Add some more parameters to reflects options in mstatus

arch/csr/mstatus.yaml

@@ -241,9 +241,29 @@ mstatus:
         *`hfence.vvma`, `sfence.w.inval`, or `sfence.inval.ir` to trap.
         * Any additional traps in VS-mode (controlled via `hstatus.VTVM` instead).
 
-      type: RW
+      type(): |
+        if (CSR[misa].S == 1'b0) {
+          return CsrFieldType::RO;
+        } else {
+          return CsrFieldType::RW;
+        }
       definedBy: S
-      reset_value: UNDEFINED_LEGAL
+      reset_value(): |
+        if (CSR[misa].S == 1'b0) {
+          return 0;
+        } else if (MSTATUS_TVM_IMPLEMENTED) {
+          return UNDEFINED_LEGAL;
+        } else {
+          return 0;
+        }
+      sw_write(csr_value): |
+        if (CSR[misa].S == 1'b0) {
+          return 0;
+        } else if (MSTATUS_TVM_IMPLEMENTED) {
+          return csr_value.TVM;
+        } else {
+          return 0;
+        }
     MXR:
       location: 19
       description: |
@@ -286,7 +306,8 @@ mstatus:
 
         `mstatus.MPRV` is cleared on any exception return (`mret` or `sret` instruction, regardless of the trap handler privilege mode).
       definedBy: U
-      type: RW-H
+      type(): |
+        return (CSR[misa].U == 1'b1) ? CsrFieldType::RWH : CsrFieldType::RO;
       reset_value: 0
     XS:
       location: 16-15
@@ -308,9 +329,40 @@ mstatus:
         When a floating point register, or the fCSR register is written, FS obtains the value 3.
         Values 1 and 2 are valid write values for software, but are not interpreted by hardware
         other than to possibly enable a previously-disabled floating point unit. 
-      type: RW-H
+      type(): |
+        if (CSR[misa].F == 1'b1){
+          return CsrFieldType::RWH;
+        } else if ((CSR[misa].S == 1'b0) && (CSR[misa].F == 1'b0)) {
+          # must be read-only-0
+          return CsrFieldType::RO;
+        } else {
+          assert (CSR[misa].S == 1'b1);
+          # there will be no hardware update in this case because we know the F extension isn't implemented
+          return MSTATUS_FS_WRITEABLE ? CsrFieldType::RW : CsrFieldType::RO;
+        }
       definedBy: F
-      reset_value: UNDEFINED_LEGAL
+      reset_value(): |
+        if (CSR[misa].F == 1'b1){
+          return UNDEFINED_LEGAL;
+        } else if ((CSR[misa].S == 1'b0) && (CSR[misa].F == 1'b0)) {
+          # must be read-only-0
+          return 0;
+        } else {
+          assert (CSR[misa].S == 1'b1);
+          # there will be no hardware update in this case because we know the F extension isn't implemented
+          return MSTATUS_FS_WRITEABLE ? UNDEFINED_LEGAL : 0;
+        }
+      sw_write(csr_value): |
+        if (CSR[misa].F == 1'b1){
+          return ary_includes?(MSTATUS_FS_LEGAL_VALUES, csr_value.FS) ? csr_value.FS : UNDEFINED_LEGAL_DETERMINISTIC;
+        } else if ((CSR[misa].S == 1'b0) && (CSR[misa].F == 1'b0)) {
+          # must be read-only-0
+          return 0;
+        } else {
+          assert (CSR[misa].S == 1'b1);
+          # there will be no hardware update in this case because we know the F extension isn't implemented
+          return ary_includes?(MSTATUS_FS_LEGAL_VALUES, csr_value.FS) ? csr_value.FS : UNDEFINED_LEGAL_DETERMINISTIC;
+        }
     MPP:
       location: 12-11
       description: |
@@ -449,9 +501,11 @@ mstatus:
         Can also be written by software without immediate side effect.
 
