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# SPDX-License-Identifier: GPL-2.0+
# Copyright (C) 2017 Google, Inc
# Written by Simon Glass <>
"""Device tree to platform data class
This supports converting device tree data to C structures definitions and
static data.
import collections
import copy
import sys
import fdt
import fdt_util
# When we see these properties we ignore them - i.e. do not create a structure member
# C type declarations for the tyues we support
fdt.TYPE_INT: 'fdt32_t',
fdt.TYPE_BYTE: 'unsigned char',
fdt.TYPE_STRING: 'const char *',
fdt.TYPE_BOOL: 'bool',
fdt.TYPE_INT64: 'fdt64_t',
VAL_PREFIX = 'dtv_'
# This holds information about a property which includes phandles.
# max_args: integer: Maximum number or arguments that any phandle uses (int).
# args: Number of args for each phandle in the property. The total number of
# phandles is len(args). This is a list of integers.
PhandleInfo = collections.namedtuple('PhandleInfo', ['max_args', 'args'])
def conv_name_to_c(name):
"""Convert a device-tree name to a C identifier
This uses multiple replace() calls instead of re.sub() since it is faster
(400ms for 1m calls versus 1000ms for the 're' version).
name: Name to convert
String containing the C version of this name
new = name.replace('@', '_at_')
new = new.replace('-', '_')
new = new.replace(',', '_')
new = new.replace('.', '_')
return new
def tab_to(num_tabs, line):
"""Append tabs to a line of text to reach a tab stop.
num_tabs: Tab stop to obtain (0 = column 0, 1 = column 8, etc.)
line: Line of text to append to
line with the correct number of tabs appeneded. If the line already
extends past that tab stop then a single space is appended.
if len(line) >= num_tabs * 8:
return line + ' '
return line + '\t' * (num_tabs - len(line) // 8)
def get_value(ftype, 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'
type: Data type (fdt_util)
value: Data value, as a string of bytes
if ftype == fdt.TYPE_INT:
return '%#x' % fdt_util.fdt32_to_cpu(value)
elif ftype == fdt.TYPE_BYTE:
return '%#x' % ord(value[0])
elif ftype == fdt.TYPE_STRING:
return '"%s"' % value
elif ftype == fdt.TYPE_BOOL:
return 'true'
elif ftype == fdt.TYPE_INT64:
return '%#x' % value
def get_compat_name(node):
"""Get a node's first compatible string as a C identifier
node: Node object to check
C identifier for the first compatible string
List of C identifiers for all the other compatible strings
(possibly empty)
compat = node.props['compatible'].value
aliases = []
if isinstance(compat, list):
compat, aliases = compat[0], compat[1:]
return conv_name_to_c(compat), [conv_name_to_c(a) for a in aliases]
class DtbPlatdata(object):
"""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.
_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
_include_disabled: true to include nodes marked status = "disabled"
_outfile: The current output file (sys.stdout or a real file)
_lines: Stashed list of output lines for outputting in the future
def __init__(self, dtb_fname, include_disabled):
self._fdt = None
self._dtb_fname = dtb_fname
self._valid_nodes = None
self._include_disabled = include_disabled
self._outfile = None
self._lines = []
self._aliases = {}
def setup_output(self, fname):
"""Set up the output destination
Once this is done, future calls to self.out() will output to this
fname: Filename to send output to, or '-' for stdout
if fname == '-':
self._outfile = sys.stdout
self._outfile = open(fname, 'w')
def out(self, line):
"""Output a string to the output file
line: String to output
def buf(self, line):
"""Buffer up a string to send later
line: String to add to our 'buffer' list
def get_buf(self):
"""Get the contents of the output buffer, and clear it
The output buffer, which is then cleared for future use
lines = self._lines
self._lines = []
return lines
def out_header(self):
"""Output a message indicating that this is an auto-generated file"""
* This file was generated by dtoc from a .dtb (device tree binary) file.
def get_phandle_argc(self, prop, node_name):
"""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.
