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Diffstat (limited to 'rust/kernel/platform.rs')
| -rw-r--r-- | rust/kernel/platform.rs | 519 |
1 files changed, 519 insertions, 0 deletions
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs new file mode 100644 index 000000000000..7205fe3416d3 --- /dev/null +++ b/rust/kernel/platform.rs @@ -0,0 +1,519 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Abstractions for the platform bus. +//! +//! C header: [`include/linux/platform_device.h`](srctree/include/linux/platform_device.h) + +use crate::{ + acpi, bindings, container_of, + device::{self, Bound}, + driver, + error::{from_result, to_result, Result}, + io::{mem::IoRequest, Resource}, + irq::{self, IrqRequest}, + of, + prelude::*, + types::Opaque, + ThisModule, +}; + +use core::{ + marker::PhantomData, + ptr::{addr_of_mut, NonNull}, +}; + +/// An adapter for the registration of platform drivers. +pub struct Adapter<T: Driver>(T); + +// SAFETY: A call to `unregister` for a given instance of `RegType` is guaranteed to be valid if +// a preceding call to `register` has been successful. +unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> { + type RegType = bindings::platform_driver; + + unsafe fn register( + pdrv: &Opaque<Self::RegType>, + name: &'static CStr, + module: &'static ThisModule, + ) -> Result { + let of_table = match T::OF_ID_TABLE { + Some(table) => table.as_ptr(), + None => core::ptr::null(), + }; + + let acpi_table = match T::ACPI_ID_TABLE { + Some(table) => table.as_ptr(), + None => core::ptr::null(), + }; + + // SAFETY: It's safe to set the fields of `struct platform_driver` on initialization. + unsafe { + (*pdrv.get()).driver.name = name.as_char_ptr(); + (*pdrv.get()).probe = Some(Self::probe_callback); + (*pdrv.get()).remove = Some(Self::remove_callback); + (*pdrv.get()).driver.of_match_table = of_table; + (*pdrv.get()).driver.acpi_match_table = acpi_table; + } + + // SAFETY: `pdrv` is guaranteed to be a valid `RegType`. + to_result(unsafe { bindings::__platform_driver_register(pdrv.get(), module.0) }) + } + + unsafe fn unregister(pdrv: &Opaque<Self::RegType>) { + // SAFETY: `pdrv` is guaranteed to be a valid `RegType`. + unsafe { bindings::platform_driver_unregister(pdrv.get()) }; + } +} + +impl<T: Driver + 'static> Adapter<T> { + extern "C" fn probe_callback(pdev: *mut bindings::platform_device) -> kernel::ffi::c_int { + // SAFETY: The platform bus only ever calls the probe callback with a valid pointer to a + // `struct platform_device`. + // + // INVARIANT: `pdev` is valid for the duration of `probe_callback()`. + let pdev = unsafe { &*pdev.cast::<Device<device::CoreInternal>>() }; + let info = <Self as driver::Adapter>::id_info(pdev.as_ref()); + + from_result(|| { + let data = T::probe(pdev, info)?; + + pdev.as_ref().set_drvdata(data); + Ok(0) + }) + } + + extern "C" fn remove_callback(pdev: *mut bindings::platform_device) { + // SAFETY: The platform bus only ever calls the remove callback with a valid pointer to a + // `struct platform_device`. + // + // INVARIANT: `pdev` is valid for the duration of `probe_callback()`. + let pdev = unsafe { &*pdev.cast::<Device<device::CoreInternal>>() }; + + // SAFETY: `remove_callback` is only ever called after a successful call to + // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called + // and stored a `Pin<KBox<T>>`. + let data = unsafe { pdev.as_ref().drvdata_obtain::<Pin<KBox<T>>>() }; + + T::unbind(pdev, data.as_ref()); + } +} + +impl<T: Driver + 'static> driver::Adapter for Adapter<T> { + type IdInfo = T::IdInfo; + + fn of_id_table() -> Option<of::IdTable<Self::IdInfo>> { + T::OF_ID_TABLE + } + + fn acpi_id_table() -> Option<acpi::IdTable<Self::IdInfo>> { + T::ACPI_ID_TABLE + } +} + +/// Declares a kernel module that exposes a single platform driver. +/// +/// # Examples +/// +/// ```ignore +/// kernel::module_platform_driver! { +/// type: MyDriver, +/// name: "Module name", +/// authors: ["Author name"], +/// description: "Description", +/// license: "GPL v2", +/// } +/// ``` +#[macro_export] +macro_rules! module_platform_driver { + ($($f:tt)*) => { + $crate::module_driver!