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Date: Wed, 4 Apr 2012 15:48:28 -0600
From: Stephen Warren <swarren@...dotorg.org>
To: Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc: linux-kernel@...r.kernel.org, Stephen Warren <swarren@...dia.com>
Subject: [PATCH 1/6] regmap: introduce fast_io busses, and use a spinlock for them
From: Stephen Warren <swarren@...dia.com>
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.
Signed-off-by: Stephen Warren <swarren@...dia.com>
---
Mark, FYI, this whole series will be a dependency for the Tegra ASoC
series I'll post shortly.
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 606b83d..6ee4dc5 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 fb14a63..9eea758 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 nodes = 0;
int registers = 0;
- mutex_lock(&map->lock);
+ map->lock(map);
for (node = rb_first(&rbtree_ctx->root); node != NULL;
node = rb_next(node)) {
@@ -155,7 +155,7 @@ static int rbtree_show(struct seq_file *s, void *ignored)
seq_printf(s, "%d nodes, %d registers, average %d registers\n",
nodes, registers, registers / nodes);
- mutex_unlock(&map->lock);
+ map->unlock(map);
return 0;
}
diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 74b6909..d4368e8 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 178989a..831ec42 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
*
@@ -206,7 +226,15 @@ 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;
@@ -386,7 +414,7 @@ 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);
@@ -405,7 +433,7 @@ 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;
}
@@ -555,11 +583,11 @@ 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;
}
@@ -586,11 +614,11 @@ 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;
}
@@ -620,7 +648,7 @@ 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) {
@@ -641,7 +669,7 @@ 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);
@@ -715,11 +743,11 @@ 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;
}
@@ -744,7 +772,7 @@ 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) {
@@ -765,7 +793,7 @@ int regmap_raw_read(struct regmap *map, unsigned int reg, void *val,
}
out:
- mutex_unlock(&map->lock);
+ map->unlock(map);
return ret;
}
@@ -818,7 +846,7 @@ 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)
@@ -835,7 +863,7 @@ static int _regmap_update_bits(struct regmap *map, unsigned int reg,
}
out:
- mutex_unlock(&map->lock);
+ map->unlock(map);
return ret;
}
@@ -902,7 +930,7 @@ 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;
@@ -930,7 +958,7 @@ 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 a90abb6..48e9b86 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -109,6 +109,8 @@ typedef int (*regmap_hw_read)(struct device *dev,
/**
* 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.
@@ -118,6 +120,7 @@ typedef int (*regmap_hw_read)(struct device *dev,
* a read.
*/
struct regmap_bus {
+ bool fast_io;
regmap_hw_write write;
regmap_hw_gather_write gather_write;
regmap_hw_read read;
--
1.7.0.4
--
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