RE: Help Regarding I2C Driver...

Uma Kanta
2009-03-24T05:36:51Z

Hi Daniel,
Thanks for your reply..

> > This is Uma Kanta, seeking some help regarding the
> > I2C driver development on ARM Linux 2.6.19 platform.
>
> This version is ancient, you should consider updating to something
> more recent.

Yaa, this version is very old, but as currently I have to develop for
this version for our project so I have to try developing in this
version itself.

>
> > I referred the second part of i2C driver articles in Linux Journal
> > by Greg Kroah. As well as the book Essential Linux Device Drivers.
> > I have to make I2C driver for a RTC (DS1340) and a camera module
> > (Omnivision OVM7670).
> > I could be able to make a chip driver. Unfortunately I was unable to

> > insert the core driver "i2c_core" internally. So I inserted the
> > i2c_core.ko and my own driver i2c_test.ko.
> > Now both drivers are getting inserted fine but the problem exists
is:
> > In my init I am adding my i2c driver structure by using
> > "i2c_add_driver()", and my i2c driver structure named
> > "i2c_test_driver", whose declaration is as
> > follows:
> >
> > struct i2c_driver i2c_test_driver = {
> > .driver = {
> > .name = "i2c_test",
> > },
> > .id = I2C_DRIVERID_OVCAMCHIP, /*
> > OmniVision CMOS image sens. *//* defined in
> > include/linux/i2c-id.h */
> > .attach_adapter =
> > i2c_test_attach_adapter,
> > .detach_client = i2c_test_detach_client, };
>
> attach_adapter and friends are legacy callbacks, you should not use
> them in new drivers. Did you read Documentation/i2c/writing-clients?

Can you please tell me what may be the alternative option for
"attach_adapter"
Field of i2c_driver. Also I read the documentation in
Documentation/i2c/writing-clients of Linux 2.6.19. Also I made my code
in the same way as the examples in drivers/i2c/chips/. But I am not
having th effect.

>
> > So here "list_for_each(item,&adapters)" returns FALSE for me. So my
> > attach adapter function, "i2c_test_attach_adapter()" is not getting
called.
>
> Probing should be done by setting i2c_board_info from your board
> support code - also described in Documentation/i2c/writing-clients.

Actually in Linux 2.6.19 I feel that there is no provisions for
i2c_board_info, as non of the existing chip drivers such as eeprom,
RTCs don't have any i2c_board_info structure in the file
arch\arm\mach-at91rm9200\board-ek.c.
Also in this version the function, "at91_add_device_i2c()" does not
accept arguments whereas in the advanced versions it takes two
arguments such as object of structure i2c_board_info and its size.
So what may be the alternative of i2c_board_info in case of Linux
2.6.19?
Is it possible to work with I2C in Linux 2.6.19???
>
> > So I searched where the entry "adapters" is getting a tail added in
> > the function "i2c_add_adapter()" So the function "i2c_add_adapter
> > ()" will be called by any client driver(as mentioned in comment...).
> > I tried by all "*.ko" files in KERN_SRC/drivers/i2c/algos/ but no
effect.
> > So now to get the full functional I2C chip driver do I need to write

> > a client driver for it?
>
> You're digging too much through the core code. It works well for
> others, so debugging this part is not the first thing you should
> consider. Best thing is probably to grab an existing driver and see
> how it does the job.
Actually I wanted to know where I was lagging. But now as previously I
mentioned I am not able to get the I2C working for my driver.
One more thing as I am doing for ARM platform,I wanted to know the
significance of the bus driver i2c-at91.
Do I need to take care of that to create my chip driver?

Thanks for the patience...

With Regards,
Uma Kanta Patro