// SPDX-License-Identifier: GPL-2.0
/*
 * Versatile Express SPC CPUFreq Interface driver
 *
 * Copyright (C) 2013 - 2019 ARM Ltd.
 * Sudeep Holla <sudeep.holla@arm.com>
 *
 * Copyright (C) 2013 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/cpu_cooling.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/pm_opp.h>
#include <linux/slab.h>
#include <linux/topology.h>
#include <linux/types.h>

/* Currently we support only two clusters */
#define A15_CLUSTER     0
#define A7_CLUSTER      1
#define MAX_CLUSTERS    2

#ifdef CONFIG_BL_SWITCHER
#include <asm/bL_switcher.h>
static bool bL_switching_enabled;
#define is_bL_switching_enabled()       bL_switching_enabled
#define set_switching_enabled(x)        (bL_switching_enabled = (x))
#else
#define is_bL_switching_enabled()       false
#define set_switching_enabled(x)        do { } while (0)
#define bL_switch_request(...)          do { } while (0)
#define bL_switcher_put_enabled()       do { } while (0)
#define bL_switcher_get_enabled()       do { } while (0)
#endif

#define ACTUAL_FREQ(cluster, freq)  ((cluster == A7_CLUSTER) ? freq << 1 : freq)
#define VIRT_FREQ(cluster, freq)    ((cluster == A7_CLUSTER) ? freq >> 1 : freq)

static struct thermal_cooling_device *cdev[MAX_CLUSTERS];
static struct clk *clk[MAX_CLUSTERS];
static struct cpufreq_frequency_table *freq_table[MAX_CLUSTERS + 1];
static atomic_t cluster_usage[MAX_CLUSTERS + 1];

static unsigned int clk_big_min;        /* (Big) clock frequencies */
static unsigned int clk_little_max;     /* Maximum clock frequency (Little) */

static DEFINE_PER_CPU(unsigned int, physical_cluster);
static DEFINE_PER_CPU(unsigned int, cpu_last_req_freq);

static struct mutex cluster_lock[MAX_CLUSTERS];

static inline int raw_cpu_to_cluster(int cpu)
{
        return topology_physical_package_id(cpu);
}

static inline int cpu_to_cluster(int cpu)
{
        return is_bL_switching_enabled() ?
                MAX_CLUSTERS : raw_cpu_to_cluster(cpu);
}

static unsigned int find_cluster_maxfreq(int cluster)
{
        int j;
        u32 max_freq = 0, cpu_freq;

        for_each_online_cpu(j) {
                cpu_freq = per_cpu(cpu_last_req_freq, j);

                if (cluster == per_cpu(physical_cluster, j) &&
                    max_freq < cpu_freq)
                        max_freq = cpu_freq;
        }

        return max_freq;
}

static unsigned int clk_get_cpu_rate(unsigned int cpu)
{
        u32 cur_cluster = per_cpu(physical_cluster, cpu);
        u32 rate = clk_get_rate(clk[cur_cluster]) / 1000;

        /* For switcher we use virtual A7 clock rates */
        if (is_bL_switching_enabled())
                rate = VIRT_FREQ(cur_cluster, rate);

        return rate;
}

static unsigned int ve_spc_cpufreq_get_rate(unsigned int cpu)
{
        if (is_bL_switching_enabled())
                return per_cpu(cpu_last_req_freq, cpu);
        else
                return clk_get_cpu_rate(cpu);
}

static unsigned int
ve_spc_cpufreq_set_rate(u32 cpu, u32 old_cluster, u32 new_cluster, u32 rate)
{
        u32 new_rate, prev_rate;
        int ret;
        bool bLs = is_bL_switching_enabled();

        mutex_lock(&cluster_lock[new_cluster]);

        if (bLs) {
                prev_rate = per_cpu(cpu_last_req_freq, cpu);
                per_cpu(cpu_last_req_freq, cpu) = rate;
                per_cpu(physical_cluster, cpu) = new_cluster;

                new_rate = find_cluster_maxfreq(new_cluster);
                new_rate = ACTUAL_FREQ(new_cluster, new_rate);
        } else {
                new_rate = rate;
        }

        ret = clk_set_rate(clk[new_cluster], new_rate * 1000);
        if (!ret) {
                /*
                 * FIXME: clk_set_rate hasn't returned an error here however it
                 * may be that clk_change_rate failed due to hardware or
                 * firmware issues and wasn't able to report that due to the
                 * current design of the clk core layer. To work around this
                 * problem we will read back the clock rate and check it is
                 * correct. This needs to be removed once clk core is fixed.
                 */
                if (clk_get_rate(clk[new_cluster]) != new_rate * 1000)
                        ret = -EIO;
        }

        if (WARN_ON(ret)) {
                if (bLs) {
                        per_cpu(cpu_last_req_freq, cpu) = prev_rate;
                        per_cpu(physical_cluster, cpu) = old_cluster;
                }

                mutex_unlock(&cluster_lock[new_cluster]);

                return ret;
        }

        mutex_unlock(&cluster_lock[new_cluster]);

