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-rw-r--r--Documentation/usb/gadget_hid.txt445
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+
+ Linux USB HID gadget driver
+
+Introduction
+
+ The HID Gadget driver provides emulation of USB Human Interface
+ Devices (HID). The basic HID handling is done in the kernel,
+ and HID reports can be sent/received through I/O on the
+ /dev/hidgX character devices.
+
+ For more details about HID, see the developer page on
+ http://www.usb.org/developers/hidpage/
+
+Configuration
+
+ g_hid is a platform driver, so to use it you need to add
+ struct platform_device(s) to your platform code defining the
+ HID function descriptors you want to use - E.G. something
+ like:
+
+#include <linux/platform_device.h>
+#include <linux/usb/g_hid.h>
+
+/* hid descriptor for a keyboard */
+static struct hidg_func_descriptor my_hid_data = {
+ .subclass = 0, /* No subclass */
+ .protocol = 1, /* Keyboard */
+ .report_length = 8,
+ .report_desc_length = 63,
+ .report_desc = {
+ 0x05, 0x01, /* USAGE_PAGE (Generic Desktop) */
+ 0x09, 0x06, /* USAGE (Keyboard) */
+ 0xa1, 0x01, /* COLLECTION (Application) */
+ 0x05, 0x07, /* USAGE_PAGE (Keyboard) */
+ 0x19, 0xe0, /* USAGE_MINIMUM (Keyboard LeftControl) */
+ 0x29, 0xe7, /* USAGE_MAXIMUM (Keyboard Right GUI) */
+ 0x15, 0x00, /* LOGICAL_MINIMUM (0) */
+ 0x25, 0x01, /* LOGICAL_MAXIMUM (1) */
+ 0x75, 0x01, /* REPORT_SIZE (1) */
+ 0x95, 0x08, /* REPORT_COUNT (8) */
+ 0x81, 0x02, /* INPUT (Data,Var,Abs) */
+ 0x95, 0x01, /* REPORT_COUNT (1) */
+ 0x75, 0x08, /* REPORT_SIZE (8) */
+ 0x81, 0x03, /* INPUT (Cnst,Var,Abs) */
+ 0x95, 0x05, /* REPORT_COUNT (5) */
+ 0x75, 0x01, /* REPORT_SIZE (1) */
+ 0x05, 0x08, /* USAGE_PAGE (LEDs) */
+ 0x19, 0x01, /* USAGE_MINIMUM (Num Lock) */
+ 0x29, 0x05, /* USAGE_MAXIMUM (Kana) */
+ 0x91, 0x02, /* OUTPUT (Data,Var,Abs) */
+ 0x95, 0x01, /* REPORT_COUNT (1) */
+ 0x75, 0x03, /* REPORT_SIZE (3) */
+ 0x91, 0x03, /* OUTPUT (Cnst,Var,Abs) */
+ 0x95, 0x06, /* REPORT_COUNT (6) */
+ 0x75, 0x08, /* REPORT_SIZE (8) */
+ 0x15, 0x00, /* LOGICAL_MINIMUM (0) */
+ 0x25, 0x65, /* LOGICAL_MAXIMUM (101) */
+ 0x05, 0x07, /* USAGE_PAGE (Keyboard) */
+ 0x19, 0x00, /* USAGE_MINIMUM (Reserved) */
+ 0x29, 0x65, /* USAGE_MAXIMUM (Keyboard Application) */
+ 0x81, 0x00, /* INPUT (Data,Ary,Abs) */
+ 0xc0 /* END_COLLECTION */
+ }
+};
+
+static struct platform_device my_hid = {
+ .name = "hidg",
+ .id = 0,
+ .num_resources = 0,
+ .resource = 0,
+ .dev.platform_data = &my_hid_data,
+};
+
+ You can add as many HID functions as you want, only limited by
+ the amount of interrupt endpoints your gadget driver supports.
+
+Send and receive HID reports
+
+ HID reports can be sent/received using read/write on the
+ /dev/hidgX character devices. See below for an example program
+ to do this.
