// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * gpio-fan.c - Hwmon driver for fans connected to GPIO lines.
 *
 * Copyright (C) 2010 LaCie
 *
 * Author: Simon Guinot <sguinot@lacie.com>
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/hwmon.h>
#include <linux/gpio/consumer.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/thermal.h>

struct gpio_fan_speed {
        int rpm;
        int ctrl_val;
};

struct gpio_fan_data {
        struct device           *dev;
        struct device           *hwmon_dev;
        /* Cooling device if any */
        struct thermal_cooling_device *cdev;
        struct mutex            lock; /* lock GPIOs operations. */
        int                     num_gpios;
        struct gpio_desc        **gpios;
        int                     num_speed;
        struct gpio_fan_speed   *speed;
        int                     speed_index;
#ifdef CONFIG_PM_SLEEP
        int                     resume_speed;
#endif
        bool                    pwm_enable;
        struct gpio_desc        *alarm_gpio;
        struct work_struct      alarm_work;
};

/*
 * Alarm GPIO.
 */

static void fan_alarm_notify(struct work_struct *ws)
{
        struct gpio_fan_data *fan_data =
                container_of(ws, struct gpio_fan_data, alarm_work);

        sysfs_notify(&fan_data->hwmon_dev->kobj, NULL, "fan1_alarm");
        kobject_uevent(&fan_data->hwmon_dev->kobj, KOBJ_CHANGE);
}

static irqreturn_t fan_alarm_irq_handler(int irq, void *dev_id)
{
        struct gpio_fan_data *fan_data = dev_id;

        schedule_work(&fan_data->alarm_work);

        return IRQ_NONE;
}

static ssize_t fan1_alarm_show(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

        return sprintf(buf, "%d\n",
                       gpiod_get_value_cansleep(fan_data->alarm_gpio));
}

static DEVICE_ATTR_RO(fan1_alarm);

static int fan_alarm_init(struct gpio_fan_data *fan_data)
{
        int alarm_irq;
        struct device *dev = fan_data->dev;

        /*
         * If the alarm GPIO don't support interrupts, just leave
         * without initializing the fail notification support.
         */
        alarm_irq = gpiod_to_irq(fan_data->alarm_gpio);
        if (alarm_irq <= 0)
                return 0;

        INIT_WORK(&fan_data->alarm_work, fan_alarm_notify);
        irq_set_irq_type(alarm_irq, IRQ_TYPE_EDGE_BOTH);
        return devm_request_irq(dev, alarm_irq, fan_alarm_irq_handler,
                                IRQF_SHARED, "GPIO fan alarm", fan_data);
}

/*
 * Control GPIOs.
 */

/* Must be called with fan_data->lock held, except during initialization. */
static void __set_fan_ctrl(struct gpio_fan_data *fan_data, int ctrl_val)
{
        int i;

        for (i = 0; i < fan_data->num_gpios; i++)
                gpiod_set_value_cansleep(fan_data->gpios[i],
                                         (ctrl_val >> i) & 1);
}

static int __get_fan_ctrl(struct gpio_fan_data *fan_data)
{
        int i;
        int ctrl_val = 0;

        for (i = 0; i < fan_data->num_gpios; i++) {
                int value;

                value = gpiod_get_value_cansleep(fan_data->gpios[i]);
                ctrl_val |= (value << i);
        }
        return ctrl_val;
}

/* Must be called with fan_data->lock held, except during initialization. */
static void set_fan_speed(struct gpio_fan_data *fan_data, int speed_index)
{
        if (fan_data->speed_index == speed_index)
                return;

        __set_fan_ctrl(fan_data, fan_data->speed[speed_index].ctrl_val);
        fan_data->speed_index = speed_index;
}

static int get_fan_speed_index(struct gpio_fan_data *fan_data)
{
        int ctrl_val = __get_fan_ctrl(fan_data);
        int i;

        for (i = 0; i < fan_data->num_speed; i++)
                if (fan_data->speed[i].ctrl_val == ctrl_val)
                        return i;

        dev_warn(fan_data->dev,
                 "missing speed array entry for GPIO value 0x%x\n", ctrl_val);

        return -ENODEV;
}

static int rpm_to_speed_index(struct gpio_fan_data *fan_data, unsigned long rpm)
{
        struct gpio_fan_speed *speed = fan_data->speed;
        int i;

