diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index c83a512..9ac71eb 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -873,7 +873,7 @@
 	DBG("mpic: set_irq_type(mpic:@%p,virq:%d,src:0x%x,type:0x%x)\n",
 	    mpic, d->irq, src, flow_type);
 
-	if (src >= mpic->irq_count)
+	if (src >= mpic->num_sources)
 		return -EINVAL;
 
 	if (flow_type == IRQ_TYPE_NONE)
@@ -909,7 +909,7 @@
 	DBG("mpic: set_vector(mpic:@%p,virq:%d,src:%d,vector:0x%x)\n",
 	    mpic, virq, src, vector);
 
-	if (src >= mpic->irq_count)
+	if (src >= mpic->num_sources)
 		return;
 
 	vecpri = mpic_irq_read(src, MPIC_INFO(IRQ_VECTOR_PRI));
@@ -926,7 +926,7 @@
 	DBG("mpic: set_destination(mpic:@%p,virq:%d,src:%d,cpuid:0x%x)\n",
 	    mpic, virq, src, cpuid);
 
-	if (src >= mpic->irq_count)
+	if (src >= mpic->num_sources)
 		return;
 
 	mpic_irq_write(src, MPIC_INFO(IRQ_DESTINATION), 1 << cpuid);
@@ -1006,7 +1006,7 @@
 		return 0;
 	}
 
-	if (hw >= mpic->irq_count)
+	if (hw >= mpic->num_sources)
 		return -EINVAL;
 
 	mpic_msi_reserve_hwirq(mpic, hw);
@@ -1149,6 +1149,7 @@
 	u32 greg_feature;
 	const char *vers;
 	const u32 *psrc;
+	u32 last_irq;
 
 	/* Default MPIC search parameters */
 	static const struct of_device_id __initconst mpic_device_id[] = {
@@ -1182,6 +1183,16 @@
 		}
 	}
 
+	/* Read extra device-tree properties into the flags variable */
+	if (of_get_property(node, "big-endian", NULL))
+		flags |= MPIC_BIG_ENDIAN;
+	if (of_get_property(node, "pic-no-reset", NULL))
+		flags |= MPIC_NO_RESET;
+	if (of_get_property(node, "single-cpu-affinity", NULL))
+		flags |= MPIC_SINGLE_DEST_CPU;
+	if (of_device_is_compatible(node, "fsl,mpic"))
+		flags |= MPIC_FSL;
+
 	mpic = kzalloc(sizeof(struct mpic), GFP_KERNEL);
 	if (mpic == NULL)
 		goto err_of_node_put;
@@ -1189,15 +1200,16 @@
 	mpic->name = name;
 	mpic->node = node;
 	mpic->paddr = phys_addr;
+	mpic->flags = flags;
 
 	mpic->hc_irq = mpic_irq_chip;
 	mpic->hc_irq.name = name;
-	if (!(flags & MPIC_SECONDARY))
+	if (!(mpic->flags & MPIC_SECONDARY))
 		mpic->hc_irq.irq_set_affinity = mpic_set_affinity;
 #ifdef CONFIG_MPIC_U3_HT_IRQS
 	mpic->hc_ht_irq = mpic_irq_ht_chip;
 	mpic->hc_ht_irq.name = name;
-	if (!(flags & MPIC_SECONDARY))
+	if (!(mpic->flags & MPIC_SECONDARY))
 		mpic->hc_ht_irq.irq_set_affinity = mpic_set_affinity;
 #endif /* CONFIG_MPIC_U3_HT_IRQS */
 
@@ -1209,12 +1221,9 @@
 	mpic->hc_tm = mpic_tm_chip;
 	mpic->hc_tm.name = name;
 
-	mpic->flags = flags;
-	mpic->isu_size = isu_size;
-	mpic->irq_count = irq_count;
 	mpic->num_sources = 0; /* so far */
 
-	if (flags & MPIC_LARGE_VECTORS)
+	if (mpic->flags & MPIC_LARGE_VECTORS)
 		intvec_top = 2047;
 	else
 		intvec_top = 255;
@@ -1233,12 +1242,6 @@
 	mpic->ipi_vecs[3]   = intvec_top - 1;
 	mpic->spurious_vec  = intvec_top;
 
-	/* Check for "big-endian" in device-tree */
-	if (of_get_property(mpic->node, "big-endian", NULL) != NULL)
-		mpic->flags |= MPIC_BIG_ENDIAN;
-	if (of_device_is_compatible(mpic->node, "fsl,mpic"))
-		mpic->flags |= MPIC_FSL;
-
 	/* Look for protected sources */
 	psrc = of_get_property(mpic->node, "protected-sources", &psize);
 	if (psrc) {
@@ -1254,11 +1257,11 @@
 	}
 
 #ifdef CONFIG_MPIC_WEIRD
-	mpic->hw_set = mpic_infos[MPIC_GET_REGSET(flags)];
+	mpic->hw_set = mpic_infos[MPIC_GET_REGSET(mpic->flags)];
 #endif
 
 	/* default register type */
-	if (flags & MPIC_BIG_ENDIAN)
+	if (mpic->flags & MPIC_BIG_ENDIAN)
 		mpic->reg_type = mpic_access_mmio_be;
 	else
 		mpic->reg_type = mpic_access_mmio_le;
@@ -1268,10 +1271,10 @@
 	 * only if the kernel includes DCR support.
 	 */
 #ifdef CONFIG_PPC_DCR
-	if (flags & MPIC_USES_DCR)
+	if (mpic->flags & MPIC_USES_DCR)
 		mpic->reg_type = mpic_access_dcr;
 #else
-	BUG_ON(flags & MPIC_USES_DCR);
+	BUG_ON(mpic->flags & MPIC_USES_DCR);
 #endif
 
