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+/*
+ * UHID Example
+ *
+ * Copyright (c) 2012 David Herrmann <dh.herrmann@googlemail.com>
+ *
+ * The code may be used by anyone for any purpose,
+ * and can serve as a starting point for developing
+ * applications using uhid.
+ */
+
+/* UHID Example
+ * This example emulates a basic 3 buttons mouse with wheel over UHID. Run this
+ * program as root and then use the following keys to control the mouse:
+ * q: Quit the application
+ * 1: Toggle left button (down, up, ...)
+ * 2: Toggle right button
+ * 3: Toggle middle button
+ * a: Move mouse left
+ * d: Move mouse right
+ * w: Move mouse up
+ * s: Move mouse down
+ * r: Move wheel up
+ * f: Move wheel down
+ *
+ * If uhid is not available as /dev/uhid, then you can pass a different path as
+ * first argument.
+ * If <linux/uhid.h> is not installed in /usr, then compile this with:
+ * gcc -o ./uhid_test -Wall -I./include ./samples/uhid/uhid-example.c
+ * And ignore the warning about kernel headers. However, it is recommended to
+ * use the installed uhid.h if available.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <termios.h>
+#include <unistd.h>
+#include <linux/uhid.h>
+
+/* HID Report Desciptor
+ * We emulate a basic 3 button mouse with wheel. This is the report-descriptor
+ * as the kernel will parse it:
+ *
+ * INPUT[INPUT]
+ * Field(0)
+ * Physical(GenericDesktop.Pointer)
+ * Application(GenericDesktop.Mouse)
+ * Usage(3)
+ * Button.0001
+ * Button.0002
+ * Button.0003
+ * Logical Minimum(0)
+ * Logical Maximum(1)
+ * Report Size(1)
+ * Report Count(3)
+ * Report Offset(0)
+ * Flags( Variable Absolute )
+ * Field(1)
+ * Physical(GenericDesktop.Pointer)
+ * Application(GenericDesktop.Mouse)
+ * Usage(3)
+ * GenericDesktop.X
+ * GenericDesktop.Y
+ * GenericDesktop.Wheel
+ * Logical Minimum(-128)
+ * Logical Maximum(127)
+ * Report Size(8)
+ * Report Count(3)
+ * Report Offset(8)
+ * Flags( Variable Relative )
+ *
+ * This is the mapping that we expect:
+ * Button.0001 ---> Key.LeftBtn
+ * Button.0002 ---> Key.RightBtn
+ * Button.0003 ---> Key.MiddleBtn
+ * GenericDesktop.X ---> Relative.X
+ * GenericDesktop.Y ---> Relative.Y
+ * GenericDesktop.Wheel ---> Relative.Wheel
+ *
+ * This information can be verified by reading /sys/kernel/debug/hid/<dev>/rdesc
+ * This file should print the same information as showed above.
