riscv-peripheral: const methods for HART 0

riscv-peripheral/CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+### Added
+
+- Constant methods to access to PLIC and ACLINT registers for HART 0.
+  These new methods are especially convenient for single-HART targets.
+
 ## [v0.3.0] - 2025-06-10
 
 ### Changed

riscv-peripheral/src/aclint.rs

@@ -130,6 +130,7 @@ pub(crate) mod test {
         assert_eq!(mtime.get_ptr() as usize, 0x0200_bff8);
 
         assert_eq!(clint.mtimecmp0(), mtimer.mtimecmp(HartId::H0));
+        assert_eq!(clint.mtimecmp0(), mtimer.mtimecmp0());
         assert_eq!(clint.mtimecmp1(), mtimer.mtimecmp(HartId::H1));
         assert_eq!(clint.mtimecmp2(), mtimer.mtimecmp(HartId::H2));
 

riscv-peripheral/src/aclint/mswi.rs

@@ -81,6 +81,19 @@ impl<M: Mswi> MSWI<M> {
         unsafe { MSIP::new(self.as_ptr().add(hart_id.number()) as _) }
     }
 
+    /// Returns the `MSIP` register for HART 0.
+    ///
+    /// # Note
+    ///
+    /// According to the RISC-V specification, HART 0 is mandatory.
+    /// Thus, this function is specially useful in single-HART mode, where HART 0 is the only HART available.
+    /// In multi-HART mode, it is recommended to use [`MSWI::msip`] or [`MSWI::msip_mhartid`] instead.
+    #[inline]
+    pub const fn msip0(self) -> MSIP {
+        // SAFETY: HART 0 is mandatory
+        unsafe { MSIP::new(M::BASE) }
+    }
+
     /// Returns the `MSIP` register for the current HART.
     ///
     /// # Note

riscv-peripheral/src/aclint/mtimer.rs

@@ -105,6 +105,19 @@ impl<M: Mtimer> MTIMER<M> {
         unsafe { MTIMECMP::new(self.mtimecmp_as_ptr().add(hart_id.number()) as _) }
     }
 
+    /// Returns the `MTIMECMP` register for HART 0.
+    ///
+    /// # Note
+    ///
+    /// According to the RISC-V specification, HART 0 is mandatory.
+    /// Thus, this function is specially useful in single-HART mode, where HART 0 is the only HART available.
+    /// In multi-HART mode, it is recommended to use [`MTIMER::mtimecmp`] or [`MTIMER::mtimecmp_mhartid`] instead.
+    #[inline]
+    pub const fn mtimecmp0(self) -> MTIMECMP {
+        // SAFETY: HART 0 is mandatory
+        unsafe { MTIMECMP::new(M::MTIMECMP_BASE) }
+    }
+
     /// Returns the `MTIMECMP` register for the current HART.
     ///
     /// # Note

riscv-peripheral/src/aclint/sswi.rs

@@ -71,6 +71,19 @@ impl<S: Sswi> SSWI<S> {
         // SAFETY: `hart_id` is valid for the target
         unsafe { SETSSIP::new(self.as_ptr().add(hart_id.number()) as _) }
     }
+
+    /// Returns the `SETSSIP` register for HART 0.
+    ///
+    /// # Note
+    ///
+    /// According to the RISC-V specification, HART 0 is mandatory.
+    /// Thus, this function is specially useful in single-HART mode, where HART 0 is the only HART available.
+    /// In multi-HART mode, it is recommended to use [`SSWI::setssip`] instead.
+    #[inline]
+    pub const fn setssip0(self) -> SETSSIP {
+        // SAFETY: HART 0 is mandatory
+        unsafe { SETSSIP::new(S::BASE) }
+    }
 }
 
 unsafe_peripheral!(SETSSIP, u32, RW);

riscv-peripheral/src/plic.rs

@@ -108,6 +108,19 @@ impl<P: Plic> PLIC<P> {
         unsafe { CTX::new(hart_id.number() as _) }
     }
 
+    /// Returns the PLIC HART context for HART 0.
+    ///
+    /// # Note
+    ///
+    /// According to the RISC-V specification, HART 0 is mandatory.
+    /// Thus, this function is specially useful in single-HART mode, where HART 0 is the only HART available.
+    /// In multi-HART mode, it is recommended to use [`PLIC::ctx`] or [`PLIC::ctx_mhartid`] instead.
+    #[inline]
+    pub const fn ctx0(self) -> CTX<P> {
+        // SAFETY: HART 0 is mandatory
+        unsafe { CTX::new(0) }
+    }
+
     /// Returns the PLIC HART context for the current HART.
     ///
     /// # Note
@@ -146,7 +159,7 @@ impl<P: Plic> CTX<P> {
     ///
     /// The context number must be valid for the target device.
     #[inline]
-    pub(crate) unsafe fn new(context: u16) -> Self {
+    const unsafe fn new(context: u16) -> Self {
         Self {
             context: context as _,
             _marker: core::marker::PhantomData,
@@ -195,8 +208,8 @@ pub(crate) mod test {
         crate::plic_codegen!(
             PLIC,
             base 0x0C00_0000,
-            harts [HartId::H0 => 0, HartId::H1 => 1, HartId::H2 => 2]
-        );
+            harts [HartId::H1 => 1, HartId::H2 => 2]
+        ); // We skip HART 0 to get advantage of const ctx0 method
 
         let plic = PLIC::new();
         let priorities = plic.priorities();