kernel/drm/
device.rs

1// SPDX-License-Identifier: GPL-2.0 OR MIT
2
3//! DRM device.
4//!
5//! C header: [`include/linux/drm/drm_device.h`](srctree/include/linux/drm/drm_device.h)
6
7use crate::{
8    alloc::allocator::Kmalloc,
9    bindings, device, drm,
10    drm::driver::AllocImpl,
11    error::from_err_ptr,
12    error::Result,
13    prelude::*,
14    types::{ARef, AlwaysRefCounted, Opaque},
15};
16use core::{alloc::Layout, mem, ops::Deref, ptr, ptr::NonNull};
17
18#[cfg(CONFIG_DRM_LEGACY)]
19macro_rules! drm_legacy_fields {
20    ( $($field:ident: $val:expr),* $(,)? ) => {
21        bindings::drm_driver {
22            $( $field: $val ),*,
23            firstopen: None,
24            preclose: None,
25            dma_ioctl: None,
26            dma_quiescent: None,
27            context_dtor: None,
28            irq_handler: None,
29            irq_preinstall: None,
30            irq_postinstall: None,
31            irq_uninstall: None,
32            get_vblank_counter: None,
33            enable_vblank: None,
34            disable_vblank: None,
35            dev_priv_size: 0,
36        }
37    }
38}
39
40#[cfg(not(CONFIG_DRM_LEGACY))]
41macro_rules! drm_legacy_fields {
42    ( $($field:ident: $val:expr),* $(,)? ) => {
43        bindings::drm_driver {
44            $( $field: $val ),*
45        }
46    }
47}
48
49/// A typed DRM device with a specific `drm::Driver` implementation.
50///
51/// The device is always reference-counted.
52///
53/// # Invariants
54///
55/// `self.dev` is a valid instance of a `struct device`.
56#[repr(C)]
57pub struct Device<T: drm::Driver> {
58    dev: Opaque<bindings::drm_device>,
59    data: T::Data,
60}
61
62impl<T: drm::Driver> Device<T> {
63    const VTABLE: bindings::drm_driver = drm_legacy_fields! {
64        load: None,
65        open: Some(drm::File::<T::File>::open_callback),
66        postclose: Some(drm::File::<T::File>::postclose_callback),
67        unload: None,
68        release: Some(Self::release),
69        master_set: None,
70        master_drop: None,
71        debugfs_init: None,
72        gem_create_object: T::Object::ALLOC_OPS.gem_create_object,
73        prime_handle_to_fd: T::Object::ALLOC_OPS.prime_handle_to_fd,
74        prime_fd_to_handle: T::Object::ALLOC_OPS.prime_fd_to_handle,
75        gem_prime_import: T::Object::ALLOC_OPS.gem_prime_import,
76        gem_prime_import_sg_table: T::Object::ALLOC_OPS.gem_prime_import_sg_table,
77        dumb_create: T::Object::ALLOC_OPS.dumb_create,
78        dumb_map_offset: T::Object::ALLOC_OPS.dumb_map_offset,
79        show_fdinfo: None,
80        fbdev_probe: None,
81
82        major: T::INFO.major,
83        minor: T::INFO.minor,
84        patchlevel: T::INFO.patchlevel,
85        name: T::INFO.name.as_char_ptr().cast_mut(),
86        desc: T::INFO.desc.as_char_ptr().cast_mut(),
87
88        driver_features: drm::driver::FEAT_GEM,
89        ioctls: T::IOCTLS.as_ptr(),
90        num_ioctls: T::IOCTLS.len() as i32,
91        fops: &Self::GEM_FOPS,
92    };
93
94    const GEM_FOPS: bindings::file_operations = drm::gem::create_fops();
95
96    /// Create a new `drm::Device` for a `drm::Driver`.
97    pub fn new(dev: &device::Device, data: impl PinInit<T::Data, Error>) -> Result<ARef<Self>> {
98        // `__drm_dev_alloc` uses `kmalloc()` to allocate memory, hence ensure a `kmalloc()`
99        // compatible `Layout`.
100        let layout = Kmalloc::aligned_layout(Layout::new::<Self>());
101
102        // SAFETY:
103        // - `VTABLE`, as a `const` is pinned to the read-only section of the compilation,
104        // - `dev` is valid by its type invarants,
105        let raw_drm: *mut Self = unsafe {
106            bindings::__drm_dev_alloc(
107                dev.as_raw(),
108                &Self::VTABLE,
109                layout.size(),
110                mem::offset_of!(Self, dev),
111            )
112        }
113        .cast();
114        let raw_drm = NonNull::new(from_err_ptr(raw_drm)?).ok_or(ENOMEM)?;
115
116        // SAFETY: `raw_drm` is a valid pointer to `Self`.
117        let raw_data = unsafe { ptr::addr_of_mut!((*raw_drm.as_ptr()).data) };
118
119        // SAFETY:
120        // - `raw_data` is a valid pointer to uninitialized memory.
121        // - `raw_data` will not move until it is dropped.
