/*
 * Copyright (C) 2012 Freescale Semiconductor, Inc.
 *
 * Copyright (C) 2014 Linaro.
 * Viresh Kumar <viresh.kumar@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt

#include <linux/clk.h>
#include <linux/cpu.h>
#include <linux/cpu_cooling.h>
#include <linux/cpufreq.h>
#include <linux/cpumask.h>
#include <linux/err.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 device *cpu_dev;
        struct thermal_cooling_device *cdev;
        const char *reg_name;
};

static struct freq_attr *cpufreq_dt_attr[] = {
        &cpufreq_freq_attr_scaling_available_freqs,
        NULL,   /* Extra space for boost-attr if required */
        NULL,
};

static int set_target(struct cpufreq_policy *policy, unsigned int index)
{
        struct private_data *priv = policy->driver_data;

        return dev_pm_opp_set_rate(priv->cpu_dev,
                                   policy->freq_table[index].frequency * 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;
        struct property *pp;
        int cpu = dev->id;
        const char *name = NULL;

        np = of_node_get(dev->of_node);

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

        /* Try "cpu0" for older DTs */
        if (!cpu) {
                pp = of_find_property(np, "cpu0-supply", NULL);
                if (pp) {
                        name = "cpu0";
                        goto node_put;
                }
        }

        pp = of_find_property(np, "cpu-supply", NULL);
        if (pp) {
                name = "cpu";
                goto node_put;
        }

        dev_dbg(dev, "no regulator for cpu%d\n", cpu);
node_put:
        of_node_put(np);
        return name;
}

static int resources_available(void)
{
        struct device *cpu_dev;
        struct regulator *cpu_reg;
        struct clk *cpu_clk;
        int ret = 0;
        const char *name;

        cpu_dev = get_cpu_device(0);
        if (!cpu_dev) {
                pr_err("failed to get cpu0 device\n");
                return -ENODEV;
        }

        cpu_clk = clk_get(cpu_dev, NULL);
        ret = PTR_ERR_OR_ZERO(cpu_clk);
        if (ret) {
                /*
                 * If cpu's clk node is present, but clock is not yet
                 * registered, we should try defering probe.
                 */
                if (ret == -EPROBE_DEFER)
                        dev_dbg(cpu_dev, "clock not ready, retry\n");
                else
                        dev_err(cpu_dev, "failed to get clock: %d\n", ret);

                return ret;
        }

        clk_put(cpu_clk);

        name = find_supply_name(cpu_dev);
        /* Platform doesn't require regulator */
        if (!name)
                return 0;

        cpu_reg = regulator_get_optional(cpu_dev, name);
        ret = PTR_ERR_OR_ZERO(cpu_reg);
        if (ret) {
                /*
                 * If cpu's regulator supply node is present, but regulator is
                 * not yet registered, we should try defering probe.
                 */
                if (ret == -EPROBE_DEFER)
                        dev_dbg(cpu_dev, "cpu0 regulator not ready, retry\n");
                else
                        dev_dbg(cpu_dev, "no regulator for cpu0: %d\n", ret);

                return ret;
        }

        regulator_put(cpu_reg);
        return 0;
}

static int cpufreq_init(struct cpufreq_policy *policy)
{
        struct cpufreq_frequency_table *freq_table;
        struct private_data *priv;
        struct device *cpu_dev;
        struct clk *cpu_clk;
        struct dev_pm_opp *suspend_opp;
        unsigned int transition_latency;
        bool fallback = false;
        const char *name;
        int ret;

        cpu_dev = get_cpu_device(policy->cpu);
        if (!cpu_dev) {
                pr_err("failed to get cpu%d device\n", policy->cpu);
                return -ENODEV;
        }

        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;
        }

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

                /*
                 * operating-points-v2 not supported, fallback to old method of
                 * finding shared-OPPs for backward compatibility if the
                 * platform hasn't set sharing CPUs.
                 */
                if (dev_pm_opp_get_sharing_cpus(cpu_dev, policy->cpus))
                        fallback = true;
        }

        /*
         * OPP layer will be taking care of regulators now, but it needs to know
         * the name of the regulator first.
         */
        name = find_supply_name(cpu_dev);
        if (name) {
                ret = dev_pm_opp_set_regulator(cpu_dev, name);
                if (ret) {
                        dev_err(cpu_dev, "Failed to set regulator for cpu%d: %d\n",
                                policy->cpu, ret);
                        goto out_put_clk;
                }
        }

        /*
         * Initialize OPP tables for all policy->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 policy->cpus. Otherwise, we will end up creating
         * duplicate OPPs for policy->cpus.
         *
         * OPPs might be populated at runtime, don't check for error here
         */
        dev_pm_opp_of_cpumask_add_table(policy->cpus);

