HID: Documentation for hidraw
Documenation for the hidraw driver, with sample program. Signed-off-by: Alan Ott <alan@signal11.us> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit is contained in:
Alan Ott
Jiri Kosina
Родитель
99759619b2
Коммит
c54ea4918c
|
|
@ -0,0 +1,119 @@
|
|||
HIDRAW - Raw Access to USB and Bluetooth Human Interface Devices
|
||||
==================================================================
|
||||
|
||||
The hidraw driver provides a raw interface to USB and Bluetooth Human
|
||||
Interface Devices (HIDs). It differs from hiddev in that reports sent and
|
||||
received are not parsed by the HID parser, but are sent to and received from
|
||||
the device unmodified.
|
||||
|
||||
Hidraw should be used if the userspace application knows exactly how to
|
||||
communicate with the hardware device, and is able to construct the HID
|
||||
reports manually. This is often the case when making userspace drivers for
|
||||
custom HID devices.
|
||||
|
||||
Hidraw is also useful for communicating with non-conformant HID devices
|
||||
which send and receive data in a way that is inconsistent with their report
|
||||
descriptors. Because hiddev parses reports which are sent and received
|
||||
through it, checking them against the device's report descriptor, such
|
||||
communication with these non-conformant devices is impossible using hiddev.
|
||||
Hidraw is the only alternative, short of writing a custom kernel driver, for
|
||||
these non-conformant devices.
|
||||
|
||||
A benefit of hidraw is that its use by userspace applications is independent
|
||||
of the underlying hardware type. Currently, Hidraw is implemented for USB
|
||||
and Bluetooth. In the future, as new hardware bus types are developed which
|
||||
use the HID specification, hidraw will be expanded to add support for these
|
||||
new bus types.
|
||||
|
||||
Hidraw uses a dynamic major number, meaning that udev should be relied on to
|
||||
create hidraw device nodes. Udev will typically create the device nodes
|
||||
directly under /dev (eg: /dev/hidraw0). As this location is distribution-
|
||||
and udev rule-dependent, applications should use libudev to locate hidraw
|
||||
devices attached to the system. There is a tutorial on libudev with a
|
||||
working example at:
|
||||
http://www.signal11.us/oss/udev/
|
||||
|
||||
The HIDRAW API
|
||||
---------------
|
||||
|
||||
read()
|
||||
-------
|
||||
read() will read a queued report received from the HID device. On USB
|
||||
devices, the reports read using read() are the reports sent from the device
|
||||
on the INTERRUPT IN endpoint. By default, read() will block until there is
|
||||
a report available to be read. read() can be made non-blocking, by passing
|
||||
the O_NONBLOCK flag to open(), or by setting the O_NONBLOCK flag using
|
||||
fcntl().
|
||||
|
||||
On a device which uses numbered reports, the first byte of the returned data
|
||||
will be the report number; the report data follows, beginning in the second
|
||||
byte. For devices which do not use numbered reports, the report data
|
||||
will begin at the first byte.
|
||||
|
||||
write()
|
||||
--------
|
||||
The write() function will write a report to the device. For USB devices, if
|
||||
the device has an INTERRUPT OUT endpoint, the report will be sent on that
|
||||
endpoint. If it does not, the report will be sent over the control endpoint,
|
||||
using a SET_REPORT transfer.
|
||||
|
||||
The first byte of the buffer passed to write() should be set to the report
|
||||
number. If the device does not use numbered reports, the first byte should
|
||||
be set to 0. The report data itself should begin at the second byte.
|
||||
|
||||
ioctl()
|
||||
--------
|
||||
Hidraw supports the following ioctls:
|
||||
|
||||
HIDIOCGRDESCSIZE: Get Report Descriptor Size
|
||||
This ioctl will get the size of the device's report descriptor.
|
||||
|
||||
HIDIOCGRDESC: Get Report Descriptor
|
||||
This ioctl returns the device's report descriptor using a
|
||||
hidraw_report_descriptor struct. Make sure to set the size field of the
|
||||
hidraw_report_descriptor struct to the size returned from HIDIOCGRDESCSIZE.
|
||||
|
||||
HIDIOCGRAWINFO: Get Raw Info
|
||||
This ioctl will return a hidraw_devinfo struct containing the bus type, the
|
||||
vendor ID (VID), and product ID (PID) of the device. The bus type can be one
|
||||
of:
|
||||
BUS_USB
|
||||
BUS_HIL
|
||||
BUS_BLUETOOTH
|
||||
BUS_VIRTUAL
|
||||
which are defined in linux/input.h.
|
||||
|
||||
HIDIOCGRAWNAME(len): Get Raw Name
|
||||
This ioctl returns a string containing the vendor and product strings of
|
||||
the device. The returned string is Unicode, UTF-8 encoded.
