PCI: Separate pci_bus_read_dev_vendor_id from pci_scan_device

We can reuse it for pciehp probing.

-v2: according to Kenji, fix crs timeout checking, and export the function
     for later use when pciehp is compiled as a module.
Suggested-by: NMatthew Wilcox <matthew@wil.cx>
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/pci.h

@@ -207,6 +207,8 @@ enum pci_bar_type {
 	pci_bar_mem64,		/* A 64-bit memory BAR */
 };
 
+bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *pl,
+				int crs_timeout);
 extern int pci_setup_device(struct pci_dev *dev);
 extern int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 				struct resource *res, unsigned int reg);

drivers/pci/probe.c

@@ -1118,40 +1118,54 @@ struct pci_dev *alloc_pci_dev(void)
 }
 EXPORT_SYMBOL(alloc_pci_dev);
 
-/*
- * Read the config data for a PCI device, sanity-check it
- * and fill in the dev structure...
- */
-static struct pci_dev *pci_scan_device(struct pci_bus *bus, int devfn)
+bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
+				 int crs_timeout)
 {
-	struct pci_dev *dev;
-	u32 l;
 	int delay = 1;
 
-	if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, &l))
-		return NULL;
+	if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
+		return false;
 
 	/* some broken boards return 0 or ~0 if a slot is empty: */
-	if (l == 0xffffffff || l == 0x00000000 ||
-	    l == 0x0000ffff || l == 0xffff0000)
-		return NULL;
+	if (*l == 0xffffffff || *l == 0x00000000 ||
+	    *l == 0x0000ffff || *l == 0xffff0000)
+		return false;
 
 	/* Configuration request Retry Status */
-	while (l == 0xffff0001) {
+	while (*l == 0xffff0001) {
+		if (!crs_timeout)
+			return false;
+
 		msleep(delay);
 		delay *= 2;
-		if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, &l))
-			return NULL;
+		if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
+			return false;
 		/* Card hasn't responded in 60 seconds?  Must be stuck. */
-		if (delay > 60 * 1000) {
+		if (delay > crs_timeout) {
 			printk(KERN_WARNING "pci %04x:%02x:%02x.%d: not "
 					"responding\n", pci_domain_nr(bus),
 					bus->number, PCI_SLOT(devfn),
 					PCI_FUNC(devfn));
-			return NULL;
+			return false;
 		}
 	}
 
+	return true;
+}
+EXPORT_SYMBOL(pci_bus_read_dev_vendor_id);
+
+/*
+ * Read the config data for a PCI device, sanity-check it
+ * and fill in the dev structure...
+ */
+static struct pci_dev *pci_scan_device(struct pci_bus *bus, int devfn)
+{
+	struct pci_dev *dev;
+	u32 l;
+
+	if (!pci_bus_read_dev_vendor_id(bus, devfn, &l, 60*1000))
+		return NULL;
+
 	dev = alloc_pci_dev();
 	if (!dev)
 		return NULL;