[POWERPC] Enable MSI mappings for MPIC

On some Apple machines the HT MSI mappings are not enabled by firmware, so
we need to do it by hand.

We can't use the pci routines as this code runs too early.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/sysdev/mpic.c

@@ -389,6 +389,50 @@ static void mpic_shutdown_ht_interrupt(struct mpic *mpic, unsigned int source,
 #endif
 }
 
+#ifdef CONFIG_PCI_MSI
+static void __init mpic_scan_ht_msi(struct mpic *mpic, u8 __iomem *devbase,
+				    unsigned int devfn)
+{
+	u8 __iomem *base;
+	u8 pos, flags;
+	u64 addr = 0;
+
+	for (pos = readb(devbase + PCI_CAPABILITY_LIST); pos != 0;
+	     pos = readb(devbase + pos + PCI_CAP_LIST_NEXT)) {
+		u8 id = readb(devbase + pos + PCI_CAP_LIST_ID);
+		if (id == PCI_CAP_ID_HT) {
+			id = readb(devbase + pos + 3);
+			if ((id & HT_5BIT_CAP_MASK) == HT_CAPTYPE_MSI_MAPPING)
+				break;
+		}
+	}
+
+	if (pos == 0)
+		return;
+
+	base = devbase + pos;
+
+	flags = readb(base + HT_MSI_FLAGS);
+	if (!(flags & HT_MSI_FLAGS_FIXED)) {
+		addr = readl(base + HT_MSI_ADDR_LO) & HT_MSI_ADDR_LO_MASK;
+		addr = addr | ((u64)readl(base + HT_MSI_ADDR_HI) << 32);
+	}
+
+	printk(KERN_DEBUG "mpic:   - HT:%02x.%x %s MSI mapping found @ 0x%lx\n",
+		PCI_SLOT(devfn), PCI_FUNC(devfn),
+		flags & HT_MSI_FLAGS_ENABLE ? "enabled" : "disabled", addr);
+
+	if (!(flags & HT_MSI_FLAGS_ENABLE))
+		writeb(flags | HT_MSI_FLAGS_ENABLE, base + HT_MSI_FLAGS);
+}
+#else
+static void __init mpic_scan_ht_msi(struct mpic *mpic, u8 __iomem *devbase,
+				    unsigned int devfn)
+{
+	return;
+}
+#endif
+
 static void __init mpic_scan_ht_pic(struct mpic *mpic, u8 __iomem *devbase,
 				    unsigned int devfn, u32 vdid)
 {
@@ -480,6 +524,7 @@ static void __init mpic_scan_ht_pics(struct mpic *mpic)
 			goto next;
 
 		mpic_scan_ht_pic(mpic, devbase, devfn, l);
+		mpic_scan_ht_msi(mpic, devbase, devfn);
 
 	next:
 		/* next device, if function 0 */