[PATCH 5/9] clocksource: dw_apb_timer: quirk for variants without EOI register

["Heiko Stübner" <heiko@sntech.de>]

Some variants of the dw_apb_timer don't have an eoi register but instead expect a
one to be written to the int_status register at eoi time.

Signed-off-by: Ulrich Prinz <ulrich.prinz@googlemail.com>
---
 drivers/clocksource/dw_apb_timer.c |   10 +++++++++-
 include/linux/dw_apb_timer.h       |    5 +++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/dw_apb_timer.c b/drivers/clocksource/dw_apb_timer.c
index 5f80a30..23cd7c6 100644
--- a/drivers/clocksource/dw_apb_timer.c
+++ b/drivers/clocksource/dw_apb_timer.c
@@ -104,6 +104,11 @@ static void apbt_eoi(struct dw_apb_timer *timer)
 	apbt_readl(timer, timer->reg_eoi);
 }
 
+static void apbt_eoi_int_status(struct dw_apb_timer *timer)
+{
+	apbt_writel(timer, 1, timer->reg_int_status);
+}
+
 static irqreturn_t dw_apb_clockevent_irq(int irq, void *data)
 {
 	struct clock_event_device *evt = data;
@@ -286,7 +291,10 @@ dw_apb_clockevent_init(int cpu, const char *name, unsigned rating,
 					  IRQF_NOBALANCING |
 					  IRQF_DISABLED;
 
-	dw_ced->eoi = apbt_eoi;
+	if (quirks & APBTMR_QUIRK_NO_EOI)
+		dw_ced->eoi = apbt_eoi_int_status;
+	else
+		dw_ced->eoi = apbt_eoi;
 	err = setup_irq(irq, &dw_ced->irqaction);
 	if (err) {
 		pr_err("failed to request timer irq\n");
diff --git a/include/linux/dw_apb_timer.h b/include/linux/dw_apb_timer.h
index 80f6686..fbe4c6b 100644
--- a/include/linux/dw_apb_timer.h
+++ b/include/linux/dw_apb_timer.h
@@ -25,6 +25,11 @@
  */
 #define APBTMR_QUIRK_64BIT_COUNTER	BIT(0)
 
+/* The IP does not provide a end-of-interrupt register to clear pending
+ * interrupts, but requires to write a 1 to the interrupt-status register.
+ */
+#define APBTMR_QUIRK_NO_EOI		BIT(1)
+
 struct dw_apb_timer {
 	void __iomem				*base;
 	unsigned long				freq;
-- 
1.7.10.4