// SPDX-License-Identifier: GPL-2.0-only
/*
 * CPUFreq driver for the Loongson-3 processors.
 *
 * All revisions of Loongson-3 processor support cpu_has_scalefreq feature.
 *
 * Author: Huacai Chen <chenhuacai@loongson.cn>
 * Copyright (C) 2024 Loongson Technology Corporation Limited
 */
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/units.h>

#include <asm/idle.h>
#include <asm/loongarch.h>
#include <asm/loongson.h>

/* Message */
union smc_message {
        u32 value;
        struct {
                u32 id          : 4;
                u32 info        : 4;
                u32 val         : 16;
                u32 cmd         : 6;
                u32 extra       : 1;
                u32 complete    : 1;
        };
};

/* Command return values */
#define CMD_OK                          0 /* No error */
#define CMD_ERROR                       1 /* Regular error */
#define CMD_NOCMD                       2 /* Command does not support */
#define CMD_INVAL                       3 /* Invalid Parameter */

/* Version commands */
/*
 * CMD_GET_VERSION - Get interface version
 * Input: none
 * Output: version
 */
#define CMD_GET_VERSION                 0x1

/* Feature commands */
/*
 * CMD_GET_FEATURE - Get feature state
 * Input: feature ID
 * Output: feature flag
 */
#define CMD_GET_FEATURE                 0x2

/*
 * CMD_SET_FEATURE - Set feature state
 * Input: feature ID, feature flag
 * output: none
 */
#define CMD_SET_FEATURE                 0x3

/* Feature IDs */
#define FEATURE_SENSOR                  0
#define FEATURE_FAN                     1
#define FEATURE_DVFS                    2

/* Sensor feature flags */
#define FEATURE_SENSOR_ENABLE           BIT(0)
#define FEATURE_SENSOR_SAMPLE           BIT(1)

/* Fan feature flags */
#define FEATURE_FAN_ENABLE              BIT(0)
#define FEATURE_FAN_AUTO                BIT(1)

/* DVFS feature flags */
#define FEATURE_DVFS_ENABLE             BIT(0)
#define FEATURE_DVFS_BOOST              BIT(1)
#define FEATURE_DVFS_AUTO               BIT(2)
#define FEATURE_DVFS_SINGLE_BOOST       BIT(3)

/* Sensor commands */
/*
 * CMD_GET_SENSOR_NUM - Get number of sensors
 * Input: none
 * Output: number
 */
#define CMD_GET_SENSOR_NUM              0x4

/*
 * CMD_GET_SENSOR_STATUS - Get sensor status
 * Input: sensor ID, type
 * Output: sensor status
 */
#define CMD_GET_SENSOR_STATUS           0x5

/* Sensor types */
#define SENSOR_INFO_TYPE                0
#define SENSOR_INFO_TYPE_TEMP           1

/* Fan commands */
/*
 * CMD_GET_FAN_NUM - Get number of fans
 * Input: none
 * Output: number
 */
#define CMD_GET_FAN_NUM                 0x6

/*
 * CMD_GET_FAN_INFO - Get fan status
 * Input: fan ID, type
 * Output: fan info
 */
#define CMD_GET_FAN_INFO                0x7

/*
 * CMD_SET_FAN_INFO - Set fan status
 * Input: fan ID, type, value
 * Output: none
 */
#define CMD_SET_FAN_INFO                0x8

/* Fan types */
#define FAN_INFO_TYPE_LEVEL             0

/* DVFS commands */
/*
 * CMD_GET_FREQ_LEVEL_NUM - Get number of freq levels
 * Input: CPU ID
 * Output: number
 */
#define CMD_GET_FREQ_LEVEL_NUM          0x9

/*
 * CMD_GET_FREQ_BOOST_LEVEL - Get the first boost level
 * Input: CPU ID
 * Output: number
 */
#define CMD_GET_FREQ_BOOST_LEVEL        0x10

/*
 * CMD_GET_FREQ_LEVEL_INFO - Get freq level info
 * Input: CPU ID, level ID
 * Output: level info
 */
#define CMD_GET_FREQ_LEVEL_INFO         0x11

