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Commit f5e4e7fd authored by David Herrmann's avatar David Herrmann Committed by Jiri Kosina
Browse files

HID: uhid: improve uhid example client 



This extends the uhid example client. It properly documents the built-in
report-descriptor an adds explicit report-numbers.

Furthermore, LED output reports are added to utilize the new UHID output
reports of the kernel. Support for 3 basic LEDs is added and a small
report-parser to print debug messages if output reports were received.

To test this, simply write the EV_LED+LED_CAPSL+1 event to the evdev
device-node of the uhid-device and the kernel will forward it to your uhid
client.

Signed-off-by: default avatarDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 58c59bc9

samples/uhid/uhid-example.c

+103 −20
Original line number Diff line number Diff line 
/*

 * UHID Example

 *

 * Copyright (c) 2012 David Herrmann <dh.herrmann@googlemail.com>

 * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.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

/*

 * 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
@@ -22,6 +23,11 @@ 
 *   r: Move wheel up

 *   f: Move wheel down

 *

 * Additionally to 3 button mouse, 3 keyboard LEDs are also supported (LED_NUML,

 * LED_CAPSL and LED_SCROLLL). The device doesn't generate any related keyboard

 * events, though. You need to manually write the EV_LED/LED_XY/1 activation

 * input event to the evdev device to see it being sent to this device.

 *

 * 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:
@@ -41,11 +47,12 @@ 
#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:

/*

 * HID Report Desciptor

 * We emulate a basic 3 button mouse with wheel and 3 keyboard LEDs. This is

 * the report-descriptor as the kernel will parse it:

 *

 * INPUT[INPUT]

 * INPUT(1)[INPUT]

 *   Field(0)

 *     Physical(GenericDesktop.Pointer)

 *     Application(GenericDesktop.Mouse)
@@ -72,6 +79,19 @@ 
 *     Report Count(3)

 *     Report Offset(8)

 *     Flags( Variable Relative )

 * OUTPUT(2)[OUTPUT]

 *   Field(0)

 *     Application(GenericDesktop.Keyboard)

 *     Usage(3)

 *       LED.NumLock

 *       LED.CapsLock

 *       LED.ScrollLock

 *     Logical Minimum(0)

 *     Logical Maximum(1)

 *     Report Size(1)

 *     Report Count(3)

 *     Report Offset(0)

 *     Flags( Variable Absolute )

 *

 * This is the mapping that we expect:

 *   Button.0001 ---> Key.LeftBtn
@@ -80,19 +100,59 @@ 
 *   GenericDesktop.X ---> Relative.X

