This simply utility makes it easy for scripts to read values from the device
tree. It is written in C and uses the same libfdt as the rest of the dtc
package.
What is it for:
- Reading fdt values from scripts
- Extracting fdt information within build systems
- Looking at particular values without having to dump the entire tree
To use it, specify the fdt binary file on command line followed by a list of
node, property pairs. The utility then looks up each node, finds the property
and displays the value.
Each value is printed on a new line.
fdtget tries to guess the type of each property based on its contents. This
is not always reliable, so you can use the -t option to force fdtget to decode
the value as a string, or byte, etc.
To read from stdin, use - as the file.
Usage:
fdtget <options> <dt file> [<node> <property>]...
Options:
-t [<type>][<format>] Type of data
-h Print this help
<type> One character (s=string, i=int, u=unsigned, b=byte)
<format> Optional format character (x=hex)
Signed-off-by: Simon Glass <[email protected]>
---
Changes in v2:
- Separate arguments for node and property
- Merge two related commits into this one
- Use structure for storing display options
- Remove use of getopt_long()
.gitignore | 1 +
Makefile | 4 +
Makefile.fdtget | 12 +++
fdtget.c | 200 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 217 insertions(+), 0 deletions(-)
create mode 100644 Makefile.fdtget
create mode 100644 fdtget.c
diff --git a/.gitignore b/.gitignore
index ae7a46a..9f27f34 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,3 +10,4 @@ lex.yy.c
/ftdump
/convert-dtsv0
/version_gen.h
+/fdtget
diff --git a/Makefile b/Makefile
index 0baada5..3d460d7 100644
--- a/Makefile
+++ b/Makefile
@@ -106,10 +106,12 @@ endef
include Makefile.convert-dtsv0
include Makefile.dtc
include Makefile.ftdump
+include Makefile.fdtget
BIN += convert-dtsv0
BIN += dtc
BIN += ftdump
+BIN += fdtget
SCRIPTS = dtdiff
@@ -120,6 +122,7 @@ ifneq ($(DEPTARGETS),)
-include $(DTC_OBJS:%.o=%.d)
-include $(CONVERT_OBJS:%.o=%.d)
-include $(FTDUMP_OBJS:%.o=%.d)
+-include $(FDTGET_OBJS:%.o=%.d)
endif
@@ -180,6 +183,7 @@ convert-dtsv0: $(CONVERT_OBJS)
ftdump: $(FTDUMP_OBJS) $(LIBFDT_archive)
+fdtget: $(FDTGET_OBJS) $(LIBFDT_archive)
#
# Testsuite rules
diff --git a/Makefile.fdtget b/Makefile.fdtget
new file mode 100644
index 0000000..c1ab041
--- /dev/null
+++ b/Makefile.fdtget
@@ -0,0 +1,12 @@
+#
+# This is not a complete Makefile.
+# Instead, it is designed to be easily embeddable
+# into other systems of Makefiles.
+#
+
+FDTGET_SRCS = \
+ fdtget.c \
+ util.c \
+ utilfdt.c
+
+FDTGET_OBJS = $(FDTGET_SRCS:%.c=%.o)
diff --git a/fdtget.c b/fdtget.c
new file mode 100644
index 0000000..4a94e99
--- /dev/null
+++ b/fdtget.c
@@ -0,0 +1,200 @@
+/*
+ * Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+ * Distributed under the terms of the GNU General Public License v2
+ *
+ * is_printable_string from ftdump.c
+ * Contributed by Pantelis Antoniou <pantelis.antoniou AT gmail.com>
+ */
+
+#include <ctype.h>
+#include <getopt.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <libfdt.h>
+
+#include "util.h"
+#include "utilfdt.h"
+
+/* Holds information which controls our output and options */
+struct display_info {
+ int type; /* data type (s/i/u/b or 0 for default) */
+ int format; /* data format (x or 0 for default) */
+};
+
+static void report_error(const char *where, int err)
+{
+ fprintf(stderr, "Error at '%s': %s\n", where, fdt_strerror(err));
+}
+
+/**
+ * Displays data of a given length according to selected options
+ *
+ * If a specific data type is provided in disp, then this is used. Otherwise
+ * we try to guess the data type / size from the contents.