prop: Prop object to check
Number of argument cells is this is a phandle, else None
if in ['clocks']:
if not isinstance(prop.value, list):
prop.value = [prop.value]
val = prop.value
i = 0
max_args = 0
args = []
while i < len(val):
phandle = fdt_util.fdt32_to_cpu(val[i])
# If we get to the end of the list, stop. This can happen
# since some nodes have more phandles in the list than others,
# but we allocate enough space for the largest list. So those
# nodes with shorter lists end up with zeroes at the end.
if not phandle:
target = self._fdt.phandle_to_node.get(phandle)
if not target:
raise ValueError("Cannot parse '%s' in node '%s'" %
(, node_name))
prop_name = '#clock-cells'
cells = target.props.get(prop_name)
if not cells:
raise ValueError("Node '%s' has no '%s' property" %
(, prop_name))
num_args = fdt_util.fdt32_to_cpu(cells.value)
max_args = max(max_args, num_args)
i += 1 + num_args
return PhandleInfo(max_args, args)
return None
def scan_dtb(self):
"""Scan the device tree to obtain a tree of nodes 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.FdtScan(self._dtb_fname)
def scan_node(self, root):
"""Scan a node and subnodes to build a tree of node and phandle info
This adds each node to self._valid_nodes.
root: Root node for scan
for node in root.subnodes:
if 'compatible' in node.props:
status = node.props.get('status')
if (not self._include_disabled and not status or
status.value != 'disabled'):
# recurse to handle any subnodes
def scan_tree(self):
"""Scan the device tree for useful information
This fills in the following properties:
_valid_nodes: A list of nodes we wish to consider include in the
platform data
self._valid_nodes = []
return self.scan_node(self._fdt.GetRoot())
def get_num_cells(node):
"""Get the number of cells in addresses and sizes for this node
node: Node to check
Number of address cells for this node
Number of size cells for this node
parent = node.parent
na, ns = 2, 2
if parent:
na_prop = parent.props.get('#address-cells')
ns_prop = parent.props.get('#size-cells')
if na_prop:
na = fdt_util.fdt32_to_cpu(na_prop.value)
if ns_prop:
ns = fdt_util.fdt32_to_cpu(ns_prop.value)
return na, ns
def scan_reg_sizes(self):
"""Scan for 64-bit 'reg' properties and update the values
This finds 'reg' properties with 64-bit data and converts the value to
an array of 64-values. This allows it to be output in a way that the
C code can read.
for node in self._valid_nodes:
reg = node.props.get('reg')
if not reg:
na, ns = self.get_num_cells(node)
total = na + ns
if reg.type != fdt.TYPE_INT:
raise ValueError("Node '%s' reg property is not an int" %
if len(reg.value) % total:
raise ValueError("Node '%s' reg property has %d cells "
'which is not a multiple of na + ns = %d + %d)' %
(, len(reg.value), na, ns)) = na
reg.ns = ns
if na != 1 or ns != 1:
reg.type = fdt.TYPE_INT64
i = 0
new_value = []
val = reg.value
if not isinstance(val, list):
val = [val]
while i < len(val):
addr = fdt_util.fdt_cells_to_cpu(val[i:],
i += na
size = fdt_util.fdt_cells_to_cpu(val[i:], reg.ns)
i += ns
new_value += [addr, size]
reg.value = new_value
def scan_structs(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, _ = get_compat_name(node)
fields = {}
# Get a list of all the valid properties in this node.
for name, prop in node.props.items():
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.items():
oldprop = struct.get(name)
if oldprop:
struct[name] = prop
# Otherwise store this as a new struct.
structs[node_name] = fields
upto = 0
for node in self._valid_nodes:
node_name, _ = get_compat_name(node)
struct = structs[node_name]
for name, prop in node.props.items():
if name not in PROP_IGNORE_LIST and name[0] != '#':
upto += 1
struct_name, aliases = get_compat_name(node)
for alias in aliases:
self._aliases[alias] = struct_name
return structs
def scan_phandles(self):
"""Figure out what phandles each node uses
We need to be careful when outputing nodes that use phandles since
they must come after the declaration of the phandles in the C file.
