/*
   * reg-virtual-consumer.c
   *
   * Copyright 2008 Wolfson Microelectronics PLC.
   *
   * Author: Mark Brown <broonie@opensource.wolfsonmicro.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.
   */
  
  #include <linux/err.h>
  #include <linux/mutex.h>
  #include <linux/platform_device.h>
  #include <linux/regulator/consumer.h>

  #include <linux/slab.h>

  #include <linux/module.h>

  
  struct virtual_consumer_data {
  	struct mutex lock;
  	struct regulator *regulator;

  	bool enabled;

  	int min_uV;
  	int max_uV;
  	int min_uA;
  	int max_uA;
  	unsigned int mode;
  };

  static void update_voltage_constraints(struct device *dev,
  				       struct virtual_consumer_data *data)

  {
  	int ret;
  
  	if (data->min_uV && data->max_uV
  	    && data->min_uV <= data->max_uV) {

  		dev_dbg(dev, "Requesting %d-%duV
  ",
  			data->min_uV, data->max_uV);

  		ret = regulator_set_voltage(data->regulator,

  					data->min_uV, data->max_uV);

  		if (ret != 0) {

  			dev_err(dev,
  				"regulator_set_voltage() failed: %d
  ", ret);

  			return;
  		}
  	}
  
  	if (data->min_uV && data->max_uV && !data->enabled) {

  		dev_dbg(dev, "Enabling regulator
  ");

  		ret = regulator_enable(data->regulator);
  		if (ret == 0)

  			data->enabled = true;

  		else

  			dev_err(dev, "regulator_enable() failed: %d
  ",

  				ret);
  	}
  
  	if (!(data->min_uV && data->max_uV) && data->enabled) {

  		dev_dbg(dev, "Disabling regulator
  ");

  		ret = regulator_disable(data->regulator);
  		if (ret == 0)

  			data->enabled = false;

  		else

  			dev_err(dev, "regulator_disable() failed: %d
  ",

  				ret);
  	}
  }

  static void update_current_limit_constraints(struct device *dev,
  					  struct virtual_consumer_data *data)

  {
  	int ret;
  
  	if (data->max_uA
  	    && data->min_uA <= data->max_uA) {

  		dev_dbg(dev, "Requesting %d-%duA
  ",
  			data->min_uA, data->max_uA);

  		ret = regulator_set_current_limit(data->regulator,
  					data->min_uA, data->max_uA);
  		if (ret != 0) {

  			dev_err(dev,
  				"regulator_set_current_limit() failed: %d
  ",
  				ret);

  			return;
  		}
  	}
  
  	if (data->max_uA && !data->enabled) {

  		dev_dbg(dev, "Enabling regulator
  ");

  		ret = regulator_enable(data->regulator);
  		if (ret == 0)

  			data->enabled = true;

  		else

  			dev_err(dev, "regulator_enable() failed: %d
  ",

  				ret);
  	}
  
  	if (!(data->min_uA && data->max_uA) && data->enabled) {

  		dev_dbg(dev, "Disabling regulator
  ");

  		ret = regulator_disable(data->regulator);
  		if (ret == 0)

  			data->enabled = false;

  		else

  			dev_err(dev, "regulator_disable() failed: %d
  ",

  				ret);
  	}
  }
  
  static ssize_t show_min_uV(struct device *dev,
  			   struct device_attribute *attr, char *buf)
  {
  	struct virtual_consumer_data *data = dev_get_drvdata(dev);
  	return sprintf(buf, "%d
  ", data->min_uV);
  }
  
  static ssize_t set_min_uV(struct device *dev, struct device_attribute *attr,
  			  const char *buf, size_t count)
  {
  	struct virtual_consumer_data *data = dev_get_drvdata(dev);
  	long val;

  	if (kstrtol(buf, 10, &val) != 0)

  		return count;
  
  	mutex_lock(&data->lock);
  
  	data->min_uV = val;

  	update_voltage_constraints(dev, data);

  
  	mutex_unlock(&data->lock);
  
  	return count;
  }
  
  static ssize_t show_max_uV(struct device *dev,
  			   struct device_attribute *attr, char *buf)
  {
  	struct virtual_consumer_data *data = dev_get_drvdata(dev);
  	return sprintf(buf, "%d
  ", data->max_uV);
  }
  
  static ssize_t set_max_uV(struct device *dev, struct device_attribute *attr,
  			  const char *buf, size_t count)
  {
  	struct virtual_consumer_data *data = dev_get_drvdata(dev);
  	long val;

  	if (kstrtol(buf, 10, &val) != 0)

  		return count;
  
  	mutex_lock(&data->lock);
  
  	data->max_uV = val;

  	update_voltage_constraints(dev, data);

  
  	mutex_unlock(&data->lock);
  
  	return count;
  }
  
  static ssize_t show_min_uA(struct device *dev,
  			   struct device_attribute *attr, char *buf)
  {
  	struct virtual_consumer_data *data = dev_get_drvdata(dev);
  	return sprintf(buf, "%d
  ", data->min_uA);
  }
  
  static ssize_t set_min_uA(struct device *dev, struct device_attribute *attr,
  			  const char *buf, size_t count)
  {
  	struct virtual_consumer_data *data = dev_get_drvdata(dev);
  	long val;

  	if (kstrtol(buf, 10, &val) != 0)

  		return count;
  
  	mutex_lock(&data->lock);
  
  	data->min_uA = val;

  	update_current_limit_constraints(dev, data);

  
  	mutex_unlock(&data->lock);
  
