riscv: add raw bit access to generated CSR modules

riscv/CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Added
 
+- Add `read_bits`/`try_read_bits` and `write_bits`/`try_write_bits` to the CSR modules generated by `read_write_csr!` `read_only_csr!` and `write_only_csr!`.
 - Add `mireg` CSR
 - Add `stopei` and `vstopei` CSRs (AIA supervisor/virtual-supervisor top external
   interrupt), completing the `*topei` set alongside `mtopei`.

riscv/src/register/macros.rs

@@ -70,6 +70,17 @@ macro_rules! read_csr_as {
                 bits: unsafe { _read() },
             }
         }
+
+        /// Reads the raw bits of the CSR.
+        ///
+        /// Unlike [read], the value is not narrowed to the bitfields the
+        /// register type defines.
+        ///
+        /// **WARNING**: panics on non-`riscv` targets.
+        #[inline]
+        pub fn read_bits() -> usize {
+            unsafe { _read() }
+        }
     };
 
     ($register:ident, $csr_number:literal, $($cfg:meta),*) => {
@@ -82,6 +93,12 @@ macro_rules! read_csr_as {
                 bits: unsafe { _try_read()? },
             })
         }
+
+        /// Attempts to read the raw bits of the CSR.
+        #[inline]
+        pub fn try_read_bits() -> $crate::result::Result<usize> {
+            unsafe { _try_read() }
+        }
     };
 
     ($register:ident, $csr_number:literal, $sentinel:tt, $($cfg:meta),*) => {
@@ -95,6 +112,15 @@ macro_rules! read_csr_as {
                 bits => Ok($register { bits }),
             }
         }
+
+        /// Attempts to read the raw bits of the CSR.
+        #[inline]
+        pub fn try_read_bits() -> $crate::result::Result<usize> {
+            match unsafe { _try_read()? } {
+                $sentinel => Err($crate::result::Error::Unimplemented),
+                bits => Ok(bits),
+            }
+        }
     };
 }
 
@@ -214,6 +240,23 @@ macro_rules! write_csr_as {
         pub unsafe fn try_write(value: $csr_type) -> $crate::result::Result<()> {
             _try_write(value.bits)
         }
+
+        /// Writes raw bits to the CSR.
+        ///
+        /// Unlike [write()], the bits are not narrowed to the bitfields the
+        /// register type defines.
+        ///
+        /// **WARNING**: panics on non-`riscv` targets.
+        #[inline]
+        pub unsafe fn write_bits(bits: usize) {
+            _write(bits);
+        }
+
+        /// Attempts to write raw bits to the CSR.
+        #[inline]
+        pub unsafe fn try_write_bits(bits: usize) -> $crate::result::Result<()> {
+            _try_write(bits)
+        }
     };
     (safe $csr_type:ty, $csr_number:literal, $($cfg:meta),*) => {
         $crate::write_csr!($csr_number, $($cfg),*);
@@ -231,6 +274,23 @@ macro_rules! write_csr_as {
         pub fn try_write(value: $csr_type) -> $crate::result::Result<()> {
             unsafe { _try_write(value.bits) }
         }
+
+        /// Writes raw bits to the CSR.
+        ///
+        /// Unlike [write()], the bits are not narrowed to the bitfields the
+        /// register type defines.
+        ///
+        /// **WARNING**: panics on non-`riscv` targets.
+        #[inline]
+        pub fn write_bits(bits: usize) {
+            unsafe { _write(bits) }
+        }
+
+        /// Attempts to write raw bits to the CSR.
+        #[inline]
+        pub fn try_write_bits(bits: usize) -> $crate::result::Result<()> {
+            unsafe { _try_write(bits) }
+        }
     };
 }
 

riscv/src/register/tests/read_only_csr.rs

@@ -53,6 +53,21 @@ pub fn _try_read_csr() -> Result<Mtest> {
     try_read()
 }
 
+#[allow(unused)]
+pub fn _read_csr_bits() -> usize {
+    read_bits()
+}
+
+#[allow(unused)]
+pub fn _try_read_csr_bits() -> Result<usize> {
+    try_read_bits()
+}
+
+#[test]
+fn test_mtest_raw_bits() {
+    assert_eq!(try_read_bits(), Err(Error::Unimplemented));
+}
+
 #[test]
 fn test_mtest_read_only() {
     let mut mtest = Mtest::from_bits(0);

riscv/src/register/tests/read_write_csr.rs

@@ -63,6 +63,35 @@ pub fn _try_write_csr(csr: Mtest) {
     unsafe { try_write(csr) };
 }
 
+#[allow(unused)]
+pub fn _read_csr_bits() -> usize {
+    read_bits()
+}
+
+#[allow(unused)]
+pub fn _try_read_csr_bits() -> Result<usize> {
+    try_read_bits()
+}
+
+#[allow(unused)]
+pub fn _write_csr_bits(bits: usize) {
+    unsafe { write_bits(bits) };
+}
+
+#[allow(unused)]
+pub fn _try_write_csr_bits(bits: usize) -> Result<()> {
+    unsafe { try_write_bits(bits) }
+}
+
+#[test]
+fn test_mtest_raw_bits() {
+    assert_eq!(try_read_bits(), Err(Error::Unimplemented));
+    assert_eq!(
+        unsafe { try_write_bits(!Mtest::BITMASK) },
+        Err(Error::Unimplemented)
+    );
+}
+
 #[test]
 fn test_mtest_read_write() {
     let mut mtest = Mtest::from_bits(0);

riscv/src/register/tests/write_only_csr.rs

@@ -53,6 +53,24 @@ pub fn _try_write_csr(csr: Mtest) -> Result<()> {
     unsafe { try_write(csr) }
 }
 
+#[allow(unused)]
+pub fn _write_csr_bits(bits: usize) {
+    unsafe { write_bits(bits) };
+}
+
+#[allow(unused)]
+pub fn _try_write_csr_bits(bits: usize) -> Result<()> {
+    unsafe { try_write_bits(bits) }
+}
+
+#[test]
+fn test_mtest_raw_bits() {
+    assert_eq!(
+        unsafe { try_write_bits(!Mtest::BITMASK) },
+        Err(Error::Unimplemented)
+    );
+}
+
 #[test]
 fn test_mtest_write_only() {
     let mut mtest = Mtest::from_bits(0);