/*
   * 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>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   */
  
  #include <linux/hwmon.h>
  #include <linux/hwmon-sysfs.h>
  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/of.h>
  #include <linux/platform_device.h>
  #include <linux/pwm.h>
  #include <linux/sysfs.h>

  #include <linux/thermal.h>

  
  #define MAX_PWM 255
  
  struct pwm_fan_ctx {
  	struct mutex lock;
  	struct pwm_device *pwm;

  	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;

  };

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

  {

  	struct pwm_args pargs;

  	unsigned long duty;
  	int ret = 0;

  	pwm_get_args(ctx->pwm, &pargs);

  	mutex_lock(&ctx->lock);

  	if (ctx->pwm_value == pwm)

  		goto exit_set_pwm_err;

  	duty = DIV_ROUND_UP(pwm * (pargs.period - 1), MAX_PWM);
  	ret = pwm_config(ctx->pwm, duty, pargs.period);

  	if (ret)
  		goto exit_set_pwm_err;

  	if (pwm == 0)
  		pwm_disable(ctx->pwm);

  	if (ctx->pwm_value == 0) {
  		ret = pwm_enable(ctx->pwm);
  		if (ret)
  			goto exit_set_pwm_err;
  	}

  	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 set_pwm(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 show_pwm(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 SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm, 0);
  
  static struct attribute *pwm_fan_attrs[] = {
  	&sensor_dev_attr_pwm1.dev_attr.attr,
  	NULL,
  };
  
  ATTRIBUTE_GROUPS(pwm_fan);

  /* 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_kzalloc(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 int pwm_fan_probe(struct platform_device *pdev)
  {

  	struct thermal_cooling_device *cdev;

  	struct pwm_fan_ctx *ctx;

  	struct pwm_args pargs;

  	struct device *hwmon;

  	int duty_cycle;
  	int ret;
  
  	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
  	if (!ctx)
  		return -ENOMEM;
  
  	mutex_init(&ctx->lock);
  
  	ctx->pwm = devm_of_pwm_get(&pdev->dev, pdev->dev.of_node, NULL);
  	if (IS_ERR(ctx->pwm)) {
  		dev_err(&pdev->dev, "Could not get PWM
  ");
  		return PTR_ERR(ctx->pwm);
  	}

  	platform_set_drvdata(pdev, ctx);

  	/*
  	 * FIXME: pwm_apply_args() should be removed when switching to the
  	 * atomic PWM API.
  	 */
  	pwm_apply_args(ctx->pwm);

  	/* Set duty cycle to maximum allowed */

  	pwm_get_args(ctx->pwm, &pargs);
  
  	duty_cycle = pargs.period - 1;

  	ctx->pwm_value = MAX_PWM;

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

  	if (ret) {
  		dev_err(&pdev->dev, "Failed to configure PWM
  ");
  		return ret;
  	}
  
  	/* Enbale PWM output */
  	ret = pwm_enable(ctx->pwm);
  	if (ret) {
  		dev_err(&pdev->dev, "Failed to enable PWM
  ");
  		return ret;
  	}
  
  	hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
  						       ctx, pwm_fan_groups);
  	if (IS_ERR(hwmon)) {
  		dev_err(&pdev->dev, "Failed to register hwmon device
  ");
  		pwm_disable(ctx->pwm);
  		return PTR_ERR(hwmon);
  	}

  
  	ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
  	if (ret)
  		return ret;

  	ctx->pwm_fan_state = ctx->pwm_fan_max_state;
  	if (IS_ENABLED(CONFIG_THERMAL)) {
  		cdev = thermal_of_cooling_device_register(pdev->dev.of_node,
  							  "pwm-fan", ctx,
  							  &pwm_fan_cooling_ops);
  		if (IS_ERR(cdev)) {
  			dev_err(&pdev->dev,
  				"Failed to register pwm-fan as cooling device");
  			pwm_disable(ctx->pwm);
  			return PTR_ERR(cdev);
  		}
  		ctx->cdev = cdev;
  		thermal_cdev_update(cdev);
  	}

  	return 0;
  }
  
  static int pwm_fan_remove(struct platform_device *pdev)
  {
  	struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);

  	thermal_cooling_device_unregister(ctx->cdev);

  	if (ctx->pwm_value)
  		pwm_disable(ctx->pwm);
  	return 0;
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int pwm_fan_suspend(struct device *dev)
  {
  	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
  
  	if (ctx->pwm_value)
  		pwm_disable(ctx->pwm);
  	return 0;
  }
  
  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->pwm_value == 0)
  		return 0;

  	pwm_get_args(ctx->pwm, &pargs);
  	duty = DIV_ROUND_UP(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,
  	.remove		= pwm_fan_remove,
  	.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");