Otherwise we get a compiler error since the phandle struct is not yet
This function adds to each node a list of phandle nodes that the node
depends on. This allows us to output things in the right order.
for node in self._valid_nodes:
node.phandles = set()
for pname, prop in node.props.items():
if pname in PROP_IGNORE_LIST or pname[0] == '#':
info = self.get_phandle_argc(prop,
if info:
# Process the list as pairs of (phandle, id)
pos = 0
for args in info.args:
phandle_cell = prop.value[pos]
phandle = fdt_util.fdt32_to_cpu(phandle_cell)
target_node = self._fdt.phandle_to_node[phandle]
pos += 1 + args
def generate_structs(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 <linux/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]
info = self.get_phandle_argc(prop, structs[name])
if info:
# For phandles, include a reference to the target
struct_name = 'struct phandle_%d_arg' % info.max_args
self.out('\t%s%s[%d]' % (tab_to(2, struct_name),
ptype = TYPE_NAMES[prop.type]
self.out('\t%s%s' % (tab_to(2, ptype),
if isinstance(prop.value, list):
self.out('[%d]' % len(prop.value))
for alias, struct_name in self._aliases.iteritems():
self.out('#define %s%s %s%s\n'% (STRUCT_PREFIX, alias,
STRUCT_PREFIX, struct_name))
def output_node(self, node):
"""Output the C code for a node
node: node to output
struct_name, _ = get_compat_name(node)
var_name = conv_name_to_c(
self.buf('static const struct %s%s %s%s = {\n' %
(STRUCT_PREFIX, struct_name, VAL_PREFIX, var_name))
for pname, prop in node.props.items():
if pname in PROP_IGNORE_LIST or pname[0] == '#':
member_name = conv_name_to_c(
self.buf('\t%s= ' % tab_to(3, '.' + member_name))
# Special handling for lists
if isinstance(prop.value, list):
vals = []
# For phandles, output a reference to the platform data
# of the target node.
info = self.get_phandle_argc(prop,
if info:
# Process the list as pairs of (phandle, id)
pos = 0
for args in info.args:
phandle_cell = prop.value[pos]
phandle = fdt_util.fdt32_to_cpu(phandle_cell)
target_node = self._fdt.phandle_to_node[phandle]
name = conv_name_to_c(
arg_values = []
for i in range(args):
arg_values.append(str(fdt_util.fdt32_to_cpu(prop.value[pos + 1 + i])))
pos += 1 + args
vals.append('\t{&%s%s, {%s}}' % (VAL_PREFIX, name,
', '.join(arg_values)))
for val in vals:
self.buf('\n\t\t%s,' % val)
for val in prop.value:
vals.append(get_value(prop.type, val))
# Put 8 values per line to avoid very long lines.
for i in xrange(0, len(vals), 8):
if i:
self.buf(', '.join(vals[i:i + 8]))
self.buf(get_value(prop.type, prop.value))
# Add a device declaration
self.buf('U_BOOT_DEVICE(%s) = {\n' % var_name)
self.buf('\\t\t= "%s",\n' % struct_name)
self.buf('\t.platdata\t= &%s%s,\n' % (VAL_PREFIX, var_name))
self.buf('\t.platdata_size\t= sizeof(%s%s),\n' % (VAL_PREFIX, var_name))
def generate_tables(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. Where a node has
multiple compatible strings, a #define is used to make them equivalent.
See the documentation in doc/driver-model/of-plat.txt for more
self.out('#include <common.h>\n')
self.out('#include <dm.h>\n')
self.out('#include <dt-structs.h>\n')
nodes_to_output = list(self._valid_nodes)
# Keep outputing nodes until there is none left
while nodes_to_output:
node = nodes_to_output[0]
# Output all the node's dependencies first
for req_node in node.phandles:
if req_node in nodes_to_output:
def run_steps(args, dtb_file, include_disabled, output):
"""Run all the steps of the dtoc tool
args: List of non-option arguments provided to the problem
dtb_file: Filename of dtb file to process
include_disabled: True to include disabled nodes
output: Name of output file
if not args:
raise ValueError('Please specify a command: struct, platdata')
plat = DtbPlatdata(dtb_file, include_disabled)
structs = plat.scan_structs()
for cmd in args[0].split(','):
if cmd == 'struct':
elif cmd == 'platdata':
raise ValueError("Unknown command '%s': (use: struct, platdata)" %