firmware: arm_scmi: add initial support for performance protocol

The performance protocol is intended for the performance management of
group(s) of device(s) that run in the same performance domain. It
includes even the CPUs. A performance domain is defined by a set of
devices that always have to run at the same performance level.
For example, a set of CPUs that share a voltage domain, and have a
common frequency control, is said to be in the same performance domain.

The commands in this protocol provide functionality to describe the
protocol version, describe various attribute flags, set and get the
performance level of a domain. It also supports discovery of the list
of performance levels supported by a performance domain, and the
properties of each performance level.

This patch adds basic support for the performance protocol.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/Makefile

 obj-y	= scmi-bus.o scmi-driver.o scmi-protocols.o
 scmi-bus-y = bus.o
 scmi-driver-y = driver.o
-scmi-protocols-y = base.o
+scmi-protocols-y = base.o perf.o

drivers/firmware/arm_scmi/common.h

@@ -19,6 +19,7 @@
 #define PROTOCOL_REV_MAJOR(x)	((x) >> PROTOCOL_REV_MINOR_BITS)
 #define PROTOCOL_REV_MINOR(x)	((x) & PROTOCOL_REV_MINOR_MASK)
 #define MAX_PROTOCOLS_IMP	16
+#define MAX_OPPS		16
 
 enum scmi_common_cmd {
 	PROTOCOL_VERSION = 0x0,

include/linux/scmi_protocol.h

@@ -33,15 +33,57 @@ struct scmi_revision_info {
 	char sub_vendor_id[SCMI_MAX_STR_SIZE];
 };
 
+struct scmi_handle;
+
+/**
+ * struct scmi_perf_ops - represents the various operations provided
+ *	by SCMI Performance Protocol
+ *
+ * @limits_set: sets limits on the performance level of a domain
+ * @limits_get: gets limits on the performance level of a domain
+ * @level_set: sets the performance level of a domain
+ * @level_get: gets the performance level of a domain
+ * @device_domain_id: gets the scmi domain id for a given device
+ * @get_transition_latency: gets the DVFS transition latency for a given device
+ * @add_opps_to_device: adds all the OPPs for a given device
+ * @freq_set: sets the frequency for a given device using sustained frequency
+ *	to sustained performance level mapping
+ * @freq_get: gets the frequency for a given device using sustained frequency
+ *	to sustained performance level mapping
+ */
+struct scmi_perf_ops {
+	int (*limits_set)(const struct scmi_handle *handle, u32 domain,
+			  u32 max_perf, u32 min_perf);
+	int (*limits_get)(const struct scmi_handle *handle, u32 domain,
+			  u32 *max_perf, u32 *min_perf);
+	int (*level_set)(const struct scmi_handle *handle, u32 domain,
+			 u32 level);
+	int (*level_get)(const struct scmi_handle *handle, u32 domain,
+			 u32 *level);
+	int (*device_domain_id)(struct device *dev);
+	int (*get_transition_latency)(const struct scmi_handle *handle,
+				      struct device *dev);
+	int (*add_opps_to_device)(const struct scmi_handle *handle,
+				  struct device *dev);
+	int (*freq_set)(const struct scmi_handle *handle, u32 domain,
+			unsigned long rate);
+	int (*freq_get)(const struct scmi_handle *handle, u32 domain,
+			unsigned long *rate);
+};
+
 /**
  * struct scmi_handle - Handle returned to ARM SCMI clients for usage.
  *
  * @dev: pointer to the SCMI device
  * @version: pointer to the structure containing SCMI version information
+ * @perf_ops: pointer to set of performance protocol operations
  */
 struct scmi_handle {
 	struct device *dev;
 	struct scmi_revision_info *version;
+	struct scmi_perf_ops *perf_ops;
+	/* for protocol internal use */
+	void *perf_priv;
 };
 
 enum scmi_std_protocol {