monado/src/xrt/auxiliary/os/os_hid_hidraw.c

// Copyright 2019, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief  Hid implementation based on hidraw.
 * @author Jakob Bornecrantz <jakob@collabora.com>
 * @ingroup aux_os
 */

#include "os_hid.h"

#ifdef XRT_OS_LINUX

#include "util/u_misc.h"
#include <poll.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>

#include <sys/ioctl.h>

#include <linux/hidraw.h>


#include <stdio.h>

struct hid_hidraw
{
	struct os_hid_device base;

	int fd;
};

static int
os_hidraw_read(struct os_hid_device *ohdev,
               uint8_t *data,
               size_t length,
               int milliseconds)
{
	struct hid_hidraw *hrdev = (struct hid_hidraw *)ohdev;
	struct pollfd fds;
	int ret;

	if (milliseconds >= 0) {
		fds.fd = hrdev->fd;
		fds.events = POLLIN;
		fds.revents = 0;
		ret = poll(&fds, 1, milliseconds);

		if (ret == -1 || ret == 0) {
			// Error or timeout.
			return ret;
		} else if (fds.revents & (POLLERR | POLLHUP | POLLNVAL)) {
			// Device disconnect?
			return -1;
		}
	}

	ret = read(hrdev->fd, data, length);

	if (ret < 0 && (errno == EAGAIN || errno == EINPROGRESS)) {
		// Process most likely received a signal.
		ret = 0;
	}

	return ret;
}

static int
os_hidraw_write(struct os_hid_device *ohdev, const uint8_t *data, size_t length)
{
	struct hid_hidraw *hrdev = (struct hid_hidraw *)ohdev;

	return write(hrdev->fd, data, length);
}

static void
os_hidraw_destroy(struct os_hid_device *ohdev)
{
	struct hid_hidraw *hrdev = (struct hid_hidraw *)ohdev;

	close(hrdev->fd);
	free(hrdev);
}

int
os_hid_open_hidraw(const char *path, struct os_hid_device **out_ohdev)
{
	struct hid_hidraw *hrdev = U_TYPED_CALLOC(struct hid_hidraw);

	hrdev->base.read = os_hidraw_read;
	hrdev->base.write = os_hidraw_write;
	hrdev->base.destroy = os_hidraw_destroy;
	hrdev->fd = open(path, O_RDWR);
	if (hrdev->fd < 0) {
		free(hrdev);
		return -1;
	}

	*out_ohdev = &hrdev->base;

	return 0;
}

#endif