firmware: dmi: Add dmi_memdev_handle

Add a utility function dmi_memdev_handle() which returns the DMI
handle associated with a given memory slot. This will allow kernel
drivers to iterate over the memory slots.
Signed-off-by: Jean Delvare <jdelvare@suse.de>

drivers/firmware/dmi_scan.c

@@ -1151,3 +1151,19 @@ u8 dmi_memdev_type(u16 handle)
 	return 0x0;	/* Not a valid value */
 }
 EXPORT_SYMBOL_GPL(dmi_memdev_type);
+
+/**
+ *	dmi_memdev_handle - get the DMI handle of a memory slot
+ *	@slot: slot number
+ *
+ *	Return the DMI handle associated with a given memory slot, or %0xFFFF
+ *      if there is no such slot.
+ */
+u16 dmi_memdev_handle(int slot)
+{
+	if (dmi_memdev && slot >= 0 && slot < dmi_memdev_nr)
+		return dmi_memdev[slot].handle;
+
+	return 0xffff;	/* Not a valid value */
+}
+EXPORT_SYMBOL_GPL(dmi_memdev_handle);

include/linux/dmi.h

@@ -114,6 +114,7 @@ extern bool dmi_match(enum dmi_field f, const char *str);
 extern void dmi_memdev_name(u16 handle, const char **bank, const char **device);
 extern u64 dmi_memdev_size(u16 handle);
 extern u8 dmi_memdev_type(u16 handle);
+extern u16 dmi_memdev_handle(int slot);
 
 #else
 
@@ -144,6 +145,7 @@ static inline void dmi_memdev_name(u16 handle, const char **bank,
 		const char **device) { }
 static inline u64 dmi_memdev_size(u16 handle) { return ~0ul; }
 static inline u8 dmi_memdev_type(u16 handle) { return 0x0; }
+static inline u16 dmi_memdev_handle(int slot) { return 0xffff; }
 static inline const struct dmi_system_id *
 	dmi_first_match(const struct dmi_system_id *list) { return NULL; }