text: /*
   * Register cache access API
   *
   * Copyright 2011 Wolfson Microelectronics plc
   *
   * Author: Dimitris Papastamos <dp@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 version 2 as
   * published by the Free Software Foundation.
   */
  
  #include <linux/slab.h>
  #include <linux/export.h>
  #include <trace/events/regmap.h>
  #include <linux/bsearch.h>
  #include <linux/sort.h>
  
  #include "internal.h"
  
  static const struct regcache_ops *cache_types[] = {
  	&regcache_rbtree_ops,
  	&regcache_lzo_ops,
  };
  
  static int regcache_hw_init(struct regmap *map)
  {
  	int i, j;
  	int ret;
  	int count;
  	unsigned int val;
  	void *tmp_buf;
  
  	if (!map->num_reg_defaults_raw)
  		return -EINVAL;
  
  	if (!map->reg_defaults_raw) {
  		dev_warn(map->dev, "No cache defaults, reading back from HW\n");
  		tmp_buf = kmalloc(map->cache_size_raw, GFP_KERNEL);
  		if (!tmp_buf)
  			return -EINVAL;
  		ret = regmap_bulk_read(map, 0, tmp_buf,
  				       map->num_reg_defaults_raw);
  		if (ret < 0) {
  			kfree(tmp_buf);
  			return ret;
  		}
  		map->reg_defaults_raw = tmp_buf;
  		map->cache_free = 1;
  	}
  
  	/* calculate the size of reg_defaults */
  	for (count = 0, i = 0; i < map->num_reg_defaults_raw; i++) {
  		val = regcache_get_val(map->reg_defaults_raw,
  				       i, map->cache_word_size);
  		if (regmap_volatile(map, i))
  			continue;
  		count++;
  	}
  
  	map->reg_defaults = kmalloc(count * sizeof(struct reg_default),
  				      GFP_KERNEL);
  	if (!map->reg_defaults) {
  		ret = -ENOMEM;
  		goto err_free;
  	}
  
  	/* fill the reg_defaults */
  	map->num_reg_defaults = count;
  	for (i = 0, j = 0; i < map->num_reg_defaults_raw; i++) {
  		val = regcache_get_val(map->reg_defaults_raw,
  				       i, map->cache_word_size);
  		if (regmap_volatile(map, i))
  			continue;
  		map->reg_defaults[j].reg = i;
  		map->reg_defaults[j].def = val;
  		j++;
  	}
  
  	return 0;
  
  err_free:
  	if (map->cache_free)
  		kfree(map->reg_defaults_raw);
  
  	return ret;
  }
  
  int regcache_init(struct regmap *map, const struct regmap_config *config)
  {
  	int ret;
  	int i;
  	void *tmp_buf;
  
  	if (map->cache_type == REGCACHE_NONE) {
  		map->cache_bypass = true;
  		return 0;
  	}
  
  	for (i = 0; i < ARRAY_SIZE(cache_types); i++)
  		if (cache_types[i]->type == map->cache_type)
  			break;
  
  	if (i == ARRAY_SIZE(cache_types)) {
  		dev_err(map->dev, "Could not match compress type: %d\n",
  			map->cache_type);
  		return -EINVAL;
  	}
  
  	map->num_reg_defaults = config->num_reg_defaults;
  	map->num_reg_defaults_raw = config->num_reg_defaults_raw;
  	map->reg_defaults_raw = config->reg_defaults_raw;
  	map->cache_word_size = DIV_ROUND_UP(config->val_bits, 8);
  	map->cache_size_raw = map->cache_word_size * config->num_reg_defaults_raw;
  
  	map->cache = NULL;
  	map->cache_ops = cache_types[i];
  
  	if (!map->cache_ops->read ||
  	    !map->cache_ops->write ||
  	    !map->cache_ops->name)
  		return -EINVAL;
  
