This commit adds some traits for registering DRM devices with KMS support,
implemented through the kernel::drm::kms::KmsDriver trait. Devices which
don't have KMS support can simply use PhantomData<Self>.
Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
---
V3:
* Get rid of Kms, long live KmsDriver
After Daniel pointed out that we should just make KmsDriver a supertrait
of Driver, it immediately occurred to me that there's no actual need for
Kms to be a separate trait at all. So, drop Kms entirely and move its
requirements over to KmsDriver.
* Drop fbdev module entirely and move fbdev related setup into AllocImpl
(Daniel)
* Rebase to use drm_client_setup()
TODO:
* Generate feature flags automatically, these shouldn't need to be
specified by the user
Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
---
rust/bindings/bindings_helper.h | 6 ++
rust/kernel/drm/device.rs | 10 +-
rust/kernel/drm/drv.rs | 56 ++++++++--
rust/kernel/drm/gem/mod.rs | 4 +
rust/kernel/drm/gem/shmem.rs | 4 +
rust/kernel/drm/kms.rs | 186 ++++++++++++++++++++++++++++++++
rust/kernel/drm/mod.rs | 1 +
7 files changed, 258 insertions(+), 9 deletions(-)
create mode 100644 rust/kernel/drm/kms.rs
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index ca857fb00b1a5..e1ed4f40c8e89 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -6,10 +6,16 @@
* Sorted alphabetically.
*/
+#include <drm/drm_atomic.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/clients/drm_client_setup.h>
#include <drm/drm_device.h>
#include <drm/drm_drv.h>
#include <drm/drm_file.h>
+#include <drm/drm_fbdev_dma.h>
+#include <drm/drm_fbdev_shmem.h>
#include <drm/drm_gem.h>
+#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_gem_shmem_helper.h>
#include <drm/drm_ioctl.h>
#include <kunit/test.h>
diff --git a/rust/kernel/drm/device.rs b/rust/kernel/drm/device.rs
index 5b4db2dfe87f5..cf063de387329 100644
--- a/rust/kernel/drm/device.rs
+++ b/rust/kernel/drm/device.rs
@@ -5,8 +5,8 @@
//! C header: [`include/linux/drm/drm_device.h`](srctree/include/linux/drm/drm_device.h)
use crate::{
- bindings, device, drm,
- drm::drv::AllocImpl,
+ bindings, device,
+ drm::{self, drv::AllocImpl, kms::private::KmsImpl as KmsImplPrivate},
error::code::*,
error::from_err_ptr,
error::Result,
@@ -73,7 +73,7 @@ impl<T: drm::drv::Driver> Device<T> {
dumb_create: T::Object::ALLOC_OPS.dumb_create,
dumb_map_offset: T::Object::ALLOC_OPS.dumb_map_offset,
show_fdinfo: None,
- fbdev_probe: None,
+ fbdev_probe: T::Object::ALLOC_OPS.fbdev_probe,
major: T::INFO.major,
minor: T::INFO.minor,
@@ -153,6 +153,10 @@ pub fn data(&self) -> <T::Data as ForeignOwnable>::Borrowed<'_> {
// SAFETY: `Self::data` is always converted and set on device creation.
unsafe { <T::Data as ForeignOwnable>::from_foreign(drm.raw_data()) };
}
+
+ pub(crate) const fn has_kms() -> bool {
+ <T::Kms as KmsImplPrivate>::MODE_CONFIG_OPS.is_some()
+ }
}
// SAFETY: DRM device objects are always reference counted and the get/put functions
diff --git a/rust/kernel/drm/drv.rs b/rust/kernel/drm/drv.rs
index e42e266bdd0da..3e09e130730f6 100644
--- a/rust/kernel/drm/drv.rs
+++ b/rust/kernel/drm/drv.rs
@@ -6,14 +6,15 @@
use crate::{
alloc::flags::*,
- bindings,
+ bindings, device,
devres::Devres,
- drm,
+ drm::{self, kms::private::KmsImpl as KmsImplPrivate},
error::{Error, Result},
private::Sealed,
str::CStr,
types::{ARef, ForeignOwnable},
};
+use core::ptr::null;
use macros::vtable;
/// Driver use the GEM memory manager. This should be set for all modern drivers.
