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hwmon: (ina2xx) Cast to s16 on shunt and current regs

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All devices supported by ina2xx are bidirectional and report the
measured shunt voltage and power values as a signed 16 bit, but the
current driver implementation caches all registers as u16, leading
to an incorrect sign extension when reporting to userspace in
ina2xx_get_value().

This patch fixes the problem by casting the signed registers to s16.
Tested on an INA219.

Signed-off-by: Fabio Baltieri <fabio.baltieri@gmail.com>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Fabio Baltieri 2014-06-08 22:06:24 +01:00 committed by Guenter Roeck
parent 5c02c392cd
commit c0214f9894
1 changed files with 4 additions and 3 deletions
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7
drivers/hwmon/ina2xx.c
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@ -148,7 +148,8 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 reg)
switch (reg) {
case INA2XX_SHUNT_VOLTAGE:
val = DIV_ROUND_CLOSEST(data->regs[reg],
/* signed register */
val = DIV_ROUND_CLOSEST((s16)data->regs[reg],
data->config->shunt_div);
break;
case INA2XX_BUS_VOLTAGE:
@ -160,8 +161,8 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 reg)
val = data->regs[reg] * data->config->power_lsb;
break;
case INA2XX_CURRENT:
/* LSB=1mA (selected). Is in mA */
val = data->regs[reg];
/* signed register, LSB=1mA (selected), in mA */
val = (s16)data->regs[reg];
break;
default:
/* programmer goofed */