firmware: arm_scmi: Ensure that the message-id supports fastchannel

commit 94a263f981a3fa3d93f65c31e0fed0756736be43 upstream.

Currently the perf and powercap protocol relies on the protocol domain
attributes, which just ensures that one fastchannel per domain, before
instantiating fastchannels for all possible message-ids. Fix this by
ensuring that each message-id supports fastchannel before initialization.

Logs:
  |  scmi: Failed to get FC for protocol 13 [MSG_ID:6 / RES_ID:0] - ret:-95. Using regular messaging
  |  scmi: Failed to get FC for protocol 13 [MSG_ID:6 / RES_ID:1] - ret:-95. Using regular messaging
  |  scmi: Failed to get FC for protocol 13 [MSG_ID:6 / RES_ID:2] - ret:-95. Using regular messaging

CC: stable@vger.kernel.org
Reported-by: Johan Hovold <johan+linaro@kernel.org>
Closes: https://lore.kernel.org/lkml/ZoQjAWse2YxwyRJv@hovoldconsulting.com/
Fixes: 6f9ea4dabd2d ("firmware: arm_scmi: Generalize the fast channel support")
Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Tested-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
[Cristian: Modified the condition checked to establish support or not]
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Message-Id: <20250429141108.406045-2-cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 45 insertions, 33 deletions

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 24babf87adb9..d1fd2e492909 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -1548,6 +1548,39 @@ out:
 }
 
 /**
+ * scmi_protocol_msg_check  - Check protocol message attributes
+ *
+ * @ph: A reference to the protocol handle.
+ * @message_id: The ID of the message to check.
+ * @attributes: A parameter to optionally return the retrieved message
+ *		attributes, in case of Success.
+ *
+ * An helper to check protocol message attributes for a specific protocol
+ * and message pair.
+ *
+ * Return: 0 on SUCCESS
+ */
+static int scmi_protocol_msg_check(const struct scmi_protocol_handle *ph,
+				   u32 message_id, u32 *attributes)
+{
+	int ret;
+	struct scmi_xfer *t;
+
+	ret = xfer_get_init(ph, PROTOCOL_MESSAGE_ATTRIBUTES,
+			    sizeof(__le32), 0, &t);
+	if (ret)
+		return ret;
+
+	put_unaligned_le32(message_id, t->tx.buf);
+	ret = do_xfer(ph, t);
+	if (!ret && attributes)
+		*attributes = get_unaligned_le32(t->rx.buf);
+	xfer_put(ph, t);
+
+	return ret;
+}
+
+/**
  * struct scmi_iterator  - Iterator descriptor
  * @msg: A reference to the message TX buffer; filled by @prepare_message with
  *	 a proper custom command payload for each multi-part command request.
@@ -1688,6 +1721,7 @@ scmi_common_fastchannel_init(const struct scmi_protocol_handle *ph,
 	int ret;
 	u32 flags;
 	u64 phys_addr;
+	u32 attributes;
 	u8 size;
 	void __iomem *addr;
 	struct scmi_xfer *t;
@@ -1696,6 +1730,15 @@ scmi_common_fastchannel_init(const struct scmi_protocol_handle *ph,
 	struct scmi_msg_resp_desc_fc *resp;
 	const struct scmi_protocol_instance *pi = ph_to_pi(ph);
 
+	/* Check if the MSG_ID supports fastchannel */
+	ret = scmi_protocol_msg_check(ph, message_id, &attributes);
+	if (ret || !MSG_SUPPORTS_FASTCHANNEL(attributes)) {
+		dev_dbg(ph->dev,
+			"Skip FC init for 0x%02X/%d  domain:%d - ret:%d\n",
+			pi->proto->id, message_id, domain, ret);
+		return;
+	}
+
 	if (!p_addr) {
 		ret = -EINVAL;
 		goto err_out;
@@ -1820,39 +1863,6 @@ static void scmi_common_fastchannel_db_ring(struct scmi_fc_db_info *db)
 #endif
 }
 
-/**
- * scmi_protocol_msg_check  - Check protocol message attributes
- *
- * @ph: A reference to the protocol handle.
- * @message_id: The ID of the message to check.
- * @attributes: A parameter to optionally return the retrieved message
- *		attributes, in case of Success.
- *
- * An helper to check protocol message attributes for a specific protocol
- * and message pair.
- *
- * Return: 0 on SUCCESS
- */
-static int scmi_protocol_msg_check(const struct scmi_protocol_handle *ph,
-				   u32 message_id, u32 *attributes)
-{
-	int ret;
-	struct scmi_xfer *t;
-
-	ret = xfer_get_init(ph, PROTOCOL_MESSAGE_ATTRIBUTES,
-			    sizeof(__le32), 0, &t);
-	if (ret)
-		return ret;
-
-	put_unaligned_le32(message_id, t->tx.buf);
-	ret = do_xfer(ph, t);
-	if (!ret && attributes)
-		*attributes = get_unaligned_le32(t->rx.buf);
-	xfer_put(ph, t);
-
-	return ret;
-}
-
 static const struct scmi_proto_helpers_ops helpers_ops = {
 	.extended_name_get = scmi_common_extended_name_get,
 	.iter_response_init = scmi_iterator_init,
diff --git a/drivers/firmware/arm_scmi/protocols.h b/drivers/firmware/arm_scmi/protocols.h
index 9fc2f1e293d4..095b14a2d0a3 100644
--- a/drivers/firmware/arm_scmi/protocols.h
+++ b/drivers/firmware/arm_scmi/protocols.h
@@ -29,6 +29,8 @@
 #define PROTOCOL_REV_MAJOR(x)	((u16)(FIELD_GET(PROTOCOL_REV_MAJOR_MASK, (x))))
 #define PROTOCOL_REV_MINOR(x)	((u16)(FIELD_GET(PROTOCOL_REV_MINOR_MASK, (x))))
 
+#define MSG_SUPPORTS_FASTCHANNEL(x)	((x) & BIT(0))
+
 enum scmi_common_cmd {
 	PROTOCOL_VERSION = 0x0,
 	PROTOCOL_ATTRIBUTES = 0x1,