We have a use case in the at24 EEPROM driver (recently converted to using regmap instead of raw i2c/smbus calls) where we read from/write to the regmap in a loop, while protecting the entire loop with a mutex.
Currently this implicitly makes us use two mutexes - one in the driver and one in regmap. While browsing the code for similar use cases I noticed a significant number of places where locking *seems* redundant. Allow users to completely disable any locking mechanisms in regmap config. Signed-off-by: Bartosz Golaszewski <[email protected]> --- drivers/base/regmap/regmap.c | 9 ++++++++- include/linux/regmap.h | 5 +++++ 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c index 8d516a9bfc01..72917b2fc10e 100644 --- a/drivers/base/regmap/regmap.c +++ b/drivers/base/regmap/regmap.c @@ -459,6 +459,11 @@ static void regmap_unlock_hwlock_irqrestore(void *__map) } #endif +static void regmap_lock_unlock_empty(void *__map) +{ + +} + static void regmap_lock_mutex(void *__map) { struct regmap *map = __map; @@ -669,7 +674,9 @@ struct regmap *__regmap_init(struct device *dev, goto err; } - if (config->lock && config->unlock) { + if (config->disable_locking) { + map->lock = map->unlock = regmap_lock_unlock_empty; + } else if (config->lock && config->unlock) { map->lock = config->lock; map->unlock = config->unlock; map->lock_arg = config->lock_arg; diff --git a/include/linux/regmap.h b/include/linux/regmap.h index 15eddc1353ba..072a90229e34 100644 --- a/include/linux/regmap.h +++ b/include/linux/regmap.h @@ -264,6 +264,9 @@ typedef void (*regmap_unlock)(void *); * field is NULL but precious_table (see below) is not, the * check is performed on such table (a register is precious if * it belongs to one of the ranges specified by precious_table). + * @disable_locking: This regmap is either protected by external means or + * is guaranteed not be be accessed from multiple threads. + * Don't use any locking mechanisms. * @lock: Optional lock callback (overrides regmap's default lock * function, based on spinlock or mutex). * @unlock: As above for unlocking. @@ -333,6 +336,8 @@ struct regmap_config { bool (*readable_reg)(struct device *dev, unsigned int reg); bool (*volatile_reg)(struct device *dev, unsigned int reg); bool (*precious_reg)(struct device *dev, unsigned int reg); + + bool disable_locking; regmap_lock lock; regmap_unlock unlock; void *lock_arg; -- 2.15.1