+
+ hid_gadget_test is a small interactive program to test the HID
+ gadget driver. To use, point it at a hidg device and set the
+ device type (keyboard / mouse / joystick) - E.G.:
+
+ # hid_gadget_test /dev/hidg0 keyboard
+
+ You are now in the prompt of hid_gadget_test. You can type any
+ combination of options and values. Available options and
+ values are listed at program start. In keyboard mode you can
+ send up to six values.
+
+ For example type: g i s t r --left-shift
+
+ Hit return and the corresponding report will be sent by the
+ HID gadget.
+
+ Another interesting example is the caps lock test. Type
+ -–caps-lock and hit return. A report is then sent by the
+ gadget and you should receive the host answer, corresponding
+ to the caps lock LED status.
+
+ --caps-lock
+ recv report:2
+
+ With this command:
+
+ # hid_gadget_test /dev/hidg1 mouse
+
+ You can test the mouse emulation. Values are two signed numbers.
+
+
+Sample code
+
+/* hid_gadget_test */
+
+#include <pthread.h>
+#include <string.h>
+#include <stdio.h>
+#include <ctype.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#define BUF_LEN 512
+
+struct options {
+ const char *opt;
+ unsigned char val;
+};
+
+static struct options kmod[] = {
+ {.opt = "--left-ctrl", .val = 0x01},
+ {.opt = "--right-ctrl", .val = 0x10},
+ {.opt = "--left-shift", .val = 0x02},
+ {.opt = "--right-shift", .val = 0x20},
+ {.opt = "--left-alt", .val = 0x04},
+ {.opt = "--right-alt", .val = 0x40},
+ {.opt = "--left-meta", .val = 0x08},
+ {.opt = "--right-meta", .val = 0x80},
+ {.opt = NULL}
+};
+
+static struct options kval[] = {
+ {.opt = "--return", .val = 0x28},
+ {.opt = "--esc", .val = 0x29},
+ {.opt = "--bckspc", .val = 0x2a},
+ {.opt = "--tab", .val = 0x2b},
+ {.opt = "--spacebar", .val = 0x2c},
+ {.opt = "--caps-lock", .val = 0x39},
+ {.opt = "--f1", .val = 0x3a},
+ {.opt = "--f2", .val = 0x3b},
+ {.opt = "--f3", .val = 0x3c},
+ {.opt = "--f4", .val = 0x3d},
+ {.opt = "--f5", .val = 0x3e},
+ {.opt = "--f6", .val = 0x3f},
+ {.opt = "--f7", .val = 0x40},
+ {.opt = "--f8", .val = 0x41},
+ {.opt = "--f9", .val = 0x42},
+ {.opt = "--f10", .val = 0x43},
+ {.opt = "--f11", .val = 0x44},
+ {.opt = "--f12", .val = 0x45},
+ {.opt = "--insert", .val = 0x49},
+ {.opt = "--home", .val = 0x4a},
+ {.opt = "--pageup", .val = 0x4b},
+ {.opt = "--del", .val = 0x4c},
+ {.opt = "--end", .val = 0x4d},
+ {.opt = "--pagedown", .val = 0x4e},
+ {.opt = "--right", .val = 0x4f},
+ {.opt = "--left", .val = 0x50},
+ {.opt = "--down", .val = 0x51},
+ {.opt = "--kp-enter", .val = 0x58},
+ {.opt = "--up", .val = 0x52},
+ {.opt = "--num-lock", .val = 0x53},
+ {.opt = NULL}
+};
+
+int keyboard_fill_report(char report[8], char buf[BUF_LEN], int *hold)
