48 lines
1.9 KiB
Plaintext
48 lines
1.9 KiB
Plaintext
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Microchip MCP2308/MCP23S08/MCP23017/MCP23S17 driver for
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8-/16-bit I/O expander with serial interface (I2C/SPI)
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Required properties:
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- compatible : Should be
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- "mcp,mcp23s08" for 8 GPIO SPI version
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- "mcp,mcp23s17" for 16 GPIO SPI version
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- "mcp,mcp23008" for 8 GPIO I2C version or
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- "mcp,mcp23017" for 16 GPIO I2C version of the chip
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- #gpio-cells : Should be two.
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- first cell is the pin number
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- second cell is used to specify flags. Flags are currently unused.
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- gpio-controller : Marks the device node as a GPIO controller.
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- reg : For an address on its bus. I2C uses this a the I2C address of the chip.
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SPI uses this to specify the chipselect line which the chip is
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connected to. The driver and the SPI variant of the chip support
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multiple chips on the same chipselect. Have a look at
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mcp,spi-present-mask below.
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Required device specific properties (only for SPI chips):
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- mcp,spi-present-mask : This is a present flag, that makes only sense for SPI
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chips - as the name suggests. Multiple SPI chips can share the same
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SPI chipselect. Set a bit in bit0-7 in this mask to 1 if there is a
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chip connected with the corresponding spi address set. For example if
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you have a chip with address 3 connected, you have to set bit3 to 1,
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which is 0x08. mcp23s08 chip variant only supports bits 0-3. It is not
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possible to mix mcp23s08 and mcp23s17 on the same chipselect. Set at
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least one bit to 1 for SPI chips.
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- spi-max-frequency = The maximum frequency this chip is able to handle
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Example I2C:
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gpiom1: gpio@20 {
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compatible = "mcp,mcp23017";
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gpio-controller;
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#gpio-cells = <2>;
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reg = <0x20>;
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};
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Example SPI:
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gpiom1: gpio@0 {
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compatible = "mcp,mcp23s17";
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gpio-controller;
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#gpio-cells = <2>;
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spi-present-mask = <0x01>;
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reg = <0>;
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spi-max-frequency = <1000000>;
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};
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