/*
   * Register cache access API - LZO caching support
   *
   * 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/device.h>
  #include <linux/lzo.h>
  
  #include "internal.h"
  
  static int regcache_lzo_exit(struct regmap *map);
  
  struct regcache_lzo_ctx {
  	void *wmem;
  	void *dst;
  	const void *src;
  	size_t src_len;
  	size_t dst_len;
  	size_t decompressed_size;
  	unsigned long *sync_bmp;
  	int sync_bmp_nbits;
  };
  
  #define LZO_BLOCK_NUM 8
  static int regcache_lzo_block_count(struct regmap *map)
  {
  	return LZO_BLOCK_NUM;
  }
  
  static int regcache_lzo_prepare(struct regcache_lzo_ctx *lzo_ctx)
  {
  	lzo_ctx->wmem = kmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
  	if (!lzo_ctx->wmem)
  		return -ENOMEM;
  	return 0;
  }
  
  static int regcache_lzo_compress(struct regcache_lzo_ctx *lzo_ctx)
  {
  	size_t compress_size;
  	int ret;
  
  	ret = lzo1x_1_compress(lzo_ctx->src, lzo_ctx->src_len,
  			       lzo_ctx->dst, &compress_size, lzo_ctx->wmem);
  	if (ret != LZO_E_OK || compress_size > lzo_ctx->dst_len)
  		return -EINVAL;
  	lzo_ctx->dst_len = compress_size;
  	return 0;
  }
  
  static int regcache_lzo_decompress(struct regcache_lzo_ctx *lzo_ctx)
  {
  	size_t dst_len;
  	int ret;
  
  	dst_len = lzo_ctx->dst_len;
  	ret = lzo1x_decompress_safe(lzo_ctx->src, lzo_ctx->src_len,
  				    lzo_ctx->dst, &dst_len);
  	if (ret != LZO_E_OK || dst_len != lzo_ctx->dst_len)
  		return -EINVAL;
  	return 0;
  }
  
  static int regcache_lzo_compress_cache_block(struct regmap *map,
  		struct regcache_lzo_ctx *lzo_ctx)
  {
  	int ret;
  
  	lzo_ctx->dst_len = lzo1x_worst_compress(PAGE_SIZE);
  	lzo_ctx->dst = kmalloc(lzo_ctx->dst_len, GFP_KERNEL);
  	if (!lzo_ctx->dst) {
  		lzo_ctx->dst_len = 0;
  		return -ENOMEM;
  	}
  
  	ret = regcache_lzo_compress(lzo_ctx);
  	if (ret < 0)
  		return ret;
  	return 0;
  }
  
  static int regcache_lzo_decompress_cache_block(struct regmap *map,
  		struct regcache_lzo_ctx *lzo_ctx)
  {
  	int ret;
  
  	lzo_ctx->dst_len = lzo_ctx->decompressed_size;
  	lzo_ctx->dst = kmalloc(lzo_ctx->dst_len, GFP_KERNEL);
  	if (!lzo_ctx->dst) {
  		lzo_ctx->dst_len = 0;
  		return -ENOMEM;
  	}
  
  	ret = regcache_lzo_decompress(lzo_ctx);
  	if (ret < 0)
  		return ret;
  	return 0;
  }
  
  static inline int regcache_lzo_get_blkindex(struct regmap *map,
  					    unsigned int reg)
  {
  	return ((reg / map->reg_stride) * map->cache_word_size) /
  		DIV_ROUND_UP(map->cache_size_raw,
  			     regcache_lzo_block_count(map));
  }
  
  static inline int regcache_lzo_get_blkpos(struct regmap *map,
  					  unsigned int reg)
  {
  	return (reg / map->reg_stride) %
  		    (DIV_ROUND_UP(map->cache_size_raw,
  				  regcache_lzo_block_count(map)) /
  		     map->cache_word_size);
  }
  
  static inline int regcache_lzo_get_blksize(struct regmap *map)
  {
  	return DIV_ROUND_UP(map->cache_size_raw,
  			    regcache_lzo_block_count(map));
  }
  
  static int regcache_lzo_init(struct regmap *map)
  {
  	struct regcache_lzo_ctx **lzo_blocks;
  	size_t bmp_size;
  	int ret, i, blksize, blkcount;
  	const char *p, *end;
  	unsigned long *sync_bmp;
  
  	ret = 0;
  
  	blkcount = regcache_lzo_block_count(map);
  	map->cache = kzalloc(blkcount * sizeof *lzo_blocks,
  			     GFP_KERNEL);
  	if (!map->cache)
  		return -ENOMEM;
  	lzo_blocks = map->cache;
  
