// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * pwm-fan.c - Hwmon driver for fans connected to PWM lines.
 *
 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
 *
 * Author: Kamil Debski <k.debski@samsung.com>
 */

#include <linux/delay.h>
#include <linux/hwmon.h>
#include <linux/interrupt.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/pwm.h>
#include <linux/regulator/consumer.h>
#include <linux/sysfs.h>
#include <linux/thermal.h>
#include <linux/timer.h>

#define MAX_PWM 255

struct pwm_fan_tach {
        int irq;
        atomic_t pulses;
        unsigned int rpm;
};

enum pwm_fan_enable_mode {
        pwm_off_reg_off,
        pwm_disable_reg_enable,
        pwm_enable_reg_enable,
        pwm_disable_reg_disable,
};

struct pwm_fan_ctx {
        struct device *dev;

        struct mutex lock;
        struct pwm_device *pwm;
        struct pwm_state pwm_state;
        struct regulator *reg_en;
        enum pwm_fan_enable_mode enable_mode;
        bool regulator_enabled;
        bool enabled;

        int tach_count;
        struct pwm_fan_tach *tachs;
        u32 *pulses_per_revolution;
        ktime_t sample_start;
        struct timer_list rpm_timer;

        unsigned int pwm_value;
        unsigned int pwm_fan_state;
        unsigned int pwm_fan_max_state;
        unsigned int *pwm_fan_cooling_levels;
        struct thermal_cooling_device *cdev;

        struct hwmon_chip_info info;
        struct hwmon_channel_info fan_channel;

        u64 pwm_duty_cycle_from_stopped;
        u32 pwm_usec_from_stopped;
        u8 pwm_shutdown;
};

/* This handler assumes self resetting edge triggered interrupt. */
static irqreturn_t pulse_handler(int irq, void *dev_id)
{
        struct pwm_fan_tach *tach = dev_id;

        atomic_inc(&tach->pulses);

        return IRQ_HANDLED;
}

static void sample_timer(struct timer_list *t)
{
        struct pwm_fan_ctx *ctx = timer_container_of(ctx, t, rpm_timer);
        unsigned int delta = ktime_ms_delta(ktime_get(), ctx->sample_start);
        int i;

        if (delta) {
                for (i = 0; i < ctx->tach_count; i++) {
                        struct pwm_fan_tach *tach = &ctx->tachs[i];
                        int pulses;

                        pulses = atomic_read(&tach->pulses);
                        atomic_sub(pulses, &tach->pulses);
                        tach->rpm = (unsigned int)(pulses * 1000 * 60) /
                                (ctx->pulses_per_revolution[i] * delta);
                }

                ctx->sample_start = ktime_get();
        }

        mod_timer(&ctx->rpm_timer, jiffies + HZ);
}

static void pwm_fan_enable_mode_2_state(int enable_mode,
                                        struct pwm_state *state,
                                        bool *enable_regulator)
{
        switch (enable_mode) {
        case pwm_disable_reg_enable:
                /* disable pwm, keep regulator enabled */
                state->enabled = false;
                *enable_regulator = true;
                break;
        case pwm_enable_reg_enable:
                /* keep pwm and regulator enabled */
                state->enabled = true;
                *enable_regulator = true;
                break;
        case pwm_off_reg_off:
        case pwm_disable_reg_disable:
                /* disable pwm and regulator */
                state->enabled = false;
                *enable_regulator = false;
        }
}

static int pwm_fan_switch_power(struct pwm_fan_ctx *ctx, bool on)
{
        int ret = 0;

        if (!ctx->reg_en)
                return ret;

        if (!ctx->regulator_enabled && on) {
                ret = regulator_enable(ctx->reg_en);
                if (ret == 0)
                        ctx->regulator_enabled = true;
        } else if (ctx->regulator_enabled && !on) {
                ret = regulator_disable(ctx->reg_en);
                if (ret == 0)
                        ctx->regulator_enabled = false;
        }
        return ret;
}

static int pwm_fan_power_on(struct pwm_fan_ctx *ctx)
{
        struct pwm_state *state = &ctx->pwm_state;
        int ret;

        if (ctx->enabled)
                return 0;

