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

[Jon Hunter <jon-hunter@ti.com>]

On 12/31/2012 07:07 AM, 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 <vaibhav.bedia@ti.com>
> Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
> Cc: Benoit Cousson <b-cousson@ti.com>
> Cc: Paul Walmsley <paul@pwsan.com>
> Cc: Kevin Hilman <khilman@deeprootsystems.com>
> Cc: Vaibhav Hiremath <hvaibhav@ti.com>
> Cc: Jon Hunter <jon-hunter@ti.com>
> ---
> 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);

I am not sure you need to call __omap_dm_timer_stop() here. This should
have already been called as timekeeping_suspend() will call
omap2_gp_timer_set_mode() to shutdown the timer.

> +	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);

Similarly here, I am not sure these __omap_dm_timer_xxxx calls are needed.

> +}
> +
>  static struct clock_event_device clockevent_gpt = {
>  	.name		= "gp_timer",
>  	.features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
> @@ -135,6 +165,8 @@ static struct clock_event_device clockevent_gpt = {
>  	.rating		= 300,
>  	.set_next_event	= omap2_gp_timer_set_next_event,
>  	.set_mode	= omap2_gp_timer_set_mode,
> +	.suspend	= omap_clkevt_suspend,
> +	.resume		= omap_clkevt_resume,

AFAIK, this is only applicable for AM335x devices and so should not be
added for all.

>  };
>  
>  static struct property device_disabled = {
> @@ -323,6 +355,7 @@ static void __init omap2_gp_clockevent_init(int gptimer_id,
>  	int res;
>  
>  	clkev.errata = omap_dm_timer_get_errata();
> +	clkev.id = gptimer_id;

We should not use gptimer_id anymore. This will go away once the
migration to dev-tree is completed. You may be better off storing the
oh_name in the clock_event_device name field and passing to the
suspend/resume handlers.

Cheers
Jon