3 files changed, 288 insertions, 0 deletions
diff --git a/rust/kernel/soc/apple/mod.rs b/rust/kernel/soc/apple/mod.rs
new file mode 100644
index 000000000000..dd69db63677d
--- /dev/null
+++ b/rust/kernel/soc/apple/mod.rs
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+
+//! Apple SoC drivers
+
+#[cfg(CONFIG_APPLE_RTKIT = "y")]
+pub mod rtkit;
diff --git a/rust/kernel/soc/apple/rtkit.rs b/rust/kernel/soc/apple/rtkit.rs
new file mode 100644
index 000000000000..bde63cd00193
--- /dev/null
+++ b/rust/kernel/soc/apple/rtkit.rs
@@ -0,0 +1,277 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+
+//! Support for Apple RTKit coprocessors.
+//!
+//! C header: [`include/linux/soc/apple/rtkit.h`](../../../../include/linux/gpio/driver.h)
+
+use crate::{
+    bindings, device,
+    error::{code::*, from_kernel_err_ptr, to_result, Error, Result},
+    str::CStr,
+    types::{ForeignOwnable, ScopeGuard},
+};
+
+use alloc::boxed::Box;
+use core::marker::PhantomData;
+use core::ptr;
+use macros::vtable;
+
+/// Trait to represent allocatable buffers for the RTKit core.
+///
+/// Users must implement this trait for their own representation of those allocations.
+pub trait Buffer {
+    /// Returns the IOVA (virtual address) of the buffer from RTKit's point of view, or an error if
+    /// unavailable.
+    fn iova(&self) -> Result<usize>;
+
+    /// Returns a mutable byte slice of the buffer contents, or an
+    /// error if unavailable.
+    fn buf(&mut self) -> Result<&mut [u8]>;
+}
+
+/// Callback operations for an RTKit client.
+#[vtable]
+pub trait Operations {
+    /// Arbitrary user context type.
+    type Data: ForeignOwnable + Send + Sync;
+
+    /// Type representing an allocated buffer for RTKit.
+    type Buffer: Buffer;
+
+    /// Called when RTKit crashes.
+    fn crashed(_data: <Self::Data as ForeignOwnable>::Borrowed<'_>) {}
+
+    /// Called when a message was received on a non-system endpoint. Called in non-IRQ context.
+    fn recv_message(
+        _data: <Self::Data as ForeignOwnable>::Borrowed<'_>,
+        _endpoint: u8,
+        _message: u64,
+    ) {
+    }
+
+    /// Called in IRQ context when a message was received on a non-system endpoint.
+    ///
+    /// Must return `true` if the message is handled, or `false` to process it in
+    /// the handling thread.
+    fn recv_message_early(
+        _data: <Self::Data as ForeignOwnable>::Borrowed<'_>,
+        _endpoint: u8,
+        _message: u64,
+    ) -> bool {
+        false
+    }
+
+    /// Allocate a buffer for use by RTKit.
+    fn shmem_alloc(
+        _data: <Self::Data as ForeignOwnable>::Borrowed<'_>,
+        _size: usize,
+    ) -> Result<Self::Buffer> {
+        Err(EINVAL)
+    }
+
+    /// Map an existing buffer used by RTKit at a device-specified virtual address.
+    fn shmem_map(
+        _data: <Self::Data as ForeignOwnable>::Borrowed<'_>,
+        _iova: usize,
+        _size: usize,
+    ) -> Result<Self::Buffer> {
+        Err(EINVAL)
+    }
+}
+
+/// Represents `struct apple_rtkit *`.
+///
+/// # Invariants
+///
+/// The rtk pointer is valid.
+/// The data pointer is a valid pointer from T::Data::into_foreign().
+pub struct RtKit<T: Operations> {
+    rtk: *mut bindings::apple_rtkit,
+    data: *mut core::ffi::c_void,
+    _p: PhantomData<T>,
+}
+
+unsafe extern "C" fn crashed_callback<T: Operations>(cookie: *mut core::ffi::c_void) {
+    T::crashed(unsafe { T::Data::borrow(cookie) });
+}
+
+unsafe extern "C" fn recv_message_callback<T: Operations>(
+    cookie: *mut core::ffi::c_void,
+    endpoint: u8,
+    message: u64,
+) {
+    T::recv_message(unsafe { T::Data::borrow(cookie) }, endpoint, message);
+}
+
+unsafe extern "C" fn recv_message_early_callback<T: Operations>(
+    cookie: *mut core::ffi::c_void,
+    endpoint: u8,
+    message: u64,
+) -> bool {
+    T::recv_message_early(unsafe { T::Data::borrow(cookie) }, endpoint, message)
+}
+
+unsafe extern "C" fn shmem_setup_callback<T: Operations>(
+    cookie: *mut core::ffi::c_void,
+    bfr: *mut bindings::apple_rtkit_shmem,
+) -> core::ffi::c_int {
+    // SAFETY: `bfr` is a valid buffer
+    let bfr_mut = unsafe { &mut *bfr };
+
+    let buf = if bfr_mut.iova != 0 {
+        bfr_mut.is_mapped = true;
+        T::shmem_map(
+            // SAFETY: `cookie` came from a previous call to `into_foreign`.
+            unsafe { T::Data::borrow(cookie) },
+            bfr_mut.iova as usize,
+            bfr_mut.size,
+        )
+    } else {
+        bfr_mut.is_mapped = false;
+        // SAFETY: `cookie` came from a previous call to `into_foreign`.
