[PATCH] hwmon: w83792d fix unused fan pins

1. This patch add check for fan4,5,6,7 and do not create device file
   if their pins are not configured as fan.
2. Fix the issue that can not set fan divisor to 128.
3. Fix the index out of bounds bug in w83792d_detect function.

Signed-off-by: Yuan Mu <ymu@winbond.com.tw>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/hwmon/w83792d.c

@@ -193,6 +193,7 @@ static const u8 W83792D_REG_LEVELS[3][4] = {
 	  0xE2 }	/* (bit3-0) SmartFanII: Fan3 Level 3 */
 };
 
+#define W83792D_REG_GPIO_EN		0x1A
 #define W83792D_REG_CONFIG		0x40
 #define W83792D_REG_VID_FANDIV		0x47
 #define W83792D_REG_CHIPID		0x49
@@ -257,7 +258,7 @@ DIV_TO_REG(long val)
 {
 	int i;
 	val = SENSORS_LIMIT(val, 1, 128) >> 1;
-	for (i = 0; i < 6; i++) {
+	for (i = 0; i < 7; i++) {
 		if (val == 0)
 			break;
 		val >>= 1;
@@ -1282,8 +1283,8 @@ w83792d_detect(struct i2c_adapter *adapter, int address, int kind)
 	w83792d_init_client(new_client);
 
 	/* A few vars need to be filled upon startup */
-	for (i = 1; i <= 7; i++) {
-		data->fan_min[i - 1] = w83792d_read_value(new_client,
+	for (i = 0; i < 7; i++) {
+		data->fan_min[i] = w83792d_read_value(new_client,
 					W83792D_REG_FAN_MIN[i]);
 	}
 
@@ -1306,10 +1307,20 @@ w83792d_detect(struct i2c_adapter *adapter, int address, int kind)
 	device_create_file_fan(new_client, 1);
 	device_create_file_fan(new_client, 2);
 	device_create_file_fan(new_client, 3);
-	device_create_file_fan(new_client, 4);
-	device_create_file_fan(new_client, 5);
-	device_create_file_fan(new_client, 6);
-	device_create_file_fan(new_client, 7);
+
+	/* Read GPIO enable register to check if pins for fan 4,5 are used as
+	   GPIO */
+	val1 = w83792d_read_value(new_client, W83792D_REG_GPIO_EN);
+	if (!(val1 & 0x40))
+		device_create_file_fan(new_client, 4);
+	if (!(val1 & 0x20))
+		device_create_file_fan(new_client, 5);
+
+	val1 = w83792d_read_value(new_client, W83792D_REG_PIN);
+	if (val1 & 0x40)
+		device_create_file_fan(new_client, 6);
+	if (val1 & 0x04)
+		device_create_file_fan(new_client, 7);
 
 	device_create_file_temp1(new_client);		/* Temp1 */
 	device_create_file_temp_add(new_client, 2);	/* Temp2 */