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

[Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>]

On Tue, Jul 05, 2011 at 12:02:50PM -0700, Simon Glass wrote:
> This simply utility makes it easy for scripts to read values from the device
> tree.
> 
> Signed-off-by: Simon Glass <sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>

Looks okay to me.

g.

> ---
>  .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
>