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authorKevin D. Kissell <kevink@mips.com>2007-08-03 19:38:03 +0200
committerRalf Baechle <ralf@linux-mips.org>2007-10-11 23:45:57 +0100
commitf571eff0a24ed97a919f2b61bb4afdeab4b43002 (patch)
treee9d6c597fafca02720f000cf795a37f2d163f10f /arch/mips/kernel/smtc.c
parentbbf25010f1a6b761914430f5fca081ec8c7accd1 (diff)
downloadlinux-f571eff0a24ed97a919f2b61bb4afdeab4b43002.tar.bz2
[MIPS] IRQ Affinity Support for SMTC on Malta Platform
Signed-off-by: Kevin D. Kissell <kevink@mips.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel/smtc.c')
-rw-r--r--arch/mips/kernel/smtc.c63
1 files changed, 63 insertions, 0 deletions
diff --git a/arch/mips/kernel/smtc.c b/arch/mips/kernel/smtc.c
index f09404377ef1..fe22387d58b1 100644
--- a/arch/mips/kernel/smtc.c
+++ b/arch/mips/kernel/smtc.c
@@ -606,6 +606,60 @@ int setup_irq_smtc(unsigned int irq, struct irqaction * new,
return setup_irq(irq, new);
}
+#ifdef CONFIG_MIPS_MT_SMTC_IRQAFF
+/*
+ * Support for IRQ affinity to TCs
+ */
+
+void smtc_set_irq_affinity(unsigned int irq, cpumask_t affinity)
+{
+ /*
+ * If a "fast path" cache of quickly decodable affinity state
+ * is maintained, this is where it gets done, on a call up
+ * from the platform affinity code.
+ */
+}
+
+void smtc_forward_irq(unsigned int irq)
+{
+ int target;
+
+ /*
+ * OK wise guy, now figure out how to get the IRQ
+ * to be serviced on an authorized "CPU".
+ *
+ * Ideally, to handle the situation where an IRQ has multiple
+ * eligible CPUS, we would maintain state per IRQ that would
+ * allow a fair distribution of service requests. Since the
+ * expected use model is any-or-only-one, for simplicity
+ * and efficiency, we just pick the easiest one to find.
+ */
+
+ target = first_cpu(irq_desc[irq].affinity);
+
+ /*
+ * We depend on the platform code to have correctly processed
+ * IRQ affinity change requests to ensure that the IRQ affinity
+ * mask has been purged of bits corresponding to nonexistent and
+ * offline "CPUs", and to TCs bound to VPEs other than the VPE
+ * connected to the physical interrupt input for the interrupt
+ * in question. Otherwise we have a nasty problem with interrupt
+ * mask management. This is best handled in non-performance-critical
+ * platform IRQ affinity setting code, to minimize interrupt-time
+ * checks.
+ */
+
+ /* If no one is eligible, service locally */
+ if (target >= NR_CPUS) {
+ do_IRQ_no_affinity(irq);
+ return;
+ }
+
+ smtc_send_ipi(target, IRQ_AFFINITY_IPI, irq);
+}
+
+#endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */
+
/*
* IPI model for SMTC is tricky, because interrupts aren't TC-specific.
* Within a VPE one TC can interrupt another by different approaches.
@@ -830,6 +884,15 @@ void ipi_decode(struct smtc_ipi *pipi)
break;
}
break;
+#ifdef CONFIG_MIPS_MT_SMTC_IRQAFF
+ case IRQ_AFFINITY_IPI:
+ /*
+ * Accept a "forwarded" interrupt that was initially
+ * taken by a TC who doesn't have affinity for the IRQ.
+ */
+ do_IRQ_no_affinity((int)arg_copy);
+ break;
+#endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */
default:
printk("Impossible SMTC IPI Type 0x%x\n", type_copy);
break;