i2c on BF537 stamp

Which uClinux-dist release do you use?

It looks you either forget to enable I2C device interface kernel option or the i2c-bfin-twi driver.

Could you please check your kernel configuration under device drivers -> I2C support -> I2C hardware bus support?

hi Sonic,

thanks for your quick answer.

my uClinux-dist is:

blackfin-linux-dist-2010R1-RC5

I just recompiled the kernel with following settings:

{M} I2C support  ---> 

--- I2C support 

[*]   Enable compatibility bits for old user-space 

<M>   I2C device interface

[*]   Autoselect pertinent helper modules

I2C Hardware Bus support  --->

[ ]   I2C Core debugging messages

[ ]   I2C Algorithm debugging messages

[ ]   I2C Bus debugging messages

the compiled version is now:

root:/> version

kernel:    Linux release 2.6.34.7-ADI-2010R1, build #20 Mon Apr 9 15:48:54 CEST 2012

toolchain: bfin-uclinux-gcc release gcc version 4.3.5 (ADI-2010R1-RC4)

user-dist: release 2010R1, build #9 Mon Apr 9 15:48:35 CEST 2012

However I got the same result as before still without the link /dev/i2c-0:

root:/dev> ls -la

drwxr-xr-x    3 root     root             0 Jan 13 05:35 .

drwxr-xr-x   14 root     root             0 Jan  1  2007 ..

crw-rw----    1 root     root        5,   1 Jan 13 05:35 console

crw-rw----    1 root     root       10,  63 Jan 13 05:35 cpu_dma_latency

lrwxrwxrwx    1 root     root            13 Jan 13 05:35 fd -> /proc/self/fd

crw-rw----    1 root     root        1,   7 Jan 13 05:35 full

crw-rw----    1 root     root        1,  11 Jan 13 05:35 kmsg

srw-rw-rw-    1 root     root             0 Jan 13 05:35 log

-rw-r--r--    1 root     root             0 Jan 13 05:35 mdev.seq

crw-rw----    1 root     root        1,   1 Jan 13 05:35 mem

crw-rw----    1 root     root       10,  62 Jan 13 05:35 network_latency

crw-rw----    1 root     root       10,  61 Jan 13 05:35 network_throughput

crw-rw----    1 root     root        1,   3 Jan 13 05:35 null

crw-rw----    1 root     root        5,   2 Jan 13 05:52 ptmx

drwxr-xr-x    2 root     root             0 Jan  1  2007 pts

brw-rw----    1 root     root        1,   0 Jan 13 05:35 ram0

brw-rw----    1 root     root        1,   1 Jan 13 05:35 ram1

brw-rw----    1 root     root        1,  10 Jan 13 05:35 ram10

brw-rw----    1 root     root        1,  11 Jan 13 05:35 ram11

brw-rw----    1 root     root        1,  12 Jan 13 05:35 ram12

brw-rw----    1 root     root        1,  13 Jan 13 05:35 ram13

brw-rw----    1 root     root        1,  14 Jan 13 05:35 ram14

brw-rw----    1 root     root        1,  15 Jan 13 05:35 ram15

brw-rw----    1 root     root        1,   2 Jan 13 05:35 ram2

brw-rw----    1 root     root        1,   3 Jan 13 05:35 ram3

brw-rw----    1 root     root        1,   4 Jan 13 05:35 ram4

brw-rw----    1 root     root        1,   5 Jan 13 05:35 ram5

brw-rw----    1 root     root        1,   6 Jan 13 05:35 ram6

brw-rw----    1 root     root        1,   7 Jan 13 05:35 ram7

brw-rw----    1 root     root        1,   8 Jan 13 05:35 ram8

brw-rw----    1 root     root        1,   9 Jan 13 05:35 ram9

crw-rw----    1 root     root        1,   8 Jan 13 05:35 random

crw-rw----    1 root     root      254,   0 Jan 13 05:35 rtc0

lrwxrwxrwx    1 root     root             4 Jan 13 05:35 stderr -> fd/2

lrwxrwxrwx    1 root     root             4 Jan 13 05:35 stdin -> fd/0

lrwxrwxrwx    1 root     root             4 Jan 13 05:35 stdout -> fd/1

crw-rw----    1 root     root        5,   0 Jan 13 05:35 tty

crw-rw----    1 root     root      204,  64 Jan 13 05:35 ttyBF0

crw-rw----    1 root     root        1,   9 Jan 13 05:35 urandom

crw-rw----    1 root     root       10, 130 Jan 13 05:35 watchdog

crw-rw----    1 root     root        1,   5 Jan 13 05:35 zero

root:/dev>

however in:

root:/sys/devices/platform/i2c-bfin-twi.0> ls -la

drwxr-xr-x    3 root     root             0 Jan 13 06:04 .

drwxr-xr-x   17 root     root             0 Jan 13 05:35 ..

-r--r--r--    1 root     root          4096 Jan 13 06:05 modalias

drwxr-xr-x    2 root     root             0 Jan 13 06:05 power

lrwxrwxrwx    1 root     root             0 Jan 13 06:05 subsystem -> ../../../bus/platform

-rw-r--r--    1 root     root          4096 Jan 13 06:05 uevent

there is something pointing on i2c. But it doesn't seems to be complete.

You mentioned "i2c-bfin-twi driver". is that really necessary? I thought if "I2C device interface functionality" in the kernel works it is everything i need to run a twi interface.

thanks for your help

Ralph

You should enable i2c bfin twi driver.

You have two items chosen as "M", please use "Y" instead. for details of i2c dev please read Documentation/i2c/dev-interface in kernel source code.

Thanks Sonic,

after following Aaronwus advice to change M to Y in the kernel settings

(M = module, I expected to enable all child options ...??)

plus some recompilation trails I found out

Device Drivers  --->

      {*} I2C support  --->

     <*>   I2C device interface

     I2C Hardware Bus support  --->

         <*> Blackfin TWI I2C suppor

I didn't enable Blackfin TWI2C support as you mentioned in your last post. after that it works

some functions expect a link in the path /dev/i2c-0 similar to gpio interface

the entry however is under:

root:/sys/devices/platform/i2c-bfin-twi.0/i2c-0

anyway for me it's fine

thanks for your help

Ralph

The Hardware Bus support is for the actual physical I2C controller you want to use in your design, on blackfin platform it should be  either Blackfin TWI I2C support or GPIO-based, depending on your hardware.