2011-03-31 21:48:18

by Simon Wood

[permalink] [raw]
Subject: Poulsbo I2C - /dev/i2c not seen when loading i2c-dev

Hi all,
I'm hoping that someone here can help. I am trying to get userland access
to the I2C bus(es) on an embedded system, however recent kernels (ie.
2.6.38) are not 'loading' any buses when I 'modprobe i2c-dev'.

Going back to ?2.6.32? I am able to see 1 bus, and 'i2cdetect 0' shows a
single device sitting at address 0x69 (which I believe to EEPROM on the
wifi card... not confirmed).


The board is built around the Poulsbo and therefore using the 'i2c-isch'
driver.

Reviewing the schematic I see that there are several buses, each going to
individual components:
IT8516 U5/110+111 -> LTC1760 U6/18+22 [battery charger ? 0x1A/0x12]
IT8516 U5/115+116 -> W83L771 U60/8+7 [thermal sensor ? 0x18??]
IT8516 U5/117+118 -> LSM303DLH U64/19+20 [accel/compass ? 0x19]
POULSBO U2/G37+H38 -> PCI Express Socket

I am a little dismayed by the comment in 'i2c-isch.c' which suggest it can
handle only one i2c bus at any time.
--
/*
Supports:
Intel SCH chipsets (AF82US15W, AF82US15L, AF82UL11L)
Note: we assume there can only be one device, with one SMBus interface.
*/
--

This seems to correlate to these comments:
http://www.linuxforums.org/forum/programming-scripting/175147-smbus-intel-sch-us15w.html

Can anyone confirm whether this is actually the case, and whether it is
possible to configure it to use a different controller address. One would
expect this to be a module option I guess, however it doesn't seem to take
any.

Many thanks in advance,
Simon.