Eric Lee / smarc-ti-linux-kernel | Embedian Git Server

Commit 5148fa52a12fa1b97c730b2fe321f2aad7ea041c

Authored by David Herrmann 2012-06-10 21:16:27 +0800

Committed by Jiri Kosina 2012-06-18 19:42:03 +0800

HID: uhid: add example program

This adds an example user-space program that emulates a 3 button mouse
with wheel. It detects keyboard presses and moves the mouse accordingly.

It register a fake HID device to feed the raw HID reports into the kernel.
In this example, you could use uinput to get the same result, but this
shows how to get the same behavior with uhid so you don't need HID parsers
in user-space.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Showing 2 changed files with 391 additions and 0 deletions Side-by-side Diff

samples/uhid/Makefile
samples/uhid/uhid-example.c

samples/uhid/Makefile

Diff comments View file @ 5148fa5

	1	+# kbuild trick to avoid linker error. Can be omitted if a module is built.
	2	+obj- := dummy.o
	3	+
	4	+# List of programs to build
	5	+hostprogs-y := uhid-example
	6	+
	7	+# Tell kbuild to always build the programs
	8	+always := $(hostprogs-y)
	9	+
	10	+HOSTCFLAGS_uhid-example.o += -I$(objtree)/usr/include

samples/uhid/uhid-example.c

Diff comments View file @ 5148fa5

	1	+/*
	2	+ * UHID Example
	3	+ *
	4	+ * Copyright (c) 2012 David Herrmann <dh.herrmann@googlemail.com>
	5	+ *
	6	+ * The code may be used by anyone for any purpose,
	7	+ * and can serve as a starting point for developing
	8	+ * applications using uhid.
	9	+ */
	10	+
	11	+/* UHID Example
	12	+ * This example emulates a basic 3 buttons mouse with wheel over UHID. Run this
	13	+ * program as root and then use the following keys to control the mouse:
	14	+ * q: Quit the application
	15	+ * 1: Toggle left button (down, up, ...)
	16	+ * 2: Toggle right button
	17	+ * 3: Toggle middle button
	18	+ * a: Move mouse left
	19	+ * d: Move mouse right
	20	+ * w: Move mouse up
	21	+ * s: Move mouse down
	22	+ * r: Move wheel up
	23	+ * f: Move wheel down
	24	+ *
	25	+ * If uhid is not available as /dev/uhid, then you can pass a different path as
	26	+ * first argument.
	27	+ * If <linux/uhid.h> is not installed in /usr, then compile this with:
	28	+ * gcc -o ./uhid_test -Wall -I./include ./samples/uhid/uhid-example.c
	29	+ * And ignore the warning about kernel headers. However, it is recommended to
	30	+ * use the installed uhid.h if available.
	31	+ */
	32	+
	33	+#include <errno.h>
	34	+#include <fcntl.h>
	35	+#include <poll.h>
	36	+#include <stdbool.h>
	37	+#include <stdio.h>
	38	+#include <stdlib.h>
	39	+#include <string.h>
	40	+#include <termios.h>
	41	+#include <unistd.h>
	42	+#include <linux/uhid.h>
	43	+
	44	+/* HID Report Desciptor
	45	+ * We emulate a basic 3 button mouse with wheel. This is the report-descriptor
	46	+ * as the kernel will parse it:
	47	+ *
	48	+ * INPUT[INPUT]
	49	+ * Field(0)
	50	+ * Physical(GenericDesktop.Pointer)
	51	+ * Application(GenericDesktop.Mouse)
	52	+ * Usage(3)
	53	+ * Button.0001
	54	+ * Button.0002
	55	+ * Button.0003
	56	+ * Logical Minimum(0)
	57	+ * Logical Maximum(1)
	58	+ * Report Size(1)
	59	+ * Report Count(3)
	60	+ * Report Offset(0)
	61	+ * Flags( Variable Absolute )
	62	+ * Field(1)
	63	+ * Physical(GenericDesktop.Pointer)
	64	+ * Application(GenericDesktop.Mouse)
	65	+ * Usage(3)
	66	+ * GenericDesktop.X
	67	+ * GenericDesktop.Y
	68	+ * GenericDesktop.Wheel
	69	+ * Logical Minimum(-128)
	70	+ * Logical Maximum(127)
	71	+ * Report Size(8)
	72	+ * Report Count(3)
	73	+ * Report Offset(8)
	74	+ * Flags( Variable Relative )
	75	+ *
	76	+ * This is the mapping that we expect:
	77	+ * Button.0001 ---> Key.LeftBtn
	78	+ * Button.0002 ---> Key.RightBtn
	79	+ * Button.0003 ---> Key.MiddleBtn
	80	+ * GenericDesktop.X ---> Relative.X
	81	+ * GenericDesktop.Y ---> Relative.Y
	82	+ * GenericDesktop.Wheel ---> Relative.Wheel
	83	+ *
	84	+ * This information can be verified by reading /sys/kernel/debug/hid/<dev>/rdesc
	85	+ * This file should print the same information as showed above.
	86	+ */
	87	+
	88	+static unsigned char rdesc[] = {
	89	+ 0x05, 0x01, 0x09, 0x02, 0xa1, 0x01, 0x09, 0x01,
	90	+ 0xa1, 0x00, 0x05, 0x09, 0x19, 0x01, 0x29, 0x03,
	91	+ 0x15, 0x00, 0x25, 0x01, 0x95, 0x03, 0x75, 0x01,
	92	+ 0x81, 0x02, 0x95, 0x01, 0x75, 0x05, 0x81, 0x01,
	93	+ 0x05, 0x01, 0x09, 0x30, 0x09, 0x31, 0x09, 0x38,
	94	+ 0x15, 0x80, 0x25, 0x7f, 0x75, 0x08, 0x95, 0x03,
	95	+ 0x81, 0x06, 0xc0, 0xc0,
	96	+};
	97	+
	98	+static int uhid_write(int fd, const struct uhid_event *ev)
	99	+{
	100	+ ssize_t ret;
	101	+
	102	+ ret = write(fd, ev, sizeof(*ev));
	103	+ if (ret < 0) {
	104	+ fprintf(stderr, "Cannot write to uhid: %m\n");
	105	+ return -errno;
	106	+ } else if (ret != sizeof(*ev)) {
	107	+ fprintf(stderr, "Wrong size written to uhid: %ld != %lu\n",
	108	+ ret, sizeof(ev));
	109	+ return -EFAULT;
	110	+ } else {
	111	+ return 0;
	112	+ }
	113	+}
	114	+
	115	+static int create(int fd)
	116	+{
	117	+ struct uhid_event ev;
	118	+
	119	+ memset(&ev, 0, sizeof(ev));
	120	+ ev.type = UHID_CREATE;
	121	+ strcpy((char*)ev.u.create.name, "test-uhid-device");
	122	+ ev.u.create.rd_data = rdesc;
	123	+ ev.u.create.rd_size = sizeof(rdesc);
	124	+ ev.u.create.bus = BUS_USB;
	125	+ ev.u.create.vendor = 0x15d9;
	126	+ ev.u.create.product = 0x0a37;
	127	+ ev.u.create.version = 0;
	128	+ ev.u.create.country = 0;
	129	+
	130	+ return uhid_write(fd, &ev);
	131	+}
	132	+
	133	+static void destroy(int fd)
	134	+{
	135	+ struct uhid_event ev;
	136	+
	137	+ memset(&ev, 0, sizeof(ev));
	138	+ ev.type = UHID_DESTROY;
	139	+
	140	+ uhid_write(fd, &ev);
	141	+}
	142	+
	143	+static int event(int fd)
	144	+{
	145	+ struct uhid_event ev;
	146	+ ssize_t ret;
	147	+
