kernel/platform.rs
1// SPDX-License-Identifier: GPL-2.0
2
3//! Abstractions for the platform bus.
4//!
5//! C header: [`include/linux/platform_device.h`](srctree/include/linux/platform_device.h)
6
7use crate::{
8 acpi, bindings, container_of,
9 device::{self, Bound},
10 driver,
11 error::{from_result, to_result, Result},
12 io::{mem::IoRequest, Resource},
13 of,
14 prelude::*,
15 types::Opaque,
16 ThisModule,
17};
18
19use core::{
20 marker::PhantomData,
21 ptr::{addr_of_mut, NonNull},
22};
23
24/// An adapter for the registration of platform drivers.
25pub struct Adapter<T: Driver>(T);
26
27// SAFETY: A call to `unregister` for a given instance of `RegType` is guaranteed to be valid if
28// a preceding call to `register` has been successful.
29unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
30 type RegType = bindings::platform_driver;
31
32 unsafe fn register(
33 pdrv: &Opaque<Self::RegType>,
34 name: &'static CStr,
35 module: &'static ThisModule,
36 ) -> Result {
37 let of_table = match T::OF_ID_TABLE {
38 Some(table) => table.as_ptr(),
39 None => core::ptr::null(),
40 };
41
42 let acpi_table = match T::ACPI_ID_TABLE {
43 Some(table) => table.as_ptr(),
44 None => core::ptr::null(),
45 };
46
47 // SAFETY: It's safe to set the fields of `struct platform_driver` on initialization.
48 unsafe {
49 (*pdrv.get()).driver.name = name.as_char_ptr();
50 (*pdrv.get()).probe = Some(Self::probe_callback);
51 (*pdrv.get()).remove = Some(Self::remove_callback);
52 (*pdrv.get()).driver.of_match_table = of_table;
53 (*pdrv.get()).driver.acpi_match_table = acpi_table;
54 }
55
56 // SAFETY: `pdrv` is guaranteed to be a valid `RegType`.
57 to_result(unsafe { bindings::__platform_driver_register(pdrv.get(), module.0) })
58 }
59
60 unsafe fn unregister(pdrv: &Opaque<Self::RegType>) {
61 // SAFETY: `pdrv` is guaranteed to be a valid `RegType`.
62 unsafe { bindings::platform_driver_unregister(pdrv.get()) };
63 }
64}
65
66impl<T: Driver + 'static> Adapter<T> {
67 extern "C" fn probe_callback(pdev: *mut bindings::platform_device) -> kernel::ffi::c_int {
68 // SAFETY: The platform bus only ever calls the probe callback with a valid pointer to a
69 // `struct platform_device`.
70 //
71 // INVARIANT: `pdev` is valid for the duration of `probe_callback()`.
72 let pdev = unsafe { &*pdev.cast::<Device<device::CoreInternal>>() };
73 let info = <Self as driver::Adapter>::id_info(pdev.as_ref());
74
75 from_result(|| {
76 let data = T::probe(pdev, info)?;
77
78 pdev.as_ref().set_drvdata(data);
79 Ok(0)
80 })
81 }
82
83 extern "C" fn remove_callback(pdev: *mut bindings::platform_device) {
84 // SAFETY: The platform bus only ever calls the remove callback with a valid pointer to a
85 // `struct platform_device`.
86 //
87 // INVARIANT: `pdev` is valid for the duration of `probe_callback()`.
88 let pdev = unsafe { &*pdev.cast::<Device<device::CoreInternal>>() };
89
90 // SAFETY: `remove_callback` is only ever called after a successful call to
91 // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
92 // and stored a `Pin<KBox<T>>`.
93 let data = unsafe { pdev.as_ref().drvdata_obtain::<Pin<KBox<T>>>() };
94
95 T::unbind(pdev, data.as_ref());
96 }
97}
98
99impl<T: Driver + 'static> driver::Adapter for Adapter<T> {
100 type IdInfo = T::IdInfo;
101
102 fn of_id_table() -> Option<of::IdTable<Self::IdInfo>> {
103 T::OF_ID_TABLE
104 }
105
106 fn acpi_id_table() -> Option<acpi::IdTable<Self::IdInfo>> {
107 T::ACPI_ID_TABLE
108 }
109}
110
111/// Declares a kernel module that exposes a single platform driver.
