mei: me: add kdoc for mei_me_fw_type_nm()

Add kdoc for mei_me_fw_type_nm() function.
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Link: https://lore.kernel.org/r/20200619165121.2145330-4-tomas.winkler@intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mei/hw-me.c

@@ -1353,11 +1353,24 @@ static const struct mei_hw_ops mei_me_hw_ops = {
 	.read = mei_me_read_slots
 };
 
+/**
+ * mei_me_fw_type_nm() - check for nm sku
+ *
+ * Read ME FW Status register to check for the Node Manager (NM) Firmware.
+ * The NM FW is only signaled in PCI function 0.
+ * __Note__: Deprecated by PCH8 and newer.
+ *
+ * @pdev: pci device
+ *
+ * Return: true in case of NM firmware
+ */
 static bool mei_me_fw_type_nm(const struct pci_dev *pdev)
 {
 	u32 reg;
+	unsigned int devfn;
 
-	pci_read_config_dword(pdev, PCI_CFG_HFS_2, &reg);
+	devfn = PCI_DEVFN(PCI_SLOT(pdev->devfn), 0);
+	pci_bus_read_config_dword(pdev->bus, devfn, PCI_CFG_HFS_2, &reg);
 	trace_mei_pci_cfg_read(&pdev->dev, "PCI_CFG_HFS_2", PCI_CFG_HFS_2, reg);
 	/* make sure that bit 9 (NM) is up and bit 10 (DM) is down */
 	return (reg & 0x600) == 0x200;