 	/* Map the global registers */
@@ -1283,10 +1286,7 @@
 	/* When using a device-node, reset requests are only honored if the MPIC
 	 * is allowed to reset.
 	 */
-	if (of_get_property(mpic->node, "pic-no-reset", NULL))
-		mpic->flags |= MPIC_NO_RESET;
-
-	if ((flags & MPIC_WANTS_RESET) && !(mpic->flags & MPIC_NO_RESET)) {
+	if (!(mpic->flags & MPIC_NO_RESET)) {
 		printk(KERN_DEBUG "mpic: Resetting\n");
 		mpic_write(mpic->gregs, MPIC_INFO(GREG_GLOBAL_CONF_0),
 			   mpic_read(mpic->gregs, MPIC_INFO(GREG_GLOBAL_CONF_0))
@@ -1297,31 +1297,17 @@
 	}
 
 	/* CoreInt */
-	if (flags & MPIC_ENABLE_COREINT)
+	if (mpic->flags & MPIC_ENABLE_COREINT)
 		mpic_write(mpic->gregs, MPIC_INFO(GREG_GLOBAL_CONF_0),
 			   mpic_read(mpic->gregs, MPIC_INFO(GREG_GLOBAL_CONF_0))
 			   | MPIC_GREG_GCONF_COREINT);
 
-	if (flags & MPIC_ENABLE_MCK)
+	if (mpic->flags & MPIC_ENABLE_MCK)
 		mpic_write(mpic->gregs, MPIC_INFO(GREG_GLOBAL_CONF_0),
 			   mpic_read(mpic->gregs, MPIC_INFO(GREG_GLOBAL_CONF_0))
 			   | MPIC_GREG_GCONF_MCK);
 
 	/*
-	 * Read feature register.  For non-ISU MPICs, num sources as well. On
-	 * ISU MPICs, sources are counted as ISUs are added
-	 */
-	greg_feature = mpic_read(mpic->gregs, MPIC_INFO(GREG_FEATURE_0));
-	if (isu_size == 0) {
-		if (flags & MPIC_BROKEN_FRR_NIRQS)
-			mpic->num_sources = mpic->irq_count;
-		else
-			mpic->num_sources =
-				((greg_feature & MPIC_GREG_FEATURE_LAST_SRC_MASK)
-				 >> MPIC_GREG_FEATURE_LAST_SRC_SHIFT) + 1;
-	}
-
-	/*
 	 * The MPIC driver will crash if there are more cores than we
 	 * can initialize, so we may as well catch that problem here.
 	 */
@@ -1336,17 +1322,41 @@
 			 0x1000);
 	}
 
+	/*
+	 * Read feature register.  For non-ISU MPICs, num sources as well. On
+	 * ISU MPICs, sources are counted as ISUs are added
+	 */
+	greg_feature = mpic_read(mpic->gregs, MPIC_INFO(GREG_FEATURE_0));
+
+	/*
+	 * By default, the last source number comes from the MPIC, but the
+	 * device-tree and board support code can override it on buggy hw.
+	 * If we get passed an isu_size (multi-isu MPIC) then we use that
+	 * as a default instead of the value read from the HW.
+	 */
+	last_irq = (greg_feature & MPIC_GREG_FEATURE_LAST_SRC_MASK)
+				>> MPIC_GREG_FEATURE_LAST_SRC_SHIFT;	
+	if (isu_size)
+		last_irq = isu_size  * MPIC_MAX_ISU - 1;
+	of_property_read_u32(mpic->node, "last-interrupt-source", &last_irq);
+	if (irq_count)
+		last_irq = irq_count - 1;
+
 	/* Initialize main ISU if none provided */
-	if (mpic->isu_size == 0) {
-		mpic->isu_size = mpic->num_sources;
+	if (!isu_size) {
+		isu_size = last_irq + 1;
+		mpic->num_sources = isu_size;
 		mpic_map(mpic, mpic->paddr, &mpic->isus[0],
-			 MPIC_INFO(IRQ_BASE), MPIC_INFO(IRQ_STRIDE) * mpic->isu_size);
+				MPIC_INFO(IRQ_BASE),
+				MPIC_INFO(IRQ_STRIDE) * isu_size);
 	}
+
+	mpic->isu_size = isu_size;
 	mpic->isu_shift = 1 + __ilog2(mpic->isu_size - 1);
 	mpic->isu_mask = (1 << mpic->isu_shift) - 1;
 
 	mpic->irqhost = irq_domain_add_linear(mpic->node,
-				       isu_size ? isu_size : mpic->num_sources,
+				       last_irq + 1,
 				       &mpic_host_ops, mpic);
 
 	/*
@@ -1380,7 +1390,7 @@
 	mpic->next = mpics;
 	mpics = mpic;
 
-	if (!(flags & MPIC_SECONDARY)) {
+	if (!(mpic->flags & MPIC_SECONDARY)) {
 		mpic_primary = mpic;
 		irq_set_default_host(mpic->irqhost);
 	}
@@ -1447,10 +1457,6 @@
 			       (mpic->ipi_vecs[0] + i));
 	}
 
-	/* Initialize interrupt sources */
-	if (mpic->irq_count == 0)
-		mpic->irq_count = mpic->num_sources;
-
 	/* Do the HT PIC fixups on U3 broken mpic */
 	DBG("MPIC flags: %x\n", mpic->flags);
 	if ((mpic->flags & MPIC_U3_HT_IRQS) && !(mpic->flags & MPIC_SECONDARY)) {