  	/* We still need to ensure that the reg_defaults
  	 * won't vanish from under us.  We'll need to make
  	 * a copy of it.
  	 */
  	if (config->reg_defaults) {
  		if (!map->num_reg_defaults)
  			return -EINVAL;
  		tmp_buf = kmemdup(config->reg_defaults, map->num_reg_defaults *
  				  sizeof(struct reg_default), GFP_KERNEL);
  		if (!tmp_buf)
  			return -ENOMEM;
  		map->reg_defaults = tmp_buf;
  	} else if (map->num_reg_defaults_raw) {
  		/* Some devices such as PMICs don't have cache defaults,
  		 * we cope with this by reading back the HW registers and
  		 * crafting the cache defaults by hand.
  		 */
  		ret = regcache_hw_init(map);
  		if (ret < 0)
  			return ret;
  	}
  
  	if (!map->max_register)
  		map->max_register = map->num_reg_defaults_raw;
  
  	if (map->cache_ops->init) {
  		dev_dbg(map->dev, "Initializing %s cache\n",
  			map->cache_ops->name);
  		ret = map->cache_ops->init(map);
  		if (ret)
  			goto err_free;
  	}
  	return 0;
  
  err_free:
  	kfree(map->reg_defaults);
  	if (map->cache_free)
  		kfree(map->reg_defaults_raw);
  
  	return ret;
  }
  
  void regcache_exit(struct regmap *map)
  {
  	if (map->cache_type == REGCACHE_NONE)
  		return;
  
  	BUG_ON(!map->cache_ops);
  
  	kfree(map->reg_defaults);
  	if (map->cache_free)
  		kfree(map->reg_defaults_raw);
  
  	if (map->cache_ops->exit) {
  		dev_dbg(map->dev, "Destroying %s cache\n",
  			map->cache_ops->name);
  		map->cache_ops->exit(map);
  	}
  }
  
  /**
   * regcache_read: Fetch the value of a given register from the cache.
   *
   * @map: map to configure.
   * @reg: The register index.
   * @value: The value to be returned.
   *
   * Return a negative value on failure, 0 on success.
   */
  int regcache_read(struct regmap *map,
  		  unsigned int reg, unsigned int *value)
  {
  	int ret;
  
  	if (map->cache_type == REGCACHE_NONE)
  		return -ENOSYS;
  
  	BUG_ON(!map->cache_ops);
  
  	if (!regmap_volatile(map, reg)) {
  		ret = map->cache_ops->read(map, reg, value);
  
  		if (ret == 0)
  			trace_regmap_reg_read_cache(map->dev, reg, *value);
  
  		return ret;
  	}
  
  	return -EINVAL;
  }
  EXPORT_SYMBOL_GPL(regcache_read);
  
  /**
   * regcache_write: Set the value of a given register in the cache.
   *
   * @map: map to configure.
   * @reg: The register index.
   * @value: The new register value.
   *
   * Return a negative value on failure, 0 on success.
   */
  int regcache_write(struct regmap *map,
  		   unsigned int reg, unsigned int value)
  {
  	if (map->cache_type == REGCACHE_NONE)
  		return 0;
  
  	BUG_ON(!map->cache_ops);
  
  	if (!regmap_writeable(map, reg))
  		return -EIO;
  
  	if (!regmap_volatile(map, reg))
  		return map->cache_ops->write(map, reg, value);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(regcache_write);
  
  /**
   * regcache_sync: Sync the register cache with the hardware.
   *
   * @map: map to configure.
   *
   * Any registers that should not be synced should be marked as
   * volatile.  In general drivers can choose not to use the provided
   * syncing functionality if they so require.
   *
   * Return a negative value on failure, 0 on success.
   */
  int regcache_sync(struct regmap *map)
  {
  	int ret = 0;
  	unsigned int val;
  	unsigned int i;
  	const char *name;
  	unsigned int bypass;
  
  	BUG_ON(!map->cache_ops);
  
  	mutex_lock(&map->lock);
  	/* Remember the initial bypass state */
  	bypass = map->cache_bypass;
  	dev_dbg(map->dev, "Syncing %s cache\n",
  		map->cache_ops->name);
  	name = map->cache_ops->name;
  	trace_regcache_sync(map->dev, name, "start");
  	if (!map->cache_dirty)
  		goto out;
  	if (map->cache_ops->sync) {
  		ret = map->cache_ops->sync(map);
  	} else {
  		for (i = 0; i < map->num_reg_defaults; i++) {
  			ret = regcache_read(map, i, &val);
  			if (ret < 0)
  				goto out;
  			map->cache_bypass = 1;
  			ret = _regmap_write(map, i, val);
  			map->cache_bypass = 0;
  			if (ret < 0)
  				goto out;
  			dev_dbg(map->dev, "Synced register %#x, value %#x\n",
  				map->reg_defaults[i].reg,
  				map->reg_defaults[i].def);
  		}
  
