[PATCH] hwmon:max6697: Make sure the OVERT mask is set correctly

[Chu Lin <linchuyuan@google.com>]

Per the datasheet for max6697, OVERT mask and ALERT mask is different.
For example, the 7th bit of OVERT is the local channel but for alert
mask, the 6th bit is the local channel. Therefore, we can't apply the
same mask for both reg. In addition to that, max6697 driver is suppose
to be compatibale with different models. I mannually went over all the
listed chip and made sure all the chip type has the same layout.

Testing;
    mask value of 0x9 should map to 0x44 for ALERT and 0x84 for OVERT.
I used iotool to read the reg value back to verify. I only tested this
change on max6581

Reference:
https://datasheets.maximintegrated.com/en/ds/MAX6581.pdf
https://datasheets.maximintegrated.com/en/ds/MAX6697.pdf
https://datasheets.maximintegrated.com/en/ds/MAX6699.pdf

Signed-off-by: Chu Lin <linchuyuan@google.com>
---
 drivers/hwmon/max6697.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/max6697.c b/drivers/hwmon/max6697.c
index 743752a2467a..64122eb38060 100644
--- a/drivers/hwmon/max6697.c
+++ b/drivers/hwmon/max6697.c
@@ -38,8 +38,9 @@ static const u8 MAX6697_REG_CRIT[] = {
  * Map device tree / platform data register bit map to chip bit map.
  * Applies to alert register and over-temperature register.
  */
-#define MAX6697_MAP_BITS(reg)	((((reg) & 0x7e) >> 1) | \
+#define MAX6697_ALERT_MAP_BITS(reg)	((((reg) & 0x7e) >> 1) | \
 				 (((reg) & 0x01) << 6) | ((reg) & 0x80))
+#define MAX6697_OVERT_MAP_BITS(reg) (((reg) >> 1) | (((reg) & 0x01) << 7))
 
 #define MAX6697_REG_STAT(n)		(0x44 + (n))
 
@@ -562,12 +563,12 @@ static int max6697_init_chip(struct max6697_data *data,
 		return ret;
 
 	ret = i2c_smbus_write_byte_data(client, MAX6697_REG_ALERT_MASK,
-					MAX6697_MAP_BITS(pdata->alert_mask));
+				MAX6697_ALERT_MAP_BITS(pdata->alert_mask));
 	if (ret < 0)
 		return ret;
 
 	ret = i2c_smbus_write_byte_data(client, MAX6697_REG_OVERT_MASK,
-				MAX6697_MAP_BITS(pdata->over_temperature_mask));
+			MAX6697_OVERT_MAP_BITS(pdata->over_temperature_mask));
 	if (ret < 0)
 		return ret;
 
-- 
2.27.0.111.gc72c7da667-goog