/*
   * System Control Driver
   *
   * Copyright (C) 2012 Freescale Semiconductor, Inc.
   * Copyright (C) 2012 Linaro Ltd.
   *
   * Author: Dong Aisheng <dong.aisheng@linaro.org>
   *
   * 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/io.h>
  #include <linux/module.h>

  #include <linux/list.h>

  #include <linux/of.h>
  #include <linux/of_address.h>
  #include <linux/of_platform.h>

  #include <linux/platform_data/syscon.h>

  #include <linux/platform_device.h>
  #include <linux/regmap.h>

  #include <linux/mfd/syscon.h>

  #include <linux/slab.h>

  
  static struct platform_driver syscon_driver;

  static DEFINE_SPINLOCK(syscon_list_slock);
  static LIST_HEAD(syscon_list);

  struct syscon {

  	struct device_node *np;

  	struct regmap *regmap;

  	struct list_head list;
  };

  static const struct regmap_config syscon_regmap_config = {

  	.reg_bits = 32,
  	.val_bits = 32,
  	.reg_stride = 4,

  };

  static struct syscon *of_syscon_register(struct device_node *np)

  {

  	struct syscon *syscon;
  	struct regmap *regmap;
  	void __iomem *base;

  	u32 reg_io_width;

  	int ret;
  	struct regmap_config syscon_config = syscon_regmap_config;

  	struct resource res;

  
  	if (!of_device_is_compatible(np, "syscon"))
  		return ERR_PTR(-EINVAL);
  
  	syscon = kzalloc(sizeof(*syscon), GFP_KERNEL);
  	if (!syscon)
  		return ERR_PTR(-ENOMEM);

  	if (of_address_to_resource(np, 0, &res)) {
  		ret = -ENOMEM;
  		goto err_map;
  	}
  
  	base = ioremap(res.start, resource_size(&res));

  	if (!base) {
  		ret = -ENOMEM;
  		goto err_map;
  	}
  
  	/* Parse the device's DT node for an endianness specification */
  	if (of_property_read_bool(np, "big-endian"))
  		syscon_config.val_format_endian = REGMAP_ENDIAN_BIG;

  	else if (of_property_read_bool(np, "little-endian"))

  		syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE;

  	else if (of_property_read_bool(np, "native-endian"))
  		syscon_config.val_format_endian = REGMAP_ENDIAN_NATIVE;

  	/*
  	 * search for reg-io-width property in DT. If it is not provided,
  	 * default to 4 bytes. regmap_init_mmio will return an error if values
  	 * are invalid so there is no need to check them here.
  	 */
  	ret = of_property_read_u32(np, "reg-io-width", &reg_io_width);
  	if (ret)
  		reg_io_width = 4;
  
  	syscon_config.reg_stride = reg_io_width;
  	syscon_config.val_bits = reg_io_width * 8;

  	syscon_config.max_register = resource_size(&res) - reg_io_width;

  	regmap = regmap_init_mmio(NULL, base, &syscon_config);
  	if (IS_ERR(regmap)) {
  		pr_err("regmap init failed
  ");
  		ret = PTR_ERR(regmap);
  		goto err_regmap;
  	}
  
  	syscon->regmap = regmap;
  	syscon->np = np;
  
  	spin_lock(&syscon_list_slock);
  	list_add_tail(&syscon->list, &syscon_list);
  	spin_unlock(&syscon_list_slock);

  	return syscon;
  
  err_regmap:
  	iounmap(base);
  err_map:
  	kfree(syscon);
  	return ERR_PTR(ret);

  }
  
  struct regmap *syscon_node_to_regmap(struct device_node *np)
  {

  	struct syscon *entry, *syscon = NULL;

  	spin_lock(&syscon_list_slock);

  	list_for_each_entry(entry, &syscon_list, list)
  		if (entry->np == np) {
  			syscon = entry;
  			break;
  		}
  
  	spin_unlock(&syscon_list_slock);
  
  	if (!syscon)
  		syscon = of_syscon_register(np);
  
  	if (IS_ERR(syscon))
  		return ERR_CAST(syscon);

  
  	return syscon->regmap;
  }
  EXPORT_SYMBOL_GPL(syscon_node_to_regmap);
  
  struct regmap *syscon_regmap_lookup_by_compatible(const char *s)
  {
  	struct device_node *syscon_np;
  	struct regmap *regmap;
  
  	syscon_np = of_find_compatible_node(NULL, NULL, s);
  	if (!syscon_np)
  		return ERR_PTR(-ENODEV);
  
  	regmap = syscon_node_to_regmap(syscon_np);
  	of_node_put(syscon_np);
  
  	return regmap;
  }
  EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_compatible);

  static int syscon_match_pdevname(struct device *dev, void *data)
  {

  	return !strcmp(dev_name(dev), (const char *)data);
  }
  
  struct regmap *syscon_regmap_lookup_by_pdevname(const char *s)
  {
  	struct device *dev;
  	struct syscon *syscon;
  
  	dev = driver_find_device(&syscon_driver.driver, NULL, (void *)s,
  				 syscon_match_pdevname);
  	if (!dev)
  		return ERR_PTR(-EPROBE_DEFER);
  
  	syscon = dev_get_drvdata(dev);
  
  	return syscon->regmap;
  }
  EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_pdevname);

  struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
  					const char *property)
  {
  	struct device_node *syscon_np;
  	struct regmap *regmap;

  	if (property)
  		syscon_np = of_parse_phandle(np, property, 0);
  	else
  		syscon_np = np;

  	if (!syscon_np)
  		return ERR_PTR(-ENODEV);
  
  	regmap = syscon_node_to_regmap(syscon_np);
  	of_node_put(syscon_np);
  
  	return regmap;
  }
  EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle);

  static int syscon_probe(struct platform_device *pdev)

  {
  	struct device *dev = &pdev->dev;

  	struct syscon_platform_data *pdata = dev_get_platdata(dev);

  	struct syscon *syscon;

  	struct regmap_config syscon_config = syscon_regmap_config;

  	struct resource *res;

  	void __iomem *base;

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

  	if (!syscon)
  		return -ENOMEM;

  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!res)
  		return -ENOENT;

  	base = devm_ioremap(dev, res->start, resource_size(res));
  	if (!base)

  		return -ENOMEM;

  	syscon_config.max_register = res->end - res->start - 3;

  	if (pdata)

  		syscon_config.name = pdata->label;
  	syscon->regmap = devm_regmap_init_mmio(dev, base, &syscon_config);

  	if (IS_ERR(syscon->regmap)) {
  		dev_err(dev, "regmap init failed
  ");
  		return PTR_ERR(syscon->regmap);
  	}

  	platform_set_drvdata(pdev, syscon);

  	dev_dbg(dev, "regmap %pR registered
  ", res);

  
  	return 0;
  }

  static const struct platform_device_id syscon_ids[] = {
  	{ "syscon", },
  	{ }
  };

  
  static struct platform_driver syscon_driver = {
  	.driver = {
  		.name = "syscon",

  	},
  	.probe		= syscon_probe,

  	.id_table	= syscon_ids,

  };
  
  static int __init syscon_init(void)
  {
  	return platform_driver_register(&syscon_driver);
  }
  postcore_initcall(syscon_init);
  
  static void __exit syscon_exit(void)
  {
  	platform_driver_unregister(&syscon_driver);
  }
  module_exit(syscon_exit);
  
  MODULE_AUTHOR("Dong Aisheng <dong.aisheng@linaro.org>");
  MODULE_DESCRIPTION("System Control driver");
  MODULE_LICENSE("GPL v2");