kern/amd64: Add interrupt registration framework

This commit introduces the interrupt registration framework for L5 and
accounts for I/O APIC IRQ inputs, and interrupt priority levels encoded
within bits 7:4 of the interrupt vector

Signed-off-by: Ian Moffett <ian@osmora.org>

2 files changed, 168 insertions, 0 deletions

diff --git a/src/sys/arch/amd64/mainbus/intr.c b/src/sys/arch/amd64/mainbus/intr.c
new file mode 100644
index 0000000..01d4f54
--- /dev/null
+++ b/src/sys/arch/amd64/mainbus/intr.c
@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * Description: Interrupt registration core
+ * Author: Ian Marco Moffett
+ */
+
+#include <sys/types.h>
+#include <machine/intr.h>
+#include <machine/ioapic.h>
+#include <os/kalloc.h>
+#include <string.h>
+
+/* List of interrupt handlers */
+static struct intr_hand *intrs[256] = {0};
+
+struct intr_hand *
+intr_register(const struct intr_hand *ih)
+{
+    struct intr_hand *ih_new = NULL;
+    int gsi;
+    uint8_t vec;
+
+    if (ih == NULL) {
+        return NULL;
+    }
+
+    /* Allocate a new interrupt handler */
+    ih_new = kalloc(sizeof(*ih_new));
+    if (ih_new == NULL) {
+        return NULL;
+    }
+
+    vec = MAX(ih->ipl << IPL_SHIFT, 0x20);
+
+    /*
+     * We can have up to 15 interrupt vectors per
+     * priority level as only 4 bits encode the IPL
+     */
+    for (int i = vec; i < vec + 16; ++i) {
+        if (intrs[i] != NULL) {
+            continue;
+        }
+
+        ih_new->name = strdup(ih->name);
+        ih_new->ipl = ih->ipl;
+        ih_new->irq = ih->irq;
+        ih_new->count = ih->count;
+        ih_new->vector = i;
+        intrs[i] = ih_new;
+
+        if (ih->irq >= 0) {
+            ioapic_route_vec(ih->irq, ih_new->vector);
+            gsi = ioapic_get_gsi(ih->irq);
+            ioapic_gsi_mask(gsi, 0);
+        }
+        return ih_new;
+
+    }
+
+    return NULL;
+}
diff --git a/src/sys/include/arch/amd64/intr.h b/src/sys/include/arch/amd64/intr.h
new file mode 100644
index 0000000..184d6d5
--- /dev/null
+++ b/src/sys/include/arch/amd64/intr.h
@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _MACHINE_INTR_H_
+#define _MACHINE_INTR_H_ 1
+
+#include <sys/types.h>
+
+#define IPL_NONE    0x00
+
+/* Upper 4 bits of an interrupt vector */
+#define IPL_SHIFT 4
+
+/*
+ * Represents an interrupt handler, this is split up into
+ * two parts. One side is only meant for the driver and C
+ * interrupt code to see, and the other shall be visible
+ * for the lower level interrupt handling code in vector.S
+ *
+ * @hand: Driver-specific handler to invoke [D]
+ * --
+ * @name: Name of interrupt         : strdup()'d  [D]
+ * @ipl: Interrupt priority level [D]
+ * @irq: IRQ number to use [D]
+ * @vector: Interrupt vector result [I]
+ * @count: Interrupt count [I]
+ *
+ * [D]: Set by driver
+ * [I]: Set internally
+ */
+struct intr_hand {
+    /* -- shared between vector.S -- */
+    int(*hand)(struct intr_hand *hp);
+
+    /* -- private to driver and C -- */
+    char *name;
+    int8_t ipl;
+    uint8_t irq;
+    uint8_t vector;
+    uint32_t count;
+};
+
+/*
+ * Register an interrupt with a specific priority
+ *
+ * @ih: Interrupt handler to register
+ *
+ * Returns new interrupt handler on success,
+ * otherwise NULL on failure
+ */
+struct intr_hand *intr_register(const struct intr_hand *ih);
+
+#endif  /* !_MACHINE_INTR_H_ */