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+* ZTE ZX Pin Controller
+
+The pin controller on ZTE ZX platforms is kinda of hybrid. It consists of
+a main controller and an auxiliary one. For example, on ZX296718 SoC, the
+main controller is TOP_PMM and the auxiliary one is AON_IOCFG. Both
+controllers work together to control pin multiplexing and configuration in
+the way illustrated as below.
+
+
+ GMII_RXD3 ---+
+ |
+ DVI1_HS ---+----------------------------- GMII_RXD3 (TOP pin)
+ |
+ BGPIO16 ---+ ^
+ | pinconf
+ ^ |
+ | pinmux |
+ | |
+
+ TOP_PMM (main) AON_IOCFG (aux)
+
+ | | |
+ | pinmux | |
+ | pinmux v |
+ v | pinconf
+ KEY_ROW2 ---+ v
+ PORT1_LCD_TE ---+ |
+ | AGPIO10 ---+------ KEY_ROW2 (AON pin)
+ I2S0_DOUT3 ---+ |
+ |-----------------------+
+ PWM_OUT3 ---+
+ |
+ VGA_VS1 ---+
+
+
+For most of pins like GMII_RXD3 in the figure, the pinmux function is
+controlled by TOP_PMM block only, and this type of pins are meant by term
+'TOP pins'. For pins like KEY_ROW2, the pinmux is controlled by both
+TOP_PMM and AON_IOCFG blocks, as the available multiplexing functions for
+the pin spread in both controllers. This type of pins are called 'AON pins'.
+Though pinmux implementation is quite different, pinconf is same for both
+types of pins. Both are controlled by auxiliary controller, i.e. AON_IOCFG
+on ZX296718.
+
+Required properties:
+- compatible: should be "zte,zx296718-pmm".
+- reg: the register physical address and length.
+- zte,auxiliary-controller: phandle to the auxiliary pin controller which
+ implements pinmux for AON pins and pinconf for all pins.
+
+The following pin configuration are supported. Please refer to
+pinctrl-bindings.txt in this directory for more details of the common
+pinctrl bindings used by client devices.
+
+- bias-pull-up
+- bias-pull-down
+- drive-strength
+- input-enable
+- slew-rate
+
+Examples:
+
+iocfg: pin-controller@119000 {
+ compatible = "zte,zx296718-iocfg";
+ reg = <0x119000 0x1000>;
+};
+
+pmm: pin-controller@1462000 {
+ compatible = "zte,zx296718-pmm";
+ reg = <0x1462000 0x1000>;
+ zte,auxiliary-controller = <&iocfg>;
+};
+
+&pmm {
+ vga_pins: vga {
+ pins = "KEY_COL1", "KEY_COL2", "KEY_ROW1", "KEY_ROW2";
+ function = "VGA";
+ };
+};
+
+&vga {
+ pinctrl-names = "default";
+ pinctrl-0 = <&vga_pins>;
+ status = "okay";
+};