  	/*
  	 * allocate a bitmap to be used when syncing the cache with
  	 * the hardware.  Each time a register is modified, the corresponding
  	 * bit is set in the bitmap, so we know that we have to sync
  	 * that register.
  	 */
  	bmp_size = map->num_reg_defaults_raw;
  	sync_bmp = kmalloc(BITS_TO_LONGS(bmp_size) * sizeof(long),
  			   GFP_KERNEL);
  	if (!sync_bmp) {
  		ret = -ENOMEM;
  		goto err;
  	}
  	bitmap_zero(sync_bmp, bmp_size);
  
  	/* allocate the lzo blocks and initialize them */
  	for (i = 0; i < blkcount; i++) {
  		lzo_blocks[i] = kzalloc(sizeof **lzo_blocks,
  					GFP_KERNEL);
  		if (!lzo_blocks[i]) {
  			kfree(sync_bmp);
  			ret = -ENOMEM;
  			goto err;
  		}
  		lzo_blocks[i]->sync_bmp = sync_bmp;
  		lzo_blocks[i]->sync_bmp_nbits = bmp_size;
  		/* alloc the working space for the compressed block */
  		ret = regcache_lzo_prepare(lzo_blocks[i]);
  		if (ret < 0)
  			goto err;
  	}
  
  	blksize = regcache_lzo_get_blksize(map);
  	p = map->reg_defaults_raw;
  	end = map->reg_defaults_raw + map->cache_size_raw;
  	/* compress the register map and fill the lzo blocks */
  	for (i = 0; i < blkcount; i++, p += blksize) {
  		lzo_blocks[i]->src = p;
  		if (p + blksize > end)
  			lzo_blocks[i]->src_len = end - p;
  		else
  			lzo_blocks[i]->src_len = blksize;
  		ret = regcache_lzo_compress_cache_block(map,
  						       lzo_blocks[i]);
  		if (ret < 0)
  			goto err;
  		lzo_blocks[i]->decompressed_size =
  			lzo_blocks[i]->src_len;
  	}
  
  	return 0;
  err:
  	regcache_lzo_exit(map);
  	return ret;
  }
  
  static int regcache_lzo_exit(struct regmap *map)
  {
  	struct regcache_lzo_ctx **lzo_blocks;
  	int i, blkcount;
  
  	lzo_blocks = map->cache;
  	if (!lzo_blocks)
  		return 0;
  
  	blkcount = regcache_lzo_block_count(map);
  	/*
  	 * the pointer to the bitmap used for syncing the cache
  	 * is shared amongst all lzo_blocks.  Ensure it is freed
  	 * only once.
  	 */
  	if (lzo_blocks[0])
  		kfree(lzo_blocks[0]->sync_bmp);
  	for (i = 0; i < blkcount; i++) {
  		if (lzo_blocks[i]) {
  			kfree(lzo_blocks[i]->wmem);
  			kfree(lzo_blocks[i]->dst);
  		}
  		/* each lzo_block is a pointer returned by kmalloc or NULL */
  		kfree(lzo_blocks[i]);
  	}
  	kfree(lzo_blocks);
  	map->cache = NULL;
  	return 0;
  }
  
  static int regcache_lzo_read(struct regmap *map,
  			     unsigned int reg, unsigned int *value)
  {
  	struct regcache_lzo_ctx *lzo_block, **lzo_blocks;
  	int ret, blkindex, blkpos;
  	size_t blksize, tmp_dst_len;
  	void *tmp_dst;
  
  	/* index of the compressed lzo block */
  	blkindex = regcache_lzo_get_blkindex(map, reg);
  	/* register index within the decompressed block */
  	blkpos = regcache_lzo_get_blkpos(map, reg);
  	/* size of the compressed block */
  	blksize = regcache_lzo_get_blksize(map);
  	lzo_blocks = map->cache;
  	lzo_block = lzo_blocks[blkindex];
  
  	/* save the pointer and length of the compressed block */
  	tmp_dst = lzo_block->dst;
  	tmp_dst_len = lzo_block->dst_len;
  
