powerpc/mpic: Add in-core support for cascaded MPICs

The Cell and PowerMac platforms use virtually identical cascaded-IRQ
setup code, so just merge it into the core.  Ideally this code would
trigger automatically when an MPIC device-node specifies an "interrupts"
property, perhaps even enabling MPIC_SECONDARY along the way.

Unfortunately, Benjamin Herrenschmidt has had bad experiences in the
past with the quality of Apple PowerMac device-trees, so to be safe we
will only try to parse out an IRQ if the MPIC_SECONDARY flag is set by
the caller.

Signed-off-by: Kyle Moffett <Kyle.D.Moffett@boeing.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

3 files changed, 33 insertions, 56 deletions

diff --git a/arch/powerpc/platforms/cell/setup.c b/arch/powerpc/platforms/cell/setup.c
index cd00ca856038..62002a7edfed 100644
--- a/arch/powerpc/platforms/cell/setup.c
+++ b/arch/powerpc/platforms/cell/setup.c
@@ -184,24 +184,10 @@ static int __init cell_publish_devices(void)
 }
 machine_subsys_initcall(cell, cell_publish_devices);
 
-static void cell_mpic_cascade(unsigned int irq, struct irq_desc *desc)
-{
-        struct irq_chip *chip = irq_desc_get_chip(desc);
-        struct mpic *mpic = irq_desc_get_handler_data(desc);
-        unsigned int virq;
-
-        virq = mpic_get_one_irq(mpic);
-        if (virq != NO_IRQ)
-                generic_handle_irq(virq);
-
-        chip->irq_eoi(&desc->irq_data);
-}
-
 static void __init mpic_init_IRQ(void)
 {
         struct device_node *dn;
         struct mpic *mpic;
-        unsigned int virq;
 
         for (dn = NULL;
              (dn = of_find_node_by_name(dn, "interrupt-controller"));) {
@@ -215,15 +201,6 @@ static void __init mpic_init_IRQ(void)
                 if (mpic == NULL)
                         continue;
                 mpic_init(mpic);
-
-                virq = irq_of_parse_and_map(dn, 0);
-                if (virq == NO_IRQ)
-                        continue;
-
-                printk(KERN_INFO "%s : hooking up to IRQ %d\n",
-                       dn->full_name, virq);
-                irq_set_handler_data(virq, mpic);
-                irq_set_chained_handler(virq, cell_mpic_cascade);
         }
 }
 
diff --git a/arch/powerpc/platforms/powermac/pic.c b/arch/powerpc/platforms/powermac/pic.c
index b962101744e5..d8aedf135bb6 100644
--- a/arch/powerpc/platforms/powermac/pic.c
+++ b/arch/powerpc/platforms/powermac/pic.c
@@ -464,18 +464,6 @@ int of_irq_map_oldworld(struct device_node *device, int index,
 }
 #endif /* CONFIG_PPC32 */
 
-static void pmac_u3_cascade(unsigned int irq, struct irq_desc *desc)
-{
-        struct irq_chip *chip = irq_desc_get_chip(desc);
-        struct mpic *mpic = irq_desc_get_handler_data(desc);
-        unsigned int cascade_irq = mpic_get_one_irq(mpic);
-
-        if (cascade_irq != NO_IRQ)
-                generic_handle_irq(cascade_irq);
-
-        chip->irq_eoi(&desc->irq_data);
-}
-
 static void __init pmac_pic_setup_mpic_nmi(struct mpic *mpic)
 {
 #if defined(CONFIG_XMON) && defined(CONFIG_PPC32)
@@ -526,7 +514,6 @@ static int __init pmac_pic_probe_mpic(void)
 {
         struct mpic *mpic1, *mpic2;
         struct device_node *np, *master = NULL, *slave = NULL;
-        unsigned int cascade;
 
         /* We can have up to 2 MPICs cascaded */
         for (np = NULL; (np = of_find_node_by_type(np, "open-pic"))
@@ -562,27 +549,14 @@ static int __init pmac_pic_probe_mpic(void)
 
         of_node_put(master);
 
-        /* No slave, let's go out */
-        if (slave == NULL)
-                return 0;
-
-        /* Get/Map slave interrupt */
-        cascade = irq_of_parse_and_map(slave, 0);
-        if (cascade == NO_IRQ) {
-                printk(KERN_ERR "Failed to map cascade IRQ\n");
-                return 0;
-        }
-
-        mpic2 = pmac_setup_one_mpic(slave, 0);
-        if (mpic2 == NULL) {
-                printk(KERN_ERR "Failed to setup slave MPIC\n");
+        /* Set up a cascaded controller, if present */
+        if (slave) {
+                mpic2 = pmac_setup_one_mpic(slave, 0);
+                if (mpic2 == NULL)
+                        printk(KERN_ERR "Failed to setup slave MPIC\n");
                 of_node_put(slave);
-                return 0;
         }
-        irq_set_handler_data(cascade, mpic2);
-        irq_set_chained_handler(cascade, pmac_u3_cascade);
 
-        of_node_put(slave);
         return 0;
 }
 
diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index 76110608543a..4e9ccb1015de 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -1111,6 +1111,22 @@ static int mpic_host_xlate(struct irq_host *h, struct device_node *ct,
         return 0;
 }
 
+/* IRQ handler for a secondary MPIC cascaded from another IRQ controller */
+static void mpic_cascade(unsigned int irq, struct irq_desc *desc)
+{
+        struct irq_chip *chip = irq_desc_get_chip(desc);
+        struct mpic *mpic = irq_desc_get_handler_data(desc);
+        unsigned int virq;
+
+        BUG_ON(!(mpic->flags & MPIC_SECONDARY));
+
+        virq = mpic_get_one_irq(mpic);
+        if (virq != NO_IRQ)
+                generic_handle_irq(virq);
+
+        chip->irq_eoi(&desc->irq_data);
+}
+
 static struct irq_host_ops mpic_host_ops = {
         .match = mpic_host_match,
         .map = mpic_host_map,
@@ -1402,8 +1418,7 @@ void __init mpic_set_default_senses(struct mpic *mpic, u8 *senses, int count)
 
 void __init mpic_init(struct mpic *mpic)
 {
-        int i;
-        int cpu;
+        int i, cpu;
 
         BUG_ON(mpic->num_sources == 0);
 
@@ -1488,6 +1503,17 @@ void __init mpic_init(struct mpic *mpic)
                                   GFP_KERNEL);
         BUG_ON(mpic->save_data == NULL);
 #endif
+
+        /* Check if this MPIC is chained from a parent interrupt controller */
+        if (mpic->flags & MPIC_SECONDARY) {
+                int virq = irq_of_parse_and_map(mpic->node, 0);
+                if (virq != NO_IRQ) {
+                        printk(KERN_INFO "%s: hooking up to IRQ %d\n",
+                                        mpic->node->full_name, virq);
+                        irq_set_handler_data(virq, mpic);
+                        irq_set_chained_handler(virq, &mpic_cascade);
+                }
+        }
 }
 
 void __init mpic_set_clk_ratio(struct mpic *mpic, u32 clock_ratio)