/*
 * CMD_GET_FREQ_INFO - Get freq info
 * Input: CPU ID, type
 * Output: freq info
 */
#define CMD_GET_FREQ_INFO               0x12

/*
 * CMD_SET_FREQ_INFO - Set freq info
 * Input: CPU ID, type, value
 * Output: none
 */
#define CMD_SET_FREQ_INFO               0x13

/* Freq types */
#define FREQ_INFO_TYPE_FREQ             0
#define FREQ_INFO_TYPE_LEVEL            1

#define FREQ_MAX_LEVEL                  16

struct loongson3_freq_data {
        unsigned int def_freq_level;
        struct cpufreq_frequency_table table[];
};

static struct mutex cpufreq_mutex[MAX_PACKAGES];
static struct cpufreq_driver loongson3_cpufreq_driver;
static DEFINE_PER_CPU(struct loongson3_freq_data *, freq_data);

static inline int do_service_request(u32 id, u32 info, u32 cmd, u32 val, u32 extra)
{
        int retries;
        unsigned int cpu = raw_smp_processor_id();
        unsigned int package = cpu_data[cpu].package;
        union smc_message msg, last;

        mutex_lock(&cpufreq_mutex[package]);

        last.value = iocsr_read32(LOONGARCH_IOCSR_SMCMBX);
        if (!last.complete) {
                mutex_unlock(&cpufreq_mutex[package]);
                return -EPERM;
        }

        msg.id          = id;
        msg.info        = info;
        msg.cmd         = cmd;
        msg.val         = val;
        msg.extra       = extra;
        msg.complete    = 0;

        iocsr_write32(msg.value, LOONGARCH_IOCSR_SMCMBX);
        iocsr_write32(iocsr_read32(LOONGARCH_IOCSR_MISC_FUNC) | IOCSR_MISC_FUNC_SOFT_INT,
                      LOONGARCH_IOCSR_MISC_FUNC);

        for (retries = 0; retries < 10000; retries++) {
                msg.value = iocsr_read32(LOONGARCH_IOCSR_SMCMBX);
                if (msg.complete)
                        break;

                usleep_range(8, 12);
        }

        if (!msg.complete || msg.cmd != CMD_OK) {
                mutex_unlock(&cpufreq_mutex[package]);
                return -EPERM;
        }

        mutex_unlock(&cpufreq_mutex[package]);

        return msg.val;
}

static unsigned int loongson3_cpufreq_get(unsigned int cpu)
{
        int ret;

        ret = do_service_request(cpu, FREQ_INFO_TYPE_FREQ, CMD_GET_FREQ_INFO, 0, 0);

        return ret * KILO;
}

static int loongson3_cpufreq_target(struct cpufreq_policy *policy, unsigned int index)
{
        int ret;

        ret = do_service_request(cpu_data[policy->cpu].core,
                                 FREQ_INFO_TYPE_LEVEL, CMD_SET_FREQ_INFO, index, 0);

        return (ret >= 0) ? 0 : ret;
}

static int configure_freq_table(int cpu)
{
        int i, ret, boost_level, max_level, freq_level;
        struct platform_device *pdev = cpufreq_get_driver_data();
        struct loongson3_freq_data *data;

        if (per_cpu(freq_data, cpu))
                return 0;

        ret = do_service_request(cpu, 0, CMD_GET_FREQ_LEVEL_NUM, 0, 0);
        if (ret < 0)
                return ret;
        max_level = ret;

        ret = do_service_request(cpu, 0, CMD_GET_FREQ_BOOST_LEVEL, 0, 0);
        if (ret < 0)
                return ret;
        boost_level = ret;

        freq_level = min(max_level, FREQ_MAX_LEVEL);
        data = devm_kzalloc(&pdev->dev, struct_size(data, table, freq_level + 1), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->def_freq_level = boost_level - 1;

        for (i = 0; i < freq_level; i++) {
                ret = do_service_request(cpu, FREQ_INFO_TYPE_FREQ, CMD_GET_FREQ_LEVEL_INFO, i, 0);
                if (ret < 0) {
                        devm_kfree(&pdev->dev, data);
                        return ret;
                }