        for (i = 0; i < fan_data->num_speed; i++)
                if (speed[i].rpm >= rpm)
                        return i;

        return fan_data->num_speed - 1;
}

static ssize_t pwm1_show(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
        u8 pwm = fan_data->speed_index * 255 / (fan_data->num_speed - 1);

        return sprintf(buf, "%d\n", pwm);
}

static ssize_t pwm1_store(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t count)
{
        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
        unsigned long pwm;
        int speed_index;
        int ret = count;

        if (kstrtoul(buf, 10, &pwm) || pwm > 255)
                return -EINVAL;

        mutex_lock(&fan_data->lock);

        if (!fan_data->pwm_enable) {
                ret = -EPERM;
                goto exit_unlock;
        }

        speed_index = DIV_ROUND_UP(pwm * (fan_data->num_speed - 1), 255);
        set_fan_speed(fan_data, speed_index);

exit_unlock:
        mutex_unlock(&fan_data->lock);

        return ret;
}

static ssize_t pwm1_enable_show(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

        return sprintf(buf, "%d\n", fan_data->pwm_enable);
}

static ssize_t pwm1_enable_store(struct device *dev,
                                 struct device_attribute *attr,
                                 const char *buf, size_t count)
{
        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
        unsigned long val;

        if (kstrtoul(buf, 10, &val) || val > 1)
                return -EINVAL;

        if (fan_data->pwm_enable == val)
                return count;

        mutex_lock(&fan_data->lock);

        fan_data->pwm_enable = val;

        /* Disable manual control mode: set fan at full speed. */
        if (val == 0)
                set_fan_speed(fan_data, fan_data->num_speed - 1);

        mutex_unlock(&fan_data->lock);

        return count;
}

static ssize_t pwm1_mode_show(struct device *dev,
                              struct device_attribute *attr, char *buf)
{
        return sprintf(buf, "0\n");
}

static ssize_t fan1_min_show(struct device *dev,
                             struct device_attribute *attr, char *buf)
{
        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

        return sprintf(buf, "%d\n", fan_data->speed[0].rpm);
}

static ssize_t fan1_max_show(struct device *dev,
                             struct device_attribute *attr, char *buf)
{
        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

        return sprintf(buf, "%d\n",
                       fan_data->speed[fan_data->num_speed - 1].rpm);
}

static ssize_t fan1_input_show(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

        return sprintf(buf, "%d\n", fan_data->speed[fan_data->speed_index].rpm);
}

static ssize_t set_rpm(struct device *dev, struct device_attribute *attr,
                       const char *buf, size_t count)
{
        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
        unsigned long rpm;
        int ret = count;

        if (kstrtoul(buf, 10, &rpm))
                return -EINVAL;

        mutex_lock(&fan_data->lock);

        if (!fan_data->pwm_enable) {
                ret = -EPERM;
                goto exit_unlock;
        }

        set_fan_speed(fan_data, rpm_to_speed_index(fan_data, rpm));

exit_unlock:
        mutex_unlock(&fan_data->lock);

        return ret;
}

static DEVICE_ATTR_RW(pwm1);
static DEVICE_ATTR_RW(pwm1_enable);
static DEVICE_ATTR_RO(pwm1_mode);
static DEVICE_ATTR_RO(fan1_min);
static DEVICE_ATTR_RO(fan1_max);
static DEVICE_ATTR_RO(fan1_input);
static DEVICE_ATTR(fan1_target, 0644, fan1_input_show, set_rpm);

static umode_t gpio_fan_is_visible(struct kobject *kobj,
                                   struct attribute *attr, int index)
{
        struct device *dev = container_of(kobj, struct device, kobj);
        struct gpio_fan_data *data = dev_get_drvdata(dev);

        if (index == 0 && !data->alarm_gpio)
                return 0;
        if (index > 0 && !data->gpios)
                return 0;

        return attr->mode;
}

static struct attribute *gpio_fan_attributes[] = {
        &dev_attr_fan1_alarm.attr,              /* 0 */
        &dev_attr_pwm1.attr,                    /* 1 */
        &dev_attr_pwm1_enable.attr,
        &dev_attr_pwm1_mode.attr,
        &dev_attr_fan1_input.attr,
        &dev_attr_fan1_target.attr,
        &dev_attr_fan1_min.attr,
        &dev_attr_fan1_max.attr,
        NULL
};

