From a42678c4c8b5f6d489829ffc3071fa1f08ee99d1 Mon Sep 17 00:00:00 2001
From: Stephen Warren <swarren@nvidia.com>
Date: Wed, 4 Apr 2012 15:48:28 -0600
Subject: [PATCH] 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>
---
drivers/base/regmap/internal.h | 8 +++-
drivers/base/regmap/regcache-rbtree.c | 4 +-
drivers/base/regmap/regcache.c | 20 ++++-----
drivers/base/regmap/regmap.c | 62 +++++++++++++++++++--------
include/linux/regmap.h | 3 ++
5 files changed, 67 insertions(+), 30 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 92b779ee002b..e49e71fab184 100644
--- a/drivers/base/regmap/regcache-rbtree.c
+++ b/drivers/base/regmap/regcache-rbtree.c
@@ -140,7 +140,7 @@ 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)) {
@@ -161,7 +161,7 @@ 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 74b69095def6..d4368e8b6f9d 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -264,7 +264,7 @@ 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",
@@ -296,7 +296,7 @@ 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;
}
@@ -323,7 +323,7 @@ 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;
@@ -342,7 +342,7 @@ 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;
}
@@ -362,11 +362,11 @@ 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);
@@ -381,9 +381,9 @@ 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);
@@ -400,11 +400,11 @@ 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 8cfe79c6323f..004a08d54f07 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);
@@ -410,7 +438,7 @@ 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;
}
@@ -562,11 +590,11 @@ 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;
}
@@ -593,11 +621,11 @@ 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;
}
@@ -627,7 +655,7 @@ 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) {
@@ -648,7 +676,7 @@ 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);
@@ -722,11 +750,11 @@ 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;
}
@@ -751,7 +779,7 @@ 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) {
@@ -772,7 +800,7 @@ int regmap_raw_read(struct regmap *map, unsigned int reg, void *val,
}
out:
- mutex_unlock(&map->lock);
+ map->unlock(map);
return ret;
}
@@ -825,7 +853,7 @@ 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)
@@ -842,7 +870,7 @@ static int _regmap_update_bits(struct regmap *map, unsigned int reg,
}
out:
- mutex_unlock(&map->lock);
+ map->unlock(map);
return ret;
}
@@ -909,7 +937,7 @@ 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;
@@ -937,7 +965,7 @@ 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;
}
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 8fd341e613d6..f14588a96eaf 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -110,6 +110,8 @@ typedef void (*regmap_hw_free_context)(void *context);
/**
* Description of a hardware bus for the register map infrastructure.
*
+ * @fast_io: Register IO is fast. Use a spinlock instead of a mutex
+ * to perform locking.
* @write: Write operation.
* @gather_write: Write operation with split register/value, return -ENOTSUPP
* if not implemented on a given device.
@@ -119,6 +121,7 @@ typedef void (*regmap_hw_free_context)(void *context);
* a read.
*/
struct regmap_bus {
+ bool fast_io;
regmap_hw_write write;
regmap_hw_gather_write gather_write;
regmap_hw_read read;
--
2.34.1