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[releases.git] / Documentation / firmware-guide / acpi / i2c-muxes.rst
1 .. SPDX-License-Identifier: GPL-2.0
2
3 ==============
4 ACPI I2C Muxes
5 ==============
6
7 Describing an I2C device hierarchy that includes I2C muxes requires an ACPI
8 Device () scope per mux channel.
9
10 Consider this topology::
11
12     +------+   +------+
13     | SMB1 |-->| MUX0 |--CH00--> i2c client A (0x50)
14     |      |   | 0x70 |--CH01--> i2c client B (0x50)
15     +------+   +------+
16
17 which corresponds to the following ASL::
18
19     Device (SMB1)
20     {
21         Name (_HID, ...)
22         Device (MUX0)
23         {
24             Name (_HID, ...)
25             Name (_CRS, ResourceTemplate () {
26                 I2cSerialBus (0x70, ControllerInitiated, I2C_SPEED,
27                             AddressingMode7Bit, "^SMB1", 0x00,
28                             ResourceConsumer,,)
29             }
30
31             Device (CH00)
32             {
33                 Name (_ADR, 0)
34
35                 Device (CLIA)
36                 {
37                     Name (_HID, ...)
38                     Name (_CRS, ResourceTemplate () {
39                         I2cSerialBus (0x50, ControllerInitiated, I2C_SPEED,
40                                     AddressingMode7Bit, "^CH00", 0x00,
41                                     ResourceConsumer,,)
42                     }
43                 }
44             }
45
46             Device (CH01)
47             {
48                 Name (_ADR, 1)
49
50                 Device (CLIB)
51                 {
52                     Name (_HID, ...)
53                     Name (_CRS, ResourceTemplate () {
54                         I2cSerialBus (0x50, ControllerInitiated, I2C_SPEED,
55                                     AddressingMode7Bit, "^CH01", 0x00,
56                                     ResourceConsumer,,)
57                     }
58                 }
59             }
60         }
61     }