+ */
+
+static unsigned char rdesc[] = {
+ 0x05, 0x01, 0x09, 0x02, 0xa1, 0x01, 0x09, 0x01,
+ 0xa1, 0x00, 0x05, 0x09, 0x19, 0x01, 0x29, 0x03,
+ 0x15, 0x00, 0x25, 0x01, 0x95, 0x03, 0x75, 0x01,
+ 0x81, 0x02, 0x95, 0x01, 0x75, 0x05, 0x81, 0x01,
+ 0x05, 0x01, 0x09, 0x30, 0x09, 0x31, 0x09, 0x38,
+ 0x15, 0x80, 0x25, 0x7f, 0x75, 0x08, 0x95, 0x03,
+ 0x81, 0x06, 0xc0, 0xc0,
+};
+
+static int uhid_write(int fd, const struct uhid_event *ev)
+{
+ ssize_t ret;
+
+ ret = write(fd, ev, sizeof(*ev));
+ if (ret < 0) {
+ fprintf(stderr, "Cannot write to uhid: %m\n");
+ return -errno;
+ } else if (ret != sizeof(*ev)) {
+ fprintf(stderr, "Wrong size written to uhid: %ld != %lu\n",
+ ret, sizeof(ev));
+ return -EFAULT;
+ } else {
+ return 0;
+ }
+}
+
+static int create(int fd)
+{
+ struct uhid_event ev;
+
+ memset(&ev, 0, sizeof(ev));
+ ev.type = UHID_CREATE;
+ strcpy((char*)ev.u.create.name, "test-uhid-device");
+ ev.u.create.rd_data = rdesc;
+ ev.u.create.rd_size = sizeof(rdesc);
+ ev.u.create.bus = BUS_USB;
+ ev.u.create.vendor = 0x15d9;
+ ev.u.create.product = 0x0a37;
+ ev.u.create.version = 0;
+ ev.u.create.country = 0;
+
+ return uhid_write(fd, &ev);
+}
+
+static void destroy(int fd)
+{
+ struct uhid_event ev;
+
+ memset(&ev, 0, sizeof(ev));
+ ev.type = UHID_DESTROY;
+
+ uhid_write(fd, &ev);
+}
+
+static int event(int fd)
+{
+ struct uhid_event ev;
+ ssize_t ret;
+
+ memset(&ev, 0, sizeof(ev));
+ ret = read(fd, &ev, sizeof(ev));
+ if (ret == 0) {
+ fprintf(stderr, "Read HUP on uhid-cdev\n");
+ return -EFAULT;
+ } else if (ret < 0) {
+ fprintf(stderr, "Cannot read uhid-cdev: %m\n");
+ return -errno;
+ } else if (ret != sizeof(ev)) {
+ fprintf(stderr, "Invalid size read from uhid-dev: %ld != %lu\n",
+ ret, sizeof(ev));
+ return -EFAULT;
+ }
+
+ switch (ev.type) {
+ case UHID_START:
+ fprintf(stderr, "UHID_START from uhid-dev\n");
+ break;
+ case UHID_STOP:
+ fprintf(stderr, "UHID_STOP from uhid-dev\n");
+ break;
+ case UHID_OPEN:
+ fprintf(stderr, "UHID_OPEN from uhid-dev\n");
+ break;
+ case UHID_CLOSE:
+ fprintf(stderr, "UHID_CLOSE from uhid-dev\n");
+ break;
+ case UHID_OUTPUT:
+ fprintf(stderr, "UHID_OUTPUT from uhid-dev\n");
+ break;
+ case UHID_OUTPUT_EV:
+ fprintf(stderr, "UHID_OUTPUT_EV from uhid-dev\n");
+ break;
+ default:
+ fprintf(stderr, "Invalid event from uhid-dev: %u\n", ev.type);
+ }
+
+ return 0;
+}
+
+static bool btn1_down;
+static bool btn2_down;
+static bool btn3_down;
+static signed char abs_hor;
+static signed char abs_ver;
+static signed char wheel;
+
+static int send_event(int fd)
+{
+ struct uhid_event ev;
+
+ memset(&ev, 0, sizeof(ev));
+ ev.type = UHID_INPUT;
+ ev.u.input.size = 4;
+
+ if (btn1_down)
+ ev.u.input.data[0] |= 0x1;
+ if (btn2_down)
+ ev.u.input.data[0] |= 0x2;
+ if (btn3_down)
+ ev.u.input.data[0] |= 0x4;
+
+ ev.u.input.data[1] = abs_hor;
+ ev.u.input.data[2] = abs_ver;
+ ev.u.input.data[3] = wheel;
+
+ return uhid_write(fd, &ev);
+}
+
+static int keyboard(int fd)
+{
+ char buf[128];
+ ssize_t ret, i;
