Merge tag 'hwlock-v6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux

Pull hwspinlock updates from Bjorn Andersson:
 "This introduces a mechanism in the hardware spinlock framework, and
  the Qualcomm TCSR mutex driver, for allowing clients to bust locks
  held by a remote processor in the event that this enters a faulty
  state while holding the shared lock"

* tag 'hwlock-v6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux:
  hwspinlock: qcom: implement bust operation
  hwspinlock: Introduce hwspin_lock_bust()

3 files changed, 56 insertions, 0 deletions

diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c
index 0c0a932c00f3..6505261e6068 100644
--- a/drivers/hwspinlock/hwspinlock_core.c
+++ b/drivers/hwspinlock/hwspinlock_core.c
@@ -306,6 +306,34 @@ void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
 EXPORT_SYMBOL_GPL(__hwspin_unlock);
 
 /**
+ * hwspin_lock_bust() - bust a specific hwspinlock
+ * @hwlock: a previously-acquired hwspinlock which we want to bust
+ * @id: identifier of the remote lock holder, if applicable
+ *
+ * This function will bust a hwspinlock that was previously acquired as
+ * long as the current owner of the lock matches the id given by the caller.
+ *
+ * Context: Process context.
+ *
+ * Returns: 0 on success, or -EINVAL if the hwspinlock does not exist, or
+ * the bust operation fails, and -EOPNOTSUPP if the bust operation is not
+ * defined for the hwspinlock.
+ */
+int hwspin_lock_bust(struct hwspinlock *hwlock, unsigned int id)
+{
+	if (WARN_ON(!hwlock))
+		return -EINVAL;
+
+	if (!hwlock->bank->ops->bust) {
+		pr_err("bust operation not defined\n");
+		return -EOPNOTSUPP;
+	}
+
+	return hwlock->bank->ops->bust(hwlock, id);
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_bust);
+
+/**
  * of_hwspin_lock_simple_xlate - translate hwlock_spec to return a lock id
  * @hwlock_spec: hwlock specifier as found in the device tree
  *
diff --git a/drivers/hwspinlock/hwspinlock_internal.h b/drivers/hwspinlock/hwspinlock_internal.h
index 29892767bb7a..f298fc0ee5ad 100644
--- a/drivers/hwspinlock/hwspinlock_internal.h
+++ b/drivers/hwspinlock/hwspinlock_internal.h
@@ -21,6 +21,8 @@ struct hwspinlock_device;
  * @trylock: make a single attempt to take the lock. returns 0 on
  *	     failure and true on success. may _not_ sleep.
  * @unlock:  release the lock. always succeed. may _not_ sleep.
+ * @bust:    optional, platform-specific bust handler, called by hwspinlock
+ *	     core to bust a specific lock.
  * @relax:   optional, platform-specific relax handler, called by hwspinlock
  *	     core while spinning on a lock, between two successive
  *	     invocations of @trylock. may _not_ sleep.
@@ -28,6 +30,7 @@ struct hwspinlock_device;
 struct hwspinlock_ops {
 	int (*trylock)(struct hwspinlock *lock);
 	void (*unlock)(struct hwspinlock *lock);
+	int (*bust)(struct hwspinlock *lock, unsigned int id);
 	void (*relax)(struct hwspinlock *lock);
 };
 
diff --git a/drivers/hwspinlock/qcom_hwspinlock.c b/drivers/hwspinlock/qcom_hwspinlock.c
index 814dfe8697bf..0390979fd765 100644
--- a/drivers/hwspinlock/qcom_hwspinlock.c
+++ b/drivers/hwspinlock/qcom_hwspinlock.c
@@ -64,9 +64,34 @@ static void qcom_hwspinlock_unlock(struct hwspinlock *lock)
 		pr_err("%s: failed to unlock spinlock\n", __func__);
 }
 
+static int qcom_hwspinlock_bust(struct hwspinlock *lock, unsigned int id)
+{
+	struct regmap_field *field = lock->priv;
+	u32 owner;
+	int ret;
+
+	ret = regmap_field_read(field, &owner);
+	if (ret) {
+		dev_err(lock->bank->dev, "unable to query spinlock owner\n");
+		return ret;
+	}
+
+	if (owner != id)
+		return 0;
+
+	ret = regmap_field_write(field, 0);
+	if (ret) {
+		dev_err(lock->bank->dev, "failed to bust spinlock\n");
+		return ret;
+	}
+
+	return 0;
+}
+
 static const struct hwspinlock_ops qcom_hwspinlock_ops = {
 	.trylock	= qcom_hwspinlock_trylock,
 	.unlock		= qcom_hwspinlock_unlock,
+	.bust		= qcom_hwspinlock_bust,
 };
 
 static const struct regmap_config sfpb_mutex_config = {