[PATCH v5 1/8] regmap: Support atomic forced uncached reads
From: Sander Vanheule <sander@svanheule.net>
Date: 2021-06-12 21:13:41
Also in:
linux-gpio, linux-leds, lkml
Subsystem:
driver core, kobjects, debugfs and sysfs, register map abstraction, the rest · Maintainers:
Greg Kroah-Hartman, "Rafael J. Wysocki", Danilo Krummrich, Mark Brown, Linus Torvalds
When a user wants to read a single uncached register, cache bypassing can be enabled. However, this is not atomic unless an external lock is used for the regmap. When using regcache_cache_bypass, the original bypass state also cannot be restored. Add support to atomically read a single uncached value, bypassing any regmap cache. Signed-off-by: Sander Vanheule <sander@svanheule.net> --- drivers/base/regmap/regmap.c | 33 +++++++++++++++++++++++++++++++++ include/linux/regmap.h | 8 ++++++++ 2 files changed, 41 insertions(+)
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index fe3e38dd5324..a828f05535b7 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c@@ -2745,6 +2745,39 @@ int regmap_read(struct regmap *map, unsigned int reg, unsigned int *val) } EXPORT_SYMBOL_GPL(regmap_read); +/** + * regmap_read_bypassed() - Read a value from a single register, bypassing the cache + * + * @map: Register map to read from + * @reg: Register to be read from + * @val: Pointer to store read value + * + * A value of zero will be returned on success, a negative errno will + * be returned in error cases. + */ +int regmap_read_bypassed(struct regmap *map, unsigned int reg, unsigned int *val) +{ + bool bypass; + int ret; + + if (!IS_ALIGNED(reg, map->reg_stride)) + return -EINVAL; + + map->lock(map->lock_arg); + + bypass = map->cache_bypass; + map->cache_bypass = true; + + ret = _regmap_read(map, reg, val); + + map->cache_bypass = bypass; + + map->unlock(map->lock_arg); + + return ret; +} +EXPORT_SYMBOL_GPL(regmap_read_bypassed); + /** * regmap_raw_read() - Read raw data from the device *
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index f5f08dd0a116..a54dc00326ba 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h@@ -1133,6 +1133,7 @@ int regmap_multi_reg_write_bypassed(struct regmap *map, int regmap_raw_write_async(struct regmap *map, unsigned int reg, const void *val, size_t val_len); int regmap_read(struct regmap *map, unsigned int reg, unsigned int *val); +int regmap_read_bypassed(struct regmap *map, unsigned int reg, unsigned int *val); int regmap_raw_read(struct regmap *map, unsigned int reg, void *val, size_t val_len); int regmap_noinc_read(struct regmap *map, unsigned int reg,
@@ -1607,6 +1608,13 @@ static inline int regmap_read(struct regmap *map, unsigned int reg, return -EINVAL; } +static inline int regmap_read_bypassed(struct regmap *map, unsigned int reg, + unsigned int *val) +{ + WARN_ONCE(1, "regmap API is disabled"); + return -EINVAL; +} + static inline int regmap_raw_read(struct regmap *map, unsigned int reg, void *val, size_t val_len) {
--
2.31.1