// 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/hwmon.h>
  #include <linux/hwmon-sysfs.h>

  #include <linux/interrupt.h>

  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/of.h>
  #include <linux/platform_device.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_ctx {
  	struct mutex lock;
  	struct pwm_device *pwm;

  	struct regulator *reg_en;

  
  	int irq;
  	atomic_t pulses;
  	unsigned int rpm;
  	u8 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;

  };

  /* This handler assumes self resetting edge triggered interrupt. */
  static irqreturn_t pulse_handler(int irq, void *dev_id)
  {
  	struct pwm_fan_ctx *ctx = dev_id;
  
  	atomic_inc(&ctx->pulses);
  
  	return IRQ_HANDLED;
  }
  
  static void sample_timer(struct timer_list *t)
  {
  	struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);

  	unsigned int delta = ktime_ms_delta(ktime_get(), ctx->sample_start);

  	int pulses;

  	if (delta) {
  		pulses = atomic_read(&ctx->pulses);
  		atomic_sub(pulses, &ctx->pulses);
  		ctx->rpm = (unsigned int)(pulses * 1000 * 60) /
  			(ctx->pulses_per_revolution * delta);
  
  		ctx->sample_start = ktime_get();
  	}

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

  static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)

  {

  	unsigned long period;

  	int ret = 0;

  	struct pwm_state state = { };

  	mutex_lock(&ctx->lock);

  	if (ctx->pwm_value == pwm)

  		goto exit_set_pwm_err;

  	pwm_init_state(ctx->pwm, &state);
  	period = ctx->pwm->args.period;
  	state.duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
  	state.enabled = pwm ? true : false;

  	ret = pwm_apply_state(ctx->pwm, &state);
  	if (!ret)
  		ctx->pwm_value = pwm;

  exit_set_pwm_err:
  	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 ssize_t pwm_store(struct device *dev, struct device_attribute *attr,
  			 const char *buf, size_t count)

  {
  	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
  	unsigned long pwm;
  	int ret;
  
  	if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
  		return -EINVAL;
  
  	ret = __set_pwm(ctx, pwm);
  	if (ret)
  		return ret;

  	pwm_fan_update_state(ctx, pwm);

  	return count;
  }

  static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
  			char *buf)

  {
  	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
  
  	return sprintf(buf, "%u
  ", ctx->pwm_value);
  }

  static ssize_t rpm_show(struct device *dev,
  			struct device_attribute *attr, char *buf)
  {
  	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
  
  	return sprintf(buf, "%u
  ", ctx->rpm);
  }

  static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);

  static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);

  
  static struct attribute *pwm_fan_attrs[] = {
  	&sensor_dev_attr_pwm1.dev_attr.attr,

  	&sensor_dev_attr_fan1_input.dev_attr.attr,

  	NULL,
  };

  static umode_t pwm_fan_attrs_visible(struct kobject *kobj, struct attribute *a,
  				     int n)
  {
  	struct device *dev = container_of(kobj, struct device, kobj);
  	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
  
  	/* Hide fan_input in case no interrupt is available  */
  	if (n == 1 && ctx->irq <= 0)
  		return 0;
  
  	return a->mode;
  }
  
  static const struct attribute_group pwm_fan_group = {
  	.attrs = pwm_fan_attrs,
  	.is_visible = pwm_fan_attrs_visible,
  };
  
  static const struct attribute_group *pwm_fan_groups[] = {
  	&pwm_fan_group,
  	NULL,
  };

  /* 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!
  ");
  		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_of_get_cooling_data(struct device *dev,
  				       struct pwm_fan_ctx *ctx)

  {
  	struct device_node *np = dev->of_node;
  	int num, i, ret;
  
  	if (!of_find_property(np, "cooling-levels", NULL))
  		return 0;
  
  	ret = of_property_count_u32_elems(np, "cooling-levels");
  	if (ret <= 0) {
  		dev_err(dev, "Wrong data!
  ");
  		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 = of_property_read_u32_array(np, "cooling-levels",
  					 ctx->pwm_fan_cooling_levels, num);
  	if (ret) {
  		dev_err(dev, "Property 'cooling-levels' cannot be read!
  ");
  		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
  ", i,
  				ctx->pwm_fan_cooling_levels[i], MAX_PWM);
  			return -EINVAL;
  		}
  	}
  
  	ctx->pwm_fan_max_state = num - 1;
  
  	return 0;
  }

  static void pwm_fan_regulator_disable(void *data)
  {
  	regulator_disable(data);
  }

  static void pwm_fan_pwm_disable(void *__ctx)

  {

  	struct pwm_fan_ctx *ctx = __ctx;
  	pwm_disable(ctx->pwm);
  	del_timer_sync(&ctx->rpm_timer);

