// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2012 Freescale Semiconductor, Inc.
 *
 * Copyright (C) 2014 Linaro.
 * Viresh Kumar <viresh.kumar@linaro.org>
 */

#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt

#include <linux/clk.h>
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/cpumask.h>
#include <linux/err.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/pm_opp.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
#include <linux/thermal.h>

#include "cpufreq-dt.h"

struct private_data {
        struct list_head node;

        cpumask_var_t cpus;
        struct device *cpu_dev;
        struct cpufreq_frequency_table *freq_table;
        bool have_static_opps;
        int opp_token;
};

static LIST_HEAD(priv_list);

static struct private_data *cpufreq_dt_find_data(int cpu)
{
        struct private_data *priv;

        list_for_each_entry(priv, &priv_list, node) {
                if (cpumask_test_cpu(cpu, priv->cpus))
                        return priv;
        }

        return NULL;
}

static int set_target(struct cpufreq_policy *policy, unsigned int index)
{
        struct private_data *priv = policy->driver_data;
        unsigned long freq = policy->freq_table[index].frequency;

        return dev_pm_opp_set_rate(priv->cpu_dev, freq * 1000);
}

/*
 * An earlier version of opp-v1 bindings used to name the regulator
 * "cpu0-supply", we still need to handle that for backwards compatibility.
 */
static const char *find_supply_name(struct device *dev)
{
        struct device_node *np __free(device_node) = of_node_get(dev->of_node);
        int cpu = dev->id;

        /* This must be valid for sure */
        if (WARN_ON(!np))
                return NULL;

        /* Try "cpu0" for older DTs */
        if (!cpu && of_property_present(np, "cpu0-supply"))
                return "cpu0";

        if (of_property_present(np, "cpu-supply"))
                return "cpu";

        dev_dbg(dev, "no regulator for cpu%d\n", cpu);
        return NULL;
}

static int cpufreq_init(struct cpufreq_policy *policy)
{
        struct private_data *priv;
        struct device *cpu_dev;
        struct clk *cpu_clk;
        unsigned int transition_latency;
        int ret;

        priv = cpufreq_dt_find_data(policy->cpu);
        if (!priv) {
                pr_err("failed to find data for cpu%d\n", policy->cpu);
                return -ENODEV;
        }
        cpu_dev = priv->cpu_dev;

        cpu_clk = clk_get(cpu_dev, NULL);
        if (IS_ERR(cpu_clk)) {
                ret = PTR_ERR(cpu_clk);
                dev_err(cpu_dev, "%s: failed to get clk: %d\n", __func__, ret);
                return ret;
        }

        transition_latency = dev_pm_opp_get_max_transition_latency(cpu_dev);
        if (!transition_latency)
                transition_latency = CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS;

        cpumask_copy(policy->cpus, priv->cpus);
        policy->driver_data = priv;
        policy->clk = cpu_clk;
        policy->freq_table = priv->freq_table;
        policy->suspend_freq = dev_pm_opp_get_suspend_opp_freq(cpu_dev) / 1000;
        policy->cpuinfo.transition_latency = transition_latency;
        policy->dvfs_possible_from_any_cpu = true;

        return 0;
}

static int cpufreq_online(struct cpufreq_policy *policy)
{
        /* We did light-weight tear down earlier, nothing to do here */
        return 0;
}

static int cpufreq_offline(struct cpufreq_policy *policy)
{
        /*
         * Preserve policy->driver_data and don't free resources on light-weight
         * tear down.
         */
        return 0;
}

static void cpufreq_exit(struct cpufreq_policy *policy)
{
        clk_put(policy->clk);
}

static struct cpufreq_driver dt_cpufreq_driver = {
        .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK |
                 CPUFREQ_IS_COOLING_DEV,
        .verify = cpufreq_generic_frequency_table_verify,
        .target_index = set_target,
        .get = cpufreq_generic_get,
        .init = cpufreq_init,
        .exit = cpufreq_exit,
        .online = cpufreq_online,
        .offline = cpufreq_offline,
        .register_em = cpufreq_register_em_with_opp,
        .name = "cpufreq-dt",
        .set_boost = cpufreq_boost_set_sw,
        .suspend = cpufreq_generic_suspend,
};

static int dt_cpufreq_early_init(struct device *dev, int cpu)
{
        struct private_data *priv;
        struct device *cpu_dev;
        bool fallback = false;
        const char *reg_name[] = { NULL, NULL };
        int ret;

        /* Check if this CPU is already covered by some other policy */
        if (cpufreq_dt_find_data(cpu))
                return 0;

        cpu_dev = get_cpu_device(cpu);
        if (!cpu_dev)
                return -EPROBE_DEFER;

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

        if (!zalloc_cpumask_var(&priv->cpus, GFP_KERNEL))
                return -ENOMEM;

        cpumask_set_cpu(cpu, priv->cpus);
        priv->cpu_dev = cpu_dev;

