because most SOCs have several
SPI-capable controllers, and only the ones actually usable on a given
board should normally be set up and registered.

So for example arch/.../mach-*/board-*.c files might have code like::

	#include <mach/spi.h>	/* for mysoc_spi_data */

	/* if your mach-* infrastructure doesn't support kernels that can
	 * run on multiple boards, pdata wouldn't benefit from "__init".
	 */
	static struct mysoc_spi_data pdata __initdata = { ... };

	static __init board_init(void)
	{
		...
		/* this board only uses SPI controller #2 */
		mysoc_register_spi(2, &pdata);
		...
	}

And SOC-specific utility code might look something like::

	#include <mach/spi.h>

	static struct platform_device spi2 = { ... };

	void mysoc_register_spi(unsigned n, struct mysoc_spi_data *pdata)
	{
		struct mysoc_spi_data *pdata2;

		pdata2 = kmalloc(sizeof *pdata2, GFP_KERNEL);
		*pdata2 = pdata;
		...
		if (n == 2) {
			spi2->dev.platform_data = pdata2;
			register_platform_device(&spi2);

			/* also: set up pin modes so the spi2 signals are
			 * visible on the relevant pins ... bootloaders on
			 * production boards may already have done this, but
			 * developer boards will often need Linux to do it.
			 */
		}
		...
	}

Notice how the platform_data for boards may be different, even if the
same SOC controller is used.  For example, on one board SPI might use
an external clock, where another derives the SPI clock from current
settings of some master clock.

Declare Slave Devices
^^^^^^^^^^^^^^^^^^^^^

The second kind of information is a list of what SPI slave devices exist
on the target board, often with some board-specific data needed for the
driver to work correctly.

Normally your arch/.../mach-*/board-*.c files would provide a small table
listing the SPI devices on each board.  (This would typically be only a
small handful.)  That might look like::

	static struct ads7846_platform_data ads_info = {
		.vref_delay_usecs	= 100,
		.x_plate_ohms		= 580,
		.y_plate_ohms		= 410,
	};

	static struct spi_board_info spi_board_info[] __initdata = {
	{
		.modalias	= "ads7846",
		.platform_data	= &ads_info,
		.mode		= SPI_MODE_0,
		.irq		= GPIO_IRQ(31),
		.max_speed_hz	= 120000 /* max sample rate at 3V */ * 16,
		.bus_num	= 1,
		.chip_select	= 0,
	},
	};

Again, notice how board-specific information is provided; each chip may need
several types.  This example shows generic constraints like the fastest SPI
clock to allow (a function of board voltage in this case) or how an IRQ pin
is wired, plus chip-specific constraints like an important delay that's
changed by the capacitance at one pin.

(There's also "controller_data", information that may be useful to the
controller driver.  An example would be peripheral-specific DMA tuning
data or chipselect callbacks.  This is stored in spi_device later.)

The board_info should provide enough information to let the system work
without the chip's driver being loaded.  The most troublesome aspect of
that is likely the SPI_CS_HIGH bit in the spi_device.mode field, since
sharing a bus with a device that interprets chipselect "backwards" is
not possible until the infrastructure knows how to deselect it.

Then your board initialization code would register that table with the SPI
infrastructure, so that it's available later when the SPI master controller
driver is registered::

	spi_register_board_info(spi_board_info, ARRAY_SIZE(spi_board_info));

Like with other static board-specific setup, you won't unregister those.

The widely used "card" style computers bundle memory, cpu, and little else
onto a card that's maybe just thirty square centimeters.  On such systems,
your ``arch/.../mach-.../board-*.c`` file would primarily provide information
about the devices on the mainboard into which such a card is plugged.  That
certainly includes SPI devices hooked up through the card connectors!

Non-static Configurations
^^^^^^^^^^^^^^^^^^^^^^^^^

When Linux includes support for MMC/SD/SDIO/DataFlash cards through SPI, those
configurations will also be dynamic.  Fortunately, such devices all support
basic device identification probes, so they should hotplug normally.

How do I write an "SPI Protocol Driver"?
----------------------------------------
Most SPI drivers are currently kernel drivers, but there's also support
for userspace drivers.  Here we talk only about kernel drivers.

SPI protocol drivers somewhat resemble platform device drivers::

	static struct spi_driver CHIP_driver = {
		.driver = {
			.name		= "CHIP",
			.owner		= THIS_MODULE,
			.pm		= &CHIP_pm_ops,
		},

		.probe		= CHIP_probe,
		.remove		= CHIP_remove,
	};

The driver core will automatically attempt to bind this driver to any SPI
device whose board_info gave a modalias of "CHIP".  Your probe() code
might look like this unless you're creating a device which is managing
a bus (appearing under /sys/class/spi_master).

