drivers: firmware: scmi: add api to clear channel status

Add scmi_shmem_clear_channel_status() function that always sets
channel to FREE state after message processing.
It provides a standardized way for higher layer components
(such as mailbox drivers) to explicitly clear the SCMI shared
memory channel status, ensuring proper channel state management
and avoiding potential race conditions in multi-layer SCMI
implementations.

Signed-off-by: Yongxu Wang <[email protected]>

Author: yongxu-wang15

drivers/firmware/scmi/shmem.c

@@ -39,6 +39,17 @@ int scmi_shmem_get_channel_status(const struct device *dev, uint32_t *status)
 	return 0;
 }
 
+void scmi_shmem_clear_channel_status(const struct device *dev)
+{
+	struct scmi_shmem_data *data;
+	struct scmi_shmem_layout *layout;
+
+	data = dev->data;
+	layout = (struct scmi_shmem_layout *)data->regmap;
+
+	layout->chan_status |= SCMI_SHMEM_CHAN_STATUS_FREE_BIT;
+}
+
 static void scmi_shmem_memcpy(mm_reg_t dst, mm_reg_t src, uint32_t bytes)
 {
 	int i;

include/zephyr/drivers/firmware/scmi/shmem.h

@@ -93,4 +93,11 @@ int scmi_shmem_vendor_write_message(struct scmi_shmem_layout *layout);
  */
 int scmi_shmem_vendor_read_message(const struct scmi_shmem_layout *layout);
 
+/**
+ * @brief Clear a SHMEM area channel status
+ *
+ * @param dev pointer to shmem device
+ */
+void scmi_shmem_clear_channel_status(const struct device *dev);
+
 #endif /* _INCLUDE_ZEPHYR_DRIVERS_FIRMWARE_SCMI_SHMEM_H_ */