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>
This commit is contained in:
David Herrmann
Jiri Kosina
parent
58c59bc997
commit
f5e4e7fdd5
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@ -1,14 +1,15 @@
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/*
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* UHID Example
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*
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* Copyright (c) 2012 David Herrmann <dh.herrmann@googlemail.com>
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* Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
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*
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* The code may be used by anyone for any purpose,
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* and can serve as a starting point for developing
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* applications using uhid.
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*/
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/* UHID Example
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/*
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* UHID Example
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* This example emulates a basic 3 buttons mouse with wheel over UHID. Run this
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* program as root and then use the following keys to control the mouse:
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* q: Quit the application
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@ -22,6 +23,11 @@
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* r: Move wheel up
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* f: Move wheel down
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*
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* Additionally to 3 button mouse, 3 keyboard LEDs are also supported (LED_NUML,
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* LED_CAPSL and LED_SCROLLL). The device doesn't generate any related keyboard
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* events, though. You need to manually write the EV_LED/LED_XY/1 activation
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* input event to the evdev device to see it being sent to this device.
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*
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* If uhid is not available as /dev/uhid, then you can pass a different path as
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* first argument.
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* If <linux/uhid.h> is not installed in /usr, then compile this with:
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@ -41,11 +47,12 @@
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#include <unistd.h>
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#include <linux/uhid.h>
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/* HID Report Desciptor
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* We emulate a basic 3 button mouse with wheel. This is the report-descriptor
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* as the kernel will parse it:
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/*
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* HID Report Desciptor
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* We emulate a basic 3 button mouse with wheel and 3 keyboard LEDs. This is
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* the report-descriptor as the kernel will parse it:
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*
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* INPUT[INPUT]
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* INPUT(1)[INPUT]
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* Field(0)
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* Physical(GenericDesktop.Pointer)
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* Application(GenericDesktop.Mouse)
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@ -72,6 +79,19 @@
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* Report Count(3)
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* Report Offset(8)
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* Flags( Variable Relative )
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* OUTPUT(2)[OUTPUT]
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* Field(0)
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* Application(GenericDesktop.Keyboard)
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* Usage(3)
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* LED.NumLock
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* LED.CapsLock
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* LED.ScrollLock
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* Logical Minimum(0)
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* Logical Maximum(1)
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* Report Size(1)
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* Report Count(3)
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* Report Offset(0)
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* Flags( Variable Absolute )
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*
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* This is the mapping that we expect:
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* Button.0001 ---> Key.LeftBtn
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@ -80,19 +100,59 @@
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* GenericDesktop.X ---> Relative.X
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* GenericDesktop.Y ---> Relative.Y
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* GenericDesktop.Wheel ---> Relative.Wheel
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* LED.NumLock ---> LED.NumLock
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* LED.CapsLock ---> LED.CapsLock
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* LED.ScrollLock ---> LED.ScrollLock
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*
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* This information can be verified by reading /sys/kernel/debug/hid/<dev>/rdesc
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* This file should print the same information as showed above.
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*/
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static unsigned char rdesc[] = {
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0x05, 0x01, 0x09, 0x02, 0xa1, 0x01, 0x09, 0x01,
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0xa1, 0x00, 0x05, 0x09, 0x19, 0x01, 0x29, 0x03,
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0x15, 0x00, 0x25, 0x01, 0x95, 0x03, 0x75, 0x01,
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0x81, 0x02, 0x95, 0x01, 0x75, 0x05, 0x81, 0x01,
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0x05, 0x01, 0x09, 0x30, 0x09, 0x31, 0x09, 0x38,
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0x15, 0x80, 0x25, 0x7f, 0x75, 0x08, 0x95, 0x03,
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0x81, 0x06, 0xc0, 0xc0,
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0x05, 0x01, /* USAGE_PAGE (Generic Desktop) */
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0x09, 0x02, /* USAGE (Mouse) */
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0xa1, 0x01, /* COLLECTION (Application) */
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0x09, 0x01, /* USAGE (Pointer) */
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0xa1, 0x00, /* COLLECTION (Physical) */
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0x85, 0x01, /* REPORT_ID (1) */
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0x05, 0x09, /* USAGE_PAGE (Button) */
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0x19, 0x01, /* USAGE_MINIMUM (Button 1) */
