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* Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
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* Portions from U-Boot cmd_fdt.c (C) Copyright 2007
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* Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com
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* Based on code written by:
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* Pantelis Antoniou <pantelis.antoniou@gmail.com> and
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* Matthew McClintock <msm@freescale.com>
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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MODE_SHOW_VALUE, /* show values for node properties */
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MODE_LIST_PROPS, /* list the properties for a node */
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MODE_LIST_SUBNODES, /* list the subnodes of a node */
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/* Holds information which controls our output and options */
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int type; /* data type (s/i/u/x or 0 for default) */
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int size; /* data size (1/2/4) */
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enum display_mode mode; /* display mode that we are using */
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const char *default_val; /* default value if node/property not found */
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static void report_error(const char *where, int err)
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fprintf(stderr, "Error at '%s': %s\n", where, fdt_strerror(err));
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* Displays data of a given length according to selected options
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* If a specific data type is provided in disp, then this is used. Otherwise
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* we try to guess the data type / size from the contents.
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* @param disp Display information / options
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* @param data Data to display
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* @param len Maximum length of buffer
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* @return 0 if ok, -1 if data does not match format
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static int show_data(struct display_info *disp, const char *data, int len)
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const uint8_t *p = (const uint8_t *)data;
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/* no data, don't print */
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is_string = (disp->type) == 's' ||
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(!disp->type && util_is_printable_string(data, len));
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if (data[len - 1] != '\0') {
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fprintf(stderr, "Unterminated string\n");
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for (s = data; s - data < len; s += strlen(s) + 1) {
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printf("%s", (const char *)s);
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size = (len % 4) == 0 ? 4 : 1;
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} else if (len % size) {
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fprintf(stderr, "Property length must be a multiple of "
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"selected data size\n");
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fmt[1] = disp->type ? disp->type : 'd';
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for (i = 0; i < len; i += size, p += size) {
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value = size == 4 ? fdt32_to_cpu(*(const fdt32_t *)p) :
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size == 2 ? (*p << 8) | p[1] : *p;
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* List all properties in a node, one per line.
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* @param blob FDT blob
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* @param node Node to display
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* @return 0 if ok, or FDT_ERR... if not.
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static int list_properties(const void *blob, int node)
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const struct fdt_property *data;
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prop = fdt_first_property_offset(blob, node);
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/* Stop silently when there are no more properties */
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return prop == -FDT_ERR_NOTFOUND ? 0 : prop;
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data = fdt_get_property_by_offset(blob, prop, NULL);
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name = fdt_string(blob, fdt32_to_cpu(data->nameoff));
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prop = fdt_next_property_offset(blob, prop);
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#define MAX_LEVEL 32 /* how deeply nested we will go */
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* List all subnodes in a node, one per line
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* @param blob FDT blob
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* @param node Node to display
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* @return 0 if ok, or FDT_ERR... if not.
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static int list_subnodes(const void *blob, int node)
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int nextoffset; /* next node offset from libfdt */
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uint32_t tag; /* current tag */
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int level = 0; /* keep track of nesting level */
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int depth = 1; /* the assumed depth of this node */
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tag = fdt_next_tag(blob, node, &nextoffset);
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pathp = fdt_get_name(blob, node, NULL);
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if (level <= depth) {
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pathp = "/* NULL pointer error */";
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pathp = "/"; /* root is nameless */
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if (level >= MAX_LEVEL) {
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printf("Nested too deep, aborting.\n");
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level = -1; /* exit the loop */
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printf("Unknown tag 0x%08X\n", tag);
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* Show the data for a given node (and perhaps property) according to the
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* display option provided.
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* @param blob FDT blob
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* @param disp Display information / options
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* @param node Node to display
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* @param property Name of property to display, or NULL if none
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* @return 0 if ok, -ve on error
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static int show_data_for_item(const void *blob, struct display_info *disp,
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int node, const char *property)
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const void *value = NULL;
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switch (disp->mode) {
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case MODE_LIST_PROPS:
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err = list_properties(blob, node);
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case MODE_LIST_SUBNODES:
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err = list_subnodes(blob, node);
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value = fdt_getprop(blob, node, property, &len);
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if (show_data(disp, value, len))
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} else if (disp->default_val) {
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puts(disp->default_val);
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report_error(property, len);
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* Run the main fdtget operation, given a filename and valid arguments
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* @param disp Display information / options
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* @param filename Filename of blob file
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* @param arg List of arguments to process
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* @param arg_count Number of arguments
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* @return 0 if ok, -ve on error
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static int do_fdtget(struct display_info *disp, const char *filename,
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char **arg, int arg_count, int args_per_step)
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blob = utilfdt_read(filename);
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for (i = 0; i + args_per_step <= arg_count; i += args_per_step) {
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node = fdt_path_offset(blob, arg[i]);
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if (disp->default_val) {
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puts(disp->default_val);
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report_error(arg[i], node);
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prop = args_per_step == 1 ? NULL : arg[i + 1];
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if (show_data_for_item(blob, disp, node, prop)) {
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/* Usage related data. */
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static const char usage_synopsis[] =
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"read values from device tree\n"
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" fdtget <options> <dt file> [<node> <property>]...\n"
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" fdtget -p <options> <dt file> [<node> ]...\n"
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"Each value is printed on a new line.\n"
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static const char usage_short_opts[] = "t:pld:" USAGE_COMMON_SHORT_OPTS;
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static struct option const usage_long_opts[] = {
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{"type", a_argument, NULL, 't'},
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{"properties", no_argument, NULL, 'p'},
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{"list", no_argument, NULL, 'l'},
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{"default", a_argument, NULL, 'd'},
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USAGE_COMMON_LONG_OPTS,
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static const char * const usage_opts_help[] = {
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"List properties for each node",
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"List subnodes for each node",
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"Default value to display when the property is missing",
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USAGE_COMMON_OPTS_HELP
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int main(int argc, char *argv[])
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char *filename = NULL;
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struct display_info disp;
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int args_per_step = 2;
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memset(&disp, '\0', sizeof(disp));
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disp.mode = MODE_SHOW_VALUE;
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while ((opt = util_getopt_long()) != EOF) {
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case_USAGE_COMMON_FLAGS
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if (utilfdt_decode_type(optarg, &disp.type,
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usage("invalid type string");
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disp.mode = MODE_LIST_PROPS;
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disp.mode = MODE_LIST_SUBNODES;
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disp.default_val = optarg;
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filename = argv[optind++];
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usage("missing filename");
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/* Allow no arguments, and silently succeed */
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/* Check for node, property arguments */
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if (args_per_step == 2 && (argc % 2))
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usage("must have an even number of arguments");
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if (do_fdtget(&disp, filename, argv, argc, args_per_step))