[PATCH v2 1/5] clocksource: mediatek: do not enable GPT_CLK_EVT when setup

[Yingjoe Chen <yingjoe.chen@mediatek.com>]

Spurious mtk timer interrupt is noticed at boot and cause kernel
crash. It seems if GPT is enabled, it will latch irq status even
when its IRQ is disabled. When irq is enabled afterward, we see
spurious interrupt.
Change init flow to only enable GPT_CLK_SRC at mtk_timer_init.

Acked-by: Matthias Brugger <matthias.bgg@gmail.com>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Yingjoe Chen <yingjoe.chen@mediatek.com>
---

Update to my patch [1], added __init as Daniel suggest. This is the
only patch that need to change in that series, so I only sent this one.

http://lists.infradead.org/pipermail/linux-mediatek/2015-July/001545.html

 drivers/clocksource/mtk_timer.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/clocksource/mtk_timer.c b/drivers/clocksource/mtk_timer.c
index 68ab423..2ba5b66 100644
--- a/drivers/clocksource/mtk_timer.c
+++ b/drivers/clocksource/mtk_timer.c
@@ -156,9 +156,11 @@ static void mtk_timer_global_reset(struct mtk_clock_event_device *evt)
 	writel(0x3f, evt->gpt_base + GPT_IRQ_ACK_REG);
 }
 
-static void
-mtk_timer_setup(struct mtk_clock_event_device *evt, u8 timer, u8 option)
+static void __init mtk_timer_setup(struct mtk_clock_event_device *evt,
+				   u8 timer, u8 option, bool enable)
 {
+	u32 val;
+
 	writel(TIMER_CTRL_CLEAR | TIMER_CTRL_DISABLE,
 		evt->gpt_base + TIMER_CTRL_REG(timer));
 
@@ -167,8 +169,10 @@ mtk_timer_setup(struct mtk_clock_event_device *evt, u8 timer, u8 option)
 
 	writel(0x0, evt->gpt_base + TIMER_CMP_REG(timer));
 
-	writel(TIMER_CTRL_OP(option) | TIMER_CTRL_ENABLE,
-			evt->gpt_base + TIMER_CTRL_REG(timer));
+	val = TIMER_CTRL_OP(option);
+	if (enable)
+		val |= TIMER_CTRL_ENABLE;
+	writel(val, evt->gpt_base + TIMER_CTRL_REG(timer));
 }
 
 static void mtk_timer_enable_irq(struct mtk_clock_event_device *evt, u8 timer)
@@ -235,12 +239,12 @@ static void __init mtk_timer_init(struct device_node *node)
 	evt->ticks_per_jiffy = DIV_ROUND_UP(rate, HZ);
 
 	/* Configure clock source */
-	mtk_timer_setup(evt, GPT_CLK_SRC, TIMER_CTRL_OP_FREERUN);
+	mtk_timer_setup(evt, GPT_CLK_SRC, TIMER_CTRL_OP_FREERUN, true);
 	clocksource_mmio_init(evt->gpt_base + TIMER_CNT_REG(GPT_CLK_SRC),
 			node->name, rate, 300, 32, clocksource_mmio_readl_up);
 
 	/* Configure clock event */
-	mtk_timer_setup(evt, GPT_CLK_EVT, TIMER_CTRL_OP_REPEAT);
+	mtk_timer_setup(evt, GPT_CLK_EVT, TIMER_CTRL_OP_REPEAT, false);
 	clockevents_config_and_register(&evt->dev, rate, 0x3,
 					0xffffffff);
 
-- 
1.8.1.1.dirty