+        T::shmem_alloc(unsafe { T::Data::borrow(cookie) }, bfr_mut.size)
+    };
+
+    let mut buf = match buf {
+        Err(e) => {
+            return e.to_kernel_errno();
+        }
+        Ok(buf) => buf,
+    };
+
+    let iova = match buf.iova() {
+        Err(e) => {
+            return e.to_kernel_errno();
+        }
+        Ok(iova) => iova,
+    };
+
+    let slice = match buf.buf() {
+        Err(e) => {
+            return e.to_kernel_errno();
+        }
+        Ok(slice) => slice,
+    };
+
+    if slice.len() < bfr_mut.size {
+        return ENOMEM.to_kernel_errno();
+    }
+
+    bfr_mut.iova = iova as u64;
+    bfr_mut.buffer = slice.as_mut_ptr() as *mut _;
+
+    // Now box the returned buffer type and stash it in the private pointer of the
+    // `apple_rtkit_shmem` struct for safekeeping.
+    match Box::try_new(buf) {
+        Err(e) => Error::from(e).to_kernel_errno(),
+        Ok(boxed) => {
+            bfr_mut.private = Box::into_raw(boxed) as *mut _;
+            0
+        }
+    }
+}
+
+unsafe extern "C" fn shmem_destroy_callback<T: Operations>(
+    _cookie: *mut core::ffi::c_void,
+    bfr: *mut bindings::apple_rtkit_shmem,
+) {
+    let bfr_mut = unsafe { &mut *bfr };
+    // SAFETY: Per shmem_setup_callback, this has to be a pointer to a Buffer if it is set.
+    if !bfr_mut.private.is_null() {
+        unsafe {
+            core::mem::drop(Box::from_raw(bfr_mut.private as *mut T::Buffer));
+        }
+        bfr_mut.private = core::ptr::null_mut();
+    }
+}
+
+impl<T: Operations> RtKit<T> {
+    const VTABLE: bindings::apple_rtkit_ops = bindings::apple_rtkit_ops {
+        crashed: Some(crashed_callback::<T>),
+        recv_message: Some(recv_message_callback::<T>),
+        recv_message_early: Some(recv_message_early_callback::<T>),
+        shmem_setup: if T::HAS_SHMEM_ALLOC || T::HAS_SHMEM_MAP {
+            Some(shmem_setup_callback::<T>)
+        } else {
+            None
+        },
+        shmem_destroy: if T::HAS_SHMEM_ALLOC || T::HAS_SHMEM_MAP {
+            Some(shmem_destroy_callback::<T>)
+        } else {
+            None
+        },
+    };
+
+    /// Creates a new RTKit client for a given device and optional mailbox name or index.
+    pub fn new(
+        dev: &dyn device::RawDevice,
+        mbox_name: Option<&'static CStr>,
+        mbox_idx: usize,
+        data: T::Data,
+    ) -> Result<Self> {
+        let ptr = data.into_foreign() as *mut _;
+        let guard = ScopeGuard::new(|| {
+            // SAFETY: `ptr` came from a previous call to `into_foreign`.
+            unsafe { T::Data::from_foreign(ptr) };
+        });
+        // SAFETY: This just calls the C init function.
+        let rtk = unsafe {
+            from_kernel_err_ptr(bindings::apple_rtkit_init(
+                dev.raw_device(),
+                ptr,
+                match mbox_name {
+                    Some(s) => s.as_char_ptr(),
+                    None => ptr::null(),
+                },
+                mbox_idx.try_into()?,
+                &Self::VTABLE,
+            ))
+        }?;
+
+        guard.dismiss();
+        // INVARIANT: `rtk` and `data` are valid here.
+        Ok(Self {
+            rtk,
+            data: ptr,
+            _p: PhantomData,
+        })
+    }
+
+    /// Boots (wakes up) the RTKit coprocessor.
+    pub fn boot(&mut self) -> Result {
+        // SAFETY: `rtk` is valid per the type invariant.
+        to_result(unsafe { bindings::apple_rtkit_boot(self.rtk) })
+    }
+
+    /// Starts a non-system endpoint.
+    pub fn start_endpoint(&mut self, endpoint: u8) -> Result {
+        // SAFETY: `rtk` is valid per the type invariant.
+        to_result(unsafe { bindings::apple_rtkit_start_ep(self.rtk, endpoint) })
+    }
+
+    /// Sends a message to a given endpoint.
+    pub fn send_message(&mut self, endpoint: u8, message: u64) -> Result {
+        // SAFETY: `rtk` is valid per the type invariant.
+        to_result(unsafe {
+            bindings::apple_rtkit_send_message(self.rtk, endpoint, message, ptr::null_mut(), false)
+        })
+    }
+}
+
+// SAFETY: `RtKit` operations require a mutable reference
+unsafe impl<T: Operations> Sync for RtKit<T> {}
+
+// SAFETY: `RtKit` operations require a mutable reference
+unsafe impl<T: Operations> Send for RtKit<T> {}
+
+impl<T: Operations> Drop for RtKit<T> {
+    fn drop(&mut self) {
+        // SAFETY: The pointer is valid by the type invariant.
+        unsafe { bindings::apple_rtkit_free(self.rtk) };
+
+        // Free context data.
+        //
+        // SAFETY: This matches the call to `into_foreign` from `new` in the success case.
+        unsafe { T::Data::from_foreign(self.data) };
+    }
+}
diff --git a/rust/kernel/soc/mod.rs b/rust/kernel/soc/mod.rs
new file mode 100644
index 000000000000..e3024042e74f
--- /dev/null
+++ b/rust/kernel/soc/mod.rs
@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! SoC drivers
+
+pub mod apple;