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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: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
master
David Herrmann 8 years ago
committed by Jiri Kosina
parent
commit
f5e4e7fdd5
  1. 123
      samples/uhid/uhid-example.c

123
samples/uhid/uhid-example.c

@ -1,14 +1,15 @@
/*
* 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);
}

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