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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: Mark Brown <broonie@kernel.org>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20210825205041.927788-2-vladimir.oltean@nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Vladimir Oltean 2021-08-25 23:50:40 +03:00 committed by Mark Brown
parent 6efb943b86
commit 67021f25d9
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
3 changed files with 36 additions and 5 deletions
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4
drivers/base/regmap/internal.h
View File

@ -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;

35
drivers/base/regmap/regmap.c
View File

@ -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) {
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);
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;

2
include/linux/regmap.h
View File

@ -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;