/*
   * fixed.c
   *
   * Copyright 2008 Wolfson Microelectronics PLC.
   *
   * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
   *
   * Copyright (c) 2009 Nokia Corporation
   * Roger Quadros <ext-roger.quadros@nokia.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 is useful for systems with mixed controllable and
   * non-controllable regulators, as well as for allowing testing on
   * systems with no controllable regulators.
   */
  
  #include <linux/clk.h>
  #include <linux/err.h>
  #include <linux/mutex.h>
  #include <linux/module.h>
  #include <linux/platform_device.h>
  #include <linux/regulator/driver.h>
  #include <linux/regulator/fixed.h>
  #include <linux/gpio.h>
  #include <linux/slab.h>
  #include <linux/of.h>
  #include <linux/of_gpio.h>
  #include <linux/regulator/of_regulator.h>
  #include <linux/regulator/machine.h>
  
  struct fixed_voltage_data {
  	struct regulator_desc desc;
  	struct regulator_dev *dev;
  };
  
  
  /**
   * of_get_fixed_voltage_config - extract fixed_voltage_config structure info
   * @dev: device requesting for fixed_voltage_config
   *
   * Populates fixed_voltage_config structure by extracting data from device
   * tree node, returns a pointer to the populated structure of NULL if memory
   * alloc fails.
   */
  static struct fixed_voltage_config *
  of_get_fixed_voltage_config(struct device *dev)
  {
  	struct fixed_voltage_config *config;
  	struct device_node *np = dev->of_node;
  	const __be32 *delay;
  	struct regulator_init_data *init_data;
  
  	config = devm_kzalloc(dev, sizeof(struct fixed_voltage_config),
  								 GFP_KERNEL);
  	if (!config)
  		return ERR_PTR(-ENOMEM);
  
  	config->init_data = of_get_regulator_init_data(dev, dev->of_node);
  	if (!config->init_data)
  		return ERR_PTR(-EINVAL);
  
  	init_data = config->init_data;
  	init_data->constraints.apply_uV = 0;
  
  	config->supply_name = init_data->constraints.name;
  	if (init_data->constraints.min_uV == init_data->constraints.max_uV) {
  		config->microvolts = init_data->constraints.min_uV;
  	} else {
  		dev_err(dev,
  			 "Fixed regulator specified with variable voltages
  ");
  		return ERR_PTR(-EINVAL);
  	}
  
  	if (init_data->constraints.boot_on)
  		config->enabled_at_boot = true;
  
  	config->gpio = of_get_named_gpio(np, "gpio", 0);
  	/*
  	 * of_get_named_gpio() currently returns ENODEV rather than
  	 * EPROBE_DEFER. This code attempts to be compatible with both
  	 * for now; the ENODEV check can be removed once the API is fixed.
  	 * of_get_named_gpio() doesn't differentiate between a missing
  	 * property (which would be fine here, since the GPIO is optional)
  	 * and some other error. Patches have been posted for both issues.
  	 * Once they are check in, we should replace this with:
  	 * if (config->gpio < 0 && config->gpio != -ENOENT)
  	 */
  	if ((config->gpio == -ENODEV) || (config->gpio == -EPROBE_DEFER))
  		return ERR_PTR(-EPROBE_DEFER);
  
  	delay = of_get_property(np, "startup-delay-us", NULL);
  	if (delay)
  		config->startup_delay = be32_to_cpu(*delay);
  
  	if (of_find_property(np, "enable-active-high", NULL))
  		config->enable_high = true;
  
  	if (of_find_property(np, "gpio-open-drain", NULL))
  		config->gpio_is_open_drain = true;
  
  	if (of_find_property(np, "vin-supply", NULL))
  		config->input_supply = "vin";
  
  	return config;
  }
  
  static struct regulator_ops fixed_voltage_ops = {
  };
  
  static int reg_fixed_voltage_probe(struct platform_device *pdev)
  {
  	struct fixed_voltage_config *config;
  	struct fixed_voltage_data *drvdata;
  	struct regulator_config cfg = { };
  	int ret;
  	struct clk *clk_slow;
  
  	if (pdev->dev.of_node) {
  		config = of_get_fixed_voltage_config(&pdev->dev);
  		if (IS_ERR(config))
  			return PTR_ERR(config);
  	} else {
  		config = dev_get_platdata(&pdev->dev);
  	}
  
  	if (!config)
  		return -ENOMEM;
  
  	drvdata = devm_kzalloc(&pdev->dev, sizeof(struct fixed_voltage_data),
  			       GFP_KERNEL);
  	if (drvdata == NULL) {
  		dev_err(&pdev->dev, "Failed to allocate device data
  ");
  		ret = -ENOMEM;
  		goto err;
  	}
  
