dm: Add a tool to generate C code from a device tree

This tool can produce C struct definitions and C platform data tables.
This is used to support the of-platdata feature.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/dtoc/dtoc

+dtoc.py
\ No newline at end of file

tools/dtoc/dtoc.py

+#!/usr/bin/python
+#
+# Copyright (C) 2016 Google, Inc
+# Written by Simon Glass <sjg@chromium.org>
+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+import copy
+from optparse import OptionError, OptionParser
+import os
+import sys
+
+import fdt_util
+
+# Bring in the patman libraries
+our_path = os.path.dirname(os.path.realpath(__file__))
+sys.path.append(os.path.join(our_path, '../patman'))
+
+# Bring in either the normal fdt library (which relies on libfdt) or the
+# fallback one (which uses fdtget and is slower). Both provide the same
+# interfface for this file to use.
+try:
+    from fdt import Fdt
+    import fdt
+    have_libfdt = True
+except ImportError:
+    have_libfdt = False
+    from fdt_fallback import Fdt
+    import fdt_fallback as fdt
+
+import struct
+
+# When we see these properties we ignore them - i.e. do not create a structure member
+PROP_IGNORE_LIST = [
+    '#address-cells',
+    '#gpio-cells',
+    '#size-cells',
+    'compatible',
+    'linux,phandle',
+    "status",
+    'phandle',
+]
+
+# C type declarations for the tyues we support
+TYPE_NAMES = {
+    fdt_util.TYPE_INT: 'fdt32_t',
+    fdt_util.TYPE_BYTE: 'unsigned char',
+    fdt_util.TYPE_STRING: 'const char *',
+    fdt_util.TYPE_BOOL: 'bool',
+};
+
+STRUCT_PREFIX = 'dtd_'
+VAL_PREFIX = 'dtv_'
+
+def Conv_name_to_c(name):
+    """Convert a device-tree name to a C identifier
+
+    Args:
+        name:   Name to convert
+    Return:
+        String containing the C version of this name
+    """
+    str = name.replace('@', '_at_')
+    str = str.replace('-', '_')
+    str = str.replace(',', '_')
+    str = str.replace('/', '__')
+    return str
+
+def TabTo(num_tabs, str):
+    if len(str) >= num_tabs * 8:
+        return str + ' '
+    return str + '\t' * (num_tabs - len(str) / 8)
+
+class DtbPlatdata:
+    """Provide a means to convert device tree binary data to platform data
+
+    The output of this process is C structures which can be used in space-
+    constrained encvironments where the ~3KB code overhead of device tree
+    code is not affordable.
+
+    Properties:
+        fdt: Fdt object, referencing the device tree
+        _dtb_fname: Filename of the input device tree binary file
+        _valid_nodes: A list of Node object with compatible strings
+        _options: Command-line options
+        _phandle_node: A dict of nodes indexed by phandle number (1, 2...)
+        _outfile: The current output file (sys.stdout or a real file)
+        _lines: Stashed list of output lines for outputting in the future
+        _phandle_node: A dict of Nodes indexed by phandle (an integer)
+    """
+    def __init__(self, dtb_fname, options):
+        self._dtb_fname = dtb_fname
+        self._valid_nodes = None
+        self._options = options
+        self._phandle_node = {}
+        self._outfile = None
+        self._lines = []
+
+    def SetupOutput(self, fname):
+        """Set up the output destination
+
+        Once this is done, future calls to self.Out() will output to this
+        file.
