Lines Matching +full:i2c +full:- +full:bus

1 .. SPDX-License-Identifier: GPL-2.0
4 I2C Address Translators
11 -----------
13 An I2C Address Translator (ATR) is a device with an I2C slave parent
14 ("upstream") port and N I2C master child ("downstream") ports, and
16 with a modified slave address. The address used on the parent bus is
18 slave address of the child bus. Address translation is done by the
21 An ATR looks similar to an i2c-mux except:
22  - the address on the parent and child busses can be different
23  - there is normally no need to select the child port; the alias used on the
24    parent bus implies it
27 The kernel i2c-atr provides a helper to implement an ATR within a driver.
29 The ATR creates a new I2C "child" adapter on each child bus. Adding
30 devices on the child bus ends up in invoking the driver code to select
34 all I2C transactions directed to devices on the child buses.
41               .-----.   |
42   .-----.     |     |---+---- B
43   | CPU |--A--| ATR |
44   `-----'     |     |---+---- C
45               `-----'   |
50 A, B and C are three physical I2C busses, electrically independent from
51 each other. The ATR receives the transactions initiated on bus A and
52 propagates them on bus B or bus C or none depending on the device address
62    X (bus B, 0x10)   0x20
63    Y (bus C, 0x10)   0x30
68  - Slave X driver requests a transaction (on adapter B), slave address 0x10
69  - ATR driver finds slave X is on bus B and has alias 0x20, rewrites
71  - Physical I2C transaction on bus A, slave address 0x20
72  - ATR chip detects transaction on address 0x20, finds it in table,
73    propagates transaction on bus B with address translated to 0x10,
74    keeps clock stretched on bus A waiting for reply
75  - Slave X chip (on bus B) detects transaction at its own physical
77  - ATR chip stops clock stretching and forwards reply on bus A,
79  - ATR driver receives the reply, rewrites messages with address 0x10
81  - Slave X driver gets back the msgs[], with reply and address 0x10
93 I2C ATR functions and data structures
94 -------------------------------------
96 .. kernel-doc:: include/linux/i2c-atr.h