Documentation/usb/gadget_hid.txt

   1
   2                      Linux USB HID gadget driver
   3
   4 Introduction
   5
   6         The HID Gadget driver provides emulation of USB Human Interface
   7         Devices (HID). The basic HID handling is done in the kernel,
   8         and HID reports can be sent/received through I/O on the
   9         /dev/hidgX character devices.
  10
  11         For more details about HID, see the developer page on
  12         http://www.usb.org/developers/hidpage/
  13
  14 Configuration
  15
  16         g_hid is a platform driver, so to use it you need to add
  17         struct platform_device(s) to your platform code defining the
  18         HID function descriptors you want to use - E.G. something
  19         like:
  20
  21 #include <linux/platform_device.h>
  22 #include <linux/usb/g_hid.h>
  23
  24 /* hid descriptor for a keyboard */
  25 static struct hidg_func_descriptor my_hid_data = {
  26         .subclass               = 0, /* No subclass */
  27         .protocol               = 1, /* Keyboard */
  28         .report_length          = 8,
  29         .report_desc_length     = 63,
  30         .report_desc            = {
  31                 0x05, 0x01,     /* USAGE_PAGE (Generic Desktop)           */
  32                 0x09, 0x06,     /* USAGE (Keyboard)                       */
  33                 0xa1, 0x01,     /* COLLECTION (Application)               */
  34                 0x05, 0x07,     /*   USAGE_PAGE (Keyboard)                */
  35                 0x19, 0xe0,     /*   USAGE_MINIMUM (Keyboard LeftControl) */
  36                 0x29, 0xe7,     /*   USAGE_MAXIMUM (Keyboard Right GUI)   */
  37                 0x15, 0x00,     /*   LOGICAL_MINIMUM (0)                  */
  38                 0x25, 0x01,     /*   LOGICAL_MAXIMUM (1)                  */
  39                 0x75, 0x01,     /*   REPORT_SIZE (1)                      */
  40                 0x95, 0x08,     /*   REPORT_COUNT (8)                     */
  41                 0x81, 0x02,     /*   INPUT (Data,Var,Abs)                 */
  42                 0x95, 0x01,     /*   REPORT_COUNT (1)                     */
  43                 0x75, 0x08,     /*   REPORT_SIZE (8)                      */
  44                 0x81, 0x03,     /*   INPUT (Cnst,Var,Abs)                 */
  45                 0x95, 0x05,     /*   REPORT_COUNT (5)                     */
  46                 0x75, 0x01,     /*   REPORT_SIZE (1)                      */
  47                 0x05, 0x08,     /*   USAGE_PAGE (LEDs)                    */
  48                 0x19, 0x01,     /*   USAGE_MINIMUM (Num Lock)             */
  49                 0x29, 0x05,     /*   USAGE_MAXIMUM (Kana)                 */
  50                 0x91, 0x02,     /*   OUTPUT (Data,Var,Abs)                */
  51                 0x95, 0x01,     /*   REPORT_COUNT (1)                     */
  52                 0x75, 0x03,     /*   REPORT_SIZE (3)                      */
  53                 0x91, 0x03,     /*   OUTPUT (Cnst,Var,Abs)                */
  54                 0x95, 0x06,     /*   REPORT_COUNT (6)                     */
  55                 0x75, 0x08,     /*   REPORT_SIZE (8)                      */
  56                 0x15, 0x00,     /*   LOGICAL_MINIMUM (0)                  */
  57                 0x25, 0x65,     /*   LOGICAL_MAXIMUM (101)                */
  58                 0x05, 0x07,     /*   USAGE_PAGE (Keyboard)                */
  59                 0x19, 0x00,     /*   USAGE_MINIMUM (Reserved)             */
  60                 0x29, 0x65,     /*   USAGE_MAXIMUM (Keyboard Application) */
  61                 0x81, 0x00,     /*   INPUT (Data,Ary,Abs)                 */
  62                 0xc0            /* END_COLLECTION                         */
  63         }
  64 };
  65
  66 static struct platform_device my_hid = {
  67         .name                   = "hidg",
  68         .id                     = 0,
  69         .num_resources          = 0,
  70         .resource               = 0,
  71         .dev.platform_data      = &my_hid_data,
  72 };
  73
  74         You can add as many HID functions as you want, only limited by
  75         the amount of interrupt endpoints your gadget driver supports.
  76
  77 Send and receive HID reports
  78
  79         HID reports can be sent/received using read/write on the
  80         /dev/hidgX character devices. See below for an example program
  81         to do this.
