| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame^] | 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 | } |