static const struct attribute_group gpio_fan_group = {
        .attrs = gpio_fan_attributes,
        .is_visible = gpio_fan_is_visible,
};

static const struct attribute_group *gpio_fan_groups[] = {
        &gpio_fan_group,
        NULL
};

static int fan_ctrl_init(struct gpio_fan_data *fan_data)
{
        int num_gpios = fan_data->num_gpios;
        struct gpio_desc **gpios = fan_data->gpios;
        int i, err;

        for (i = 0; i < num_gpios; i++) {
                /*
                 * The GPIO descriptors were retrieved with GPIOD_ASIS so here
                 * we set the GPIO into output mode, carefully preserving the
                 * current value by setting it to whatever it is already set
                 * (no surprise changes in default fan speed).
                 */
                err = gpiod_direction_output(gpios[i],
                                        gpiod_get_value_cansleep(gpios[i]));
                if (err)
                        return err;
        }

        fan_data->pwm_enable = true; /* Enable manual fan speed control. */
        fan_data->speed_index = get_fan_speed_index(fan_data);
        if (fan_data->speed_index < 0)
                return fan_data->speed_index;

        return 0;
}

static int gpio_fan_get_max_state(struct thermal_cooling_device *cdev,
                                  unsigned long *state)
{
        struct gpio_fan_data *fan_data = cdev->devdata;

        if (!fan_data)
                return -EINVAL;

        *state = fan_data->num_speed - 1;
        return 0;
}

static int gpio_fan_get_cur_state(struct thermal_cooling_device *cdev,
                                  unsigned long *state)
{
        struct gpio_fan_data *fan_data = cdev->devdata;

        if (!fan_data)
                return -EINVAL;

        *state = fan_data->speed_index;
        return 0;
}

static int gpio_fan_set_cur_state(struct thermal_cooling_device *cdev,
                                  unsigned long state)
{
        struct gpio_fan_data *fan_data = cdev->devdata;

        if (!fan_data)
                return -EINVAL;

        set_fan_speed(fan_data, state);
        return 0;
}

static const struct thermal_cooling_device_ops gpio_fan_cool_ops = {
        .get_max_state = gpio_fan_get_max_state,
        .get_cur_state = gpio_fan_get_cur_state,
        .set_cur_state = gpio_fan_set_cur_state,
};

/*
 * Translate OpenFirmware node properties into platform_data
 */
static int gpio_fan_get_of_data(struct gpio_fan_data *fan_data)
{
        struct gpio_fan_speed *speed;
        struct device *dev = fan_data->dev;
        struct device_node *np = dev->of_node;
        struct gpio_desc **gpios;
        unsigned i;
        u32 u;
        struct property *prop;
        const __be32 *p;

        /* Alarm GPIO if one exists */
        fan_data->alarm_gpio = devm_gpiod_get_optional(dev, "alarm", GPIOD_IN);
        if (IS_ERR(fan_data->alarm_gpio))
                return PTR_ERR(fan_data->alarm_gpio);

        /* Fill GPIO pin array */
        fan_data->num_gpios = gpiod_count(dev, NULL);
        if (fan_data->num_gpios <= 0) {
                if (fan_data->alarm_gpio)
                        return 0;
                dev_err(dev, "DT properties empty / missing");
                return -ENODEV;
        }
        gpios = devm_kcalloc(dev,
                             fan_data->num_gpios, sizeof(struct gpio_desc *),
                             GFP_KERNEL);
        if (!gpios)
                return -ENOMEM;
        for (i = 0; i < fan_data->num_gpios; i++) {
                gpios[i] = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS);
                if (IS_ERR(gpios[i]))
                        return PTR_ERR(gpios[i]);
        }
        fan_data->gpios = gpios;

        /* Get number of RPM/ctrl_val pairs in speed map */
        prop = of_find_property(np, "gpio-fan,speed-map", &i);
        if (!prop) {
                dev_err(dev, "gpio-fan,speed-map DT property missing");
                return -ENODEV;
        }
        i = i / sizeof(u32);
        if (i == 0 || i & 1) {
                dev_err(dev, "gpio-fan,speed-map contains zero/odd number of entries");
                return -ENODEV;
        }
        fan_data->num_speed = i / 2;

