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, 2 insertions, 2 deletions

diff --git a/drivers/base/regmap/regcache-rbtree.c b/drivers/base/regmap/regcache-rbtree.c
index 5157fa04c2f0..cca46007d969 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;
 }