gpio: rcar: Add more register documentation

Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-rcar.c

@@ -39,18 +39,18 @@ struct gpio_rcar_priv {
 	struct irq_chip irq_chip;
 };
 
-#define IOINTSEL 0x00
-#define INOUTSEL 0x04
-#define OUTDT 0x08
-#define INDT 0x0c
-#define INTDT 0x10
-#define INTCLR 0x14
-#define INTMSK 0x18
-#define MSKCLR 0x1c
-#define POSNEG 0x20
-#define EDGLEVEL 0x24
-#define FILONOFF 0x28
-#define BOTHEDGE 0x4c
+#define IOINTSEL 0x00	/* General IO/Interrupt Switching Register */
+#define INOUTSEL 0x04	/* General Input/Output Switching Register */
+#define OUTDT 0x08	/* General Output Register */
+#define INDT 0x0c	/* General Input Register */
+#define INTDT 0x10	/* Interrupt Display Register */
+#define INTCLR 0x14	/* Interrupt Clear Register */
+#define INTMSK 0x18	/* Interrupt Mask Register */
+#define MSKCLR 0x1c	/* Interrupt Mask Clear Register */
+#define POSNEG 0x20	/* Positive/Negative Logic Select Register */
+#define EDGLEVEL 0x24	/* Edge/level Select Register */
+#define FILONOFF 0x28	/* Chattering Prevention On/Off Register */
+#define BOTHEDGE 0x4c	/* One Edge/Both Edge Select Register */
 
 #define RCAR_MAX_GPIO_PER_BANK		32