Re: [PATCH] Detect mmconfig on nVidia MCP55

[Ed Swierk <eswierk@aristanetworks.com>]

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>

---

I've tried to incorporate the code style feedback from Ingo.  I'm not
sure whether this correctly handles boards with more than one MCP55, or
with an AMD 10h--Yinghai?

Index: linux-2.6.27.4/arch/x86/pci/mmconfig-shared.c
===================================================================
--- linux-2.6.27.4.orig/arch/x86/pci/mmconfig-shared.c
+++ linux-2.6.27.4/arch/x86/pci/mmconfig-shared.c
@@ -166,6 +166,36 @@ static const char __init *pci_mmcfg_amd_
 	return "AMD Family 10h NB";
 }
 
+static const char __init *pci_mmcfg_nvidia_mcp55(void)
+{
+	u32 extcfg;
+	u64 base;
+	int end;
+	static const u32 extcfg_regnum =      0x90;
+	static const u32 extcfg_regsize =     4;
+	static const u32 extcfg_enable_mask = 0x80000000;
+	static const u32 extcfg_end_mask =    0x30000000;
+	static const int extcfg_end_shift =   28;
+	static const int extcfg_endbus[] =    { 255, 127, 63, 31 };
+	static const u32 extcfg_base_mask =   0x00007fff;
+	static const int extcfg_base_lshift = 25;
+
+	raw_pci_ops->read(0, 0, PCI_DEVFN(0, 0), extcfg_regnum, extcfg_regsize,
+			  &extcfg);
+
+	if (!(extcfg & extcfg_enable_mask))
+		return NULL;
+
+	if (extend_mmcfg(1) == -1)
+		return NULL;
+
+	base = (extcfg & extcfg_base_mask) << extcfg_base_lshift;
+	end = (extcfg & extcfg_end_mask) >> extcfg_end_shift;
+	fill_one_mmcfg(base, 0, 0, extcfg_endbus[end]);
+
+	return "nVidia MCP55";
+}
+
 struct pci_mmcfg_hostbridge_probe {
 	u32 bus;
 	u32 devfn;
@@ -183,6 +213,8 @@ static struct pci_mmcfg_hostbridge_probe
 	  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)