hwmon: (nct6775) Improve fan detection

Recent chips support multiple pins for fan speed inputs and fan control
outputs. Examine all of them to determine supported fan controls.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 37 insertions, 8 deletions

diff --git a/drivers/hwmon/nct6775.c b/drivers/hwmon/nct6775.c
index 318e0c5a34c8..4667691ca6a8 100644
--- a/drivers/hwmon/nct6775.c
+++ b/drivers/hwmon/nct6775.c
@@ -105,6 +105,7 @@ MODULE_PARM_DESC(fan_debounce, "Enable debouncing for fan RPM signal");
 #define NCT6775_LD_ACPI         0x0a
 #define NCT6775_LD_HWM          0x0b
 #define NCT6775_LD_VID          0x0d
+#define NCT6775_LD_12           0x12
 
 #define SIO_REG_LDSEL           0x07    /* Logical device select */
 #define SIO_REG_DEVID           0x20    /* Device ID (2 bytes) */
@@ -3392,6 +3393,8 @@ nct6775_check_fan_inputs(struct nct6775_data *data)
                 pwm5pin = false;
                 pwm6pin = false;
         } else {        /* NCT6779D, NCT6791D, NCT6792D, or NCT6793D */
+                int regval_1b, regval_2a, regval_eb;
+
                 regval = superio_inb(sioreg, 0x1c);
 
                 fan3pin = !(regval & BIT(5));
@@ -3402,17 +3405,43 @@ nct6775_check_fan_inputs(struct nct6775_data *data)
                 pwm4pin = !(regval & BIT(1));
                 pwm5pin = !(regval & BIT(2));
 
-                fan4min = fan4pin;
-
-                if (data->kind == nct6791 || data->kind == nct6792 ||
-                    data->kind == nct6793) {
-                        regval = superio_inb(sioreg, 0x2d);
-                        fan6pin = (regval & BIT(1));
-                        pwm6pin = (regval & BIT(0));
-                } else {        /* NCT6779D */
+                regval = superio_inb(sioreg, 0x2d);
+                switch (data->kind) {
+                case nct6791:
+                case nct6792:
+                        fan6pin = regval & BIT(1);
+                        pwm6pin = regval & BIT(0);
+                        break;
+                case nct6793:
+                        regval_1b = superio_inb(sioreg, 0x1b);
+                        regval_2a = superio_inb(sioreg, 0x2a);
+
+                        if (!pwm5pin)
+                                pwm5pin = regval & BIT(7);
+                        fan6pin = regval & BIT(1);
+                        pwm6pin = regval & BIT(0);
+                        if (!fan5pin)
+                                fan5pin = regval_1b & BIT(5);
+
+                        superio_select(sioreg, NCT6775_LD_12);
+                        regval_eb = superio_inb(sioreg, 0xeb);
+                        if (!fan5pin)
+                                fan5pin = regval_eb & BIT(5);
+                        if (!pwm5pin)
+                                pwm5pin = (regval_eb & BIT(4)) &&
+                                           !(regval_2a & BIT(0));
+                        if (!fan6pin)
+                                fan6pin = regval_eb & BIT(3);
+                        if (!pwm6pin)
+                                pwm6pin = regval_eb & BIT(2);
+                        break;
+                default:        /* NCT6779D */
                         fan6pin = false;
                         pwm6pin = false;
+                        break;
                 }
+
+                fan4min = fan4pin;
         }
 
         /* fan 1 and 2 (0x03) are always present */