112///
113/// # Examples
114///
115/// ```ignore
116/// kernel::module_platform_driver! {
117/// type: MyDriver,
118/// name: "Module name",
119/// authors: ["Author name"],
120/// description: "Description",
121/// license: "GPL v2",
122/// }
123/// ```
124#[macro_export]
125macro_rules! module_platform_driver {
126 ($($f:tt)*) => {
127 $crate::module_driver!(<T>, $crate::platform::Adapter<T>, { $($f)* });
128 };
129}
130
131/// The platform driver trait.
132///
133/// Drivers must implement this trait in order to get a platform driver registered.
134///
135/// # Examples
136///
137///```
138/// # use kernel::{acpi, bindings, c_str, device::Core, of, platform};
139///
140/// struct MyDriver;
141///
142/// kernel::of_device_table!(
143/// OF_TABLE,
144/// MODULE_OF_TABLE,
145/// <MyDriver as platform::Driver>::IdInfo,
146/// [
147/// (of::DeviceId::new(c_str!("test,device")), ())
148/// ]
149/// );
150///
151/// kernel::acpi_device_table!(
152/// ACPI_TABLE,
153/// MODULE_ACPI_TABLE,
154/// <MyDriver as platform::Driver>::IdInfo,
155/// [
156/// (acpi::DeviceId::new(c_str!("LNUXBEEF")), ())
157/// ]
158/// );
159///
160/// impl platform::Driver for MyDriver {
161/// type IdInfo = ();
162/// const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
163/// const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
164///
165/// fn probe(
166/// _pdev: &platform::Device<Core>,
167/// _id_info: Option<&Self::IdInfo>,
168/// ) -> Result<Pin<KBox<Self>>> {
169/// Err(ENODEV)
170/// }
171/// }
172///```
173pub trait Driver: Send {
174 /// The type holding driver private data about each device id supported by the driver.
175 // TODO: Use associated_type_defaults once stabilized:
176 //
177 // ```
178 // type IdInfo: 'static = ();
179 // ```
180 type IdInfo: 'static;
181
182 /// The table of OF device ids supported by the driver.
183 const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
184
185 /// The table of ACPI device ids supported by the driver.
186 const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = None;
187
188 /// Platform driver probe.
189 ///
190 /// Called when a new platform device is added or discovered.
191 /// Implementers should attempt to initialize the device here.
192 fn probe(dev: &Device<device::Core>, id_info: Option<&Self::IdInfo>)
193 -> Result<Pin<KBox<Self>>>;
194
195 /// Platform driver unbind.
196 ///
197 /// Called when a [`Device`] is unbound from its bound [`Driver`]. Implementing this callback
198 /// is optional.
199 ///
200 /// This callback serves as a place for drivers to perform teardown operations that require a
201 /// `&Device<Core>` or `&Device<Bound>` reference. For instance, drivers may try to perform I/O
202 /// operations to gracefully tear down the device.
203 ///
204 /// Otherwise, release operations for driver resources should be performed in `Self::drop`.
205 fn unbind(dev: &Device<device::Core>, this: Pin<&Self>) {
206 let _ = (dev, this);
207 }
208}
209
210/// The platform device representation.
211///
212/// This structure represents the Rust abstraction for a C `struct platform_device`. The
213/// implementation abstracts the usage of an already existing C `struct platform_device` within Rust
214/// code that we get passed from the C side.
215///
216/// # Invariants
217///
218/// A [`Device`] instance represents a valid `struct platform_device` created by the C portion of
219/// the kernel.
220#[repr(transparent)]
221pub struct Device<Ctx: device::DeviceContext = device::Normal>(
222 Opaque<bindings::platform_device>,
223 PhantomData<Ctx>,
224);
225
226impl<Ctx: device::DeviceContext> Device<Ctx> {
227 fn as_raw(&self) -> *mut bindings::platform_device {
228 self.0.get()
229 }
230
231 /// Returns the resource at `index`, if any.
232 pub fn resource_by_index(&self, index: u32) -> Option<&Resource> {
233 // SAFETY: `self.as_raw()` returns a valid pointer to a `struct platform_device`.
234 let resource = unsafe {
235 bindings::platform_get_resource(self.as_raw(), bindings::IORESOURCE_MEM, index)
236 };
237
238 if resource.is_null() {
239 return None;
240 }
241
242 // SAFETY: `resource` is a valid pointer to a `struct resource` as
243 // returned by `platform_get_resource`.