                data->table[i].frequency = ret * KILO;
                data->table[i].flags = (i >= boost_level) ? CPUFREQ_BOOST_FREQ : 0;
        }

        data->table[freq_level].flags = 0;
        data->table[freq_level].frequency = CPUFREQ_TABLE_END;

        per_cpu(freq_data, cpu) = data;

        return 0;
}

static int loongson3_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
        int i, ret, cpu = policy->cpu;

        ret = configure_freq_table(cpu);
        if (ret < 0)
                return ret;

        policy->cpuinfo.transition_latency = 10000;
        policy->freq_table = per_cpu(freq_data, cpu)->table;
        policy->suspend_freq = policy->freq_table[per_cpu(freq_data, cpu)->def_freq_level].frequency;
        cpumask_copy(policy->cpus, topology_sibling_cpumask(cpu));

        for_each_cpu(i, policy->cpus) {
                if (i != cpu)
                        per_cpu(freq_data, i) = per_cpu(freq_data, cpu);
        }

        return 0;
}

static void loongson3_cpufreq_cpu_exit(struct cpufreq_policy *policy)
{
        int cpu = policy->cpu;

        loongson3_cpufreq_target(policy, per_cpu(freq_data, cpu)->def_freq_level);
}

static int loongson3_cpufreq_cpu_online(struct cpufreq_policy *policy)
{
        return 0;
}

static int loongson3_cpufreq_cpu_offline(struct cpufreq_policy *policy)
{
        return 0;
}

static struct cpufreq_driver loongson3_cpufreq_driver = {
        .name = "loongson3",
        .flags = CPUFREQ_CONST_LOOPS,
        .init = loongson3_cpufreq_cpu_init,
        .exit = loongson3_cpufreq_cpu_exit,
        .online = loongson3_cpufreq_cpu_online,
        .offline = loongson3_cpufreq_cpu_offline,
        .get = loongson3_cpufreq_get,
        .target_index = loongson3_cpufreq_target,
        .verify = cpufreq_generic_frequency_table_verify,
        .set_boost = cpufreq_boost_set_sw,
        .suspend = cpufreq_generic_suspend,
};

static int loongson3_cpufreq_probe(struct platform_device *pdev)
{
        int i, ret;

        for (i = 0; i < MAX_PACKAGES; i++) {
                ret = devm_mutex_init(&pdev->dev, &cpufreq_mutex[i]);
                if (ret)
                        return ret;
        }

        ret = do_service_request(0, 0, CMD_GET_VERSION, 0, 0);
        if (ret <= 0)
                return -EPERM;

        ret = do_service_request(FEATURE_DVFS, 0, CMD_SET_FEATURE,
                                 FEATURE_DVFS_ENABLE | FEATURE_DVFS_BOOST, 0);
        if (ret < 0)
                return -EPERM;

        loongson3_cpufreq_driver.driver_data = pdev;

        ret = cpufreq_register_driver(&loongson3_cpufreq_driver);
        if (ret)
                return ret;

        pr_info("cpufreq: Loongson-3 CPU frequency driver.\n");

        return 0;
}

static void loongson3_cpufreq_remove(struct platform_device *pdev)
{
        cpufreq_unregister_driver(&loongson3_cpufreq_driver);
}

static struct platform_device_id cpufreq_id_table[] = {
        { "loongson3_cpufreq", },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(platform, cpufreq_id_table);

static struct platform_driver loongson3_platform_driver = {
        .driver = {
                .name = "loongson3_cpufreq",
        },
        .id_table = cpufreq_id_table,
        .probe = loongson3_cpufreq_probe,
        .remove = loongson3_cpufreq_remove,
};
module_platform_driver(loongson3_platform_driver);

MODULE_AUTHOR("Huacai Chen <chenhuacai@loongson.cn>");
MODULE_DESCRIPTION("CPUFreq driver for Loongson-3 processors");
MODULE_LICENSE("GPL");