Merge tag 'regmap-offload-update-bits' into regmap-next

regmap: Allow buses to provide a custom update_bits() operation

Some buses provide a native _update_bits() operation which for uncached
registers is faster than doing a read/modify/write cycle as it is a
single bus transaction.  Add support for implementing this to regmap.

# gpg: Signature made Tue 06 Oct 2015 16:21:47 BST using RSA key ID 5D5487D0
# gpg: Oops: keyid_from_fingerprint: no pubkey
# gpg: Oops: keyid_from_fingerprint: no pubkey
# gpg: key 00000000 occurs more than once in the trustdb
# gpg: key 16005C11: no public key for trusted key - skipped
# gpg: key 16005C11 marked as ultimately trusted
# gpg: Good signature from "Mark Brown <broonie@sirena.org.uk>"
# gpg:                 aka "Mark Brown <broonie@debian.org>"
# gpg:                 aka "Mark Brown <broonie@kernel.org>"
# gpg:                 aka "Mark Brown <broonie@tardis.ed.ac.uk>"
# gpg:                 aka "Mark Brown <broonie@linaro.org>"
# gpg:                 aka "Mark Brown <Mark.Brown@linaro.org>"

2 files changed, 20 insertions, 11 deletions

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index cc557886ab23..628ad7ac078b 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -98,6 +98,8 @@ struct regmap {
 
         int (*reg_read)(void *context, unsigned int reg, unsigned int *val);
         int (*reg_write)(void *context, unsigned int reg, unsigned int val);
+        int (*reg_update_bits)(void *context, unsigned int reg,
+                               unsigned int mask, unsigned int val);
 
         bool defer_caching;
 
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index afaf56200674..8cd155af3d63 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -619,6 +619,7 @@ struct regmap *__regmap_init(struct device *dev,
                 goto skip_format_initialization;
         } else {
                 map->reg_read  = _regmap_bus_read;
+                map->reg_update_bits = bus->reg_update_bits;
         }
 
         reg_endian = regmap_get_reg_endian(bus, config);
@@ -2509,20 +2510,26 @@ static int _regmap_update_bits(struct regmap *map, unsigned int reg,
         int ret;
         unsigned int tmp, orig;
 
-        ret = _regmap_read(map, reg, &orig);
-        if (ret != 0)
-                return ret;
+        if (change)
+                *change = false;
 
-        tmp = orig & ~mask;
-        tmp |= val & mask;
-
-        if (force_write || (tmp != orig)) {
-                ret = _regmap_write(map, reg, tmp);
-                if (change)
+        if (regmap_volatile(map, reg) && map->reg_update_bits) {
+                ret = map->reg_update_bits(map->bus_context, reg, mask, val);
+                if (ret == 0 && change)
                         *change = true;
         } else {
-                if (change)
-                        *change = false;
+                ret = _regmap_read(map, reg, &orig);
+                if (ret != 0)
+                        return ret;
+
+                tmp = orig & ~mask;
+                tmp |= val & mask;
+
+                if (force_write || (tmp != orig)) {
+                        ret = _regmap_write(map, reg, tmp);
+                        if (ret == 0 && change)
+                                *change = true;
+                }
         }
 
         return ret;