ACPI: PRM: Add acpi_prm_handler_available()

Add a helper function to check if a PRM handler/module is present.

This can be used during init time by code that depends on a particular
handler. If the handler is not present, then the code does not need to
be loaded.

Signed-off-by: Yazen Ghannam <[e-mail]>
Signed-off-by: Borislav Petkov (AMD) <[e-mail]>
Reviewed-by: "Mario Limonciello (AMD)" <[e-mail]>
Acked-by: "Rafael J. Wysocki (Intel)" <[e-mail]>
Link: https://patch.msgid.link/all/[e-mail]

drivers/acpi/prmt.c

···
 	return (struct prm_handler_info *) find_guid_info(guid, GET_HANDLER);
 }
 
+bool acpi_prm_handler_available(const guid_t *guid)
+{
+	return find_prm_handler(guid) && find_prm_module(guid);
+}
+EXPORT_SYMBOL_GPL(acpi_prm_handler_available);
+
 /* In-coming PRM commands */
 
 #define PRM_CMD_RUN_SERVICE		0

include/linux/prmt.h

···
 
 #ifdef CONFIG_ACPI_PRMT
 void init_prmt(void);
+bool acpi_prm_handler_available(const guid_t *handler_guid);
 int acpi_call_prm_handler(guid_t handler_guid, void *param_buffer);
 #else
 static inline void init_prmt(void) { }
+static inline bool acpi_prm_handler_available(const guid_t *handler_guid) { return false; }
 static inline int acpi_call_prm_handler(guid_t handler_guid, void *param_buffer)
 {
 	return -EOPNOTSUPP;