Atmel AT91 I2C Two-Wire interface (TWI)

modulename: i2c-at91.ko

configname: CONFIG_I2C_AT91

Linux Kernel Configuration
└─>Device Drivers
└─>I2C support
└─>I2C Hardware Bus support
└─>Atmel AT91 I2C Two-Wire interface (TWI)
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
This supports the use of the I2C interface on Atmel AT91
processors.

A serious problem is that there is no documented way to issue
repeated START conditions for more than two messages, as needed
to support combined I2C messages. Use the i2c-gpio driver
unless your system can cope with this limitation.

Caution! at91rm9200, at91sam9261, at91sam9260, at91sam9263 devices
don't have clock stretching in transmission mode. For that reason,
you can encounter underrun issues causing premature stop sendings if
the latency to fill the transmission register is too long. If you
are facing this situation, use the i2c-gpio driver.

source code: