kern: Add initial scheduler skeleton

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

5 files changed, 228 insertions, 0 deletions

diff --git a/src/sys/include/os/sched.h b/src/sys/include/os/sched.h
new file mode 100644
index 0000000..b393395
--- /dev/null
+++ b/src/sys/include/os/sched.h
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * 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 the project 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 _OS_SCHED_H_
+#define _OS_SCHED_H_ 1
+
+#include <sys/types.h>
+#include <sys/queue.h>
+#include <sys/proc.h>
+#include <os/spinlock.h>
+
+#define SCHED_NQUEUES 4
+
+/*
+ * Represents a queue of processes
+ *
+ * @q; Actual queue
+ * @nproc: Number of processes in this queue
+ */
+struct sched_queue {
+    TAILQ_HEAD(, proc) q;
+    struct spinlock lock;
+    size_t nproc;
+};
+
+/*
+ * Enqueue a new process to a queue
+ *
+ * @q: Queue to target
+ * @proc: Process to place in the queue
+ *
+ * Returns zero on success, otherwise a less than
+ * zero value to indicate failure.
+ */
+int sched_enq(struct sched_queue *q, struct proc *proc);
+
+/*
+ * Dequeue a process from a queue
+ *
+ * @q: Queue to dequeue from
+ * @procp: Result of new popped process is written here
+ *
+ * Returns zero on success, otherwise a less than zero
+ * value on failure.
+ */
+int sched_deq(struct sched_queue *q, struct proc **procp);
+
+/*
+ * Initialize the scheduler into a basic
+ * known state.
+ */
+void sched_init(void);
+
+#endif  /* !_OS_SCHED_H_ */
diff --git a/src/sys/include/sys/cpuvar.h b/src/sys/include/sys/cpuvar.h
index 7431ce4..754335d 100644
--- a/src/sys/include/sys/cpuvar.h
+++ b/src/sys/include/sys/cpuvar.h
@@ -32,6 +32,7 @@
 
 #include <sys/types.h>
 #if defined(_KERNEL)
+#include <os/sched.h>
 #include <machine/mdcpu.h>
 #endif  /* _KERNEL */
 
@@ -41,12 +42,14 @@
  * independent.
  *
  * @id: Monotonic logical ID
+ * @scq: Scheduler queue
  * @md: Machine dependent processor information
  * @self: Chain pointer to self
  */
 struct pcore {
     uint32_t id;
 #if defined(_KERNEL)
+    struct sched_queue scq;
     struct mdcore md;
 #endif  /* _KERNEL */
     struct pcore *self;
diff --git a/src/sys/include/sys/proc.h b/src/sys/include/sys/proc.h
new file mode 100644
index 0000000..ab112cc
--- /dev/null
+++ b/src/sys/include/sys/proc.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * 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 the project 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 _SYS_PROC_H_
+#define _SYS_PROC_H_
+
+#include <sys/types.h>
+#include <sys/queue.h>
+
+/*
+ * A process describes a running program image
+ * on the system.
+ *
+ * @pid: Process ID
+ */
+struct proc {
+    pid_t pid;
+    TAILQ_ENTRY(proc) link;
+};
+
+#endif  /* !_SYS_PROC_H_ */
diff --git a/src/sys/os/os_init.c b/src/sys/os/os_init.c
index 00f5ffe..375649a 100644
--- a/src/sys/os/os_init.c
+++ b/src/sys/os/os_init.c
@@ -2,6 +2,7 @@
 #include <sys/panic.h>
 #include <sys/syslog.h>
 #include <sys/cpuvar.h>
+#include <os/sched.h>
 #include <acpi/acpi.h>
 #include <io/cons/cons.h>
 #include <vm/vm.h>
@@ -24,6 +25,7 @@ main(void)
     vm_init();
 
     cpu_init(&g_bsp);
+    sched_init();
     panic("end of kernel reached\n");
     for (;;);
 }
diff --git a/src/sys/os/os_sched.c b/src/sys/os/os_sched.c
new file mode 100644
index 0000000..f1bcc8c
--- /dev/null
+++ b/src/sys/os/os_sched.c
@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * 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 the project 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: Lunos scheduler core
+ * Author: Ian Marco Moffett
+ */
+
+#include <sys/types.h>
+#include <sys/errno.h>
+#include <sys/syslog.h>
+#include <sys/panic.h>
+#include <sys/queue.h>
+#include <sys/cpuvar.h>
+#include <os/sched.h>
+
+/*
+ * Enqueue a process into a queue
+ */
+int
+sched_enq(struct sched_queue *q, struct proc *proc)
+{
+    if (q == NULL || proc == NULL) {
+        return -EINVAL;
+    }
+
+    spinlock_acquire(&q->lock);
+    TAILQ_INSERT_TAIL(&q->q, proc, link);
+    ++q->nproc;
+    spinlock_release(&q->lock);
+    return 0;
+}
+
+/*
+ * Dequeue a process from a queue
+ */
+int
+sched_deq(struct sched_queue *q, struct proc **procp)
+{
+    struct proc *proc;
+
+    if (q == NULL || procp == NULL) {
+        return -EINVAL;
+    }
+
+    /* Anything to dequeue? */
+    if (q->nproc == 0) {
+        return -EAGAIN;
+    }
+
+    spinlock_acquire(&q->lock);
+    proc = TAILQ_FIRST(&q->q);
+    TAILQ_REMOVE(&q->q, proc, link);
+    --q->nproc;
+    spinlock_release(&q->lock);
+    return 0;
+}
+
+void
+sched_init(void)
+{
+    struct pcore *core;
+
+    if ((core = this_core()) == NULL) {
+        panic("sched_init: could not get core\n");
+    }
+
+    TAILQ_INIT(&core->scq.q);
+    printf("sched: scheduler is [up]\n");
+}