[ot] hw/opentitan: ot_common: Add register span macros

Adds macros for generic computing of the size of register spans for
OpenTitan multi registers, which can be used to e.g. make static
assertions to ensure that the size of macros matches the size of
buffers being used.

Co-authored-by: Emmanuel Blot <[email protected]>
Signed-off-by: Alex Jones <[email protected]>

Author: AlexJones0

include/hw/opentitan/ot_common.h

@@ -43,6 +43,15 @@
 #define OT_TL_UL_D_WIDTH_BITS  32u
 #define OT_TL_UL_D_WIDTH_BYTES ((OT_TL_UL_D_WIDTH_BITS) / 8u)
 
+/* ------------------------------------------------------------------------ */
+/* Register Span Definitions */
+/* ------------------------------------------------------------------------ */
+
+#define OT_REG_NAME_IDX(_n_, _i_) (R_##_n_##_##_i_)
+#define OT_REG_COUNT(_n_, _l_) \
+    (OT_REG_NAME_IDX(_n_, _l_) - OT_REG_NAME_IDX(_n_, 0) + 1u)
+#define OT_REG_SPAN(_n_, _l_) (OT_REG_COUNT(_n_, _l_) * sizeof(uint32_t))
+
 /* ------------------------------------------------------------------------ */
 /* Multi-bit boolean values */
 /* ------------------------------------------------------------------------ */