	148	+ memset(&ev, 0, sizeof(ev));
	149	+ ret = read(fd, &ev, sizeof(ev));
	150	+ if (ret == 0) {
	151	+ fprintf(stderr, "Read HUP on uhid-cdev\n");
	152	+ return -EFAULT;
	153	+ } else if (ret < 0) {
	154	+ fprintf(stderr, "Cannot read uhid-cdev: %m\n");
	155	+ return -errno;
	156	+ } else if (ret != sizeof(ev)) {
	157	+ fprintf(stderr, "Invalid size read from uhid-dev: %ld != %lu\n",
	158	+ ret, sizeof(ev));
	159	+ return -EFAULT;
	160	+ }
	161	+
	162	+ switch (ev.type) {
	163	+ case UHID_START:
	164	+ fprintf(stderr, "UHID_START from uhid-dev\n");
	165	+ break;
	166	+ case UHID_STOP:
	167	+ fprintf(stderr, "UHID_STOP from uhid-dev\n");
	168	+ break;
	169	+ case UHID_OPEN:
	170	+ fprintf(stderr, "UHID_OPEN from uhid-dev\n");
	171	+ break;
	172	+ case UHID_CLOSE:
	173	+ fprintf(stderr, "UHID_CLOSE from uhid-dev\n");
	174	+ break;
	175	+ case UHID_OUTPUT:
	176	+ fprintf(stderr, "UHID_OUTPUT from uhid-dev\n");
	177	+ break;
	178	+ case UHID_OUTPUT_EV:
	179	+ fprintf(stderr, "UHID_OUTPUT_EV from uhid-dev\n");
	180	+ break;
	181	+ default:
	182	+ fprintf(stderr, "Invalid event from uhid-dev: %u\n", ev.type);
	183	+ }
	184	+
	185	+ return 0;
	186	+}
	187	+
	188	+static bool btn1_down;
	189	+static bool btn2_down;
	190	+static bool btn3_down;
	191	+static signed char abs_hor;
	192	+static signed char abs_ver;
	193	+static signed char wheel;
	194	+
	195	+static int send_event(int fd)
	196	+{
	197	+ struct uhid_event ev;
	198	+
	199	+ memset(&ev, 0, sizeof(ev));
	200	+ ev.type = UHID_INPUT;
	201	+ ev.u.input.size = 4;
	202	+
	203	+ if (btn1_down)
	204	+ ev.u.input.data[0] \|= 0x1;
	205	+ if (btn2_down)
	206	+ ev.u.input.data[0] \|= 0x2;
	207	+ if (btn3_down)
	208	+ ev.u.input.data[0] \|= 0x4;
	209	+
	210	+ ev.u.input.data[1] = abs_hor;
	211	+ ev.u.input.data[2] = abs_ver;
	212	+ ev.u.input.data[3] = wheel;
	213	+
	214	+ return uhid_write(fd, &ev);
	215	+}
	216	+
	217	+static int keyboard(int fd)
	218	+{
	219	+ char buf[128];
	220	+ ssize_t ret, i;
	221	+
	222	+ ret = read(STDIN_FILENO, buf, sizeof(buf));
	223	+ if (ret == 0) {
	224	+ fprintf(stderr, "Read HUP on stdin\n");
	225	+ return -EFAULT;
	226	+ } else if (ret < 0) {
	227	+ fprintf(stderr, "Cannot read stdin: %m\n");
	228	+ return -errno;
	229	+ }
	230	+
	231	+ for (i = 0; i < ret; ++i) {
	232	+ switch (buf[i]) {
	233	+ case '1':
	234	+ btn1_down = !btn1_down;
	235	+ ret = send_event(fd);
	236	+ if (ret)
	237	+ return ret;
	238	+ break;
	239	+ case '2':
	240	+ btn2_down = !btn2_down;
	241	+ ret = send_event(fd);
	242	+ if (ret)
	243	+ return ret;
	244	+ break;
	245	+ case '3':
	246	+ btn3_down = !btn3_down;
	247	+ ret = send_event(fd);
	248	+ if (ret)
	249	+ return ret;
	250	+ break;
	251	+ case 'a':
	252	+ abs_hor = -20;
	253	+ ret = send_event(fd);
	254	+ abs_hor = 0;
	255	+ if (ret)
	256	+ return ret;
	257	+ break;
	258	+ case 'd':
	259	+ abs_hor = 20;
