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hwmon: adm1275: Detect coefficient overflow

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Sashiko detected potential coefficient overflow if large shunt resistor
is used. When going unnoticed it can cause "drastically incorrect
telemetry scaling factors" as Sashiko put it.

I am not convinced such "drastically incorrect telemetry scaling
factors" could have gone unnoticed, so I suspect such large shunt
resistors aren't really used. Well, it shouldn't hurt to detect the
error and abort the probe before Really Wrong current / power -values
are reported to user by the hwmon.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/d9e3320dbd62e094ff89598cb3aac5b5e716f9e7.1782458224.git.mazziesaccount@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Matti Vaittinen 2026-06-26 10:23:58 +03:00 committed by Guenter Roeck
parent 553f951781
commit 72a6910103
1 changed files with 14 additions and 4 deletions
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18
drivers/hwmon/pmbus/adm1275.c
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@ -839,15 +839,25 @@ static int adm1275_probe(struct i2c_client *client)
info->R[PSC_VOLTAGE_OUT] = coefficients[voindex].R;
}
if (cindex >= 0) {
u32 m;
/* Scale current with sense resistor value */
info->m[PSC_CURRENT_OUT] =
coefficients[cindex].m * shunt / 1000;
if (unlikely(check_mul_overflow(coefficients[cindex].m, shunt, &m))) {
dev_err(&client->dev, "Current coefficient overflow\n");
return -EOVERFLOW;
}
info->m[PSC_CURRENT_OUT] = m / 1000;
info->b[PSC_CURRENT_OUT] = coefficients[cindex].b;
info->R[PSC_CURRENT_OUT] = coefficients[cindex].R;
}
if (pindex >= 0) {
info->m[PSC_POWER] =
coefficients[pindex].m * shunt / 1000;
u32 m;
if (unlikely(check_mul_overflow(coefficients[pindex].m, shunt, &m))) {
dev_err(&client->dev, "Power coefficient overflow\n");
return -EOVERFLOW;
}
info->m[PSC_POWER] = m / 1000;
info->b[PSC_POWER] = coefficients[pindex].b;
info->R[PSC_POWER] = coefficients[pindex].R;
}