Commit 5981d03c authored by Zhi Wang's avatar Zhi Wang Committed by Danilo Krummrich
Browse files

rust: io: factor out MMIO read/write macros 



Refactor the existing MMIO accessors to use common call macros
instead of inlining the bindings calls in each `define_{read,write}!`
expansion.

This factoring separates the common offset/bounds checks from the
low-level call pattern, making it easier to add additional I/O accessor
families.

No functional change intended.

Cc: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: default avatarZhi Wang <zhiw@nvidia.com>
Reviewed-by: default avatarAlexandre Courbot <acourbot@nvidia.com>
Link: https://patch.msgid.link/20260121202212.4438-4-zhiw@nvidia.com


Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
parent 121d87b2

rust/kernel/io.rs

+102 −45
Original line number Diff line number Diff line
@@ -137,8 +137,65 @@ pub fn maxsize(&self) -> usize { 
#[repr(transparent)]

pub struct Mmio<const SIZE: usize = 0>(MmioRaw<SIZE>);



/// Internal helper macros used to invoke C MMIO read functions.

///

/// This macro is intended to be used by higher-level MMIO access macros (define_read) and provides

/// a unified expansion for infallible vs. fallible read semantics. It emits a direct call into the

/// corresponding C helper and performs the required cast to the Rust return type.

///

/// # Parameters

///

/// * `$c_fn` – The C function performing the MMIO read.

/// * `$self` – The I/O backend object.

/// * `$ty` – The type of the value to be read.

/// * `$addr` – The MMIO address to read.

///

/// This macro does not perform any validation; all invariants must be upheld by the higher-level

/// abstraction invoking it.

macro_rules! call_mmio_read {

    (infallible, $c_fn:ident, $self:ident, $type:ty, $addr:expr) => {

        // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.

        unsafe { bindings::$c_fn($addr as *const c_void) as $type }

    };



    (fallible, $c_fn:ident, $self:ident, $type:ty, $addr:expr) => {{

        // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.

        Ok(unsafe { bindings::$c_fn($addr as *const c_void) as $type })

    }};

}



/// Internal helper macros used to invoke C MMIO write functions.

///

/// This macro is intended to be used by higher-level MMIO access macros (define_write) and provides

/// a unified expansion for infallible vs. fallible write semantics. It emits a direct call into the

/// corresponding C helper and performs the required cast to the Rust return type.

///

/// # Parameters

///

/// * `$c_fn` – The C function performing the MMIO write.

/// * `$self` – The I/O backend object.

/// * `$ty` – The type of the written value.

/// * `$addr` – The MMIO address to write.

/// * `$value` – The value to write.

///

/// This macro does not perform any validation; all invariants must be upheld by the higher-level

/// abstraction invoking it.

macro_rules! call_mmio_write {

    (infallible, $c_fn:ident, $self:ident, $ty:ty, $addr:expr, $value:expr) => {

        // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.

        unsafe { bindings::$c_fn($value, $addr as *mut c_void) }

    };



    (fallible, $c_fn:ident, $self:ident, $ty:ty, $addr:expr, $value:expr) => {{

        // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.

        unsafe { bindings::$c_fn($value, $addr as *mut c_void) };

        Ok(())

    }};

}



macro_rules! define_read {

    (infallible, $(#[$attr:meta])* $vis:vis $name:ident, $c_fn:ident -> $type_name:ty) => {

    (infallible, $(#[$attr:meta])* $vis:vis $name:ident, $call_macro:ident($c_fn:ident) ->

     $type_name:ty) => {

        /// Read IO data from a given offset known at compile time.

        ///

        /// Bound checks are performed on compile time, hence if the offset is not known at compile
@@ -148,12 +205,13 @@ macro_rules! define_read { 
        $vis fn $name(&self, offset: usize) -> $type_name {

            let addr = self.io_addr_assert::<$type_name>(offset);



            // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.

            unsafe { bindings::$c_fn(addr as *const c_void) }

            // SAFETY: By the type invariant `addr` is a valid address for IO operations.

