3 files changed, 34 insertions, 20 deletions

diff --git a/Documentation/devicetree/bindings/powerpc/fsl/mpic.txt b/Documentation/devicetree/bindings/powerpc/fsl/mpic.txt
index b393ccf1e9f3..dc5744636a57 100644
--- a/Documentation/devicetree/bindings/powerpc/fsl/mpic.txt
+++ b/Documentation/devicetree/bindings/powerpc/fsl/mpic.txt
@@ -70,6 +70,13 @@ PROPERTIES
           If present the MPIC will be assumed to only be able to route
           non-IPI interrupts to a single CPU at a time (EG: Freescale MPIC).
 
+  - last-interrupt-source
+      Usage: optional
+      Value type: <u32>
+          Some MPICs do not correctly report the number of hardware sources
+          in the global feature registers.  If specified, this field will
+          override the value read from MPIC_GREG_FEATURE_LAST_SRC.
+
 INTERRUPT SPECIFIER DEFINITION
 
   Interrupt specifiers consists of 4 cells encoded as
diff --git a/arch/powerpc/boot/dts/fsl/pq3-mpic.dtsi b/arch/powerpc/boot/dts/fsl/pq3-mpic.dtsi
index 658bd81982cb..fdedf7b1fe0f 100644
--- a/arch/powerpc/boot/dts/fsl/pq3-mpic.dtsi
+++ b/arch/powerpc/boot/dts/fsl/pq3-mpic.dtsi
@@ -41,6 +41,7 @@ mpic: pic@40000 {
         device_type = "open-pic";
         big-endian;
         single-cpu-affinity;
+        last-interrupt-source = <255>;
 };
 
 timer@41100 {
diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index cbffeb742d66..90171d447c3d 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -1149,6 +1149,7 @@ struct mpic * __init mpic_alloc(struct device_node *node,
         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[] = {
@@ -1220,7 +1221,6 @@ struct mpic * __init mpic_alloc(struct device_node *node,
         mpic->hc_tm = mpic_tm_chip;
         mpic->hc_tm.name = name;
 
-        mpic->isu_size = isu_size;
         mpic->num_sources = 0; /* so far */
 
         if (mpic->flags & MPIC_LARGE_VECTORS)
@@ -1308,20 +1308,6 @@ struct mpic * __init mpic_alloc(struct device_node *node,
                            | 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 (irq_count)
-                        mpic->num_sources = 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.
          */
@@ -1336,18 +1322,38 @@ struct mpic * __init mpic_alloc(struct device_node *node,
                          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.
+         */
+        last_irq = (greg_feature & MPIC_GREG_FEATURE_LAST_SRC_MASK)
+                                >> MPIC_GREG_FEATURE_LAST_SRC_SHIFT;
+        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_alloc_host(mpic->node, IRQ_HOST_MAP_LINEAR,
-                                       isu_size ? isu_size : mpic->num_sources,
-                                       &mpic_host_ops, intvec_top + 1);
+                                       mpic->isu_size, &mpic_host_ops,
+                                       intvec_top + 1);
 
         /*
          * FIXME: The code leaks the MPIC object and mappings here; this