fixup: riscv: use result for CSR enum conversion

Uses the crate result type for converting a CSR enum type from a
`usize`.

Author: rmsyn

riscv/src/register/macros.rs

@@ -666,10 +666,10 @@ macro_rules! csr_field_enum {
              }
 
              /// Attempts to convert a [`usize`] into a valid variant.
-             pub const fn from_usize(val: usize) -> Option<Self> {
+             pub const fn from_usize(val: usize) -> $crate::result::Result<Self> {
                  match val {
-                     $($value => Some(Self::$variant),)+
-                     _ => None,
+                     $($value => Ok(Self::$variant),)+
+                     _ => Err($crate::result::Error::InvalidVariant(val)),
                  }
              }
 
@@ -1036,10 +1036,7 @@ macro_rules! read_only_csr_field {
                          $field_end - $field_start + 1,
                      );
 
-                     $field_ty::from_usize(value).ok_or($crate::result::Error::InvalidFieldVariant {
-                         field: stringify!($field),
-                         value,
-                     })
+                     $field_ty::from_usize(value)
                  } else {
                     Err($crate::result::Error::IndexOutOfBounds {
                         index: $field_start,

riscv/src/register/tests/read_only_csr.rs

@@ -114,13 +114,7 @@ fn test_mtest_read_only() {
     assert_eq!(mtest.multi_field(), 0x0);
     assert_eq!(mtest.try_multi_field(), Ok(0x0));
 
-    assert_eq!(
-        mtest.try_field_enum(),
-        Err(Error::InvalidFieldVariant {
-            field: "field_enum",
-            value: 0,
-        })
-    );
+    assert_eq!(mtest.try_field_enum(), Err(Error::InvalidVariant(0)),);
 
     [
         MtestFieldEnum::Field1,
@@ -137,11 +131,5 @@ fn test_mtest_read_only() {
 
     // check that setting an invalid variant returns `None`
     mtest = Mtest::from_bits(0xbad << 7);
-    assert_eq!(
-        mtest.try_field_enum(),
-        Err(Error::InvalidFieldVariant {
-            field: "field_enum",
-            value: 13,
-        })
-    );
+    assert_eq!(mtest.try_field_enum(), Err(Error::InvalidVariant(13)),);
 }

riscv/src/register/tests/read_write_csr.rs

@@ -135,13 +135,7 @@ fn test_mtest_read_write() {
     assert_eq!(mtest.multi_field(), 0x0);
     assert_eq!(mtest.try_multi_field(), Ok(0x0));
 
-    assert_eq!(
-        mtest.try_field_enum(),
-        Err(Error::InvalidFieldVariant {
-            field: "field_enum",
-            value: 0,
-        })
-    );
+    assert_eq!(mtest.try_field_enum(), Err(Error::InvalidVariant(0)),);
 
     [
         MtestFieldEnum::Field1,
@@ -158,11 +152,5 @@ fn test_mtest_read_write() {
 
     // check that setting an invalid variant returns `None`
     mtest = Mtest::from_bits(0xbad << 7);
-    assert_eq!(
-        mtest.try_field_enum(),
-        Err(Error::InvalidFieldVariant {
-            field: "field_enum",
-            value: 13,
-        })
-    );
+    assert_eq!(mtest.try_field_enum(), Err(Error::InvalidVariant(13)),);
 }

riscv/src/register/tests/write_only_csr.rs

@@ -1,4 +1,4 @@
-use crate::result::Result;
+use crate::result::{Error, Result};
 
 write_only_csr! {
     /// test CSR register type
@@ -100,7 +100,10 @@ fn test_mtest_write_only() {
 
     mtest = Mtest::from_bits(0);
 
-    assert_eq!(MtestFieldEnum::from_usize(mtest.bits() >> 8), None);
+    assert_eq!(
+        MtestFieldEnum::from_usize(mtest.bits() >> 8),
+        Err(Error::InvalidVariant(0))
+    );
 
     [
         MtestFieldEnum::Field1,
@@ -116,10 +119,13 @@ fn test_mtest_write_only() {
             "field value: {variant:?}"
         );
         mtest.set_field_enum(variant);
-        assert_eq!(MtestFieldEnum::from_usize(mtest.bits() >> 8), Some(variant));
+        assert_eq!(MtestFieldEnum::from_usize(mtest.bits() >> 8), Ok(variant));
     });
 
     // check that setting an invalid variant returns `None`
     mtest = Mtest::from_bits(0xbad << 8);
-    assert_eq!(MtestFieldEnum::from_usize(mtest.bits() >> 8), None);
+    assert_eq!(
+        MtestFieldEnum::from_usize(mtest.bits() >> 8),
+        Err(Error::InvalidVariant(13))
+    );
 }