ks8695_gettimeoffset

[Dick Hollenbeck]

On 01/03/2011 01:55 PM, avictor.za at gmail.com wrote:
> hi,
>
>> Is it possible at all to implement clocksource/clockevents for KS8695? As Dick and "Register Description" already said you cannot read the time register, so clocksource->read cannot be implemented to return ticks elapsed. Or do I see it wrong?
> I'm pretty sure I tested this when I originally submitted the KS8685
> processor support (May 2007), and the timer registers are readable.
> I would of tested with a userspace program that sat in a tight loop
> calling gettimeofday().
>
>
> Regards,
>   Andrew Victor
>

Thanks Andrew.  Can you explain how this is supposed to be a duration, even
if one of these two registers was a readable down counter?

 elapsed = __raw_readl(KS8695_TMR_VA + KS8695_T1TC) + __raw_readl(KS8695_TMR_VA + KS8695_T1PD);


Which of the two is a down counter, and why would it be added to one that is not, or is?

While you are thinking about that, I have a userspace test program that can peek at the two registers using a memory mapped region pointer, and it will tell us if the value is changing over time.


The register description PDF document says the values *are readable*, but that description does not specifically say what is being read back, the preload value or the dynamically down counting value.

Doc Extraction:

TOUT1PC aka T1PD offset 0xE40C

This field specifies the duration that the TOUT1 pin is High in each
timeout period. Writing zero to this register may cuase unpredictalbe
behavior.

TOUT1TC aka T1TC offset 0xE404

This field specifies the duration that the TOUT1 pin is Low in each
timeout period. Writing zero to this register may cuase unpredictalbe
behavior.


Thanks,

Dick