FreeBSD/Linux Kernel Cross Reference
sys/contrib/device-tree/Bindings/pinctrl/pinctrl-st.txt

     *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.
    
    GPIO bank can have one of the two possible types of interrupt-wirings.
    
    First type is via irqmux, single interrupt is used by multiple gpio banks. This
    reduces number of overall interrupts numbers required. All these banks belong to
    a single pincontroller.
                      _________
                     |         |----> [gpio-bank (n)    ]
                     |         |----> [gpio-bank (n + 1)]
            [irqN]-- | irq-mux |----> [gpio-bank (n + 2)]
                     |         |----> [gpio-bank (...  )]
                     |_________|----> [gpio-bank (n + 7)]
    
    Second type has a dedicated interrupt per gpio bank.
    
            [irqN]----> [gpio-bank (n)]
    
    
    Pin controller node:
    Required properties:
    - compatible    : should be "st,stih407-<pio-block>-pinctrl"
    - st,syscfg             : Should be a phandle of the syscfg node.
    - 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.
    - ranges : defines mapping between pin controller node (parent) to gpio-bank
      node (children).
    
    Optional properties:
    - interrupts    : Interrupt number of the irqmux. If the interrupt is shared
      with other gpio banks via irqmux.
      a irqline and gpio banks.
    - reg           : irqmux memory resource. If irqmux is present.
    - reg-names     : irqmux resource should be named as "irqmux".
    
    GPIO controller/bank node.
    Required properties:
    - gpio-controller : Indicates this device is a GPIO controller
    - #gpio-cells     : Must be two.
         - First cell: specifies the pin number inside the controller
         - Second cell: specifies whether the pin is logically inverted.
           - 0 = active high
           - 1 = active low
    - st,bank-name    : Should be a name string for this bank as specified in
      datasheet.
    
    Optional properties:
    - interrupts    : Interrupt number for this gpio bank. If there is a dedicated
      interrupt wired up for this gpio bank.
    
    - interrupt-controller : Indicates this device is a interrupt controller. GPIO
      bank can be an interrupt controller iff one of the interrupt type either via
    irqmux or a dedicated interrupt per bank is specified.
    
    - #interrupt-cells: the value of this property should be 2.
         - First Cell: represents the external gpio interrupt number local to the
           gpio interrupt space of the controller.
         - Second Cell: flags to identify the type of the interrupt
           - 1 = rising edge triggered
           - 2 = falling edge triggered
           - 3 = rising and falling edge triggered
           - 4 = high level triggered
           - 8 = low level triggered
    for related macros look in:
    include/dt-bindings/interrupt-controller/irq.h
    
    Example:
            pin-controller-sbc {
                    #address-cells = <1>;
                    #size-cells = <1>;
                    compatible = "st,stih407-sbc-pinctrl";
                    st,syscfg = <&syscfg_sbc>;
                    reg = <0x0961f080 0x4>;
                    reg-names = "irqmux";
                    interrupts = <GIC_SPI 188 IRQ_TYPE_NONE>;
                    interrupt-names = "irqmux";
                    ranges = <0 0x09610000 0x6000>;
    
                    pio0: gpio@9610000 {
                            gpio-controller;
                            #gpio-cells = <2>;
                            interrupt-controller;
                            #interrupt-cells = <2>;
                            reg = <0x0 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{
           ...
           interrupt-parent = <&pio3>;
           #interrupt-cells = <2>;
           interrupts = <3 IRQ_TYPE_LEVEL_HIGH>; /* Interrupt line via PIO3-3 */
           interrupt-names = "card-detect";
           pinctrl-names = "default";
           pinctrl-0       = <&pinctrl_mmc>;
   };

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