| Lars Poeschel | 97ddb1c | 2013-04-04 12:02:02 +0200 | [diff] [blame] | 1 | Microchip MCP2308/MCP23S08/MCP23017/MCP23S17 driver for |
| 2 | 8-/16-bit I/O expander with serial interface (I2C/SPI) |
| 3 | |
| 4 | Required properties: |
| 5 | - compatible : Should be |
| 6 | - "mcp,mcp23s08" for 8 GPIO SPI version |
| 7 | - "mcp,mcp23s17" for 16 GPIO SPI version |
| 8 | - "mcp,mcp23008" for 8 GPIO I2C version or |
| 9 | - "mcp,mcp23017" for 16 GPIO I2C version of the chip |
| 10 | - #gpio-cells : Should be two. |
| 11 | - first cell is the pin number |
| 12 | - second cell is used to specify flags. Flags are currently unused. |
| 13 | - gpio-controller : Marks the device node as a GPIO controller. |
| 14 | - reg : For an address on its bus. I2C uses this a the I2C address of the chip. |
| 15 | SPI uses this to specify the chipselect line which the chip is |
| 16 | connected to. The driver and the SPI variant of the chip support |
| 17 | multiple chips on the same chipselect. Have a look at |
| 18 | mcp,spi-present-mask below. |
| 19 | |
| 20 | Required device specific properties (only for SPI chips): |
| 21 | - mcp,spi-present-mask : This is a present flag, that makes only sense for SPI |
| 22 | chips - as the name suggests. Multiple SPI chips can share the same |
| 23 | SPI chipselect. Set a bit in bit0-7 in this mask to 1 if there is a |
| 24 | chip connected with the corresponding spi address set. For example if |
| 25 | you have a chip with address 3 connected, you have to set bit3 to 1, |
| 26 | which is 0x08. mcp23s08 chip variant only supports bits 0-3. It is not |
| 27 | possible to mix mcp23s08 and mcp23s17 on the same chipselect. Set at |
| 28 | least one bit to 1 for SPI chips. |
| 29 | - spi-max-frequency = The maximum frequency this chip is able to handle |
| 30 | |
| 31 | Example I2C: |
| 32 | gpiom1: gpio@20 { |
| 33 | compatible = "mcp,mcp23017"; |
| 34 | gpio-controller; |
| 35 | #gpio-cells = <2>; |
| 36 | reg = <0x20>; |
| 37 | }; |
| 38 | |
| 39 | Example SPI: |
| 40 | gpiom1: gpio@0 { |
| 41 | compatible = "mcp,mcp23s17"; |
| 42 | gpio-controller; |
| 43 | #gpio-cells = <2>; |
| 44 | spi-present-mask = <0x01>; |
| 45 | reg = <0>; |
| 46 | spi-max-frequency = <1000000>; |
| 47 | }; |