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>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index b95fd1f25295..e46c279f8280 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 */