// SPDX-License-Identifier: GPL-2.0
/* Copyright 2019 Collabora ltd. */
#include <linux/devfreq.h>
#include <linux/platform_device.h>
#include <linux/pm_opp.h>
#include <linux/clk.h>
#include <linux/regulator/consumer.h>

#include "panfrost_device.h"
#include "panfrost_devfreq.h"
#include "panfrost_features.h"
#include "panfrost_issues.h"
#include "panfrost_gpu.h"
#include "panfrost_regs.h"

static void panfrost_devfreq_update_utilization(struct panfrost_device *pfdev, int slot);

static int panfrost_devfreq_target(struct device *dev, unsigned long *freq,
                                   u32 flags)
{
        struct panfrost_device *pfdev = platform_get_drvdata(to_platform_device(dev));
        struct dev_pm_opp *opp;
        unsigned long old_clk_rate = pfdev->devfreq.cur_freq;
        unsigned long target_volt, target_rate;
        int err;

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

        target_rate = dev_pm_opp_get_freq(opp);
        target_volt = dev_pm_opp_get_voltage(opp);
        dev_pm_opp_put(opp);

        if (old_clk_rate == target_rate)
                return 0;

        /*
         * If frequency scaling from low to high, adjust voltage first.
         * If frequency scaling from high to low, adjust frequency first.
         */
        if (old_clk_rate < target_rate) {
                err = regulator_set_voltage(pfdev->regulator, target_volt,
                                            target_volt);
                if (err) {
                        dev_err(dev, "Cannot set voltage %lu uV\n",
                                target_volt);
                        return err;
                }
        }

        err = clk_set_rate(pfdev->clock, target_rate);
        if (err) {
                dev_err(dev, "Cannot set frequency %lu (%d)\n", target_rate,
                        err);
                regulator_set_voltage(pfdev->regulator, pfdev->devfreq.cur_volt,
                                      pfdev->devfreq.cur_volt);
                return err;
        }

        if (old_clk_rate > target_rate) {
                err = regulator_set_voltage(pfdev->regulator, target_volt,
                                            target_volt);
                if (err)
                        dev_err(dev, "Cannot set voltage %lu uV\n", target_volt);
        }

        pfdev->devfreq.cur_freq = target_rate;
        pfdev->devfreq.cur_volt = target_volt;

        return 0;
}

static void panfrost_devfreq_reset(struct panfrost_device *pfdev)
{
        ktime_t now = ktime_get();
        int i;

        for (i = 0; i < NUM_JOB_SLOTS; i++) {
                pfdev->devfreq.slot[i].busy_time = 0;
                pfdev->devfreq.slot[i].idle_time = 0;
                pfdev->devfreq.slot[i].time_last_update = now;
        }
}

static int panfrost_devfreq_get_dev_status(struct device *dev,
                                           struct devfreq_dev_status *status)
{
        struct panfrost_device *pfdev = platform_get_drvdata(to_platform_device(dev));
        int i;

        for (i = 0; i < NUM_JOB_SLOTS; i++) {
                panfrost_devfreq_update_utilization(pfdev, i);
        }

        status->current_frequency = clk_get_rate(pfdev->clock);
        status->total_time = ktime_to_ns(ktime_add(pfdev->devfreq.slot[0].busy_time,
                                                   pfdev->devfreq.slot[0].idle_time));

        status->busy_time = 0;
        for (i = 0; i < NUM_JOB_SLOTS; i++) {
                status->busy_time += ktime_to_ns(pfdev->devfreq.slot[i].busy_time);
        }

        /* We're scheduling only to one core atm, so don't divide for now */
        /* status->busy_time /= NUM_JOB_SLOTS; */

        panfrost_devfreq_reset(pfdev);

        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 int panfrost_devfreq_get_cur_freq(struct device *dev, unsigned long *freq)
{
        struct panfrost_device *pfdev = platform_get_drvdata(to_platform_device(dev));

        *freq = pfdev->devfreq.cur_freq;

        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,
        .get_cur_freq = panfrost_devfreq_get_cur_freq,
};

int panfrost_devfreq_init(struct panfrost_device *pfdev)
{
        int ret;
        struct dev_pm_opp *opp;

        if (!pfdev->regulator)
                return 0;

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

        panfrost_devfreq_reset(pfdev);

        pfdev->devfreq.cur_freq = clk_get_rate(pfdev->clock);

        opp = devfreq_recommended_opp(&pfdev->pdev->dev, &pfdev->devfreq.cur_freq, 0);
        if (IS_ERR(opp))
                return PTR_ERR(opp);

        panfrost_devfreq_profile.initial_freq = pfdev->devfreq.cur_freq;
        dev_pm_opp_put(opp);

        pfdev->devfreq.devfreq = devm_devfreq_add_device(&pfdev->pdev->dev,
                        &panfrost_devfreq_profile, "simple_ondemand", NULL);
        if (IS_ERR(pfdev->devfreq.devfreq)) {
                DRM_DEV_ERROR(&pfdev->pdev->dev, "Couldn't initialize GPU devfreq\n");
                ret = PTR_ERR(pfdev->devfreq.devfreq);
                pfdev->devfreq.devfreq = NULL;
                return ret;
        }

        return 0;
}

void panfrost_devfreq_resume(struct panfrost_device *pfdev)
{
        int i;

        if (!pfdev->devfreq.devfreq)
                return;

        panfrost_devfreq_reset(pfdev);
        for (i = 0; i < NUM_JOB_SLOTS; i++)
                pfdev->devfreq.slot[i].busy = false;

        devfreq_resume_device(pfdev->devfreq.devfreq);
}

void panfrost_devfreq_suspend(struct panfrost_device *pfdev)
{
        if (!pfdev->devfreq.devfreq)
                return;

        devfreq_suspend_device(pfdev->devfreq.devfreq);
}

static void panfrost_devfreq_update_utilization(struct panfrost_device *pfdev, int slot)
{
        struct panfrost_devfreq_slot *devfreq_slot = &pfdev->devfreq.slot[slot];
        ktime_t now;
        ktime_t last;

        if (!pfdev->devfreq.devfreq)
                return;

        now = ktime_get();
        last = pfdev->devfreq.slot[slot].time_last_update;

        /* If we last recorded a transition to busy, we have been idle since */
        if (devfreq_slot->busy)
                pfdev->devfreq.slot[slot].busy_time += ktime_sub(now, last);
        else
                pfdev->devfreq.slot[slot].idle_time += ktime_sub(now, last);

        pfdev->devfreq.slot[slot].time_last_update = now;
}

/* The job scheduler is expected to call this at every transition busy <-> idle */
void panfrost_devfreq_record_transition(struct panfrost_device *pfdev, int slot)
{
        struct panfrost_devfreq_slot *devfreq_slot = &pfdev->devfreq.slot[slot];

        panfrost_devfreq_update_utilization(pfdev, slot);
        devfreq_slot->busy = !devfreq_slot->busy;
}