FreeBSD/Linux Kernel Cross Reference
sys/contrib/device-tree/Bindings/pinctrl/pinctrl-mcp23s08.txt

     Microchip MCP2308/MCP23S08/MCP23017/MCP23S17 driver for
     8-/16-bit I/O expander with serial interface (I2C/SPI)
     
     Required properties:
     - compatible : Should be
         - "mcp,mcp23s08" (DEPRECATED) for  8 GPIO SPI version
         - "mcp,mcp23s17" (DEPRECATED) for 16 GPIO SPI version
         - "mcp,mcp23008" (DEPRECATED) for  8 GPIO I2C version or
         - "mcp,mcp23017" (DEPRECATED) for 16 GPIO I2C version of the chip
    
        - "microchip,mcp23s08" for  8 GPIO SPI version
        - "microchip,mcp23s17" for 16 GPIO SPI version
        - "microchip,mcp23s18" for 16 GPIO SPI version
        - "microchip,mcp23008" for  8 GPIO I2C version or
        - "microchip,mcp23017" for 16 GPIO I2C version of the chip
        - "microchip,mcp23018" for 16 GPIO I2C version
        NOTE: Do not use the old mcp prefix any more. It is deprecated and will be
        removed.
    - #gpio-cells : Should be two.
      - first cell is the pin number
      - second cell is used to specify flags as described in
        'Documentation/devicetree/bindings/gpio/gpio.txt'. Allowed values defined by
        'include/dt-bindings/gpio/gpio.h' (e.g. GPIO_ACTIVE_LOW).
    - gpio-controller : Marks the device node as a GPIO controller.
    - reg : For an address on its bus. I2C uses this a the I2C address of the chip.
            SPI uses this to specify the chipselect line which the chip is
            connected to. The driver and the SPI variant of the chip support
            multiple chips on the same chipselect. Have a look at
            microchip,spi-present-mask below.
    
    Required device specific properties (only for SPI chips):
    - mcp,spi-present-mask (DEPRECATED)
    - microchip,spi-present-mask : This is a present flag, that makes only sense for SPI
            chips - as the name suggests. Multiple SPI chips can share the same
            SPI chipselect. Set a bit in bit0-7 in this mask to 1 if there is a
            chip connected with the corresponding spi address set. For example if
            you have a chip with address 3 connected, you have to set bit3 to 1,
            which is 0x08. mcp23s08 chip variant only supports bits 0-3. It is not
            possible to mix mcp23s08 and mcp23s17 on the same chipselect. Set at
            least one bit to 1 for SPI chips.
        NOTE: Do not use the old mcp prefix any more. It is deprecated and will be
        removed.
    - spi-max-frequency = The maximum frequency this chip is able to handle
    
    Optional properties:
    - #interrupt-cells : Should be two.
      - first cell is the pin number
      - second cell is used to specify flags.
    - interrupt-controller: Marks the device node as a interrupt controller.
    - drive-open-drain: Sets the ODR flag in the IOCON register. This configures
            the IRQ output as open drain active low.
    - reset-gpios: Corresponds to the active-low RESET# pin for the chip
    
    Optional device specific properties:
    - microchip,irq-mirror: Sets the mirror flag in the IOCON register. Devices
            with two interrupt outputs (these are the devices ending with 17 and
            those that have 16 IOs) have two IO banks: IO 0-7 form bank 1 and
            IO 8-15 are bank 2. These chips have two different interrupt outputs:
            One for bank 1 and another for bank 2. If irq-mirror is set, both
            interrupts are generated regardless of the bank that an input change
            occurred on. If it is not set, the interrupt are only generated for the
            bank they belong to.
            On devices with only one interrupt output this property is useless.
    - microchip,irq-active-high: Sets the INTPOL flag in the IOCON register. This
            configures the IRQ output polarity as active high.
    
    Example I2C (with interrupt):
    gpiom1: gpio@20 {
            compatible = "microchip,mcp23017";
            gpio-controller;
            #gpio-cells = <2>;
            reg = <0x20>;
    
            interrupt-parent = <&gpio1>;
            interrupts = <17 IRQ_TYPE_LEVEL_LOW>;
            interrupt-controller;
            #interrupt-cells=<2>;
            microchip,irq-mirror;
    };
    
    Example SPI:
    gpiom1: gpio@0 {
            compatible = "microchip,mcp23s17";
            gpio-controller;
            #gpio-cells = <2>;
            microchip,spi-present-mask = <0x01>;
            reg = <0>;
            spi-max-frequency = <1000000>;
    };
    
    Pull-up configuration
    =====================
    
    If pins are used as output, they can also be configured with pull-ups. This is
    done with pinctrl.
    
    Please refer file <devicetree/bindings/pinctrl/pinctrl-bindings.txt>
    for details of the common pinctrl bindings used by client devices,
    including the meaning of the phrase "pin configuration node".
   
   Optional Pinmux properties:
   --------------------------
   Following properties are required if default setting of pins are required
   at boot.
   - pinctrl-names: A pinctrl state named per <pinctrl-bindings.txt>.
   - pinctrl[0...n]: Properties to contain the phandle for pinctrl states per
                   <pinctrl-bindings.txt>.
   
   The pin configurations are defined as child of the pinctrl states node. Each
   sub-node have following properties:
   
   Required properties:
   ------------------
   - pins: List of pins. Valid values of pins properties are:
                         gpio0 ... gpio7 for the devices with 8 GPIO pins and
                         gpio0 ... gpio15 for the devices with 16 GPIO pins.
   
   Optional properties:
   -------------------
   The following optional property is defined in the pinmux DT binding document
   <pinctrl-bindings.txt>. Absence of this property will leave the configuration
   in its default state.
           bias-pull-up
   
   Example with pinctrl to pull-up output pins:
   gpio21: gpio@21 {
           compatible = "microchip,mcp23017";
           gpio-controller;
           #gpio-cells = <0x2>;
           reg = <0x21>;
           interrupt-parent = <&socgpio>;
           interrupts = <0x17 0x8>;
           interrupt-names = "mcp23017@21 irq";
           interrupt-controller;
           #interrupt-cells = <0x2>;
           microchip,irq-mirror;
           pinctrl-names = "default";
           pinctrl-0 = <&i2cgpio0irq>, <&gpio21pullups>;
           reset-gpios = <&gpio6 15 GPIO_ACTIVE_LOW>;
   
           gpio21pullups: pinmux {
                   pins =  "gpio0", "gpio1", "gpio2", "gpio3",
                           "gpio4", "gpio5", "gpio6", "gpio7",
                           "gpio8", "gpio9", "gpio10", "gpio11",
                           "gpio12", "gpio13", "gpio14", "gpio15";
                   bias-pull-up;
           };
   };

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