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0x29, 0x03, /* USAGE_MAXIMUM (Button 3) */
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0x15, 0x00, /* LOGICAL_MINIMUM (0) */
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0x25, 0x01, /* LOGICAL_MAXIMUM (1) */
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0x95, 0x03, /* REPORT_COUNT (3) */
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0x75, 0x01, /* REPORT_SIZE (1) */
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0x81, 0x02, /* INPUT (Data,Var,Abs) */
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0x95, 0x01, /* REPORT_COUNT (1) */
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0x75, 0x05, /* REPORT_SIZE (5) */
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0x81, 0x01, /* INPUT (Cnst,Var,Abs) */
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0x05, 0x01, /* USAGE_PAGE (Generic Desktop) */
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0x09, 0x30, /* USAGE (X) */
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0x09, 0x31, /* USAGE (Y) */
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0x09, 0x38, /* USAGE (WHEEL) */
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0x15, 0x81, /* LOGICAL_MINIMUM (-127) */
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0x25, 0x7f, /* LOGICAL_MAXIMUM (127) */
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0x75, 0x08, /* REPORT_SIZE (8) */
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0x95, 0x03, /* REPORT_COUNT (3) */
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0x81, 0x06, /* INPUT (Data,Var,Rel) */
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0xc0, /* END_COLLECTION */
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0xc0, /* END_COLLECTION */
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0x05, 0x01, /* USAGE_PAGE (Generic Desktop) */
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0x09, 0x06, /* USAGE (Keyboard) */
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0xa1, 0x01, /* COLLECTION (Application) */
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0x85, 0x02, /* REPORT_ID (2) */
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0x05, 0x08, /* USAGE_PAGE (Led) */
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0x19, 0x01, /* USAGE_MINIMUM (1) */
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0x29, 0x03, /* USAGE_MAXIMUM (3) */
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0x15, 0x00, /* LOGICAL_MINIMUM (0) */
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0x25, 0x01, /* LOGICAL_MAXIMUM (1) */
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0x95, 0x03, /* REPORT_COUNT (3) */
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0x75, 0x01, /* REPORT_SIZE (1) */
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0x91, 0x02, /* Output (Data,Var,Abs) */
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0x95, 0x01, /* REPORT_COUNT (1) */
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0x75, 0x05, /* REPORT_SIZE (5) */
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0x91, 0x01, /* Output (Cnst,Var,Abs) */
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0xc0, /* END_COLLECTION */
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};
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static int uhid_write(int fd, const struct uhid_event *ev)
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@ -140,6 +200,27 @@ static void destroy(int fd)
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uhid_write(fd, &ev);
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}
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/* This parses raw output reports sent by the kernel to the device. A normal
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* uhid program shouldn't do this but instead just forward the raw report.
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* However, for ducomentational purposes, we try to detect LED events here and
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* print debug messages for it. */
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static void handle_output(struct uhid_event *ev)
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{
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/* LED messages are adverised via OUTPUT reports; ignore the rest */
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if (ev->u.output.rtype != UHID_OUTPUT_REPORT)
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return;
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/* LED reports have length 2 bytes */
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if (ev->u.output.size != 2)
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return;
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/* first byte is report-id which is 0x02 for LEDs in our rdesc */
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if (ev->u.output.data[0] != 0x2)
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return;
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/* print flags payload */
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fprintf(stderr, "LED output report received with flags %x\n",
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ev->u.output.data[1]);
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}
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static int event(int fd)
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{
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struct uhid_event ev;
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@ -174,6 +255,7 @@ static int event(int fd)
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break;
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case UHID_OUTPUT:
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fprintf(stderr, "UHID_OUTPUT from uhid-dev\n");
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handle_output(&ev);
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break;
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case UHID_OUTPUT_EV:
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fprintf(stderr, "UHID_OUTPUT_EV from uhid-dev\n");
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@ -198,18 +280,19 @@ static int send_event(int fd)
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memset(&ev, 0, sizeof(ev));
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ev.type = UHID_INPUT;
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ev.u.input.size = 4;
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ev.u.input.size = 5;
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ev.u.input.data[0] = 0x1;
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if (btn1_down)
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ev.u.input.data[0] |= 0x1;
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ev.u.input.data[1] |= 0x1;
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if (btn2_down)
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ev.u.input.data[0] |= 0x2;
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ev.u.input.data[1] |= 0x2;
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if (btn3_down)
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ev.u.input.data[0] |= 0x4;
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ev.u.input.data[1] |= 0x4;
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ev.u.input.data[1] = abs_hor;
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ev.u.input.data[2] = abs_ver;
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ev.u.input.data[3] = wheel;
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ev.u.input.data[2] = abs_hor;
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ev.u.input.data[3] = abs_ver;
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ev.u.input.data[4] = wheel;
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return uhid_write(fd, &ev);
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}
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