From b5c2ba80f70ce4dafdc32e326124fda6de0ef428 Mon Sep 17 00:00:00 2001
From: "Chloe M." <chloe@mensia.org>
Date: Tue, 23 Jun 2026 22:20:11 +0000
Subject: [PATCH] stos: ke: Add initial support for spinlocks

Signed-off-by: Chloe M. <chloe@mensia.org>
---
 paw/stos/head/ke/spinlock.h  | 48 +++++++++++++++++++++++++++++++++
 paw/stos/ke/Makefile         |  1 +
 paw/stos/ke/synch/spinlock.c | 52 ++++++++++++++++++++++++++++++++++++
 3 files changed, 101 insertions(+)
 create mode 100644 paw/stos/head/ke/spinlock.h
 create mode 100644 paw/stos/ke/synch/spinlock.c

diff --git a/paw/stos/head/ke/spinlock.h b/paw/stos/head/ke/spinlock.h
new file mode 100644
index 0000000..061a088
--- /dev/null
+++ b/paw/stos/head/ke/spinlock.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description:  Spinlock primitive
+ * Author:       Chloe M.
+ */
+
+#ifndef _KE_SPINLOCK_H_
+#define _KE_SPINLOCK_H_ 1
+
+#include <stdef.h>
+#include <hal/intr.h>
+
+/*
+ * Represents a spinlock that may be acquired for mutual
+ * exclusion of threads.
+ *
+ * @Data: Spinlock data (must be zero on init)
+ */
+typedef struct {
+    UQUAD Data;
+} SPINLOCK;
+
+/*
+ * Initialize a spinlock
+ *
+ * @Lock: Spinlock to initialize
+ * @Name: Name of spinlock
+ */
+VOID KeSpinLockInit(SPINLOCK *Lock, const CHAR *Name);
+
+/*
+ * Acquire a spinlock
+ *
+ * @Lock:   Lock to acquire
+ * @IrqMut: If true, mututate IRQ state upon acquisition
+ */
+VOID KeSpinLockAcquire(SPINLOCK *Lock, BOOLEAN IrqMut);
+
+/*
+ * Release a spinlock
+ *
+ * @Lock: Spinlock to release
+ */
+VOID KeSpinLockRelease(SPINLOCK *Lock);
+
+#endif  /* !_KE_SPINLOCK_H_ */
diff --git a/paw/stos/ke/Makefile b/paw/stos/ke/Makefile
index 2857632..df70295 100644
--- a/paw/stos/ke/Makefile
+++ b/paw/stos/ke/Makefile
@@ -17,6 +17,7 @@ CFILES += $(shell find ../drivers -name "*.c")
 CFILES += $(shell find ../mm -name "*.c")
 CFILES += $(shell find ../ex -name "*.c")
 CFILES += $(shell find bpal -name "*.c")
+CFILES += $(shell find synch -name "*.c")
 DFILES = $(CFILES:.c=.d)
 OFILES = $(CFILES:.c=.o)
 
diff --git a/paw/stos/ke/synch/spinlock.c b/paw/stos/ke/synch/spinlock.c
new file mode 100644
index 0000000..5f7ab35
--- /dev/null
+++ b/paw/stos/ke/synch/spinlock.c
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description:  Spinlock primitive
+ * Author:       Chloe M.
+ */
+
+#include <ke/spinlock.h>
+#include <hal/prim.h>
+
+VOID KeSpinLockInit(SPINLOCK *Lock, const CHAR *Name)
+{
+    if (Lock == NULL) {
+        return;
+    }
+
+    Lock->Data = 0;
+}
+
+VOID
+KeSpinLockAcquire(SPINLOCK *Lock, BOOLEAN IrqMut)
+{
+    IRQL LastIrql;
+
+    if (Lock == NULL) {
+        return;
+    }
+
+    if (IrqMut) {
+        LastIrql = HalRaiseIrql(IRQL_CRITICAL);
+    }
+
+    /* Acquire the lock */
+    while (HalCpuAswap(&Lock->Data, 1)) {
+        HalCpuSpinWait();
+    }
+
+    if (IrqMut) {
+        HalLowerIrql(LastIrql);
+    }
+}
+
+VOID
+KeSpinLockRelease(SPINLOCK *Lock)
+{
+    if (Lock == NULL) {
+        return;
+    }
+
+    HalCpuAswap(&Lock->Data, 0);
+}