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Diffstat (limited to 'Documentation/devicetree/bindings/gpio/gpio-mcp23s08.txt')
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/gpio-mcp23s08.txt | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/gpio/gpio-mcp23s08.txt b/Documentation/devicetree/bindings/gpio/gpio-mcp23s08.txt new file mode 100644 index 000000000..f3332b9a8 --- /dev/null +++ b/Documentation/devicetree/bindings/gpio/gpio-mcp23s08.txt @@ -0,0 +1,85 @@ +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,mcp23008" for 8 GPIO I2C version or + - "microchip,mcp23017" for 16 GPIO I2C version of the chip + 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. Flags are currently unused. +- 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. +NOTE: The interrupt functionality is only supported for i2c versions of the +chips. The spi chips can also do the interrupts, but this is not supported by +the linux driver yet. + +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>; + spi-present-mask = <0x01>; + reg = <0>; + spi-max-frequency = <1000000>; +}; |