MIPS: Cobalt: convert legacy port addresses to GT-64111 bus addresses

The GT-64111 PCI host bridge has no address translation mechanism, so
it can't generate legacy port accesses.  This quirk fixes legacy device
port resources to contain the bus addresses actually generated by the
GT-64111.

I think this is the approach Ben Herrenschmidt suggested long ago:
    http://marc.info/?l=linux-kernel&m=119733290624544&w=2

This allows us to remove the IORESOURCE_PCI_FIXED hack from
pcibios_fixup_device_resources(), which converts bus addresses to CPU
addresses.  IORESOURCE_PCI_FIXED denotes resources that can't be moved;
it has nothing to do with converting bus to CPU addresses.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Yoichi Yuasa <yuasa@linux-mips.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linux-mips@linux-mips.org
Tested-by: Yoichi Yuasa <yuasa@linux-mips.org>
Patchwork: http://patchwork.linux-mips.org/patch/998/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 61 insertions, 0 deletions

diff --git a/arch/mips/pci/fixup-cobalt.c b/arch/mips/pci/fixup-cobalt.c
index 9553b14002dd..acacd1407c63 100644
--- a/arch/mips/pci/fixup-cobalt.c
+++ b/arch/mips/pci/fixup-cobalt.c
@@ -51,6 +51,67 @@ static void qube_raq_galileo_early_fixup(struct pci_dev *dev)
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_MARVELL, PCI_DEVICE_ID_MARVELL_GT64111,
          qube_raq_galileo_early_fixup);
 
+static void __devinit cobalt_legacy_ide_resource_fixup(struct pci_dev *dev,
+                                                       struct resource *res)
+{
+        struct pci_controller *hose = (struct pci_controller *)dev->sysdata;
+        unsigned long offset = hose->io_offset;
+        struct resource orig = *res;
+
+        if (!(res->flags & IORESOURCE_IO) ||
+            !(res->flags & IORESOURCE_PCI_FIXED))
+                return;
+
+        res->start -= offset;
+        res->end -= offset;
+        dev_printk(KERN_DEBUG, &dev->dev, "converted legacy %pR to bus %pR\n",
+                   &orig, res);
+}
+
+static void __devinit cobalt_legacy_ide_fixup(struct pci_dev *dev)
+{
+        u32 class;
+        u8 progif;
+
+        /*
+         * If the IDE controller is in legacy mode, pci_setup_device() fills in
+         * the resources with the legacy addresses that normally appear on the
+         * PCI bus, just as if we had read them from a BAR.
+         *
+         * However, with the GT-64111, those legacy addresses, e.g., 0x1f0,
+         * will never appear on the PCI bus because it converts memory accesses
+         * in the PCI I/O region (which is never at address zero) into I/O port
+         * accesses with no address translation.
+         *
+         * For example, if GT_DEF_PCI0_IO_BASE is 0x10000000, a load or store
+         * to physical address 0x100001f0 will become a PCI access to I/O port
+         * 0x100001f0.  There's no way to generate an access to I/O port 0x1f0,
+         * but the VT82C586 IDE controller does respond at 0x100001f0 because
+         * it only decodes the low 24 bits of the address.
+         *
+         * When this quirk runs, the pci_dev resources should contain bus
+         * addresses, not Linux I/O port numbers, so convert legacy addresses
+         * like 0x1f0 to bus addresses like 0x100001f0.  Later, we'll convert
+         * them back with pcibios_fixup_bus() or pcibios_bus_to_resource().
+         */
+        class = dev->class >> 8;
+        if (class != PCI_CLASS_STORAGE_IDE)
+                return;
+
+        pci_read_config_byte(dev, PCI_CLASS_PROG, &progif);
+        if ((progif & 1) == 0) {
+                cobalt_legacy_ide_resource_fixup(dev, &dev->resource[0]);
+                cobalt_legacy_ide_resource_fixup(dev, &dev->resource[1]);
+        }
+        if ((progif & 4) == 0) {
+                cobalt_legacy_ide_resource_fixup(dev, &dev->resource[2]);
+                cobalt_legacy_ide_resource_fixup(dev, &dev->resource[3]);
+        }
+}
+
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C586_1,
+          cobalt_legacy_ide_fixup);
+
 static void qube_raq_via_bmIDE_fixup(struct pci_dev *dev)
 {
         unsigned short cfgword;