        ret = pwm_fan_switch_power(ctx, true);
        if (ret < 0) {
                dev_err(ctx->dev, "failed to enable power supply\n");
                return ret;
        }

        state->enabled = true;
        ret = pwm_apply_might_sleep(ctx->pwm, state);
        if (ret) {
                dev_err(ctx->dev, "failed to enable PWM\n");
                goto disable_regulator;
        }

        ctx->enabled = true;

        return 0;

disable_regulator:
        pwm_fan_switch_power(ctx, false);
        return ret;
}

static int pwm_fan_power_off(struct pwm_fan_ctx *ctx, bool force_disable)
{
        struct pwm_state *state = &ctx->pwm_state;
        bool enable_regulator = false;
        int ret;

        if (!ctx->enabled)
                return 0;

        pwm_fan_enable_mode_2_state(ctx->enable_mode,
                                    state,
                                    &enable_regulator);

        if (force_disable)
                state->enabled = false;
        state->duty_cycle = 0;
        ret = pwm_apply_might_sleep(ctx->pwm, state);
        if (ret) {
                dev_err(ctx->dev, "failed to disable PWM\n");
                return ret;
        }

        pwm_fan_switch_power(ctx, enable_regulator);

        ctx->enabled = false;

        return 0;
}

static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
{
        struct pwm_state *state = &ctx->pwm_state;
        unsigned long final_pwm = pwm;
        unsigned long period;
        bool update = false;
        int ret = 0;

        if (pwm > 0) {
                if (ctx->enable_mode == pwm_off_reg_off)
                        /* pwm-fan hard disabled */
                        return 0;

                period = state->period;
                update = state->duty_cycle < ctx->pwm_duty_cycle_from_stopped;
                if (update)
                        state->duty_cycle = ctx->pwm_duty_cycle_from_stopped;
                else
                        state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
                ret = pwm_apply_might_sleep(ctx->pwm, state);
                if (ret)
                        return ret;
                ret = pwm_fan_power_on(ctx);
                if (!ret && update) {
                        pwm = final_pwm;
                        state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
                        usleep_range(ctx->pwm_usec_from_stopped,
                                     ctx->pwm_usec_from_stopped * 2);
                        ret = pwm_apply_might_sleep(ctx->pwm, state);
                }
        } else {
                ret = pwm_fan_power_off(ctx, false);
        }
        if (!ret)
                ctx->pwm_value = pwm;

        return ret;
}

static int set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
{
        int ret;

        mutex_lock(&ctx->lock);
        ret = __set_pwm(ctx, pwm);
        mutex_unlock(&ctx->lock);

        return ret;
}

static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
{
        int i;

        for (i = 0; i < ctx->pwm_fan_max_state; ++i)
                if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
                        break;

        ctx->pwm_fan_state = i;
}

static int pwm_fan_update_enable(struct pwm_fan_ctx *ctx, long val)
{
        int ret = 0;
        int old_val;

        mutex_lock(&ctx->lock);

        if (ctx->enable_mode == val)
                goto out;

        old_val = ctx->enable_mode;
        ctx->enable_mode = val;

        if (val == 0) {
                /* Disable pwm-fan unconditionally */
                if (ctx->enabled)
                        ret = __set_pwm(ctx, 0);
                else
                        ret = pwm_fan_switch_power(ctx, false);
                if (ret)
                        ctx->enable_mode = old_val;
                pwm_fan_update_state(ctx, 0);
        } else {
                /*
                 * Change PWM and/or regulator state if currently disabled
                 * Nothing to do if currently enabled
                 */
                if (!ctx->enabled) {
                        struct pwm_state *state = &ctx->pwm_state;
                        bool enable_regulator = false;

                        state->duty_cycle = 0;
                        pwm_fan_enable_mode_2_state(val,
                                                    state,
                                                    &enable_regulator);