         Other than serving as a record of nested traps as described above, `mstatus.SPIE` does not affect execution.
-      type: RW-H
+      type(): |
+        return (CSR[misa].S == 1'b1) ? CsrFieldType::RWH : CsrFieldType::RO;
       definedBy: S
-      reset_value: UNDEFINED_LEGAL
+      reset_value(): |
+        return (CSR[misa].S == 1'b1) ? UNDEFINED_LEGAL : 0;
     MIE:
       location: 3
       description: |
@@ -484,6 +538,8 @@ mstatus:
         * When 0, all (H)S-mode interrupts are disabled when the current privilege level is (H)S (M-mode interrupts are still enabled).
         * When 1, (H)S-mode interrupts that are not otherwise disabled with a field in `sie` are enabled.
 
-      type: RW-H
+      type(): |
+        return (CSR[misa].S == 1'b1) ? CsrFieldType::RWH : CsrFieldType::RO;
       definedBy: S
-      reset_value: UNDEFINED_LEGAL
+      reset_value(): |
+        return (CSR[misa].S == 1'b1) ? UNDEFINED_LEGAL : 0;

arch/ext/F.yaml

@@ -238,4 +238,17 @@ F:
       description: |
         Indicates whether or not the `F` extension can be disabled with the `misa.F` bit.
       schema:
-        type: boolean
+        type: boolean
+    MSTATUS_FS_LEGAL_VALUES:
+      description: |
+        The set of values that mstatus.FS will accept from a software write.
+      schema:
+        type: array
+        items:
+          type: integer
+          enum: [0,1,2,3]
+        maxItems: 4
+        uniqueItems: true
+      also_defined_in: S
+      extra_validation: |
+        assert MSTATUS_FS_LEGAL_VALUES.include?(0) && MSTATUS_FS_LEGAL_VALUES.include?(3) if ext?(:F)

arch/ext/S.yaml

@@ -242,4 +242,33 @@ S:
         type: boolean
         default: false
       extra_validation:
-        assert TRAP_ON_SFENCE_VMA_WHEN_SATP_MODE_IS_READ_ONLY == false if ext?(:Sv32) || ext?(:Sv39) || ext?(:Sv48) || ext?(:Sv57)
+        assert TRAP_ON_SFENCE_VMA_WHEN_SATP_MODE_IS_READ_ONLY == false if ext?(:Sv32) || ext?(:Sv39) || ext?(:Sv48) || ext?(:Sv57)
+    MSTATUS_FS_WRITEABLE:
+      description: |
+        When `S` is enabled but `F` is not, mstatus.FS is optionally writeable.
+
+        This parameter only has an effect when both S and F mode are disabled.
+      schema:
+        type: boolean
+      extra_validation:
+        assert MSTATUS_FS_WRITEABL == true if ext?(:F)
+    MSTATUS_FS_LEGAL_VALUES:
+      description: |
+        The set of values that mstatus.FS will accept from a software write.
+      schema:
+        type: array
+        items:
+          type: integer
+          enum: [0,1,2,3]
+        maxItems: 4
+        uniqueItems: true
+      also_defined_in: F
+      extra_validation: |
+        assert MSTATUS_FS_LEGAL_VALUES.include?(0) && MSTATUS_FS_LEGAL_VALUES.include?(3) if ext?(:F)
+    MSTATUS_TVM_IMPLEMENTED:
+      description: |
+        Whether or not mstatus.TVM is implemented.
+
+        When not implemented mstatus.TVM will be read-only-zero.
+      schema:
+        type: boolean

lib/idl/type.rb

@@ -172,15 +172,17 @@ def equal_to?(type)
 
       case @kind
       when :boolean
-        return type.kind == :boolean
+        type.kind == :boolean
       when :enum_ref
-        return type.kind == :enum_ref && type.name == @enum_class.name
+        type.kind == :enum_ref && type.name == @enum_class.name
       when :dontcare
-        return true
+        true
       when :bits
-        return type.kind == :bits && type.width == @width
+        type.kind == :bits && type.width == @width
       when :string
-        return type.kind == :string && type.width == @width
+        type.kind == :string && type.width == @width
+      when :array
+        type.kind == :array && type.sub_type.equal_to?(@sub_type)
       else
         raise "unimplemented type '#{@kind}'"
       end