x86/PCI: Detect mmconfig on nVidia MCP55

Detect and enable memory-mapped PCI configuration space on the nVidia
MCP55 southbridge.  Tested against 2.6.27.4 on an Arista Networks
development board with one MCP55, Coreboot firmware, no ACPI.

Signed-off-by: Ed Swierk <eswierk@aristanetworks.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 64 insertions, 0 deletions

diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c
index 89bf9242c80a..d68dc1bb01b2 100644
--- a/arch/x86/pci/mmconfig-shared.c
+++ b/arch/x86/pci/mmconfig-shared.c
@@ -154,6 +154,68 @@ static const char __init *pci_mmcfg_amd_fam10h(void)
         return "AMD Family 10h NB";
 }
 
+static bool __initdata mcp55_checked;
+static const char __init *pci_mmcfg_nvidia_mcp55(void)
+{
+        int bus;
+        int mcp55_mmconf_found = 0;
+
+        static const u32 extcfg_regnum          = 0x90;
+        static const u32 extcfg_regsize         = 4;
+        static const u32 extcfg_enable_mask     = 1<<31;
+        static const u32 extcfg_start_mask      = 0xff<<16;
+        static const int extcfg_start_shift     = 16;
+        static const u32 extcfg_size_mask       = 0x3<<28;
+        static const int extcfg_size_shift      = 28;
+        static const int extcfg_sizebus[]       = {0x100, 0x80, 0x40, 0x20};
+        static const u32 extcfg_base_mask[]     = {0x7ff8, 0x7ffc, 0x7ffe, 0x7fff};
+        static const int extcfg_base_lshift     = 25;
+
+        /*
+         * do check if amd fam10h already took over
+         */
+        if (!acpi_disabled || pci_mmcfg_config_num || mcp55_checked)
+                return NULL;
+
+        mcp55_checked = true;
+        for (bus = 0; bus < 256; bus++) {
+                u64 base;
+                u32 l, extcfg;
+                u16 vendor, device;
+                int start, size_index, end;
+
+                raw_pci_ops->read(0, bus, PCI_DEVFN(0, 0), 0, 4, &l);
+                vendor = l & 0xffff;
+                device = (l >> 16) & 0xffff;
+
+                if (PCI_VENDOR_ID_NVIDIA != vendor || 0x0369 != device)
+                        continue;
+
+                raw_pci_ops->read(0, bus, PCI_DEVFN(0, 0), extcfg_regnum,
+                                  extcfg_regsize, &extcfg);
+
+                if (!(extcfg & extcfg_enable_mask))
+                        continue;
+
+                if (extend_mmcfg(1) == -1)
+                        continue;
+
+                size_index = (extcfg & extcfg_size_mask) >> extcfg_size_shift;
+                base = extcfg & extcfg_base_mask[size_index];
+                /* base could > 4G */
+                base <<= extcfg_base_lshift;
+                start = (extcfg & extcfg_start_mask) >> extcfg_start_shift;
+                end = start + extcfg_sizebus[size_index] - 1;
+                fill_one_mmcfg(base, 0, start, end);
+                mcp55_mmconf_found++;
+        }
+
+        if (!mcp55_mmconf_found)
+                return NULL;
+
+        return "nVidia MCP55";
+}
+
 struct pci_mmcfg_hostbridge_probe {
         u32 bus;
         u32 devfn;
@@ -171,6 +233,8 @@ static struct pci_mmcfg_hostbridge_probe pci_mmcfg_probes[] __initdata = {
           0x1200, pci_mmcfg_amd_fam10h },
         { 0xff, PCI_DEVFN(0, 0), PCI_VENDOR_ID_AMD,
           0x1200, pci_mmcfg_amd_fam10h },
+        { 0, PCI_DEVFN(0, 0), PCI_VENDOR_ID_NVIDIA,
+          0x0369, pci_mmcfg_nvidia_mcp55 },
 };
 
 static int __init pci_mmcfg_check_hostbridge(void)