[PATCH v2 3/4] soc: qcom: smem: Add qcom_smem_bust_hwspin_lock_by_host()

[Chris Lew]

Add qcom_smem_bust_hwspin_lock_by_host to enable remoteproc to bust the
hwspin_lock owned by smem. In the event the remoteproc crashes
unexpectedly, the remoteproc driver can invoke this API to try and bust
the hwspin_lock and release the lock if still held by the remoteproc
device.

Signed-off-by: Chris Lew <quic_clew@xxxxxxxxxxx>
---
 drivers/soc/qcom/smem.c       | 28 ++++++++++++++++++++++++++++
 include/linux/soc/qcom/smem.h |  2 ++
 2 files changed, 30 insertions(+)

diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c
index 7191fa0c087f..683599990387 100644
--- a/drivers/soc/qcom/smem.c
+++ b/drivers/soc/qcom/smem.c
@@ -359,6 +359,34 @@ static struct qcom_smem *__smem;
 /* Timeout (ms) for the trylock of remote spinlocks */
 #define HWSPINLOCK_TIMEOUT	1000
 
+/* The qcom hwspinlock id is always plus one from the smem host id */
+#define SMEM_HOST_ID_TO_HWSPINLOCK_ID(__x) ((__x) + 1)
+
+/**
+ * qcom_smem_bust_hwspin_lock_by_host() - bust the smem hwspinlock for an smem host id
+ * @host:	remote processor id
+ *
+ * Busts the hwspin_lock for the given smem host id. This helper is intended for remoteproc drivers
+ * that manage remoteprocs with an equivalent smem driver instance in the remote firmware. Drivers
+ * can force a release of the smem hwspin_lock if the rproc unexpectedly goes into a bad state.
+ *
+ * Context: Process context.
+ *
+ * Returns: 0 on success, otherwise negative errno.
+ */
+int qcom_smem_bust_hwspin_lock_by_host(unsigned host)
+{
+	if (!__smem)
+		return -EPROBE_DEFER;
+
+	/* This function is for remote procs, so ignore SMEM_HOST_APPS */
+	if (host == SMEM_HOST_APPS ||host >= SMEM_HOST_COUNT)
+		return -EINVAL;
+
+	return hwspin_lock_bust(__smem->hwlock, SMEM_HOST_ID_TO_HWSPINLOCK_ID(host));
+}
+EXPORT_SYMBOL_GPL(qcom_smem_bust_hwspin_lock_by_host);
+
 /**
  * qcom_smem_is_available() - Check if SMEM is available
  *
diff --git a/include/linux/soc/qcom/smem.h b/include/linux/soc/qcom/smem.h
index a36a3b9d4929..959eea0812bb 100644
--- a/include/linux/soc/qcom/smem.h
+++ b/include/linux/soc/qcom/smem.h
@@ -14,4 +14,6 @@ phys_addr_t qcom_smem_virt_to_phys(void *p);
 
 int qcom_smem_get_soc_id(u32 *id);
 
+int qcom_smem_bust_hwspin_lock_by_host(unsigned host);
+
 #endif

-- 
2.25.1