@@ -115,6 +116,12 @@ pub struct AllocOps {
offset: *mut u64,
) -> core::ffi::c_int,
>,
+ pub(crate) fbdev_probe: Option<
+ unsafe extern "C" fn(
+ fbdev_helper: *mut bindings::drm_fb_helper,
+ sizes: *mut bindings::drm_fb_helper_surface_size,
+ ) -> core::ffi::c_int,
+ >,
}
/// Trait for memory manager implementations. Implemented internally.
@@ -142,6 +149,14 @@ pub trait Driver {
/// The type used to represent a DRM File (client)
type File: drm::file::DriverFile;
+ /// The KMS implementation for this driver.
+ ///
+ /// Drivers that wish to support KMS should pass their implementation of `drm::kms::KmsDriver`
+ /// here. Drivers which do not have KMS support can simply pass `drm::kms::NoKms` here.
+ type Kms: drm::kms::KmsImpl<Driver = Self>
+ where
+ Self: Sized;
+
/// Driver metadata
const INFO: DriverInfo;
@@ -159,21 +174,44 @@ pub trait Driver {
impl<T: Driver> Registration<T> {
/// Creates a new [`Registration`] and registers it.
- pub fn new(drm: ARef<drm::device::Device<T>>, flags: usize) -> Result<Self> {
+ pub fn new(dev: &device::Device, data: T::Data, flags: usize) -> Result<Self> {
+ let drm = drm::device::Device::<T>::new(dev, data)?;
+ let has_kms = drm::device::Device::<T>::has_kms();
+
+ let mode_config_info = if has_kms {
+ // SAFETY: We have yet to register this device
+ Some(unsafe { T::Kms::setup_kms(&drm)? })
+ } else {
+ None
+ };
+
// SAFETY: Safe by the invariants of `drm::device::Device`.
let ret = unsafe { bindings::drm_dev_register(drm.as_raw(), flags) };
if ret < 0 {
return Err(Error::from_errno(ret));
}
+ #[cfg(CONFIG_DRM_CLIENT = "y")]
+ if has_kms {
+ if let Some(ref info) = mode_config_info {
+ if let Some(fourcc) = info.preferred_fourcc {
+ // SAFETY: We just registered `drm` above, fulfilling the C API requirements
+ unsafe { bindings::drm_client_setup_with_fourcc(drm.as_raw(), fourcc) }
+ } else {
+ // SAFETY: We just registered `drm` above, fulfilling the C API requirements
+ unsafe { bindings::drm_client_setup(drm.as_raw(), null()) }
+ }
+ }
+ }
+
Ok(Self(drm))
}
/// Same as [`Registration::new`}, but transfers ownership of the [`Registration`] to `Devres`.
- pub fn new_foreign_owned(drm: ARef<drm::device::Device<T>>, flags: usize) -> Result {
- let reg = Registration::<T>::new(drm.clone(), flags)?;
+ pub fn new_foreign_owned(dev: &device::Device, data: T::Data, flags: usize) -> Result {
+ let reg = Registration::<T>::new(dev, data, flags)?;
- Devres::new_foreign_owned(drm.as_ref(), reg, GFP_KERNEL)
+ Devres::new_foreign_owned(dev, reg, GFP_KERNEL)
}
/// Returns a reference to the `Device` instance for this registration.
@@ -195,5 +233,11 @@ fn drop(&mut self) {
// SAFETY: Safe by the invariant of `ARef<drm::device::Device<T>>`. The existance of this
// `Registration` also guarantees the this `drm::device::Device` is actually registered.
