regmap: introduce fast_io busses, and use a spinlock for them

Some bus types have very fast IO. For these, acquiring a mutex for every
IO operation is a significant overhead. Allow busses to indicate their IO
is fast, and enhance regmap to use a spinlock for those busses.

[Currently limited to native endian registers -- broonie]

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
(cherry picked from commit bacdbe077342ecc9e7b3e374cc5a41995116706a)

Change-Id: I337f27a09f2b176b46e8f6d05401957a1abc0609
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-on: http://git-master/r/96503
Reviewed-by: Simone Willett <swillett@nvidia.com>
Tested-by: Simone Willett <swillett@nvidia.com>

4 files changed, 66 insertions, 32 deletions

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 4f87633d56e9..44e3b1c438f4 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -31,8 +31,14 @@ struct regmap_format {
 	unsigned int (*parse_val)(void *buf);
 };
 
+typedef void (*regmap_lock)(struct regmap *map);
+typedef void (*regmap_unlock)(struct regmap *map);
+
 struct regmap {
-	struct mutex lock;
+	struct mutex mutex;
+	spinlock_t spinlock;
+	regmap_lock lock;
+	regmap_unlock unlock;
 
 	struct device *dev; /* Device we do I/O on */
 	void *work_buf;     /* Scratch buffer used to format I/O */
diff --git a/drivers/base/regmap/regcache-rbtree.c b/drivers/base/regmap/regcache-rbtree.c
index acdc1d443b2e..e3aa1fc69473 100644
--- a/drivers/base/regmap/regcache-rbtree.c
+++ b/drivers/base/regmap/regcache-rbtree.c
@@ -139,7 +139,7 @@ static int rbtree_show(struct seq_file *s, void *ignored)
 	int registers = 0;
 	int average;
 
-	mutex_lock(&map->lock);
+	map->lock(map);
 
 	for (node = rb_first(&rbtree_ctx->root); node != NULL;
 	     node = rb_next(node)) {
@@ -160,7 +160,7 @@ static int rbtree_show(struct seq_file *s, void *ignored)
 	seq_printf(s, "%d nodes, %d registers, average %d registers\n",
 		   nodes, registers, average);
 
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 
 	return 0;
 }
diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 4c8c745f75a4..d80e2dd4374b 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -262,7 +262,7 @@ int regcache_sync(struct regmap *map)
 
 	BUG_ON(!map->cache_ops || !map->cache_ops->sync);
 
-	mutex_lock(&map->lock);
+	map->lock(map);
 	/* Remember the initial bypass state */
 	bypass = map->cache_bypass;
 	dev_dbg(map->dev, "Syncing %s cache\n",
@@ -294,7 +294,7 @@ out:
 	trace_regcache_sync(map->dev, name, "stop");
 	/* Restore the bypass state */
 	map->cache_bypass = bypass;
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 
 	return ret;
 }
@@ -321,7 +321,7 @@ int regcache_sync_region(struct regmap *map, unsigned int min,
 
 	BUG_ON(!map->cache_ops || !map->cache_ops->sync);
 
-	mutex_lock(&map->lock);
+	map->lock(map);
 
 	/* Remember the initial bypass state */
 	bypass = map->cache_bypass;
@@ -340,7 +340,7 @@ out:
 	trace_regcache_sync(map->dev, name, "stop region");
 	/* Restore the bypass state */
 	map->cache_bypass = bypass;
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 
 	return ret;
 }
@@ -360,11 +360,11 @@ EXPORT_SYMBOL_GPL(regcache_sync_region);
  */
 void regcache_cache_only(struct regmap *map, bool enable)
 {
-	mutex_lock(&map->lock);
+	map->lock(map);
 	WARN_ON(map->cache_bypass && enable);
 	map->cache_only = enable;
 	trace_regmap_cache_only(map->dev, enable);
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 }
 EXPORT_SYMBOL_GPL(regcache_cache_only);
 
@@ -379,9 +379,9 @@ EXPORT_SYMBOL_GPL(regcache_cache_only);
  */
 void regcache_mark_dirty(struct regmap *map)
 {
-	mutex_lock(&map->lock);
+	map->lock(map);
 	map->cache_dirty = true;
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 }
 EXPORT_SYMBOL_GPL(regcache_mark_dirty);
 
@@ -398,11 +398,11 @@ EXPORT_SYMBOL_GPL(regcache_mark_dirty);
  */
 void regcache_cache_bypass(struct regmap *map, bool enable)
 {
-	mutex_lock(&map->lock);
+	map->lock(map);
 	WARN_ON(map->cache_only && enable);
 	map->cache_bypass = enable;
 	trace_regmap_cache_bypass(map->dev, enable);
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 }
 EXPORT_SYMBOL_GPL(regcache_cache_bypass);
 
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index f4a2ab26d8be..1af922301ec0 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -179,6 +179,26 @@ static unsigned int regmap_parse_32(void *buf)
 	return b[0];
 }
 
