[PATCH] libfdt: Add fdt_next_subnode() to permit easy subnode iteration
Simon Glass
sjg at chromium.org
Fri Apr 26 04:22:56 EST 2013
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 (depth = 0, offset = fdt_next_subnode(fdt, parent_offset, &depth);
offset >= 0;
offset = fdt_next_subnode(fdt, offset, &depth)) {
/* code body */
}
Also, it doesn't require two levels of indentation for the loop body.
Signed-off-by: Simon Glass <sjg at chromium.org>
---
libfdt/fdt.c | 12 ++++++
libfdt/libfdt.h | 17 +++++++++
tests/Makefile.tests | 3 +-
tests/run_tests.sh | 3 ++
tests/subnode_iterate.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++
tests/subnode_iterate.dts | 44 +++++++++++++++++++++
6 files changed, 175 insertions(+), 1 deletion(-)
create mode 100644 tests/subnode_iterate.c
create mode 100644 tests/subnode_iterate.dts
diff --git a/libfdt/fdt.c b/libfdt/fdt.c
index 57faba3..9433f38 100644
--- a/libfdt/fdt.c
+++ b/libfdt/fdt.c
@@ -198,6 +198,18 @@ int fdt_next_node(const void *fdt, int offset, int *depth)
return offset;
}
+int fdt_next_subnode(const void *fdt, int offset, int *depth)
+{
+ /* Loop until we find a direct child of the parent (depth == 1) */
+ 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)
{
int len = strlen(s) + 1;
diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
index 130789a..edd5488 100644
--- a/libfdt/libfdt.h
+++ b/libfdt/libfdt.h
@@ -136,6 +136,23 @@ uint32_t fdt_next_tag(const void *fdt, int offset, int *nextoffset);
int fdt_next_node(const void *fdt, int offset, int *depth);
+/**
+ * fdt_next_subnode() - get offset of next direct subnode
+ *
+ * Set depth to 0, offset to parent, then call this function repeatedly
+ * to get direct subnodes of a parent node.
+ *
+ * @fdt: FDT blob
+ * @offset: Set this to offset of parent for the first call. For
+ * subsquent calls, pass in the value returns from the last
+ * call.
+ * @depth: Used internally to monitor depth - set this to 0 for the
+ * first call.
+ * @return offset of next subnode, or -FDT_ERR_NOTFOUND if there are no more
+ * subnodes
+ */
+int fdt_next_subnode(const void *fdt, int offset, int *depth);
+
/**********************************************************************/
/* General functions */
/**********************************************************************/
diff --git a/tests/Makefile.tests b/tests/Makefile.tests
index d59bff8..dafb618 100644
--- a/tests/Makefile.tests
+++ b/tests/Makefile.tests
@@ -20,7 +20,8 @@ LIB_TESTS_L = get_mem_rsv \
dtb_reverse dtbs_equal_unordered \
add_subnode_with_nops path_offset_aliases \
utilfdt_test \
- integer-expressions
+ integer-expressions \
+ subnode_iterate
LIB_TESTS = $(LIB_TESTS_L:%=$(TESTS_PREFIX)%)
LIBTREE_TESTS_L = truncated_property
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index b56b626..b013761 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -241,6 +241,9 @@ libfdt_tests () {
tree1_tests_rw noppy.$basetree
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
run_test truncated_property
diff --git a/tests/subnode_iterate.c b/tests/subnode_iterate.c
new file mode 100644
index 0000000..9a36bb6
--- /dev/null
+++ b/tests/subnode_iterate.c
@@ -0,0 +1,97 @@
+/*
+ * 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 depth;
+ 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 (depth = 0, offset = fdt_next_subnode(fdt, parent_offset, &depth);
+ offset >= 0;
+ offset = fdt_next_subnode(fdt, offset, &depth)) {
+ 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 depth;
+ int offset;
+ int count = 0;
+
+ for (depth = 0, offset = fdt_next_subnode(fdt, 0, &depth);
+ offset >= 0;
+ offset = fdt_next_subnode(fdt, offset, &depth)) {
+ 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();
+}
diff --git a/tests/subnode_iterate.dts b/tests/subnode_iterate.dts
new file mode 100644
index 0000000..14a0d3a
--- /dev/null
+++ b/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 at 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 at 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>;
+ };
+};
+
--
1.8.2.1
More information about the devicetree-discuss
mailing list