Subject: [RFC v2 12/18] ARM: OMAP2+: timer: Add suspend-resume callbacks for clockevent device

From: [email-masked] (Jon Hunter)
Date: Thu, 17 Jan 2013 12:45:43 -0600

On 01/10/2013 10:37 PM, Bedia, Vaibhav wrote:
> On Tue, Jan 08, 2013 at 20:45:10, Shilimkar, Santosh wrote:
>> On Monday 31 December 2012 06:37 PM, Vaibhav Bedia wrote:
>>> The current OMAP timer code registers two timers -
>>> one as clocksource and one as clockevent.
>>> AM33XX has only one usable timer in the WKUP domain
>>> so one of the timers needs suspend-resume support
>>> to restore the configuration to pre-suspend state.
>>>
>>> commit adc78e6 (timekeeping: Add suspend and resume
>>> of clock event devices) introduced .suspend and .resume
>>> callbacks for clock event devices. Leverages these
>>> callbacks to have AM33XX clockevent timer which is
>>> in not in WKUP domain to behave properly across system
>>> suspend.
>>>
>>> Signed-off-by: Vaibhav Bedia <[email-masked]>
>>> Cc: Santosh Shilimkar <[email-masked]>
>>> Cc: Benoit Cousson <[email-masked]>
>>> Cc: Paul Walmsley <[email-masked]>
>>> Cc: Kevin Hilman <[email-masked]>
>>> Cc: Vaibhav Hiremath <[email-masked]>
>>> Cc: Jon Hunter <[email-masked]>
>>> ---
>>> v1->v2:
>>> 	Get rid of harcoded timer id.
>>> 	Note: since a platform device is not created for these timer
>>> 	instances and because there's very minimal change needed for
>>> 	restarting the timer a full blown context save and restore
>>> 	has been skipped.
>>>
>>>   arch/arm/mach-omap2/timer.c |   33 +++++++++++++++++++++++++++++++++
>>>   1 files changed, 33 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c
>>> index 691aa67..38f9cbc 100644
>>> --- a/arch/arm/mach-omap2/timer.c
>>> +++ b/arch/arm/mach-omap2/timer.c
>>> @@ -128,6 +128,36 @@ static void omap2_gp_timer_set_mode(enum clock_event_mode mode,
>>>   	}
>>>   }
>>>
>>> +static void omap_clkevt_suspend(struct clock_event_device *unused)
>>> +{
>>> +	char name[10];
>>> +	struct omap_hwmod *oh;
>>> +
>>> +	sprintf(name, "timer%d", clkev.id);
>>> +	oh = omap_hwmod_lookup(name);
>>> +	if (!oh)
>>> +		return;
>>> +
>>> +	__omap_dm_timer_stop(&clkev, 1, clkev.rate);
>>> +	omap_hwmod_idle(oh);
>>> +}
>>> +
>>> +static void omap_clkevt_resume(struct clock_event_device *unused)
>>> +{
>>> +	char name[10];
>>> +	struct omap_hwmod *oh;
>>> +
>>> +	sprintf(name, "timer%d", clkev.id);
>>> +	oh = omap_hwmod_lookup(name);
>>> +	if (!oh)
>>> +		return;
>>> +
>>> +	omap_hwmod_enable(oh);
>>> +	__omap_dm_timer_load_start(&clkev,
>>> +			OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR, 0, 1);
>>> +	__omap_dm_timer_int_enable(&clkev, OMAP_TIMER_INT_OVERFLOW);
>>> +}
>>> +
>> Am still bit uncomfortable with direct hwmod usage in the suspend/resmue
>> hooks.
>>
>> Jon, Any alternatives you can think of ?
>>
> 
> Jon,
> 
> Any suggestions here?

Sorry completed this missed this!

Unfortunately, I don't have any good suggestions here. However, I am
wondering if the suspend/resume handlers can just be calls to
omap_hwmod_idle/enable and we can remove these __omap_dm_timer_xxxx
calls (I don't think they are needed). Furthermore, my understanding is
this is only needed for AM335x (per the changelog), and so we should not
add suspend/resume handlers for all OMAP2+ based devices.

Cheers
Jon