[PATCH 4.9 05/74] i2c: i801: store and restore the SLVCMD register at load and unload

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Benjamin Tissoires <benjamin.tissoi...@redhat.com>

commit 22e94bd6779e1140350c0792e85c79552ec43673 upstream.

Also do not override any other configuration in this register.

Signed-off-by: Benjamin Tissoires <benjamin.tissoi...@redhat.com>
Signed-off-by: Wolfram Sang <w...@the-dreams.de>
Cc: Jean Delvare <jdelv...@suse.de>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/i2c/busses/i2c-i801.c |   17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -243,6 +243,7 @@ struct i801_priv {
        struct i2c_adapter adapter;
        unsigned long smba;
        unsigned char original_hstcfg;
+       unsigned char original_slvcmd;
        struct pci_dev *pci_dev;
        unsigned int features;
 
@@ -962,13 +963,26 @@ static int i801_enable_host_notify(struc
        if (!priv->host_notify)
                return -ENOMEM;
 
-       outb_p(SMBSLVCMD_HST_NTFY_INTREN, SMBSLVCMD(priv));
+       priv->original_slvcmd = inb_p(SMBSLVCMD(priv));
+
+       if (!(SMBSLVCMD_HST_NTFY_INTREN & priv->original_slvcmd))
+               outb_p(SMBSLVCMD_HST_NTFY_INTREN | priv->original_slvcmd,
+                      SMBSLVCMD(priv));
+
        /* clear Host Notify bit to allow a new notification */
        outb_p(SMBSLVSTS_HST_NTFY_STS, SMBSLVSTS(priv));
 
        return 0;
 }
 
+static void i801_disable_host_notify(struct i801_priv *priv)
+{
+       if (!(priv->features & FEATURE_HOST_NOTIFY))
+               return;
+
+       outb_p(priv->original_slvcmd, SMBSLVCMD(priv));
+}
+
 static const struct i2c_algorithm smbus_algorithm = {
        .smbus_xfer     = i801_access,
        .functionality  = i801_func,
@@ -1666,6 +1680,7 @@ static void i801_remove(struct pci_dev *
        pm_runtime_forbid(&dev->dev);
        pm_runtime_get_noresume(&dev->dev);
 
+       i801_disable_host_notify(priv);
        i801_del_mux(priv);
        i2c_del_adapter(&priv->adapter);
        i801_acpi_remove(priv);