        /*
         * But we need OPP table to function so if it is not there let's
         * give platform code chance to provide it for us.
         */
        ret = dev_pm_opp_get_opp_count(cpu_dev);
        if (ret <= 0) {
                dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");
                ret = -EPROBE_DEFER;
                goto out_free_opp;
        }

        if (fallback) {
                cpumask_setall(policy->cpus);

                /*
                 * OPP tables are initialized only for policy->cpu, do it for
                 * others as well.
                 */
                ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);
                if (ret)
                        dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
                                __func__, ret);
        }

        priv = kzalloc(sizeof(*priv), GFP_KERNEL);
        if (!priv) {
                ret = -ENOMEM;
                goto out_free_opp;
        }

        priv->reg_name = name;

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

        priv->cpu_dev = cpu_dev;
        policy->driver_data = priv;
        policy->clk = cpu_clk;

        rcu_read_lock();
        suspend_opp = dev_pm_opp_get_suspend_opp(cpu_dev);
        if (suspend_opp)
                policy->suspend_freq = dev_pm_opp_get_freq(suspend_opp) / 1000;
        rcu_read_unlock();

        ret = cpufreq_table_validate_and_show(policy, freq_table);
        if (ret) {
                dev_err(cpu_dev, "%s: invalid frequency table: %d\n", __func__,
                        ret);
                goto out_free_cpufreq_table;
        }

        /* Support turbo/boost mode */
        if (policy_has_boost_freq(policy)) {
                /* This gets disabled by core on driver unregister */
                ret = cpufreq_enable_boost_support();
                if (ret)
                        goto out_free_cpufreq_table;
                cpufreq_dt_attr[1] = &cpufreq_freq_attr_scaling_boost_freqs;
        }

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

        policy->cpuinfo.transition_latency = transition_latency;

        return 0;

out_free_cpufreq_table:
        dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
out_free_priv:
        kfree(priv);
out_free_opp:
        dev_pm_opp_of_cpumask_remove_table(policy->cpus);
        if (name)
                dev_pm_opp_put_regulator(cpu_dev);
out_put_clk:
        clk_put(cpu_clk);

        return ret;
}

static int cpufreq_exit(struct cpufreq_policy *policy)
{
        struct private_data *priv = policy->driver_data;

        cpufreq_cooling_unregister(priv->cdev);
        dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
        dev_pm_opp_of_cpumask_remove_table(policy->related_cpus);
        if (priv->reg_name)
                dev_pm_opp_put_regulator(priv->cpu_dev);

        clk_put(policy->clk);
        kfree(priv);

        return 0;
}

static void cpufreq_ready(struct cpufreq_policy *policy)
{
        struct private_data *priv = policy->driver_data;
        struct device_node *np = of_node_get(priv->cpu_dev->of_node);

        if (WARN_ON(!np))
                return;

        /*
         * For now, just loading the cooling device;
         * thermal DT code takes care of matching them.
         */
        if (of_find_property(np, "#cooling-cells", NULL)) {
                u32 power_coefficient = 0;

                of_property_read_u32(np, "dynamic-power-coefficient",
                                     &power_coefficient);

                priv->cdev = of_cpufreq_power_cooling_register(np,
                                policy->related_cpus, power_coefficient, NULL);
                if (IS_ERR(priv->cdev)) {
                        dev_err(priv->cpu_dev,
                                "running cpufreq without cooling device: %ld\n",
                                PTR_ERR(priv->cdev));

                        priv->cdev = NULL;
                }
        }

        of_node_put(np);
}

static struct cpufreq_driver dt_cpufreq_driver = {
        .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
        .verify = cpufreq_generic_frequency_table_verify,
        .target_index = set_target,
        .get = cpufreq_generic_get,
        .init = cpufreq_init,
        .exit = cpufreq_exit,
        .ready = cpufreq_ready,
        .name = "cpufreq-dt",
        .attr = cpufreq_dt_attr,
        .suspend = cpufreq_generic_suspend,
};

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

        /*
         * All per-cluster (CPUs sharing clock/voltages) initialization is done
         * from ->init(). In probe(), we just need to make sure that clk and
         * regulators are available. Else defer probe and retry.
         *
         * FIXME: Is checking this only for CPU0 sufficient ?
         */
        ret = resources_available();
        if (ret)
                return ret;

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

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

        return ret;
}

static int dt_cpufreq_remove(struct platform_device *pdev)
{
        cpufreq_unregister_driver(&dt_cpufreq_driver);
        return 0;
}

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);

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");