Unverified Commit 67021f25 authored by Vladimir Oltean's avatar Vladimir Oltean Committed by Mark Brown
Browse files

regmap: teach regmap to use raw spinlocks if requested in the config 



Some drivers might access regmap in a context where a raw spinlock is
held. An example is drivers/irqchip/irq-ls-extirq.c, which calls
regmap_update_bits() from struct irq_chip :: irq_set_type, which is a
method called by __irq_set_trigger() under the desc->lock raw spin lock.

Since desc->lock is a raw spin lock and the regmap internal lock for
mmio is a plain spinlock (which can become sleepable on RT), this is an
invalid locking scheme and we get a splat stating that this is a
"[ BUG: Invalid wait context ]".

It seems reasonable for regmap to have an option use a raw spinlock too,
so add that in the config such that drivers can request it.

Suggested-by: default avatarMark Brown <broonie@kernel.org>
Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20210825205041.927788-2-vladimir.oltean@nxp.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 6efb943b

drivers/base/regmap/internal.h

+4 −0
Original line number Diff line number Diff line
@@ -53,6 +53,10 @@ struct regmap { 
			spinlock_t spinlock;

			unsigned long spinlock_flags;

		};

		struct {

			raw_spinlock_t raw_spinlock;

			unsigned long raw_spinlock_flags;

		};

	};

	regmap_lock lock;

	regmap_unlock unlock;

drivers/base/regmap/regmap.c

+30 −5
Original line number Diff line number Diff line
@@ -523,6 +523,23 @@ __releases(&map->spinlock) 
	spin_unlock_irqrestore(&map->spinlock, map->spinlock_flags);

}



static void regmap_lock_raw_spinlock(void *__map)

__acquires(&map->raw_spinlock)

{

	struct regmap *map = __map;

	unsigned long flags;



	raw_spin_lock_irqsave(&map->raw_spinlock, flags);

	map->raw_spinlock_flags = flags;

}



static void regmap_unlock_raw_spinlock(void *__map)

__releases(&map->raw_spinlock)

{

	struct regmap *map = __map;

	raw_spin_unlock_irqrestore(&map->raw_spinlock, map->raw_spinlock_flags);

}



static void dev_get_regmap_release(struct device *dev, void *res)

{

	/*
@@ -760,11 +777,19 @@ struct regmap *__regmap_init(struct device *dev, 
	} else {

		if ((bus && bus->fast_io) ||

		    config->fast_io) {

			if (config->use_raw_spinlock) {

				raw_spin_lock_init(&map->raw_spinlock);

				map->lock = regmap_lock_raw_spinlock;

				map->unlock = regmap_unlock_raw_spinlock;

				lockdep_set_class_and_name(&map->raw_spinlock,

							   lock_key, lock_name);

			} else {

				spin_lock_init(&map->spinlock);

				map->lock = regmap_lock_spinlock;

				map->unlock = regmap_unlock_spinlock;

				lockdep_set_class_and_name(&map->spinlock,

							   lock_key, lock_name);

			}

		} else {

			mutex_init(&map->mutex);

			map->lock = regmap_lock_mutex;

include/linux/regmap.h

+2 −0
Original line number Diff line number Diff line
@@ -343,6 +343,7 @@ typedef void (*regmap_unlock)(void *); 
 * @ranges: Array of configuration entries for virtual address ranges.

 * @num_ranges: Number of range configuration entries.

 * @use_hwlock: Indicate if a hardware spinlock should be used.

 * @use_raw_spinlock: Indicate if a raw spinlock should be used.

 * @hwlock_id: Specify the hardware spinlock id.

 * @hwlock_mode: The hardware spinlock mode, should be HWLOCK_IRQSTATE,

 *		 HWLOCK_IRQ or 0.
@@ -402,6 +403,7 @@ struct regmap_config { 
	unsigned int num_ranges;



	bool use_hwlock;

	bool use_raw_spinlock;

	unsigned int hwlock_id;

	unsigned int hwlock_mode;