  }

  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;

  	struct pwm_state state = { };

  	u32 ppr = 2;

  	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);

  	if (!ctx)
  		return -ENOMEM;
  
  	mutex_init(&ctx->lock);

  	ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL);

  	if (IS_ERR(ctx->pwm))
  		return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM
  ");

  	platform_set_drvdata(pdev, ctx);

  	ctx->irq = platform_get_irq_optional(pdev, 0);

  	if (ctx->irq == -EPROBE_DEFER)
  		return ctx->irq;

  	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;
  	} else {
  		ret = regulator_enable(ctx->reg_en);
  		if (ret) {

  			dev_err(dev, "Failed to enable fan supply: %d
  ", ret);

  			return ret;
  		}

  		ret = devm_add_action_or_reset(dev, pwm_fan_regulator_disable,
  					       ctx->reg_en);
  		if (ret)
  			return ret;

  	}

  	ctx->pwm_value = MAX_PWM;

  	pwm_init_state(ctx->pwm, &state);

  	/*
  	 * __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 (state.period > ULONG_MAX / MAX_PWM + 1) {
  		dev_err(dev, "Configured period too big
  ");
  		return -EINVAL;
  	}
  
  	/* Set duty cycle to maximum allowed and enable PWM output */

  	state.duty_cycle = ctx->pwm->args.period - 1;
  	state.enabled = true;

  	ret = pwm_apply_state(ctx->pwm, &state);

  	if (ret) {

  		dev_err(dev, "Failed to configure PWM: %d
  ", ret);

  		return ret;

  	}

  	timer_setup(&ctx->rpm_timer, sample_timer, 0);

  	ret = devm_add_action_or_reset(dev, pwm_fan_pwm_disable, ctx);
  	if (ret)
  		return ret;

  	of_property_read_u32(dev->of_node, "pulses-per-revolution", &ppr);

  	ctx->pulses_per_revolution = ppr;
  	if (!ctx->pulses_per_revolution) {

  		dev_err(dev, "pulses-per-revolution can't be zero.
  ");
  		return -EINVAL;

  	}
  
  	if (ctx->irq > 0) {

  		ret = devm_request_irq(dev, ctx->irq, pulse_handler, 0,

  				       pdev->name, ctx);
  		if (ret) {

  			dev_err(dev, "Failed to request interrupt: %d
  ", ret);
  			return ret;

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

  	hwmon = devm_hwmon_device_register_with_groups(dev, "pwmfan",

  						       ctx, pwm_fan_groups);
  	if (IS_ERR(hwmon)) {

  		dev_err(dev, "Failed to register hwmon device
  ");
  		return PTR_ERR(hwmon);

  	}

  	ret = pwm_fan_of_get_cooling_data(dev, ctx);

  	if (ret)
  		return ret;

  	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
  ",
  				ret);

  			return ret;

  		}
  		ctx->cdev = cdev;
  		thermal_cdev_update(cdev);
  	}

  	return 0;

  }

  static int pwm_fan_disable(struct device *dev)

  {
  	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);

  	struct pwm_args args;
  	int ret;
  
  	pwm_get_args(ctx->pwm, &args);
  
  	if (ctx->pwm_value) {
  		ret = pwm_config(ctx->pwm, 0, args.period);
  		if (ret < 0)
  			return ret;

  		pwm_disable(ctx->pwm);

  	}

  	if (ctx->reg_en) {
  		ret = regulator_disable(ctx->reg_en);
  		if (ret) {
  			dev_err(dev, "Failed to disable fan supply: %d
  ", ret);
  			return ret;
  		}
  	}

  	return 0;
  }

  static void pwm_fan_shutdown(struct platform_device *pdev)
  {
  	pwm_fan_disable(&pdev->dev);
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int pwm_fan_suspend(struct device *dev)
  {
  	return pwm_fan_disable(dev);
  }

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

  	struct pwm_args pargs;

  	unsigned long duty;
  	int ret;

  	if (ctx->reg_en) {
  		ret = regulator_enable(ctx->reg_en);
  		if (ret) {
  			dev_err(dev, "Failed to enable fan supply: %d
  ", ret);
  			return ret;
  		}
  	}

  	if (ctx->pwm_value == 0)
  		return 0;

  	pwm_get_args(ctx->pwm, &pargs);

  	duty = DIV_ROUND_UP_ULL(ctx->pwm_value * (pargs.period - 1), MAX_PWM);

  	ret = pwm_config(ctx->pwm, duty, pargs.period);

  	if (ret)
  		return ret;
  	return pwm_enable(ctx->pwm);

  }
  #endif
  
  static 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		= &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");