  	/* prepare the source to be the compressed block */
  	lzo_block->src = lzo_block->dst;
  	lzo_block->src_len = lzo_block->dst_len;
  
  	/* decompress the block */
  	ret = regcache_lzo_decompress_cache_block(map, lzo_block);
  	if (ret >= 0)
  		/* fetch the value from the cache */
  		*value = regcache_get_val(map, lzo_block->dst, blkpos);
  
  	kfree(lzo_block->dst);
  	/* restore the pointer and length of the compressed block */
  	lzo_block->dst = tmp_dst;
  	lzo_block->dst_len = tmp_dst_len;
  
  	return ret;
  }
  
  static int regcache_lzo_write(struct regmap *map,
  			      unsigned int reg, unsigned int value)
  {
  	struct regcache_lzo_ctx *lzo_block, **lzo_blocks;
  	int ret, blkindex, blkpos;
  	size_t blksize, tmp_dst_len;
  	void *tmp_dst;
  
  	/* index of the compressed lzo block */
  	blkindex = regcache_lzo_get_blkindex(map, reg);
  	/* register index within the decompressed block */
  	blkpos = regcache_lzo_get_blkpos(map, reg);
  	/* size of the compressed block */
  	blksize = regcache_lzo_get_blksize(map);
  	lzo_blocks = map->cache;
  	lzo_block = lzo_blocks[blkindex];
  
  	/* save the pointer and length of the compressed block */
  	tmp_dst = lzo_block->dst;
  	tmp_dst_len = lzo_block->dst_len;
  
  	/* prepare the source to be the compressed block */
  	lzo_block->src = lzo_block->dst;
  	lzo_block->src_len = lzo_block->dst_len;
  
  	/* decompress the block */
  	ret = regcache_lzo_decompress_cache_block(map, lzo_block);
  	if (ret < 0) {
  		kfree(lzo_block->dst);
  		goto out;
  	}
  
  	/* write the new value to the cache */
  	if (regcache_set_val(map, lzo_block->dst, blkpos, value)) {
  		kfree(lzo_block->dst);
  		goto out;
  	}
  
  	/* prepare the source to be the decompressed block */
  	lzo_block->src = lzo_block->dst;
  	lzo_block->src_len = lzo_block->dst_len;
  
  	/* compress the block */
  	ret = regcache_lzo_compress_cache_block(map, lzo_block);
  	if (ret < 0) {
  		kfree(lzo_block->dst);
  		kfree(lzo_block->src);
  		goto out;
  	}
  
  	/* set the bit so we know we have to sync this register */
  	set_bit(reg / map->reg_stride, lzo_block->sync_bmp);
  	kfree(tmp_dst);
  	kfree(lzo_block->src);
  	return 0;
  out:
  	lzo_block->dst = tmp_dst;
  	lzo_block->dst_len = tmp_dst_len;
  	return ret;
  }
  
  static int regcache_lzo_sync(struct regmap *map, unsigned int min,
  			     unsigned int max)
  {
  	struct regcache_lzo_ctx **lzo_blocks;
  	unsigned int val;
  	int i;
  	int ret;
  
  	lzo_blocks = map->cache;
  	i = min;
  	for_each_set_bit_from(i, lzo_blocks[0]->sync_bmp,
  			      lzo_blocks[0]->sync_bmp_nbits) {
  		if (i > max)
  			continue;
  
  		ret = regcache_read(map, i, &val);
  		if (ret)
  			return ret;
  
  		/* Is this the hardware default?  If so skip. */
  		ret = regcache_lookup_reg(map, i);
  		if (ret > 0 && val == map->reg_defaults[ret].def)
  			continue;
  
  		map->cache_bypass = 1;
  		ret = _regmap_write(map, i, val);
  		map->cache_bypass = 0;
  		if (ret)
  			return ret;
  		dev_dbg(map->dev, "Synced register %#x, value %#x
  ",
  			i, val);
  	}
  
  	return 0;
  }
  
  struct regcache_ops regcache_lzo_ops = {
  	.type = REGCACHE_COMPRESSED,
  	.name = "lzo",
  	.init = regcache_lzo_init,
  	.exit = regcache_lzo_exit,
  	.read = regcache_lzo_read,
  	.write = regcache_lzo_write,
  	.sync = regcache_lzo_sync
  };