hwmon: (nct6775) Enable auxiliary fan monitoring on ASRock Z77 Pro4-M

Auxiliary fan monitoring is not enabled on ASRock Z77 Pro4-M
with BIOS version 2.00 if booted in UEFI Ultra-FastBoot mode.

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

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/hwmon/nct6775.c b/drivers/hwmon/nct6775.c
index 0445a52379e7..4fcb48103299 100644
--- a/drivers/hwmon/nct6775.c
+++ b/drivers/hwmon/nct6775.c
@@ -57,6 +57,7 @@
 #include <linux/err.h>
 #include <linux/mutex.h>
 #include <linux/acpi.h>
+#include <linux/dmi.h>
 #include <linux/io.h>
 #include "lm75.h"
 
@@ -3199,6 +3200,26 @@ nct6775_check_fan_inputs(struct nct6775_data *data)
                 pwm6pin = false;
         } else if (data->kind == nct6776) {
                 bool gpok = superio_inb(sioreg, 0x27) & 0x80;
+                const char *board_vendor, *board_name;
+
+                board_vendor = dmi_get_system_info(DMI_BOARD_VENDOR);
+                board_name = dmi_get_system_info(DMI_BOARD_NAME);
+
+                if (board_name && board_vendor &&
+                    !strcmp(board_vendor, "ASRock")) {
+                        /*
+                         * Auxiliary fan monitoring is not enabled on ASRock
+                         * Z77 Pro4-M if booted in UEFI Ultra-FastBoot mode.
+                         * Observed with BIOS version 2.00.
+                         */
+                        if (!strcmp(board_name, "Z77 Pro4-M")) {
+                                if ((data->sio_reg_enable & 0xe0) != 0xe0) {
+                                        data->sio_reg_enable |= 0xe0;
+                                        superio_outb(sioreg, SIO_REG_ENABLE,
+                                                     data->sio_reg_enable);
+                                }
+                        }
+                }
 
                 if (data->sio_reg_enable & 0x80)
                         fan3pin = gpok;