        /*
         * OPP layer will be taking care of regulators now, but it needs to know
         * the name of the regulator first.
         */
        reg_name[0] = find_supply_name(cpu_dev);
        if (reg_name[0]) {
                priv->opp_token = dev_pm_opp_set_regulators(cpu_dev, reg_name);
                if (priv->opp_token < 0) {
                        ret = dev_err_probe(cpu_dev, priv->opp_token,
                                            "failed to set regulators\n");
                        goto free_cpumask;
                }
        }

        /* Get OPP-sharing information from "operating-points-v2" bindings */
        ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, priv->cpus);
        if (ret) {
                if (ret != -ENOENT)
                        goto out;

                /*
                 * operating-points-v2 not supported, fallback to all CPUs share
                 * OPP for backward compatibility if the platform hasn't set
                 * sharing CPUs.
                 */
                if (dev_pm_opp_get_sharing_cpus(cpu_dev, priv->cpus))
                        fallback = true;
        }

        /*
         * Initialize OPP tables for all priv->cpus. They will be shared by
         * all CPUs which have marked their CPUs shared with OPP bindings.
         *
         * For platforms not using operating-points-v2 bindings, we do this
         * before updating priv->cpus. Otherwise, we will end up creating
         * duplicate OPPs for the CPUs.
         *
         * OPPs might be populated at runtime, don't fail for error here unless
         * it is -EPROBE_DEFER.
         */
        ret = dev_pm_opp_of_cpumask_add_table(priv->cpus);
        if (!ret) {
                priv->have_static_opps = true;
        } else if (ret == -EPROBE_DEFER) {
                goto out;
        }

        /*
         * The OPP table must be initialized, statically or dynamically, by this
         * point.
         */
        ret = dev_pm_opp_get_opp_count(cpu_dev);
        if (ret <= 0) {
                dev_err(cpu_dev, "OPP table can't be empty\n");
                ret = -ENODEV;
                goto out;
        }

        if (fallback) {
                cpumask_setall(priv->cpus);
                ret = dev_pm_opp_set_sharing_cpus(cpu_dev, priv->cpus);
                if (ret)
                        dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
                                __func__, ret);
        }

        ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &priv->freq_table);
        if (ret) {
                dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
                goto out;
        }

        list_add(&priv->node, &priv_list);
        return 0;

out:
        if (priv->have_static_opps)
                dev_pm_opp_of_cpumask_remove_table(priv->cpus);
        dev_pm_opp_put_regulators(priv->opp_token);
free_cpumask:
        free_cpumask_var(priv->cpus);
        return ret;
}

static void dt_cpufreq_release(void)
{
        struct private_data *priv, *tmp;

        list_for_each_entry_safe(priv, tmp, &priv_list, node) {
                dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &priv->freq_table);
                if (priv->have_static_opps)
                        dev_pm_opp_of_cpumask_remove_table(priv->cpus);
                dev_pm_opp_put_regulators(priv->opp_token);
                free_cpumask_var(priv->cpus);
                list_del(&priv->node);
        }
}

static int dt_cpufreq_probe(struct platform_device *pdev)
{
        struct cpufreq_dt_platform_data *data = dev_get_platdata(&pdev->dev);
        int ret, cpu;

        /* Request resources early so we can return in case of -EPROBE_DEFER */
        for_each_present_cpu(cpu) {
                ret = dt_cpufreq_early_init(&pdev->dev, cpu);
                if (ret)
                        goto err;
        }

        if (data) {
                if (data->have_governor_per_policy)
                        dt_cpufreq_driver.flags |= CPUFREQ_HAVE_GOVERNOR_PER_POLICY;

                dt_cpufreq_driver.resume = data->resume;
                if (data->suspend)
                        dt_cpufreq_driver.suspend = data->suspend;
                if (data->get_intermediate) {
                        dt_cpufreq_driver.target_intermediate = data->target_intermediate;
                        dt_cpufreq_driver.get_intermediate = data->get_intermediate;
                }
        }

        ret = cpufreq_register_driver(&dt_cpufreq_driver);
        if (ret) {
                dev_err(&pdev->dev, "failed register driver: %d\n", ret);
                goto err;
        }

        return 0;
err:
        dt_cpufreq_release();
        return ret;
}

static void dt_cpufreq_remove(struct platform_device *pdev)
{
        cpufreq_unregister_driver(&dt_cpufreq_driver);
        dt_cpufreq_release();
}

static struct platform_driver dt_cpufreq_platdrv = {
        .driver = {
                .name   = "cpufreq-dt",
        },
        .probe          = dt_cpufreq_probe,
        .remove         = dt_cpufreq_remove,
};
module_platform_driver(dt_cpufreq_platdrv);

struct platform_device *cpufreq_dt_pdev_register(struct device *dev)
{
        struct platform_device_info cpufreq_dt_devinfo = {};

        cpufreq_dt_devinfo.name = "cpufreq-dt";
        cpufreq_dt_devinfo.parent = dev;

        return platform_device_register_full(&cpufreq_dt_devinfo);
}
EXPORT_SYMBOL_GPL(cpufreq_dt_pdev_register);

MODULE_ALIAS("platform:cpufreq-dt");
MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
MODULE_DESCRIPTION("Generic cpufreq driver");
MODULE_LICENSE("GPL");