* Freescale IMX27 IOMUX Controller

Required properties:
- compatible: "fsl,imx27-iomuxc"

The iomuxc driver node should define subnodes containing of pinctrl configuration subnodes.

Required properties for pin configuration node:
- fsl,pins: three integers array, represents a group of pins mux and config
  setting. The format is fsl,pins = <PIN MUX_ID CONFIG>.

  PIN is an integer between 0 and 0xbf. imx27 has 6 ports with 32 configurable
  configurable pins each. PIN is PORT * 32 + PORT_PIN, PORT_PIN is the pin
  number on the specific port (between 0 and 31).

  MUX_ID is
    function + (direction << 2) + (gpio_oconf << 4) + (gpio_iconfa << 8) + (gpio_iconfb << 10)

      function value is used to select the pin function.
      Possible values:
          0 - Primary function
          1 - Alternate function
          2 - GPIO
      Registers: GIUS (GPIO In Use), GPR (General Purpose Register)

      direction defines the data direction of the pin.
      Possible values:
          0 - Input
          1 - Output
      Register: DDIR

      gpio_oconf configures the gpio submodule output signal. This does not
      have any effect unless GPIO function is selected. A/B/C_IN are output
      signals of function blocks A,B and C. Specific function blocks are
      described in the reference manual.
      Possible values:
          0 - A_IN
          1 - B_IN
          2 - C_IN
          3 - Data Register
      Registers: OCR1, OCR2

      gpio_iconfa/b configures the gpio submodule input to functionblocks A and
      B. GPIO function should be selected if this is configured.
      Possible values:
          0 - GPIO_IN
          1 - Interrupt Status Register
          2 - Pulldown
          3 - Pullup
      Registers ICONFA1, ICONFA2, ICONFB1 and ICONFB2

  CONFIG can be 0 or 1, meaning Pullup disable/enable.


Example:

iomuxc: iomuxc@10015000 {
	compatible = "fsl,imx27-iomuxc";
	reg = <0x10015000 0x600>;

	uart {
		pinctrl_uart1: uart-1 {
			fsl,pins = <
				0x8c 0x004 0x0 /* UART1_TXD__UART1_TXD */
				0x8d 0x000 0x0 /* UART1_RXD__UART1_RXD */
				0x8e 0x004 0x0 /* UART1_CTS__UART1_CTS */
				0x8f 0x000 0x0 /* UART1_RTS__UART1_RTS */
			>;
		};

		...
	};
};


For convenience there are macros defined in imx27-pinfunc.h which provide PIN
and MUX_ID. They are structured as MX27_PAD_<Pad name>__<Signal name>. The names
are defined in the i.MX27 reference manual.

The above example using macros:

iomuxc: iomuxc@10015000 {
	compatible = "fsl,imx27-iomuxc";
	reg = <0x10015000 0x600>;

	uart {
		pinctrl_uart1: uart-1 {
			fsl,pins = <
				MX27_PAD_UART1_TXD__UART1_TXD 0x0
				MX27_PAD_UART1_RXD__UART1_RXD 0x0
				MX27_PAD_UART1_CTS__UART1_CTS 0x0
				MX27_PAD_UART1_RTS__UART1_RTS 0x0
			>;
		};

		...
	};
};