+
+ ret = read(STDIN_FILENO, buf, sizeof(buf));
+ if (ret == 0) {
+ fprintf(stderr, "Read HUP on stdin\n");
+ return -EFAULT;
+ } else if (ret < 0) {
+ fprintf(stderr, "Cannot read stdin: %m\n");
+ return -errno;
+ }
+
+ for (i = 0; i < ret; ++i) {
+ switch (buf[i]) {
+ case '1':
+ btn1_down = !btn1_down;
+ ret = send_event(fd);
+ if (ret)
+ return ret;
+ break;
+ case '2':
+ btn2_down = !btn2_down;
+ ret = send_event(fd);
+ if (ret)
+ return ret;
+ break;
+ case '3':
+ btn3_down = !btn3_down;
+ ret = send_event(fd);
+ if (ret)
+ return ret;
+ break;
+ case 'a':
+ abs_hor = -20;
+ ret = send_event(fd);
+ abs_hor = 0;
+ if (ret)
+ return ret;
+ break;
+ case 'd':
+ abs_hor = 20;
+ ret = send_event(fd);
+ abs_hor = 0;
+ if (ret)
+ return ret;
+ break;
+ case 'w':
+ abs_ver = -20;
+ ret = send_event(fd);
+ abs_ver = 0;
+ if (ret)
+ return ret;
+ break;
+ case 's':
+ abs_ver = 20;
+ ret = send_event(fd);
+ abs_ver = 0;
+ if (ret)
+ return ret;
+ break;
+ case 'r':
+ wheel = 1;
+ ret = send_event(fd);
+ wheel = 0;
+ if (ret)
+ return ret;
+ break;
+ case 'f':
+ wheel = -1;
+ ret = send_event(fd);
+ wheel = 0;
+ if (ret)
+ return ret;
+ break;
+ case 'q':
+ return -ECANCELED;
+ default:
+ fprintf(stderr, "Invalid input: %c\n", buf[i]);
+ }
+ }
+
+ return 0;
+}
+
+int main(int argc, char **argv)
+{
+ int fd;
+ const char *path = "/dev/uhid";
+ struct pollfd pfds[2];
+ int ret;
+ struct termios state;
+
+ ret = tcgetattr(STDIN_FILENO, &state);
+ if (ret) {
+ fprintf(stderr, "Cannot get tty state\n");
+ } else {
+ state.c_lflag &= ~ICANON;
+ state.c_cc[VMIN] = 1;
+ ret = tcsetattr(STDIN_FILENO, TCSANOW, &state);
+ if (ret)
+ fprintf(stderr, "Cannot set tty state\n");
+ }
+
+ if (argc >= 2) {
+ if (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help")) {
+ fprintf(stderr, "Usage: %s [%s]\n", argv[0], path);
+ return EXIT_SUCCESS;
+ } else {
+ path = argv[1];
+ }
+ }
+
+ fprintf(stderr, "Open uhid-cdev %s\n", path);
+ fd = open(path, O_RDWR | O_CLOEXEC);
+ if (fd < 0) {
+ fprintf(stderr, "Cannot open uhid-cdev %s: %m\n", path);
+ return EXIT_FAILURE;
+ }
+
+ fprintf(stderr, "Create uhid device\n");
+ ret = create(fd);
+ if (ret) {
+ close(fd);
+ return EXIT_FAILURE;
+ }
+
+ pfds[0].fd = STDIN_FILENO;
+ pfds[0].events = POLLIN;
+ pfds[1].fd = fd;
+ pfds[1].events = POLLIN;
+
+ fprintf(stderr, "Press 'q' to quit...\n");
+ while (1) {
+ ret = poll(pfds, 2, -1);
+ if (ret < 0) {
+ fprintf(stderr, "Cannot poll for fds: %m\n");
+ break;
+ }
+ if (pfds[0].revents & POLLHUP) {
+ fprintf(stderr, "Received HUP on stdin\n");
+ break;
+ }
+ if (pfds[1].revents & POLLHUP) {
+ fprintf(stderr, "Received HUP on uhid-cdev\n");
+ break;
+ }
+
+ if (pfds[0].revents & POLLIN) {
+ ret = keyboard(fd);
+ if (ret)
+ break;
+ }
+ if (pfds[1].revents & POLLIN) {
+ ret = event(fd);
+ if (ret)
+ break;
+ }
+ }
+
+ fprintf(stderr, "Destroy uhid device\n");
+ destroy(fd);
+ return EXIT_SUCCESS;
+}
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