1* Freescale MXS Pin Controller
2
3The pins controlled by mxs pin controller are organized in banks, each bank
4has 32 pins.  Each pin has 4 multiplexing functions, and generally, the 4th
5function is GPIO.  The configuration on the pins includes drive strength,
6voltage and pull-up.
7
8Required properties:
9- compatible: "fsl,imx23-pinctrl" or "fsl,imx28-pinctrl"
10- reg: Should contain the register physical address and length for the
11  pin controller.
12
13Please refer to pinctrl-bindings.txt in this directory for details of the
14common pinctrl bindings used by client devices.
15
16The node of mxs pin controller acts as a container for an arbitrary number of
17subnodes.  Each of these subnodes represents some desired configuration for
18a group of pins, and only affects those parameters that are explicitly listed.
19In other words, a subnode that describes a drive strength parameter implies no
20information about pull-up. For this reason, even seemingly boolean values are
21actually tristates in this binding: unspecified, off, or on. Unspecified is
22represented as an absent property, and off/on are represented as integer
23values 0 and 1.
24
25Those subnodes under mxs pin controller node will fall into two categories.
26One is to set up a group of pins for a function, both mux selection and pin
27configurations, and it's called group node in the binding document.   The other
28one is to adjust the pin configuration for some particular pins that need a
29different configuration than what is defined in group node.  The binding
30document calls this type of node config node.
31
32On mxs, there is no hardware pin group. The pin group in this binding only
33means a group of pins put together for particular peripheral to work in
34particular function, like SSP0 functioning as mmc0-8bit.  That said, the
35group node should include all the pins needed for one function rather than
36having these pins defined in several group nodes.  It also means each of
37"pinctrl-*" phandle in client device node should only have one group node
38pointed in there, while the phandle can have multiple config node referenced
39there to adjust configurations for some pins in the group.
40
41Required subnode-properties:
42- fsl,pinmux-ids: An integer array.  Each integer in the array specify a pin
43  with given mux function, with bank, pin and mux packed as below.
44
45    [15..12] : bank number
46    [11..4]  : pin number
47    [3..0]   : mux selection
48
49  This integer with mux selection packed is used as an entity by both group
50  and config nodes to identify a pin.  The mux selection in the integer takes
51  effects only on group node, and will get ignored by driver with config node,
52  since config node is only meant to set up pin configurations.
53
54  Valid values for these integers are listed below.
55
56- reg: Should be the index of the group nodes for same function.  This property
57  is required only for group nodes, and should not be present in any config
58  nodes.
59
60Optional subnode-properties:
61- fsl,drive-strength: Integer.
62    0: MXS_DRIVE_4mA
63    1: MXS_DRIVE_8mA
64    2: MXS_DRIVE_12mA
65    3: MXS_DRIVE_16mA
66- fsl,voltage: Integer.
67    0: MXS_VOLTAGE_LOW  - 1.8 V
68    1: MXS_VOLTAGE_HIGH - 3.3 V
69- fsl,pull-up: Integer.
70    0: MXS_PULL_DISABLE - Disable the internal pull-up
71    1: MXS_PULL_ENABLE  - Enable the internal pull-up
72
73Note that when enabling the pull-up, the internal pad keeper gets disabled.
74Also, some pins doesn't have a pull up, in that case, setting the fsl,pull-up
75will only disable the internal pad keeper.
76
77Examples:
78
79pinctrl@80018000 {
80	#address-cells = <1>;
81	#size-cells = <0>;
82	compatible = "fsl,imx28-pinctrl";
83	reg = <0x80018000 2000>;
84
85	mmc0_8bit_pins_a: mmc0-8bit@0 {
86		reg = <0>;
87		fsl,pinmux-ids = <
88			MX28_PAD_SSP0_DATA0__SSP0_D0
89			MX28_PAD_SSP0_DATA1__SSP0_D1
90			MX28_PAD_SSP0_DATA2__SSP0_D2
91			MX28_PAD_SSP0_DATA3__SSP0_D3
92			MX28_PAD_SSP0_DATA4__SSP0_D4
93			MX28_PAD_SSP0_DATA5__SSP0_D5
94			MX28_PAD_SSP0_DATA6__SSP0_D6
95			MX28_PAD_SSP0_DATA7__SSP0_D7
96			MX28_PAD_SSP0_CMD__SSP0_CMD
97			MX28_PAD_SSP0_DETECT__SSP0_CARD_DETECT
98			MX28_PAD_SSP0_SCK__SSP0_SCK
99		>;
100		fsl,drive-strength = <MXS_DRIVE_4mA>;
101		fsl,voltage = <MXS_VOLTAGE_HIGH>;
102		fsl,pull-up = <MXS_PULL_ENABLE>;
103	};
104
105	mmc_cd_cfg: mmc-cd-cfg {
106		fsl,pinmux-ids = <MX28_PAD_SSP0_DETECT__SSP0_CARD_DETECT>;
107		fsl,pull-up = <MXS_PULL_DISABLE>;
108	};
109
110	mmc_sck_cfg: mmc-sck-cfg {
111		fsl,pinmux-ids = <MX28_PAD_SSP0_SCK__SSP0_SCK>;
112		fsl,drive-strength = <MXS_DRIVE_12mA>;
113		fsl,pull-up = <MXS_PULL_DISABLE>;
114	};
115};
116
117In this example, group node mmc0-8bit defines a group of pins for mxs SSP0
118to function as a 8-bit mmc device, with 8mA, 3.3V and pull-up configurations
119applied on all these pins.  And config nodes mmc-cd-cfg and mmc-sck-cfg are
120adjusting the configuration for pins card-detection and clock from what group
121node mmc0-8bit defines.  Only the configuration properties to be adjusted need
122to be listed in the config nodes.
123
124Valid values for i.MX28/i.MX23 pinmux-id are defined in
125arch/arm/boot/dts/imx28-pinfunc.h and arch/arm/boot/dts/imx23-pinfunc.h.
126The definitions for the padconfig properties can be found in
127arch/arm/boot/dts/mxs-pinfunc.h.
128