unsafe { bindings::drm_dev_unregister(self.0.as_raw()) };
+
+ if drm::device::Device::<T>::has_kms() {
+ // SAFETY: We just checked above that KMS was setup for this device, so this is safe to
+ // call
+ unsafe { bindings::drm_atomic_helper_shutdown(self.0.as_raw()) }
+ }
}
}
diff --git a/rust/kernel/drm/gem/mod.rs b/rust/kernel/drm/gem/mod.rs
index 3fcab497cc2a5..605b0a22ac08b 100644
--- a/rust/kernel/drm/gem/mod.rs
+++ b/rust/kernel/drm/gem/mod.rs
@@ -300,6 +300,10 @@ impl<T: DriverObject> drv::AllocImpl for Object<T> {
gem_prime_import_sg_table: None,
dumb_create: None,
dumb_map_offset: None,
+ #[cfg(CONFIG_DRM_FBDEV_EMULATION = "y")]
+ fbdev_probe: Some(bindings::drm_fbdev_dma_driver_fbdev_probe),
+ #[cfg(CONFIG_DRM_FBDEV_EMULATION = "n")]
+ fbdev_probe: None,
};
}
diff --git a/rust/kernel/drm/gem/shmem.rs b/rust/kernel/drm/gem/shmem.rs
index 92da0d7d59912..9c0162b268aa8 100644
--- a/rust/kernel/drm/gem/shmem.rs
+++ b/rust/kernel/drm/gem/shmem.rs
@@ -279,6 +279,10 @@ impl<T: DriverObject> drv::AllocImpl for Object<T> {
gem_prime_import_sg_table: Some(bindings::drm_gem_shmem_prime_import_sg_table),
dumb_create: Some(bindings::drm_gem_shmem_dumb_create),
dumb_map_offset: None,
+ #[cfg(CONFIG_DRM_FBDEV_EMULATION = "y")]
+ fbdev_probe: Some(bindings::drm_fbdev_shmem_driver_fbdev_probe),
+ #[cfg(CONFIG_DRM_FBDEV_EMULATION = "n")]
+ fbdev_probe: None,
};
}
diff --git a/rust/kernel/drm/kms.rs b/rust/kernel/drm/kms.rs
new file mode 100644
index 0000000000000..78970c69f4cda
--- /dev/null
+++ b/rust/kernel/drm/kms.rs
@@ -0,0 +1,186 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+
+//! KMS driver abstractions for rust.
+
+use crate::{
+ device,
+ drm::{device::Device, drv::Driver},
+ error::to_result,
+ prelude::*,
+ types::*,
+};
+use bindings;
+use core::{marker::PhantomData, ops::Deref};
+
+/// The C vtable for a [`Device`].
+///
+/// This is created internally by DRM.
+pub struct ModeConfigOps {
+ pub(crate) kms_vtable: bindings::drm_mode_config_funcs,
+ pub(crate) kms_helper_vtable: bindings::drm_mode_config_helper_funcs,
+}
+
+/// A trait representing a type that can be used for setting up KMS, or a stub.
+///
+/// For drivers which don't have KMS support, the methods provided by this trait may be stubs. It is
+/// implemented internally by DRM.
+pub trait KmsImpl: private::KmsImpl {}
+
+pub(crate) mod private {
+ use super::*;
+
+ /// Private callback implemented internally by DRM for setting up KMS on a device, or stubbing
+ /// the KMS setup for devices which don't have KMS support.
+ #[allow(unreachable_pub)]
+ pub trait KmsImpl {
+ /// The parent driver for this KMS implementation
+ type Driver: Driver;
+
+ /// The optional KMS callback operations for this driver.
+ const MODE_CONFIG_OPS: Option<ModeConfigOps>;
+
+ /// The callback for setting up KMS on a device
+ ///
+ /// # Safety
+ ///
+ /// `drm` must be unregistered.
+ unsafe fn setup_kms(_drm: &Device<Self::Driver>) -> Result<ModeConfigInfo> {
+ build_error::build_error("This should never be reachable")
+ }
+ }
+}
+
+/// A [`Device`] with KMS initialized that has not been registered with userspace.
+///
+/// This type is identical to [`Device`], except that it is able to create new static KMS resources.
+/// It represents a KMS device that is not yet visible to userspace, and also contains miscellaneous
+/// state required during the initialization process of a [`Device`].
+pub struct UnregisteredKmsDevice<'a, T: Driver> {
+ drm: &'a Device<T>,
+}
+
+impl<'a, T: Driver> Deref for UnregisteredKmsDevice<'a, T> {
+ type Target = Device<T>;
+
+ fn deref(&self) -> &Self::Target {
+ self.drm
+ }
+}
+
+impl<'a, T: Driver> UnregisteredKmsDevice<'a, T> {
+ /// Construct a new [`UnregisteredKmsDevice`].
+ ///
+ /// # Safety
+ ///
+ /// The caller promises that `drm` is an unregistered [`Device`].
