regulator: palmas: Fix calculating selector in palmas_map_voltage_ldo

This patch fixes below issues when choosing selector:

1. Current code returns negative selector if min_uV < 900000 which is wrong.
   For example, it is possible to satisfy the request with selector = 1 if
   the requested min_uV is 850000.
2. Current code may select a voltage lower than requested min_uV.
   For example, if the requested min_uV is 945000, current code chooses
   selector = 1 which is lower than requested min_uV.
   DIV_ROUND_UP to avoid this case.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/regulator/palmas-regulator.c b/drivers/regulator/palmas-regulator.c
index 17d19fbbc490..0fcf3550f65d 100644
--- a/drivers/regulator/palmas-regulator.c
+++ b/drivers/regulator/palmas-regulator.c
@@ -486,9 +486,12 @@ static int palmas_map_voltage_ldo(struct regulator_dev *rdev,
 {
         int ret, voltage;
 
-        ret = ((min_uV - 900000) / 50000) + 1;
-        if (ret < 0)
-                return ret;
+        if (min_uV == 0)
+                return 0;
+
+        if (min_uV < 900000)
+                min_uV = 900000;
+        ret = DIV_ROUND_UP(min_uV - 900000, 50000) + 1;
 
         /* Map back into a voltage to verify we're still in bounds */
         voltage = palmas_list_voltage_ldo(rdev, ret);