1 ==========================
2 Kernel driver i2c-mux-gpio
3 ==========================
4
5 Author: Peter Korsgaard <peter.korsgaard@barco.
6
7 Description
8 -----------
9
10 i2c-mux-gpio is an i2c mux driver providing ac
11 from a master I2C bus and a hardware MUX contr
12
13 E.G.::
14
15 ---------- ---------- Bus segm
16 | | SCL/SDA | |---------
17 | |------------| |
18 | | | | Bus segm
19 | Linux | GPIO 1..N | MUX |---------
20 | |------------| |
21 | | | | Bus segm
22 | | | |---------
23 ---------- ----------
24
25 SCL/SDA of the master I2C bus is multiplexed t
26 according to the settings of the GPIO pins 1..
27
28 Usage
29 -----
30
31 i2c-mux-gpio uses the platform bus, so you nee
32 platform_device with the platform_data pointin
33 i2c_mux_gpio_platform_data with the I2C adapte
34 bus, the number of bus segments to create and
35 to control it. See include/linux/platform_data
36
37 E.G. something like this for a MUX providing 4
38 controlled through 3 GPIO pins::
39
40 #include <linux/platform_data/i2c-mux-gpio.h
41 #include <linux/platform_device.h>
42
43 static const unsigned myboard_gpiomux_gpios[
44 AT91_PIN_PC26, AT91_PIN_PC25, AT91_PIN
45 };
46
47 static const unsigned myboard_gpiomux_values
48 0, 1, 2, 3
49 };
50
51 static struct i2c_mux_gpio_platform_data myb
52 .parent = 1,
53 .base_nr = 2, /* optional */
54 .values = myboard_gpiomux_valu
55 .n_values = ARRAY_SIZE(myboard_g
56 .gpios = myboard_gpiomux_gpio
57 .n_gpios = ARRAY_SIZE(myboard_g
58 .idle = 4, /* optional */
59 };
60
61 static struct platform_device myboard_i2cmux
62 .name = "i2c-mux-gpio",
63 .id = 0,
64 .dev = {
65 .platform_data = &myboard_i2c
66 },
67 };
68
69 If you don't know the absolute GPIO pin number
70 you can instead provide a chip name (.chip_nam
71 numbers, and the i2c-mux-gpio driver will do t
72 including deferred probing if the GPIO chip is
73 available.
74
75 Device Registration
76 -------------------
77
78 When registering your i2c-mux-gpio device, you
79 of any GPIO pin it uses as the device ID. This
80 instance has a different ID.
81
82 Alternatively, if you don't need a stable devi
83 pass PLATFORM_DEVID_AUTO as the device ID, and
84 assign a dynamic ID to your device. If you do
85 GPIO pin numbers at registration time, this is
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