+static void regmap_lock_mutex(struct regmap *map)
+{
+	mutex_lock(&map->mutex);
+}
+
+static void regmap_unlock_mutex(struct regmap *map)
+{
+	mutex_unlock(&map->mutex);
+}
+
+static void regmap_lock_spinlock(struct regmap *map)
+{
+	spin_lock(&map->spinlock);
+}
+
+static void regmap_unlock_spinlock(struct regmap *map)
+{
+	spin_unlock(&map->spinlock);
+}
+
 /**
  * regmap_init(): Initialise register map
  *
@@ -208,7 +228,15 @@ struct regmap *regmap_init(struct device *dev,
 		goto err;
 	}
 
-	mutex_init(&map->lock);
+	if (bus->fast_io) {
+		spin_lock_init(&map->spinlock);
+		map->lock = regmap_lock_spinlock;
+		map->unlock = regmap_unlock_spinlock;
+	} else {
+		mutex_init(&map->mutex);
+		map->lock = regmap_lock_mutex;
+		map->unlock = regmap_unlock_mutex;
+	}
 	map->format.buf_size = (config->reg_bits + config->val_bits) / 8;
 	map->format.reg_bytes = DIV_ROUND_UP(config->reg_bits, 8);
 	map->format.pad_bytes = config->pad_bits / 8;
@@ -391,7 +419,7 @@ int regmap_reinit_cache(struct regmap *map, const struct regmap_config *config)
 {
 	int ret;
 
-	mutex_lock(&map->lock);
+	map->lock(map);
 
 	regcache_exit(map);
 	regmap_debugfs_exit(map);
@@ -409,7 +437,7 @@ int regmap_reinit_cache(struct regmap *map, const struct regmap_config *config)
 
 	ret = regcache_init(map, config);
 
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 
 	return ret;
 }
@@ -561,11 +589,11 @@ int regmap_write(struct regmap *map, unsigned int reg, unsigned int val)
 {
 	int ret;
 
-	mutex_lock(&map->lock);
+	map->lock(map);
 
 	ret = _regmap_write(map, reg, val);
 
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 
 	return ret;
 }
@@ -592,11 +620,11 @@ int regmap_raw_write(struct regmap *map, unsigned int reg,
 {
 	int ret;
 
-	mutex_lock(&map->lock);
+	map->lock(map);
 
 	ret = _regmap_raw_write(map, reg, val, val_len);
 
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 
 	return ret;
 }
@@ -626,7 +654,7 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
 	if (!map->format.parse_val)
 		return -EINVAL;
 
-	mutex_lock(&map->lock);
+	map->lock(map);
 
 	/* No formatting is require if val_byte is 1 */
 	if (val_bytes == 1) {
@@ -647,7 +675,7 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
 		kfree(wval);
 
 out:
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(regmap_bulk_write);
@@ -721,11 +749,11 @@ int regmap_read(struct regmap *map, unsigned int reg, unsigned int *val)
 {
 	int ret;
 
-	mutex_lock(&map->lock);
+	map->lock(map);
 
 	ret = _regmap_read(map, reg, val);
 
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 
 	return ret;
 }
@@ -750,7 +778,7 @@ int regmap_raw_read(struct regmap *map, unsigned int reg, void *val,
 	unsigned int v;
 	int ret, i;
 
-	mutex_lock(&map->lock);
+	map->lock(map);
 
 	if (regmap_volatile_range(map, reg, val_count) || map->cache_bypass ||
 	    map->cache_type == REGCACHE_NONE) {
@@ -771,7 +799,7 @@ int regmap_raw_read(struct regmap *map, unsigned int reg, void *val,
 	}
 
  out:
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 
 	return ret;
 }
@@ -824,7 +852,7 @@ static int _regmap_update_bits(struct regmap *map, unsigned int reg,
 	int ret;
 	unsigned int tmp, orig;
 
-	mutex_lock(&map->lock);
+	map->lock(map);
 
 	ret = _regmap_read(map, reg, &orig);
 	if (ret != 0)
@@ -841,7 +869,7 @@ static int _regmap_update_bits(struct regmap *map, unsigned int reg,
 	}
 
 out:
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 
 	return ret;
 }
@@ -881,7 +909,7 @@ int regmap_update_bits_lazy(struct regmap *map, unsigned int reg,
 	int ret, new;
 	unsigned int tmp;
 
-	mutex_lock(&map->lock);
+	map->lock(map);
 
 	ret = _regmap_read(map, reg, &tmp);
 	if (ret != 0)
@@ -894,7 +922,7 @@ int regmap_update_bits_lazy(struct regmap *map, unsigned int reg,
 	}
 
 out:
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 
 	return ret;
 }
@@ -943,7 +971,7 @@ int regmap_register_patch(struct regmap *map, const struct reg_default *regs,
 	if (map->patch)
 		return -EBUSY;
 
-	mutex_lock(&map->lock);
+	map->lock(map);
 
 	bypass = map->cache_bypass;
 
@@ -971,7 +999,7 @@ int regmap_register_patch(struct regmap *map, const struct reg_default *regs,
 out:
 	map->cache_bypass = bypass;
 
-	mutex_unlock(&map->lock);
+	map->unlock(map);
 
 	return ret;
 }