[Precise SRU][Quantal] mei: add mei_quirk_probe function

[Zhao, Yingying]

One customer reported a bug that Ubuntu 12.04 will hang on the C600/X79 servers with SPS firmware.  This patch works around this issue.

The patch is included in upstream 3.6-rc3. Please consider to backport it to Ubuntu 12.04 and 12.10.

commit a2f6985332d2564e443d9d889ce70f39b3293d09
Author: Tomas Winkler <tomas.winkler at intel.com>
Date:   Mon Aug 6 15:23:55 2012 +0300

    mei: add mei_quirk_probe function

    The main purpose of this function is to exclude ME devices
    without support for MEI/HECI interface from binding

    Currently affected systems are C600/X79 based servers
    that expose PCI device even though it doesn't supported ME Interface.
    MEI driver accessing such nonfunctional device can corrupt
    the system.

    Signed-off-by: Tomas Winkler <tomas.winkler at intel.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>

diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
index 0923302..7422c76 100644
--- a/drivers/misc/mei/main.c
+++ b/drivers/misc/mei/main.c
@@ -925,6 +925,27 @@ static struct miscdevice  mei_misc_device = {
};

/**
+ * mei_quirk_probe - probe for devices that doesn't valid ME interface
+ * @pdev: PCI device structure
+ * @ent: entry into pci_device_table
+ *
+ * returns true if ME Interface is valid, false otherwise
+ */
+static bool __devinit mei_quirk_probe(struct pci_dev *pdev,
+                               const struct pci_device_id *ent)
+{
+       u32 reg;
+       if (ent->device == MEI_DEV_ID_PBG_1) {
+               pci_read_config_dword(pdev, 0x48, &reg);
+               /* make sure that bit 9 is up and bit 10 is down */
+               if ((reg & 0x600) == 0x200) {
+                       dev_info(&pdev->dev, "Device doesn't have valid ME Interface\n");
+                       return false;
+               }
+       }
+       return true;
+}
+/**
  * mei_probe - Device Initialization Routine
  *
  * @pdev: PCI device structure
@@ -939,6 +960,12 @@ static int __devinit mei_probe(struct pci_dev *pdev,
        int err;

        mutex_lock(&mei_mutex);
+
+       if (!mei_quirk_probe(pdev, ent)) {
+               err = -ENODEV;
+               goto end;
+       }
+
        if (mei_device) {
                err = -EEXIST;
                goto end;

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