We had various deficiencies around sharing and overriding reset value…

…s on

registers that share types. This provides the groundwork for better functioning
here and provides error messages when the user asks for something we don't support.
We also added new reset_0s and reset_1s functions to all register types so long
as they don't have enumerated types. This provides some additional easy knobs to
get alternate reset values for your register types.

tools/site_cobble/rdl_pkg/listeners.py

@@ -78,6 +78,7 @@ class BaseListener(RDLListener):
     def __init__(self):
         self.prefix_stack = []
         self.known_types = []
+        self.reset_byte_known_type = {}
         self.cur_reg = None
         self.registers = []
 
@@ -136,6 +137,31 @@ def exit_Reg(self, node):
         # print(f"Exit reg: {node.inst_name}")
         self.cur_reg.elaborate()
         self.registers.append(self.cur_reg)
+        # If not a repeated type, put the reset value which we now know into a dictionary lookup
+        if not self.cur_reg.repeated_type:
+            self.reset_byte_known_type[self.cur_reg.type_name] = self.cur_reg.elaborated_reset, self.cur_reg.prefixed_name
+        else:
+            # If it was a repeated type, check that the reset value here matches the default reset value
+            base_reset, base_name = self.reset_byte_known_type.get(self.cur_reg.type_name)
+            reg_reset = self.cur_reg.elaborated_reset
+
+            # base reset is None, we'll allow 1s or 0s, nothing else. Anything else is an error
+            if base_reset is None and not (self.cur_reg.reset_is_all_1s or self.cur_reg.reset_is_all_0s):
+                raise ValueError(
+                   f"Reset value '{reg_reset}'for register {self.cur_reg.prefixed_name} is not all 1s or all 0s, "
+                   "and there's no default reset value for the type. The RDL subsystem doesn't support this pattern. "
+                   "Please check that you can't use a default value for the type, or elide the special reset value"
+                   " from the RDL and implement it in your own logic. You may also file an enhancement request to "
+                   "figure out how to better support this pattern."
+                )
+            elif reg_reset != base_reset and base_reset is not None:
+                raise ValueError(
+                   f"Reset value '{reg_reset}' for register {self.cur_reg.prefixed_name} does not match reset value '{base_reset}'"
+                   f" already defined for that type: {base_name}.\n"
+                   "This is likely due to a reset value override on an instance of the type that is conflicting "
+                   f"with a default value on the shared type '{self.cur_reg.type_name}'"
+
+                )
         self.cur_reg = None
 
     def enter_Field(self, node) -> None:

tools/site_cobble/rdl_pkg/models.py

@@ -20,8 +20,8 @@ class DuplicateEnumNameError(Exception):
 
 class BaseModel:
     @classmethod
-    def from_node(cls, node: RegNode, prefix_stack, repeated_type=False):
-        return cls(node=node, prefix_stack=prefix_stack, repeated_type=repeated_type)
+    def from_node(cls, node: RegNode, prefix_stack, repeated_type=False, base_reset=None):
+        return cls(node=node, prefix_stack=prefix_stack, repeated_type=repeated_type, base_reset=base_reset)
 
     def __init__(self, **kwargs):
         self.prefix = copy.deepcopy(kwargs.pop("prefix_stack"))
@@ -127,11 +127,42 @@ def encoded_fields(self):
         Returns any register fields that have encodings
         """
         return [x for x in self.packed_fields if x.has_encode()]
+
+    @property
+    def has_encoded_fields(self):
+        return len(self.encoded_fields) > 0
+
+    @property
+    def reset_is_all_1s(self):
+        for field in self.fields:
+            if (field.get_property("reset") is not None) and (not isinstance(field, ReservedField)):
+                expected_if_all_1s = 1 << (field.high - field.low + 1)
+                print(field.get_property("reset"), field.reset_1s)
+                if field.get_property("reset") != field.reset_1s:
+                    return False
+        return True
+
+    @property
+    def reset_is_all_0s(self):
+        return self.elaborated_reset == 0
+
+    @property
+    def elaborated_reset(self):
+        """
+        Returns the combined reset value of the register post elaboration, if it has one.
+        """
+        if not self.has_reset_definition:
+            return None
+        reset_val = 0
+        for field in self.fields:
+            if (field.get_property("reset") is not None) and (not isinstance(field, ReservedField)):
+                reset_val |= field.get_property("reset") << field.low
+        return reset_val
 
     @property
     def has_reset_definition(self):
         """
-        RDS doesn't force a reset definition on registers but we may want to conditionally generate
+        RDL doesn't force a reset definition on registers but we may want to conditionally generate
         reset logic if a reset value was specified.
         """
         # Get the reset value for all the fields. If we don't see None in any of them we have defined reset behavior
@@ -225,20 +256,44 @@ def get_property(self, *args, **kwargs):
         return prop
 
