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Subject[PATCH 3.15 067/122] hwmon: (ina2xx) Cast to s16 on shunt and current regs
Date
3.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Fabio Baltieri <fabio.baltieri@gmail.com>

commit c0214f98943b1fe43f7be61b7782b0c8f0836f28 upstream.

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>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/hwmon/ina2xx.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/hwmon/ina2xx.c
+++ b/drivers/hwmon/ina2xx.c
@@ -148,7 +148,8 @@ static int ina2xx_get_value(struct ina2x

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 ina2x
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 */



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