sp1: mu: Add memory mapped I/O helpers

Signed-off-by: Chloe M. <chloe@mirocom.org>

usr/src/sp1/head/mu/mmio.h

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2026, Mirocom Laboratories
+ * All rights reserved.
+ *
+ * The following sources are CONFIDENTIAL and PROPRIETARY
+ * property of Mirocom Laboratories. Unauthorized copying,
+ * use, distribution or modification of this file, in whole
+ * and in part, is strictly prohibited without the prior written
+ * consent from Mirocom Laboratories.
+ */
+
+#ifndef _MU_MMIO_H_
+#define _MU_MMIO_H_ 1
+
+#include <sys/cdefs.h>
+
+/* Builds mmio_write<n> functions */
+#define _MMIO_WRITE_BUILDER(NAME, TYPE)     \
+    static inline void                      \
+    mmio_##NAME(TYPE *ptr, TYPE val)        \
+    {                                       \
+        __barrier();                        \
+        *(volatile TYPE *)ptr = val;        \
+    }
+
+/* Builds mmio_read<n> functions */
+#define _MMIO_READ_BUILDER(NAME, TYPE)      \
+    static inline TYPE                      \
+    mmio_##NAME(TYPE *ptr)                  \
+    {                                       \
+        __barrier();                        \
+        return *(volatile TYPE *)ptr;       \
+    }
+
+/* mmio_write<n> */
+_MMIO_WRITE_BUILDER(write8, uint8_t);
+_MMIO_WRITE_BUILDER(write16, uint16_t);
+_MMIO_WRITE_BUILDER(write32, uint32_t);
+#if __SIZEOF_SIZE_T__ == 8
+_MMIO_WRITE_BUILDER(write64, uint64_t);
+#endif
+
+/* Builds mmio_read<n> functions */
+_MMIO_READ_BUILDER(read8, uint8_t);
+_MMIO_READ_BUILDER(read16, uint16_t);
+_MMIO_READ_BUILDER(read32, uint32_t);
+#if __SIZEOF_SIZE_T__ == 8
+_MMIO_READ_BUILDER(read64, uint64_t);
+#endif
+
+#endif  /* !_MU_MMIO_H_ */