  	}
  out:
  	trace_regcache_sync(map->dev, name, "stop");
  	/* Restore the bypass state */
  	map->cache_bypass = bypass;
  	mutex_unlock(&map->lock);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(regcache_sync);
  
  /**
   * regcache_cache_only: Put a register map into cache only mode
   *
   * @map: map to configure
   * @cache_only: flag if changes should be written to the hardware
   *
   * When a register map is marked as cache only writes to the register
   * map API will only update the register cache, they will not cause
   * any hardware changes.  This is useful for allowing portions of
   * drivers to act as though the device were functioning as normal when
   * it is disabled for power saving reasons.
   */
  void regcache_cache_only(struct regmap *map, bool enable)
  {
  	mutex_lock(&map->lock);
  	WARN_ON(map->cache_bypass && enable);
  	map->cache_only = enable;
  	mutex_unlock(&map->lock);
  }
  EXPORT_SYMBOL_GPL(regcache_cache_only);
  
  /**
   * regcache_mark_dirty: Mark the register cache as dirty
   *
   * @map: map to mark
   *
   * Mark the register cache as dirty, for example due to the device
   * having been powered down for suspend.  If the cache is not marked
   * as dirty then the cache sync will be suppressed.
   */
  void regcache_mark_dirty(struct regmap *map)
  {
  	mutex_lock(&map->lock);
  	map->cache_dirty = true;
  	mutex_unlock(&map->lock);
  }
  EXPORT_SYMBOL_GPL(regcache_mark_dirty);
  
  /**
   * regcache_cache_bypass: Put a register map into cache bypass mode
   *
   * @map: map to configure
   * @cache_bypass: flag if changes should not be written to the hardware
   *
   * When a register map is marked with the cache bypass option, writes
   * to the register map API will only update the hardware and not the
   * the cache directly.  This is useful when syncing the cache back to
   * the hardware.
   */
  void regcache_cache_bypass(struct regmap *map, bool enable)
  {
  	mutex_lock(&map->lock);
  	WARN_ON(map->cache_only && enable);
  	map->cache_bypass = enable;
  	mutex_unlock(&map->lock);
  }
  EXPORT_SYMBOL_GPL(regcache_cache_bypass);
  
  bool regcache_set_val(void *base, unsigned int idx,
  		      unsigned int val, unsigned int word_size)
  {
  	switch (word_size) {
  	case 1: {
  		u8 *cache = base;
  		if (cache[idx] == val)
  			return true;
  		cache[idx] = val;
  		break;
  	}
  	case 2: {
  		u16 *cache = base;
  		if (cache[idx] == val)
  			return true;
  		cache[idx] = val;
  		break;
  	}
  	default:
  		BUG();
  	}
  	/* unreachable */
  	return false;
  }
  
  unsigned int regcache_get_val(const void *base, unsigned int idx,
  			      unsigned int word_size)
  {
  	if (!base)
  		return -EINVAL;
  
  	switch (word_size) {
  	case 1: {
  		const u8 *cache = base;
  		return cache[idx];
  	}
  	case 2: {
  		const u16 *cache = base;
  		return cache[idx];
  	}
  	default:
  		BUG();
  	}
  	/* unreachable */
  	return -1;
  }
  
  static int regcache_default_cmp(const void *a, const void *b)
  {
  	const struct reg_default *_a = a;
  	const struct reg_default *_b = b;
  
  	return _a->reg - _b->reg;
  }
  
  int regcache_lookup_reg(struct regmap *map, unsigned int reg)
  {
  	struct reg_default key;
  	struct reg_default *r;
  
  	key.reg = reg;
  	key.def = 0;
  
  	r = bsearch(&key, map->reg_defaults, map->num_reg_defaults,
  		    sizeof(struct reg_default), regcache_default_cmp);
  
  	if (r)
  		return r - map->reg_defaults;
  	else
  		return -ENOENT;
  }
  