+
+        Args:
+            fname: Filename to send output to, or '-' for stdout
+        """
+        if fname == '-':
+            self._outfile = sys.stdout
+        else:
+            self._outfile = open(fname, 'w')
+
+    def Out(self, str):
+        """Output a string to the output file
+
+        Args:
+            str: String to output
+        """
+        self._outfile.write(str)
+
+    def Buf(self, str):
+        """Buffer up a string to send later
+
+        Args:
+            str: String to add to our 'buffer' list
+        """
+        self._lines.append(str)
+
+    def GetBuf(self):
+        """Get the contents of the output buffer, and clear it
+
+        Returns:
+            The output buffer, which is then cleared for future use
+        """
+        lines = self._lines
+        self._lines = []
+        return lines
+
+    def GetValue(self, type, value):
+        """Get a value as a C expression
+
+        For integers this returns a byte-swapped (little-endian) hex string
+        For bytes this returns a hex string, e.g. 0x12
+        For strings this returns a literal string enclosed in quotes
+        For booleans this return 'true'
+
+        Args:
+            type: Data type (fdt_util)
+            value: Data value, as a string of bytes
+        """
+        if type == fdt_util.TYPE_INT:
+            return '%#x' % fdt_util.fdt32_to_cpu(value)
+        elif type == fdt_util.TYPE_BYTE:
+            return '%#x' % ord(value[0])
+        elif type == fdt_util.TYPE_STRING:
+            return '"%s"' % value
+        elif type == fdt_util.TYPE_BOOL:
+            return 'true'
+
+    def GetCompatName(self, node):
+        """Get a node's first compatible string as a C identifier
+
+        Args:
+            node: Node object to check
+        Return:
+            C identifier for the first compatible string
+        """
+        compat = node.props['compatible'].value
+        if type(compat) == list:
+            compat = compat[0]
+        return Conv_name_to_c(compat)
+
+    def ScanDtb(self):
+        """Scan the device tree to obtain a tree of notes and properties
+
+        Once this is done, self.fdt.GetRoot() can be called to obtain the
+        device tree root node, and progress from there.
+        """
+        self.fdt = Fdt(self._dtb_fname)
+        self.fdt.Scan()
+
+    def ScanTree(self):
+        """Scan the device tree for useful information
+
+        This fills in the following properties:
+            _phandle_node: A dict of Nodes indexed by phandle (an integer)
+            _valid_nodes: A list of nodes we wish to consider include in the
+                platform data
+        """
+        node_list = []
+        self._phandle_node = {}
+        for node in self.fdt.GetRoot().subnodes:
+            if 'compatible' in node.props:
+                status = node.props.get('status')
+                if (not options.include_disabled and not status or
+                    status.value != 'disabled'):
+                    node_list.append(node)
+                    phandle_prop = node.props.get('phandle')
+                    if phandle_prop:
+                        phandle = phandle_prop.GetPhandle()
+                        self._phandle_node[phandle] = node
+
+        self._valid_nodes = node_list
+
+    def IsPhandle(self, prop):
+        """Check if a node contains phandles
+
+        We have no reliable way of detecting whether a node uses a phandle
+        or not. As an interim measure, use a list of known property names.
+
+        Args:
+            prop: Prop object to check
+        Return:
+            True if the object value contains phandles, else False
+        """
+        if prop.name in ['clocks']:
+            return True
+        return False
+
+    def ScanStructs(self):
+        """Scan the device tree building up the C structures we will use.
+
+        Build a dict keyed by C struct name containing a dict of Prop
+        object for each struct field (keyed by property name). Where the
+        same struct appears multiple times, try to use the 'widest'
+        property, i.e. the one with a type which can express all others.
+
+        Once the widest property is determined, all other properties are
+        updated to match that width.
+        """
+        structs = {}
+        for node in self._valid_nodes:
+            node_name = self.GetCompatName(node)
+            fields = {}
+
+            # Get a list of all the valid properties in this node.
+            for name, prop in node.props.iteritems():
+                if name not in PROP_IGNORE_LIST and name[0] != '#':
+                    fields[name] = copy.deepcopy(prop)
+
+            # If we've seen this node_name before, update the existing struct.
+            if node_name in structs:
+                struct = structs[node_name]
+                for name, prop in fields.iteritems():
+                    oldprop = struct.get(name)
+                    if oldprop:
+                        oldprop.Widen(prop)
+                    else:
+                        struct[name] = prop
+
+            # Otherwise store this as a new struct.
+            else:
+                structs[node_name] = fields
+
+        upto = 0
+        for node in self._valid_nodes:
+            node_name = self.GetCompatName(node)
+            struct = structs[node_name]
+            for name, prop in node.props.iteritems():
+                if name not in PROP_IGNORE_LIST and name[0] != '#':
+                    prop.Widen(struct[name])
+            upto += 1
+        return structs
+
+    def GenerateStructs(self, structs):
+        """Generate struct defintions for the platform data
+
+        This writes out the body of a header file consisting of structure
+        definitions for node in self._valid_nodes. See the documentation in
+        README.of-plat for more information.
