AM335x device drivers

deepak ramegowda

Expert 1465 points

Team

I am new bee to device driver!

I have a beagle bone black

I have downloaded the source code of linux 4.1.15

My task is to understand the I2C and serial driver for beagle bone!

As i know only few things on device driver i want to make sure i2c and serial works on my board.

I want to know where could I find the source code driver for am335x device driver and serial device driver for am335x driver so that i can understand the code and can learn the frame work.

As I have downloaded the source code i am able to find the files of i2c for other soc but not for am335x

Example :i have i2c-bcm-kona.c i2c-bcm2835.c but not able to find the file that corresponds to am335x for beagle bone!

My intention is to see and check how implementation is done and analyse the driver!

Kindly let me know what could be the approach as i have already gone through the documentation folder of i2c and there frame work i need to quickly get into coding and test the driver by analysing!

Need help on finding and let me know the suitable approach to do this and where to start for driver development!

Thank you

Deepak R

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

The software team have been notified. They will respond here.

0 deepak ramegowda over 9 years ago in reply to Biser Gatchev-XID

Expert 1465 points

Thank you!waiting for software teams help!!!!!!!

0 Yordan Kovachev over 9 years ago

TI__Guru**** 161600 points

Hi Deepak,

The first thing you need to do is add the i2c you want to use in the dts file, you can take a reference from the implementation of i2c1 or i2c2 in arch/arm/boot/dts/am335x-bone-common.dtsi.

Now the actual SoC specific i2c driver is located in drivers/i2c/busses/i2c-omap.c.

From the filesystem you could use the created /dev/i2c-x entries to test the interface.

Best Regards,
Yordan

0 deepak ramegowda over 9 years ago in reply to Yordan Kovachev

Expert 1465 points

Hi
Yordan
Thanks for your reply!
but my beagle bone is AM335X
Does it mean omap_i2c.c covers the drivers for am335x also as they are from same family of OMAPL137??????
I could quickly find the following segment in code
Hope this actually shows the supported soc i2c-omap.c

static const struct of_device_id omap_i2c_of_match[] = {
{
.compatible = "ti,omap4-i2c",
.data = &omap4_pdata,
},
{
.compatible = "ti,omap3-i2c",
.data = &omap3_pdata,
},
{
.compatible = "ti,omap2430-i2c",
.data = &omap2430_pdata,
},
{
.compatible = "ti,omap2420-i2c",
.data = &omap2420_pdata,
},
{ },
};

Thank you
Deepak R

0 Yordan Kovachev over 9 years ago in reply to deepak ramegowda

TI__Guru**** 161600 points

Hi,

Does it mean omap_i2c.c covers the drivers for am335x also as they are from same family of OMAPL137??????

Yes, omap_i2c.c is the correct driver for am335x devices. No they are not from the same family as OMAPL137.... As far as I know OMAPL137 does not support later versions of the linux kernel.

Best Regards,
Yordan

0 deepak ramegowda over 9 years ago in reply to Yordan Kovachev

Expert 1465 points

Hi
Yordan,

Thanks for your help!
Then what driver code is used for omapl137 device for i2c!
Deepak R

0 Yordan Kovachev over 9 years ago in reply to deepak ramegowda

TI__Guru**** 161600 points

Hi,

It's i2c-davinci.c

Best Regards,
Yordan

0 deepak ramegowda over 9 years ago in reply to Yordan Kovachev

Expert 1465 points

Thanks yordan!

0 deepak ramegowda over 9 years ago in reply to deepak ramegowda

Expert 1465 points

but how are these segregated ...how to know the corresponding drivers for the soc ?is it by looking manually to drivers???

0 Yordan Kovachev over 9 years ago in reply to deepak ramegowda

TI__Guru**** 161600 points

Hi Deepak,

how to know the corresponding drivers for the soc ?is it by looking manually to drivers???

For later kernels like the one you use 4.1.15, you can open the dtsi file, which is included in the .dts. For am335x devices this is am33xx.dtsi, and check any i2c node:
i2c1: i2c@4802a000 {
compatible = "ti,omap4-i2c";
#address-cells = <1>;
#size-cells = <0>;
ti,hwmods = "i2c2";
reg = <0x4802a000 0x1000>;
interrupts = <71>;
status = "disabled";
};

You can see the string: compatible = "ti,omap4-i2c";. After that in the linux console you navigate to the linux folder:
cd ~/ti-processor-sdk-linux-am335x-evm-03.01.00.06/board-support/linux-4.4.19+gitAUTOINC+db0b54cdad-gdb0b54cdad/
and execute:
git grep "ti,omap4-i2c"
In the result you'll see the driver that is compatible with that dts node, something like:
drivers/i2c/busses/i2c-omap.c: .compatible = "ti,omap4-i2c",

Hope this helps.

Best Regards,
Yordan

0 deepak ramegowda over 9 years ago in reply to Yordan Kovachev

Expert 1465 points

Hi
Yordan
My doubt is like consider
beagle bone(am355x)--->omap_i2c.c
omapl137--->davinci_i2c.c
How do you map that based on soc for the first time!
Thank you
Deepak R

0 deepak ramegowda over 9 years ago in reply to Yordan Kovachev

Expert 1465 points

Thanks for the support yordan!

Processors

Processors forum

AM335x device drivers