regmap: make LZO cache optional

Commit 2cbbb579 ("regmap: Add the LZO cache support") added support
for LZO compression in regcache, but there were never any users added
afterwards. Since LZO support itself has its own size, it currently is
rather a deoptimization.

So make it optional by introducing a symbol that can be selected by
drivers wanting to make use of it.

Saves e.g. ~46 kB on MIPS (size of LZO support + regcache LZO code).
Signed-off-by: NJonas Gorski <jonas.gorski@gmail.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

drivers/base/regmap/Kconfig

@@ -4,9 +4,12 @@
 
 config REGMAP
 	default y if (REGMAP_I2C || REGMAP_SPI || REGMAP_SPMI || REGMAP_AC97 || REGMAP_MMIO || REGMAP_IRQ)
+	select IRQ_DOMAIN if REGMAP_IRQ
+	bool
+
+config REGCACHE_COMPRESSED
 	select LZO_COMPRESS
 	select LZO_DECOMPRESS
-	select IRQ_DOMAIN if REGMAP_IRQ
 	bool
 
 config REGMAP_AC97

drivers/base/regmap/Makefile

@@ -2,7 +2,8 @@
 CFLAGS_regmap.o := -I$(src)
 
 obj-$(CONFIG_REGMAP) += regmap.o regcache.o
-obj-$(CONFIG_REGMAP) += regcache-rbtree.o regcache-lzo.o regcache-flat.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/regcache.c

@@ -21,7 +21,9 @@
 
 static const struct regcache_ops *cache_types[] = {
 	&regcache_rbtree_ops,
+#if IS_ENABLED(CONFIG_REGCHACHE_COMPRESSED)
 	&regcache_lzo_ops,
+#endif
 	&regcache_flat_ops,
 };