regtools: add register access to soc desc

Registers (and variants) can now specify the type of access supported:
- unspecified: for variant means same as register, for register defaults R/W
- read/write
- read only
- write only
Backward compatibility is preserved by setting access to unspecified by default.

Change-Id: I3e84ae18f962a45db62f996a542d08405d05b895

1 files changed, 23 insertions, 4 deletions

diff --git a/utils/regtools/include/soc_desc.hpp b/utils/regtools/include/soc_desc.hpp
index 66562f8..99f8706 100644
--- a/utils/regtools/include/soc_desc.hpp
+++ b/utils/regtools/include/soc_desc.hpp
@@ -77,6 +77,21 @@ protected:
  * Bare representation of the format
  */
 
+/** Register access type and rules
+ *
+ * Access can be specified on registers and register variants. When left
+ * unspecified (aka DEFAULT), a register variant inherit the access from
+ * the register, and a register defaults to read-write if unspecified.
+ * When specified, the register variant access takes precedence over the register
+ * access. */
+enum access_t
+{
+    UNSPECIFIED = 0, /** Register: read-write, fields: inherit from register */
+    READ_ONLY, /** Read-only */
+    READ_WRITE, /** Read-write */
+    WRITE_ONLY, /** Write-only */
+};
+
 /** Enumerated value (aka named value), represents a special value for a field */
 struct enum_t
 {
@@ -137,33 +152,37 @@ struct field_t
 /** Register variant information
  *
  * A register variant provides an alternative access to the register, potentially
- * we special semantics. Although there are no constraints on the type string,
+ * with special semantics. Although there are no constraints on the type string,
  * the following types have well-defined semantics:
  * - alias: the same register at another address
  * - set: writing to this register will set the 1s bits and ignore the 0s
  * - clr: writing to this register will clear the 1s bits and ignore the 0s
  * - tog: writing to this register will toggle the 1s bits and ignore the 0s
+ * Note that by default, variants inherit the access type of the register but
+ * can override it.
  */
 struct variant_t
 {
     soc_id_t id; /** ID (must be unique among register variants) */
     std::string type; /** type of the variant */
     soc_addr_t offset; /** offset of the variant */
+    access_t access; /** Access type */
 
-    /** Default constructor: default ID, offset is 0 */
-    variant_t():id(DEFAULT_ID), offset(0) {}
+    /** Default constructor: default ID, offset is 0, access is unspecified */
+    variant_t():id(DEFAULT_ID), offset(0), access(UNSPECIFIED) {}
 };
 
 /** Register information */
 struct register_t
 {
     size_t width; /** Size in bits */
+    access_t access; /** Access type */
     std::string desc; /** Optional description of the register */
     std::vector< field_t > field; /** List of fields */
     std::vector< variant_t > variant; /** List of variants */
 
     /** Default constructor: width is 32 */
-    register_t():width(32) {}
+    register_t():width(32), access(UNSPECIFIED) {}
 };
 
 /** Node address range information */