include: lib: add a simple singly linked list implementation

Add a simple singly linked list implementation when double linked list
are not needed. This allows to easily have statically defined linked
list that can be extended at runtime.

Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

include/sbi/sbi_slist.h

@@ -0,0 +1,33 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Simple simply-linked list library.
+ *
+ * Copyright (c) 2025 Rivos Inc.
+ *
+ * Authors:
+ *   Clément Léger <cleger@rivosinc.com>
+ */
+
+#ifndef __SBI_SLIST_H__
+#define __SBI_SLIST_H__
+
+#include <sbi/sbi_types.h>
+
+#define SBI_SLIST_HEAD_INIT(_ptr)	(_ptr)
+#define SBI_SLIST_HEAD(_lname, _stype) struct _stype *_lname
+#define SBI_SLIST_NODE(_stype) SBI_SLIST_HEAD(next, _stype)
+#define SBI_SLIST_NODE_INIT(_ptr) .next = _ptr
+
+#define SBI_INIT_SLIST_HEAD(_head) (_head) = NULL
+
+#define SBI_SLIST_ADD(_ptr, _head) \
+do { \
+	(_ptr)->next = _head; \
+	(_head) = _ptr; \
+} while (0)
+
+#define SBI_SLIST_FOR_EACH_ENTRY(_ptr, _head) \
+	for (_ptr = _head; _ptr; _ptr = _ptr->next)
+
+#endif