hwmon: (nct6775) Re-enable logical device mapping for NCT6791 during resume

After a suspend/resume cycle, the NCT6791 is back to its original BIOS
programming. In this state, HWMON IO access may be locked.
Re-enable it during resume.

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

1 files changed, 27 insertions, 11 deletions

diff --git a/drivers/hwmon/nct6775.c b/drivers/hwmon/nct6775.c
index cf811c1a1475..8686e966fa28 100644
--- a/drivers/hwmon/nct6775.c
+++ b/drivers/hwmon/nct6775.c
@@ -3936,6 +3936,18 @@ static int nct6775_probe(struct platform_device *pdev)
         return PTR_ERR_OR_ZERO(hwmon_dev);
 }
 
+static void nct6791_enable_io_mapping(int sioaddr)
+{
+        int val;
+
+        val = superio_inb(sioaddr, NCT6791_REG_HM_IO_SPACE_LOCK_ENABLE);
+        if (val & 0x10) {
+                pr_info("Enabling hardware monitor logical device mappings.\n");
+                superio_outb(sioaddr, NCT6791_REG_HM_IO_SPACE_LOCK_ENABLE,
+                             val & ~0x10);
+        }
+}
+
 #ifdef CONFIG_PM
 static int nct6775_suspend(struct device *dev)
 {
@@ -3955,11 +3967,20 @@ static int nct6775_suspend(struct device *dev)
 static int nct6775_resume(struct device *dev)
 {
         struct nct6775_data *data = dev_get_drvdata(dev);
-        int i, j;
+        int i, j, err = 0;
 
         mutex_lock(&data->update_lock);
         data->bank = 0xff;              /* Force initial bank selection */
 
+        if (data->kind == nct6791) {
+                err = superio_enter(data->sioreg);
+                if (err)
+                        goto abort;
+
+                nct6791_enable_io_mapping(data->sioreg);
+                superio_exit(data->sioreg);
+        }
+
         /* Restore limits */
         for (i = 0; i < data->in_num; i++) {
                 if (!(data->have_in & (1 << i)))
@@ -3996,11 +4017,12 @@ static int nct6775_resume(struct device *dev)
                 nct6775_write_value(data, NCT6775_REG_FANDIV2, data->fandiv2);
         }
 
+abort:
         /* Force re-reading all values */
         data->valid = false;
         mutex_unlock(&data->update_lock);
 
-        return 0;
+        return err;
 }
 
 static const struct dev_pm_ops nct6775_dev_pm_ops = {
@@ -4088,15 +4110,9 @@ static int __init nct6775_find(int sioaddr, struct nct6775_sio_data *sio_data)
                 pr_warn("Forcibly enabling Super-I/O. Sensor is probably unusable.\n");
                 superio_outb(sioaddr, SIO_REG_ENABLE, val | 0x01);
         }
-        if (sio_data->kind == nct6791) {
-                val = superio_inb(sioaddr, NCT6791_REG_HM_IO_SPACE_LOCK_ENABLE);
-                if (val & 0x10) {
-                        pr_info("Enabling hardware monitor logical device mappings.\n");
-                        superio_outb(sioaddr,
-                                     NCT6791_REG_HM_IO_SPACE_LOCK_ENABLE,
-                                     val & ~0x10);
-                }
-        }
+
+        if (sio_data->kind == nct6791)
+                nct6791_enable_io_mapping(sioaddr);
 
         superio_exit(sioaddr);
         pr_info("Found %s or compatible chip at %#x:%#x\n",