 *   GenericDesktop.Y ---> Relative.Y

 *   GenericDesktop.Wheel ---> Relative.Wheel

 *   LED.NumLock ---> LED.NumLock

 *   LED.CapsLock ---> LED.CapsLock

 *   LED.ScrollLock ---> LED.ScrollLock

 *

 * 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,

	0x05, 0x01,	/* USAGE_PAGE (Generic Desktop) */

	0x09, 0x02,	/* USAGE (Mouse) */

	0xa1, 0x01,	/* COLLECTION (Application) */

	0x09, 0x01,		/* USAGE (Pointer) */

	0xa1, 0x00,		/* COLLECTION (Physical) */

	0x85, 0x01,			/* REPORT_ID (1) */

	0x05, 0x09,			/* USAGE_PAGE (Button) */

	0x19, 0x01,			/* USAGE_MINIMUM (Button 1) */

	0x29, 0x03,			/* USAGE_MAXIMUM (Button 3) */

	0x15, 0x00,			/* LOGICAL_MINIMUM (0) */

	0x25, 0x01,			/* LOGICAL_MAXIMUM (1) */

	0x95, 0x03,			/* REPORT_COUNT (3) */

	0x75, 0x01,			/* REPORT_SIZE (1) */

	0x81, 0x02,			/* INPUT (Data,Var,Abs) */

	0x95, 0x01,			/* REPORT_COUNT (1) */

	0x75, 0x05,			/* REPORT_SIZE (5) */

	0x81, 0x01,			/* INPUT (Cnst,Var,Abs) */

	0x05, 0x01,			/* USAGE_PAGE (Generic Desktop) */

	0x09, 0x30,			/* USAGE (X) */

	0x09, 0x31,			/* USAGE (Y) */

	0x09, 0x38,			/* USAGE (WHEEL) */

	0x15, 0x81,			/* LOGICAL_MINIMUM (-127) */

	0x25, 0x7f,			/* LOGICAL_MAXIMUM (127) */

	0x75, 0x08,			/* REPORT_SIZE (8) */

	0x95, 0x03,			/* REPORT_COUNT (3) */

	0x81, 0x06,			/* INPUT (Data,Var,Rel) */

	0xc0,			/* END_COLLECTION */

	0xc0,		/* END_COLLECTION */

	0x05, 0x01,	/* USAGE_PAGE (Generic Desktop) */

	0x09, 0x06,	/* USAGE (Keyboard) */

	0xa1, 0x01,	/* COLLECTION (Application) */

	0x85, 0x02,		/* REPORT_ID (2) */

	0x05, 0x08,		/* USAGE_PAGE (Led) */

	0x19, 0x01,		/* USAGE_MINIMUM (1) */

	0x29, 0x03,		/* USAGE_MAXIMUM (3) */

	0x15, 0x00,		/* LOGICAL_MINIMUM (0) */

	0x25, 0x01,		/* LOGICAL_MAXIMUM (1) */

	0x95, 0x03,		/* REPORT_COUNT (3) */

	0x75, 0x01,		/* REPORT_SIZE (1) */

	0x91, 0x02,		/* Output (Data,Var,Abs) */

	0x95, 0x01,		/* REPORT_COUNT (1) */

	0x75, 0x05,		/* REPORT_SIZE (5) */

	0x91, 0x01,		/* Output (Cnst,Var,Abs) */

	0xc0,		/* END_COLLECTION */

};



static int uhid_write(int fd, const struct uhid_event *ev)
@@ -140,6 +200,27 @@ static void destroy(int fd) 
	uhid_write(fd, &ev);

}



/* This parses raw output reports sent by the kernel to the device. A normal

 * uhid program shouldn't do this but instead just forward the raw report.

 * However, for ducomentational purposes, we try to detect LED events here and

 * print debug messages for it. */

static void handle_output(struct uhid_event *ev)

{

	/* LED messages are adverised via OUTPUT reports; ignore the rest */

	if (ev->u.output.rtype != UHID_OUTPUT_REPORT)

		return;

	/* LED reports have length 2 bytes */

	if (ev->u.output.size != 2)

		return;

	/* first byte is report-id which is 0x02 for LEDs in our rdesc */

	if (ev->u.output.data[0] != 0x2)

		return;



	/* print flags payload */

	fprintf(stderr, "LED output report received with flags %x\n",

		ev->u.output.data[1]);

}



static int event(int fd)

{

	struct uhid_event ev;
@@ -174,6 +255,7 @@ static int event(int fd) 
		break;

	case UHID_OUTPUT:

		fprintf(stderr, "UHID_OUTPUT from uhid-dev\n");

		handle_output(&ev);

		break;

	case UHID_OUTPUT_EV:

		fprintf(stderr, "UHID_OUTPUT_EV from uhid-dev\n");
@@ -198,18 +280,19 @@ static int send_event(int fd) 


	memset(&ev, 0, sizeof(ev));

	ev.type = UHID_INPUT;

	ev.u.input.size = 4;

	ev.u.input.size = 5;



	ev.u.input.data[0] = 0x1;

	if (btn1_down)

		ev.u.input.data[0] |= 0x1;

		ev.u.input.data[1] |= 0x1;

	if (btn2_down)

		ev.u.input.data[0] |= 0x2;

		ev.u.input.data[1] |= 0x2;

	if (btn3_down)

		ev.u.input.data[0] |= 0x4;

		ev.u.input.data[1] |= 0x4;



	ev.u.input.data[1] = abs_hor;

	ev.u.input.data[2] = abs_ver;

	ev.u.input.data[3] = wheel;

	ev.u.input.data[2] = abs_hor;

	ev.u.input.data[3] = abs_ver;

	ev.u.input.data[4] = wheel;



	return uhid_write(fd, &ev);

}