::

	static int CHIP_probe(struct spi_device *spi)
	{
		struct CHIP			*chip;
		struct CHIP_platform_data	*pdata;

		/* assuming the driver requires board-specific data: */
		pdata = &spi->dev.platform_data;
		if (!pdata)
			return -ENODEV;

		/* get memory for driver's per-chip state */
		chip = kzalloc(sizeof *chip, GFP_KERNEL);
		if (!chip)
			return -ENOMEM;
		spi_set_drvdata(spi, chip);

		... etc
		return 0;
	}

As soon as it enters probe(), the driver may issue I/O requests to
the SPI device using "struct spi_message".  When remove() returns,
or after probe() fails, the driver guarantees that it won't submit
any more such messages.

  - An spi_message is a sequence of protocol operations, executed
    as one atomic sequence.  SPI driver controls include:

      + when bidirectional reads and writes start ... by how its
        sequence of spi_transfer requests is arranged;

      + which I/O buffers are used ... each spi_transfer wraps a
        buffer for each transfer direction, supporting full duplex
        (two pointers, maybe the same one in both cases) and half
        duplex (one pointer is NULL) transfers;

      + optionally defining short delays after transfers ... using
        the spi_transfer.delay.value setting (this delay can be the
        only protocol effect, if the buffer length is zero) ...
        when specifying this delay the default spi_transfer.delay.unit
        is microseconds, however this can be adjusted to clock cycles
        or nanoseconds if needed;

      + whether the chipselect becomes inactive after a transfer and
        any delay ... by using the spi_transfer.cs_change flag;

      + hinting whether the next message is likely to go to this same
        device ... using the spi_transfer.cs_change flag on the last
	transfer in that atomic group, and potentially saving costs
	for chip deselect and select operations.

  - Follow standard kernel rules, and provide DMA-safe buffers in
    your messages.  That way controller drivers using DMA aren't forced
    to make extra copies unless the hardware requires it (e.g. working
    around hardware errata that force the use of bounce buffering).

    If standard dma_map_single() handling of these buffers is inappropriate,
    you can use spi_message.is_dma_mapped to tell the controller driver
    that you've already provided the relevant DMA addresses.

  - The basic I/O primitive is spi_async().  Async requests may be
    issued in any context (irq handler, task, etc) and completion
    is reported using a callback provided with the message.
    After any detected error, the chip is deselected and processing
    of that spi_message is aborted.

  - There are also synchronous wrappers like spi_sync(), and wrappers
    like spi_read(), spi_write(), and spi_write_then_read().  These
    may be issued only in contexts that may sleep, and they're all
    clean (and small, and "optional") layers over spi_async().

  - The spi_write_then_read() call, and convenience wrappers around
    it, should only be used with small amounts of data where the
    cost of an extra copy may be ignored.  It's designed to support
    common RPC-style requests, such as writing an eight bit command
    and reading a sixteen bit response -- spi_w8r16() being one its
    wrappers, doing exactly that.

Some drivers may need to modify spi_device characteristics like the
transfer mode, wordsize, or clock rate.  This is done with spi_setup(),
which would normally be called from probe() before the first I/O is
done to the device.  However, that can also be called at any time
that no message is pending for that device.

While "spi_device" would be the bottom boundary of the driver, the
upper boundaries might include sysfs (especially for sensor readings),
the input layer, ALSA, networking, MTD, the character device framework,
or other Linux subsystems.

Note that there are two types of memory your driver must manage as part
of interacting with SPI devices.

  - I/O buffers use the usual Linux rules, and must be DMA-safe.
    You'd normally allocate them from the heap or free page pool.
    Don't use the stack, or anything that's declared "static".

  - The spi_message and spi_transfer metadata used to glue those
    I/O buffers into a group of protocol transactions.  These can
    be allocated anywhere it's convenient, including as part of
    other allocate-once driver data structures.  Zero-init these.

If you like, spi_message_alloc() and spi_message_free() convenience
routines are available to allocate and zero-initialize an spi_message
with several transfers.

How do I write an "SPI Master Controller Driver"?
-------------------------------------------------
An SPI controller will probably be registered on the platform_bus; write
a driver to bind to the device, whichever bus is involved.

The main task of this type of driver is to provide an "spi_master".
Use spi_alloc_master() to allocate the master, and spi_master_get_devdata()
to get the driver-private data allocated for that device.

::

	struct spi_master	*master;
	struct CONTROLLER	*c;

	master = spi_alloc_master(dev, sizeof *c);
	if (!master)
		return -ENODEV;

	c = spi_master_get_devdata(master);

The driver will initialize the fields of that spi_master, including the
bus number (maybe the same as the platform device ID) and three methods
used to interact with the SPI core and SPI protocol drivers.  It will
also initialize its own internal state.  (See below about bus numbering
and those methods.)

After you initialize the spi_master, then use spi_register_master() to
publish it to the rest of the system. At that time, device nodes for the
controller and any predeclared spi devices will be made available, and
the driver model core will take care of binding them to drivers.

If you need to remove your SPI controller driver, spi_unregister_master()
will reverse the effect of spi_register_master().

