[PATCH 08/18] xen: bind pirq to vector and event channel

[Jeremy Fitzhardinge <jeremy@goop.org>]

Impact: program IO APICs under Xen

Having converting a dev+pin to a gsi, and that gsi to an irq, and
allocated a vector for the irq, we must program the IO APIC to deliver
an interrupt on a pin to the vector, so Xen can deliver it as an event
channel.

Given the pirq, we can get the gsi and vector.  We map the gsi to a
specific IO APIC's pin, and set the routing entry.

(We were passing the ACPI triggering and polarity levels directly into
the apic - but they have reversed values.  The result was that
all the level-triggered interrupts were edge, and vice-versa.
It's surprising that anything worked at all, but now AHCI works
for me.

Thanks for Gerd Hoffmann for noticing this.)

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
 arch/x86/xen/apic.c |    4 ++--
 arch/x86/xen/pci.c  |   32 ++++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c
index 17736a0..e9d9ea7 100644
--- a/arch/x86/xen/apic.c
+++ b/arch/x86/xen/apic.c
@@ -4,6 +4,7 @@
 
 #include <asm/io_apic.h>
 #include <asm/acpi.h>
+#include <asm/hw_irq.h>
 
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>
@@ -13,8 +14,7 @@
 
 void __init xen_io_apic_init(void)
 {
-	printk("xen apic init\n");
-	dump_stack();
+	enable_IO_APIC();
 }
 
 unsigned int xen_io_apic_read(unsigned apic, unsigned reg)
diff --git a/arch/x86/xen/pci.c b/arch/x86/xen/pci.c
index f450007..0f3663c 100644
--- a/arch/x86/xen/pci.c
+++ b/arch/x86/xen/pci.c
@@ -2,6 +2,8 @@
 #include <linux/acpi.h>
 #include <linux/pci.h>
 
+#include <asm/mpspec.h>
+#include <asm/io_apic.h>
 #include <asm/pci_x86.h>
 
 #include <asm/xen/hypervisor.h>
@@ -11,6 +13,31 @@
 
 #include "xen-ops.h"
 
+static void xen_set_io_apic_routing(int irq, int trigger, int polarity)
+{
+	int ioapic, ioapic_pin;
+	int vector, gsi;
+	struct IO_APIC_route_entry entry;
+
+	gsi = xen_gsi_from_irq(irq);
+	vector = xen_vector_from_irq(irq);
+
+	ioapic = mp_find_ioapic(gsi);
+	if (ioapic == -1) {
+		printk(KERN_WARNING "xen_set_ioapic_routing: irq %d gsi %d ioapic %d\n",
+			irq, gsi, ioapic);
+		return;
+	}
+
+	ioapic_pin = mp_find_ioapic_pin(ioapic, gsi);
+
+	printk(KERN_INFO "xen_set_ioapic_routing: irq %d gsi %d vector %d ioapic %d pin %d triggering %d polarity %d\n",
+		irq, gsi, vector, ioapic, ioapic_pin, trigger, polarity);
+
+	setup_ioapic_entry(ioapic, -1, &entry, ~0, trigger, polarity, vector);
+	ioapic_write_entry(ioapic, ioapic_pin, entry);
+}
+
 int xen_register_gsi(u32 gsi, int triggering, int polarity)
 {
 	int irq;
@@ -25,6 +52,11 @@ int xen_register_gsi(u32 gsi, int triggering, int polarity)
 
 	printk(KERN_DEBUG "xen: --> irq=%d\n", irq);
 
+	if (irq > 0)
+		xen_set_io_apic_routing(irq,
+					triggering == ACPI_EDGE_SENSITIVE ? 0 : 1,
+					polarity == ACPI_ACTIVE_HIGH ? 0 : 1);
+
 	return irq;
 }
 
-- 
1.6.0.6