FreeBSD/Linux Kernel Cross Reference
sys/contrib/device-tree/Bindings/pinctrl/fsl,mxs-pinctrl.txt

     * Freescale MXS Pin Controller
     
     The pins controlled by mxs pin controller are organized in banks, each bank
     has 32 pins.  Each pin has 4 multiplexing functions, and generally, the 4th
     function is GPIO.  The configuration on the pins includes drive strength,
     voltage and pull-up.
     
     Required properties:
     - compatible: "fsl,imx23-pinctrl" or "fsl,imx28-pinctrl"
    - reg: Should contain the register physical address and length for the
      pin controller.
    
    Please refer to pinctrl-bindings.txt in this directory for details of the
    common pinctrl bindings used by client devices.
    
    The node of mxs pin controller acts as a container for an arbitrary number of
    subnodes.  Each of these subnodes represents some desired configuration for
    a group of pins, and only affects those parameters that are explicitly listed.
    In other words, a subnode that describes a drive strength parameter implies no
    information about pull-up. For this reason, even seemingly boolean values are
    actually tristates in this binding: unspecified, off, or on. Unspecified is
    represented as an absent property, and off/on are represented as integer
    values 0 and 1.
    
    Those subnodes under mxs pin controller node will fall into two categories.
    One is to set up a group of pins for a function, both mux selection and pin
    configurations, and it's called group node in the binding document.   The other
    one is to adjust the pin configuration for some particular pins that need a
    different configuration than what is defined in group node.  The binding
    document calls this type of node config node.
    
    On mxs, there is no hardware pin group. The pin group in this binding only
    means a group of pins put together for particular peripheral to work in
    particular function, like SSP0 functioning as mmc0-8bit.  That said, the
    group node should include all the pins needed for one function rather than
    having these pins defined in several group nodes.  It also means each of
    "pinctrl-*" phandle in client device node should only have one group node
    pointed in there, while the phandle can have multiple config node referenced
    there to adjust configurations for some pins in the group.
    
    Required subnode-properties:
    - fsl,pinmux-ids: An integer array.  Each integer in the array specify a pin
      with given mux function, with bank, pin and mux packed as below.
    
        [15..12] : bank number
        [11..4]  : pin number
        [3..0]   : mux selection
    
      This integer with mux selection packed is used as an entity by both group
      and config nodes to identify a pin.  The mux selection in the integer takes
      effects only on group node, and will get ignored by driver with config node,
      since config node is only meant to set up pin configurations.
    
      Valid values for these integers are listed below.
    
    - reg: Should be the index of the group nodes for same function.  This property
      is required only for group nodes, and should not be present in any config
      nodes.
    
    Optional subnode-properties:
    - fsl,drive-strength: Integer.
        0: MXS_DRIVE_4mA
        1: MXS_DRIVE_8mA
        2: MXS_DRIVE_12mA
        3: MXS_DRIVE_16mA
    - fsl,voltage: Integer.
        0: MXS_VOLTAGE_LOW  - 1.8 V
        1: MXS_VOLTAGE_HIGH - 3.3 V
    - fsl,pull-up: Integer.
        0: MXS_PULL_DISABLE - Disable the internal pull-up
        1: MXS_PULL_ENABLE  - Enable the internal pull-up
    
    Note that when enabling the pull-up, the internal pad keeper gets disabled.
    Also, some pins doesn't have a pull up, in that case, setting the fsl,pull-up
    will only disable the internal pad keeper.
    
    Examples:
    
    pinctrl@80018000 {
            #address-cells = <1>;
            #size-cells = <0>;
            compatible = "fsl,imx28-pinctrl";
            reg = <0x80018000 2000>;
    
            mmc0_8bit_pins_a: mmc0-8bit@0 {
                    reg = <0>;
                    fsl,pinmux-ids = <
                            MX28_PAD_SSP0_DATA0__SSP0_D0
                            MX28_PAD_SSP0_DATA1__SSP0_D1
                            MX28_PAD_SSP0_DATA2__SSP0_D2
                            MX28_PAD_SSP0_DATA3__SSP0_D3
                            MX28_PAD_SSP0_DATA4__SSP0_D4
                            MX28_PAD_SSP0_DATA5__SSP0_D5
                            MX28_PAD_SSP0_DATA6__SSP0_D6
                            MX28_PAD_SSP0_DATA7__SSP0_D7
                            MX28_PAD_SSP0_CMD__SSP0_CMD
                            MX28_PAD_SSP0_DETECT__SSP0_CARD_DETECT
                            MX28_PAD_SSP0_SCK__SSP0_SCK
                    >;
                   fsl,drive-strength = <MXS_DRIVE_4mA>;
                   fsl,voltage = <MXS_VOLTAGE_HIGH>;
                   fsl,pull-up = <MXS_PULL_ENABLE>;
           };
   
           mmc_cd_cfg: mmc-cd-cfg {
                   fsl,pinmux-ids = <MX28_PAD_SSP0_DETECT__SSP0_CARD_DETECT>;
                   fsl,pull-up = <MXS_PULL_DISABLE>;
           };
   
           mmc_sck_cfg: mmc-sck-cfg {
                   fsl,pinmux-ids = <MX28_PAD_SSP0_SCK__SSP0_SCK>;
                   fsl,drive-strength = <MXS_DRIVE_12mA>;
                   fsl,pull-up = <MXS_PULL_DISABLE>;
           };
   };
   
   In this example, group node mmc0-8bit defines a group of pins for mxs SSP0
   to function as a 8-bit mmc device, with 8mA, 3.3V and pull-up configurations
   applied on all these pins.  And config nodes mmc-cd-cfg and mmc-sck-cfg are
   adjusting the configuration for pins card-detection and clock from what group
   node mmc0-8bit defines.  Only the configuration properties to be adjusted need
   to be listed in the config nodes.
   
   Valid values for i.MX28/i.MX23 pinmux-id are defined in
   arch/arm/boot/dts/imx28-pinfunc.h and arch/arm/boot/dts/imx23-pinfunc.h.
   The definitions for the padconfig properties can be found in
   arch/arm/boot/dts/mxs-pinfunc.h.

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