122        unsafe { data.__pinned_init(raw_data) }.inspect_err(|_| {
123            // SAFETY: `raw_drm` is a valid pointer to `Self`, given that `__drm_dev_alloc` was
124            // successful.
125            let drm_dev = unsafe { Self::into_drm_device(raw_drm) };
126
127            // SAFETY: `__drm_dev_alloc()` was successful, hence `drm_dev` must be valid and the
128            // refcount must be non-zero.
129            unsafe { bindings::drm_dev_put(drm_dev) };
130        })?;
131
132        // SAFETY: The reference count is one, and now we take ownership of that reference as a
133        // `drm::Device`.
134        Ok(unsafe { ARef::from_raw(raw_drm) })
135    }
136
137    pub(crate) fn as_raw(&self) -> *mut bindings::drm_device {
138        self.dev.get()
139    }
140
141    /// # Safety
142    ///
143    /// `ptr` must be a valid pointer to a `struct device` embedded in `Self`.
144    unsafe fn from_drm_device(ptr: *const bindings::drm_device) -> *mut Self {
145        // SAFETY: By the safety requirements of this function `ptr` is a valid pointer to a
146        // `struct drm_device` embedded in `Self`.
147        unsafe { crate::container_of!(Opaque::cast_from(ptr), Self, dev) }.cast_mut()
148    }
149
150    /// # Safety
151    ///
152    /// `ptr` must be a valid pointer to `Self`.
153    unsafe fn into_drm_device(ptr: NonNull<Self>) -> *mut bindings::drm_device {
154        // SAFETY: By the safety requirements of this function, `ptr` is a valid pointer to `Self`.
155        unsafe { &raw mut (*ptr.as_ptr()).dev }.cast()
156    }
157
158    /// Not intended to be called externally, except via declare_drm_ioctls!()
159    ///
160    /// # Safety
161    ///
162    /// Callers must ensure that `ptr` is valid, non-null, and has a non-zero reference count,
163    /// i.e. it must be ensured that the reference count of the C `struct drm_device` `ptr` points
164    /// to can't drop to zero, for the duration of this function call and the entire duration when
165    /// the returned reference exists.
166    ///
167    /// Additionally, callers must ensure that the `struct device`, `ptr` is pointing to, is
168    /// embedded in `Self`.
169    #[doc(hidden)]
170    pub unsafe fn from_raw<'a>(ptr: *const bindings::drm_device) -> &'a Self {
171        // SAFETY: By the safety requirements of this function `ptr` is a valid pointer to a
172        // `struct drm_device` embedded in `Self`.
173        let ptr = unsafe { Self::from_drm_device(ptr) };
174
175        // SAFETY: `ptr` is valid by the safety requirements of this function.
176        unsafe { &*ptr.cast() }
177    }
178
179    extern "C" fn release(ptr: *mut bindings::drm_device) {
180        // SAFETY: `ptr` is a valid pointer to a `struct drm_device` and embedded in `Self`.
181        let this = unsafe { Self::from_drm_device(ptr) };
182
183        // SAFETY:
184        // - When `release` runs it is guaranteed that there is no further access to `this`.
185        // - `this` is valid for dropping.
186        unsafe { core::ptr::drop_in_place(this) };
187    }
188}
189
190impl<T: drm::Driver> Deref for Device<T> {
191    type Target = T::Data;
192
193    fn deref(&self) -> &Self::Target {
194        &self.data
195    }
196}
197
198// SAFETY: DRM device objects are always reference counted and the get/put functions
199// satisfy the requirements.
200unsafe impl<T: drm::Driver> AlwaysRefCounted for Device<T> {
201    fn inc_ref(&self) {
202        // SAFETY: The existence of a shared reference guarantees that the refcount is non-zero.
203        unsafe { bindings::drm_dev_get(self.as_raw()) };
204    }
205
206    unsafe fn dec_ref(obj: NonNull<Self>) {
207        // SAFETY: `obj` is a valid pointer to `Self`.
208        let drm_dev = unsafe { Self::into_drm_device(obj) };
209
210        // SAFETY: The safety requirements guarantee that the refcount is non-zero.
211        unsafe { bindings::drm_dev_put(drm_dev) };
212    }
213}
214
215impl<T: drm::Driver> AsRef<device::Device> for Device<T> {
216    fn as_ref(&self) -> &device::Device {
217        // SAFETY: `bindings::drm_device::dev` is valid as long as the DRM device itself is valid,
218        // which is guaranteed by the type invariant.
219        unsafe { device::Device::from_raw((*self.as_raw()).dev) }
220    }
221}
222
223// SAFETY: A `drm::Device` can be released from any thread.
224unsafe impl<T: drm::Driver> Send for Device<T> {}
225
226// SAFETY: A `drm::Device` can be shared among threads because all immutable methods are protected
227// by the synchronization in `struct drm_device`.
228unsafe impl<T: drm::Driver> Sync for Device<T> {}
kernel/drm/device.rs

kernel/drm/
device.rs