        /* Recalc freq for old cluster when switching clusters */
        if (old_cluster != new_cluster) {
                /* Switch cluster */
                bL_switch_request(cpu, new_cluster);

                mutex_lock(&cluster_lock[old_cluster]);

                /* Set freq of old cluster if there are cpus left on it */
                new_rate = find_cluster_maxfreq(old_cluster);
                new_rate = ACTUAL_FREQ(old_cluster, new_rate);

                if (new_rate &&
                    clk_set_rate(clk[old_cluster], new_rate * 1000)) {
                        pr_err("%s: clk_set_rate failed: %d, old cluster: %d\n",
                               __func__, ret, old_cluster);
                }
                mutex_unlock(&cluster_lock[old_cluster]);
        }

        return 0;
}

/* Set clock frequency */
static int ve_spc_cpufreq_set_target(struct cpufreq_policy *policy,
                                     unsigned int index)
{
        u32 cpu = policy->cpu, cur_cluster, new_cluster, actual_cluster;
        unsigned int freqs_new;
        int ret;

        cur_cluster = cpu_to_cluster(cpu);
        new_cluster = actual_cluster = per_cpu(physical_cluster, cpu);

        freqs_new = freq_table[cur_cluster][index].frequency;

        if (is_bL_switching_enabled()) {
                if (actual_cluster == A15_CLUSTER && freqs_new < clk_big_min)
                        new_cluster = A7_CLUSTER;
                else if (actual_cluster == A7_CLUSTER &&
                         freqs_new > clk_little_max)
                        new_cluster = A15_CLUSTER;
        }

        ret = ve_spc_cpufreq_set_rate(cpu, actual_cluster, new_cluster,
                                      freqs_new);

        if (!ret) {
                arch_set_freq_scale(policy->related_cpus, freqs_new,
                                    policy->cpuinfo.max_freq);
        }

        return ret;
}

static inline u32 get_table_count(struct cpufreq_frequency_table *table)
{
        int count;

        for (count = 0; table[count].frequency != CPUFREQ_TABLE_END; count++)
                ;

        return count;
}

/* get the minimum frequency in the cpufreq_frequency_table */
static inline u32 get_table_min(struct cpufreq_frequency_table *table)
{
        struct cpufreq_frequency_table *pos;
        u32 min_freq = ~0;

        cpufreq_for_each_entry(pos, table)
                if (pos->frequency < min_freq)
                        min_freq = pos->frequency;
        return min_freq;
}

/* get the maximum frequency in the cpufreq_frequency_table */
static inline u32 get_table_max(struct cpufreq_frequency_table *table)
{
        struct cpufreq_frequency_table *pos;
        u32 max_freq = 0;

        cpufreq_for_each_entry(pos, table)
                if (pos->frequency > max_freq)
                        max_freq = pos->frequency;
        return max_freq;
}

static bool search_frequency(struct cpufreq_frequency_table *table, int size,
                             unsigned int freq)
{
        int count;

        for (count = 0; count < size; count++) {
                if (table[count].frequency == freq)
                        return true;
        }

        return false;
}

static int merge_cluster_tables(void)
{
        int i, j, k = 0, count = 1;
        struct cpufreq_frequency_table *table;

        for (i = 0; i < MAX_CLUSTERS; i++)
                count += get_table_count(freq_table[i]);

        table = kcalloc(count, sizeof(*table), GFP_KERNEL);
        if (!table)
                return -ENOMEM;

        freq_table[MAX_CLUSTERS] = table;

        /* Add in reverse order to get freqs in increasing order */
        for (i = MAX_CLUSTERS - 1; i >= 0; i--, count = k) {
                for (j = 0; freq_table[i][j].frequency != CPUFREQ_TABLE_END;
                     j++) {
                        if (i == A15_CLUSTER &&
                            search_frequency(table, count, freq_table[i][j].frequency))
                                continue; /* skip duplicates */
                        table[k++].frequency =
                                VIRT_FREQ(i, freq_table[i][j].frequency);
                }
        }

        table[k].driver_data = k;
        table[k].frequency = CPUFREQ_TABLE_END;

        return 0;
}

static void _put_cluster_clk_and_freq_table(struct device *cpu_dev,
                                            const struct cpumask *cpumask)
{
        u32 cluster = raw_cpu_to_cluster(cpu_dev->id);

        if (!freq_table[cluster])
                return;

        clk_put(clk[cluster]);
        dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
}

static void put_cluster_clk_and_freq_table(struct device *cpu_dev,
                                           const struct cpumask *cpumask)
{
        u32 cluster = cpu_to_cluster(cpu_dev->id);
        int i;

        if (atomic_dec_return(&cluster_usage[cluster]))
                return;

        if (cluster < MAX_CLUSTERS)
                return _put_cluster_clk_and_freq_table(cpu_dev, cpumask);

        for_each_present_cpu(i) {
                struct device *cdev = get_cpu_device(i);

                if (!cdev)
                        return;

