Re: [PATCH 06/41] clocksource: exynos_mct: Migrate to new 'set-state' interface
From: Alexey Klimov
Date: Thu Jun 18 2015 - 12:38:30 EST
Hi Viresh,
(adding samsung list and Krzysztof to c/c)
Please don't forget to send patches to platform list and platform maintainers.
On Thu, Jun 18, 2015 at 1:54 PM, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
> Migrate exynos_mct driver to the new 'set-state' interface provided by
> clockevents core, the earlier 'set-mode' interface is marked obsolete
> now.
>
> This also enables us to implement callbacks for new states of clockevent
> devices, for example: ONESHOT_STOPPED.
>
> Cc: Kukjin Kim <kgene.kim@xxxxxxxxxxx>
> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> ---
> drivers/clocksource/exynos_mct.c | 85 +++++++++++++++++++---------------------
> 1 file changed, 40 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
> index 935b05936dbd..82e060cb7b95 100644
> --- a/drivers/clocksource/exynos_mct.c
> +++ b/drivers/clocksource/exynos_mct.c
> @@ -257,15 +257,14 @@ static void exynos4_mct_comp0_stop(void)
> exynos4_mct_write(0, EXYNOS4_MCT_G_INT_ENB);
> }
>
> -static void exynos4_mct_comp0_start(enum clock_event_mode mode,
> - unsigned long cycles)
> +static void exynos4_mct_comp0_start(bool periodic, unsigned long cycles)
> {
> unsigned int tcon;
> cycle_t comp_cycle;
>
> tcon = readl_relaxed(reg_base + EXYNOS4_MCT_G_TCON);
>
> - if (mode == CLOCK_EVT_MODE_PERIODIC) {
> + if (periodic) {
> tcon |= MCT_G_TCON_COMP0_AUTO_INC;
> exynos4_mct_write(cycles, EXYNOS4_MCT_G_COMP0_ADD_INCR);
> }
> @@ -283,38 +282,38 @@ static void exynos4_mct_comp0_start(enum clock_event_mode mode,
> static int exynos4_comp_set_next_event(unsigned long cycles,
> struct clock_event_device *evt)
> {
> - exynos4_mct_comp0_start(evt->mode, cycles);
> + exynos4_mct_comp0_start(false, cycles);
>
> return 0;
> }
>
> -static void exynos4_comp_set_mode(enum clock_event_mode mode,
> - struct clock_event_device *evt)
> +static int mct_set_state_shutdown(struct clock_event_device *evt)
> {
> - unsigned long cycles_per_jiffy;
> exynos4_mct_comp0_stop();
> + return 0;
> +}
>
> - switch (mode) {
> - case CLOCK_EVT_MODE_PERIODIC:
> - cycles_per_jiffy =
> - (((unsigned long long) NSEC_PER_SEC / HZ * evt->mult) >> evt->shift);
> - exynos4_mct_comp0_start(mode, cycles_per_jiffy);
> - break;
> +static int mct_set_state_periodic(struct clock_event_device *evt)
> +{
> + unsigned long cycles_per_jiffy;
>
> - case CLOCK_EVT_MODE_ONESHOT:
> - case CLOCK_EVT_MODE_UNUSED:
> - case CLOCK_EVT_MODE_SHUTDOWN:
> - case CLOCK_EVT_MODE_RESUME:
> - break;
> - }
> + cycles_per_jiffy = (((unsigned long long)NSEC_PER_SEC / HZ * evt->mult)
> + >> evt->shift);
> + exynos4_mct_comp0_stop();
> + exynos4_mct_comp0_start(true, cycles_per_jiffy);
> + return 0;
> }
>
> static struct clock_event_device mct_comp_device = {
> - .name = "mct-comp",
> - .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
> - .rating = 250,
> - .set_next_event = exynos4_comp_set_next_event,
> - .set_mode = exynos4_comp_set_mode,
> + .name = "mct-comp",
> + .features = CLOCK_EVT_FEAT_PERIODIC |
> + CLOCK_EVT_FEAT_ONESHOT,
> + .rating = 250,
> + .set_next_event = exynos4_comp_set_next_event,
> + .set_state_periodic = mct_set_state_periodic,
> + .set_state_shutdown = mct_set_state_shutdown,
> + .set_state_oneshot = mct_set_state_shutdown,
> + .tick_resume = mct_set_state_shutdown,
> };
>
> static irqreturn_t exynos4_mct_comp_isr(int irq, void *dev_id)
> @@ -390,39 +389,32 @@ static int exynos4_tick_set_next_event(unsigned long cycles,
> return 0;
> }
>
> -static inline void exynos4_tick_set_mode(enum clock_event_mode mode,
> - struct clock_event_device *evt)
> +static int set_state_shutdown(struct clock_event_device *evt)
> +{
> + exynos4_mct_tick_stop(this_cpu_ptr(&percpu_mct_tick));
Passed evt pointer isn't used and instead you're going to locate
percpu_mct_tick struct knowing current cpu number offset.
