// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2022 MediaTek Inc.
 */

#include <linux/clk.h>
#include <linux/devfreq.h>
#include <linux/minmax.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_opp.h>
#include <linux/regulator/consumer.h>

struct mtk_ccifreq_platform_data {
        int min_volt_shift;
        int max_volt_shift;
        int proc_max_volt;
        int sram_min_volt;
        int sram_max_volt;
};

struct mtk_ccifreq_drv {
        struct device *dev;
        struct devfreq *devfreq;
        struct regulator *proc_reg;
        struct regulator *sram_reg;
        struct clk *cci_clk;
        struct clk *inter_clk;
        int inter_voltage;
        unsigned long pre_freq;
        /* Avoid race condition for regulators between notify and policy */
        struct mutex reg_lock;
        struct notifier_block opp_nb;
        const struct mtk_ccifreq_platform_data *soc_data;
        int vtrack_max;
};

static int mtk_ccifreq_set_voltage(struct mtk_ccifreq_drv *drv, int new_voltage)
{
        const struct mtk_ccifreq_platform_data *soc_data = drv->soc_data;
        struct device *dev = drv->dev;
        int pre_voltage, pre_vsram, new_vsram, vsram, voltage, ret;
        int retry_max = drv->vtrack_max;

        if (!drv->sram_reg) {
                ret = regulator_set_voltage(drv->proc_reg, new_voltage,
                                            drv->soc_data->proc_max_volt);
                return ret;
        }

        pre_voltage = regulator_get_voltage(drv->proc_reg);
        if (pre_voltage < 0) {
                dev_err(dev, "invalid vproc value: %d\n", pre_voltage);
                return pre_voltage;
        }

        pre_vsram = regulator_get_voltage(drv->sram_reg);
        if (pre_vsram < 0) {
                dev_err(dev, "invalid vsram value: %d\n", pre_vsram);
                return pre_vsram;
        }

        new_vsram = clamp(new_voltage + soc_data->min_volt_shift,
                          soc_data->sram_min_volt, soc_data->sram_max_volt);

        do {
                if (pre_voltage <= new_voltage) {
                        vsram = clamp(pre_voltage + soc_data->max_volt_shift,
                                      soc_data->sram_min_volt, new_vsram);
                        ret = regulator_set_voltage(drv->sram_reg, vsram,
                                                    soc_data->sram_max_volt);
                        if (ret)
                                return ret;

                        if (vsram == soc_data->sram_max_volt ||
                            new_vsram == soc_data->sram_min_volt)
                                voltage = new_voltage;
                        else
                                voltage = vsram - soc_data->min_volt_shift;

                        ret = regulator_set_voltage(drv->proc_reg, voltage,
                                                    soc_data->proc_max_volt);
                        if (ret) {
                                regulator_set_voltage(drv->sram_reg, pre_vsram,
                                                      soc_data->sram_max_volt);
                                return ret;
                        }
                } else {
                        voltage = max(new_voltage,
                                      pre_vsram - soc_data->max_volt_shift);
                        ret = regulator_set_voltage(drv->proc_reg, voltage,
                                                    soc_data->proc_max_volt);
                        if (ret)
                                return ret;

                        if (voltage == new_voltage)
                                vsram = new_vsram;
                        else
                                vsram = max(new_vsram,
                                            voltage + soc_data->min_volt_shift);

                        ret = regulator_set_voltage(drv->sram_reg, vsram,
                                                    soc_data->sram_max_volt);
                        if (ret) {
                                regulator_set_voltage(drv->proc_reg, pre_voltage,
                                                      soc_data->proc_max_volt);
                                return ret;
                        }
                }

                pre_voltage = voltage;
                pre_vsram = vsram;

                if (--retry_max < 0) {
                        dev_err(dev,
                                "over loop count, failed to set voltage\n");
                        return -EINVAL;
                }
        } while (voltage != new_voltage || vsram != new_vsram);

        return 0;
}

static int mtk_ccifreq_target(struct device *dev, unsigned long *freq,
                              u32 flags)
{
        struct mtk_ccifreq_drv *drv = dev_get_drvdata(dev);
        struct clk *cci_pll;
        struct dev_pm_opp *opp;
        unsigned long opp_rate;
        int voltage, pre_voltage, inter_voltage, target_voltage, ret;

        if (!drv)
                return -EINVAL;

        if (drv->pre_freq == *freq)
                return 0;

        mutex_lock(&drv->reg_lock);

        inter_voltage = drv->inter_voltage;
        cci_pll = clk_get_parent(drv->cci_clk);

        opp_rate = *freq;
        opp = devfreq_recommended_opp(dev, &opp_rate, 1);
        if (IS_ERR(opp)) {
                dev_err(dev, "failed to find opp for freq: %ld\n", opp_rate);
                ret = PTR_ERR(opp);
                goto out_unlock;
        }

        voltage = dev_pm_opp_get_voltage(opp);
        dev_pm_opp_put(opp);

        pre_voltage = regulator_get_voltage(drv->proc_reg);
        if (pre_voltage < 0) {
                dev_err(dev, "invalid vproc value: %d\n", pre_voltage);
                ret = pre_voltage;
                goto out_unlock;
        }