            $call_macro!(infallible, $c_fn, self, $type_name, addr)

        }

    };



    (fallible, $(#[$attr:meta])* $vis:vis $try_name:ident, $c_fn:ident -> $type_name:ty) => {

    (fallible, $(#[$attr:meta])* $vis:vis $try_name:ident, $call_macro:ident($c_fn:ident) ->

     $type_name:ty) => {

        /// Read IO data from a given offset.

        ///

        /// Bound checks are performed on runtime, it fails if the offset (plus the type size) is
@@ -162,8 +220,8 @@ macro_rules! define_read { 
        $vis fn $try_name(&self, offset: usize) -> Result<$type_name> {

            let addr = self.io_addr::<$type_name>(offset)?;



            // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.

            Ok(unsafe { bindings::$c_fn(addr as *const c_void) })

            // SAFETY: By the type invariant `addr` is a valid address for IO operations.

            $call_macro!(fallible, $c_fn, self, $type_name, addr)

        }

    };

}
@@ -171,7 +229,8 @@ macro_rules! define_read { 
pub(crate) use define_read;



macro_rules! define_write {

    (infallible, $(#[$attr:meta])* $vis:vis $name:ident, $c_fn:ident <- $type_name:ty) => {

    (infallible, $(#[$attr:meta])* $vis:vis $name:ident, $call_macro:ident($c_fn:ident) <-

     $type_name:ty) => {

        /// Write IO data from a given offset known at compile time.

        ///

        /// Bound checks are performed on compile time, hence if the offset is not known at compile
@@ -181,12 +240,12 @@ macro_rules! define_write { 
        $vis fn $name(&self, value: $type_name, offset: usize) {

            let addr = self.io_addr_assert::<$type_name>(offset);



            // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.

            unsafe { bindings::$c_fn(value, addr as *mut c_void) }

            $call_macro!(infallible, $c_fn, self, $type_name, addr, value);

        }

    };



    (fallible, $(#[$attr:meta])* $vis:vis $try_name:ident, $c_fn:ident <- $type_name:ty) => {

    (fallible, $(#[$attr:meta])* $vis:vis $try_name:ident, $call_macro:ident($c_fn:ident) <-

     $type_name:ty) => {

        /// Write IO data from a given offset.

        ///

        /// Bound checks are performed on runtime, it fails if the offset (plus the type size) is
@@ -195,9 +254,7 @@ macro_rules! define_write { 
        $vis fn $try_name(&self, value: $type_name, offset: usize) -> Result {

            let addr = self.io_addr::<$type_name>(offset)?;



            // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.

            unsafe { bindings::$c_fn(value, addr as *mut c_void) };

            Ok(())

            $call_macro!(fallible, $c_fn, self, $type_name, addr, value)

        }

    };

}
@@ -453,44 +510,44 @@ fn maxsize(&self) -> usize { 
        self.0.maxsize()

    }



    define_read!(fallible, try_read8, readb -> u8);

    define_read!(fallible, try_read16, readw -> u16);

    define_read!(fallible, try_read32, readl -> u32);

    define_read!(fallible, try_read8, call_mmio_read(readb) -> u8);

    define_read!(fallible, try_read16, call_mmio_read(readw) -> u16);

    define_read!(fallible, try_read32, call_mmio_read(readl) -> u32);

    define_read!(

        fallible,

        #[cfg(CONFIG_64BIT)]

        try_read64,

        readq -> u64

        call_mmio_read(readq) -> u64

    );



    define_write!(fallible, try_write8, writeb <- u8);

    define_write!(fallible, try_write16, writew <- u16);

    define_write!(fallible, try_write32, writel <- u32);

    define_write!(fallible, try_write8, call_mmio_write(writeb) <- u8);

    define_write!(fallible, try_write16, call_mmio_write(writew) <- u16);

    define_write!(fallible, try_write32, call_mmio_write(writel) <- u32);

    define_write!(

        fallible,

        #[cfg(CONFIG_64BIT)]

        try_write64,

        writeq <- u64

        call_mmio_write(writeq) <- u64

    );



    define_read!(infallible, read8, readb -> u8);

    define_read!(infallible, read16, readw -> u16);

    define_read!(infallible, read32, readl -> u32);

    define_read!(infallible, read8, call_mmio_read(readb) -> u8);

    define_read!(infallible, read16, call_mmio_read(readw) -> u16);