(<T>, $crate::platform::Adapter<T>, { $($f)* }); + }; +} + +/// The platform driver trait. +/// +/// Drivers must implement this trait in order to get a platform driver registered. +/// +/// # Examples +/// +///``` +/// # use kernel::{acpi, bindings, c_str, device::Core, of, platform}; +/// +/// struct MyDriver; +/// +/// kernel::of_device_table!( +/// OF_TABLE, +/// MODULE_OF_TABLE, +/// <MyDriver as platform::Driver>::IdInfo, +/// [ +/// (of::DeviceId::new(c_str!("test,device")), ()) +/// ] +/// ); +/// +/// kernel::acpi_device_table!( +/// ACPI_TABLE, +/// MODULE_ACPI_TABLE, +/// <MyDriver as platform::Driver>::IdInfo, +/// [ +/// (acpi::DeviceId::new(c_str!("LNUXBEEF")), ()) +/// ] +/// ); +/// +/// impl platform::Driver for MyDriver { +/// type IdInfo = (); +/// const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE); +/// const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE); +/// +/// fn probe( +/// _pdev: &platform::Device<Core>, +/// _id_info: Option<&Self::IdInfo>, +/// ) -> Result<Pin<KBox<Self>>> { +/// Err(ENODEV) +/// } +/// } +///``` +pub trait Driver: Send { + /// The type holding driver private data about each device id supported by the driver. + // TODO: Use associated_type_defaults once stabilized: + // + // ``` + // type IdInfo: 'static = (); + // ``` + type IdInfo: 'static; + + /// The table of OF device ids supported by the driver. + const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None; + + /// The table of ACPI device ids supported by the driver. + const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = None; + + /// Platform driver probe. + /// + /// Called when a new platform device is added or discovered. + /// Implementers should attempt to initialize the device here. + fn probe(dev: &Device<device::Core>, id_info: Option<&Self::IdInfo>) + -> Result<Pin<KBox<Self>>>; + + /// Platform driver unbind. + /// + /// Called when a [`Device`] is unbound from its bound [`Driver`]. Implementing this callback + /// is optional. + /// + /// This callback serves as a place for drivers to perform teardown operations that require a + /// `&Device<Core>` or `&Device<Bound>` reference. For instance, drivers may try to perform I/O + /// operations to gracefully tear down the device. + /// + /// Otherwise, release operations for driver resources should be performed in `Self::drop`. + fn unbind(dev: &Device<device::Core>, this: Pin<&Self>) { + let _ = (dev, this); + } +} + +/// The platform device representation. +/// +/// This structure represents the Rust abstraction for a C `struct platform_device`. The +/// implementation abstracts the usage of an already existing C `struct platform_device` within Rust +/// code that we get passed from the C side. +/// +/// # Invariants +/// +/// A [`Device`] instance represents a valid `struct platform_device` created by the C portion of +/// the kernel. +#[repr(transparent)] +pub struct Device<Ctx: device::DeviceContext = device::Normal>( + Opaque<bindings::platform_device>, + PhantomData<Ctx>, +); + +impl<Ctx: device::DeviceContext> Device<Ctx> { + fn as_raw(&self) -> *mut bindings::platform_device { + self.0.get() + } + + /// Returns the resource at `index`, if any. + pub fn resource_by_index(&self, index: u32) -> Option<&Resource> { + // SAFETY: `self.as_raw()` returns a valid pointer to a `struct platform_device`. + let resource = unsafe { + bindings::platform_get_resource(self.as_raw(), bindings::IORESOURCE_MEM, index) + }; + + if resource.is_null() { + return None; + } + + // SAFETY: `resource` is a valid pointer to a `struct resource` as + // returned by `platform_get_resource`. + Some(unsafe { Resource::from_raw(resource) }) + } + + /// Returns the resource with a given `name`, if any. + pub fn resource_by_name(&self, name: &CStr) -> Option<&Resource> { + // SAFETY: `self.as_raw()` returns a valid pointer to a `struct + // platform_device` and `name` points to a valid C string. + let resource = unsafe { + bindings::platform_get_resource_byname( + self.as_raw(), + bindings::IORESOURCE_MEM, + name.as_char_ptr(), + ) + }; + + if resource.is_null() { + return None; + } + + // SAFETY: `resource` is