  82
  83         hid_gadget_test is a small interactive program to test the HID
  84         gadget driver. To use, point it at a hidg device and set the
  85         device type (keyboard / mouse / joystick) - E.G.:
  86
  87                 # hid_gadget_test /dev/hidg0 keyboard
  88
  89         You are now in the prompt of hid_gadget_test. You can type any
  90         combination of options and values. Available options and
  91         values are listed at program start. In keyboard mode you can
  92         send up to six values.
  93
  94         For example type: g i s t r --left-shift
  95
  96         Hit return and the corresponding report will be sent by the
  97         HID gadget.
  98
  99         Another interesting example is the caps lock test. Type
 100         -–caps-lock and hit return. A report is then sent by the
 101         gadget and you should receive the host answer, corresponding
 102         to the caps lock LED status.
 103
 104                 --caps-lock
 105                 recv report:2
 106
 107         With this command:
 108
 109                 # hid_gadget_test /dev/hidg1 mouse
 110
 111         You can test the mouse emulation. Values are two signed numbers.
 112
 113
 114 Sample code
 115
 116 /* hid_gadget_test */
 117
 118 #include <pthread.h>
 119 #include <string.h>
 120 #include <stdio.h>
 121 #include <ctype.h>
 122 #include <fcntl.h>
 123 #include <errno.h>
 124 #include <stdio.h>
 125 #include <stdlib.h>
 126 #include <unistd.h>
 127
 128 #define BUF_LEN 512
 129
 130 struct options {
 131         const char    *opt;
 132         unsigned char val;
 133 };
 134
 135 static struct options kmod[] = {
 136         {.opt = "--left-ctrl",          .val = 0x01},
 137         {.opt = "--right-ctrl",         .val = 0x10},
 138         {.opt = "--left-shift",         .val = 0x02},
 139         {.opt = "--right-shift",        .val = 0x20},
 140         {.opt = "--left-alt",           .val = 0x04},
 141         {.opt = "--right-alt",          .val = 0x40},
 142         {.opt = "--left-meta",          .val = 0x08},
 143         {.opt = "--right-meta",         .val = 0x80},
 144         {.opt = NULL}
 145 };
 146
 147 static struct options kval[] = {
 148         {.opt = "--return",     .val = 0x28},
 149         {.opt = "--esc",        .val = 0x29},
 150         {.opt = "--bckspc",     .val = 0x2a},
 151         {.opt = "--tab",        .val = 0x2b},
 152         {.opt = "--spacebar",   .val = 0x2c},
 153         {.opt = "--caps-lock",  .val = 0x39},
 154         {.opt = "--f1",         .val = 0x3a},
 155         {.opt = "--f2",         .val = 0x3b},
 156         {.opt = "--f3",         .val = 0x3c},
 157         {.opt = "--f4",         .val = 0x3d},
 158         {.opt = "--f5",         .val = 0x3e},
 159         {.opt = "--f6",         .val = 0x3f},
 160         {.opt = "--f7",         .val = 0x40},
 161         {.opt = "--f8",         .val = 0x41},
 162         {.opt = "--f9",         .val = 0x42},
 163         {.opt = "--f10",        .val = 0x43},
 164         {.opt = "--f11",        .val = 0x44},
 165         {.opt = "--f12",        .val = 0x45},
 166         {.opt = "--insert",     .val = 0x49},
 167         {.opt = "--home",       .val = 0x4a},
 168         {.opt = "--pageup",     .val = 0x4b},
 169         {.opt = "--del",        .val = 0x4c},
 170         {.opt = "--end",        .val = 0x4d},
 171         {.opt = "--pagedown",   .val = 0x4e},
 172         {.opt = "--right",      .val = 0x4f},
 173         {.opt = "--left",       .val = 0x50},
 174         {.opt = "--down",       .val = 0x51},
 175         {.opt = "--kp-enter",   .val = 0x58},
 176         {.opt = "--up",         .val = 0x52},
 177         {.opt = "--num-lock",   .val = 0x53},
 178         {.opt = NULL}
 179 };
 180
 181 int keyboard_fill_report(char report[8], char buf[BUF_LEN], int *hold)
 182 {
 183         char *tok = strtok(buf, " ");
 184         int key = 0;
 185         int i = 0;
 186
 187         for (; tok != NULL; tok = strtok(NULL, " ")) {
 188
 189                 if (strcmp(tok, "--quit") == 0)
 190                         return -1;
 191
 192                 if (strcmp(tok, "--hold") == 0) {
 193                         *hold = 1;
 194                         continue;
 195                 }
 196
 197                 if (key < 6) {
 198                         for (i = 0; kval[i].opt != NULL; i++)
 199                                 if (strcmp(tok, kval[i].opt) == 0) {
 200                                         report[2 + key++] = kval[i].val;
 201                                         break;
 202                                 }
