ARM: footbridge: add one-shot mode for DC21285 timer

Add a one-shot mode for the DC21285 timer.  This allows us to use the
NO_HZ modes on this platform.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 20 insertions, 2 deletions

diff --git a/arch/arm/mach-footbridge/dc21285-timer.c b/arch/arm/mach-footbridge/dc21285-timer.c
index 785e4199f9cd..2babdbcaa691 100644
--- a/arch/arm/mach-footbridge/dc21285-timer.c
+++ b/arch/arm/mach-footbridge/dc21285-timer.c
@@ -47,6 +47,16 @@ static struct clocksource cksrc_dc21285 = {
         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
+static int ckevt_dc21285_set_next_event(unsigned long delta,
+        struct clock_event_device *c)
+{
+        *CSR_TIMER1_CLR = 0;
+        *CSR_TIMER1_LOAD = delta;
+        *CSR_TIMER1_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_DIV16;
+
+        return 0;
+}
+
 static void ckevt_dc21285_set_mode(enum clock_event_mode mode,
         struct clock_event_device *c)
 {
@@ -59,7 +69,9 @@ static void ckevt_dc21285_set_mode(enum clock_event_mode mode,
                                    TIMER_CNTL_DIV16;
                 break;
 
-        default:
+        case CLOCK_EVT_MODE_ONESHOT:
+        case CLOCK_EVT_MODE_UNUSED:
+        case CLOCK_EVT_MODE_SHUTDOWN:
                 *CSR_TIMER1_CNTL = 0;
                 break;
         }
@@ -67,9 +79,11 @@ static void ckevt_dc21285_set_mode(enum clock_event_mode mode,
 
 static struct clock_event_device ckevt_dc21285 = {
         .name           = "dc21285_timer1",
-        .features       = CLOCK_EVT_FEAT_PERIODIC,
+        .features       = CLOCK_EVT_FEAT_PERIODIC |
+                          CLOCK_EVT_FEAT_ONESHOT,
         .rating         = 200,
         .irq            = IRQ_TIMER1,
+        .set_next_event = ckevt_dc21285_set_next_event,
         .set_mode       = ckevt_dc21285_set_mode,
 };
 
@@ -79,6 +93,10 @@ static irqreturn_t timer1_interrupt(int irq, void *dev_id)
 
         *CSR_TIMER1_CLR = 0;
 
+        /* Stop the timer if in one-shot mode */
+        if (ce->mode == CLOCK_EVT_MODE_ONESHOT)
+                *CSR_TIMER1_CNTL = 0;
+
         ce->event_handler(ce);
 
         return IRQ_HANDLED;