From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Glass Subject: [PATCH v2 3/6] Add fdtget utility to read property values from device tree Date: Wed, 7 Sep 2011 12:54:17 -0700 Message-ID: <1315425260-2711-4-git-send-email-sjg@chromium.org> References: <1315425260-2711-1-git-send-email-sjg@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1315425260-2711-1-git-send-email-sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org To: Devicetree Discuss List-Id: devicetree@vger.kernel.org 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: -t [][] Type of data -h Print this help One character (s=string, i=int, u=unsigned, b=byte) Optional format character (x=hex) Signed-off-by: Simon Glass --- 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 + */ + +#include +#include +#include +#include +#include + +#include + +#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
[ ]...\n" + "Options:\n" + "\t-t [][]\tType of data\n" + "\t-h\t\tPrint this help\n\n" + "\t\t\tOne character (s=string, i=int, u=unsigned, b=byte)\n" + "\t\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