Spreadtrum EIC controller bindings The EIC is the abbreviation of external interrupt controller, which can be used only in input mode. The Spreadtrum platform has 2 EIC controllers, one is in digital chip, and another one is in PMIC. The digital chip EIC controller contains 4 sub-modules: EIC-debounce, EIC-latch, EIC-async and EIC-sync. But the PMIC EIC controller contains only one EIC-debounce sub- module. The EIC-debounce sub-module provides up to 8 source input signal connections. A debounce mechanism is used to capture the input signals' stable status (millisecond resolution) and a single-trigger mechanism is introduced into this sub-module to enhance the input event detection reliability. In addition, this sub-module's clock can be shut off automatically to reduce power dissipation. Moreover the debounce range is from 1ms to 4s with a step size of 1ms. The input signal will be ignored if it is asserted for less than 1 ms. The EIC-latch sub-module is used to latch some special power down signals and generate interrupts, since the EIC-latch does not depend on the APB clock to capture signals. The EIC-async sub-module uses a 32kHz clock to capture the short signals (microsecond resolution) to generate interrupts by level or edge trigger. The EIC-sync is similar with GPIO's input function, which is a synchronized signal input register. It can generate interrupts by level or edge trigger when detecting input signals. Required properties: - compatible: Should be one of the following: "sprd,sc9860-eic-debounce", "sprd,sc9860-eic-latch", "sprd,sc9860-eic-async", "sprd,sc9860-eic-sync", "sprd,sc2731-eic". - reg: Define the base and range of the I/O address space containing the GPIO controller registers. - gpio-controller: Marks the device node as a GPIO controller. - #gpio-cells: Should be <2>. The first cell is the gpio number and the second cell is used to specify optional parameters. - interrupt-controller: Marks the device node as an interrupt controller. - #interrupt-cells: Should be <2>. Specifies the number of cells needed to encode interrupt source. - interrupts: Should be the port interrupt shared by all the gpios. Example: eic_debounce: gpio@40210000 { compatible = "sprd,sc9860-eic-debounce"; reg = <0 0x40210000 0 0x80>; gpio-controller; #gpio-cells = <2>; interrupt-controller; #interrupt-cells = <2>; interrupts = ; }; eic_latch: gpio@40210080 { compatible = "sprd,sc9860-eic-latch"; reg = <0 0x40210080 0 0x20>; gpio-controller; #gpio-cells = <2>; interrupt-controller; #interrupt-cells = <2>; interrupts = ; }; eic_async: gpio@402100a0 { compatible = "sprd,sc9860-eic-async"; reg = <0 0x402100a0 0 0x20>; gpio-controller; #gpio-cells = <2>; interrupt-controller; #interrupt-cells = <2>; interrupts = ; }; eic_sync: gpio@402100c0 { compatible = "sprd,sc9860-eic-sync"; reg = <0 0x402100c0 0 0x20>; gpio-controller; #gpio-cells = <2>; interrupt-controller; #interrupt-cells = <2>; interrupts = ; }; pmic_eic: gpio@300 { compatible = "sprd,sc2731-eic"; reg = <0x300>; interrupt-parent = <&sc2731_pmic>; interrupts = <5 IRQ_TYPE_LEVEL_HIGH>; gpio-controller; #gpio-cells = <2>; interrupt-controller; #interrupt-cells = <2>; };