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Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/devicetree/bindings/pinctrl/pinctrl-st.txt | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/pinctrl/pinctrl-st.txt b/Documentation/devicetree/bindings/pinctrl/pinctrl-st.txt new file mode 100644 index 00000000000..05bf82a07df --- /dev/null +++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-st.txt @@ -0,0 +1,110 @@ +*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>; +}; |