                        pwm_apply_might_sleep(ctx->pwm, state);
                        pwm_fan_switch_power(ctx, enable_regulator);
                        pwm_fan_update_state(ctx, 0);
                }
        }
out:
        mutex_unlock(&ctx->lock);

        return ret;
}

static int pwm_fan_write(struct device *dev, enum hwmon_sensor_types type,
                         u32 attr, int channel, long val)
{
        struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
        int ret;

        switch (attr) {
        case hwmon_pwm_input:
                if (val < 0 || val > MAX_PWM)
                        return -EINVAL;
                ret = set_pwm(ctx, val);
                if (ret)
                        return ret;
                pwm_fan_update_state(ctx, val);
                break;
        case hwmon_pwm_enable:
                if (val < 0 || val > 3)
                        ret = -EINVAL;
                else
                        ret = pwm_fan_update_enable(ctx, val);

                return ret;
        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static int pwm_fan_read(struct device *dev, enum hwmon_sensor_types type,
                        u32 attr, int channel, long *val)
{
        struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);

        switch (type) {
        case hwmon_pwm:
                switch (attr) {
                case hwmon_pwm_input:
                        *val = ctx->pwm_value;
                        return 0;
                case hwmon_pwm_enable:
                        *val = ctx->enable_mode;
                        return 0;
                }
                return -EOPNOTSUPP;
        case hwmon_fan:
                *val = ctx->tachs[channel].rpm;
                return 0;

        default:
                return -ENOTSUPP;
        }
}

static umode_t pwm_fan_is_visible(const void *data,
                                  enum hwmon_sensor_types type,
                                  u32 attr, int channel)
{
        switch (type) {
        case hwmon_pwm:
                return 0644;

        case hwmon_fan:
                return 0444;

        default:
                return 0;
        }
}

static const struct hwmon_ops pwm_fan_hwmon_ops = {
        .is_visible = pwm_fan_is_visible,
        .read = pwm_fan_read,
        .write = pwm_fan_write,
};

/* thermal cooling device callbacks */
static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
                                 unsigned long *state)
{
        struct pwm_fan_ctx *ctx = cdev->devdata;

        if (!ctx)
                return -EINVAL;

        *state = ctx->pwm_fan_max_state;

        return 0;
}

static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
                                 unsigned long *state)
{
        struct pwm_fan_ctx *ctx = cdev->devdata;

        if (!ctx)
                return -EINVAL;

        *state = ctx->pwm_fan_state;

        return 0;
}

static int
pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
{
        struct pwm_fan_ctx *ctx = cdev->devdata;
        int ret;

        if (!ctx || (state > ctx->pwm_fan_max_state))
                return -EINVAL;

        if (state == ctx->pwm_fan_state)
                return 0;

        ret = set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
        if (ret) {
                dev_err(&cdev->device, "Cannot set pwm!\n");
                return ret;
        }

        ctx->pwm_fan_state = state;

        return ret;
}

static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
        .get_max_state = pwm_fan_get_max_state,
        .get_cur_state = pwm_fan_get_cur_state,
        .set_cur_state = pwm_fan_set_cur_state,
};

static int pwm_fan_get_cooling_data(struct device *dev, struct pwm_fan_ctx *ctx)
{
        int num, i, ret;

        if (!device_property_present(dev, "cooling-levels"))
                return 0;

        ret = device_property_count_u32(dev, "cooling-levels");
        if (ret <= 0) {
                dev_err(dev, "Wrong data!\n");
                return ret ? : -EINVAL;
        }

        num = ret;
        ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
                                                   GFP_KERNEL);
        if (!ctx->pwm_fan_cooling_levels)
                return -ENOMEM;

        ret = device_property_read_u32_array(dev, "cooling-levels",
                                             ctx->pwm_fan_cooling_levels, num);
        if (ret) {
                dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
                return ret;
        }

        for (i = 0; i < num; i++) {
                if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
                        dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
                                ctx->pwm_fan_cooling_levels[i], MAX_PWM);
                        return -EINVAL;
                }
        }

        ctx->pwm_fan_max_state = num - 1;

        return 0;
}

static void pwm_fan_cleanup(void *__ctx)
{
        struct pwm_fan_ctx *ctx = __ctx;

        timer_delete_sync(&ctx->rpm_timer);
        if (ctx->pwm_shutdown) {
                ctx->enable_mode = pwm_enable_reg_enable;
                __set_pwm(ctx, ctx->pwm_shutdown);
        } else {
                /* Switch off everything */
                ctx->enable_mode = pwm_disable_reg_disable;
                pwm_fan_power_off(ctx, true);
        }
}

static int pwm_fan_probe(struct platform_device *pdev)
{
        struct thermal_cooling_device *cdev;
        struct device *dev = &pdev->dev;
        struct pwm_fan_ctx *ctx;
        struct device *hwmon;
        int ret;
        const struct hwmon_channel_info **channels;
        u32 initial_pwm, pwm_min_from_stopped = 0;
        u32 pwm_shutdown_percent = 0;
        u32 *fan_channel_config;
        int channel_count = 1;  /* We always have a PWM channel. */
        int i;