     @property
-    def reset_str(self):
+    def reset_str(self) -> str:
         my_rst = self.node.get_property("reset")
         return "{:#0x}".format(my_rst) if my_rst is not None else "None"
 
     @property
-    def vhdl_reset_or_default(self):
+    def vhdl_reset_or_default(self) -> str:
         my_rst = self.node.get_property("reset")
         reset_val = 0 if my_rst is None else my_rst
         if self.width > 1:
             return f'{self.width}x"{reset_val:X}"'
         else:
             return f"'{reset_val:1X}'"
+
+    @property
+    def reset_1s(self) -> int:
+        if self.width > 1:   
+            return (1 << self.width) - 1
+        else:
+            return 1
+
+    @property
+    def vhdl_reset_1s(self) -> str:
+        if self.width > 1:
+            reset_val = (1 << self.width) - 1
+            return f'{self.width}x"{reset_val:X}"'
+        else:
+            reset_val = 1
+            return f"'{reset_val:1X}'"
+
+    @property
+    def vhdl_reset_0s(self) -> str:
+        reset_val = 0
+        if self.width > 1:
+            return f'{self.width}x"{reset_val:X}"'
+        else:
+            return f"'{reset_val:1X}'"
 
-    def has_encode(self):
+    def has_encode(self) -> bool:
         return False
 
     def __str__(self):

tools/site_cobble/rdl_pkg/templates/regpkg_vhdl.jinja2

@@ -22,6 +22,10 @@
 --   sizeof() returns an integer of the number of used bits in the register
 --   rec_reset abusing overload signatures to return the reset value for the
 --     register type as defined in the RDL
+--   reset_1s abusing overload signatures to return the reset value for the
+--     register type with all defined bits set to 1
+--   reset_0s abusing overload signatures to return the reset value for the
+--     register type as defined bits set to 0
 --   "or","and", "xor" we provide overloads for logical bitwise functions for 
 --     the record type with itself on both sides, it on the left side with an 
 --     slv on the right, and it on the left side with an unsigned on the right.
@@ -102,7 +106,15 @@ package {{module_name}} is
   function compress (rec : {{reg_type_name}}) return std_logic_vector;
   function uncompress (vec : std_logic_vector) return {{reg_type_name}};
   function sizeof (rec : {{reg_type_name}}) return integer;
+  {# Only generate rec_reset if resets were specified #}
+  {% if register.has_reset_definition %}
   function rec_reset return {{reg_type_name}};
+  {% endif %}
+  {# We can only generate reset1's and reset0's for non-enumerated types #}
+  {% if not register.has_encoded_fields %}
+  function reset_1s return {{reg_type_name}};
+  function reset_0s return {{reg_type_name}};
+  {% endif %}
   function "or"  (left, right : {{reg_type_name}}) return {{reg_type_name}};
   function "or"  (left : {{reg_type_name}}; right : std_logic_vector) return {{reg_type_name}};
   function "or"  (left : {{reg_type_name}}; right : unsigned) return {{reg_type_name}};
@@ -227,6 +239,8 @@ package body {{module_name}} is
     begin
         return {{register.used_bits}};
     end sizeof;
+    {# Only generate rec_reset if resets were specified #}
+    {% if register.has_reset_definition %}
     function rec_reset return {{reg_type_name}} is
         variable ret_rec : {{reg_type_name}};
     begin
@@ -239,6 +253,26 @@ package body {{module_name}} is
         {% endfor %}
         return ret_rec;
     end rec_reset;
+    {% endif %}
+    {# We can only generate reset1's and reset0's for non-enumerated types #}
+    {% if not register.has_encoded_fields %}
+    function reset_1s return {{reg_type_name}} is
+        variable ret_rec : {{reg_type_name}};
+      begin
+        {% for field in register.packed_fields %}
+        ret_rec.{{field.name}} := {{field.vhdl_reset_1s}};
+        {% endfor %}
+        return ret_rec;
+    end reset_1s;
+    function reset_0s return {{reg_type_name}} is
+        variable ret_rec : {{reg_type_name}};
+      begin
+        {% for field in register.packed_fields %}
+        ret_rec.{{field.name}} := {{field.vhdl_reset_0s}};
+        {% endfor %}
+        return ret_rec;
+    end reset_0s;
+    {% endif %}
     function "or" (left, right : {{reg_type_name}}) return {{reg_type_name}} is
       variable ret_rec : {{reg_type_name}};
     begin