                _put_cluster_clk_and_freq_table(cdev, cpumask);
        }

        /* free virtual table */
        kfree(freq_table[cluster]);
}

static int _get_cluster_clk_and_freq_table(struct device *cpu_dev,
                                           const struct cpumask *cpumask)
{
        u32 cluster = raw_cpu_to_cluster(cpu_dev->id);
        int ret;

        if (freq_table[cluster])
                return 0;

        /*
         * platform specific SPC code must initialise the opp table
         * so just check if the OPP count is non-zero
         */
        ret = dev_pm_opp_get_opp_count(cpu_dev) <= 0;
        if (ret)
                goto out;

        ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table[cluster]);
        if (ret)
                goto out;

        clk[cluster] = clk_get(cpu_dev, NULL);
        if (!IS_ERR(clk[cluster]))
                return 0;

        dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d, cluster: %d\n",
                __func__, cpu_dev->id, cluster);
        ret = PTR_ERR(clk[cluster]);
        dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);

out:
        dev_err(cpu_dev, "%s: Failed to get data for cluster: %d\n", __func__,
                cluster);
        return ret;
}

static int get_cluster_clk_and_freq_table(struct device *cpu_dev,
                                          const struct cpumask *cpumask)
{
        u32 cluster = cpu_to_cluster(cpu_dev->id);
        int i, ret;

        if (atomic_inc_return(&cluster_usage[cluster]) != 1)
                return 0;

        if (cluster < MAX_CLUSTERS) {
                ret = _get_cluster_clk_and_freq_table(cpu_dev, cpumask);
                if (ret)
                        atomic_dec(&cluster_usage[cluster]);
                return ret;
        }

        /*
         * Get data for all clusters and fill virtual cluster with a merge of
         * both
         */
        for_each_present_cpu(i) {
                struct device *cdev = get_cpu_device(i);

                if (!cdev)
                        return -ENODEV;

                ret = _get_cluster_clk_and_freq_table(cdev, cpumask);
                if (ret)
                        goto put_clusters;
        }

        ret = merge_cluster_tables();
        if (ret)
                goto put_clusters;

        /* Assuming 2 cluster, set clk_big_min and clk_little_max */
        clk_big_min = get_table_min(freq_table[A15_CLUSTER]);
        clk_little_max = VIRT_FREQ(A7_CLUSTER,
                                   get_table_max(freq_table[A7_CLUSTER]));

        return 0;

put_clusters:
        for_each_present_cpu(i) {
                struct device *cdev = get_cpu_device(i);

                if (!cdev)
                        return -ENODEV;

                _put_cluster_clk_and_freq_table(cdev, cpumask);
        }

        atomic_dec(&cluster_usage[cluster]);

        return ret;
}

/* Per-CPU initialization */
static int ve_spc_cpufreq_init(struct cpufreq_policy *policy)
{
        u32 cur_cluster = cpu_to_cluster(policy->cpu);
        struct device *cpu_dev;
        int ret;

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

        if (cur_cluster < MAX_CLUSTERS) {
                int cpu;

                dev_pm_opp_get_sharing_cpus(cpu_dev, policy->cpus);

                for_each_cpu(cpu, policy->cpus)
                        per_cpu(physical_cluster, cpu) = cur_cluster;
        } else {
                /* Assumption: during init, we are always running on A15 */
                per_cpu(physical_cluster, policy->cpu) = A15_CLUSTER;
        }

        ret = get_cluster_clk_and_freq_table(cpu_dev, policy->cpus);
        if (ret)
                return ret;

        policy->freq_table = freq_table[cur_cluster];
        policy->cpuinfo.transition_latency = 1000000; /* 1 ms */

        dev_pm_opp_of_register_em(policy->cpus);

        if (is_bL_switching_enabled())
                per_cpu(cpu_last_req_freq, policy->cpu) =
                                                clk_get_cpu_rate(policy->cpu);

        dev_info(cpu_dev, "%s: CPU %d initialized\n", __func__, policy->cpu);
        return 0;
}

static int ve_spc_cpufreq_exit(struct cpufreq_policy *policy)
{
        struct device *cpu_dev;
        int cur_cluster = cpu_to_cluster(policy->cpu);

        if (cur_cluster < MAX_CLUSTERS) {
                cpufreq_cooling_unregister(cdev[cur_cluster]);
                cdev[cur_cluster] = NULL;
        }

