[PATCH 2/9] Add dtget utility to read property values from device tree

[Simon Glass]

This simply utility makes it easy for scripts to read values from the device
tree.

Signed-off-by: Simon Glass <sjg at chromium.org>
---
 .gitignore     |    1 +
 Makefile       |    7 ++
 Makefile.dtget |   13 ++++
 dtget.c        |  207 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 228 insertions(+), 0 deletions(-)
 create mode 100644 Makefile.dtget
 create mode 100644 dtget.c

diff --git a/.gitignore b/.gitignore
index ae7a46a..cde4fa5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,3 +10,4 @@ lex.yy.c
 /ftdump
 /convert-dtsv0
 /version_gen.h
+/dtget
diff --git a/Makefile b/Makefile
index 22f79a0..3401a65 100644
--- a/Makefile
+++ b/Makefile
@@ -106,10 +106,12 @@ endef
 include Makefile.convert-dtsv0
 include Makefile.dtc
 include Makefile.ftdump
+include Makefile.dtget
 
 BIN += convert-dtsv0
 BIN += dtc
 BIN += ftdump
+BIN += dtget
 
 SCRIPTS = dtdiff
 
@@ -120,6 +122,7 @@ ifneq ($(DEPTARGETS),)
 -include $(DTC_OBJS:%.o=%.d)
 -include $(CONVERT_OBJS:%.o=%.d)
 -include $(FTDUMP_OBJS:%.o=%.d)
+-include $(DTGET_OBJS:%.o=%.d)
 endif
 
 
@@ -180,6 +183,10 @@ convert-dtsv0: $(CONVERT_OBJS)
 
 ftdump:	$(FTDUMP_OBJS)
 
+dtget:	$(DTGET_OBJS) $(LIBFDT_archive)
+	$(VECHO) LD $@
+	$(LINK.c) -o $@ $^
+
 
 #
 # Testsuite rules
diff --git a/Makefile.dtget b/Makefile.dtget
new file mode 100644
index 0000000..edda499
--- /dev/null
+++ b/Makefile.dtget
@@ -0,0 +1,13 @@
+#
+# This is not a complete Makefile.
+# Instead, it is designed to be easily embeddable
+# into other systems of Makefiles.
+#
+
+DTGET_SRCS = \
+	dtget.c \
+	util.c
+
+DTGET_GEN_SRCS =
+
+DTGET_OBJS = $(DTGET_SRCS:%.c=%.o) $(DTGET_GEN_SRCS:%.c=%.o)
diff --git a/dtget.c b/dtget.c
new file mode 100644
index 0000000..0ee577c
--- /dev/null
+++ b/dtget.c
@@ -0,0 +1,207 @@
+/*
+ * 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 <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <getopt.h>
+#include <ctype.h>
+
+#include <libfdt.h>
+
+#include "util.h"
+
+#define FTDUMP_BUF_SIZE	65536
+
+static void report_error(const char *where, int err)
+{
+	fprintf(stderr, "Error at '%s': %s\n", where, fdt_strerror(err));
+}
+
+static void show_data(const char *format, int type, 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 = type == 's' ||
+		(!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(format ? format : "%s", (const char *)s);
+		}
+		return;
+	}
+	if (type == 'i')
+		size = 4;
+	else if (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(format ? format : "%d", value);
+	}
+}
+
+static int show_data_for_key(const void *blob, const char *format, int type,
+			     char *key)
+{
+	char *ptr, *prop;
+	int node, guess_node = 0;
+	const void *value;
+	int len;
+
+	/* First extract the property from the end */
+	ptr = strrchr(key, '/');
+	if (!ptr) {
+		fprintf(stderr, "No node found in key '%s'\n", key);
+		return 5;
+	}
+
+	if (ptr == key) {
+		guess_node = fdt_path_offset(blob, key);
+		node = fdt_path_offset(blob, "/");
+	} else {
+		*ptr = '\0';
+		node = fdt_path_offset(blob, key);
+		*ptr = '/';
+	}
+	if (node < 0) {
+		report_error(key, node);
+		return 7;
+	}
+	prop = ptr + 1;
+	value = fdt_getprop(blob, node, prop, &len);
+	if (!value) {
+		report_error(prop, len);
+		if (guess_node)
+			fprintf(stderr, "(Node %s exists but you didn't "
+				"specify a property to print)\n", key);
+		return 8;
+	}
+	show_data(format, type, value, len);
+	printf("\n");
+	return 0;
+}
+
+static int do_dtget(const char *filename, const char *format, int type,
+		    char **key, int key_count)
+{
+	FILE *fp;
+	char *buf;
+	size_t size;
+	int i, ret;
+
+	if (strcmp(filename, "-") == 0) {
+		fp = stdin;
+	} else {
+		fp = fopen(filename, "rb");
+		if (fp == NULL) {
+			fprintf(stderr, "unable to open %s\n", filename);
+			return 10;
+		}
+	}
+
+	buf = malloc(FTDUMP_BUF_SIZE);
+	if (!buf) {
+		fprintf(stderr, "Couldn't allocate %d byte buffer\n",
+			FTDUMP_BUF_SIZE);
+		return 10;
+	}
+
+	size = fread(buf, 1, FTDUMP_BUF_SIZE, fp);
+	if (!feof(fp)) {
+		fprintf(stderr, "file too large (maximum is %d bytes)\n",
+			FTDUMP_BUF_SIZE);
+		return 10;
+	}
+	if (ferror(fp)) {
+		fprintf(stderr, "file read error\n");
+		return 10;
+	}
+	for (i = 0; i < key_count; i++) {
+		ret = show_data_for_key(buf, format, type, key[i]);
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+static void usage(const char *msg)
+{
+	if (msg)
+		fprintf(stderr, "Error: %s\n\n", msg);
+	fprintf(stderr, "dtget - read values from device tree\n\n");
+	fprintf(stderr, "Usage: dtget <options> <dt file> <key>...\n");
+	fprintf(stderr, "Options:\n");
+	fprintf(stderr, "\t-f, --format <fmt>\tPrintf format string to use "
+		"for value\n");
+	fprintf(stderr, "\t-t, --type <typechar>\tForce type to be string "
+		"(s), int(i) or byte(b)\n");
+	fprintf(stderr, "\t-h, --help\t\tPrint this help\n\n");
+	fprintf(stderr, "\t<key> is <node>/<property>, for example "
+		"/lcd/width for the width\n");
+	fprintf(stderr, "\tproperty in the LCD node\n");
+	exit(2);
+}
+
+int main(int argc, char *argv[])
+{
+	int c;
+	int ret;
+	char *format = NULL;
+	int type = 0;
+	char *filename = NULL;
+	static struct option long_options[] = {
+		{"format", 1, 0, 'f'},
+		{"help", 1, 0, 'h'},
+		{"type", 1, 0, 't'},
+		{0, 0, 0, 0}
+	};
+
+	for (;;) {
+		c = getopt_long(argc, argv, "f:ht:", long_options, NULL);
+		if (c == -1)
+			break;
+
+		switch (c) {
+		case 'h':
+		case '?':
+			usage("");
+
+		case 'f':
+			format = optarg;
+			break;
+
+		case 't':
+			type = *optarg;
+			break;
+		}
+	}
+
+	if (optind < argc)
+		filename = argv[optind++];
+	if (!filename)
+		usage("Missing filename");
+	if (optind == argc)
+		usage("Missing key(s)");
+
+	ret = do_dtget(filename, format, type, argv + optind, argc - optind);
+	return ret;
+}
-- 
1.7.3.1