    define_read!(infallible, read32, call_mmio_read(readl) -> u32);

    define_read!(

        infallible,

        #[cfg(CONFIG_64BIT)]

        read64,

        readq -> u64

        call_mmio_read(readq) -> u64

    );



    define_write!(infallible, write8, writeb <- u8);

    define_write!(infallible, write16, writew <- u16);

    define_write!(infallible, write32, writel <- u32);

    define_write!(infallible, write8, call_mmio_write(writeb) <- u8);

    define_write!(infallible, write16, call_mmio_write(writew) <- u16);

    define_write!(infallible, write32, call_mmio_write(writel) <- u32);

    define_write!(

        infallible,

        #[cfg(CONFIG_64BIT)]

        write64,

        writeq <- u64

        call_mmio_write(writeq) <- u64

    );

}
@@ -508,43 +565,43 @@ pub unsafe fn from_raw(raw: &MmioRaw<SIZE>) -> &Self { 
        unsafe { &*core::ptr::from_ref(raw).cast() }

    }



    define_read!(infallible, pub read8_relaxed, readb_relaxed -> u8);

    define_read!(infallible, pub read16_relaxed, readw_relaxed -> u16);

    define_read!(infallible, pub read32_relaxed, readl_relaxed -> u32);

    define_read!(infallible, pub read8_relaxed, call_mmio_read(readb_relaxed) -> u8);

    define_read!(infallible, pub read16_relaxed, call_mmio_read(readw_relaxed) -> u16);

    define_read!(infallible, pub read32_relaxed, call_mmio_read(readl_relaxed) -> u32);

    define_read!(

        infallible,

        #[cfg(CONFIG_64BIT)]

        pub read64_relaxed,

        readq_relaxed -> u64

        call_mmio_read(readq_relaxed) -> u64

    );



    define_read!(fallible, pub try_read8_relaxed, readb_relaxed -> u8);

    define_read!(fallible, pub try_read16_relaxed, readw_relaxed -> u16);

    define_read!(fallible, pub try_read32_relaxed, readl_relaxed -> u32);

    define_read!(fallible, pub try_read8_relaxed, call_mmio_read(readb_relaxed) -> u8);

    define_read!(fallible, pub try_read16_relaxed, call_mmio_read(readw_relaxed) -> u16);

    define_read!(fallible, pub try_read32_relaxed, call_mmio_read(readl_relaxed) -> u32);

    define_read!(

        fallible,

        #[cfg(CONFIG_64BIT)]

        pub try_read64_relaxed,

        readq_relaxed -> u64

        call_mmio_read(readq_relaxed) -> u64

    );



    define_write!(infallible, pub write8_relaxed, writeb_relaxed <- u8);

    define_write!(infallible, pub write16_relaxed, writew_relaxed <- u16);

    define_write!(infallible, pub write32_relaxed, writel_relaxed <- u32);

    define_write!(infallible, pub write8_relaxed, call_mmio_write(writeb_relaxed) <- u8);

    define_write!(infallible, pub write16_relaxed, call_mmio_write(writew_relaxed) <- u16);

    define_write!(infallible, pub write32_relaxed, call_mmio_write(writel_relaxed) <- u32);

    define_write!(

        infallible,

        #[cfg(CONFIG_64BIT)]

        pub write64_relaxed,

        writeq_relaxed <- u64

        call_mmio_write(writeq_relaxed) <- u64

    );



    define_write!(fallible, pub try_write8_relaxed, writeb_relaxed <- u8);

    define_write!(fallible, pub try_write16_relaxed, writew_relaxed <- u16);

    define_write!(fallible, pub try_write32_relaxed, writel_relaxed <- u32);

    define_write!(fallible, pub try_write8_relaxed, call_mmio_write(writeb_relaxed) <- u8);

    define_write!(fallible, pub try_write16_relaxed, call_mmio_write(writew_relaxed) <- u16);

    define_write!(fallible, pub try_write32_relaxed, call_mmio_write(writel_relaxed) <- u32);

    define_write!(

        fallible,

        #[cfg(CONFIG_64BIT)]

        pub try_write64_relaxed,

        writeq_relaxed <- u64

        call_mmio_write(writeq_relaxed) <- u64

    );

}