powerpc: Add support for CoreInt delivery of interrupts on MPIC

CoreInt provides a mechansim to deliver the IRQ vector directly
into the core on an interrupt (via the SPR EPR) rather than having
to go IACK on the PIC.  This is suppose to provide an improvment
in interrupt latency by reducing the time to get the IRQ vector.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

2 files changed, 46 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/mpic.h b/arch/powerpc/include/asm/mpic.h
index c2ccca53b991..a002682f3a6d 100644
--- a/arch/powerpc/include/asm/mpic.h
+++ b/arch/powerpc/include/asm/mpic.h
@@ -22,6 +22,14 @@
 #define MPIC_GREG_FEATURE_1             0x00010
 #define MPIC_GREG_GLOBAL_CONF_0         0x00020
 #define         MPIC_GREG_GCONF_RESET                   0x80000000
+/* On the FSL mpic implementations the Mode field is expand to be
+ * 2 bits wide:
+ *      0b00 = pass through (interrupts routed to IRQ0)
+ *      0b01 = Mixed mode
+ *      0b10 = reserved
+ *      0b11 = External proxy / coreint
+ */
+#define         MPIC_GREG_GCONF_COREINT                 0x60000000
 #define         MPIC_GREG_GCONF_8259_PTHROU_DIS         0x20000000
 #define         MPIC_GREG_GCONF_NO_BIAS                 0x10000000
 #define         MPIC_GREG_GCONF_BASE_MASK               0x000fffff
@@ -357,6 +365,8 @@ struct mpic
 #define MPIC_BROKEN_FRR_NIRQS           0x00000800
 /* Destination only supports a single CPU at a time */
 #define MPIC_SINGLE_DEST_CPU            0x00001000
+/* Enable CoreInt delivery of interrupts */
+#define MPIC_ENABLE_COREINT             0x00002000
 
 /* MPIC HW modification ID */
 #define MPIC_REGSET_MASK                0xf0000000
@@ -470,6 +480,8 @@ extern void mpic_end_irq(unsigned int irq);
 extern unsigned int mpic_get_one_irq(struct mpic *mpic);
 /* This one gets from the primary mpic */
 extern unsigned int mpic_get_irq(void);
+/* This one gets from the primary mpic via CoreInt*/
+extern unsigned int mpic_get_coreint_irq(void);
 /* Fetch Machine Check interrupt from primary mpic */
 extern unsigned int mpic_get_mcirq(void);
 
diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index 532e205303a2..21b956701596 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -1170,6 +1170,12 @@ struct mpic * __init mpic_alloc(struct device_node *node,
                         mb();
         }
 
+        /* CoreInt */
+        if (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)
                 mpic_write(mpic->gregs, MPIC_INFO(GREG_GLOBAL_CONF_0),
                            mpic_read(mpic->gregs, MPIC_INFO(GREG_GLOBAL_CONF_0))
@@ -1525,6 +1531,34 @@ unsigned int mpic_get_irq(void)
         return mpic_get_one_irq(mpic);
 }
 
+unsigned int mpic_get_coreint_irq(void)
+{
+#ifdef CONFIG_BOOKE
+        struct mpic *mpic = mpic_primary;
+        u32 src;
+
+        BUG_ON(mpic == NULL);
+
+        src = mfspr(SPRN_EPR);
+
+        if (unlikely(src == mpic->spurious_vec)) {
+                if (mpic->flags & MPIC_SPV_EOI)
+                        mpic_eoi(mpic);
+                return NO_IRQ;
+        }
+        if (unlikely(mpic->protected && test_bit(src, mpic->protected))) {
+                if (printk_ratelimit())
+                        printk(KERN_WARNING "%s: Got protected source %d !\n",
+                               mpic->name, (int)src);
+                return NO_IRQ;
+        }
+
+        return irq_linear_revmap(mpic->irqhost, src);
+#else
+        return NO_IRQ;
+#endif
+}
+
 unsigned int mpic_get_mcirq(void)
 {
         struct mpic *mpic = mpic_primary;