1 files changed, 27 insertions, 3 deletions

diff --git a/drivers/hwmon/smsc47m1.c b/drivers/hwmon/smsc47m1.c
index 92cca512b38e..9ca97818bd4b 100644
--- a/drivers/hwmon/smsc47m1.c
+++ b/drivers/hwmon/smsc47m1.c
@@ -136,6 +136,7 @@ struct smsc47m1_data {
 
 struct smsc47m1_sio_data {
         enum chips type;
+        u8 activate;            /* Remember initial device state */
 };
 
 
@@ -468,17 +469,38 @@ static int __init smsc47m1_find(unsigned short *addr,
         superio_select();
         *addr = (superio_inb(SUPERIO_REG_BASE) << 8)
               |  superio_inb(SUPERIO_REG_BASE + 1);
-        val = superio_inb(SUPERIO_REG_ACT);
-        if (*addr == 0 || (val & 0x01) == 0) {
-                pr_info(DRVNAME ": Device is disabled, will not use\n");
+        if (*addr == 0) {
+                pr_info(DRVNAME ": Device address not set, will not use\n");
                 superio_exit();
                 return -ENODEV;
         }
 
+        /* Enable only if address is set (needed at least on the
+         * Compaq Presario S4000NX) */
+        sio_data->activate = superio_inb(SUPERIO_REG_ACT);
+        if ((sio_data->activate & 0x01) == 0) {
+                pr_info(DRVNAME ": Enabling device\n");
+                superio_outb(SUPERIO_REG_ACT, sio_data->activate | 0x01);
+        }
+
         superio_exit();
         return 0;
 }
 
+/* Restore device to its initial state */
+static void __init smsc47m1_restore(const struct smsc47m1_sio_data *sio_data)
+{
+        if ((sio_data->activate & 0x01) == 0) {
+                superio_enter();
+                superio_select();
+
+                pr_info(DRVNAME ": Disabling device\n");
+                superio_outb(SUPERIO_REG_ACT, sio_data->activate);
+
+                superio_exit();
+        }
+}
+
 #define CHECK           1
 #define REQUEST         2
 #define RELEASE         3
@@ -856,6 +878,7 @@ static int __init sm_smsc47m1_init(void)
 
 exit_device:
         platform_device_unregister(pdev);
+        smsc47m1_restore(&sio_data);
 exit:
         return err;
 }
@@ -863,6 +886,7 @@ exit:
 static void __exit sm_smsc47m1_exit(void)
 {
         platform_driver_unregister(&smsc47m1_driver);
+        smsc47m1_restore(pdev->dev.platform_data);
         platform_device_unregister(pdev);
 }