powerpc: Make MPIC honor the "pic-no-reset" device tree property

This property, defined in the Open PIC binding, tells the kernel not to use
the reset bit in the global configuration register.  Additionally, its
presence mandates that only sources which are actually used (i.e. appear in
the device tree) should have their VECPRI bits initialized.

Although, "pic-no-reset" can be used for the same use cases that
"protected-sources" is covering, the "protected-sources" implementation was
left completely intact.  This is a more pragmatic approach as there are
already several existing systems which use protected sources.  If
"pic-no-reset" *and* "protected-sources" are both used, however, then
"pic-no-reset" takes precedence in terms of the init behavior and the
sanity checks done by protected sources will still take place.

Signed-off-by: Meador Inge <meador_inge@mentor.com>
Cc: Hollis Blanchard <hollis_blanchard@mentor.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/include/asm/mpic.h b/arch/powerpc/include/asm/mpic.h
index 946ec4947da282e90589a3012c8fb92653ecc5f2..7005ee0b074d744e6905fd8e0c6dfc144a3a4cb3 100644 (file)
--- a/arch/powerpc/include/asm/mpic.h
+++ b/arch/powerpc/include/asm/mpic.h
@@ -367,6 +367,10 @@ struct mpic
 #define MPIC_SINGLE_DEST_CPU           0x00001000
 /* Enable CoreInt delivery of interrupts */
 #define MPIC_ENABLE_COREINT            0x00002000
+/* Disable resetting of the MPIC.
+ * NOTE: This flag trumps MPIC_WANTS_RESET.
+ */
+#define MPIC_NO_RESET                  0x00004000
 
 /* MPIC HW modification ID */
 #define MPIC_REGSET_MASK               0xf0000000

diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index eb7021815e2da0c28e6bdc85be746e7135acd415..3bf71035ff506df78d62a9f1558c27146ed66787 100644 (file)
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -913,6 +913,20 @@ void mpic_set_vector(unsigned int virq, unsigned int vector)
        mpic_irq_write(src, MPIC_INFO(IRQ_VECTOR_PRI), vecpri);
 }
 
+void mpic_set_destination(unsigned int virq, unsigned int cpuid)
+{
+       struct mpic *mpic = mpic_from_irq(virq);
+       unsigned int src = mpic_irq_to_hw(virq);
+
+       DBG("mpic: set_destination(mpic:@%p,virq:%d,src:%d,cpuid:0x%x)\n",
+           mpic, virq, src, cpuid);
+
+       if (src >= mpic->irq_count)
+               return;
+
+       mpic_irq_write(src, MPIC_INFO(IRQ_DESTINATION), 1 << cpuid);
+}
+
 static struct irq_chip mpic_irq_chip = {
        .irq_mask       = mpic_mask_irq,
        .irq_unmask     = mpic_unmask_irq,
@@ -993,6 +1007,21 @@ static int mpic_host_map(struct irq_host *h, unsigned int virq,
        /* Set default irq type */
        set_irq_type(virq, IRQ_TYPE_NONE);
 
+       /* If the MPIC was reset, then all vectors have already been
+        * initialized.  Otherwise, a per source lazy initialization
+        * is done here.
+        */
+       if (!mpic_is_ipi(mpic, hw) && (mpic->flags & MPIC_NO_RESET)) {
+               unsigned int cpu = 0;
+
+               if (mpic->flags & MPIC_PRIMARY)
+                       cpu = hard_smp_processor_id();
+
+               mpic_set_vector(virq, hw);
+               mpic_set_destination(virq, cpu);
+               mpic_irq_set_priority(virq, 8);
+       }
+
        return 0;
 }
 
@@ -1040,6 +1069,11 @@ static struct irq_host_ops mpic_host_ops = {
        .xlate = mpic_host_xlate,
 };
 
+static int mpic_reset_prohibited(struct device_node *node)
+{
+       return node && of_get_property(node, "pic-no-reset", NULL);
+}
+
 /*
  * Exported functions
  */
@@ -1160,7 +1194,15 @@ struct mpic * __init mpic_alloc(struct device_node *node,
        mpic_map(mpic, node, paddr, &mpic->tmregs, MPIC_INFO(TIMER_BASE), 0x1000);
 
        /* Reset */
-       if (flags & MPIC_WANTS_RESET) {
+
+       /* When using a device-node, reset requests are only honored if the MPIC
+        * is allowed to reset.
+        */
+       if (mpic_reset_prohibited(node))
+               mpic->flags |= MPIC_NO_RESET;
+
+       if ((flags & MPIC_WANTS_RESET) && !(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))
                           | MPIC_GREG_GCONF_RESET);
@@ -1325,17 +1367,19 @@ void __init mpic_init(struct mpic *mpic)
        else
                cpu = 0;
 
-       for (i = 0; i < mpic->num_sources; i++) {
-               /* start with vector = source number, and masked */
-               u32 vecpri = MPIC_VECPRI_MASK | i |
-                       (8 << MPIC_VECPRI_PRIORITY_SHIFT);
+       if (!(mpic->flags & MPIC_NO_RESET)) {
+               for (i = 0; i < mpic->num_sources; i++) {
+                       /* start with vector = source number, and masked */
+                       u32 vecpri = MPIC_VECPRI_MASK | i |
+                               (8 << MPIC_VECPRI_PRIORITY_SHIFT);
                
-               /* check if protected */
-               if (mpic->protected && test_bit(i, mpic->protected))
-                       continue;
-               /* init hw */
-               mpic_irq_write(i, MPIC_INFO(IRQ_VECTOR_PRI), vecpri);
-               mpic_irq_write(i, MPIC_INFO(IRQ_DESTINATION), 1 << cpu);
+                       /* check if protected */
+                       if (mpic->protected && test_bit(i, mpic->protected))
+                               continue;
+                       /* init hw */
+                       mpic_irq_write(i, MPIC_INFO(IRQ_VECTOR_PRI), vecpri);
+                       mpic_irq_write(i, MPIC_INFO(IRQ_DESTINATION), 1 << cpu);
+               }
        }
        
        /* Init spurious vector */