1 files changed, 261 insertions, 0 deletions
diff --git a/rust/kernel/amba.rs b/rust/kernel/amba.rs
new file mode 100644
index 000000000000..ec8808124a29
--- /dev/null
+++ b/rust/kernel/amba.rs
@@ -0,0 +1,261 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Amba devices and drivers.
+//!
+//! C header: [`include/linux/amba/bus.h`](../../../../include/linux/amba/bus.h)
+
+use crate::{
+    bindings, device, driver, error::from_kernel_result, io_mem::Resource, power, str::CStr,
+    to_result, types::PointerWrapper, Result, ThisModule,
+};
+
+/// A registration of an amba driver.
+pub type Registration<T> = driver::Registration<Adapter<T>>;
+
+/// Id of an Amba device.
+#[derive(Clone, Copy)]
+pub struct DeviceId {
+    /// Device id.
+    pub id: u32,
+
+    /// Mask that identifies which bits are valid in the device id.
+    pub mask: u32,
+}
+
+// SAFETY: `ZERO` is all zeroed-out and `to_rawid` stores `offset` in `amba_id::data`.
+unsafe impl const driver::RawDeviceId for DeviceId {
+    type RawType = bindings::amba_id;
+    const ZERO: Self::RawType = bindings::amba_id {
+        id: 0,
+        mask: 0,
+        data: core::ptr::null_mut(),
+    };
+
+    fn to_rawid(&self, offset: isize) -> Self::RawType {
+        bindings::amba_id {
+            id: self.id,
+            mask: self.mask,
+            data: offset as _,
+        }
+    }
+}
+
+/// An amba driver.
+pub trait Driver {
+    /// Data stored on device by driver.
+    type Data: PointerWrapper + Send + Sync + driver::DeviceRemoval = ();
+
+    /// The type that implements the power-management operations.
+    ///
+    /// The default is a type that implements no power-management operations. Drivers that do
+    /// implement them need to specify the type (commonly [`Self`]).
+    type PowerOps: power::Operations<Data = Self::Data> = power::NoOperations<Self::Data>;
+
+    /// The type holding information about each device id supported by the driver.
+    type IdInfo: 'static = ();
+
+    /// The table of device ids supported by the driver.
+    const ID_TABLE: Option<driver::IdTable<'static, DeviceId, Self::IdInfo>> = None;
+
+    /// Probes for the device with the given id.
+    fn probe(dev: &mut Device, id_info: Option<&Self::IdInfo>) -> Result<Self::Data>;
+
+    /// Cleans any resources up that are associated with the device.
+    ///
+    /// This is called when the driver is detached from the device.
+    fn remove(_data: &Self::Data) {}
+}
+
+/// An adapter for the registration of Amba drivers.
+pub struct Adapter<T: Driver>(T);
+
+impl<T: Driver> driver::DriverOps for Adapter<T> {
+    type RegType = bindings::amba_driver;
+
+    unsafe fn register(
+        reg: *mut bindings::amba_driver,
+        name: &'static CStr,
+        module: &'static ThisModule,
+    ) -> Result {
+        // SAFETY: By the safety requirements of this function (defined in the trait definition),
+        // `reg` is non-null and valid.
+        let amba = unsafe { &mut *reg };
+        amba.drv.name = name.as_char_ptr();
+        amba.drv.owner = module.0;
+        amba.probe = Some(probe_callback::<T>);
+        amba.remove = Some(remove_callback::<T>);
+        if let Some(t) = T::ID_TABLE {
+            amba.id_table = t.as_ref();
+        }
+        if cfg!(CONFIG_PM) {
+            // SAFETY: `probe_callback` sets the driver data after calling `T::Data::into_pointer`,
+            // and we guarantee that `T::Data` is the same as `T::PowerOps::Data` by a constraint
+            // in the type declaration.
+            amba.drv.pm = unsafe { power::OpsTable::<T::PowerOps>::build() };
+        }
+        // SAFETY: By the safety requirements of this function, `reg` is valid and fully
+        // initialised.
+        to_result(unsafe { bindings::amba_driver_register(reg) })
+    }
+
+    unsafe fn unregister(reg: *mut bindings::amba_driver) {
+        // SAFETY: By the safety requirements of this function (defined in the trait definition),
+        // `reg` was passed (and updated) by a previous successful call to `amba_driver_register`.
+        unsafe { bindings::amba_driver_unregister(reg) };
+    }
+}
+
+unsafe extern "C" fn probe_callback<T: Driver>(
+    adev: *mut bindings::amba_device,
+    aid: *const bindings::amba_id,
+) -> core::ffi::c_int {
+    from_kernel_result! {
+        // SAFETY: `adev` is valid by the contract with the C code. `dev` is alive only for the
+        // duration of this call, so it is guaranteed to remain alive for the lifetime of `dev`.
+        let mut dev = unsafe { Device::from_ptr(adev) };
+        // SAFETY: `aid` is valid by the requirements the contract with the C code.
+        let offset = unsafe { (*aid).data };
+        let info = if offset.is_null() {
+            None
+        } else {
+            // SAFETY: The offset comes from a previous call to `offset_from` in `IdArray::new`,
+            // which guarantees that the resulting pointer is within the table.
