From: Dien Pham <redacted>

As description for DIV_ROUND_CLOSEST in file include/linux/kernel.h.
  "Result is undefined for negative divisors if the dividend variable
   type is unsigned and for negative dividends if the divisor variable
   type is unsigned."

In current code, the FIXPT_DIV uses DIV_ROUND_CLOSEST but has not
checked sign of divisor before using. It makes undefined temperature
value in case the value is negative.

This patch fixes to satisfy DIV_ROUND_CLOSEST description
and fix bug too. Note that the name "reg" is not good because it should
be the same type as rcar_gen3_thermal_read(). So, rename it with "ctemp".

Signed-off-by: Van Do <redacted>
Signed-off-by: Dien Pham <redacted>
[shimoda: minor fixes, add Fixes tag]
Fixes: 564e73d283af ("thermal: rcar_gen3_thermal: Add R-Car Gen3 thermal driver")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
---
 Changes from v1:
 - Use int instead of long.
 - Rename "reg" with "ctemp".
 https://patchwork.kernel.org/patch/11593051/

 drivers/thermal/rcar_gen3_thermal.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/thermal/rcar_gen3_thermal.c b/drivers/thermal/rcar_gen3_thermal.c
index 58fe7c1..49ea330 100644
--- a/drivers/thermal/rcar_gen3_thermal.c
+++ b/drivers/thermal/rcar_gen3_thermal.c

@@ -167,16 +167,16 @@ static int rcar_gen3_thermal_get_temp(void *devdata, int *temp)
 {
 	struct rcar_gen3_thermal_tsc *tsc = devdata;
 	int mcelsius, val;
-	u32 reg;
+	int ctemp;
 
 	/* Read register and convert to mili Celsius */
-	reg = rcar_gen3_thermal_read(tsc, REG_GEN3_TEMP) & CTEMP_MASK;
+	ctemp = rcar_gen3_thermal_read(tsc, REG_GEN3_TEMP) & CTEMP_MASK;
 
-	if (reg <= thcode[tsc->id][1])
-		val = FIXPT_DIV(FIXPT_INT(reg) - tsc->coef.b1,
+	if (ctemp <= thcode[tsc->id][1])
+		val = FIXPT_DIV(FIXPT_INT(ctemp) - tsc->coef.b1,
 				tsc->coef.a1);
 	else
-		val = FIXPT_DIV(FIXPT_INT(reg) - tsc->coef.b2,
+		val = FIXPT_DIV(FIXPT_INT(ctemp) - tsc->coef.b2,
 				tsc->coef.a2);
 	mcelsius = FIXPT_TO_MCELSIUS(val);
 

-- 
2.7.4