+        """
+        self.Out('#include <stdbool.h>\n')
+        self.Out('#include <libfdt.h>\n')
+
+        # Output the struct definition
+        for name in sorted(structs):
+            self.Out('struct %s%s {\n' % (STRUCT_PREFIX, name));
+            for pname in sorted(structs[name]):
+                prop = structs[name][pname]
+                if self.IsPhandle(prop):
+                    # For phandles, include a reference to the target
+                    self.Out('\t%s%s[%d]' % (TabTo(2, 'struct phandle_2_cell'),
+                                             Conv_name_to_c(prop.name),
+                                             len(prop.value) / 2))
+                else:
+                    ptype = TYPE_NAMES[prop.type]
+                    self.Out('\t%s%s' % (TabTo(2, ptype),
+                                         Conv_name_to_c(prop.name)))
+                    if type(prop.value) == list:
+                        self.Out('[%d]' % len(prop.value))
+                self.Out(';\n')
+            self.Out('};\n')
+
+    def GenerateTables(self):
+        """Generate device defintions for the platform data
+
+        This writes out C platform data initialisation data and
+        U_BOOT_DEVICE() declarations for each valid node. See the
+        documentation in README.of-plat for more information.
+        """
+        self.Out('#include <common.h>\n')
+        self.Out('#include <dm.h>\n')
+        self.Out('#include <dt-structs.h>\n')
+        self.Out('\n')
+        node_txt_list = []
+        for node in self._valid_nodes:
+            struct_name = self.GetCompatName(node)
+            var_name = Conv_name_to_c(node.name)
+            self.Buf('static struct %s%s %s%s = {\n' %
+                (STRUCT_PREFIX, struct_name, VAL_PREFIX, var_name))
+            for pname, prop in node.props.iteritems():
+                if pname in PROP_IGNORE_LIST or pname[0] == '#':
+                    continue
+                ptype = TYPE_NAMES[prop.type]
+                member_name = Conv_name_to_c(prop.name)
+                self.Buf('\t%s= ' % TabTo(3, '.' + member_name))
+
+                # Special handling for lists
+                if type(prop.value) == list:
+                    self.Buf('{')
+                    vals = []
+                    # For phandles, output a reference to the platform data
+                    # of the target node.
+                    if self.IsPhandle(prop):
+                        # Process the list as pairs of (phandle, id)
+                        it = iter(prop.value)
+                        for phandle_cell, id_cell in zip(it, it):
+                            phandle = fdt_util.fdt32_to_cpu(phandle_cell)
+                            id = fdt_util.fdt32_to_cpu(id_cell)
+                            target_node = self._phandle_node[phandle]
+                            name = Conv_name_to_c(target_node.name)
+                            vals.append('{&%s%s, %d}' % (VAL_PREFIX, name, id))
+                    else:
+                        for val in prop.value:
+                            vals.append(self.GetValue(prop.type, val))
+                    self.Buf(', '.join(vals))
+                    self.Buf('}')
+                else:
+                    self.Buf(self.GetValue(prop.type, prop.value))
+                self.Buf(',\n')
+            self.Buf('};\n')
+
+            # Add a device declaration
+            self.Buf('U_BOOT_DEVICE(%s) = {\n' % var_name)
+            self.Buf('\t.name\t\t= "%s",\n' % struct_name)
+            self.Buf('\t.platdata\t= &%s%s,\n' % (VAL_PREFIX, var_name))
+            self.Buf('};\n')
+            self.Buf('\n')
+
+            # Output phandle target nodes first, since they may be referenced
+            # by others
+            if 'phandle' in node.props:
+                self.Out(''.join(self.GetBuf()))
+            else:
+                node_txt_list.append(self.GetBuf())
+
+        # Output all the nodes which are not phandle targets themselves, but
+        # may reference them. This avoids the need for forward declarations.
+        for node_txt in node_txt_list:
+            self.Out(''.join(node_txt))
+
+
+if __name__ != "__main__":
+    pass
+
+parser = OptionParser()
+parser.add_option('-d', '--dtb-file', action='store',
+                  help='Specify the .dtb input file')
+parser.add_option('--include-disabled', action='store_true',
+                  help='Include disabled nodes')
+parser.add_option('-o', '--output', action='store', default='-',
+                  help='Select output filename')
+(options, args) = parser.parse_args()
+
+if not args:
+    raise ValueError('Please specify a command: struct, platdata')
+
+plat = DtbPlatdata(options.dtb_file, options)
+plat.ScanDtb()
+plat.ScanTree()
+plat.SetupOutput(options.output)
+structs = plat.ScanStructs()
+
+for cmd in args[0].split(','):
+    if cmd == 'struct':
+        plat.GenerateStructs(structs)
+    elif cmd == 'platdata':
+        plat.GenerateTables()
+    else:
+        raise ValueError("Unknown command '%s': (use: struct, platdata)" % cmd)