From 3505969b3dffe2133d34c41076caa068ca2411b0 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Mon, 15 Sep 2025 11:46:39 -0400
Subject: kern/amd64: ioapic: Add IRQ to vector routing

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 src/sys/arch/amd64/mainbus/ioapic.c | 37 ++++++++++++++++++++++++++++++++++++-
 src/sys/include/arch/amd64/ioapic.h |  9 +++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/sys/arch/amd64/mainbus/ioapic.c b/src/sys/arch/amd64/mainbus/ioapic.c
index 360bd14..95ef55a 100644
--- a/src/sys/arch/amd64/mainbus/ioapic.c
+++ b/src/sys/arch/amd64/mainbus/ioapic.c
@@ -38,6 +38,7 @@
 
 static struct ioapic *ioapic = NULL;
 static struct acpi_madt *madt = NULL;
+static struct apic_header *override = NULL;
 
 /*
  * Write a single 32-bit value to a specific
@@ -181,6 +182,20 @@ __ioapic_callback(struct apic_header *hdr, size_t arg)
     return 0;
 }
 
+/*
+ * Convert an IRQ to a GSI
+ */
+static int
+__irq_to_gsi(struct apic_header *hdr, size_t irq)
+{
+    struct interrupt_override *override;
+
+    override = (struct interrupt_override *)hdr;
+    if (override->source == irq) {
+        return override->interrupt;
+    }
+
+    return -1;
 }
 
 /*
@@ -192,7 +207,27 @@ ioapic_gsi_mask(uint8_t gsi, uint8_t mask)
     union ioapic_redentry redent;
 
     ioapic_read_redentry(&redent, gsi);
-    redent.interrupt_mask = gsi & 1;
+    redent.interrupt_mask = mask & 1;
+    ioapic_write_redentry(&redent, gsi);
+}
+
+/*
+ * Map a GSI to a system interrupt vector
+ */
+void
+ioapic_route_vec(uint8_t irq, uint8_t vector)
+{
+    union ioapic_redentry redent;
+    int gsi;
+
+    gsi = ioapic_read_madt(
+        APIC_TYPE_INTERRUPT_OVERRIDE,
+        __irq_to_gsi,
+        irq
+    );
+
+    ioapic_read_redentry(&redent, gsi);
+    redent.vector = vector;
     ioapic_write_redentry(&redent, gsi);
 }
 
diff --git a/src/sys/include/arch/amd64/ioapic.h b/src/sys/include/arch/amd64/ioapic.h
index 9cd8bd4..20b8058 100644
--- a/src/sys/include/arch/amd64/ioapic.h
+++ b/src/sys/include/arch/amd64/ioapic.h
@@ -48,4 +48,13 @@ void ioapic_init(void);
  */
 void ioapic_gsi_mask(uint8_t gsi, uint8_t mask);
 
+/*
+ * Route an IRQ number to a system interrupt vector
+ * via the internal redirection table
+ *
+ * @irq: Global system interrupt to route
+ * @vector: Vector this GSI should map to
+ */
+void ioapic_route_vec(uint8_t irq, uint8_t vector);
+
 #endif  /* !_MACHINE_IOAPIC_H_ */
-- 
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