Lines Matching +full:a +full:- +full:b

1 .. SPDX-License-Identifier: GPL-2.0
11 -----------
13 An I2C Address Translator (ATR) is a device with an I2C slave parent
16 with a modified slave address. The address used on the parent bus is
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
26 The ATR functionality can be provided by a chip with many other features.
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
33 ATR maintains a table of currently assigned alias and uses it to modify
36 A typical example follows.
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
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
70    messages with address 0x20, forwards to adapter A
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
94 -------------------------------------
96 .. kernel-doc:: include/linux/i2c-atr.h