leds: trigger: use inline functions instead of macros

Macros are used in case that an inline function doesn't work.
Otherwise, use an empty inline function.

(a) Case of !CONFIG_LEDS_TRIGGERS
Following macros are replaced with inline functions.
  led_trigger_register_simple()
  led_trigger_unregister_simple()
  led_trigger_event()
To make inline types, the structure, 'led_trigger' should be defined.
This structure has no member at all.

(b) Case of !CONFIG_LEDS_TRIGGER_IDE_DISK
ledtrig_ide_activity() macro is replaced with an inline function as well.

(c) DEFINE_LED_TRIGGER() and DEFINE_LED_TRIGGER_GLOBAL()
Struct 'led_trigger' is defined both cases, with CONFIG_LEDS_TRIGGERS and
without CONFIG_LEDS_TRIGGERS.
Those macros are moved out of CONFIG_LED_TRIGGERS because of no-dependency
on CONFIG_LEDS_TRIGGERS.

(d) Fix build errors in mmc-core driver
After replacing macros with inline functions, following build errors occur.
(condition: CONFIG_LEDS_TRIGGERS is not set)

  drivers/mmc/core/core.c: In function 'mmc_request_done':
  drivers/mmc/core/core.c:164:25: error: 'struct mmc_host' has no member named 'led'
  drivers/mmc/core/core.c: In function 'mmc_start_request':
  drivers/mmc/core/core.c:254:24: error: 'struct mmc_host' has no member named 'led'
  make[3]: *** [drivers/mmc/core/core.o] Error 1

The reason of these errors is non-existent member variable, 'led'.
It is only valid when CONFIG_LEDS_TRIGGERS is set.
But now, it can be used without this dependency.
To fix build errors, member 'led' is always used without its config option in
'include/linux/mmc/host.h'.
Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

include/linux/leds.h

@@ -142,6 +142,10 @@ extern void led_set_brightness(struct led_classdev *led_cdev,
 /*
  * LED Triggers
  */
+/* Registration functions for simple triggers */
+#define DEFINE_LED_TRIGGER(x)		static struct led_trigger *x;
+#define DEFINE_LED_TRIGGER_GLOBAL(x)	struct led_trigger *x;
+
 #ifdef CONFIG_LEDS_TRIGGERS
 
 #define TRIG_NAME_MAX 50
@@ -164,9 +168,6 @@ struct led_trigger {
 extern int led_trigger_register(struct led_trigger *trigger);
 extern void led_trigger_unregister(struct led_trigger *trigger);
 
-/* Registration functions for simple triggers */
-#define DEFINE_LED_TRIGGER(x)		static struct led_trigger *x;
-#define DEFINE_LED_TRIGGER_GLOBAL(x)	struct led_trigger *x;
 extern void led_trigger_register_simple(const char *name,
 				struct led_trigger **trigger);
 extern void led_trigger_unregister_simple(struct led_trigger *trigger);
@@ -199,20 +200,22 @@ extern void led_trigger_rename_static(const char *name,
 
 #else
 
-/* Triggers aren't active - null macros */
-#define DEFINE_LED_TRIGGER(x)
-#define DEFINE_LED_TRIGGER_GLOBAL(x)
-#define led_trigger_register_simple(x, y) do {} while(0)
-#define led_trigger_unregister_simple(x) do {} while(0)
-#define led_trigger_event(x, y) do {} while(0)
+/* Trigger has no members */
+struct led_trigger {};
 
-#endif
+/* Trigger inline empty functions */
+static inline void led_trigger_register_simple(const char *name,
+					struct led_trigger **trigger) {}
+static inline void led_trigger_unregister_simple(struct led_trigger *trigger) {}
+static inline void led_trigger_event(struct led_trigger *trigger,
+				enum led_brightness event) {}
+#endif /* CONFIG_LEDS_TRIGGERS */
 
 /* Trigger specific functions */
 #ifdef CONFIG_LEDS_TRIGGER_IDE_DISK
 extern void ledtrig_ide_activity(void);
 #else
-#define ledtrig_ide_activity() do {} while(0)
+static inline void ledtrig_ide_activity(void) {}
 #endif
 
 /*

include/linux/mmc/host.h

@@ -341,9 +341,7 @@ struct mmc_host {
 
 	mmc_pm_flag_t		pm_flags;	/* requested pm features */
 
-#ifdef CONFIG_LEDS_TRIGGERS
 	struct led_trigger	*led;		/* activity led */
-#endif
 
 #ifdef CONFIG_REGULATOR
 	bool			regulator_enabled; /* regulator state */