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![Dean Camera](/assets/img/avatar_default.png)
Currently the hidraw module can only read and write feature HID reports on demand, via dedicated ioctls. Input reports are read from the device through the read() interface, while output reports are written through the write interface(). This is insufficient; it is desirable in many situations to be able to read and write input and output reports through the control interface to cover additional scenarios: - Reading an input report by its report ID, to get initial state - Writing an input report, to set initial input state in the device - Reading an output report by its report ID, to obtain current state - Writing an output report by its report ID, out of band This patch adds these missing ioctl requests to read and write the remaining HID report types. Note that not all HID backends will neccesarily support this (e.g. while the USB link layer supports setting Input reports, others may not). Also included are documentation and example updates. The current hidraw documentation states that feature reports read from the device does *not* include the report ID, however this is not the case and the returned report will have its report ID prepended by conforming HID devices, as the report data sent from the device over the control endpoint must be indentical in format to those sent over the regular transport. Signed-off-by: Dean Camera <dean@fourwalledcubicle.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
182 lines
3.9 KiB
C
182 lines
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Hidraw Userspace Example
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*
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* Copyright (c) 2010 Alan Ott <alan@signal11.us>
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* Copyright (c) 2010 Signal 11 Software
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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 hidraw.
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*/
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/* Linux */
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#include <linux/types.h>
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#include <linux/input.h>
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#include <linux/hidraw.h>
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/*
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* Ugly hack to work around failing compilation on systems that don't
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* yet populate new version of hidraw.h to userspace.
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*/
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#ifndef HIDIOCSFEATURE
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#warning Please have your distro update the userspace kernel headers
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#define HIDIOCSFEATURE(len) _IOC(_IOC_WRITE|_IOC_READ, 'H', 0x06, len)
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#define HIDIOCGFEATURE(len) _IOC(_IOC_WRITE|_IOC_READ, 'H', 0x07, len)
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#endif
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/* Unix */
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#include <sys/ioctl.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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/* C */
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <errno.h>
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const char *bus_str(int bus);
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int main(int argc, char **argv)
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{
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int fd;
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int i, res, desc_size = 0;
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char buf[256];
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struct hidraw_report_descriptor rpt_desc;
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struct hidraw_devinfo info;
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char *device = "/dev/hidraw0";
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if (argc > 1)
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device = argv[1];
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/* Open the Device with non-blocking reads. In real life,
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don't use a hard coded path; use libudev instead. */
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fd = open(device, O_RDWR|O_NONBLOCK);
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if (fd < 0) {
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perror("Unable to open device");
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return 1;
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}
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memset(&rpt_desc, 0x0, sizeof(rpt_desc));
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memset(&info, 0x0, sizeof(info));
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memset(buf, 0x0, sizeof(buf));
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/* Get Report Descriptor Size */
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res = ioctl(fd, HIDIOCGRDESCSIZE, &desc_size);
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if (res < 0)
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perror("HIDIOCGRDESCSIZE");
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else
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printf("Report Descriptor Size: %d\n", desc_size);
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/* Get Report Descriptor */
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rpt_desc.size = desc_size;
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res = ioctl(fd, HIDIOCGRDESC, &rpt_desc);
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if (res < 0) {
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perror("HIDIOCGRDESC");
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} else {
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printf("Report Descriptor:\n");
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for (i = 0; i < rpt_desc.size; i++)
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printf("%hhx ", rpt_desc.value[i]);
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puts("\n");
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}
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/* Get Raw Name */
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res = ioctl(fd, HIDIOCGRAWNAME(256), buf);
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if (res < 0)
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perror("HIDIOCGRAWNAME");
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else
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printf("Raw Name: %s\n", buf);
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/* Get Physical Location */
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res = ioctl(fd, HIDIOCGRAWPHYS(256), buf);
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if (res < 0)
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perror("HIDIOCGRAWPHYS");
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else
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printf("Raw Phys: %s\n", buf);
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/* Get Raw Info */
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res = ioctl(fd, HIDIOCGRAWINFO, &info);
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if (res < 0) {
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perror("HIDIOCGRAWINFO");
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} else {
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printf("Raw Info:\n");
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printf("\tbustype: %d (%s)\n",
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info.bustype, bus_str(info.bustype));
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printf("\tvendor: 0x%04hx\n", info.vendor);
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printf("\tproduct: 0x%04hx\n", info.product);
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}
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/* Set Feature */
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buf[0] = 0x9; /* Report Number */
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buf[1] = 0xff;
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buf[2] = 0xff;
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buf[3] = 0xff;
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res = ioctl(fd, HIDIOCSFEATURE(4), buf);
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if (res < 0)
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perror("HIDIOCSFEATURE");
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else
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printf("ioctl HIDIOCSFEATURE returned: %d\n", res);
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/* Get Feature */
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buf[0] = 0x9; /* Report Number */
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res = ioctl(fd, HIDIOCGFEATURE(256), buf);
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if (res < 0) {
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perror("HIDIOCGFEATURE");
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} else {
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printf("ioctl HIDIOCGFEATURE returned: %d\n", res);
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printf("Report data:\n\t");
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for (i = 0; i < res; i++)
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printf("%hhx ", buf[i]);
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puts("\n");
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}
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/* Send a Report to the Device */
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buf[0] = 0x1; /* Report Number */
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buf[1] = 0x77;
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res = write(fd, buf, 2);
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if (res < 0) {
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printf("Error: %d\n", errno);
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perror("write");
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} else {
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printf("write() wrote %d bytes\n", res);
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}
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/* Get a report from the device */
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res = read(fd, buf, 16);
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if (res < 0) {
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perror("read");
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} else {
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printf("read() read %d bytes:\n\t", res);
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for (i = 0; i < res; i++)
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printf("%hhx ", buf[i]);
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puts("\n");
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}
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close(fd);
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return 0;
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}
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const char *
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bus_str(int bus)
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{
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switch (bus) {
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case BUS_USB:
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return "USB";
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break;
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case BUS_HIL:
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return "HIL";
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break;
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case BUS_BLUETOOTH:
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return "Bluetooth";
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break;
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case BUS_VIRTUAL:
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return "Virtual";
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break;
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default:
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return "Other";
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break;
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}
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}
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