1Microchip MCP2308/MCP23S08/MCP23017/MCP23S17 driver for
28-/16-bit I/O expander with serial interface (I2C/SPI)
3
4Required properties:
5- compatible : Should be
6    - "mcp,mcp23s08" (DEPRECATED) for  8 GPIO SPI version
7    - "mcp,mcp23s17" (DEPRECATED) for 16 GPIO SPI version
8    - "mcp,mcp23008" (DEPRECATED) for  8 GPIO I2C version or
9    - "mcp,mcp23017" (DEPRECATED) for 16 GPIO I2C version of the chip
10
11    - "microchip,mcp23s08" for  8 GPIO SPI version
12    - "microchip,mcp23s17" for 16 GPIO SPI version
13    - "microchip,mcp23s18" for 16 GPIO SPI version
14    - "microchip,mcp23008" for  8 GPIO I2C version or
15    - "microchip,mcp23017" for 16 GPIO I2C version of the chip
16    - "microchip,mcp23018" for 16 GPIO I2C version
17    NOTE: Do not use the old mcp prefix any more. It is deprecated and will be
18    removed.
19- #gpio-cells : Should be two.
20  - first cell is the pin number
21  - second cell is used to specify flags as described in
22    'Documentation/devicetree/bindings/gpio/gpio.txt'. Allowed values defined by
23    'include/dt-bindings/gpio/gpio.h' (e.g. GPIO_ACTIVE_LOW).
24- gpio-controller : Marks the device node as a GPIO controller.
25- reg : For an address on its bus. I2C uses this a the I2C address of the chip.
26        SPI uses this to specify the chipselect line which the chip is
27        connected to. The driver and the SPI variant of the chip support
28        multiple chips on the same chipselect. Have a look at
29        microchip,spi-present-mask below.
30
31Required device specific properties (only for SPI chips):
32- mcp,spi-present-mask (DEPRECATED)
33- microchip,spi-present-mask : This is a present flag, that makes only sense for SPI
34        chips - as the name suggests. Multiple SPI chips can share the same
35        SPI chipselect. Set a bit in bit0-7 in this mask to 1 if there is a
36        chip connected with the corresponding spi address set. For example if
37        you have a chip with address 3 connected, you have to set bit3 to 1,
38        which is 0x08. mcp23s08 chip variant only supports bits 0-3. It is not
39        possible to mix mcp23s08 and mcp23s17 on the same chipselect. Set at
40        least one bit to 1 for SPI chips.
41    NOTE: Do not use the old mcp prefix any more. It is deprecated and will be
42    removed.
43- spi-max-frequency = The maximum frequency this chip is able to handle
44
45Optional properties:
46- #interrupt-cells : Should be two.
47  - first cell is the pin number
48  - second cell is used to specify flags.
49- interrupt-controller: Marks the device node as a interrupt controller.
50- drive-open-drain: Sets the ODR flag in the IOCON register. This configures
51        the IRQ output as open drain active low.
52
53Optional device specific properties:
54- microchip,irq-mirror: Sets the mirror flag in the IOCON register. Devices
55        with two interrupt outputs (these are the devices ending with 17 and
56        those that have 16 IOs) have two IO banks: IO 0-7 form bank 1 and
57        IO 8-15 are bank 2. These chips have two different interrupt outputs:
58        One for bank 1 and another for bank 2. If irq-mirror is set, both
59        interrupts are generated regardless of the bank that an input change
60        occurred on. If it is not set, the interrupt are only generated for the
61        bank they belong to.
62        On devices with only one interrupt output this property is useless.
63- microchip,irq-active-high: Sets the INTPOL flag in the IOCON register. This
64        configures the IRQ output polarity as active high.
65
66Example I2C (with interrupt):
67gpiom1: gpio@20 {
68        compatible = "microchip,mcp23017";
69        gpio-controller;
70        #gpio-cells = <2>;
71        reg = <0x20>;
72
73        interrupt-parent = <&gpio1>;
74        interrupts = <17 IRQ_TYPE_LEVEL_LOW>;
75        interrupt-controller;
76        #interrupt-cells=<2>;
77        microchip,irq-mirror;
78};
79
80Example SPI:
81gpiom1: gpio@0 {
82        compatible = "microchip,mcp23s17";
83        gpio-controller;
84        #gpio-cells = <2>;
85        spi-present-mask = <0x01>;
86        reg = <0>;
87        spi-max-frequency = <1000000>;
88};
89
90Pull-up configuration
91=====================
92
93If pins are used as output, they can also be configured with pull-ups. This is
94done with pinctrl.
95
96Please refer file <devicetree/bindings/pinctrl/pinctrl-bindings.txt>
97for details of the common pinctrl bindings used by client devices,
98including the meaning of the phrase "pin configuration node".
99
100Optional Pinmux properties:
101--------------------------
102Following properties are required if default setting of pins are required
103at boot.
104- pinctrl-names: A pinctrl state named per <pinctrl-bindings.txt>.
105- pinctrl[0...n]: Properties to contain the phandle for pinctrl states per
106		<pinctrl-bindings.txt>.
107
108The pin configurations are defined as child of the pinctrl states node. Each
109sub-node have following properties:
110
111Required properties:
112------------------
113- pins: List of pins. Valid values of pins properties are:
114		      gpio0 ... gpio7 for the devices with 8 GPIO pins and
115		      gpio0 ... gpio15 for the devices with 16 GPIO pins.
116
117Optional properties:
118-------------------
119The following optional property is defined in the pinmux DT binding document
120<pinctrl-bindings.txt>. Absence of this property will leave the configuration
121in its default state.
122	bias-pull-up
123
124Example with pinctrl to pull-up output pins:
125gpio21: gpio@21 {
126	compatible = "microchip,mcp23017";
127	gpio-controller;
128	#gpio-cells = <0x2>;
129	reg = <0x21>;
130	interrupt-parent = <&socgpio>;
131	interrupts = <0x17 0x8>;
132	interrupt-names = "mcp23017@21 irq";
133	interrupt-controller;
134	#interrupt-cells = <0x2>;
135	microchip,irq-mirror;
136	pinctrl-names = "default";
137	pinctrl-0 = <&i2cgpio0irq &gpio21pullups>;
138
139	gpio21pullups: pinmux {
140		pins =	"gpio0", "gpio1", "gpio2", "gpio3",
141			"gpio4", "gpio5", "gpio6", "gpio7",
142			"gpio8", "gpio9", "gpio10", "gpio11",
143			"gpio12", "gpio13", "gpio14", "gpio15";
144		bias-pull-up;
145	};
146};
147