Bus Numbering
^^^^^^^^^^^^^

Bus numbering is important, since that's how Linux identifies a given
SPI bus (shared SCK, MOSI, MISO).  Valid bus numbers start at zero.  On
SOC systems, the bus numbers should match the numbers defined by the chip
manufacturer.  For example, hardware controller SPI2 would be bus number 2,
and spi_board_info for devices connected to it would use that number.

If you don't have such hardware-assigned bus number, and for some reason
you can't just assign them, then provide a negative bus number.  That will
then be replaced by a dynamically assigned number. You'd then need to treat
this as a non-static configuration (see above).

SPI Master Methods
^^^^^^^^^^^^^^^^^^

``master->setup(struct spi_device *spi)``
	This sets up the device clock rate, SPI mode, and word sizes.
	Drivers may change the defaults provided by board_info, and then
	call spi_setup(spi) to invoke this routine.  It may sleep.

	Unless each SPI slave has its own configuration registers, don't
	change them right away ... otherwise drivers could corrupt I/O
	that's in progress for other SPI devices.

	.. note::

		BUG ALERT:  for some reason the first version of
		many spi_master drivers seems to get this wrong.
		When you code setup(), ASSUME that the controller
		is actively processing transfers for another device.

``master->cleanup(struct spi_device *spi)``
	Your controller driver may use spi_device.controller_state to hold
	state it dynamically associates with that device.  If you do that,
	be sure to provide the cleanup() method to free that state.

``master->prepare_transfer_hardware(struct spi_master *master)``
	This will be called by the queue mechanism to signal to the driver
	that a message is coming in soon, so the subsystem requests the
	driver to prepare the transfer hardware by issuing this call.
	This may sleep.

``master->unprepare_transfer_hardware(struct spi_master *master)``
	This will be called by the queue mechanism to signal to the driver
	that there are no more messages pending in the queue and it may
	relax the hardware (e.g. by power management calls). This may sleep.

``master->transfer_one_message(struct spi_master *master, struct spi_message *mesg)``
	The subsystem calls the driver to transfer a single message while
	queuing transfers that arrive in the meantime. When the driver is
	finished with this message, it must call
	spi_finalize_current_message() so the subsystem can issue the next
	message. This may sleep.

``master->transfer_one(struct spi_master *master, struct spi_device *spi, struct spi_transfer *transfer)``
	The subsystem calls the driver to transfer a single transfer while
	queuing transfers that arrive in the meantime. When the driver is
	finished with this transfer, it must call
	spi_finalize_current_transfer() so the subsystem can issue the next
	transfer. This may sleep. Note: transfer_one and transfer_one_message
	are mutually exclusive; when both are set, the generic subsystem does
	not call your transfer_one callback.

	Return values:

	* negative errno: error
	* 0: transfer is finished
	* 1: transfer is still in progress

``master->set_cs_timing(struct spi_device *spi, u8 setup_clk_cycles, u8 hold_clk_cycles, u8 inactive_clk_cycles)``
	This method allows SPI client drivers to request SPI master controller
	for configuring device specific CS setup, hold and inactive timing
	requirements.

Deprecated Methods
^^^^^^^^^^^^^^^^^^

``master->transfer(struct spi_device *spi, struct spi_message *message)``
	This must not sleep. Its responsibility is to arrange that the
	transfer happens and its complete() callback is issued. The two
	will normally happen later, after other transfers complete, and
	if the controller is idle it will need to be kickstarted. This
	method is not used on queued controllers and must be NULL if
	transfer_one_message() and (un)prepare_transfer_hardware() are
	implemented.

SPI Message Queue
^^^^^^^^^^^^^^^^^

If you are happy with the standard queueing mechanism provided by the
SPI subsystem, just implement the queued methods specified above. Using
the message queue has the upside of centralizing a lot of code and
providing pure process-context execution of methods. The message queue
can also be elevated to realtime priority on high-priority SPI traffic.

Unless the queueing mechanism in the SPI subsystem is selected, the bulk
of the driver will be managing the I/O queue fed by the now deprecated
function transfer().

That queue could be purely conceptual.  For example, a driver used only
for low-frequency sensor access might be fine using synchronous PIO.

But the queue will probably be very real, using message->queue, PIO,
often DMA (especially if the root filesystem is in SPI flash), and
execution contexts like IRQ handlers, tasklets, or workqueues (such
as keventd).  Your driver can be as fancy, or as simple, as you need.
Such a transfer() method would normally just add the message to a
queue, and then start some asynchronous transfer engine (unless it's
already running).

THANKS TO
---------
Contributors to Linux-SPI discussions include (in alphabetical order,
by last name):

- Mark Brown
- David Brownell
- Russell King
- Grant Likely
- Dmitry Pervushin
- Stephen Street
- Mark Underwood
- Andrew Victor
- Linus Walleij
- Vitaly Wool