linux/drivers/gpu/drm/panfrost/panfrost_devfreq.c

// SPDX-License-Identifier: GPL-2.0
/* Copyright 2019 Collabora ltd. */

#include <linux/clk.h>
#include <linux/devfreq.h>
#include <linux/devfreq_cooling.h>
#include <linux/platform_device.h>
#include <linux/pm_opp.h>

#include "panfrost_device.h"
#include "panfrost_devfreq.h"

static void panfrost_devfreq_update_utilization(struct panfrost_devfreq *pfdevfreq)
{
	ktime_t now;
	ktime_t last;

	if (!pfdevfreq->devfreq)
		return;

	now = ktime_get();
	last = pfdevfreq->time_last_update;

	if (atomic_read(&pfdevfreq->busy_count) > 0)
		pfdevfreq->busy_time += ktime_sub(now, last);
	else
		pfdevfreq->idle_time += ktime_sub(now, last);

	pfdevfreq->time_last_update = now;
}

static int panfrost_devfreq_target(struct device *dev, unsigned long *freq,
				   u32 flags)
{
	struct dev_pm_opp *opp;
	int err;

	opp = devfreq_recommended_opp(dev, freq, flags);
	if (IS_ERR(opp))
		return PTR_ERR(opp);
	dev_pm_opp_put(opp);

	err = dev_pm_opp_set_rate(dev, *freq);
	if (err)
		return err;

	return 0;
}

static void panfrost_devfreq_reset(struct panfrost_devfreq *pfdevfreq)
{
	pfdevfreq->busy_time = 0;
	pfdevfreq->idle_time = 0;
	pfdevfreq->time_last_update = ktime_get();
}

static int panfrost_devfreq_get_dev_status(struct device *dev,
					   struct devfreq_dev_status *status)
{
	struct panfrost_device *pfdev = dev_get_drvdata(dev);
	struct panfrost_devfreq *pfdevfreq = &pfdev->pfdevfreq;

	panfrost_devfreq_update_utilization(pfdevfreq);

	status->current_frequency = clk_get_rate(pfdev->clock);
	status->total_time = ktime_to_ns(ktime_add(pfdevfreq->busy_time,
						   pfdevfreq->idle_time));

	status->busy_time = ktime_to_ns(pfdevfreq->busy_time);

	panfrost_devfreq_reset(pfdevfreq);

	dev_dbg(pfdev->dev, "busy %lu total %lu %lu %% freq %lu MHz\n",
		status->busy_time, status->total_time,
		status->busy_time / (status->total_time / 100),
		status->current_frequency / 1000 / 1000);

	return 0;
}

static struct devfreq_dev_profile panfrost_devfreq_profile = {
	.polling_ms = 50, /* ~3 frames */
	.target = panfrost_devfreq_target,
	.get_dev_status = panfrost_devfreq_get_dev_status,
};

int panfrost_devfreq_init(struct panfrost_device *pfdev)
{
	int ret;
	struct dev_pm_opp *opp;
	unsigned long cur_freq;
	struct device *dev = &pfdev->pdev->dev;
	struct devfreq *devfreq;
	struct thermal_cooling_device *cooling;
	struct panfrost_devfreq *pfdevfreq = &pfdev->pfdevfreq;

	ret = dev_pm_opp_of_add_table(dev);
	if (ret == -ENODEV) /* Optional, continue without devfreq */
		return 0;
	else if (ret)
		return ret;

	panfrost_devfreq_reset(pfdevfreq);

	cur_freq = clk_get_rate(pfdev->clock);

	opp = devfreq_recommended_opp(dev, &cur_freq, 0);
	if (IS_ERR(opp))
		return PTR_ERR(opp);

	panfrost_devfreq_profile.initial_freq = cur_freq;
	dev_pm_opp_put(opp);

	devfreq = devm_devfreq_add_device(dev, &panfrost_devfreq_profile,
					  DEVFREQ_GOV_SIMPLE_ONDEMAND, NULL);
	if (IS_ERR(devfreq)) {
		DRM_DEV_ERROR(dev, "Couldn't initialize GPU devfreq\n");
		dev_pm_opp_of_remove_table(dev);
		return PTR_ERR(devfreq);
	}
	pfdevfreq->devfreq = devfreq;

	cooling = of_devfreq_cooling_register(dev->of_node, devfreq);
	if (IS_ERR(cooling))
		DRM_DEV_INFO(dev, "Failed to register cooling device\n");
	else
		pfdevfreq->cooling = cooling;

	return 0;
}

void panfrost_devfreq_fini(struct panfrost_device *pfdev)
{
	struct panfrost_devfreq *pfdevfreq = &pfdev->pfdevfreq;

	if (pfdevfreq->cooling)
		devfreq_cooling_unregister(pfdevfreq->cooling);
	dev_pm_opp_of_remove_table(&pfdev->pdev->dev);
}

void panfrost_devfreq_resume(struct panfrost_device *pfdev)
{
	struct panfrost_devfreq *pfdevfreq = &pfdev->pfdevfreq;

	if (!pfdevfreq->devfreq)
		return;

	panfrost_devfreq_reset(pfdevfreq);

	devfreq_resume_device(pfdevfreq->devfreq);
}

void panfrost_devfreq_suspend(struct panfrost_device *pfdev)
{
	struct panfrost_devfreq *pfdevfreq = &pfdev->pfdevfreq;

	if (!pfdevfreq->devfreq)
		return;

	devfreq_suspend_device(pfdevfreq->devfreq);
}

void panfrost_devfreq_record_busy(struct panfrost_devfreq *pfdevfreq)
{
	panfrost_devfreq_update_utilization(pfdevfreq);
	atomic_inc(&pfdevfreq->busy_count);
}

void panfrost_devfreq_record_idle(struct panfrost_devfreq *pfdevfreq)
{
	int count;

	panfrost_devfreq_update_utilization(pfdevfreq);
	count = atomic_dec_if_positive(&pfdevfreq->busy_count);
	WARN_ON(count < 0);
}