What do you think, since evt is embedded into percpu_mct_tick
structure then maybe it will be cheaper to calculate percpu_mct_tick
using container_of()?
struct mct_clock_event_device *mevt;
mevt = container_of(evt, struct mct_clock_event_device, evt);
> + return 0;
> +}
> +
> +static int set_state_periodic(struct clock_event_device *evt)
> {
> struct mct_clock_event_device *mevt = this_cpu_ptr(&percpu_mct_tick);
> unsigned long cycles_per_jiffy;
>
> + cycles_per_jiffy = (((unsigned long long)NSEC_PER_SEC / HZ * evt->mult)
> + >> evt->shift);
> exynos4_mct_tick_stop(mevt);
> -
> - switch (mode) {
> - case CLOCK_EVT_MODE_PERIODIC:
> - cycles_per_jiffy =
> - (((unsigned long long) NSEC_PER_SEC / HZ * evt->mult) >> evt->shift);
> - exynos4_mct_tick_start(cycles_per_jiffy, mevt);
> - break;
> -
> - case CLOCK_EVT_MODE_ONESHOT:
> - case CLOCK_EVT_MODE_UNUSED:
> - case CLOCK_EVT_MODE_SHUTDOWN:
> - case CLOCK_EVT_MODE_RESUME:
> - break;
> - }
> + exynos4_mct_tick_start(cycles_per_jiffy, mevt);
> + return 0;
> }
>
> static void exynos4_mct_tick_clear(struct mct_clock_event_device *mevt)
> {
> - struct clock_event_device *evt = &mevt->evt;
> -
> /*
> * This is for supporting oneshot mode.
> * Mct would generate interrupt periodically
> * without explicit stopping.
> */
> - if (evt->mode != CLOCK_EVT_MODE_PERIODIC)
> + if (!clockevent_state_periodic(&mevt->evt))
> exynos4_mct_tick_stop(mevt);
>
> /* Clear the MCT tick interrupt */
> @@ -455,7 +447,10 @@ static int exynos4_local_timer_setup(struct clock_event_device *evt)
> evt->name = mevt->name;
> evt->cpumask = cpumask_of(cpu);
> evt->set_next_event = exynos4_tick_set_next_event;
> - evt->set_mode = exynos4_tick_set_mode;
> + evt->set_state_periodic = set_state_periodic;
> + evt->set_state_shutdown = set_state_shutdown;
> + evt->set_state_oneshot = set_state_shutdown;
> + evt->tick_resume = set_state_shutdown;
Do i correctly understand that during massive hot-plug cpu events (i
guess that will lead to CPU_STARING notification) on power management
this *_timer_setup() function will be called?
And here code performs setting of rather constant values and copying.
You're going to increase number of such strange assignments.
Well, just lazy-thinking. Can we do something like this:
for_each_possible_cpu(cpu) {
exynos4_local_timer_setup_prepare(&per_cpu(percpu_mct_tick,
cpu).evt, cpu);
}
somewhere in exynos_mct init functions and assign most of these values
for each evt structure?
And make *_timer_setup() function lighter moving some code to
prepare/init functions.
If it makes any sense i can take a look and try to prepare patch.
> evt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
> evt->rating = 450;
>
> @@ -482,7 +477,7 @@ static int exynos4_local_timer_setup(struct clock_event_device *evt)
>
> static void exynos4_local_timer_stop(struct clock_event_device *evt)
> {
> - evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt);
> + evt->set_state_shutdown(evt);
> if (mct_int_type == MCT_INT_SPI)
> free_irq(evt->irq, this_cpu_ptr(&percpu_mct_tick));
> else
> --
Do you need testers? I can test it on odroid-xu3.
Can't find in emails similar patch for ARM arch timer. Any plans about
it? Or if it's already converted to 'set-state' then could you please
share a link?
Thanks and best regards,
Alexey Klimov
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/