clocksource/drivers/stm32: Add oneshot mode

[linux.git] / drivers / clocksource / timer-stm32.c

diff --git a/drivers/clocksource/timer-stm32.c b/drivers/clocksource/timer-stm32.c
index 928ac281f937a8cac7811df9376d40912fed0728..882037f1d8d6e14e314a7fdb813ae6451413ee88 100644 (file)
--- a/drivers/clocksource/timer-stm32.c
+++ b/drivers/clocksource/timer-stm32.c
@@ -24,14 +24,18 @@
 #define TIM_DIER       0x0c
 #define TIM_SR         0x10
 #define TIM_EGR                0x14
+#define TIM_CNT                0x24
 #define TIM_PSC                0x28
 #define TIM_ARR                0x2c
+#define TIM_CCR1       0x34
 
 #define TIM_CR1_CEN    BIT(0)
+#define TIM_CR1_UDIS   BIT(1)
 #define TIM_CR1_OPM    BIT(3)
 #define TIM_CR1_ARPE   BIT(7)
 
 #define TIM_DIER_UIE   BIT(0)
+#define TIM_DIER_CC1IE BIT(1)
 
 #define TIM_SR_UIF     BIT(0)
 
@@ -40,33 +44,57 @@
 #define TIM_PSC_MAX    USHRT_MAX
 #define TIM_PSC_CLKRATE        10000
 
+static void stm32_clock_event_disable(struct timer_of *to)
+{
+       writel_relaxed(0, timer_of_base(to) + TIM_DIER);
+}
+
+static void stm32_clock_event_enable(struct timer_of *to)
+{
+       writel_relaxed(TIM_CR1_UDIS | TIM_CR1_CEN, timer_of_base(to) + TIM_CR1);
+}
+
 static int stm32_clock_event_shutdown(struct clock_event_device *clkevt)
 {
        struct timer_of *to = to_timer_of(clkevt);
 
-       writel_relaxed(0, timer_of_base(to) + TIM_CR1);
+       stm32_clock_event_disable(to);
 
        return 0;
 }
 
-static int stm32_clock_event_set_periodic(struct clock_event_device *clkevt)
+static int stm32_clock_event_set_next_event(unsigned long evt,
+                                           struct clock_event_device *clkevt)
 {
        struct timer_of *to = to_timer_of(clkevt);
+       unsigned long now, next;
+
+       next = readl_relaxed(timer_of_base(to) + TIM_CNT) + evt;
+       writel_relaxed(next, timer_of_base(to) + TIM_CCR1);
+       now = readl_relaxed(timer_of_base(to) + TIM_CNT);
+
+       if ((next - now) > evt)
+               return -ETIME;
 
-       writel_relaxed(timer_of_period(to), timer_of_base(to) + TIM_ARR);
-       writel_relaxed(TIM_CR1_ARPE | TIM_CR1_CEN, timer_of_base(to) + TIM_CR1);
+       writel_relaxed(TIM_DIER_CC1IE, timer_of_base(to) + TIM_DIER);
 
        return 0;
 }
 
-static int stm32_clock_event_set_next_event(unsigned long evt,
-                                           struct clock_event_device *clkevt)
+static int stm32_clock_event_set_periodic(struct clock_event_device *clkevt)
+{
+       struct timer_of *to = to_timer_of(clkevt);
+
+       stm32_clock_event_enable(to);
+
+       return stm32_clock_event_set_next_event(timer_of_period(to), clkevt);
+}
+
+static int stm32_clock_event_set_oneshot(struct clock_event_device *clkevt)
 {
        struct timer_of *to = to_timer_of(clkevt);
 
-       writel_relaxed(evt, timer_of_base(to) + TIM_ARR);
-       writel_relaxed(TIM_CR1_ARPE | TIM_CR1_OPM | TIM_CR1_CEN,
-                      timer_of_base(to) + TIM_CR1);
+       stm32_clock_event_enable(to);
 
        return 0;
 }
@@ -78,6 +106,11 @@ static irqreturn_t stm32_clock_event_handler(int irq, void *dev_id)
 
        writel_relaxed(0, timer_of_base(to) + TIM_SR);
 
+       if (clockevent_state_periodic(clkevt))
+               stm32_clock_event_set_periodic(clkevt);
+       else
+               stm32_clock_event_shutdown(clkevt);
+
        clkevt->event_handler(clkevt);
 
        return IRQ_HANDLED;
@@ -108,9 +141,10 @@ static void __init stm32_clockevent_init(struct timer_of *to)
 
        to->clkevt.name = to->np->full_name;
        to->clkevt.features = CLOCK_EVT_FEAT_PERIODIC;
+       to->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
        to->clkevt.set_state_shutdown = stm32_clock_event_shutdown;
        to->clkevt.set_state_periodic = stm32_clock_event_set_periodic;
-       to->clkevt.set_state_oneshot = stm32_clock_event_shutdown;
+       to->clkevt.set_state_oneshot = stm32_clock_event_set_oneshot;
        to->clkevt.tick_resume = stm32_clock_event_shutdown;
        to->clkevt.set_next_event = stm32_clock_event_set_next_event;
 
@@ -129,12 +163,10 @@ static void __init stm32_clockevent_init(struct timer_of *to)
                prescaler = prescaler < TIM_PSC_MAX ? prescaler : TIM_PSC_MAX;
                to->clkevt.rating = 100;
        }
-       writel_relaxed(0, timer_of_base(to) + TIM_ARR);
 
        writel_relaxed(prescaler - 1, timer_of_base(to) + TIM_PSC);
        writel_relaxed(TIM_EGR_UG, timer_of_base(to) + TIM_EGR);
        writel_relaxed(0, timer_of_base(to) + TIM_SR);
-       writel_relaxed(TIM_DIER_UIE, timer_of_base(to) + TIM_DIER);
 
        /* Adjust rate and period given the prescaler value */
        to->of_clk.rate = DIV_ROUND_CLOSEST(to->of_clk.rate, prescaler);