hwmon: (nct6775) Only report VID if supported and enabled

VID is not always enabled (NCT6775, NCT6776) or supported (NCT6779).

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

1 files changed, 24 insertions, 6 deletions

diff --git a/drivers/hwmon/nct6775.c b/drivers/hwmon/nct6775.c
index 6d5859718113..752fbd7efb32 100644
--- a/drivers/hwmon/nct6775.c
+++ b/drivers/hwmon/nct6775.c
@@ -3401,6 +3401,8 @@ static int nct6775_probe(struct platform_device *pdev)
         const u16 *reg_temp, *reg_temp_over, *reg_temp_hyst, *reg_temp_config;
         const u16 *reg_temp_alternate, *reg_temp_crit;
         int num_reg_temp;
+        bool have_vid = false;
+        u8 cr2a;
 
         res = platform_get_resource(pdev, IORESOURCE_IO, 0);
         if (!devm_request_region(&pdev->dev, res->start, IOREGION_LENGTH,
@@ -3769,17 +3771,31 @@ static int nct6775_probe(struct platform_device *pdev)
         /* Initialize the chip */
         nct6775_init_device(data);
 
-        data->vrm = vid_which_vrm();
         err = superio_enter(sio_data->sioreg);
         if (err)
                 return err;
 
+        cr2a = superio_inb(sio_data->sioreg, 0x2a);
+        switch (data->kind) {
+        case nct6775:
+                have_vid = (cr2a & 0x40);
+                break;
+        case nct6776:
+                have_vid = (cr2a & 0x60) == 0x40;
+                break;
+        case nct6779:
+                break;
+        }
+
         /*
          * Read VID value
          * We can get the VID input values directly at logical device D 0xe3.
          */
-        superio_select(sio_data->sioreg, NCT6775_LD_VID);
-        data->vid = superio_inb(sio_data->sioreg, 0xe3);
+        if (have_vid) {
+                superio_select(sio_data->sioreg, NCT6775_LD_VID);
+                data->vid = superio_inb(sio_data->sioreg, 0xe3);
+                data->vrm = vid_which_vrm();
+        }
 
         if (fan_debounce) {
                 u8 tmp;
@@ -3804,9 +3820,11 @@ static int nct6775_probe(struct platform_device *pdev)
 
         superio_exit(sio_data->sioreg);
 
-        err = device_create_file(dev, &dev_attr_cpu0_vid);
-        if (err)
-                return err;
+        if (have_vid) {
+                err = device_create_file(dev, &dev_attr_cpu0_vid);
+                if (err)
+                        return err;
+        }
 
         err = nct6775_check_fan_inputs(sio_data, data);
         if (err)