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libfdt: Add fdt_next_subnode() to permit easy subnode iteration

Iterating through subnodes with libfdt is a little painful to write as we
need something like this:

for (depth = 0, count = 0,
	offset = fdt_next_node(fdt, parent_offset, &depth);
     (offset >= 0) && (depth > 0);
     offset = fdt_next_node(fdt, offset, &depth)) {
	if (depth == 1) {
		/* code body */
	}
}

Using fdt_next_subnode() we can instead write this, which is shorter and
easier to get right:

for (offset = fdt_first_subnode(fdt, parent_offset);
     offset >= 0;
     offset = fdt_next_subnode(fdt, offset)) {
	/* code body */
}

Also, it doesn't require two levels of indentation for the loop body.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
main
Simon Glass 12 years ago committed by Jon Loeliger
parent
commit
4e76ec796c
  1. 28
      libfdt/fdt.c
  2. 22
      libfdt/libfdt.h
  3. 3
      tests/Makefile.tests
  4. 3
      tests/run_tests.sh
  5. 94
      tests/subnode_iterate.c
  6. 44
      tests/subnode_iterate.dts

28
libfdt/fdt.c

@ -198,6 +198,34 @@ int fdt_next_node(const void *fdt, int offset, int *depth)
return offset; return offset;
} }


int fdt_first_subnode(const void *fdt, int offset)
{
int depth = 0;

offset = fdt_next_node(fdt, offset, &depth);
if (offset < 0 || depth != 1)
return -FDT_ERR_NOTFOUND;

return offset;
}

int fdt_next_subnode(const void *fdt, int offset)
{
int depth = 1;

/*
* With respect to the parent, the depth of the next subnode will be
* the same as the last.
*/
do {
offset = fdt_next_node(fdt, offset, &depth);
if (offset < 0 || depth < 1)
return -FDT_ERR_NOTFOUND;
} while (depth > 1);

return offset;
}

const char *_fdt_find_string(const char *strtab, int tabsize, const char *s) const char *_fdt_find_string(const char *strtab, int tabsize, const char *s)
{ {
int len = strlen(s) + 1; int len = strlen(s) + 1;

22
libfdt/libfdt.h

@ -136,6 +136,28 @@ uint32_t fdt_next_tag(const void *fdt, int offset, int *nextoffset);


int fdt_next_node(const void *fdt, int offset, int *depth); int fdt_next_node(const void *fdt, int offset, int *depth);


/**
* fdt_first_subnode() - get offset of first direct subnode
*
* @fdt: FDT blob
* @offset: Offset of node to check
* @return offset of first subnode, or -FDT_ERR_NOTFOUND if there is none
*/
int fdt_first_subnode(const void *fdt, int offset);

/**
* fdt_next_subnode() - get offset of next direct subnode
*
* After first calling fdt_first_subnode(), call this function repeatedly to
* get direct subnodes of a parent node.
*
* @fdt: FDT blob
* @offset: Offset of previous subnode
* @return offset of next subnode, or -FDT_ERR_NOTFOUND if there are no more
* subnodes
*/
int fdt_next_subnode(const void *fdt, int offset);

/**********************************************************************/ /**********************************************************************/
/* General functions */ /* General functions */
/**********************************************************************/ /**********************************************************************/

3
tests/Makefile.tests

@ -20,7 +20,8 @@ LIB_TESTS_L = get_mem_rsv \
dtb_reverse dtbs_equal_unordered \ dtb_reverse dtbs_equal_unordered \
add_subnode_with_nops path_offset_aliases \ add_subnode_with_nops path_offset_aliases \
utilfdt_test \ utilfdt_test \
integer-expressions integer-expressions \
subnode_iterate
LIB_TESTS = $(LIB_TESTS_L:%=$(TESTS_PREFIX)%) LIB_TESTS = $(LIB_TESTS_L:%=$(TESTS_PREFIX)%)


LIBTREE_TESTS_L = truncated_property LIBTREE_TESTS_L = truncated_property

3
tests/run_tests.sh

@ -241,6 +241,9 @@ libfdt_tests () {
tree1_tests_rw noppy.$basetree tree1_tests_rw noppy.$basetree
done done


run_dtc_test -I dts -O dtb -o subnode_iterate.dtb subnode_iterate.dts
run_test subnode_iterate subnode_iterate.dtb

# Tests for behaviour on various sorts of corrupted trees # Tests for behaviour on various sorts of corrupted trees
run_test truncated_property run_test truncated_property



94
tests/subnode_iterate.c

@ -0,0 +1,94 @@
/*
* libfdt - Flat Device Tree manipulation
* Tests that fdt_next_subnode() works as expected
*
* Copyright (C) 2013 Google, Inc
*
* Copyright (C) 2007 David Gibson, IBM Corporation.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>

#include <libfdt.h>

#include "tests.h"
#include "testdata.h"

static void test_node(void *fdt, int parent_offset)
{
fdt32_t subnodes;
const fdt32_t *prop;
int offset;
int count;
int len;

/* This property indicates the number of subnodes to expect */
prop = fdt_getprop(fdt, parent_offset, "subnodes", &len);
if (!prop || len != sizeof(fdt32_t)) {
FAIL("Missing/invalid subnodes property at '%s'",
fdt_get_name(fdt, parent_offset, NULL));
}
subnodes = cpu_to_fdt32(*prop);

count = 0;
for (offset = fdt_first_subnode(fdt, parent_offset);
offset >= 0;
offset = fdt_next_subnode(fdt, offset))
count++;

if (count != subnodes) {
FAIL("Node '%s': Expected %d subnodes, got %d\n",
fdt_get_name(fdt, parent_offset, NULL), subnodes,
count);
}
}

static void check_fdt_next_subnode(void *fdt)
{
int offset;
int count = 0;

for (offset = fdt_first_subnode(fdt, 0);
offset >= 0;
offset = fdt_next_subnode(fdt, offset)) {
test_node(fdt, offset);
count++;
}

if (count != 2)
FAIL("Expected %d tests, got %d\n", 2, count);
}

int main(int argc, char *argv[])
{
void *fdt;

test_init(argc, argv);
if (argc != 2)
CONFIG("Usage: %s <dtb file>", argv[0]);

fdt = load_blob(argv[1]);
if (!fdt)
FAIL("No device tree available");

check_fdt_next_subnode(fdt);

PASS();
}

44
tests/subnode_iterate.dts

@ -0,0 +1,44 @@
/dts-v1/;

/ {
#address-cells = <1>;
#size-cells = <0>;

test1 {
subnodes = <2>;
linux,phandle = <0x1>;
#address-cells = <1>;
#size-cells = <0>;
PowerPC,970@0 {
name = "PowerPC,970";
device_type = "cpu";
reg = <0x00000000>;
clock-frequency = <1600000000>;
timebase-frequency = <33333333>;
linux,boot-cpu;
i-cache-size = <65536>;
d-cache-size = <32768>;
another-sub-node {
should-be-ignored;
yet-another {
should-also-be-ignored;
};
};
};

PowerPC,970@1 {
name = "PowerPC,970";
device_type = "cpu";
reg = <0x00000001>;
clock-frequency = <1600000000>;
timebase-frequency = <33333333>;
i-cache-size = <65536>;
d-cache-size = <32768>;
};
};

test2 {
subnodes = <0>;
};
};

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