+{
+ char *tok = strtok(buf, " ");
+ int key = 0;
+ int i = 0;
+
+ for (; tok != NULL; tok = strtok(NULL, " ")) {
+
+ if (strcmp(tok, "--quit") == 0)
+ return -1;
+
+ if (strcmp(tok, "--hold") == 0) {
+ *hold = 1;
+ continue;
+ }
+
+ if (key < 6) {
+ for (i = 0; kval[i].opt != NULL; i++)
+ if (strcmp(tok, kval[i].opt) == 0) {
+ report[2 + key++] = kval[i].val;
+ break;
+ }
+ if (kval[i].opt != NULL)
+ continue;
+ }
+
+ if (key < 6)
+ if (islower(tok[0])) {
+ report[2 + key++] = (tok[0] - ('a' - 0x04));
+ continue;
+ }
+
+ for (i = 0; kmod[i].opt != NULL; i++)
+ if (strcmp(tok, kmod[i].opt) == 0) {
+ report[0] = report[0] | kmod[i].val;
+ break;
+ }
+ if (kmod[i].opt != NULL)
+ continue;
+
+ if (key < 6)
+ fprintf(stderr, "unknown option: %s\n", tok);
+ }
+ return 8;
+}
+
+static struct options mmod[] = {
+ {.opt = "--b1", .val = 0x01},
+ {.opt = "--b2", .val = 0x02},
+ {.opt = "--b3", .val = 0x04},
+ {.opt = NULL}
+};
+
+int mouse_fill_report(char report[8], char buf[BUF_LEN], int *hold)
+{
+ char *tok = strtok(buf, " ");
+ int mvt = 0;
+ int i = 0;
+ for (; tok != NULL; tok = strtok(NULL, " ")) {
+
+ if (strcmp(tok, "--quit") == 0)
+ return -1;
+
+ if (strcmp(tok, "--hold") == 0) {
+ *hold = 1;
+ continue;
+ }
+
+ for (i = 0; mmod[i].opt != NULL; i++)
+ if (strcmp(tok, mmod[i].opt) == 0) {
+ report[0] = report[0] | mmod[i].val;
+ break;
+ }
+ if (mmod[i].opt != NULL)
+ continue;
+
+ if (!(tok[0] == '-' && tok[1] == '-') && mvt < 2) {
+ errno = 0;
+ report[1 + mvt++] = (char)strtol(tok, NULL, 0);
+ if (errno != 0) {
+ fprintf(stderr, "Bad value:'%s'\n", tok);
+ report[1 + mvt--] = 0;
+ }
+ continue;
+ }
+
+ fprintf(stderr, "unknown option: %s\n", tok);
+ }
+ return 3;
+}
+
+static struct options jmod[] = {
+ {.opt = "--b1", .val = 0x10},
+ {.opt = "--b2", .val = 0x20},
+ {.opt = "--b3", .val = 0x40},
+ {.opt = "--b4", .val = 0x80},
+ {.opt = "--hat1", .val = 0x00},
+ {.opt = "--hat2", .val = 0x01},
+ {.opt = "--hat3", .val = 0x02},
+ {.opt = "--hat4", .val = 0x03},
+ {.opt = "--hatneutral", .val = 0x04},
+ {.opt = NULL}
+};
+
+int joystick_fill_report(char report[8], char buf[BUF_LEN], int *hold)
+{
+ char *tok = strtok(buf, " ");
+ int mvt = 0;
+ int i = 0;
+
+ *hold = 1;
+
+ /* set default hat position: neutral */
+ report[3] = 0x04;
+
+ for (; tok != NULL; tok = strtok(NULL, " ")) {
+
+ if (strcmp(tok, "--quit") == 0)
+ return -1;
+
+ for (i = 0; jmod[i].opt != NULL; i++)
+ if (strcmp(tok, jmod[i].opt) == 0) {
+ report[3] = (report[3] & 0xF0) | jmod[i].val;
+ break;
+ }
+ if (jmod[i].opt != NULL)
+ continue;
+
+ if (!(tok[0] == '-' && tok[1] == '-') && mvt < 3) {
+ errno = 0;
+ report[mvt++] = (char)strtol(tok, NULL, 0);
+ if (errno != 0) {