        /*
         * Populate speed map
         * Speed map is in the form <RPM ctrl_val RPM ctrl_val ...>
         * this needs splitting into pairs to create gpio_fan_speed structs
         */
        speed = devm_kcalloc(dev,
                        fan_data->num_speed, sizeof(struct gpio_fan_speed),
                        GFP_KERNEL);
        if (!speed)
                return -ENOMEM;
        p = NULL;
        for (i = 0; i < fan_data->num_speed; i++) {
                p = of_prop_next_u32(prop, p, &u);
                if (!p)
                        return -ENODEV;
                speed[i].rpm = u;
                p = of_prop_next_u32(prop, p, &u);
                if (!p)
                        return -ENODEV;
                speed[i].ctrl_val = u;
        }
        fan_data->speed = speed;

        return 0;
}

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

static void gpio_fan_stop(void *data)
{
        set_fan_speed(data, 0);
}

static int gpio_fan_probe(struct platform_device *pdev)
{
        int err;
        struct gpio_fan_data *fan_data;
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;

        fan_data = devm_kzalloc(dev, sizeof(struct gpio_fan_data),
                                GFP_KERNEL);
        if (!fan_data)
                return -ENOMEM;

        fan_data->dev = dev;
        err = gpio_fan_get_of_data(fan_data);
        if (err)
                return err;

        platform_set_drvdata(pdev, fan_data);
        mutex_init(&fan_data->lock);

        /* Configure control GPIOs if available. */
        if (fan_data->gpios && fan_data->num_gpios > 0) {
                if (!fan_data->speed || fan_data->num_speed <= 1)
                        return -EINVAL;
                err = fan_ctrl_init(fan_data);
                if (err)
                        return err;
                err = devm_add_action_or_reset(dev, gpio_fan_stop, fan_data);
                if (err)
                        return err;
        }

        /* Make this driver part of hwmon class. */
        fan_data->hwmon_dev =
                devm_hwmon_device_register_with_groups(dev,
                                                       "gpio_fan", fan_data,
                                                       gpio_fan_groups);
        if (IS_ERR(fan_data->hwmon_dev))
                return PTR_ERR(fan_data->hwmon_dev);

        /* Configure alarm GPIO if available. */
        if (fan_data->alarm_gpio) {
                err = fan_alarm_init(fan_data);
                if (err)
                        return err;
        }

        /* Optional cooling device register for Device tree platforms */
        fan_data->cdev = devm_thermal_of_cooling_device_register(dev, np,
                                "gpio-fan", fan_data, &gpio_fan_cool_ops);

        dev_info(dev, "GPIO fan initialized\n");

        return 0;
}

static void gpio_fan_shutdown(struct platform_device *pdev)
{
        struct gpio_fan_data *fan_data = platform_get_drvdata(pdev);

        if (fan_data->gpios)
                set_fan_speed(fan_data, 0);
}

#ifdef CONFIG_PM_SLEEP
static int gpio_fan_suspend(struct device *dev)
{
        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

        if (fan_data->gpios) {
                fan_data->resume_speed = fan_data->speed_index;
                set_fan_speed(fan_data, 0);
        }

        return 0;
}

static int gpio_fan_resume(struct device *dev)
{
        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

        if (fan_data->gpios)
                set_fan_speed(fan_data, fan_data->resume_speed);

        return 0;
}

static SIMPLE_DEV_PM_OPS(gpio_fan_pm, gpio_fan_suspend, gpio_fan_resume);
#define GPIO_FAN_PM     (&gpio_fan_pm)
#else
#define GPIO_FAN_PM     NULL
#endif

static struct platform_driver gpio_fan_driver = {
        .probe          = gpio_fan_probe,
        .shutdown       = gpio_fan_shutdown,
        .driver = {
                .name   = "gpio-fan",
                .pm     = GPIO_FAN_PM,
                .of_match_table = of_match_ptr(of_gpio_fan_match),
        },
};

module_platform_driver(gpio_fan_driver);

MODULE_AUTHOR("Simon Guinot <sguinot@lacie.com>");
MODULE_DESCRIPTION("GPIO FAN driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:gpio-fan");