From 9f655d719048c0eda67e041f365325f07ac0eef5 Mon Sep 17 00:00:00 2001 From: Colin Patrick McCabe Date: Thu, 20 Oct 2011 14:44:17 -0700 Subject: regmap: add regmap_update_bits_lazy Add regmap_update_bits_lazy. Like regmap_update_bits, this performs a read-modify-write cycle on a regmap register, but it skips the write if nothing has changed. Change-Id: Id075f711770a6bf15dea9ae085593fef268491ac Signed-off-by: Colin Patrick McCabe Reviewed-on: http://git-master/r/59460 Reviewed-by: Dan Willemsen Rebase-Id: R93e1c3cf4a506cb17346f4e981a60350846a856e --- drivers/base/regmap/regmap.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) (limited to 'drivers/base/regmap') diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c index 20663f8dae45..843f722ff9cd 100644 --- a/drivers/base/regmap/regmap.c +++ b/drivers/base/regmap/regmap.c @@ -450,3 +450,39 @@ out: return ret; } EXPORT_SYMBOL_GPL(regmap_update_bits); + +/** + * remap_update_bits_lazy: Perform a read/modify/write cycle on the register + * map. Only write new contents if they differ from the previous ones. + * + * @map: Register map to update + * @reg: Register to update + * @mask: Bitmask to change + * @val: New value for bitmask + * + * Returns zero for success, a negative number on error. + */ +int regmap_update_bits_lazy(struct regmap *map, unsigned int reg, + unsigned int mask, unsigned int val) +{ + int ret, new; + unsigned int tmp; + + mutex_lock(&map->lock); + + ret = _regmap_read(map, reg, &tmp); + if (ret != 0) + goto out; + + new = tmp & ~mask; + new |= val & mask; + if (new != tmp) { + ret = _regmap_write(map, reg, new); + } + +out: + mutex_unlock(&map->lock); + + return ret; +} +EXPORT_SYMBOL_GPL(regmap_update_bits_lazy); -- cgit v1.2.3