[PATCH 1/7] hwspinlock: Introduce refcount

Chris Lew
2024-05-16T22:59:45Z

From: Richard Maina <quic_rmaina@quicinc.com>

Currently each device receives a dedicated hwspinlock that is not
accesible to other device drivers. In order to allow multiple consumers
access to the same hwspinlock, introduce a refcount to hwspinlock struct
and implement refcounting infrastructure.

Signed-off-by: Richard Maina <quic_rmaina@quicinc.com>
Signed-off-by: Chris Lew <quic_clew@quicinc.com>
---
drivers/hwspinlock/hwspinlock_core.c | 14 +++++++++-----
drivers/hwspinlock/hwspinlock_internal.h | 2 ++
2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c
index 0c0a932c00f3..29b33072ff57 100644
--- a/drivers/hwspinlock/hwspinlock_core.c
+++ b/drivers/hwspinlock/hwspinlock_core.c
@@ -428,6 +428,7 @@ static int hwspin_lock_register_single(struct hwspinlock *hwlock, int id)
int ret;

mutex_lock(&hwspinlock_tree_lock);
+ hwlock->refcnt = 0;

ret = radix_tree_insert(&hwspinlock_tree, id, hwlock);
if (ret) {
@@ -671,6 +672,8 @@ static int __hwspin_lock_request(struct hwspinlock *hwlock)

ret = 0;

+ hwlock->refcnt++;
+
/* mark hwspinlock as used, should not fail */
tmp = radix_tree_tag_clear(&hwspinlock_tree, hwlock_to_id(hwlock),
HWSPINLOCK_UNUSED);
@@ -829,12 +832,13 @@ int hwspin_lock_free(struct hwspinlock *hwlock)
/* notify the underlying device that power is not needed */
pm_runtime_put(dev);

- /* mark this hwspinlock as available */
- tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock_to_id(hwlock),
- HWSPINLOCK_UNUSED);
+ if (--hwlock->refcnt == 0) {
+ /* mark this hwspinlock as available */
+ tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock_to_id(hwlock), HWSPINLOCK_UNUSED);

- /* sanity check (this shouldn't happen) */
- WARN_ON(tmp != hwlock);
+ /* sanity check (this shouldn't happen) */
+ WARN_ON(tmp != hwlock);
+ }

module_put(dev->driver->owner);

diff --git a/drivers/hwspinlock/hwspinlock_internal.h b/drivers/hwspinlock/hwspinlock_internal.h
index 29892767bb7a..12f230b40693 100644
--- a/drivers/hwspinlock/hwspinlock_internal.h
+++ b/drivers/hwspinlock/hwspinlock_internal.h
@@ -35,11 +35,13 @@ struct hwspinlock_ops {
* struct hwspinlock - this struct represents a single hwspinlock instance
* @bank: the hwspinlock_device structure which owns this lock
* @lock: initialized and used by hwspinlock core
+ * @refcnt: counter for the number of existing references to the hwspinlock
* @priv: private data, owned by the underlying platform-specific hwspinlock drv
*/
struct hwspinlock {
struct hwspinlock_device *bank;
spinlock_t lock;
+ unsigned int refcnt;
void *priv;
};

--
2.25.1