+ fprintf(stderr, "Bad value:'%s'\n", tok);
+ report[mvt--] = 0;
+ }
+ continue;
+ }
+
+ fprintf(stderr, "unknown option: %s\n", tok);
+ }
+ return 4;
+}
+
+void print_options(char c)
+{
+ int i = 0;
+
+ if (c == 'k') {
+ printf(" keyboard options:\n"
+ " --hold\n");
+ for (i = 0; kmod[i].opt != NULL; i++)
+ printf("\t\t%s\n", kmod[i].opt);
+ printf("\n keyboard values:\n"
+ " [a-z] or\n");
+ for (i = 0; kval[i].opt != NULL; i++)
+ printf("\t\t%-8s%s", kval[i].opt, i % 2 ? "\n" : "");
+ printf("\n");
+ } else if (c == 'm') {
+ printf(" mouse options:\n"
+ " --hold\n");
+ for (i = 0; mmod[i].opt != NULL; i++)
+ printf("\t\t%s\n", mmod[i].opt);
+ printf("\n mouse values:\n"
+ " Two signed numbers\n"
+ "--quit to close\n");
+ } else {
+ printf(" joystick options:\n");
+ for (i = 0; jmod[i].opt != NULL; i++)
+ printf("\t\t%s\n", jmod[i].opt);
+ printf("\n joystick values:\n"
+ " three signed numbers\n"
+ "--quit to close\n");
+ }
+}
+
+int main(int argc, const char *argv[])
+{
+ const char *filename = NULL;
+ int fd = 0;
+ char buf[BUF_LEN];
+ int cmd_len;
+ char report[8];
+ int to_send = 8;
+ int hold = 0;
+ fd_set rfds;
+ int retval, i;
+
+ if (argc < 3) {
+ fprintf(stderr, "Usage: %s devname mouse|keyboard|joystick\n",
+ argv[0]);
+ return 1;
+ }
+
+ if (argv[2][0] != 'k' && argv[2][0] != 'm' && argv[2][0] != 'j')
+ return 2;
+
+ filename = argv[1];
+
+ if ((fd = open(filename, O_RDWR, 0666)) == -1) {
+ perror(filename);
+ return 3;
+ }
+
+ print_options(argv[2][0]);
+
+ while (42) {
+
+ FD_ZERO(&rfds);
+ FD_SET(STDIN_FILENO, &rfds);
+ FD_SET(fd, &rfds);
+
+ retval = select(fd + 1, &rfds, NULL, NULL, NULL);
+ if (retval == -1 && errno == EINTR)
+ continue;
+ if (retval < 0) {
+ perror("select()");
+ return 4;
+ }
+
+ if (FD_ISSET(fd, &rfds)) {
+ cmd_len = read(fd, buf, BUF_LEN - 1);
+ printf("recv report:");
+ for (i = 0; i < cmd_len; i++)
+ printf(" %02x", buf[i]);
+ printf("\n");
+ }
+
+ if (FD_ISSET(STDIN_FILENO, &rfds)) {
+ memset(report, 0x0, sizeof(report));
+ cmd_len = read(STDIN_FILENO, buf, BUF_LEN - 1);
+
+ if (cmd_len == 0)
+ break;
+
+ buf[cmd_len - 1] = '\0';
+ hold = 0;
+
+ memset(report, 0x0, sizeof(report));
+ if (argv[2][0] == 'k')
+ to_send = keyboard_fill_report(report, buf, &hold);
+ else if (argv[2][0] == 'm')
+ to_send = mouse_fill_report(report, buf, &hold);
+ else
+ to_send = joystick_fill_report(report, buf, &hold);
+
+ if (to_send == -1)
+ break;
+
+ if (write(fd, report, to_send) != to_send) {
+ perror(filename);
+ return 5;
+ }
+ if (!hold) {
+ memset(report, 0x0, sizeof(report));
+ if (write(fd, report, to_send) != to_send) {
+ perror(filename);
+ return 6;
+ }
+ }
+ }
+ }
+
+ close(fd);
+ return 0;
+}
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