regmap: Removed compressed cache support

The compressed register cache support has assumptions that make it hard to
cover in testing, mainly that it requires raw registers defaults be
provided. Rather than either address these assumptions or leave it untested
by the forthcoming KUnit tests let's remove it, the use case is quite thin
and there are no current users.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230324-regcache-lzo-v1-1-08c5d63e2a5e@kernel.org

drivers/base/regmap/Kconfig

@@ -9,11 +9,6 @@ config REGMAP
 	select MDIO_BUS if REGMAP_MDIO
 	bool
 
-config REGCACHE_COMPRESSED
-	select LZO_COMPRESS
-	select LZO_DECOMPRESS
-	bool
-
 config REGMAP_AC97
 	tristate
 

drivers/base/regmap/Makefile

@@ -4,7 +4,6 @@ CFLAGS_regmap.o := -I$(src)
 
 obj-$(CONFIG_REGMAP) += regmap.o regcache.o
 obj-$(CONFIG_REGMAP) += regcache-rbtree.o regcache-flat.o
-obj-$(CONFIG_REGCACHE_COMPRESSED) += regcache-lzo.o
 obj-$(CONFIG_DEBUG_FS) += regmap-debugfs.o
 obj-$(CONFIG_REGMAP_AC97) += regmap-ac97.o
 obj-$(CONFIG_REGMAP_I2C) += regmap-i2c.o

drivers/base/regmap/internal.h

@@ -281,7 +281,6 @@ enum regmap_endian regmap_get_val_endian(struct device *dev,
 					 const struct regmap_config *config);
 
 extern struct regcache_ops regcache_rbtree_ops;
-extern struct regcache_ops regcache_lzo_ops;
 extern struct regcache_ops regcache_flat_ops;
 
 static inline const char *regmap_name(const struct regmap *map)

drivers/base/regmap/regcache-lzo.c

-// SPDX-License-Identifier: GPL-2.0
-//
-// Register cache access API - LZO caching support
-//
-// Copyright 2011 Wolfson Microelectronics plc
-//
-// Author: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
-
-#include <linux/device.h>
-#include <linux/lzo.h>
-#include <linux/slab.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 = kcalloc(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 = bitmap_zalloc(bmp_size, GFP_KERNEL);
-	if (!sync_bmp) {
-		ret = -ENOMEM;
-		goto err;
-	}
-
-	/* 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]) {
-			bitmap_free(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])
-		bitmap_free(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 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);
-	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 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);
-	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 = true;
-		ret = _regmap_write(map, i, val);
-		map->cache_bypass = false;
-		if (ret)
-			return ret;
-		dev_dbg(map->dev, "Synced register %#x, value %#x\n",
-			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
-};

drivers/base/regmap/regcache.c

@@ -17,9 +17,6 @@
 
 static const struct regcache_ops *cache_types[] = {
 	&regcache_rbtree_ops,
-#if IS_ENABLED(CONFIG_REGCACHE_COMPRESSED)
-	&regcache_lzo_ops,
-#endif
 	&regcache_flat_ops,
 };
 

include/linux/regmap.h

@@ -50,7 +50,6 @@ struct sdw_slave;
 enum regcache_type {
 	REGCACHE_NONE,
 	REGCACHE_RBTREE,
-	REGCACHE_COMPRESSED,
 	REGCACHE_FLAT,
 };