  	return count;
  }
  
  static ssize_t show_max_uA(struct device *dev,
  			   struct device_attribute *attr, char *buf)
  {
  	struct virtual_consumer_data *data = dev_get_drvdata(dev);
  	return sprintf(buf, "%d
  ", data->max_uA);
  }
  
  static ssize_t set_max_uA(struct device *dev, struct device_attribute *attr,
  			  const char *buf, size_t count)
  {
  	struct virtual_consumer_data *data = dev_get_drvdata(dev);
  	long val;

  	if (kstrtol(buf, 10, &val) != 0)

  		return count;
  
  	mutex_lock(&data->lock);
  
  	data->max_uA = val;

  	update_current_limit_constraints(dev, data);

  
  	mutex_unlock(&data->lock);
  
  	return count;
  }
  
  static ssize_t show_mode(struct device *dev,
  			 struct device_attribute *attr, char *buf)
  {
  	struct virtual_consumer_data *data = dev_get_drvdata(dev);
  
  	switch (data->mode) {
  	case REGULATOR_MODE_FAST:
  		return sprintf(buf, "fast
  ");
  	case REGULATOR_MODE_NORMAL:
  		return sprintf(buf, "normal
  ");
  	case REGULATOR_MODE_IDLE:
  		return sprintf(buf, "idle
  ");
  	case REGULATOR_MODE_STANDBY:
  		return sprintf(buf, "standby
  ");
  	default:
  		return sprintf(buf, "unknown
  ");
  	}
  }
  
  static ssize_t set_mode(struct device *dev, struct device_attribute *attr,
  			const char *buf, size_t count)
  {
  	struct virtual_consumer_data *data = dev_get_drvdata(dev);
  	unsigned int mode;
  	int ret;

  	/*
  	 * sysfs_streq() doesn't need the 
  's, but we add them so the strings
  	 * will be shared with show_mode(), above.
  	 */

  	if (sysfs_streq(buf, "fast
  "))

  		mode = REGULATOR_MODE_FAST;

  	else if (sysfs_streq(buf, "normal
  "))

  		mode = REGULATOR_MODE_NORMAL;

  	else if (sysfs_streq(buf, "idle
  "))

  		mode = REGULATOR_MODE_IDLE;

  	else if (sysfs_streq(buf, "standby
  "))

  		mode = REGULATOR_MODE_STANDBY;
  	else {
  		dev_err(dev, "Configuring invalid mode
  ");
  		return count;
  	}
  
  	mutex_lock(&data->lock);
  	ret = regulator_set_mode(data->regulator, mode);
  	if (ret == 0)
  		data->mode = mode;
  	else
  		dev_err(dev, "Failed to configure mode: %d
  ", ret);
  	mutex_unlock(&data->lock);
  
  	return count;
  }

  static DEVICE_ATTR(min_microvolts, 0664, show_min_uV, set_min_uV);
  static DEVICE_ATTR(max_microvolts, 0664, show_max_uV, set_max_uV);
  static DEVICE_ATTR(min_microamps, 0664, show_min_uA, set_min_uA);
  static DEVICE_ATTR(max_microamps, 0664, show_max_uA, set_max_uA);
  static DEVICE_ATTR(mode, 0664, show_mode, set_mode);

  static struct attribute *regulator_virtual_attributes[] = {
  	&dev_attr_min_microvolts.attr,
  	&dev_attr_max_microvolts.attr,
  	&dev_attr_min_microamps.attr,
  	&dev_attr_max_microamps.attr,
  	&dev_attr_mode.attr,
  	NULL

  };

  static const struct attribute_group regulator_virtual_attr_group = {
  	.attrs	= regulator_virtual_attributes,
  };

  static int regulator_virtual_probe(struct platform_device *pdev)

  {

  	char *reg_id = dev_get_platdata(&pdev->dev);

  	struct virtual_consumer_data *drvdata;

  	int ret;

  	drvdata = devm_kzalloc(&pdev->dev, sizeof(struct virtual_consumer_data),
  			       GFP_KERNEL);

  	if (drvdata == NULL)

  		return -ENOMEM;

  
  	mutex_init(&drvdata->lock);

  	drvdata->regulator = devm_regulator_get(&pdev->dev, reg_id);

  	if (IS_ERR(drvdata->regulator)) {
  		ret = PTR_ERR(drvdata->regulator);

  		dev_err(&pdev->dev, "Failed to obtain supply '%s': %d
  ",
  			reg_id, ret);

  		return ret;

  	}

  	ret = sysfs_create_group(&pdev->dev.kobj,
  				 &regulator_virtual_attr_group);
  	if (ret != 0) {
  		dev_err(&pdev->dev,
  			"Failed to create attribute group: %d
  ", ret);

  		return ret;

  	}
  
  	drvdata->mode = regulator_get_mode(drvdata->regulator);
  
  	platform_set_drvdata(pdev, drvdata);
  
  	return 0;

  }

  static int regulator_virtual_remove(struct platform_device *pdev)

  {
  	struct virtual_consumer_data *drvdata = platform_get_drvdata(pdev);

  	sysfs_remove_group(&pdev->dev.kobj, &regulator_virtual_attr_group);

  	if (drvdata->enabled)
  		regulator_disable(drvdata->regulator);

  
  	return 0;
  }
  
  static struct platform_driver regulator_virtual_consumer_driver = {

  	.probe		= regulator_virtual_probe,

  	.remove		= regulator_virtual_remove,

  	.driver		= {
  		.name		= "reg-virt-consumer",
  	},
  };

  module_platform_driver(regulator_virtual_consumer_driver);

  
  MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
  MODULE_DESCRIPTION("Virtual regulator consumer");
  MODULE_LICENSE("GPL");

  MODULE_ALIAS("platform:reg-virt-consumer");