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Subject[PATCH v8 2/2] clocksource: timer-davinci: add support for clocksource
Date
From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Extend the davinci-timer driver to also register a clock source.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
drivers/clocksource/timer-davinci.c | 85 +++++++++++++++++++++++++++++
1 file changed, 85 insertions(+)

diff --git a/drivers/clocksource/timer-davinci.c b/drivers/clocksource/timer-davinci.c
index 246a5564495d..62745c962049 100644
--- a/drivers/clocksource/timer-davinci.c
+++ b/drivers/clocksource/timer-davinci.c
@@ -43,6 +43,8 @@
#define DAVINCI_TIMER_MIN_DELTA 0x01
#define DAVINCI_TIMER_MAX_DELTA 0xfffffffe

+#define DAVINCI_TIMER_CLKSRC_BITS 32
+
#define DAVINCI_TIMER_TGCR_DEFAULT \
(DAVINCI_TIMER_TIMMODE_32BIT_UNCHAINED | DAVINCI_TIMER_UNRESET)

@@ -52,6 +54,16 @@ struct davinci_clockevent {
unsigned int cmp_off;
};

+/*
+ * This must be globally accessible by davinci_timer_read_sched_clock(), so
+ * let's keep it here.
+ */
+static struct {
+ struct clocksource dev;
+ void __iomem *base;
+ unsigned int tim_off;
+} davinci_clocksource;
+
static struct davinci_clockevent *
to_davinci_clockevent(struct clock_event_device *clockevent)
{
@@ -166,6 +178,53 @@ static irqreturn_t davinci_timer_irq_timer(int irq, void *data)
return IRQ_HANDLED;
}

+static u64 notrace davinci_timer_read_sched_clock(void)
+{
+ return readl_relaxed(davinci_clocksource.base +
+ davinci_clocksource.tim_off);
+}
+
+static u64 davinci_clocksource_read(struct clocksource *dev)
+{
+ return davinci_timer_read_sched_clock();
+}
+
+/*
+ * Standard use-case: we're using tim12 for clockevent and tim34 for
+ * clocksource. The default is making the former run in oneshot mode
+ * and the latter in periodic mode.
+ */
+static void davinci_clocksource_init_tim34(void __iomem *base)
+{
+ int tcr;
+
+ tcr = DAVINCI_TIMER_ENAMODE_PERIODIC <<
+ DAVINCI_TIMER_ENAMODE_SHIFT_TIM34;
+ tcr |= DAVINCI_TIMER_ENAMODE_ONESHOT <<
+ DAVINCI_TIMER_ENAMODE_SHIFT_TIM12;
+
+ writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TIM34);
+ writel_relaxed(UINT_MAX, base + DAVINCI_TIMER_REG_PRD34);
+ writel_relaxed(tcr, base + DAVINCI_TIMER_REG_TCR);
+}
+
+/*
+ * Special use-case on da830: the DSP may use tim34. We're using tim12 for
+ * both clocksource and clockevent. We set tim12 to periodic and don't touch
+ * tim34.
+ */
+static void davinci_clocksource_init_tim12(void __iomem *base)
+{
+ unsigned int tcr;
+
+ tcr = DAVINCI_TIMER_ENAMODE_PERIODIC <<
+ DAVINCI_TIMER_ENAMODE_SHIFT_TIM12;
+
+ writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TIM12);
+ writel_relaxed(UINT_MAX, base + DAVINCI_TIMER_REG_PRD12);
+ writel_relaxed(tcr, base + DAVINCI_TIMER_REG_TCR);
+}
+
static void davinci_timer_init(void __iomem *base)
{
/* Set clock to internal mode and disable it. */
@@ -247,6 +306,32 @@ int __init davinci_timer_register(struct clk *clk,
DAVINCI_TIMER_MIN_DELTA,
DAVINCI_TIMER_MAX_DELTA);

+ davinci_clocksource.dev.rating = 300;
+ davinci_clocksource.dev.read = davinci_clocksource_read;
+ davinci_clocksource.dev.mask =
+ CLOCKSOURCE_MASK(DAVINCI_TIMER_CLKSRC_BITS);
+ davinci_clocksource.dev.flags = CLOCK_SOURCE_IS_CONTINUOUS;
+ davinci_clocksource.base = base;
+
+ if (timer_cfg->cmp_off) {
+ davinci_clocksource.dev.name = "tim12";
+ davinci_clocksource.tim_off = DAVINCI_TIMER_REG_TIM12;
+ davinci_clocksource_init_tim12(base);
+ } else {
+ davinci_clocksource.dev.name = "tim34";
+ davinci_clocksource.tim_off = DAVINCI_TIMER_REG_TIM34;
+ davinci_clocksource_init_tim34(base);
+ }
+
+ rv = clocksource_register_hz(&davinci_clocksource.dev, tick_rate);
+ if (rv) {
+ pr_err("Unable to register clocksource");
+ return rv;
+ }
+
+ sched_clock_register(davinci_timer_read_sched_clock,
+ DAVINCI_TIMER_CLKSRC_BITS, tick_rate);
+
return 0;
}

--
2.21.0
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