[PATCH] PCI: use the MCFG table to properly access pci devices (i386)

Now that we have access to the whole MCFG table, let's properly use it
for all pci device accesses (as that's what it is there for, some boxes
don't put all the busses into one entry.)

If, for some reason, the table is incorrect, we fallback to the "old
style" of mmconfig accesses, namely, we just assume the first entry in
the table is the one for us, and blindly use it.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/i386/pci/mmconfig.c

@@ -22,10 +22,31 @@ static u32 mmcfg_last_accessed_device;
 /*
  * Functions for accessing PCI configuration space with MMCONFIG accesses
  */
+static u32 get_base_addr(unsigned int seg, int bus)
+{
+	int cfg_num = -1;
+	struct acpi_table_mcfg_config *cfg;
+
+	while (1) {
+		++cfg_num;
+		if (cfg_num >= pci_mmcfg_config_num) {
+			/* something bad is going on, no cfg table is found. */
+			/* so we fall back to the old way we used to do this */
+			/* and just rely on the first entry to be correct. */
+			return pci_mmcfg_config[0].base_address;
+		}
+		cfg = &pci_mmcfg_config[cfg_num];
+		if (cfg->pci_segment_group_number != seg)
+			continue;
+		if ((cfg->start_bus_number <= bus) &&
+		    (cfg->end_bus_number >= bus))
+			return cfg->base_address;
+	}
+}
 
-static inline void pci_exp_set_dev_base(int bus, int devfn)
+static inline void pci_exp_set_dev_base(unsigned int seg, int bus, int devfn)
 {
-	u32 dev_base = pci_mmcfg_config[0].base_address | (bus << 20) | (devfn << 12);
+	u32 dev_base = get_base_addr(seg, bus) | (bus << 20) | (devfn << 12);
 	if (dev_base != mmcfg_last_accessed_device) {
 		mmcfg_last_accessed_device = dev_base;
 		set_fixmap_nocache(FIX_PCIE_MCFG, dev_base);
@@ -42,7 +63,7 @@ static int pci_mmcfg_read(unsigned int seg, unsigned int bus,
 
 	spin_lock_irqsave(&pci_config_lock, flags);
 
-	pci_exp_set_dev_base(bus, devfn);
+	pci_exp_set_dev_base(seg, bus, devfn);
 
 	switch (len) {
 	case 1:
@@ -71,7 +92,7 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
 
 	spin_lock_irqsave(&pci_config_lock, flags);
 
-	pci_exp_set_dev_base(bus, devfn);
+	pci_exp_set_dev_base(seg, bus, devfn);
 
 	switch (len) {
 	case 1: