hwspinlock: qcom: implement bust operation

Implement a new operation qcom_hwspinlock_bust() which can be invoked
to bust any locks that are in use when a remoteproc is stopped or
crashed.
Signed-off-by: Richard Maina <quic_rmaina@quicinc.com>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Chris Lew <quic_clew@quicinc.com>
Link: https://lore.kernel.org/r/20240529-hwspinlock-bust-v3-2-c8b924ffa5a2@quicinc.comSigned-off-by: Bjorn Andersson <andersson@kernel.org>

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 = {