powerpc/pasemi: Fix Nemo SB600 i8259 interrupts.

The device tree on the Nemo passes all of the i8259 interrupts with
numbers between 212 and 222, and points their interrupt-parent property
to the pasemi-opic, requiring custom patches to the kernel. Fix the
values so that they can be controlled by the generic ppc i8259 code.
Signed-off-by: Darren Stevens <darren@stevens-zone.net>
[mpe: Rework deeply nested if and boundary checks]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/prom_init.c

@@ -2644,6 +2644,70 @@ static void __init fixup_device_tree_efika(void)
 #define fixup_device_tree_efika()
 #endif
 
+#ifdef CONFIG_PPC_PASEMI_NEMO
+/*
+ * CFE supplied on Nemo is broken in several ways, biggest
+ * problem is that it reassigns ISA interrupts to unused mpic ints.
+ * Add an interrupt-controller property for the io-bridge to use
+ * and correct the ints so we can attach them to an irq_domain
+ */
+static void __init fixup_device_tree_pasemi(void)
+{
+	u32 interrupts[2], parent, rval, val = 0;
+	char *name, *pci_name;
+	phandle iob, node;
+
+	/* Find the root pci node */
+	name = "/pxp@0,e0000000";
+	iob = call_prom("finddevice", 1, 1, ADDR(name));
+	if (!PHANDLE_VALID(iob))
+		return;
+
+	/* check if interrupt-controller node set yet */
+	if (prom_getproplen(iob, "interrupt-controller") !=PROM_ERROR)
+		return;
+
+	prom_printf("adding interrupt-controller property for SB600...\n");
+
+	prom_setprop(iob, name, "interrupt-controller", &val, 0);
+
+	pci_name = "/pxp@0,e0000000/pci@11";
+	node = call_prom("finddevice", 1, 1, ADDR(pci_name));
+	parent = ADDR(iob);
+
+	for( ; prom_next_node(&node); ) {
+		/* scan each node for one with an interrupt */
+		if (!PHANDLE_VALID(node))
+			continue;
+
+		rval = prom_getproplen(node, "interrupts");
+		if (rval == 0 || rval == PROM_ERROR)
+			continue;
+
+		prom_getprop(node, "interrupts", &interrupts, sizeof(interrupts));
+		if ((interrupts[0] < 212) || (interrupts[0] > 222))
+			continue;
+
+		/* found a node, update both interrupts and interrupt-parent */
+		if ((interrupts[0] >= 212) && (interrupts[0] <= 215))
+			interrupts[0] -= 203;
+		if ((interrupts[0] >= 216) && (interrupts[0] <= 220))
+			interrupts[0] -= 213;
+		if (interrupts[0] == 221)
+			interrupts[0] = 14;
+		if (interrupts[0] == 222)
+			interrupts[0] = 8;
+
+		prom_setprop(node, pci_name, "interrupts", interrupts,
+					sizeof(interrupts));
+		prom_setprop(node, pci_name, "interrupt-parent", &parent,
+					sizeof(parent));
+	}
+}
+#else	/* !CONFIG_PPC_PASEMI_NEMO */
+static inline void fixup_device_tree_pasemi(void) { }
+#endif
+
 static void __init fixup_device_tree(void)
 {
 	fixup_device_tree_maple();
@@ -2651,6 +2715,7 @@ static void __init fixup_device_tree(void)
 	fixup_device_tree_chrp();
 	fixup_device_tree_pmac();
 	fixup_device_tree_efika();
+	fixup_device_tree_pasemi();
 }
 
 static void __init prom_find_boot_cpu(void)