Use more care when implimenting the PCI BIOS functions.

The 'CHECK' function seemed to be both wrong code and the wrong
number, so I have just added the corrct code in parallel.

The READ_CONF and WRITE_CONF functions would both do the wrong thing
if the passed in BDF was not found.  We should return and error to the
caller, but not stop running the option ROM.

Signed-off-by: Mark Marshall <mark.marshall@csr.com>

Index: util/x86emu/x86_interrupts.c
===================================================================
--- util/x86emu/x86_interrupts.c	(revision 4855)
+++ util/x86emu/x86_interrupts.c	(working copy)
@@ -35,13 +35,14 @@
 
 enum {
 	CHECK = 0xb001,
-	FINDDEV = 0xb102,
-	READCONFBYTE = 0xb108,
-	READCONFWORD = 0xb109,
-	READCONFDWORD = 0xb10a,
-	WRITECONFBYTE = 0xb10b,
-	WRITECONFWORD = 0xb10c,
-	WRITECONFDWORD = 0xb10d
+	PCIBIOS_CHECK = 0xb101,
+	PCIBIOS_FINDDEV = 0xb102,
+	PCIBIOS_READCONFBYTE = 0xb108,
+	PCIBIOS_READCONFWORD = 0xb109,
+	PCIBIOS_READCONFDWORD = 0xb10a,
+	PCIBIOS_WRITECONFBYTE = 0xb10b,
+	PCIBIOS_WRITECONFWORD = 0xb10c,
+	PCIBIOS_WRITECONFDWORD = 0xb10d
 };
 
 // errors go in AH. Just set these up so that word assigns
@@ -73,7 +74,12 @@
 		regs->ecx = 0x2049;
 		retval = 0;
 		break;
-	case FINDDEV:
+	case  PCIBIOS_CHECK:
+		regs->edx = 0x20494350; /* ' ICP' */
+		regs->edi = 0x00000000; /* protected mode entry */
+		retval = 0;
+		break;
+	case PCIBIOS_FINDDEV:
 	{
 		devid = regs->ecx;
 		vendorid = regs->edx;
@@ -104,12 +110,12 @@
 		}
 	}
 	break;
-	case READCONFDWORD:
-	case READCONFWORD:
-	case READCONFBYTE:
-	case WRITECONFDWORD:
-	case WRITECONFWORD:
-	case WRITECONFBYTE:
+	case PCIBIOS_READCONFDWORD:
+	case PCIBIOS_READCONFWORD:
+	case PCIBIOS_READCONFBYTE:
+	case PCIBIOS_WRITECONFDWORD:
+	case PCIBIOS_WRITECONFWORD:
+	case PCIBIOS_WRITECONFBYTE:
 	{
 		unsigned long dword;
 		unsigned short word;
@@ -126,39 +132,39 @@
 			regs->eax = PCIBIOS_BADREG;
 			retval = -1;
 		}
-		switch(func) {
-		case READCONFBYTE:
-			byte = pci_read_config8(dev, reg);
-			regs->ecx = byte;
-			break;
-		case READCONFWORD:
-			word = pci_read_config16(dev, reg);
-			regs->ecx = word;
-			break;
-		case READCONFDWORD:
-			dword = pci_read_config32(dev, reg);
-			regs->ecx = dword;
-			break;
-		case WRITECONFBYTE:
-			byte = regs->ecx;
-			pci_write_config8(dev, reg, byte);
-			break;
-		case WRITECONFWORD:
-			word = regs->ecx;
-			pci_write_config16(dev, reg, word);
-			break;
-		case WRITECONFDWORD:
-			dword = regs->ecx;
-			pci_write_config32(dev, reg, dword);
-			break;
+		else {
+		        switch(func) {
+			case PCIBIOS_READCONFBYTE:
+			        byte = pci_read_config8(dev, reg);
+				regs->ecx = byte;
+				break;
+			case PCIBIOS_READCONFWORD:
+			        word = pci_read_config16(dev, reg);
+				regs->ecx = word;
+				break;
+			case PCIBIOS_READCONFDWORD:
+			        dword = pci_read_config32(dev, reg);
+				regs->ecx = dword;
+				break;
+			case PCIBIOS_WRITECONFBYTE:
+			        byte = regs->ecx;
+				pci_write_config8(dev, reg, byte);
+				break;
+			case PCIBIOS_WRITECONFWORD:
+			        word = regs->ecx;
+				pci_write_config16(dev, reg, word);
+				break;
+			case PCIBIOS_WRITECONFDWORD:
+			        dword = regs->ecx;
+				pci_write_config32(dev, reg, dword);
+				break;
+			}
+			
+			printk(BIOS_DEBUG, "0x%x: bus %d devfn 0x%x reg 0x%x val 0x%x\n",
+			       func, bus, devfn, reg, regs->ecx);
+			regs->eax = 0;
+			retval = 0;
 		}
-
-		if (retval)
-			retval = PCIBIOS_BADREG;
-		printk(BIOS_DEBUG, "0x%x: bus %d devfn 0x%x reg 0x%x val 0x%x\n",
-			     func, bus, devfn, reg, regs->ecx);
-		regs->eax = 0;
-		retval = 0;
 	}
 	break;
 	default: