text: // SPDX-License-Identifier: GPL-2.0
  //
  // Register cache access API - flat caching support
  //
  // Copyright 2012 Wolfson Microelectronics plc
  //
  // Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
  
  #include <linux/device.h>
  #include <linux/seq_file.h>
  #include <linux/slab.h>
  
  #include "internal.h"
  
  static inline unsigned int regcache_flat_get_index(const struct regmap *map,
  						   unsigned int reg)
  {
  	return regcache_get_index_by_order(map, reg);
  }
  
  static int regcache_flat_init(struct regmap *map)
  {
  	int i;
  	unsigned int *cache;
  
  	if (!map || map->reg_stride_order < 0 || !map->max_register)
  		return -EINVAL;
  
  	map->cache = kcalloc(regcache_flat_get_index(map, map->max_register)
  			     + 1, sizeof(unsigned int), GFP_KERNEL);
  	if (!map->cache)
  		return -ENOMEM;
  
  	cache = map->cache;
  
  	for (i = 0; i < map->num_reg_defaults; i++) {
  		unsigned int reg = map->reg_defaults[i].reg;
  		unsigned int index = regcache_flat_get_index(map, reg);
  
  		cache[index] = map->reg_defaults[i].def;
  	}
  
  	return 0;
  }
  
  static int regcache_flat_exit(struct regmap *map)
  {
  	kfree(map->cache);
  	map->cache = NULL;
  
  	return 0;
  }
  
  static int regcache_flat_read(struct regmap *map,
  			      unsigned int reg, unsigned int *value)
  {
  	unsigned int *cache = map->cache;
  	unsigned int index = regcache_flat_get_index(map, reg);
  
  	*value = cache[index];
  
  	return 0;
  }
  
  static int regcache_flat_write(struct regmap *map, unsigned int reg,
  			       unsigned int value)
  {
  	unsigned int *cache = map->cache;
  	unsigned int index = regcache_flat_get_index(map, reg);
  
  	cache[index] = value;
  
  	return 0;
  }
  
  struct regcache_ops regcache_flat_ops = {
  	.type = REGCACHE_FLAT,
  	.name = "flat",
  	.init = regcache_flat_init,
  	.exit = regcache_flat_exit,
  	.read = regcache_flat_read,
  	.write = regcache_flat_write,
  };
  