a valid pointer to a `struct resource` as + // returned by `platform_get_resource`. + Some(unsafe { Resource::from_raw(resource) }) + } +} + +impl Device<Bound> { + /// Returns an `IoRequest` for the resource at `index`, if any. + pub fn io_request_by_index(&self, index: u32) -> Option<IoRequest<'_>> { + self.resource_by_index(index) + // SAFETY: `resource` is a valid resource for `&self` during the + // lifetime of the `IoRequest`. + .map(|resource| unsafe { IoRequest::new(self.as_ref(), resource) }) + } + + /// Returns an `IoRequest` for the resource with a given `name`, if any. + pub fn io_request_by_name(&self, name: &CStr) -> Option<IoRequest<'_>> { + self.resource_by_name(name) + // SAFETY: `resource` is a valid resource for `&self` during the + // lifetime of the `IoRequest`. + .map(|resource| unsafe { IoRequest::new(self.as_ref(), resource) }) + } +} + +macro_rules! define_irq_accessor_by_index { + ( + $(#[$meta:meta])* $fn_name:ident, + $request_fn:ident, + $reg_type:ident, + $handler_trait:ident + ) => { + $(#[$meta])* + pub fn $fn_name<'a, T: irq::$handler_trait + 'static>( + &'a self, + flags: irq::Flags, + index: u32, + name: &'static CStr, + handler: impl PinInit<T, Error> + 'a, + ) -> Result<impl PinInit<irq::$reg_type<T>, Error> + 'a> { + let request = self.$request_fn(index)?; + + Ok(irq::$reg_type::<T>::new( + request, + flags, + name, + handler, + )) + } + }; +} + +macro_rules! define_irq_accessor_by_name { + ( + $(#[$meta:meta])* $fn_name:ident, + $request_fn:ident, + $reg_type:ident, + $handler_trait:ident + ) => { + $(#[$meta])* + pub fn $fn_name<'a, T: irq::$handler_trait + 'static>( + &'a self, + flags: irq::Flags, + irq_name: &CStr, + name: &'static CStr, + handler: impl PinInit<T, Error> + 'a, + ) -> Result<impl PinInit<irq::$reg_type<T>, Error> + 'a> { + let request = self.$request_fn(irq_name)?; + + Ok(irq::$reg_type::<T>::new( + request, + flags, + name, + handler, + )) + } + }; +} + +impl Device<Bound> { + /// Returns an [`IrqRequest`] for the IRQ at the given index, if any. + pub fn irq_by_index(&self, index: u32) -> Result<IrqRequest<'_>> { + // SAFETY: `self.as_raw` returns a valid pointer to a `struct platform_device`. + let irq = unsafe { bindings::platform_get_irq(self.as_raw(), index) }; + + if irq < 0 { + return Err(Error::from_errno(irq)); + } + + // SAFETY: `irq` is guaranteed to be a valid IRQ number for `&self`. + Ok(unsafe { IrqRequest::new(self.as_ref(), irq as u32) }) + } + + /// Returns an [`IrqRequest`] for the IRQ at the given index, but does not + /// print an error if the IRQ cannot be obtained. + pub fn optional_irq_by_index(&self, index: u32) -> Result<IrqRequest<'_>> { + // SAFETY: `self.as_raw` returns a valid pointer to a `struct platform_device`. + let irq = unsafe { bindings::platform_get_irq_optional(self.as_raw(), index) }; + + if irq < 0 { + return Err(Error::from_errno(irq)); + } + + // SAFETY: `irq` is guaranteed to be a valid IRQ number for `&self`. + Ok(unsafe { IrqRequest::new(self.as_ref(), irq as u32) }) + } + + /// Returns an [`IrqRequest`] for the IRQ with the given name, if any. + pub fn irq_by_name(&self, name: &CStr) -> Result<IrqRequest<'_>> { + // SAFETY: `self.as_raw` returns a valid pointer to a `struct platform_device`. + let irq = unsafe { bindings::platform_get_irq_byname(self.as_raw(), name.as_char_ptr()) }; + + if irq < 0 { + return Err(Error::from_errno(irq)); + } + + // SAFETY: `irq` is guaranteed to be a valid IRQ number for `&self`. + Ok(unsafe { IrqRequest::new(self.as_ref(), irq as u32) }) + } + + /// Returns an [`IrqRequest`] for the IRQ with the given name, but does not + /// print an error if the IRQ cannot be obtained. + pub fn optional_irq_by_name(&self, name: &CStr) -> Result<IrqRequest<'_>> { + // SAFETY: `self.as_raw` returns a valid pointer to a `struct platform_device`. + let irq = unsafe { + bindings::platform_get_irq_byname_optional(self.as_raw(), name.as_char_ptr()) + }; + + if irq < 0 { + return Err(Error::from_errno(irq)); + } + + // SAFETY: `irq` is guaranteed to be a valid IRQ number for `&self`. + Ok(unsafe { IrqRequest::new(self.as_ref(), irq as u32) }) + } + + define_irq_accessor_by_index!