        /* scale up: set voltage first then freq. */
        target_voltage = max(inter_voltage, voltage);
        if (pre_voltage <= target_voltage) {
                ret = mtk_ccifreq_set_voltage(drv, target_voltage);
                if (ret) {
                        dev_err(dev, "failed to scale up voltage\n");
                        goto out_restore_voltage;
                }
        }

        /* switch the cci clock to intermediate clock source. */
        ret = clk_set_parent(drv->cci_clk, drv->inter_clk);
        if (ret) {
                dev_err(dev, "failed to re-parent cci clock\n");
                goto out_restore_voltage;
        }

        /* set the original clock to target rate. */
        ret = clk_set_rate(cci_pll, *freq);
        if (ret) {
                dev_err(dev, "failed to set cci pll rate: %d\n", ret);
                clk_set_parent(drv->cci_clk, cci_pll);
                goto out_restore_voltage;
        }

        /* switch the cci clock back to the original clock source. */
        ret = clk_set_parent(drv->cci_clk, cci_pll);
        if (ret) {
                dev_err(dev, "failed to re-parent cci clock\n");
                mtk_ccifreq_set_voltage(drv, inter_voltage);
                goto out_unlock;
        }

        /*
         * If the new voltage is lower than the intermediate voltage or the
         * original voltage, scale down to the new voltage.
         */
        if (voltage < inter_voltage || voltage < pre_voltage) {
                ret = mtk_ccifreq_set_voltage(drv, voltage);
                if (ret) {
                        dev_err(dev, "failed to scale down voltage\n");
                        goto out_unlock;
                }
        }

        drv->pre_freq = *freq;
        mutex_unlock(&drv->reg_lock);

        return 0;

out_restore_voltage:
        mtk_ccifreq_set_voltage(drv, pre_voltage);

out_unlock:
        mutex_unlock(&drv->reg_lock);
        return ret;
}

static int mtk_ccifreq_opp_notifier(struct notifier_block *nb,
                                    unsigned long event, void *data)
{
        struct dev_pm_opp *opp = data;
        struct mtk_ccifreq_drv *drv;
        unsigned long freq, volt;

        drv = container_of(nb, struct mtk_ccifreq_drv, opp_nb);

        if (event == OPP_EVENT_ADJUST_VOLTAGE) {
                mutex_lock(&drv->reg_lock);
                freq = dev_pm_opp_get_freq(opp);

                /* current opp item is changed */
                if (freq == drv->pre_freq) {
                        volt = dev_pm_opp_get_voltage(opp);
                        mtk_ccifreq_set_voltage(drv, volt);
                }
                mutex_unlock(&drv->reg_lock);
        }

        return 0;
}

static struct devfreq_dev_profile mtk_ccifreq_profile = {
        .target = mtk_ccifreq_target,
};

static int mtk_ccifreq_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct mtk_ccifreq_drv *drv;
        struct devfreq_passive_data *passive_data;
        struct dev_pm_opp *opp;
        unsigned long rate, opp_volt;
        int ret;

        drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
        if (!drv)
                return -ENOMEM;

        drv->dev = dev;
        drv->soc_data = (const struct mtk_ccifreq_platform_data *)
                                of_device_get_match_data(&pdev->dev);
        mutex_init(&drv->reg_lock);
        platform_set_drvdata(pdev, drv);

        drv->cci_clk = devm_clk_get(dev, "cci");
        if (IS_ERR(drv->cci_clk)) {
                ret = PTR_ERR(drv->cci_clk);
                return dev_err_probe(dev, ret, "failed to get cci clk\n");
        }

        drv->inter_clk = devm_clk_get(dev, "intermediate");
        if (IS_ERR(drv->inter_clk)) {
                ret = PTR_ERR(drv->inter_clk);
                return dev_err_probe(dev, ret,
                                     "failed to get intermediate clk\n");
        }

        drv->proc_reg = devm_regulator_get_optional(dev, "proc");
        if (IS_ERR(drv->proc_reg)) {
                ret = PTR_ERR(drv->proc_reg);
                return dev_err_probe(dev, ret,
                                     "failed to get proc regulator\n");
        }

        ret = regulator_enable(drv->proc_reg);
        if (ret) {
                dev_err(dev, "failed to enable proc regulator\n");
                return ret;
        }

        drv->sram_reg = devm_regulator_get_optional(dev, "sram");
        if (IS_ERR(drv->sram_reg)) {
                ret = PTR_ERR(drv->sram_reg);
                if (ret == -EPROBE_DEFER)
                        goto out_free_resources;

                drv->sram_reg = NULL;
        } else {
                ret = regulator_enable(drv->sram_reg);
                if (ret) {
                        dev_err(dev, "failed to enable sram regulator\n");
                        goto out_free_resources;
                }
        }

