linux/drivers/gpu/drm/nouveau/nvif/timer.c

/*
 * Copyright 2020 Red Hat Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */
#include <nvif/timer.h>
#include <nvif/device.h>

s64
nvif_timer_wait_test(struct nvif_timer_wait *wait)
{
	u64 time = nvif_device_time(wait->device);

	if (wait->reads == 0) {
		wait->time0 = time;
		wait->time1 = time;
	}

	if (wait->time1 == time) {
		if (WARN_ON(wait->reads++ == 16))
			return -ETIMEDOUT;
	} else {
		wait->time1 = time;
		wait->reads = 1;
	}

	if (wait->time1 - wait->time0 > wait->limit)
		return -ETIMEDOUT;

	return wait->time1 - wait->time0;
}

void
nvif_timer_wait_init(struct nvif_device *device, u64 nsec,
		     struct nvif_timer_wait *wait)
{
	wait->device = device;
	wait->limit = nsec;
	wait->reads = 0;
}