* [PATCH 2/4 v2] mach-integrator: clockevent supports oneshot mode
@ 2011-09-08 20:13 Linus Walleij
0 siblings, 0 replies; only message in thread
From: Linus Walleij @ 2011-09-08 20:13 UTC (permalink / raw)
To: linux-arm-kernel
The Integrator AP timer has no problem supporting oneshot
ticks with proper code, so let's do it so we can have
NOHZ configured in for this platform too.
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
ChangeLog v1->v2:
- Make sure that setting the periodic mode arms and fires a
periodic timer, and have the oneshot mode leave the timer
disabled until the .set_next_event occurs.
- Tested in both in explicit periodic and oneshot mode, by
removing the CLOCK_EVT_FEAT_ONESHOT and testing, and
removing CLOCK_EVT_FEAT_PERIODIC and testing. In periodic
mode I get ~6050 timer interrupts per minute, in
oneshot mode with NOHZ I get ~3066 timer interrups per
minute so it seems to be working.
---
arch/arm/mach-integrator/integrator_ap.c | 24 +++++++++++++++++++-----
1 files changed, 19 insertions(+), 5 deletions(-)
diff --git a/arch/arm/mach-integrator/integrator_ap.c b/arch/arm/mach-integrator/integrator_ap.c
index aa30ab6..e66a8bc 100644
--- a/arch/arm/mach-integrator/integrator_ap.c
+++ b/arch/arm/mach-integrator/integrator_ap.c
@@ -360,15 +360,29 @@ static void clkevt_set_mode(enum clock_event_mode mode, struct clock_event_devic
{
u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE;
- BUG_ON(mode == CLOCK_EVT_MODE_ONESHOT);
+ /* Disable timer */
+ writel(ctrl, clkevt_base + TIMER_CTRL);
- if (mode == CLOCK_EVT_MODE_PERIODIC) {
- writel(ctrl, clkevt_base + TIMER_CTRL);
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ /* Enable the timer and start the periodic tick */
writel(timer_reload, clkevt_base + TIMER_LOAD);
ctrl |= TIMER_CTRL_PERIODIC | TIMER_CTRL_ENABLE;
+ writel(ctrl, clkevt_base + TIMER_CTRL);
+ break;
+ case CLOCK_EVT_MODE_ONESHOT:
+ /* Leave the timer disabled, .set_next_event will enable it */
+ ctrl &= ~TIMER_CTRL_PERIODIC;
+ writel(ctrl, clkevt_base + TIMER_CTRL);
+ break;
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ case CLOCK_EVT_MODE_RESUME:
+ default:
+ /* Just leave in disabled state */
+ break;
}
- writel(ctrl, clkevt_base + TIMER_CTRL);
}
static int clkevt_set_next_event(unsigned long next, struct clock_event_device *evt)
@@ -385,7 +399,7 @@ static int clkevt_set_next_event(unsigned long next, struct clock_event_device *
static struct clock_event_device integrator_clockevent = {
.name = "timer1",
.shift = 34,
- .features = CLOCK_EVT_FEAT_PERIODIC,
+ .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
.set_mode = clkevt_set_mode,
.set_next_event = clkevt_set_next_event,
.rating = 300,
--
1.7.6
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