  	clk_slow = devm_clk_get(&pdev->dev, "slow");
  	if (!IS_ERR(clk_slow))
  		clk_prepare_enable(clk_slow);
  
  	drvdata->desc.name = kstrdup(config->supply_name, GFP_KERNEL);
  	if (drvdata->desc.name == NULL) {
  		dev_err(&pdev->dev, "Failed to allocate supply name
  ");
  		ret = -ENOMEM;
  		goto err;
  	}
  	drvdata->desc.type = REGULATOR_VOLTAGE;
  	drvdata->desc.owner = THIS_MODULE;
  	drvdata->desc.ops = &fixed_voltage_ops;
  
  	drvdata->desc.enable_time = config->startup_delay;
  
  	if (config->input_supply) {
  		drvdata->desc.supply_name = kstrdup(config->input_supply,
  							GFP_KERNEL);
  		if (!drvdata->desc.supply_name) {
  			dev_err(&pdev->dev,
  				"Failed to allocate input supply
  ");
  			ret = -ENOMEM;
  			goto err_name;
  		}
  	}
  
  	if (config->microvolts)
  		drvdata->desc.n_voltages = 1;
  
  	drvdata->desc.fixed_uV = config->microvolts;
  
  	if (config->gpio >= 0)
  		cfg.ena_gpio = config->gpio;
  	cfg.ena_gpio_invert = !config->enable_high;
  	if (config->enabled_at_boot) {
  		if (config->enable_high)
  			cfg.ena_gpio_flags |= GPIOF_OUT_INIT_HIGH;
  		else
  			cfg.ena_gpio_flags |= GPIOF_OUT_INIT_LOW;
  	} else {
  		if (config->enable_high)
  			cfg.ena_gpio_flags |= GPIOF_OUT_INIT_LOW;
  		else
  			cfg.ena_gpio_flags |= GPIOF_OUT_INIT_HIGH;
  	}
  	if (config->gpio_is_open_drain)
  		cfg.ena_gpio_flags |= GPIOF_OPEN_DRAIN;
  
  	cfg.dev = &pdev->dev;
  	cfg.init_data = config->init_data;
  	cfg.driver_data = drvdata;
  	cfg.of_node = pdev->dev.of_node;
  
  	drvdata->dev = regulator_register(&drvdata->desc, &cfg);
  	if (IS_ERR(drvdata->dev)) {
  		ret = PTR_ERR(drvdata->dev);
  		dev_err(&pdev->dev, "Failed to register regulator: %d
  ", ret);
  		goto err_input;
  	}
  
  	platform_set_drvdata(pdev, drvdata);
  
  	dev_dbg(&pdev->dev, "%s supplying %duV
  ", drvdata->desc.name,
  		drvdata->desc.fixed_uV);
  
  	return 0;
  
  err_input:
  	kfree(drvdata->desc.supply_name);
  err_name:
  	kfree(drvdata->desc.name);
  err:
  	return ret;
  }
  
  static int reg_fixed_voltage_remove(struct platform_device *pdev)
  {
  	struct fixed_voltage_data *drvdata = platform_get_drvdata(pdev);
  
  	regulator_unregister(drvdata->dev);
  	kfree(drvdata->desc.supply_name);
  	kfree(drvdata->desc.name);
  
  	return 0;
  }
  
  #if defined(CONFIG_OF)
  static const struct of_device_id fixed_of_match[] = {
  	{ .compatible = "regulator-fixed", },
  	{},
  };
  MODULE_DEVICE_TABLE(of, fixed_of_match);
  #endif
  
  static struct platform_driver regulator_fixed_voltage_driver = {
  	.probe		= reg_fixed_voltage_probe,
  	.remove		= reg_fixed_voltage_remove,
  	.driver		= {
  		.name		= "reg-fixed-voltage",
  		.owner		= THIS_MODULE,
  		.of_match_table = of_match_ptr(fixed_of_match),
  	},
  };
  
  static int __init regulator_fixed_voltage_init(void)
  {
  	return platform_driver_register(&regulator_fixed_voltage_driver);
  }
  subsys_initcall(regulator_fixed_voltage_init);
  
  static void __exit regulator_fixed_voltage_exit(void)
  {
  	platform_driver_unregister(&regulator_fixed_voltage_driver);
  }
  module_exit(regulator_fixed_voltage_exit);
  
  MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
  MODULE_DESCRIPTION("Fixed voltage regulator");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:reg-fixed-voltage");