[linux-sunxi] PATH[1/3] ARM: axp20x_usb_power.c add device tree configuration options for REG 30H: VBUS-IPSOUT

The AXP20X chips have a configuration register "REG 30H: VBUS-IPSOUT Power Path Management" that provide USB power supply protection.
The current axp20x_usb_power.c provides support only for reading those values.

From the datasheet:
In order not to affect the USB communication, VBUS is always working under Voltage-Limit mode by default. In this mode, AXP209 ensures that VBUS voltage remains above a configurable reference voltage VHOLD which can meet the USB specification. The default VHOLD is 4.4V, adjustable in Reg30H [5:3] register. If the system has limit on current obtained from USB VBUS, a current-limit mode is provided (See REG30H[1] register), with 900mA/500mA/100mA (Reg30H [0]) selectable.

The following entries are added in the axp209.dtsi file: vhold-enable, vhold-set and ibus-limit
The chosen default values are the AXP20X reset values, as described in the data sheet.

Signed-off-by: Ene Alexandru <redacted>


---
diff -uprN -X linux-sunxi-original/Documentation/dontdiff linux-sunxi-original/arch/arm/boot/dts/axp209.dtsi linux-sunxi/arch/arm/boot/dts/axp209.dtsi

--- linux-sunxi-original/arch/arm/boot/dts/axp209.dtsi         2016-05-11 09:21:47.470923679 +0200
+++ linux-sunxi/arch/arm/boot/dts/axp209.dtsi     2016-05-10 18:45:32.795158651 +0200

@@ -98,5 +98,8 @@
           usb_power_supply: usb_power_supply {
                       compatible = "x-powers,axp202-usb-power-supply";
                       status = "disabled";
+                      vhold-enable = <0x01>;
+                      vhold-set = <0x04>;
+                      ibus-limit = <0x01>;
           };

};