// SPDX-License-Identifier: GPL-2.0+
/*
 * CPUFreq support for Armada 8K
 *
 * Copyright (C) 2018 Marvell
 *
 * Omri Itach <omrii@marvell.com>
 * Gregory Clement <gregory.clement@bootlin.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/clk.h>
#include <linux/cpu.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_opp.h>
#include <linux/slab.h>

/*
 * Setup the opps list with the divider for the max frequency, that
 * will be filled at runtime.
 */
static const int opps_div[] __initconst = {1, 2, 3, 4};

static struct platform_device *armada_8k_pdev;

struct freq_table {
        struct device *cpu_dev;
        unsigned int freq[ARRAY_SIZE(opps_div)];
};

/* If the CPUs share the same clock, then they are in the same cluster. */
static void __init armada_8k_get_sharing_cpus(struct clk *cur_clk,
                                              struct cpumask *cpumask)
{
        int cpu;

        for_each_possible_cpu(cpu) {
                struct device *cpu_dev;
                struct clk *clk;

                cpu_dev = get_cpu_device(cpu);
                if (!cpu_dev) {
                        pr_warn("Failed to get cpu%d device\n", cpu);
                        continue;
                }

                clk = clk_get(cpu_dev, 0);
                if (IS_ERR(clk)) {
                        pr_warn("Cannot get clock for CPU %d\n", cpu);
                } else {
                        if (clk_is_match(clk, cur_clk))
                                cpumask_set_cpu(cpu, cpumask);

                        clk_put(clk);
                }
        }
}

static int __init armada_8k_add_opp(struct clk *clk, struct device *cpu_dev,
                                    struct freq_table *freq_tables,
                                    int opps_index)
{
        unsigned int cur_frequency;
        unsigned int freq;
        int i, ret;

        /* Get nominal (current) CPU frequency. */
        cur_frequency = clk_get_rate(clk);
        if (!cur_frequency) {
                dev_err(cpu_dev, "Failed to get clock rate for this CPU\n");
                return -EINVAL;
        }

        freq_tables[opps_index].cpu_dev = cpu_dev;

        for (i = 0; i < ARRAY_SIZE(opps_div); i++) {
                freq = cur_frequency / opps_div[i];

                ret = dev_pm_opp_add(cpu_dev, freq, 0);
                if (ret)
                        return ret;

                freq_tables[opps_index].freq[i] = freq;
        }

        return 0;
}

static void armada_8k_cpufreq_free_table(struct freq_table *freq_tables)
{
        int opps_index, nb_cpus = num_possible_cpus();

        for (opps_index = 0 ; opps_index <= nb_cpus; opps_index++) {
                int i;

                /* If cpu_dev is NULL then we reached the end of the array */
                if (!freq_tables[opps_index].cpu_dev)
                        break;

                for (i = 0; i < ARRAY_SIZE(opps_div); i++) {
                        /*
                         * A 0Hz frequency is not valid, this meant
                         * that it was not yet initialized so there is
                         * no more opp to free
                         */
                        if (freq_tables[opps_index].freq[i] == 0)
                                break;

                        dev_pm_opp_remove(freq_tables[opps_index].cpu_dev,
                                          freq_tables[opps_index].freq[i]);
                }
        }

        kfree(freq_tables);
}

static int __init armada_8k_cpufreq_init(void)
{
        int ret = 0, opps_index = 0, cpu, nb_cpus;
        struct freq_table *freq_tables;
        struct device_node *node;
        struct cpumask cpus;

        node = of_find_compatible_node(NULL, NULL, "marvell,ap806-cpu-clock");
        if (!node || !of_device_is_available(node)) {
                of_node_put(node);
                return -ENODEV;
        }
        of_node_put(node);

        nb_cpus = num_possible_cpus();
        freq_tables = kcalloc(nb_cpus, sizeof(*freq_tables), GFP_KERNEL);
        if (!freq_tables)
                return -ENOMEM;
        cpumask_copy(&cpus, cpu_possible_mask);

        /*
         * For each CPU, this loop registers the operating points
         * supported (which are the nominal CPU frequency and full integer
         * divisions of it).
         */
        for_each_cpu(cpu, &cpus) {
                struct cpumask shared_cpus;
                struct device *cpu_dev;
                struct clk *clk;

                cpu_dev = get_cpu_device(cpu);

                if (!cpu_dev) {
                        pr_err("Cannot get CPU %d\n", cpu);
                        continue;
                }

                clk = clk_get(cpu_dev, 0);

                if (IS_ERR(clk)) {
                        pr_err("Cannot get clock for CPU %d\n", cpu);
                        ret = PTR_ERR(clk);
                        goto remove_opp;
                }

                ret = armada_8k_add_opp(clk, cpu_dev, freq_tables, opps_index);
                if (ret) {
                        clk_put(clk);
                        goto remove_opp;
                }

                opps_index++;
                cpumask_clear(&shared_cpus);
                armada_8k_get_sharing_cpus(clk, &shared_cpus);
                dev_pm_opp_set_sharing_cpus(cpu_dev, &shared_cpus);
                cpumask_andnot(&cpus, &cpus, &shared_cpus);
                clk_put(clk);
        }

        armada_8k_pdev = platform_device_register_simple("cpufreq-dt", -1,
                                                         NULL, 0);
        ret = PTR_ERR_OR_ZERO(armada_8k_pdev);
        if (ret)
                goto remove_opp;

        platform_set_drvdata(armada_8k_pdev, freq_tables);

        return 0;

remove_opp:
        armada_8k_cpufreq_free_table(freq_tables);
        return ret;
}
module_init(armada_8k_cpufreq_init);

static void __exit armada_8k_cpufreq_exit(void)
{
        struct freq_table *freq_tables = platform_get_drvdata(armada_8k_pdev);

        platform_device_unregister(armada_8k_pdev);
        armada_8k_cpufreq_free_table(freq_tables);
}
module_exit(armada_8k_cpufreq_exit);

MODULE_AUTHOR("Gregory Clement <gregory.clement@bootlin.com>");
MODULE_DESCRIPTION("Armada 8K cpufreq driver");
MODULE_LICENSE("GPL");