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

        put_cluster_clk_and_freq_table(cpu_dev, policy->related_cpus);
        return 0;
}

static void ve_spc_cpufreq_ready(struct cpufreq_policy *policy)
{
        int cur_cluster = cpu_to_cluster(policy->cpu);

        /* Do not register a cpu_cooling device if we are in IKS mode */
        if (cur_cluster >= MAX_CLUSTERS)
                return;

        cdev[cur_cluster] = of_cpufreq_cooling_register(policy);
}

static struct cpufreq_driver ve_spc_cpufreq_driver = {
        .name                   = "vexpress-spc",
        .flags                  = CPUFREQ_STICKY |
                                        CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
                                        CPUFREQ_NEED_INITIAL_FREQ_CHECK,
        .verify                 = cpufreq_generic_frequency_table_verify,
        .target_index           = ve_spc_cpufreq_set_target,
        .get                    = ve_spc_cpufreq_get_rate,
        .init                   = ve_spc_cpufreq_init,
        .exit                   = ve_spc_cpufreq_exit,
        .ready                  = ve_spc_cpufreq_ready,
        .attr                   = cpufreq_generic_attr,
};

#ifdef CONFIG_BL_SWITCHER
static int bL_cpufreq_switcher_notifier(struct notifier_block *nfb,
                                        unsigned long action, void *_arg)
{
        pr_debug("%s: action: %ld\n", __func__, action);

        switch (action) {
        case BL_NOTIFY_PRE_ENABLE:
        case BL_NOTIFY_PRE_DISABLE:
                cpufreq_unregister_driver(&ve_spc_cpufreq_driver);
                break;

        case BL_NOTIFY_POST_ENABLE:
                set_switching_enabled(true);
                cpufreq_register_driver(&ve_spc_cpufreq_driver);
                break;

        case BL_NOTIFY_POST_DISABLE:
                set_switching_enabled(false);
                cpufreq_register_driver(&ve_spc_cpufreq_driver);
                break;

        default:
                return NOTIFY_DONE;
        }

        return NOTIFY_OK;
}

static struct notifier_block bL_switcher_notifier = {
        .notifier_call = bL_cpufreq_switcher_notifier,
};

static int __bLs_register_notifier(void)
{
        return bL_switcher_register_notifier(&bL_switcher_notifier);
}

static int __bLs_unregister_notifier(void)
{
        return bL_switcher_unregister_notifier(&bL_switcher_notifier);
}
#else
static int __bLs_register_notifier(void) { return 0; }
static int __bLs_unregister_notifier(void) { return 0; }
#endif

static int ve_spc_cpufreq_probe(struct platform_device *pdev)
{
        int ret, i;

        set_switching_enabled(bL_switcher_get_enabled());

        for (i = 0; i < MAX_CLUSTERS; i++)
                mutex_init(&cluster_lock[i]);

        ret = cpufreq_register_driver(&ve_spc_cpufreq_driver);
        if (ret) {
                pr_info("%s: Failed registering platform driver: %s, err: %d\n",
                        __func__, ve_spc_cpufreq_driver.name, ret);
        } else {
                ret = __bLs_register_notifier();
                if (ret)
                        cpufreq_unregister_driver(&ve_spc_cpufreq_driver);
                else
                        pr_info("%s: Registered platform driver: %s\n",
                                __func__, ve_spc_cpufreq_driver.name);
        }

        bL_switcher_put_enabled();
        return ret;
}

static int ve_spc_cpufreq_remove(struct platform_device *pdev)
{
        bL_switcher_get_enabled();
        __bLs_unregister_notifier();
        cpufreq_unregister_driver(&ve_spc_cpufreq_driver);
        bL_switcher_put_enabled();
        pr_info("%s: Un-registered platform driver: %s\n", __func__,
                ve_spc_cpufreq_driver.name);
        return 0;
}

static struct platform_driver ve_spc_cpufreq_platdrv = {
        .driver = {
                .name   = "vexpress-spc-cpufreq",
        },
        .probe          = ve_spc_cpufreq_probe,
        .remove         = ve_spc_cpufreq_remove,
};
module_platform_driver(ve_spc_cpufreq_platdrv);

MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
MODULE_DESCRIPTION("Vexpress SPC ARM big LITTLE cpufreq driver");
MODULE_LICENSE("GPL v2");