UM0851 datasheet(80/245 Pages) STMICROELECTRONICS

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Communication device drivers

UM0851

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Doc ID 16604 Rev 2

Figure 20.

I2C framework architecture

4.5.3

I2C framework in linux

The I2C kernel code is broken up into a number of logical pieces: the I2C core, I2C bus

drivers, I2C algorithm drivers and I2C client drivers.

I2C core

The I2C core is a code base consisting of routines and data structures available to host

adapter drivers and client drivers. The core also provides a level of indirection that renders

client drivers independent of the host adapter, allowing them to work even if the client device

is used on a board that has a different I2C host adapter.

Device drivers for I2C host adapters

They fall in the realm of bus drivers and usually contain an adapter driver. The former uses

the latter to talk to the I2C bus. I2C host adapter code is provided by ST and the path is:

Refer to Linux-2.6.27/drivers/i2c/bus/spr_i2c_syn.c

Device drivers for I2C client devices

They are used for reading/writing to the slave device. I2C client device drivers for EEPROM

as an example are provided in the following path:

Refer to Linux-2.6.27/drivers/i2c/chips/eeprom.c

I2C-dev

They allow communication with the user space. Usually, I2C devices are controlled by a

kernel driver. But you can also access all devices on an adapter from the user space,

through the /dev interface. For this, you need to load the module i2c-dev. Each registered i2c

User space

Kernel space

Hardware

User application

I2C user mode

application

I2C client driver

(sys./dev)

I2C dev

I2C core layer

I2C controller driver

I2C controller

UM0851 Datasheet(PDF) 80 Page - STMicroelectronics