1 /*
2 * Copyright © 2018 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 * SOFTWARE.
22 *
23 * DPCD register read/write tool
24 * This tool wraps around DRM_DP_AUX_DEV module to provide DPCD register read
25 * and write, so CONFIG_DRM_DP_AUX_DEV needs to be set.
26 */
27
28 #include <stdio.h>
29 #include <errno.h>
30 #include <string.h>
31 #include <stdlib.h>
32 #include <fcntl.h>
33 #include <getopt.h>
34 #include <stdint.h>
35 #include <unistd.h>
36 #include <limits.h>
37 #include <stdbool.h>
38
39 #define MAX_DP_OFFSET 0xfffff
40 #define DRM_AUX_MINORS 256
41
42 const char aux_dev[] = "/dev/drm_dp_aux";
43
44 struct dpcd_block {
45 /* DPCD dump start address. */
46 uint32_t offset;
47 /* DPCD number of bytes to read. If unset, defaults to 1. */
48 size_t count;
49 };
50
51 struct dpcd_data {
52 int devid;
53 int file_op;
54 struct dpcd_block rw;
55 enum command {
56 DUMP,
57 READ,
58 WRITE,
59 } cmd;
60 uint8_t val;
61 };
62
63 static const struct dpcd_block dump_list[] = {
64 /* DP_DPCD_REV */
65 { .offset = 0, .count = 15 },
66 /* DP_PSR_SUPPORT to DP_PSR_CAPS*/
67 { .offset = 0x70, .count = 2 },
68 /* DP_DOWNSTREAM_PORT_0 */
69 { .offset = 0x80, .count = 16 },
70 /* DP_LINK_BW_SET to DP_EDP_CONFIGURATION_SET */
71 { .offset = 0x100, .count = 11 },
72 /* DP_SINK_COUNT to DP_ADJUST_REQUEST_LANE2_3 */
73 { .offset = 0x200, .count = 8 },
74 /* DP_SET_POWER */
75 { .offset = 0x600 },
76 /* DP_EDP_DPCD_REV */
77 { .offset = 0x700 },
78 /* DP_EDP_GENERAL_CAP_1 to DP_EDP_GENERAL_CAP_3 */
79 { .offset = 0x701, .count = 4 },
80 /* DP_EDP_DISPLAY_CONTROL_REGISTER to DP_EDP_BACKLIGHT_FREQ_CAP_MAX_LSB */
81 { .offset = 0x720, .count = 16},
82 /* DP_EDP_DBC_MINIMUM_BRIGHTNESS_SET to DP_EDP_DBC_MAXIMUM_BRIGHTNESS_SET */
83 { .offset = 0x732, .count = 2 },
84 /* DP_PSR_STATUS to DP_PSR_STATUS */
85 { .offset = 0x2008, .count = 1 },
86 };
87
print_usage(void)88 static void print_usage(void)
89 {
90 printf("Usage: dpcd_reg [OPTION ...] COMMAND\n\n");
91 printf("COMMAND is one of:\n");
92 printf(" read: Read [count] bytes dpcd reg at an offset\n");
93 printf(" write: Write a dpcd reg at an offset\n\n");
94 printf("Options for the above COMMANDS are\n");
95 printf(" --device=DEVID Aux device id, as listed in /dev/drm_dp_aux_dev[n]. Defaults to 0. Upper limit - 256\n");
96 printf(" --offset=REG_ADDR DPCD register offset in hex. Defaults to 0x0. Upper limit - 0xfffff\n");
97 printf(" --count=BYTES For reads, specify number of bytes to be read from the offset. Defaults to 1\n");
98 printf(" --value For writes, specify a hex value to be written. Upper limit - 0xff\n\n");
99
100 printf(" --help: print the usage\n");
101 }
102
strtol_err_util(char * endptr,long * val)103 static inline bool strtol_err_util(char *endptr, long *val)
104 {
105 if (*endptr != '\0' || *val < 0 ||
106 (*val == LONG_MAX && errno == ERANGE))
107 return true;
108
109 return false;
110 }
111
parse_opts(struct dpcd_data * dpcd,int argc,char ** argv)112 static int parse_opts(struct dpcd_data *dpcd, int argc, char **argv)
113 {
114 int ret, vflag = 0;
115 long temp;
116 char *endptr;
117
118 struct option longopts[] = {
119 { "count", required_argument, NULL, 'c' },
120 { "device", required_argument, NULL, 'd' },
121 { "help", no_argument, NULL, 'h' },
122 { "offset", required_argument, NULL, 'o' },
123 { "value", required_argument, NULL, 'v' },
124 { 0 }
125 };
126
127 while ((ret = getopt_long(argc, argv, "-:c:d:ho:v:", longopts, NULL)) != -1) {
128 switch (ret) {
129 case 'c':
130 temp = strtol(optarg, &endptr, 10);
131 if (strtol_err_util(endptr, &temp)) {
132 fprintf(stderr,
133 "--count argument is invalid/negative/out-of-range\n");
134 print_usage();
135 return EXIT_FAILURE;
136 }
137 dpcd->rw.count = temp;
138 break;
139 case 'd':
140 temp = strtol(optarg, &endptr, 10);
141 if (strtol_err_util(endptr, &temp) ||
142 temp > DRM_AUX_MINORS) {
143 fprintf(stderr,
144 "--device argument is invalid/negative/out-of-range\n");
145 print_usage();
146 return ERANGE;
147 }
148 dpcd->devid = temp;
149 break;
150 case 'h':
151 printf("DPCD register read and write tool\n\n");
152 printf("This tool requires CONFIG_DRM_DP_AUX_CHARDEV\n"
153 "to be set in the kernel config.\n\n");
