firmware: arm_scmi: add scmi protocol bus to enumerate protocol devices

The SCMI specification encompasses various protocols. However, not every
protocol has to be present on a given platform/implementation as not
every protocol is relevant for it.

Furthermore, the platform chooses which protocols it exposes to a given
agent. The only protocol that must be implemented is the base protocol.
The base protocol is used by an agent to discover which protocols are
available to it.

In order to enumerate the discovered implemented protocols, this patch
adds support for a separate scmi protocol bus. It also adds mechanism to
register support for different protocols.

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

1 files changed, 64 insertions, 0 deletions

diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
index 08fcc1dd0276..464086b9d8c5 100644
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -4,6 +4,7 @@
  *
  * Copyright (C) 2018 ARM Ltd.
  */
+#include <linux/device.h>
 #include <linux/types.h>
 
 #define SCMI_MAX_STR_SIZE	16
@@ -51,3 +52,66 @@ enum scmi_std_protocol {
 	SCMI_PROTOCOL_CLOCK = 0x14,
 	SCMI_PROTOCOL_SENSOR = 0x15,
 };
+
+struct scmi_device {
+	u32 id;
+	u8 protocol_id;
+	struct device dev;
+	struct scmi_handle *handle;
+};
+
+#define to_scmi_dev(d) container_of(d, struct scmi_device, dev)
+
+struct scmi_device *
+scmi_device_create(struct device_node *np, struct device *parent, int protocol);
+void scmi_device_destroy(struct scmi_device *scmi_dev);
+
+struct scmi_device_id {
+	u8 protocol_id;
+};
+
+struct scmi_driver {
+	const char *name;
+	int (*probe)(struct scmi_device *sdev);
+	void (*remove)(struct scmi_device *sdev);
+	const struct scmi_device_id *id_table;
+
+	struct device_driver driver;
+};
+
+#define to_scmi_driver(d) container_of(d, struct scmi_driver, driver)
+
+#ifdef CONFIG_ARM_SCMI_PROTOCOL
+int scmi_driver_register(struct scmi_driver *driver,
+			 struct module *owner, const char *mod_name);
+void scmi_driver_unregister(struct scmi_driver *driver);
+#else
+static inline int
+scmi_driver_register(struct scmi_driver *driver, struct module *owner,
+		     const char *mod_name)
+{
+	return -EINVAL;
+}
+
+static inline void scmi_driver_unregister(struct scmi_driver *driver) {}
+#endif /* CONFIG_ARM_SCMI_PROTOCOL */
+
+#define scmi_register(driver) \
+	scmi_driver_register(driver, THIS_MODULE, KBUILD_MODNAME)
+#define scmi_unregister(driver) \
+	scmi_driver_unregister(driver)
+
+/**
+ * module_scmi_driver() - Helper macro for registering a scmi driver
+ * @__scmi_driver: scmi_driver structure
+ *
+ * Helper macro for scmi drivers to set up proper module init / exit
+ * functions.  Replaces module_init() and module_exit() and keeps people from
+ * printing pointless things to the kernel log when their driver is loaded.
+ */
+#define module_scmi_driver(__scmi_driver)	\
+	module_driver(__scmi_driver, scmi_register, scmi_unregister)
+
+typedef int (*scmi_prot_init_fn_t)(struct scmi_handle *);
+int scmi_protocol_register(int protocol_id, scmi_prot_init_fn_t fn);
+void scmi_protocol_unregister(int protocol_id);