+ *
+ * @param disp Display information / options
+ * @param data Data to display
+ * @param len Maximum length of buffer
+ */
+static void show_data(struct display_info *disp, const char *data, int len)
+{
+ int i, size;
+ const char *p = data, *s;
+ int value;
+ int is_string;
+
+ /* no data, don't print */
+ if (len == 0)
+ return;
+
+ is_string = (disp->type) == 's' ||
+ (!disp->type && util_is_printable_string(data, len));
+ if (is_string) {
+ for (s = data; s - data < len; s += strlen(s) + 1) {
+ if (s != data)
+ printf(" ");
+ printf("%s", (const char *)s);
+ }
+ return;
+ }
+ if (disp->type == 'i' || disp->type == 'u')
+ size = 4;
+ else if (disp->type == 'b')
+ size = 1;
+ else
+ size = (len % 4) == 0 ? 4 : 1;
+ for (i = 0; i < len; i += size, p += size) {
+ if (i)
+ printf(" ");
+ value = size == 4 ? fdt32_to_cpu(*(const uint32_t *)p) :
+ *(const unsigned char *)p;
+ printf(disp->format == 'x' ? "%x" : "%d", value);
+ }
+}
+
+/**
+ * Show the data for a given node (and perhaps property) according to the
+ * display option provided.
+ *
+ * @param blob FDT blob
+ * @param disp Display information / options
+ * @param node Node to display
+ * @param property Name of property to display, or NULL if none
+ * @return 0 if ok, -ve on error
+ */
+static int show_data_for_item(const void *blob, struct display_info *disp,
+ int node, const char *property)
+{
+ const void *value = NULL;
+ int len, err = 0;
+
+ value = fdt_getprop(blob, node, property, &len);
+ if (value) {
+ show_data(disp, value, len);
+ printf("\n");
+ } else {
+ report_error(property, len);
+ err = -1;
+ }
+ return err;
+}
+
+/**
+ * Run the main fdtget operation, given a filename and valid arguments
+ *
+ * @param disp Display information / options
+ * @param filename Filename of blob file
+ * @param arg List of arguments to process
+ * @param arg_count Number of arguments
+ * @param return 0 if ok, -ve on error
+ */
+static int do_fdtget(struct display_info *disp, const char *filename,
+ char **arg, int arg_count)
+{
+ char *blob;
+ int i, node;
+
+ blob = util_read_fdt(filename);
+ if (!blob)
+ return -1;
+
+ for (i = 0; i + 2 <= arg_count; i += 2) {
+ node = fdt_path_offset(blob, arg[0]);
+ if (node < 0) {
+ report_error(arg[0], node);
+ return -1;
+ }
+
+ if (show_data_for_item(blob, disp, node, arg[1]))
+ return -1;
+ }
+ return 0;
+}
+
+static const char *usage_msg =
+ "fdtget - read values from device tree\n"
+ "\n"
+ "Each value is printed on a new line.\n\n"
+ "Usage:\n"
+ " fdtget <options> <dt file> [<node> <property>]...\n"
+ "Options:\n"
+ "\t-t [<type>][<format>]\tType of data\n"
+ "\t-h\t\tPrint this help\n\n"
+ "\t<type>\t\tOne character (s=string, i=int, u=unsigned, b=byte)\n"
+ "\t<format>\tOptional format character (x=hex)\n";
+
+static void usage(const char *msg)
+{
+ if (msg)
+ fprintf(stderr, "Error: %s\n\n", msg);
+
+ fprintf(stderr, "%s", usage_msg);
+ exit(2);
+}
+
+int main(int argc, char *argv[])
+{
+ char *filename = NULL;
+ struct display_info disp;
+
+ memset(&disp, '\0', sizeof(disp));
+ for (;;) {
+ int c = getopt(argc, argv, "ht:");
+ if (c == -1)
+ break;
+
+ switch (c) {
+ case 'h':
+ case '?':
+ usage("");
+
+ case 't':
+ if (utilfdt_decode_type(optarg, &disp.type,
+ &disp.format))
+ usage("Invalid type string");
+ break;
+ }
+ }
+
+ if (optind < argc)
+ filename = argv[optind++];
+ if (!filename)
+ usage("Missing filename");
+
+ argv += optind;
+ argc -= optind;
+
+ /* Allow no arguments, and silently succeed */
+ if (!argc)
+ return 0;
+
+ /* Check for node, property arguments */
+ if (argc % 2)
+ usage("Must have an even number of arguments");
+
+ if (do_fdtget(&disp, filename, argv, argc))
+ return 1;
+ return 0;
+}
--
1.7.3.1
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