ath9k: add a helper to get the string representation of ath_bus_type

This can be used when the ath_bus_type has to be presented in a log
message or firmware filename.

Signed-off-by: Martin Blumenstingl <[e-mail]>
Signed-off-by: Kalle Valo <[e-mail]>

drivers/net/wireless/ath/ath.h

···
 }
 #endif
 
+extern const char *ath_bus_type_strings[];
+static inline const char *ath_bus_type_to_string(enum ath_bus_type bustype)
+{
+	return ath_bus_type_strings[bustype];
+}
+
 #endif /* ATH_H */

drivers/net/wireless/ath/main.c

···
 	va_end(args);
 }
 EXPORT_SYMBOL(ath_printk);
+
+const char *ath_bus_type_strings[] = {
+	[ATH_PCI] = "pci",
+	[ATH_AHB] = "ahb",
+	[ATH_USB] = "usb",
+};
+EXPORT_SYMBOL(ath_bus_type_strings);