+            let ptr = unsafe {
+                aid.cast::<u8>()
+                    .offset(offset as _)
+                    .cast::<Option<T::IdInfo>>()
+            };
+            // SAFETY: The id table has a static lifetime, so `ptr` is guaranteed to be valid for
+            // read.
+            unsafe { (&*ptr).as_ref() }
+        };
+        let data = T::probe(&mut dev, info)?;
+        let ptr = T::Data::into_pointer(data);
+        // SAFETY: `adev` is valid for write by the contract with the C code.
+        unsafe { bindings::amba_set_drvdata(adev, ptr as _) };
+        Ok(0)
+    }
+}
+
+unsafe extern "C" fn remove_callback<T: Driver>(adev: *mut bindings::amba_device) {
+    // SAFETY: `adev` is valid by the contract with the C code.
+    let ptr = unsafe { bindings::amba_get_drvdata(adev) };
+    // SAFETY: The value returned by `amba_get_drvdata` was stored by a previous call to
+    // `amba_set_drvdata` in `probe_callback` above; the value comes from a call to
+    // `T::Data::into_pointer`.
+    let data = unsafe { T::Data::from_pointer(ptr) };
+    T::remove(&data);
+    <T::Data as driver::DeviceRemoval>::device_remove(&data);
+}
+
+/// An Amba device.
+///
+/// # Invariants
+///
+/// The field `ptr` is non-null and valid for the lifetime of the object.
+pub struct Device {
+    ptr: *mut bindings::amba_device,
+    res: Option<Resource>,
+}
+
+impl Device {
+    /// Creates a new device from the given pointer.
+    ///
+    /// # Safety
+    ///
+    /// `ptr` must be non-null and valid. It must remain valid for the lifetime of the returned
+    /// instance.
+    unsafe fn from_ptr(ptr: *mut bindings::amba_device) -> Self {
+        // SAFETY: The safety requirements of the function ensure that `ptr` is valid.
+        let dev = unsafe { &mut *ptr };
+        // INVARIANT: The safety requirements of the function ensure the lifetime invariant.
+        Self {
+            ptr,
+            res: Resource::new(dev.res.start, dev.res.end),
+        }
+    }
+
+    /// Returns the io mem resource associated with the device, if there is one.
+    ///
+    /// Ownership of the resource is transferred to the caller, so subsequent calls to this
+    /// function will return [`None`].
+    pub fn take_resource(&mut self) -> Option<Resource> {
+        self.res.take()
+    }
+
+    /// Returns the index-th irq associated with the device, if one exists.
+    pub fn irq(&self, index: usize) -> Option<u32> {
+        // SAFETY: By the type invariants, `self.ptr` is valid for read.
+        let dev = unsafe { &*self.ptr };
+        if index >= dev.irq.len() || dev.irq[index] == 0 {
+            None
+        } else {
+            Some(dev.irq[index])
+        }
+    }
+}
+
+// SAFETY: The device returned by `raw_device` is the raw Amba device.
+unsafe impl device::RawDevice for Device {
+    fn raw_device(&self) -> *mut bindings::device {
+        // SAFETY: By the type invariants, we know that `self.ptr` is non-null and valid.
+        unsafe { &mut (*self.ptr).dev }
+    }
+}
+
+/// Declares a kernel module that exposes a single amba driver.
+///
+/// # Examples
+///
+/// ```ignore
+/// # use kernel::{amba, define_amba_id_table, module_amba_driver};
+/// #
+/// struct MyDriver;
+/// impl amba::Driver for MyDriver {
+///     // [...]
+/// #   fn probe(_dev: &mut amba::Device, _id: Option<&Self::IdInfo>) -> Result {
+/// #       Ok(())
+/// #   }
+/// #   define_amba_id_table! {(), [
+/// #       ({ id: 0x00041061, mask: 0x000fffff }, None),
+/// #   ]}
+/// }
+///
+/// module_amba_driver! {
+///     type: MyDriver,
+///     name: b"module_name",
+///     author: b"Author name",
+///     license: b"GPL",
+/// }
+/// ```
+#[macro_export]
+macro_rules! module_amba_driver {
+    ($($f:tt)*) => {
+        $crate::module_driver!(<T>, $crate::amba::Adapter<T>, { $($f)* });
+    };
+}
+
+/// Defines the id table for amba devices.
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::{amba, define_amba_id_table};
+/// #
+/// # struct Sample;
+/// # impl kernel::amba::Driver for Sample {
+/// #   fn probe(_dev: &mut amba::Device, _id: Option<&Self::IdInfo>) -> Result {
+/// #       Ok(())
+/// #   }
+/// define_amba_id_table! {(), [
+///     ({ id: 0x00041061, mask: 0x000fffff }, None),
+/// ]}
+/// # }
+/// ```
+#[macro_export]
+macro_rules! define_amba_id_table {
+    ($data_type:ty, $($t:tt)*) => {
+        type IdInfo = $data_type;
+        $crate::define_id_table!(ID_TABLE, $crate::amba::DeviceId, $data_type, $($t)*);
+    };
+}