fdtget.c revision 238737 
1/*
2 * Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
3 *
4 * Portions from U-Boot cmd_fdt.c (C) Copyright 2007
5 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com
6 * Based on code written by:
7 *   Pantelis Antoniou <pantelis.antoniou@gmail.com> and
8 *   Matthew McClintock <msm@freescale.com>
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License as
12 * published by the Free Software Foundation; either version 2 of
13 * the License, or (at your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18 * GNU General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
23 * MA 02111-1307 USA
24 */
25
26#include <assert.h>
27#include <ctype.h>
28#include <getopt.h>
29#include <stdio.h>
30#include <stdlib.h>
31#include <string.h>
32
33#include <libfdt.h>
34
35#include "util.h"
36
37enum display_mode {
38	MODE_SHOW_VALUE,	/* show values for node properties */
39	MODE_LIST_PROPS,	/* list the properties for a node */
40	MODE_LIST_SUBNODES,	/* list the subnodes of a node */
41};
42
43/* Holds information which controls our output and options */
44struct display_info {
45	int type;		/* data type (s/i/u/x or 0 for default) */
46	int size;		/* data size (1/2/4) */
47	enum display_mode mode;	/* display mode that we are using */
48	const char *default_val; /* default value if node/property not found */
49};
50
51static void report_error(const char *where, int err)
52{
53	fprintf(stderr, "Error at '%s': %s\n", where, fdt_strerror(err));
54}
55
56/**
57 * Displays data of a given length according to selected options
58 *
59 * If a specific data type is provided in disp, then this is used. Otherwise
60 * we try to guess the data type / size from the contents.
61 *
62 * @param disp		Display information / options
63 * @param data		Data to display
64 * @param len		Maximum length of buffer
65 * @return 0 if ok, -1 if data does not match format
66 */
67static int show_data(struct display_info *disp, const char *data, int len)
68{
69	int i, size;
70	const uint8_t *p = (const uint8_t *)data;
71	const char *s;
72	int value;
73	int is_string;
74	char fmt[3];
75
76	/* no data, don't print */
77	if (len == 0)
78		return 0;
79
80	is_string = (disp->type) == 's' ||
81		(!disp->type && util_is_printable_string(data, len));
82	if (is_string) {
83		if (data[len - 1] != '\0') {
84			fprintf(stderr, "Unterminated string\n");
85			return -1;
86		}
87		for (s = data; s - data < len; s += strlen(s) + 1) {
88			if (s != data)
89				printf(" ");
90			printf("%s", (const char *)s);
91		}
92		return 0;
93	}
94	size = disp->size;
95	if (size == -1) {
96		size = (len % 4) == 0 ? 4 : 1;
97	} else if (len % size) {
98		fprintf(stderr, "Property length must be a multiple of "
99				"selected data size\n");
100		return -1;
101	}
102	fmt[0] = '%';
103	fmt[1] = disp->type ? disp->type : 'd';
104	fmt[2] = '\0';
105	for (i = 0; i < len; i += size, p += size) {
106		if (i)
107			printf(" ");
108		value = size == 4 ? fdt32_to_cpu(*(const uint32_t *)p) :
109			size == 2 ? (*p << 8) | p[1] : *p;
110		printf(fmt, value);
111	}
112	return 0;
113}
114
115/**
116 * List all properties in a node, one per line.
117 *
118 * @param blob		FDT blob
119 * @param node		Node to display
120 * @return 0 if ok, or FDT_ERR... if not.
121 */
122static int list_properties(const void *blob, int node)
123{
124	const struct fdt_property *data;
125	const char *name;
126	int prop;
127
128	prop = fdt_first_property_offset(blob, node);
129	do {
130		/* Stop silently when there are no more properties */
131		if (prop < 0)
132			return prop == -FDT_ERR_NOTFOUND ? 0 : prop;
133		data = fdt_get_property_by_offset(blob, prop, NULL);
134		name = fdt_string(blob, fdt32_to_cpu(data->nameoff));
135		if (name)
136			puts(name);
137		prop = fdt_next_property_offset(blob, prop);
138	} while (1);
139}
140
141#define MAX_LEVEL	32		/* how deeply nested we will go */
142
143/**
144 * List all subnodes in a node, one per line
145 *
146 * @param blob		FDT blob
147 * @param node		Node to display
148 * @return 0 if ok, or FDT_ERR... if not.
149 */
150static int list_subnodes(const void *blob, int node)
151{
152	int nextoffset;		/* next node offset from libfdt */
153	uint32_t tag;		/* current tag */
154	int level = 0;		/* keep track of nesting level */
155	const char *pathp;
156	int depth = 1;		/* the assumed depth of this node */
157
158	while (level >= 0) {
159		tag = fdt_next_tag(blob, node, &nextoffset);
160		switch (tag) {
161		case FDT_BEGIN_NODE:
162			pathp = fdt_get_name(blob, node, NULL);
163			if (level <= depth) {
164				if (pathp == NULL)
165					pathp = "/* NULL pointer error */";
166				if (*pathp == '\0')
167					pathp = "/";	/* root is nameless */
168				if (level == 1)
169					puts(pathp);
170			}
171			level++;
172			if (level >= MAX_LEVEL) {
173				printf("Nested too deep, aborting.\n");
174				return 1;
175			}
176			break;
177		case FDT_END_NODE:
178			level--;
179			if (level == 0)
180				level = -1;		/* exit the loop */
181			break;
182		case FDT_END:
183			return 1;
184		case FDT_PROP:
185			break;
186		default:
187			if (level <= depth)
188				printf("Unknown tag 0x%08X\n", tag);
189			return 1;
190		}
191		node = nextoffset;
192	}
193	return 0;
194}
195
196/**
197 * Show the data for a given node (and perhaps property) according to the
198 * display option provided.