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

        mutex_init(&ctx->lock);

        ctx->dev = &pdev->dev;
        ctx->pwm = devm_pwm_get(dev, NULL);
        if (IS_ERR(ctx->pwm))
                return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n");

        platform_set_drvdata(pdev, ctx);

        ctx->reg_en = devm_regulator_get_optional(dev, "fan");
        if (IS_ERR(ctx->reg_en)) {
                if (PTR_ERR(ctx->reg_en) != -ENODEV)
                        return PTR_ERR(ctx->reg_en);

                ctx->reg_en = NULL;
        }

        pwm_init_state(ctx->pwm, &ctx->pwm_state);

        /*
         * PWM fans are controlled solely by the duty cycle of the PWM signal,
         * they do not care about the exact timing. Thus set usage_power to true
         * to allow less flexible hardware to work as a PWM source for fan
         * control.
         */
        ctx->pwm_state.usage_power = true;

        /*
         * set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned
         * long. Check this here to prevent the fan running at a too low
         * frequency.
         */
        if (ctx->pwm_state.period > ULONG_MAX / MAX_PWM + 1) {
                dev_err(dev, "Configured period too big\n");
                return -EINVAL;
        }

        ctx->enable_mode = pwm_disable_reg_enable;

        ret = pwm_fan_get_cooling_data(dev, ctx);
        if (ret)
                return ret;

        /* use maximum cooling level if provided */
        if (ctx->pwm_fan_cooling_levels)
                initial_pwm = ctx->pwm_fan_cooling_levels[ctx->pwm_fan_max_state];
        else
                initial_pwm = MAX_PWM;

        /*
         * Set duty cycle to maximum allowed and enable PWM output as well as
         * the regulator. In case of error nothing is changed
         */
        ret = set_pwm(ctx, initial_pwm);
        if (ret) {
                dev_err(dev, "Failed to configure PWM: %d\n", ret);
                return ret;
        }
        timer_setup(&ctx->rpm_timer, sample_timer, 0);
        ret = devm_add_action_or_reset(dev, pwm_fan_cleanup, ctx);
        if (ret)
                return ret;

        ctx->tach_count = platform_irq_count(pdev);
        if (ctx->tach_count < 0)
                return dev_err_probe(dev, ctx->tach_count,
                                     "Could not get number of fan tachometer inputs\n");
        dev_dbg(dev, "%d fan tachometer inputs\n", ctx->tach_count);

        if (ctx->tach_count) {
                channel_count++;        /* We also have a FAN channel. */

                ctx->tachs = devm_kcalloc(dev, ctx->tach_count,
                                          sizeof(struct pwm_fan_tach),
                                          GFP_KERNEL);
                if (!ctx->tachs)
                        return -ENOMEM;

                ctx->fan_channel.type = hwmon_fan;
                fan_channel_config = devm_kcalloc(dev, ctx->tach_count + 1,
                                                  sizeof(u32), GFP_KERNEL);
                if (!fan_channel_config)
                        return -ENOMEM;
                ctx->fan_channel.config = fan_channel_config;

                ctx->pulses_per_revolution = devm_kmalloc_array(dev,
                                                                ctx->tach_count,
                                                                sizeof(*ctx->pulses_per_revolution),
                                                                GFP_KERNEL);
                if (!ctx->pulses_per_revolution)
                        return -ENOMEM;