|
||||
|
||||
HIDIOCGRAWPHYS(len): Get Physical Address
|
||||
This ioctl returns a string representing the physical address of the device.
|
||||
For USB devices, the string contains the physical path to the device (the
|
||||
USB controller, hubs, ports, etc). For Bluetooth devices, the string
|
||||
contains the hardware (MAC) address of the device.
|
||||
|
||||
HIDIOCSFEATURE(len): Send a Feature Report
|
||||
This ioctl will send a feature report to the device. Per the HID
|
||||
specification, feature reports are always sent using the control endpoint.
|
||||
Set the first byte of the supplied buffer to the report number. For devices
|
||||
which do not use numbered reports, set the first byte to 0. The report data
|
||||
begins in the second byte. Make sure to set len accordingly, to one more
|
||||
than the length of the report (to account for the report number).
|
||||
|
||||
HIDIOCGFEATURE(len): Get a Feature Report
|
||||
This ioctl will request a feature report from the device using the control
|
||||
endpoint. The first byte of the supplied buffer should be set to the report
|
||||
number of the requested report. For devices which do not use numbered
|
||||
reports, set the first byte to 0. The report will be returned starting at
|
||||
the first byte of the buffer (ie: the report number is not returned).
|
||||
|
||||
Example
|
||||
---------
|
||||
In samples/, find hid-example.c, which shows examples of read(), write(),
|
||||
and all the ioctls for hidraw. The code may be used by anyone for any
|
||||
purpose, and can serve as a starting point for developing applications using
|
||||
hidraw.
|
||||
|
||||
Document by:
|
||||
Alan Ott <alan@signal11.us>, Signal 11 Software
|
||||
|
|
@ -61,4 +61,10 @@ config SAMPLE_KDB
|
|||
Build an example of how to dynamically add the hello
|
||||
command to the kdb shell.
|
||||
|
||||
config SAMPLE_HIDRAW
|
||||
tristate "Build simple hidraw example"
|
||||
depends on HIDRAW
|
||||
help
|
||||
Build an example of how to use hidraw from userspace.
|
||||
|
||||
endif # SAMPLES
|
||||
|
|
|
|||
|
|
@ -1,4 +1,4 @@
|
|||
# Makefile for Linux samples code
|
||||
|
||||
obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ tracepoints/ trace_events/ \
|
||||
hw_breakpoint/ kfifo/ kdb/
|
||||
hw_breakpoint/ kfifo/ kdb/ hidraw/
|
||||
|
|
|
|||
|
|
@ -0,0 +1,8 @@
|
|||
# kbuild trick to avoid linker error. Can be omitted if a module is built.
|
||||
obj- := dummy.o
|
||||
|
||||
# List of programs to build
|
||||
hostprogs-y := hid-example
|
||||
|
||||
# Tell kbuild to always build the programs
|
||||
always := $(hostprogs-y)
|
||||
|
|
@ -0,0 +1,167 @@
|
|||
/*
|
||||
* Hidraw Userspace Example
|
||||
*
|
||||
* Copyright (c) 2010 Alan Ott <alan@signal11.us>
|
||||
* Copyright (c) 2010 Signal 11 Software
|
||||
*
|
||||
* The code may be used by anyone for any purpose,
|
||||
* and can serve as a starting point for developing
|
||||
* applications using hidraw.
|
||||
*/
|
||||
|
||||
/* Linux */
|
||||
#include <linux/types.h>
|
||||
#include <linux/input.h>
|
||||
#include <linux/hidraw.h>
|
||||
|
||||
/* Unix */
|
||||
#include <sys/ioctl.h>
|
||||
#include <sys/types.h>
|
||||
#include <sys/stat.h>
|
||||
#include <fcntl.h>
|
||||
#include <unistd.h>
|
||||
|
||||
/* C */
|
||||
#include <stdio.h>
|
||||
#include <string.h>
|
||||
#include <stdlib.h>
|
||||
#include <errno.h>
|
||||
|
||||
const char *bus_str(int bus);
|
||||
|
||||
int main(int argc, char **argv)
|
||||
{
|
||||
int fd;
|
||||
int i, res, desc_size = 0;
|
||||
char buf[256];
|
||||