 203                         if (kval[i].opt != NULL)
 204                                 continue;
 205                 }
 206
 207                 if (key < 6)
 208                         if (islower(tok[0])) {
 209                                 report[2 + key++] = (tok[0] - ('a' - 0x04));
 210                                 continue;
 211                         }
 212
 213                 for (i = 0; kmod[i].opt != NULL; i++)
 214                         if (strcmp(tok, kmod[i].opt) == 0) {
 215                                 report[0] = report[0] | kmod[i].val;
 216                                 break;
 217                         }
 218                 if (kmod[i].opt != NULL)
 219                         continue;
 220
 221                 if (key < 6)
 222                         fprintf(stderr, "unknown option: %s\n", tok);
 223         }
 224         return 8;
 225 }
 226
 227 static struct options mmod[] = {
 228         {.opt = "--b1", .val = 0x01},
 229         {.opt = "--b2", .val = 0x02},
 230         {.opt = "--b3", .val = 0x04},
 231         {.opt = NULL}
 232 };
 233
 234 int mouse_fill_report(char report[8], char buf[BUF_LEN], int *hold)
 235 {
 236         char *tok = strtok(buf, " ");
 237         int mvt = 0;
 238         int i = 0;
 239         for (; tok != NULL; tok = strtok(NULL, " ")) {
 240
 241                 if (strcmp(tok, "--quit") == 0)
 242                         return -1;
 243
 244                 if (strcmp(tok, "--hold") == 0) {
 245                         *hold = 1;
 246                         continue;
 247                 }
 248
 249                 for (i = 0; mmod[i].opt != NULL; i++)
 250                         if (strcmp(tok, mmod[i].opt) == 0) {
 251                                 report[0] = report[0] | mmod[i].val;
 252                                 break;
 253                         }
 254                 if (mmod[i].opt != NULL)
 255                         continue;
 256
 257                 if (!(tok[0] == '-' && tok[1] == '-') && mvt < 2) {
 258                         errno = 0;
 259                         report[1 + mvt++] = (char)strtol(tok, NULL, 0);
 260                         if (errno != 0) {
 261                                 fprintf(stderr, "Bad value:'%s'\n", tok);
 262                                 report[1 + mvt--] = 0;
 263                         }
 264                         continue;
 265                 }
 266
 267                 fprintf(stderr, "unknown option: %s\n", tok);
 268         }
 269         return 3;
 270 }
 271
 272 static struct options jmod[] = {
 273         {.opt = "--b1",         .val = 0x10},
 274         {.opt = "--b2",         .val = 0x20},
 275         {.opt = "--b3",         .val = 0x40},
 276         {.opt = "--b4",         .val = 0x80},
 277         {.opt = "--hat1",       .val = 0x00},
 278         {.opt = "--hat2",       .val = 0x01},
 279         {.opt = "--hat3",       .val = 0x02},
 280         {.opt = "--hat4",       .val = 0x03},
 281         {.opt = "--hatneutral", .val = 0x04},
 282         {.opt = NULL}
 283 };
 284
 285 int joystick_fill_report(char report[8], char buf[BUF_LEN], int *hold)
 286 {
 287         char *tok = strtok(buf, " ");
 288         int mvt = 0;
 289         int i = 0;
 290
 291         *hold = 1;
 292
 293         /* set default hat position: neutral */
 294         report[3] = 0x04;
 295
 296         for (; tok != NULL; tok = strtok(NULL, " ")) {
 297
 298                 if (strcmp(tok, "--quit") == 0)
 299                         return -1;
 300
 301                 for (i = 0; jmod[i].opt != NULL; i++)
 302                         if (strcmp(tok, jmod[i].opt) == 0) {
 303                                 report[3] = (report[3] & 0xF0) | jmod[i].val;
 304                                 break;
 305                         }
 306                 if (jmod[i].opt != NULL)
 307                         continue;
 308
 309                 if (!(tok[0] == '-' && tok[1] == '-') && mvt < 3) {
 310                         errno = 0;
 311                         report[mvt++] = (char)strtol(tok, NULL, 0);
 312                         if (errno != 0) {
 313                                 fprintf(stderr, "Bad value:'%s'\n", tok);
 314                                 report[mvt--] = 0;
 315                         }
 316                         continue;
 317                 }
 318
 319                 fprintf(stderr, "unknown option: %s\n", tok);
 320         }
 321         return 4;
 322 }
 323
 324 void print_options(char c)
 325 {
 326         int i = 0;
 327
 328         if (c == 'k') {
 329                 printf("        keyboard options:\n"
