// 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/nvmem-consumer.h>
#include <linux/platform_device.h>
#include <linux/pm_opp.h>

#include <drm/drm_print.h>

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

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

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

        if (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 panfrost_device *pfdev = dev_get_drvdata(dev);
        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)
                pfdev->pfdevfreq.current_frequency = *freq;

        return err;
}

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;
        unsigned long irqflags;

        status->current_frequency = clk_get_rate(pfdev->clock);

        spin_lock_irqsave(&pfdevfreq->lock, irqflags);

        panfrost_devfreq_update_utilization(pfdevfreq);

        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);

        spin_unlock_irqrestore(&pfdevfreq->lock, irqflags);

        dev_dbg(pfdev->base.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 = {
        .timer = DEVFREQ_TIMER_DELAYED,
        .polling_ms = 50, /* ~3 frames */
        .target = panfrost_devfreq_target,
        .get_dev_status = panfrost_devfreq_get_dev_status,
};

static int panfrost_read_speedbin(struct device *dev)
{
        u32 val;
        int ret;

        ret = nvmem_cell_read_variable_le_u32(dev, "speed-bin", &val);
        if (ret) {
                /*
                 * -ENOENT means that this platform doesn't support speedbins
                 * as it didn't declare any speed-bin nvmem: in this case, we
                 * keep going without it; any other error means that we are
                 * supposed to read the bin value, but we failed doing so.
                 */
                if (ret != -ENOENT && ret != -EOPNOTSUPP) {
                        DRM_DEV_ERROR(dev, "Cannot read speed-bin (%d).", ret);
                        return ret;
                }

                return 0;
        }
        DRM_DEV_DEBUG(dev, "Using speed-bin = 0x%x\n", val);

        return devm_pm_opp_set_supported_hw(dev, &val, 1);
}

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

        if (pfdev->comp->num_supplies > 1) {
                /*
                 * GPUs with more than 1 supply require platform-specific handling:
                 * continue without devfreq
                 */
                DRM_DEV_INFO(dev, "More than 1 supply is not supported yet\n");
                return 0;
        }

        ret = panfrost_read_speedbin(dev);
        if (ret)
                return ret;

        ret = devm_pm_opp_set_regulators(dev, pfdev->comp->supply_names);
        if (ret) {
                /* Continue if the optional regulator is missing */
                if (ret != -ENODEV) {
                        if (ret != -EPROBE_DEFER)
                                DRM_DEV_ERROR(dev, "Couldn't set OPP regulators\n");
                        return ret;
                }
        }

        ret = devm_pm_opp_of_add_table(dev);
        if (ret) {
                /* Optional, continue without devfreq */
                if (ret == -ENODEV)
                        ret = 0;
                return ret;
        }
        pfdevfreq->opp_of_table_added = true;

        spin_lock_init(&pfdevfreq->lock);

        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;

        /*
         * We could wait until panfrost_devfreq_target() to set this value, but
         * since the simple_ondemand governor works asynchronously, there's a
         * chance by the time someone opens the device's fdinfo file, current
         * frequency hasn't been updated yet, so let's just do an early set.
         */
        pfdevfreq->current_frequency = cur_freq;

        /*
         * Set the recommend OPP this will enable and configure the regulator
         * if any and will avoid a switch off by regulator_late_cleanup()
         */
        ret = dev_pm_opp_set_opp(dev, opp);
        dev_pm_opp_put(opp);
        if (ret) {
                DRM_DEV_ERROR(dev, "Couldn't set recommended OPP\n");
                return ret;
        }

        /* Find the fastest defined rate  */
        opp = dev_pm_opp_find_freq_floor(dev, &freq);
        if (IS_ERR(opp))
                return PTR_ERR(opp);
        pfdevfreq->fast_rate = freq;

        dev_pm_opp_put(opp);

        /*
         * Setup default thresholds for the simple_ondemand governor.
         * The values are chosen based on experiments.
         */
        pfdevfreq->gov_data.upthreshold = 45;
        pfdevfreq->gov_data.downdifferential = 5;

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

        cooling = devfreq_cooling_em_register(devfreq, NULL);
        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);
                pfdevfreq->cooling = NULL;
        }
}

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)
{
        unsigned long irqflags;

        if (!pfdevfreq->devfreq)
                return;

        spin_lock_irqsave(&pfdevfreq->lock, irqflags);

        panfrost_devfreq_update_utilization(pfdevfreq);

        pfdevfreq->busy_count++;

        spin_unlock_irqrestore(&pfdevfreq->lock, irqflags);
}

void panfrost_devfreq_record_idle(struct panfrost_devfreq *pfdevfreq)
{
        unsigned long irqflags;

        if (!pfdevfreq->devfreq)
                return;

        spin_lock_irqsave(&pfdevfreq->lock, irqflags);

        panfrost_devfreq_update_utilization(pfdevfreq);

        WARN_ON(--pfdevfreq->busy_count < 0);

        spin_unlock_irqrestore(&pfdevfreq->lock, irqflags);
}