struct hidraw_report_descriptor rpt_desc;
|
||||
struct hidraw_devinfo info;
|
||||
|
||||
/* Open the Device with non-blocking reads. In real life,
|
||||
don't use a hard coded path; use libudev instead. */
|
||||
fd = open("/dev/hidraw0", O_RDWR|O_NONBLOCK);
|
||||
|
||||
if (fd < 0) {
|
||||
perror("Unable to open device");
|
||||
return 1;
|
||||
}
|
||||
|
||||
memset(&rpt_desc, 0x0, sizeof(rpt_desc));
|
||||
memset(&info, 0x0, sizeof(info));
|
||||
memset(buf, 0x0, sizeof(buf));
|
||||
|
||||
/* Get Report Descriptor Size */
|
||||
res = ioctl(fd, HIDIOCGRDESCSIZE, &desc_size);
|
||||
if (res < 0)
|
||||
perror("HIDIOCGRDESCSIZE");
|
||||
else
|
||||
printf("Report Descriptor Size: %d\n", desc_size);
|
||||
|
||||
/* Get Report Descriptor */
|
||||
rpt_desc.size = desc_size;
|
||||
res = ioctl(fd, HIDIOCGRDESC, &rpt_desc);
|
||||
if (res < 0) {
|
||||
perror("HIDIOCGRDESC");
|
||||
} else {
|
||||
printf("Report Descriptor:\n");
|
||||
for (i = 0; i < rpt_desc.size; i++)
|
||||
printf("%hhx ", rpt_desc.value[i]);
|
||||
puts("\n");
|
||||
}
|
||||
|
||||
/* Get Raw Name */
|
||||
res = ioctl(fd, HIDIOCGRAWNAME(256), buf);
|
||||
if (res < 0)
|
||||
perror("HIDIOCGRAWNAME");
|
||||
else
|
||||
printf("Raw Name: %s\n", buf);
|
||||
|
||||
/* Get Physical Location */
|
||||
res = ioctl(fd, HIDIOCGRAWPHYS(256), buf);
|
||||
if (res < 0)
|
||||
perror("HIDIOCGRAWPHYS");
|
||||
else
|
||||
printf("Raw Phys: %s\n", buf);
|
||||
|
||||
/* Get Raw Info */
|
||||
res = ioctl(fd, HIDIOCGRAWINFO, &info);
|
||||
if (res < 0) {
|
||||
perror("HIDIOCGRAWINFO");
|
||||
} else {
|
||||
printf("Raw Info:\n");
|
||||
printf("\tbustype: %d (%s)\n",
|
||||
info.bustype, bus_str(info.bustype));
|
||||
printf("\tvendor: 0x%04hx\n", info.vendor);
|
||||
printf("\tproduct: 0x%04hx\n", info.product);
|
||||
}
|
||||
|
||||
/* Set Feature */
|
||||
buf[0] = 0x9; /* Report Number */
|
||||
buf[1] = 0xff;
|
||||
buf[2] = 0xff;
|
||||
buf[3] = 0xff;
|
||||
res = ioctl(fd, HIDIOCSFEATURE(4), buf);
|
||||
if (res < 0)
|
||||
perror("HIDIOCSFEATURE");
|
||||
else
|
||||
printf("ioctl HIDIOCGFEATURE returned: %d\n", res);
|
||||
|
||||
/* Get Feature */
|
||||
buf[0] = 0x9; /* Report Number */
|
||||
res = ioctl(fd, HIDIOCGFEATURE(256), buf);
|
||||
if (res < 0) {
|
||||
perror("HIDIOCGFEATURE");
|
||||
} else {
|
||||
printf("ioctl HIDIOCGFEATURE returned: %d\n", res);
|
||||
printf("Report data (not containing the report number):\n\t");
|
||||
for (i = 0; i < res; i++)
|
||||
printf("%hhx ", buf[i]);
|
||||
puts("\n");
|
||||
}
|
||||
|
||||
/* Send a Report to the Device */
|
||||
buf[0] = 0x1; /* Report Number */
|
||||
buf[1] = 0x77;
|
||||
res = write(fd, buf, 2);
|
||||
if (res < 0) {
|
||||
printf("Error: %d\n", errno);
|
||||
perror("write");
|
||||
} else {
|
||||
printf("write() wrote %d bytes\n", res);
|
||||
}
|
||||
|
||||
/* Get a report from the device */
|
||||
res = read(fd, buf, 16);
|
||||
if (res < 0) {
|
||||
perror("read");
|
||||
} else {
|
||||
printf("read() read %d bytes:\n\t", res);
|
||||
for (i = 0; i < res; i++)
|
||||
printf("%hhx ", buf[i]);
|
||||
puts("\n");
|
||||
}
|
||||
close(fd);
|
||||
return 0;
|
||||
}
|
||||
|
||||
const char *
|
||||
bus_str(int bus)
|
||||
{
|
||||
switch (bus) {
|
||||
case BUS_USB:
|
||||
return "USB";
|
||||
break;
|
||||
case BUS_HIL:
|
||||
return "HIL";
|
||||
break;
|
||||
case BUS_BLUETOOTH:
|
||||
return "Bluetooth";
|
||||
break;
|
||||
case BUS_VIRTUAL:
|
||||
return "Virtual";
|
||||
break;
|
||||
default:
|
||||
return "Other";
|
||||
break;
|
||||
}
|
||||
}
|
||||
Загрузка…
Ссылка в новой задаче