add backlight in driver folder

drivers/video/backlight/rk2818_backlight.h

@@ -0,0 +1,41 @@
+/*
+ *  linux/include/asm-arm/arch-rockchip/pwm.h
+ *
+ */
+
+#ifndef __ASM_ARCH_RK2818_BACKLIGHT_H
+#define __ASM_ARCH_RK2818_BACKLIGHT_H
+
+///PWM_CTRL
+#define PWM_DIV2            (0<<9)
+#define PWM_DIV4            (1<<9)
+#define PWM_DIV8            (2<<9)
+#define PWM_DIV16           (3<<9)
+#define PWM_DIV32           (4<<9)
+#define PWM_DIV64           (5<<9)
+#define PWM_DIV128          (6<<9)
+#define PWM_DIV256          (7<<9)
+#define PWM_DIV512          (8<<9)
+#define PWM_DIV1024         (9<<9)
+
+#define PWM_CAPTURE         (1<<8)
+#define PWM_RESET           (1<<7)
+#define PWM_INTCLR          (1<<6)
+#define PWM_INTEN           (1<<5)
+#define PWM_SINGLE          (1<<6)
+
+#define PWM_ENABLE          (1<<3)
+#define PWM_TIME_EN         (1)
+
+
+#define PWM_REG_CNTR         0x00
+#define PWM_REG_HRC          0x04 
+#define PWM_REG_LRC          0x08
+#define PWM_REG_CTRL         0x0c
+
+
+#define PWM_DIV              PWM_DIV2
+#define PWM_APB_PRE_DIV      1000
+#define BL_STEP              255
+
+#endif	/* __ASM_ARCH_RK2818_BACKLIGHT_H */