                /* Setup default pulses per revolution */
                for (i = 0; i < ctx->tach_count; i++)
                        ctx->pulses_per_revolution[i] = 2;

                device_property_read_u32_array(dev, "pulses-per-revolution",
                                               ctx->pulses_per_revolution, ctx->tach_count);
        }

        channels = devm_kcalloc(dev, channel_count + 1,
                                sizeof(struct hwmon_channel_info *), GFP_KERNEL);
        if (!channels)
                return -ENOMEM;

        channels[0] = HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT | HWMON_PWM_ENABLE);

        for (i = 0; i < ctx->tach_count; i++) {
                struct pwm_fan_tach *tach = &ctx->tachs[i];

                tach->irq = platform_get_irq(pdev, i);
                if (tach->irq == -EPROBE_DEFER)
                        return tach->irq;
                if (tach->irq > 0) {
                        ret = devm_request_irq(dev, tach->irq, pulse_handler,
                                               IRQF_NO_THREAD, pdev->name, tach);
                        if (ret) {
                                dev_err(dev,
                                        "Failed to request interrupt: %d\n",
                                        ret);
                                return ret;
                        }
                }

                if (!ctx->pulses_per_revolution[i]) {
                        dev_err(dev, "pulses-per-revolution can't be zero.\n");
                        return -EINVAL;
                }

                fan_channel_config[i] = HWMON_F_INPUT;

                dev_dbg(dev, "tach%d: irq=%d, pulses_per_revolution=%d\n",
                        i, tach->irq, ctx->pulses_per_revolution[i]);
        }

        if (ctx->tach_count > 0) {
                ctx->sample_start = ktime_get();
                mod_timer(&ctx->rpm_timer, jiffies + HZ);

                channels[1] = &ctx->fan_channel;
        }

        ret = device_property_read_u32(dev, "fan-shutdown-percent",
                                       &pwm_shutdown_percent);
        if (!ret && pwm_shutdown_percent)
                ctx->pwm_shutdown = (clamp(pwm_shutdown_percent, 0, 100) * 255) / 100;

        ret = device_property_read_u32(dev, "fan-stop-to-start-percent",
                                       &pwm_min_from_stopped);
        if (!ret && pwm_min_from_stopped) {
                ctx->pwm_duty_cycle_from_stopped =
                        DIV_ROUND_UP_ULL(pwm_min_from_stopped *
                                         (ctx->pwm_state.period - 1),
                                         100);
        }
        ret = device_property_read_u32(dev, "fan-stop-to-start-us",
                                       &ctx->pwm_usec_from_stopped);
        if (ret)
                ctx->pwm_usec_from_stopped = 250000;

        ctx->info.ops = &pwm_fan_hwmon_ops;
        ctx->info.info = channels;

        hwmon = devm_hwmon_device_register_with_info(dev, "pwmfan",
                                                     ctx, &ctx->info, NULL);
        if (IS_ERR(hwmon)) {
                dev_err(dev, "Failed to register hwmon device\n");
                return PTR_ERR(hwmon);
        }

        ctx->pwm_fan_state = ctx->pwm_fan_max_state;
        if (IS_ENABLED(CONFIG_THERMAL)) {
                cdev = devm_thermal_of_cooling_device_register(dev,
                        dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
                if (IS_ERR(cdev)) {
                        ret = PTR_ERR(cdev);
                        dev_err(dev,
                                "Failed to register pwm-fan as cooling device: %d\n",
                                ret);
                        return ret;
                }
                ctx->cdev = cdev;
        }

        return 0;
}

static void pwm_fan_shutdown(struct platform_device *pdev)
{
        struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);

        pwm_fan_cleanup(ctx);
}

static int pwm_fan_suspend(struct device *dev)
{
        struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);

        return pwm_fan_power_off(ctx, true);
}

static int pwm_fan_resume(struct device *dev)
{
        struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);

        return set_pwm(ctx, ctx->pwm_value);
}

static DEFINE_SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);

static const struct of_device_id of_pwm_fan_match[] = {
        { .compatible = "pwm-fan", },
        {},
};
MODULE_DEVICE_TABLE(of, of_pwm_fan_match);

static struct platform_driver pwm_fan_driver = {
        .probe          = pwm_fan_probe,
        .shutdown       = pwm_fan_shutdown,
        .driver = {
                .name           = "pwm-fan",
                .pm             = pm_sleep_ptr(&pwm_fan_pm),
                .of_match_table = of_pwm_fan_match,
        },
};

module_platform_driver(pwm_fan_driver);

MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
MODULE_ALIAS("platform:pwm-fan");
MODULE_DESCRIPTION("PWM FAN driver");
MODULE_LICENSE("GPL");