 330                        "                --hold\n");
 331                 for (i = 0; kmod[i].opt != NULL; i++)
 332                         printf("\t\t%s\n", kmod[i].opt);
 333                 printf("\n      keyboard values:\n"
 334                        "                [a-z] or\n");
 335                 for (i = 0; kval[i].opt != NULL; i++)
 336                         printf("\t\t%-8s%s", kval[i].opt, i % 2 ? "\n" : "");
 337                 printf("\n");
 338         } else if (c == 'm') {
 339                 printf("        mouse options:\n"
 340                        "                --hold\n");
 341                 for (i = 0; mmod[i].opt != NULL; i++)
 342                         printf("\t\t%s\n", mmod[i].opt);
 343                 printf("\n      mouse values:\n"
 344                        "                Two signed numbers\n"
 345                        "--quit to close\n");
 346         } else {
 347                 printf("        joystick options:\n");
 348                 for (i = 0; jmod[i].opt != NULL; i++)
 349                         printf("\t\t%s\n", jmod[i].opt);
 350                 printf("\n      joystick values:\n"
 351                        "                three signed numbers\n"
 352                        "--quit to close\n");
 353         }
 354 }
 355
 356 int main(int argc, const char *argv[])
 357 {
 358         const char *filename = NULL;
 359         int fd = 0;
 360         char buf[BUF_LEN];
 361         int cmd_len;
 362         char report[8];
 363         int to_send = 8;
 364         int hold = 0;
 365         fd_set rfds;
 366         int retval, i;
 367
 368         if (argc < 3) {
 369                 fprintf(stderr, "Usage: %s devname mouse|keyboard|joystick\n",
 370                         argv[0]);
 371                 return 1;
 372         }
 373
 374         if (argv[2][0] != 'k' && argv[2][0] != 'm' && argv[2][0] != 'j')
 375           return 2;
 376
 377         filename = argv[1];
 378
 379         if ((fd = open(filename, O_RDWR, 0666)) == -1) {
 380                 perror(filename);
 381                 return 3;
 382         }
 383
 384         print_options(argv[2][0]);
 385
 386         while (42) {
 387
 388                 FD_ZERO(&rfds);
 389                 FD_SET(STDIN_FILENO, &rfds);
 390                 FD_SET(fd, &rfds);
 391
 392                 retval = select(fd + 1, &rfds, NULL, NULL, NULL);
 393                 if (retval == -1 && errno == EINTR)
 394                         continue;
 395                 if (retval < 0) {
 396                         perror("select()");
 397                         return 4;
 398                 }
 399
 400                 if (FD_ISSET(fd, &rfds)) {
 401                         cmd_len = read(fd, buf, BUF_LEN - 1);
 402                         printf("recv report:");
 403                         for (i = 0; i < cmd_len; i++)
 404                                 printf(" %02x", buf[i]);
 405                         printf("\n");
 406                 }
 407
 408                 if (FD_ISSET(STDIN_FILENO, &rfds)) {
 409                         memset(report, 0x0, sizeof(report));
 410                         cmd_len = read(STDIN_FILENO, buf, BUF_LEN - 1);
 411
 412                         if (cmd_len == 0)
 413                                 break;
 414
 415                         buf[cmd_len - 1] = '\0';
 416                         hold = 0;
 417
 418                         memset(report, 0x0, sizeof(report));
 419                         if (argv[2][0] == 'k')
 420                                 to_send = keyboard_fill_report(report, buf, &hold);
 421                         else if (argv[2][0] == 'm')
 422                                 to_send = mouse_fill_report(report, buf, &hold);
 423                         else
 424                                 to_send = joystick_fill_report(report, buf, &hold);
 425
 426                         if (to_send == -1)
 427                                 break;
 428
 429                         if (write(fd, report, to_send) != to_send) {
 430                                 perror(filename);
 431                                 return 5;
 432                         }
 433                         if (!hold) {
 434                                 memset(report, 0x0, sizeof(report));
 435                                 if (write(fd, report, to_send) != to_send) {
 436                                         perror(filename);
 437                                         return 6;
 438                                 }
 439                         }
 440                 }
 441         }
 442
 443         close(fd);
 444         return 0;
 445 }