firmware: arm_scmi: Introduce a common SCMI v3.1 .extended_name_get helper

Introduce a new set of common protocol operations bound to the protocol
handle structure so that can be invoked by the protocol implementation code
even when protocols are built as distinct loadable kernel module without
the need of exporting new symbols, like already done with scmi_xfer_ops.

Add at first, as new common protocol helper, an .extended_name_get helper
which will ease implementation and will avoid code duplication when adding
new SCMIv3.1 per-protocol _NAME_GET commands.

Link: https://lore.kernel.org/r/20220330150551.2573938-11-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/firmware/arm_scmi/protocols.h b/drivers/firmware/arm_scmi/protocols.h
index b2a92d2b2986..5461fa333152 100644
--- a/drivers/firmware/arm_scmi/protocols.h
+++ b/drivers/firmware/arm_scmi/protocols.h
@@ -141,6 +141,7 @@ struct scmi_xfer {
 };
 
 struct scmi_xfer_ops;
+struct scmi_proto_helpers_ops;
 
 /**
  * struct scmi_protocol_handle  - Reference to an initialized protocol instance
@@ -165,11 +166,25 @@ struct scmi_xfer_ops;
 struct scmi_protocol_handle {
 	struct device *dev;
 	const struct scmi_xfer_ops *xops;
+	const struct scmi_proto_helpers_ops *hops;
 	int (*set_priv)(const struct scmi_protocol_handle *ph, void *priv);
 	void *(*get_priv)(const struct scmi_protocol_handle *ph);
 };
 
 /**
+ * struct scmi_proto_helpers_ops  - References to common protocol helpers
+ * @extended_name_get: A common helper function to retrieve extended naming
+ *		       for the specified resource using the specified command.
+ *		       Result is returned as a NULL terminated string in the
+ *		       pre-allocated area pointed to by @name with maximum
+ *		       capacity of @len bytes.
+ */
+struct scmi_proto_helpers_ops {
+	int (*extended_name_get)(const struct scmi_protocol_handle *ph,
+				 u8 cmd_id, u32 res_id, char *name, size_t len);
+};
+
+/**
  * struct scmi_xfer_ops  - References to the core SCMI xfer operations.
  * @version_get: Get this version protocol.
  * @xfer_get_init: Initialize one struct xfer if any xfer slot is free.