hwmon: (it87) Enhance validation for fan4 and fan5

Several of the chips supported by this driver have a configuration
register to enable fan4 and fan5. Use those registers to determine
if fan4 and fan5 tachometers are supported.

Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
index f40d81a0a9fc..5adb269918fb 100644
--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -2415,6 +2415,29 @@ static int __init it87_find(int sioaddr, unsigned short *address,
 
                 superio_select(sioaddr, GPIO);
 
+                /* Check for fan4, fan5 */
+                if (has_five_fans(config)) {
+                        reg = superio_inb(sioaddr, IT87_SIO_GPIO2_REG);
+                        switch (sio_data->type) {
+                        case it8718:
+                                if (reg & BIT(5))
+                                        sio_data->skip_fan |= BIT(3);
+                                if (reg & BIT(4))
+                                        sio_data->skip_fan |= BIT(4);
+                                break;
+                        case it8720:
+                        case it8721:
+                        case it8728:
+                                if (!(reg & BIT(5)))
+                                        sio_data->skip_fan |= BIT(3);
+                                if (!(reg & BIT(4)))
+                                        sio_data->skip_fan |= BIT(4);
+                                break;
+                        default:
+                                break;
+                        }
+                }
+
                 reg = superio_inb(sioaddr, IT87_SIO_GPIO3_REG);
                 if (!sio_data->skip_vid) {
                         /* We need at least 4 VID pins */