244 Some(unsafe { Resource::from_raw(resource) })
245 }
246
247 /// Returns the resource with a given `name`, if any.
248 pub fn resource_by_name(&self, name: &CStr) -> Option<&Resource> {
249 // SAFETY: `self.as_raw()` returns a valid pointer to a `struct
250 // platform_device` and `name` points to a valid C string.
251 let resource = unsafe {
252 bindings::platform_get_resource_byname(
253 self.as_raw(),
254 bindings::IORESOURCE_MEM,
255 name.as_char_ptr(),
256 )
257 };
258
259 if resource.is_null() {
260 return None;
261 }
262
263 // SAFETY: `resource` is a valid pointer to a `struct resource` as
264 // returned by `platform_get_resource`.
265 Some(unsafe { Resource::from_raw(resource) })
266 }
267}
268
269impl Device<Bound> {
270 /// Returns an `IoRequest` for the resource at `index`, if any.
271 pub fn io_request_by_index(&self, index: u32) -> Option<IoRequest<'_>> {
272 self.resource_by_index(index)
273 // SAFETY: `resource` is a valid resource for `&self` during the
274 // lifetime of the `IoRequest`.
275 .map(|resource| unsafe { IoRequest::new(self.as_ref(), resource) })
276 }
277
278 /// Returns an `IoRequest` for the resource with a given `name`, if any.
279 pub fn io_request_by_name(&self, name: &CStr) -> Option<IoRequest<'_>> {
280 self.resource_by_name(name)
281 // SAFETY: `resource` is a valid resource for `&self` during the
282 // lifetime of the `IoRequest`.
283 .map(|resource| unsafe { IoRequest::new(self.as_ref(), resource) })
284 }
285}
286
287// SAFETY: `Device` is a transparent wrapper of a type that doesn't depend on `Device`'s generic
288// argument.
289kernel::impl_device_context_deref!(unsafe { Device });
290kernel::impl_device_context_into_aref!(Device);
291
292impl crate::dma::Device for Device<device::Core> {}
293
294// SAFETY: Instances of `Device` are always reference-counted.
295unsafe impl crate::types::AlwaysRefCounted for Device {
296 fn inc_ref(&self) {
297 // SAFETY: The existence of a shared reference guarantees that the refcount is non-zero.
298 unsafe { bindings::get_device(self.as_ref().as_raw()) };
299 }
300
301 unsafe fn dec_ref(obj: NonNull<Self>) {
302 // SAFETY: The safety requirements guarantee that the refcount is non-zero.
303 unsafe { bindings::platform_device_put(obj.cast().as_ptr()) }
304 }
305}
306
307impl<Ctx: device::DeviceContext> AsRef<device::Device<Ctx>> for Device<Ctx> {
308 fn as_ref(&self) -> &device::Device<Ctx> {
309 // SAFETY: By the type invariant of `Self`, `self.as_raw()` is a pointer to a valid
310 // `struct platform_device`.
311 let dev = unsafe { addr_of_mut!((*self.as_raw()).dev) };
312
313 // SAFETY: `dev` points to a valid `struct device`.
314 unsafe { device::Device::from_raw(dev) }
315 }
316}
317
318impl<Ctx: device::DeviceContext> TryFrom<&device::Device<Ctx>> for &Device<Ctx> {
319 type Error = kernel::error::Error;
320
321 fn try_from(dev: &device::Device<Ctx>) -> Result<Self, Self::Error> {
322 // SAFETY: By the type invariant of `Device`, `dev.as_raw()` is a valid pointer to a
323 // `struct device`.
324 if !unsafe { bindings::dev_is_platform(dev.as_raw()) } {
325 return Err(EINVAL);
326 }
327
328 // SAFETY: We've just verified that the bus type of `dev` equals
329 // `bindings::platform_bus_type`, hence `dev` must be embedded in a valid
330 // `struct platform_device` as guaranteed by the corresponding C code.
331 let pdev = unsafe { container_of!(dev.as_raw(), bindings::platform_device, dev) };
332
333 // SAFETY: `pdev` is a valid pointer to a `struct platform_device`.
334 Ok(unsafe { &*pdev.cast() })
335 }
336}
337
338// SAFETY: A `Device` is always reference-counted and can be released from any thread.
339unsafe impl Send for Device {}
340
341// SAFETY: `Device` can be shared among threads because all methods of `Device`
342// (i.e. `Device<Normal>) are thread safe.
343unsafe impl Sync for Device {}