pwm: sunxi: add support for PWM found on Allwinner A64

This commit adds basic support for PWM found on Allwinner A64.
It can be used for pwm_backlight driver (e.g. for Pinebook)

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
diff --git a/arch/arm/include/asm/arch-sunxi/gpio.h b/arch/arm/include/asm/arch-sunxi/gpio.h
index 3334fb5..e4fe54d 100644
--- a/arch/arm/include/asm/arch-sunxi/gpio.h
+++ b/arch/arm/include/asm/arch-sunxi/gpio.h
@@ -172,6 +172,7 @@
 #define SUN8I_GPD_SDC1		3
 #define SUNXI_GPD_LCD0		2
 #define SUNXI_GPD_LVDS0		3
+#define SUNXI_GPD_PWM		2
 
 #define SUN5I_GPE_SDC2		3
 #define SUN8I_GPE_TWI2		3
diff --git a/arch/arm/include/asm/arch-sunxi/pwm.h b/arch/arm/include/asm/arch-sunxi/pwm.h
index 47eb433..dca283c 100644
--- a/arch/arm/include/asm/arch-sunxi/pwm.h
+++ b/arch/arm/include/asm/arch-sunxi/pwm.h
@@ -10,8 +10,15 @@
 #define SUNXI_PWM_CH0_PERIOD		(SUNXI_PWM_BASE + 4)
 
 #define SUNXI_PWM_CTRL_PRESCALE0(x)	((x) & 0xf)
+#define SUNXI_PWM_CTRL_PRESCALE0_MASK	0xf
 #define SUNXI_PWM_CTRL_ENABLE0		(0x5 << 4)
 #define SUNXI_PWM_CTRL_POLARITY0(x)	((x) << 5)
+#define SUNXI_PWM_CTRL_CH0_ACT_STA	BIT(5)
+#define SUNXI_PWM_CTRL_CLK_GATE		BIT(6)
+
+#define SUNXI_PWM_CH0_PERIOD_MAX	(0xffff)
+#define SUNXI_PWM_CH0_PERIOD_PRD(x)	((x & 0xffff) << 16)
+#define SUNXI_PWM_CH0_PERIOD_DUTY(x)	((x) & 0xffff)
 
 #define SUNXI_PWM_PERIOD_80PCT		0x04af03c0
 
@@ -30,4 +37,9 @@
 #define SUNXI_PWM_MUX			SUN8I_GPH_PWM
 #endif
 
+struct sunxi_pwm {
+	u32 ctrl;
+	u32 ch0_period;
+};
+
 #endif