linux-kernel - [PATCH] power: supply: use ktime_divns() to avoid 64-bit division

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Message-Id: <20251015075957.8F40620057@lion.mk-sys.cz>
Date: Wed, 15 Oct 2025 09:56:31 +0200
From: Michal Kubecek <mkubecek@...e.cz>
To: Sebastian Reichel <sre@...nel.org>,
    linux-pm@...r.kernel.org
Cc: Hans de Goede <hansg@...nel.org>,
    Linus Walleij <linus.walleij@...aro.org>,
    linux-kernel@...r.kernel.org
Subject: [PATCH] power: supply: use ktime_divns() to avoid 64-bit division

The build of intel_dc_ti_battery module on i386 (32-bit) fails with

ERROR: modpost: "__udivdi3" [drivers/power/supply/intel_dc_ti_battery.ko]

This is caused by 64-bit division of ktime values by NSEC_PER_USEC. Use
ktime_divns() helper which handles the division correctly on 32-bit
architectures.

Fixes: 8c5795fe5527 ("power: supply: Add new Intel Dollar Cove TI battery driver")
Signed-off-by: Michal Kubecek <mkubecek@...e.cz>
---
 drivers/power/supply/intel_dc_ti_battery.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/power/supply/intel_dc_ti_battery.c b/drivers/power/supply/intel_dc_ti_battery.c
index 56b0c92e9d28..c26209ef9577 100644
--- a/drivers/power/supply/intel_dc_ti_battery.c
+++ b/drivers/power/supply/intel_dc_ti_battery.c
@@ -141,7 +141,7 @@ static int dc_ti_battery_get_voltage_and_current_now(struct power_supply *psy, i
 	if (ret)
 		goto out_err;
 
-	cnt_start_usec = ktime_get_ns() / NSEC_PER_USEC;
+	cnt_start_usec = ktime_divns(ktime_get_ns(), NSEC_PER_USEC);
 
 	/* Read Vbat, convert IIO mV to power-supply ųV */
 	ret = iio_read_channel_processed_scale(chip->vbat_channel, volt, 1000);
@@ -149,7 +149,7 @@ static int dc_ti_battery_get_voltage_and_current_now(struct power_supply *psy, i
 		goto out_err;
 
 	/* Sleep at least 3 sample-times + slack to get 3+ CC samples */
-	now_usec = ktime_get_ns() / NSEC_PER_USEC;
+	now_usec = ktime_divns(ktime_get_ns(), NSEC_PER_USEC);
 	sleep_usec = 3 * SMPL_INTVL_US + SLEEP_SLACK_US - (now_usec - cnt_start_usec);
 	if (sleep_usec > 0 && sleep_usec < 1000000)
 		usleep_range(sleep_usec, sleep_usec + SLEEP_SLACK_US);
-- 
2.51.0