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+*ST pin controller.
+
+Each multi-function pin is controlled, driven and routed through the
+PIO multiplexing block. Each pin supports GPIO functionality (ALT0)
+and multiple alternate functions(ALT1 - ALTx) that directly connect
+the pin to different hardware blocks.
+
+When a pin is in GPIO mode, Output Enable (OE), Open Drain(OD), and
+Pull Up (PU) are driven by the related PIO block.
+
+ST pinctrl driver controls PIO multiplexing block and also interacts with
+gpio driver to configure a pin.
+
+Required properties: (PIO multiplexing block)
+- compatible : should be "st,<SOC>-<pio-block>-pinctrl"
+ like st,stih415-sbc-pinctrl, st,stih415-front-pinctrl and so on.
+- gpio-controller : Indicates this device is a GPIO controller
+- #gpio-cells : Should be one. The first cell is the pin number.
+- st,retime-pin-mask : Should be mask to specify which pins can be retimed.
+ If the property is not present, it is assumed that all the pins in the
+ bank are capable of retiming. Retiming is mainly used to improve the
+ IO timing margins of external synchronous interfaces.
+- st,bank-name : Should be a name string for this bank as
+ specified in datasheet.
+- st,syscfg : Should be a phandle of the syscfg node.
+
+Example:
+ pin-controller-sbc {
+ #address-cells = <1>;
+ #size-cells = <1>;
+ compatible = "st,stih415-sbc-pinctrl";
+ st,syscfg = <&syscfg_sbc>;
+ ranges = <0 0xfe610000 0x5000>;
+ PIO0: gpio@fe610000 {
+ gpio-controller;
+ #gpio-cells = <1>;
+ reg = <0 0x100>;
+ st,bank-name = "PIO0";
+ };
+ ...
+ pin-functions nodes follow...
+ };
+
+
+Contents of function subnode node:
+----------------------
+Required properties for pin configuration node:
+- st,pins : Child node with list of pins with configuration.
+
+Below is the format of how each pin conf should look like.
+
+<bank offset mux mode rt_type rt_delay rt_clk>
+
+Every PIO is represented with 4-7 parameters depending on retime configuration.
+Each parameter is explained as below.
+
+-bank : Should be bank phandle to which this PIO belongs.
+-offset : Offset in the PIO bank.
+-mux : Should be alternate function number associated this pin.
+ Use same numbers from datasheet.
+-mode :pin configuration is selected from one of the below values.
+ IN
+ IN_PU
+ OUT
+ BIDIR
+ BIDIR_PU
+
+-rt_type Retiming Configuration for the pin.
+ Possible retime configuration are:
+
+ ------- -------------
+ value args
+ ------- -------------
+ NICLK <delay> <clk>
+ ICLK_IO <delay> <clk>
+ BYPASS <delay>
+ DE_IO <delay> <clk>
+ SE_ICLK_IO <delay> <clk>
+ SE_NICLK_IO <delay> <clk>
+
+- delay is retime delay in pico seconds as mentioned in data sheet.
+
+- rt_clk :clk to be use for retime.
+ Possible values are:
+ CLK_A
+ CLK_B
+ CLK_C
+ CLK_D
+
+Example of mmcclk pin which is a bi-direction pull pu with retime config
+as non inverted clock retimed with CLK_B and delay of 0 pico seconds:
+
+pin-controller {
+ ...
+ mmc0 {
+ pinctrl_mmc: mmc {
+ st,pins {
+ mmcclk = <&PIO13 4 ALT4 BIDIR_PU NICLK 0 CLK_B>;
+ ...
+ };
+ };
+ ...
+ };
+};
+
+sdhci0:sdhci@fe810000{
+ ...
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_mmc>;
+};
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