154 print_usage();
155 exit(EXIT_SUCCESS);
156 case 'o':
157 temp = strtol(optarg, &endptr, 16);
158 if (strtol_err_util(endptr, &temp) ||
159 temp > MAX_DP_OFFSET) {
160 fprintf(stderr,
161 "--offset argument is invalid/negative/out-of-range\n");
162 print_usage();
163 return ERANGE;
164 }
165 dpcd->rw.offset = temp;
166 break;
167 case 'v':
168 vflag = 'v';
169 temp = strtol(optarg, &endptr, 16);
170 if (strtol_err_util(endptr, &temp) || temp > 0xff) {
171 fprintf(stderr,
172 "--value argument is invalid/negative/out-of-range\n");
173 print_usage();
174 return ERANGE;
175 }
176 dpcd->val = temp;
177 break;
178 /* Command parsing */
179 case 1:
180 if (strcmp(optarg, "read") == 0) {
181 dpcd->cmd = READ;
182 } else if (strcmp(optarg, "write") == 0) {
183 dpcd->cmd = WRITE;
184 dpcd->file_op = O_WRONLY;
185 } else if (strcmp(optarg, "dump") != 0) {
186 fprintf(stderr, "Unrecognized command\n");
187 print_usage();
188 return EXIT_FAILURE;
189 }
190 break;
191 case ':':
192 fprintf(stderr, "Option -%c requires an argument\n",
193 optopt);
194 print_usage();
195 return EXIT_FAILURE;
196 default:
197 fprintf(stderr, "Invalid option\n");
198 print_usage();
199 return EXIT_FAILURE;
200 }
201 }
202
203 if ((dpcd->rw.count + dpcd->rw.offset) > (MAX_DP_OFFSET + 1)) {
204 fprintf(stderr, "Out of bounds. Count + Offset <= 0x100000\n");
205 return ERANGE;
206 }
207
208 if ((dpcd->cmd == WRITE) && (vflag != 'v')) {
209 fprintf(stderr, "Write value is missing\n");
210 print_usage();
211 return EXIT_FAILURE;
212 }
213
214 return EXIT_SUCCESS;
215 }
216
dpcd_read(int fd,uint32_t offset,size_t count)217 static int dpcd_read(int fd, uint32_t offset, size_t count)
218 {
219 int ret = EXIT_SUCCESS, pret, i;
220 uint8_t *buf = calloc(count, sizeof(uint8_t));
221
222 if (!buf) {
223 fprintf(stderr, "Can't allocate read buffer\n");
224 return ENOMEM;
225 }
226
227 pret = pread(fd, buf, count, offset);
228 if (pret < 0) {
229 fprintf(stderr, "Failed to read - %s\n", strerror(errno));
230 ret = errno;
231 goto out;
232 }
233
234 if (pret < count) {
235 fprintf(stderr,
236 "Read %u byte(s), expected %zu bytes, starting at offset %x\n\n", pret, count, offset);
237 ret = EXIT_FAILURE;
238 }
239
240 printf("0x%04x: ", offset);
241 for (i = 0; i < pret; i++)
242 printf(" %02x", *(buf + i));
243 printf("\n");
244
245 out:
246 free(buf);
247 return ret;
248 }
249
dpcd_write(int fd,uint32_t offset,uint8_t val)250 static int dpcd_write(int fd, uint32_t offset, uint8_t val)
251 {
252 int ret = EXIT_SUCCESS, pret;
253
254 pret = pwrite(fd, (const void *)&val, sizeof(uint8_t), offset);
255 if (pret < 0) {
256 fprintf(stderr, "Failed to write - %s\n", strerror(errno));
257 ret = errno;
258 } else if (pret == 0) {
259 fprintf(stderr, "Zero bytes were written\n");
260 ret = EXIT_FAILURE;
261 }
262
263 return ret;
264 }
265
dpcd_dump(int fd)266 static int dpcd_dump(int fd)
267 {
268 size_t count;
269 int ret, i;
270
271 for (i = 0; i < sizeof(dump_list) / sizeof(dump_list[0]); i++) {
272 count = dump_list[i].count ? dump_list[i].count: 1;
273 ret = dpcd_read(fd, dump_list[i].offset, count);
274 if (ret != EXIT_SUCCESS) {
275 fprintf(stderr, "Dump failed while reading %04x\n",
276 dump_list[i].offset);
277 return ret;
278 }
279 }
280 return ret;
281 }
282
main(int argc,char ** argv)283 int main(int argc, char **argv)
284 {
285 char dev_name[20];
286 int ret, fd;
287
288 struct dpcd_data dpcd = {
289 .devid = 0,
290 .file_op = O_RDONLY,
291 .rw.offset = 0x0,
292 .rw.count = 1,
293 .cmd = DUMP,
294 };
295
296 ret = parse_opts(&dpcd, argc, argv);
297 if (ret != EXIT_SUCCESS)
298 return ret;
299
300 snprintf(dev_name, strlen(aux_dev) + 4, "%s%d", aux_dev, dpcd.devid);
301
302 fd = open(dev_name, dpcd.file_op);
303 if (fd < 0) {
304 fprintf(stderr,
305 "Failed to open %s aux device - error: %s\n", dev_name,
306 strerror(errno));
307 return errno;
308 }
309
310 switch (dpcd.cmd) {
311 case READ:
312 ret = dpcd_read(fd, dpcd.rw.offset, dpcd.rw.count);
313 break;
314 case WRITE:
315 ret = dpcd_write(fd, dpcd.rw.offset, dpcd.val);
316 break;
317 case DUMP:
318 default:
319 ret = dpcd_dump(fd);
320 break;
321 }
322
323 close(fd);
324
325 return ret;
326 }
327