[PATCH] PCI: Ignore pre-set 64-bit BARs on 32-bit platforms

[pci] Ignore pre-set 64-bit BARs on 32-bit platforms

Currently, Linux always rejects a device which has a pre-set 64-bit
address on a 32-bit platform.  On systems which do not do PCI
initialization in firmware, this causes some devices which don't
correctly power up with all BARs zero to fail.

This patch makes the kernel automatically zero out such an address
(thus treating it as if it had not been set at all, meaning it will
assign an address if necessary).

I have done this only for devices, not bridges.  It seems potentially
hazardous to do for bridges.
Signed-off-by: NH. Peter Anvin <hpa@c2micro.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/pci/probe.c

@@ -180,25 +180,31 @@ static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom)
 		res->flags |= pci_calc_resource_flags(l);
 		if ((l & (PCI_BASE_ADDRESS_SPACE | PCI_BASE_ADDRESS_MEM_TYPE_MASK))
 		    == (PCI_BASE_ADDRESS_SPACE_MEMORY | PCI_BASE_ADDRESS_MEM_TYPE_64)) {
-			pci_read_config_dword(dev, reg+4, &l);
+			u32 szhi, lhi;
+			pci_read_config_dword(dev, reg+4, &lhi);
+			pci_write_config_dword(dev, reg+4, ~0);
+			pci_read_config_dword(dev, reg+4, &szhi);
+			pci_write_config_dword(dev, reg+4, lhi);
+			szhi = pci_size(lhi, szhi, 0xffffffff);
 			next++;
 #if BITS_PER_LONG == 64
-			res->start |= ((unsigned long) l) << 32;
+			res->start |= ((unsigned long) lhi) << 32;
 			res->end = res->start + sz;
-			pci_write_config_dword(dev, reg+4, ~0);
-			pci_read_config_dword(dev, reg+4, &sz);
-			pci_write_config_dword(dev, reg+4, l);
-			sz = pci_size(l, sz, 0xffffffff);
-			if (sz) {
+			if (szhi) {
 				/* This BAR needs > 4GB?  Wow. */
-				res->end |= (unsigned long)sz<<32;
+				res->end |= (unsigned long)szhi<<32;
 			}
 #else
-			if (l) {
-				printk(KERN_ERR "PCI: Unable to handle 64-bit address for device %s\n", pci_name(dev));
+			if (szhi) {
+				printk(KERN_ERR "PCI: Unable to handle 64-bit BAR for device %s\n", pci_name(dev));
 				res->start = 0;
 				res->flags = 0;
-				continue;
+			} else if (l) {
+				/* 64-bit wide address, treat as disabled */
+				pci_write_config_dword(dev, reg, l & ~(u32)PCI_BASE_ADDRESS_MEM_MASK);
+				pci_write_config_dword(dev, reg+4, 0);
+				res->start = 0;
+				res->end = sz;
 			}
 #endif
 		}