[PATCH 1/4] clocksource/drivers/timer-tegra186: Fix support for multiple watchdog instances

[Kartik Rajput <kkartik@nvidia.com>]

Tegra SoCs support multiple watchdogs; currently only one (WDT0) is
used. When multiple watchdogs are registered, tegra186_wdt_enable()
overwrites the TKEIE(x) register, discarding any existing watchdog
interrupt enable bits. As a result, enabling one watchdog inadvertently
disables interrupts for the others.

Fix this by preserving the existing TKEIE(x) value and updating it
using a read-modify-write sequence.

Fixes: 42cee19a9f83 ("clocksource: Add Tegra186 timers support")
Cc: stable@vger.kernel.org
Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
---
 drivers/clocksource/timer-tegra186.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/timer-tegra186.c b/drivers/clocksource/timer-tegra186.c
index 355558893e5f..bfe16d2d5104 100644
--- a/drivers/clocksource/timer-tegra186.c
+++ b/drivers/clocksource/timer-tegra186.c
@@ -149,7 +149,8 @@ static void tegra186_wdt_enable(struct tegra186_wdt *wdt)
 	u32 value;
 
 	/* unmask hardware IRQ, this may have been lost across powergate */
-	value = TKEIE_WDT_MASK(wdt->index, 1);
+	value = readl(tegra->regs + TKEIE(wdt->tmr->hwirq));
+	value |= TKEIE_WDT_MASK(wdt->index, 1);
 	writel(value, tegra->regs + TKEIE(wdt->tmr->hwirq));
 
 	/* clear interrupt */
-- 
2.43.0