	260	+ ret = send_event(fd);
	261	+ abs_hor = 0;
	262	+ if (ret)
	263	+ return ret;
	264	+ break;
	265	+ case 'w':
	266	+ abs_ver = -20;
	267	+ ret = send_event(fd);
	268	+ abs_ver = 0;
	269	+ if (ret)
	270	+ return ret;
	271	+ break;
	272	+ case 's':
	273	+ abs_ver = 20;
	274	+ ret = send_event(fd);
	275	+ abs_ver = 0;
	276	+ if (ret)
	277	+ return ret;
	278	+ break;
	279	+ case 'r':
	280	+ wheel = 1;
	281	+ ret = send_event(fd);
	282	+ wheel = 0;
	283	+ if (ret)
	284	+ return ret;
	285	+ break;
	286	+ case 'f':
	287	+ wheel = -1;
	288	+ ret = send_event(fd);
	289	+ wheel = 0;
	290	+ if (ret)
	291	+ return ret;
	292	+ break;
	293	+ case 'q':
	294	+ return -ECANCELED;
	295	+ default:
	296	+ fprintf(stderr, "Invalid input: %c\n", buf[i]);
	297	+ }
	298	+ }
	299	+
	300	+ return 0;
	301	+}
	302	+
	303	+int main(int argc, char **argv)
	304	+{
	305	+ int fd;
	306	+ const char *path = "/dev/uhid";
	307	+ struct pollfd pfds[2];
	308	+ int ret;
	309	+ struct termios state;
	310	+
	311	+ ret = tcgetattr(STDIN_FILENO, &state);
	312	+ if (ret) {
	313	+ fprintf(stderr, "Cannot get tty state\n");
	314	+ } else {
	315	+ state.c_lflag &= ~ICANON;
	316	+ state.c_cc[VMIN] = 1;
	317	+ ret = tcsetattr(STDIN_FILENO, TCSANOW, &state);
	318	+ if (ret)
	319	+ fprintf(stderr, "Cannot set tty state\n");
	320	+ }
	321	+
	322	+ if (argc >= 2) {
	323	+ if (!strcmp(argv[1], "-h") \|\| !strcmp(argv[1], "--help")) {
	324	+ fprintf(stderr, "Usage: %s [%s]\n", argv[0], path);
	325	+ return EXIT_SUCCESS;
	326	+ } else {
	327	+ path = argv[1];
	328	+ }
	329	+ }
	330	+
	331	+ fprintf(stderr, "Open uhid-cdev %s\n", path);
	332	+ fd = open(path, O_RDWR \| O_CLOEXEC);
	333	+ if (fd < 0) {
	334	+ fprintf(stderr, "Cannot open uhid-cdev %s: %m\n", path);
	335	+ return EXIT_FAILURE;
	336	+ }
	337	+
	338	+ fprintf(stderr, "Create uhid device\n");
	339	+ ret = create(fd);
	340	+ if (ret) {
	341	+ close(fd);
	342	+ return EXIT_FAILURE;
	343	+ }
	344	+
	345	+ pfds[0].fd = STDIN_FILENO;
	346	+ pfds[0].events = POLLIN;
	347	+ pfds[1].fd = fd;
	348	+ pfds[1].events = POLLIN;
	349	+
	350	+ fprintf(stderr, "Press 'q' to quit...\n");
	351	+ while (1) {
	352	+ ret = poll(pfds, 2, -1);
	353	+ if (ret < 0) {
	354	+ fprintf(stderr, "Cannot poll for fds: %m\n");
	355	+ break;
	356	+ }
	357	+ if (pfds[0].revents & POLLHUP) {
	358	+ fprintf(stderr, "Received HUP on stdin\n");
	359	+ break;
	360	+ }
	361	+ if (pfds[1].revents & POLLHUP) {
	362	+ fprintf(stderr, "Received HUP on uhid-cdev\n");
	363	+ break;
	364	+ }
	365	+
	366	+ if (pfds[0].revents & POLLIN) {
	367	+ ret = keyboard(fd);
	368	+ if (ret)
	369	+ break;
	370	+ }
	371	+ if (pfds[1].revents & POLLIN) {
	372	+ ret = event(fd);
	373	+ if (ret)
	374	+ break;
	375	+ }
	376	+ }
	377	+
	378	+ fprintf(stderr, "Destroy uhid device\n");
	379	+ destroy(fd);
	380	+ return EXIT_SUCCESS;
	381	+}