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authorLinus Torvalds <torvalds@linux-foundation.org>2012-06-05 13:55:31 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2012-06-05 13:55:31 -0400
commit690efa08e268a36df170bee79df93a9649c3f217 (patch)
tree16fa1ccd5cefd3db92201908ca2a1051f86799db /Documentation
parent5698e9180cb70020bbf8b613174afe6308f902b0 (diff)
parentae58d1e406986f31d1e88b32f5ac601506c196d8 (diff)
Merge branch 'i2c-embedded/for-current' of git://git.pengutronix.de/git/wsa/linux
Pull embedded i2c update from Wolfram Sang: "This only contains one new driver which had multiple dependencies (pinctrl, i2c-mux-rework, new devm_* functions), so I decided to wait for rc1. Plus, it had to wait a little for the ack of a devicetree maintainer since the bindings were not trivial enough for me to pass through. So, given that, I hope there is still something like the "new driver rule", so we could have the driver in 3.5 and people can start using it. That would make merging support for some boards easier for 3.6 since the dependency on this driver is gone then." * 'i2c-embedded/for-current' of git://git.pengutronix.de/git/wsa/linux: i2c: Add generic I2C multiplexer using pinctrl API
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1Pinctrl-based I2C Bus Mux
2
3This binding describes an I2C bus multiplexer that uses pin multiplexing to
4route the I2C signals, and represents the pin multiplexing configuration
5using the pinctrl device tree bindings.
6
7 +-----+ +-----+
8 | dev | | dev |
9 +------------------------+ +-----+ +-----+
10 | SoC | | |
11 | /----|------+--------+
12 | +---+ +------+ | child bus A, on first set of pins
13 | |I2C|---|Pinmux| |
14 | +---+ +------+ | child bus B, on second set of pins
15 | \----|------+--------+--------+
16 | | | | |
17 +------------------------+ +-----+ +-----+ +-----+
18 | dev | | dev | | dev |
19 +-----+ +-----+ +-----+
20
21Required properties:
22- compatible: i2c-mux-pinctrl
23- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
24 port is connected to.
25
26Also required are:
27
28* Standard pinctrl properties that specify the pin mux state for each child
29 bus. See ../pinctrl/pinctrl-bindings.txt.
30
31* Standard I2C mux properties. See mux.txt in this directory.
32
33* I2C child bus nodes. See mux.txt in this directory.
34
35For each named state defined in the pinctrl-names property, an I2C child bus
36will be created. I2C child bus numbers are assigned based on the index into
37the pinctrl-names property.
38
39The only exception is that no bus will be created for a state named "idle". If
40such a state is defined, it must be the last entry in pinctrl-names. For
41example:
42
43 pinctrl-names = "ddc", "pta", "idle" -> ddc = bus 0, pta = bus 1
44 pinctrl-names = "ddc", "idle", "pta" -> Invalid ("idle" not last)
45 pinctrl-names = "idle", "ddc", "pta" -> Invalid ("idle" not last)
46
47Whenever an access is made to a device on a child bus, the relevant pinctrl
48state will be programmed into hardware.
49
50If an idle state is defined, whenever an access is not being made to a device
51on a child bus, the idle pinctrl state will be programmed into hardware.
52
53If an idle state is not defined, the most recently used pinctrl state will be
54left programmed into hardware whenever no access is being made of a device on
55a child bus.
56
57Example:
58
59 i2cmux {
60 compatible = "i2c-mux-pinctrl";
61 #address-cells = <1>;
62 #size-cells = <0>;
63
64 i2c-parent = <&i2c1>;
65
66 pinctrl-names = "ddc", "pta", "idle";
67 pinctrl-0 = <&state_i2cmux_ddc>;
68 pinctrl-1 = <&state_i2cmux_pta>;
69 pinctrl-2 = <&state_i2cmux_idle>;
70
71 i2c@0 {
72 reg = <0>;
73 #address-cells = <1>;
74 #size-cells = <0>;
75
76 eeprom {
77 compatible = "eeprom";
78 reg = <0x50>;
79 };
80 };
81
82 i2c@1 {
83 reg = <1>;
84 #address-cells = <1>;
85 #size-cells = <0>;
86
87 eeprom {
88 compatible = "eeprom";
89 reg = <0x50>;
90 };
91 };
92 };
93