From 2ac902ce17f9dfa0d4d1f0818be147b5d2515fb7 Mon Sep 17 00:00:00 2001
From: Mark Brown <broonie@opensource.wolfsonmicro.com>
Date: Wed, 19 Dec 2012 14:51:55 +0000
Subject: regmap: flat: Add flat cache type

While for I2C and SPI devices the overhead of using rbtree for devices with
only one block of registers is negligible the same isn't always going to
be true for MMIO devices where the I/O costs are very much lower. Cater
for these devices by adding a simple flat array type for them where the
lookups are simple array accesses, taking us right back to the original
ASoC cache implementation.

Thanks to Magnus Damm for the discussion which prompted this.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---
 drivers/base/regmap/Makefile        |  2 +-
 drivers/base/regmap/internal.h      |  1 +
 drivers/base/regmap/regcache-flat.c | 72 +++++++++++++++++++++++++++++++++++++
 drivers/base/regmap/regcache.c      |  1 +
 4 files changed, 75 insertions(+), 1 deletion(-)
 create mode 100644 drivers/base/regmap/regcache-flat.c

(limited to 'drivers/base')

diff --git a/drivers/base/regmap/Makefile b/drivers/base/regmap/Makefile
index 5e75d1b683e..cf129980abd 100644
--- a/drivers/base/regmap/Makefile
+++ b/drivers/base/regmap/Makefile
@@ -1,5 +1,5 @@
 obj-$(CONFIG_REGMAP) += regmap.o regcache.o
-obj-$(CONFIG_REGMAP) += regcache-rbtree.o regcache-lzo.o
+obj-$(CONFIG_REGMAP) += regcache-rbtree.o regcache-lzo.o regcache-flat.o
 obj-$(CONFIG_DEBUG_FS) += regmap-debugfs.o
 obj-$(CONFIG_REGMAP_I2C) += regmap-i2c.o
 obj-$(CONFIG_REGMAP_SPI) += regmap-spi.o
diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 401d1919635..e22bb80edff 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -177,5 +177,6 @@ int regcache_lookup_reg(struct regmap *map, unsigned int reg);
 
 extern struct regcache_ops regcache_rbtree_ops;
 extern struct regcache_ops regcache_lzo_ops;
+extern struct regcache_ops regcache_flat_ops;
 
 #endif
diff --git a/drivers/base/regmap/regcache-flat.c b/drivers/base/regmap/regcache-flat.c
new file mode 100644
index 00000000000..d9762e41959
--- /dev/null
+++ b/drivers/base/regmap/regcache-flat.c
@@ -0,0 +1,72 @@
+/*
+ * Register cache access API - flat caching support
+ *
+ * Copyright 2012 Wolfson Microelectronics plc
+ *
+ * Author: Mark Brown <broonie@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/seq_file.h>
+
+#include "internal.h"
+
+static int regcache_flat_init(struct regmap *map)
+{
+	int i;
+	unsigned int *cache;
+
+	map->cache = kzalloc(sizeof(unsigned int) * (map->max_register + 1),
+			     GFP_KERNEL);
+	if (!map->cache)
+		return -ENOMEM;
+
+	cache = map->cache;
+
+	for (i = 0; i < map->num_reg_defaults; i++)
+		cache[map->reg_defaults[i].reg] = 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;
+
+	*value = cache[reg];
+
+	return 0;
+}
+
+static int regcache_flat_write(struct regmap *map, unsigned int reg,
+			       unsigned int value)
+{
+	unsigned int *cache = map->cache;
+
+	cache[reg] = 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,
+};
diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 835883bda97..e69ff3e4742 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -22,6 +22,7 @@
 static const struct regcache_ops *cache_types[] = {
 	&regcache_rbtree_ops,
 	&regcache_lzo_ops,
+	&regcache_flat_ops,
 };
 
 static int regcache_hw_init(struct regmap *map)
-- 
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