        /*
         * We assume min voltage is 0 and tracking target voltage using
         * min_volt_shift for each iteration.
         * The retry_max is 3 times of expected iteration count.
         */
        drv->vtrack_max = 3 * DIV_ROUND_UP(max(drv->soc_data->sram_max_volt,
                                               drv->soc_data->proc_max_volt),
                                           drv->soc_data->min_volt_shift);

        ret = clk_prepare_enable(drv->cci_clk);
        if (ret)
                goto out_free_resources;

        ret = dev_pm_opp_of_add_table(dev);
        if (ret) {
                dev_err(dev, "failed to add opp table: %d\n", ret);
                goto out_disable_cci_clk;
        }

        rate = clk_get_rate(drv->inter_clk);
        opp = dev_pm_opp_find_freq_ceil(dev, &rate);
        if (IS_ERR(opp)) {
                ret = PTR_ERR(opp);
                dev_err(dev, "failed to get intermediate opp: %d\n", ret);
                goto out_remove_opp_table;
        }
        drv->inter_voltage = dev_pm_opp_get_voltage(opp);
        dev_pm_opp_put(opp);

        rate = U32_MAX;
        opp = dev_pm_opp_find_freq_floor(drv->dev, &rate);
        if (IS_ERR(opp)) {
                dev_err(dev, "failed to get opp\n");
                ret = PTR_ERR(opp);
                goto out_remove_opp_table;
        }

        opp_volt = dev_pm_opp_get_voltage(opp);
        dev_pm_opp_put(opp);
        ret = mtk_ccifreq_set_voltage(drv, opp_volt);
        if (ret) {
                dev_err(dev, "failed to scale to highest voltage %lu in proc_reg\n",
                        opp_volt);
                goto out_remove_opp_table;
        }

        passive_data = devm_kzalloc(dev, sizeof(*passive_data), GFP_KERNEL);
        if (!passive_data) {
                ret = -ENOMEM;
                goto out_remove_opp_table;
        }

        passive_data->parent_type = CPUFREQ_PARENT_DEV;
        drv->devfreq = devm_devfreq_add_device(dev, &mtk_ccifreq_profile,
                                               DEVFREQ_GOV_PASSIVE,
                                               passive_data);
        if (IS_ERR(drv->devfreq)) {
                ret = -EPROBE_DEFER;
                dev_err(dev, "failed to add devfreq device: %ld\n",
                        PTR_ERR(drv->devfreq));
                goto out_remove_opp_table;
        }

        drv->opp_nb.notifier_call = mtk_ccifreq_opp_notifier;
        ret = dev_pm_opp_register_notifier(dev, &drv->opp_nb);
        if (ret) {
                dev_err(dev, "failed to register opp notifier: %d\n", ret);
                goto out_remove_opp_table;
        }
        return 0;

out_remove_opp_table:
        dev_pm_opp_of_remove_table(dev);

out_disable_cci_clk:
        clk_disable_unprepare(drv->cci_clk);

out_free_resources:
        if (regulator_is_enabled(drv->proc_reg))
                regulator_disable(drv->proc_reg);
        if (!IS_ERR_OR_NULL(drv->sram_reg) &&
            regulator_is_enabled(drv->sram_reg))
                regulator_disable(drv->sram_reg);

        return ret;
}

static void mtk_ccifreq_remove(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct mtk_ccifreq_drv *drv;

        drv = platform_get_drvdata(pdev);

        dev_pm_opp_unregister_notifier(dev, &drv->opp_nb);
        dev_pm_opp_of_remove_table(dev);
        clk_disable_unprepare(drv->cci_clk);
        regulator_disable(drv->proc_reg);
        if (drv->sram_reg)
                regulator_disable(drv->sram_reg);
}

static const struct mtk_ccifreq_platform_data mt8183_platform_data = {
        .min_volt_shift = 100000,
        .max_volt_shift = 200000,
        .proc_max_volt = 1150000,
};

static const struct mtk_ccifreq_platform_data mt8186_platform_data = {
        .min_volt_shift = 100000,
        .max_volt_shift = 250000,
        .proc_max_volt = 1118750,
        .sram_min_volt = 850000,
        .sram_max_volt = 1118750,
};

static const struct of_device_id mtk_ccifreq_machines[] = {
        { .compatible = "mediatek,mt8183-cci", .data = &mt8183_platform_data },
        { .compatible = "mediatek,mt8186-cci", .data = &mt8186_platform_data },
        { },
};
MODULE_DEVICE_TABLE(of, mtk_ccifreq_machines);

static struct platform_driver mtk_ccifreq_platdrv = {
        .probe  = mtk_ccifreq_probe,
        .remove = mtk_ccifreq_remove,
        .driver = {
                .name = "mtk-ccifreq",
                .of_match_table = mtk_ccifreq_machines,
        },
};
module_platform_driver(mtk_ccifreq_platdrv);

MODULE_DESCRIPTION("MediaTek CCI devfreq driver");
MODULE_AUTHOR("Jia-Wei Chang <jia-wei.chang@mediatek.com>");
MODULE_LICENSE("GPL v2");