( + /// Returns a [`irq::Registration`] for the IRQ at the given index. + request_irq_by_index, + irq_by_index, + Registration, + Handler + ); + define_irq_accessor_by_name!( + /// Returns a [`irq::Registration`] for the IRQ with the given name. + request_irq_by_name, + irq_by_name, + Registration, + Handler + ); + define_irq_accessor_by_index!( + /// Does the same as [`Self::request_irq_by_index`], except that it does + /// not print an error message if the IRQ cannot be obtained. + request_optional_irq_by_index, + optional_irq_by_index, + Registration, + Handler + ); + define_irq_accessor_by_name!( + /// Does the same as [`Self::request_irq_by_name`], except that it does + /// not print an error message if the IRQ cannot be obtained. + request_optional_irq_by_name, + optional_irq_by_name, + Registration, + Handler + ); + + define_irq_accessor_by_index!( + /// Returns a [`irq::ThreadedRegistration`] for the IRQ at the given index. + request_threaded_irq_by_index, + irq_by_index, + ThreadedRegistration, + ThreadedHandler + ); + define_irq_accessor_by_name!( + /// Returns a [`irq::ThreadedRegistration`] for the IRQ with the given name. + request_threaded_irq_by_name, + irq_by_name, + ThreadedRegistration, + ThreadedHandler + ); + define_irq_accessor_by_index!( + /// Does the same as [`Self::request_threaded_irq_by_index`], except + /// that it does not print an error message if the IRQ cannot be + /// obtained. + request_optional_threaded_irq_by_index, + optional_irq_by_index, + ThreadedRegistration, + ThreadedHandler + ); + define_irq_accessor_by_name!( + /// Does the same as [`Self::request_threaded_irq_by_name`], except that + /// it does not print an error message if the IRQ cannot be obtained. + request_optional_threaded_irq_by_name, + optional_irq_by_name, + ThreadedRegistration, + ThreadedHandler + ); +} + +// SAFETY: `Device` is a transparent wrapper of a type that doesn't depend on `Device`'s generic +// argument. +kernel::impl_device_context_deref!(unsafe { Device }); +kernel::impl_device_context_into_aref!(Device); + +impl crate::dma::Device for Device<device::Core> {} + +// SAFETY: Instances of `Device` are always reference-counted. +unsafe impl crate::sync::aref::AlwaysRefCounted for Device { + fn inc_ref(&self) { + // SAFETY: The existence of a shared reference guarantees that the refcount is non-zero. + unsafe { bindings::get_device(self.as_ref().as_raw()) }; + } + + unsafe fn dec_ref(obj: NonNull<Self>) { + // SAFETY: The safety requirements guarantee that the refcount is non-zero. + unsafe { bindings::platform_device_put(obj.cast().as_ptr()) } + } +} + +impl<Ctx: device::DeviceContext> AsRef<device::Device<Ctx>> for Device<Ctx> { + fn as_ref(&self) -> &device::Device<Ctx> { + // SAFETY: By the type invariant of `Self`, `self.as_raw()` is a pointer to a valid + // `struct platform_device`. + let dev = unsafe { addr_of_mut!((*self.as_raw()).dev) }; + + // SAFETY: `dev` points to a valid `struct device`. + unsafe { device::Device::from_raw(dev) } + } +} + +impl<Ctx: device::DeviceContext> TryFrom<&device::Device<Ctx>> for &Device<Ctx> { + type Error = kernel::error::Error; + + fn try_from(dev: &device::Device<Ctx>) -> Result<Self, Self::Error> { + // SAFETY: By the type invariant of `Device`, `dev.as_raw()` is a valid pointer to a + // `struct device`. + if !unsafe { bindings::dev_is_platform(dev.as_raw()) } { + return Err(EINVAL); + } + + // SAFETY: We've just verified that the bus type of `dev` equals + // `bindings::platform_bus_type`, hence `dev` must be embedded in a valid + // `struct platform_device` as guaranteed by the corresponding C code. + let pdev = unsafe { container_of!(dev.as_raw(), bindings::platform_device, dev) }; + + // SAFETY: `pdev` is a valid pointer to a `struct platform_device`. + Ok(unsafe { &*pdev.cast() }) + } +} + +// SAFETY: A `Device` is always reference-counted and can be released from any thread. +unsafe impl Send for Device {} + +// SAFETY: `Device` can be shared among threads because all methods of `Device` +// (i.e. `Device<Normal>) are thread safe. +unsafe impl Sync for Device {} |