199 *
200 * @param blob		FDT blob
201 * @param disp		Display information / options
202 * @param node		Node to display
203 * @param property	Name of property to display, or NULL if none
204 * @return 0 if ok, -ve on error
205 */
206static int show_data_for_item(const void *blob, struct display_info *disp,
207		int node, const char *property)
208{
209	const void *value = NULL;
210	int len, err = 0;
211
212	switch (disp->mode) {
213	case MODE_LIST_PROPS:
214		err = list_properties(blob, node);
215		break;
216
217	case MODE_LIST_SUBNODES:
218		err = list_subnodes(blob, node);
219		break;
220
221	default:
222		assert(property);
223		value = fdt_getprop(blob, node, property, &len);
224		if (value) {
225			if (show_data(disp, value, len))
226				err = -1;
227			else
228				printf("\n");
229		} else if (disp->default_val) {
230			puts(disp->default_val);
231		} else {
232			report_error(property, len);
233			err = -1;
234		}
235		break;
236	}
237
238	return err;
239}
240
241/**
242 * Run the main fdtget operation, given a filename and valid arguments
243 *
244 * @param disp		Display information / options
245 * @param filename	Filename of blob file
246 * @param arg		List of arguments to process
247 * @param arg_count	Number of arguments
248 * @param return 0 if ok, -ve on error
249 */
250static int do_fdtget(struct display_info *disp, const char *filename,
251		     char **arg, int arg_count, int args_per_step)
252{
253	char *blob;
254	const char *prop;
255	int i, node;
256
257	blob = utilfdt_read(filename);
258	if (!blob)
259		return -1;
260
261	for (i = 0; i + args_per_step <= arg_count; i += args_per_step) {
262		node = fdt_path_offset(blob, arg[i]);
263		if (node < 0) {
264			if (disp->default_val) {
265				puts(disp->default_val);
266				continue;
267			} else {
268				report_error(arg[i], node);
269				return -1;
270			}
271		}
272		prop = args_per_step == 1 ? NULL : arg[i + 1];
273
274		if (show_data_for_item(blob, disp, node, prop))
275			return -1;
276	}
277	return 0;
278}
279
280static const char *usage_msg =
281	"fdtget - read values from device tree\n"
282	"\n"
283	"Each value is printed on a new line.\n\n"
284	"Usage:\n"
285	"	fdtget <options> <dt file> [<node> <property>]...\n"
286	"	fdtget -p <options> <dt file> [<node> ]...\n"
287	"Options:\n"
288	"\t-t <type>\tType of data\n"
289	"\t-p\t\tList properties for each node\n"
290	"\t-l\t\tList subnodes for each node\n"
291	"\t-d\t\tDefault value to display when the property is "
292			"missing\n"
293	"\t-h\t\tPrint this help\n\n"
294	USAGE_TYPE_MSG;
295
296static void usage(const char *msg)
297{
298	if (msg)
299		fprintf(stderr, "Error: %s\n\n", msg);
300
301	fprintf(stderr, "%s", usage_msg);
302	exit(2);
303}
304
305int main(int argc, char *argv[])
306{
307	char *filename = NULL;
308	struct display_info disp;
309	int args_per_step = 2;
310
311	/* set defaults */
312	memset(&disp, '\0', sizeof(disp));
313	disp.size = -1;
314	disp.mode = MODE_SHOW_VALUE;
315	for (;;) {
316		int c = getopt(argc, argv, "d:hlpt:");
317		if (c == -1)
318			break;
319
320		switch (c) {
321		case 'h':
322		case '?':
323			usage(NULL);
324
325		case 't':
326			if (utilfdt_decode_type(optarg, &disp.type,
327					&disp.size))
328				usage("Invalid type string");
329			break;
330
331		case 'p':
332			disp.mode = MODE_LIST_PROPS;
333			args_per_step = 1;
334			break;
335
336		case 'l':
337			disp.mode = MODE_LIST_SUBNODES;
338			args_per_step = 1;
339			break;
340
341		case 'd':
342			disp.default_val = optarg;
343			break;
344		}
345	}
346
347	if (optind < argc)
348		filename = argv[optind++];
349	if (!filename)
350		usage("Missing filename");
351
352	argv += optind;
353	argc -= optind;
354
355	/* Allow no arguments, and silently succeed */
356	if (!argc)
357		return 0;
358
359	/* Check for node, property arguments */
360	if (args_per_step == 2 && (argc % 2))
361		usage("Must have an even number of arguments");
362
363	if (do_fdtget(&disp, filename, argv, argc, args_per_step))
364		return 1;
365	return 0;
366}
367