drivers/base/regmap/regcache.c - kernel/msm-4.19 - Gitiles

 /*
  * 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 <linux/device.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) {
 		u32 cache_bypass = map->cache_bypass;
 		dev_warn(map->dev, "No cache defaults, reading back from HW\n");

 		/* Bypass the cache access till data read from HW*/
 		map->cache_bypass = 1;
 		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);
 		map->cache_bypass = cache_bypass;
 		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;
 }

 /**
  * 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;
 }

 /**
  * 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 i;
 	const char *name;
 	unsigned int bypass;

 	BUG_ON(!map->cache_ops || !map->cache_ops->sync);

 	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;

 	/* Apply any patch first */
 	map->cache_bypass = 1;
 	for (i = 0; i < map->patch_regs; i++) {
 		ret = _regmap_write(map, map->patch[i].reg, map->patch[i].def);
 		if (ret != 0) {
 			dev_err(map->dev, "Failed to write %x = %x: %d\n",
 				map->patch[i].reg, map->patch[i].def, ret);
 			goto out;
 		}
 	}
 	map->cache_bypass = 0;

 	ret = map->cache_ops->sync(map, 0, map->max_register);

 	if (ret == 0)
 		map->cache_dirty = false;

 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_sync_region: Sync part  of the register cache with the hardware.
  *
  * @map: map to sync.
  * @min: first register to sync
  * @max: last register to sync
  *
  * Write all non-default register values in the specified region to
  * the hardware.
  *
  * Return a negative value on failure, 0 on success.
  */
 int regcache_sync_region(struct regmap *map, unsigned int min,
 			 unsigned int max)
 {
 	int ret = 0;
 	const char *name;
 	unsigned int bypass;

 	BUG_ON(!map->cache_ops || !map->cache_ops->sync);

 	mutex_lock(&map->lock);

 	/* Remember the initial bypass state */
 	bypass = map->cache_bypass;

 	name = map->cache_ops->name;
 	dev_dbg(map->dev, "Syncing %s cache from %d-%d\n", name, min, max);

 	trace_regcache_sync(map->dev, name, "start region");

 	if (!map->cache_dirty)
 		goto out;

 	ret = map->cache_ops->sync(map, min, max);

 out:
 	trace_regcache_sync(map->dev, name, "stop region");
 	/* Restore the bypass state */
 	map->cache_bypass = bypass;
 	mutex_unlock(&map->lock);

 	return ret;
 }
 EXPORT_SYMBOL_GPL(regcache_sync_region);

 /**
  * 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;
 	trace_regmap_cache_only(map->dev, 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;
 	trace_regmap_cache_bypass(map->dev, 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;
 	}
 	case 4: {
 		u32 *cache = base;
 		if (cache[idx] == val)
 			return true;
 		cache[idx] = val;
 		break;
 	}
 	default:
 		BUG();
 	}
 	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];
 	}
 	case 4: {
 		const u32 *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;
 }
	/*
	* 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 <linux/device.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) {
	u32 cache_bypass = map->cache_bypass;
	dev_warn(map->dev, "No cache defaults, reading back from HW\n");

	/* Bypass the cache access till data read from HW*/
	map->cache_bypass = 1;
	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);
	map->cache_bypass = cache_bypass;
	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;
	}

	/**
	* 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;
	}

	/**
	* 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 i;
	const char *name;
	unsigned int bypass;

	BUG_ON(!map->cache_ops \|\| !map->cache_ops->sync);

	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;

	/* Apply any patch first */
	map->cache_bypass = 1;
	for (i = 0; i < map->patch_regs; i++) {
	ret = _regmap_write(map, map->patch[i].reg, map->patch[i].def);
	if (ret != 0) {
	dev_err(map->dev, "Failed to write %x = %x: %d\n",
	map->patch[i].reg, map->patch[i].def, ret);
	goto out;
	}
	}
	map->cache_bypass = 0;

	ret = map->cache_ops->sync(map, 0, map->max_register);

	if (ret == 0)
	map->cache_dirty = false;

	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_sync_region: Sync part of the register cache with the hardware.
	*
	* @map: map to sync.
	* @min: first register to sync
	* @max: last register to sync
	*
	* Write all non-default register values in the specified region to
	* the hardware.
	*
	* Return a negative value on failure, 0 on success.
	*/
	int regcache_sync_region(struct regmap *map, unsigned int min,
	unsigned int max)
	{
	int ret = 0;
	const char *name;
	unsigned int bypass;

	BUG_ON(!map->cache_ops \|\| !map->cache_ops->sync);

	mutex_lock(&map->lock);

	/* Remember the initial bypass state */
	bypass = map->cache_bypass;

	name = map->cache_ops->name;
	dev_dbg(map->dev, "Syncing %s cache from %d-%d\n", name, min, max);

	trace_regcache_sync(map->dev, name, "start region");

	if (!map->cache_dirty)
	goto out;

	ret = map->cache_ops->sync(map, min, max);

	out:
	trace_regcache_sync(map->dev, name, "stop region");
	/* Restore the bypass state */
	map->cache_bypass = bypass;
	mutex_unlock(&map->lock);

	return ret;
	}
	EXPORT_SYMBOL_GPL(regcache_sync_region);

	/**
	* 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;
	trace_regmap_cache_only(map->dev, 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;
	trace_regmap_cache_bypass(map->dev, 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;
	}
	case 4: {
	u32 *cache = base;
	if (cache[idx] == val)
	return true;
	cache[idx] = val;
	break;
	}
	default:
	BUG();
	}
	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];
	}
	case 4: {
	const u32 *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;
	}