[POWERPC] Fixup skipping of PowerMac PCI<->PCI bridge "closed" resources

Apple firmware has a strange way to "close" bridge resources by setting
them to some bogus values that overlap RAM (strangely, I haven't seen it
conflicting with DMA so far...).  This explicitely closes them to avoid
problems.  Previously, they would be closed as a consequence of failing
to be allocated, but this makes it more explicit, and thus the log
message is more explicit too.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index b6d4767e4e27..1037b3a093ee 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -776,6 +776,7 @@ DECLARE_PCI_FIXUP_HEADER(PCI_ANY_ID, PCI_ANY_ID, pcibios_fixup_resources);
 
 static void __devinit __pcibios_fixup_bus(struct pci_bus *bus)
 {
+        struct pci_controller *hose = pci_bus_to_host(bus);
         struct pci_dev *dev = bus->self;
 
         pr_debug("PCI: Fixup bus %d (%s)\n", bus->number, dev ? pci_name(dev) : "PHB");
@@ -793,6 +794,27 @@ static void __devinit __pcibios_fixup_bus(struct pci_bus *bus)
                         if (!res->flags || bus->self->transparent)
                                 continue;
 
+                        /* On PowerMac, Apple leaves bridge windows open over
+                         * an inaccessible region of memory space (0...fffff)
+                         * which is somewhat bogus, but that's what they think
+                         * means disabled...
+                         *
+                         * We clear those to force them to be reallocated later
+                         *
+                         * We detect such regions by the fact that the base is
+                         * equal to the pci_mem_offset of the host bridge and
+                         * their size is smaller than 1M.
+                         */
+                        if (res->start == hose->pci_mem_offset &&
+                            res->end < 0x100000) {
+                                printk(KERN_INFO
+                                       "PCI: Closing bogus Apple Firmware"
+                                       " region %d on bus 0x%02x\n",
+                                       i, bus->number);
+                                res->flags = 0;
+                                continue;
+                        }
+
                         pr_debug("PCI:%s Bus rsrc %d %016llx-%016llx [%x] fixup...\n",
                                  pci_name(dev), i,
                                  (unsigned long long)res->start,\