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>

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index b95fd1f25295d93f1b04f9d37ce309996e242fee..e46c279f828062bd3b243c475e86ec7fdfd13985 100644 (file)
--- 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 5157fa04c2f0e04e6120878a97764d4375d52769..cca46007d969baf21aff58921318fe1124f708fa 100644 (file)
--- 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 87f54dbf601b90adf01e602ec200e5f967472d66..4ad18505e9aecf6f6426b718e5bb910e10b82410 100644 (file)
--- 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;
 }
@@ -361,11 +361,11 @@ out:
  */
 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);
 
@@ -380,9 +380,9 @@ 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);
 
@@ -399,11 +399,11 @@ 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 bde30c5d5ee9df9c321e25283fddb830a185551c..6b4a775b439b1635895883cef5c291908250d2c0 100644 (file)
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -158,6 +158,26 @@ 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
  *
@@ -187,7 +207,15 @@ 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;
@@ -365,7 +393,7 @@ 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);
@@ -384,7 +412,7 @@ 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;
 }
@@ -536,11 +564,11 @@ 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;
 }
@@ -567,11 +595,11 @@ 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;
 }
@@ -601,7 +629,7 @@ 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) {
@@ -622,7 +650,7 @@ 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);
@@ -696,11 +724,11 @@ 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;
 }
@@ -725,7 +753,7 @@ 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) {
@@ -746,7 +774,7 @@ int regmap_raw_read(struct regmap *map, unsigned int reg, void *val,
        }
 
  out:
-       mutex_unlock(&map->lock);
+       map->unlock(map);
 
        return ret;
 }
@@ -799,7 +827,7 @@ 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)
@@ -816,7 +844,7 @@ static int _regmap_update_bits(struct regmap *map, unsigned int reg,
        }
 
 out:
-       mutex_unlock(&map->lock);
+       map->unlock(map);
 
        return ret;
 }
@@ -883,7 +911,7 @@ 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;
 
@@ -911,7 +939,7 @@ 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 8fd341e613d644d1fb88626f4269e68e0882c79f..f14588a96eafc8656931652b4e91991ac950eef3 100644 (file)
--- 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;