linux-kernel - [PATCH 1/2] clocksource/drivers/timer-tegra186: Avoid 64-bit divide operation

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Message-ID: <20250614175556.922159-1-linux@roeck-us.net>
Date: Sat, 14 Jun 2025 10:55:55 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: Thomas Gleixner <tglx@...utronix.de>,
	Thierry Reding <thierry.reding@...il.com>,
	Jonathan Hunter <jonathanh@...dia.com>,
	linux-kernel@...r.kernel.org,
	linux-tegra@...r.kernel.org,
	Guenter Roeck <linux@...ck-us.net>,
	Pohsun Su <pohsuns@...dia.com>,
	Robert Lin <robelin@...dia.com>
Subject: [PATCH 1/2] clocksource/drivers/timer-tegra186: Avoid 64-bit divide operation

Building the driver on xtensa fails with

tensa-linux-ld: drivers/clocksource/timer-tegra186.o:
	in function `tegra186_timer_remove':
timer-tegra186.c:(.text+0x350):
	undefined reference to `__udivdi3'

Avoid the problem by rearranging the offending code to avoid the 64-bit
divide operation.

Fixes: 28c842c8b0f5 ("clocksource/drivers/timer-tegra186: Add WDIOC_GETTIMELEFT support")
Cc: Pohsun Su <pohsuns@...dia.com>
Cc: Robert Lin <robelin@...dia.com>
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
 drivers/clocksource/timer-tegra186.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clocksource/timer-tegra186.c b/drivers/clocksource/timer-tegra186.c
index e5394f98a02e..7b506de65438 100644
--- a/drivers/clocksource/timer-tegra186.c
+++ b/drivers/clocksource/timer-tegra186.c
@@ -267,7 +267,7 @@ static unsigned int tegra186_wdt_get_timeleft(struct watchdog_device *wdd)
 	 * counter value to the time of the counter expirations that
 	 * remain.
 	 */
-	timeleft += (((u64)wdt->base.timeout * USEC_PER_SEC) / 5) * (4 - expiration);
+	timeleft += ((u64)wdt->base.timeout * (USEC_PER_SEC / 5)) * (4 - expiration);
 
 	/*
 	 * Convert the current counter value to seconds,
-- 
2.45.2