i.MX ProcessorsのトピックRe: Configure CCM_CCOSR register from kernel

Configure CCM_CCOSR register from kernel

damgot — Tue, 03 May 2016 14:04:15 GMT

Hello,

I'm using yocto to generate u-boot, kernel and rootfs for my IMX6S.

I'm using Linux 3.14.1.0.

What is the best way to configure CCM_CCOSR register from kernel ?

I would like to generate a 24.576 MHz for an audio codec but I don't find a proper way to configure CCM_CCOSR register.

Many thanks for your help.

Re: Configure CCM_CCOSR register from kernel

igorpadykov — Wed, 04 May 2016 01:04:22 GMT

Hi Damien

one can look at CLKO signal settings in clk-imx6q.c

linux-2.6-imx.git - Freescale i.MX Linux Tree

Best regards

igor

-----------------------------------------------------------------------------------------------------------------------

Note: If this post answers your question, please click the Correct Answer button. Thank you!

-----------------------------------------------------------------------------------------------------------------------

Re: Configure CCM_CCOSR register from kernel

damgot — Wed, 04 May 2016 08:37:31 GMT

Thanks for your answer.

But is there a way to generate a 24,576 MHz with the imx6 ? It looks not but I hope i'm wrong...

Best regards

Re: Configure CCM_CCOSR register from kernel

igorpadykov — Wed, 04 May 2016 11:19:18 GMT

one can try to configure some pll for example to 614.4MHz

then divide it by 25.

~igor

Re: Configure CCM_CCOSR register from kernel

damgot — Wed, 04 May 2016 12:54:42 GMT

Ok but where and how can I configure the PLL ? I'm not very familar with imx clock management and I don't find how to change clock in arch/arm/mach-imx/clk-imx6q.c.

It seems to be a list of clock with register address, shift and lenght but no value ?

Many thanks for your help.

Re: Configure CCM_CCOSR register from kernel

igorpadykov — Thu, 05 May 2016 01:59:54 GMT

please read sect.18.5.1.3 PLL reference clock i.MX6DQ Reference Manual

http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6DQRM.pdf

~igor

Re: Configure CCM_CCOSR register from kernel

damgot — Fri, 06 May 2016 07:35:25 GMT

Thanks for your answer but it's not help me.

I've already read this chapter and yes, it explain how to configure the PLL, and I know what to write in the PLL registers, but not where doing this in kernel drivers...

I can not find any documentation from freescale about this and the arch/arm/mach-imx/clk-imx6q.c are not very documented...

Re: Configure CCM_CCOSR register from kernel

aduskett — Mon, 24 Oct 2016 15:27:46 GMT

I too would like to know this. The clk-imx6q.c file is a mess and incredibly convoluted.

Re: Configure CCM_CCOSR register from kernel

deven_solanki — Wed, 16 Oct 2019 08:08:41 GMT

Hi,

I am also looking for the same. Any update on this ?

Could any one please give any example for the same.

Thanks in advance.