+ pub(crate) unsafe fn new(drm: &'a Device<T>) -> Self {
+ Self { drm }
+ }
+}
+
+/// A trait which must be implemented by drivers that wish to support KMS
+///
+/// It should be implemented for the same type that implements [`Driver`]. Drivers which don't
+/// support KMS should use [`PhantomData<Self>`].
+///
+/// [`PhantomData<Self>`]: PhantomData
+#[vtable]
+pub trait KmsDriver: Driver {
+ /// Return a [`ModeConfigInfo`] structure for this [`device::Device`].
+ fn mode_config_info(
+ dev: &device::Device,
+ drm_data: <Self::Data as ForeignOwnable>::Borrowed<'_>,
+ ) -> Result<ModeConfigInfo>;
+
+ /// Create mode objects like [`crtc::Crtc`], [`plane::Plane`], etc. for this device
+ fn create_objects(drm: &UnregisteredKmsDevice<'_, Self>) -> Result
+ where
+ Self: Sized;
+}
+
+impl<T: KmsDriver> private::KmsImpl for T {
+ type Driver = Self;
+
+ const MODE_CONFIG_OPS: Option<ModeConfigOps> = Some(ModeConfigOps {
+ kms_vtable: bindings::drm_mode_config_funcs {
+ atomic_check: Some(bindings::drm_atomic_helper_check),
+ fb_create: Some(bindings::drm_gem_fb_create),
+ mode_valid: None,
+ atomic_commit: Some(bindings::drm_atomic_helper_commit),
+ get_format_info: None,
+ atomic_state_free: None,
+ atomic_state_alloc: None,
+ atomic_state_clear: None,
+ },
+
+ kms_helper_vtable: bindings::drm_mode_config_helper_funcs {
+ atomic_commit_setup: None,
+ atomic_commit_tail: None,
+ },
+ });
+
+ unsafe fn setup_kms(drm: &Device<Self::Driver>) -> Result<ModeConfigInfo> {
+ let mode_config_info = T::mode_config_info(drm.as_ref(), drm.data())?;
+
+ // SAFETY: `MODE_CONFIG_OPS` is always Some() in this implementation
+ let ops = unsafe { T::MODE_CONFIG_OPS.as_ref().unwrap_unchecked() };
+
+ // SAFETY:
+ // - This function can only be called before registration via our safety contract.
+ // - Before registration, we are the only ones with access to this device.
+ unsafe {
+ (*drm.as_raw()).mode_config = bindings::drm_mode_config {
+ funcs: &ops.kms_vtable,
+ helper_private: &ops.kms_helper_vtable,
+ min_width: mode_config_info.min_resolution.0,
+ min_height: mode_config_info.min_resolution.1,
+ max_width: mode_config_info.max_resolution.0,
+ max_height: mode_config_info.max_resolution.1,
+ cursor_width: mode_config_info.max_cursor.0,
+ cursor_height: mode_config_info.max_cursor.1,
+ preferred_depth: mode_config_info.preferred_depth,
+ ..Default::default()
+ };
+ }
+
+ // SAFETY: We just setup all of the required info this function needs in `drm_device`
+ to_result(unsafe { bindings::drmm_mode_config_init(drm.as_raw()) })?;
+
+ // SAFETY: `drm` is guaranteed to be unregistered via our safety contract.
+ let drm = unsafe { UnregisteredKmsDevice::new(drm) };
+
+ T::create_objects(&drm)?;
+
+ // TODO: Eventually add a hook to customize how state readback happens, for now just reset
+ // SAFETY: Since all static modesetting objects were created in `T::create_objects()`, and
+ // that is the only place they can be created, this fulfills the C API requirements.
+ unsafe { bindings::drm_mode_config_reset(drm.as_raw()) };
+
+ Ok(mode_config_info)
+ }
+}
+
+impl<T: KmsDriver> KmsImpl for T {}
+
+impl<T: Driver> private::KmsImpl for PhantomData<T> {
+ type Driver = T;
+
+ const MODE_CONFIG_OPS: Option<ModeConfigOps> = None;
+}
+
+impl<T: Driver> KmsImpl for PhantomData<T> {}
+
+/// Various device-wide information for a [`Device`] that is provided during initialization.
+#[derive(Copy, Clone)]
+pub struct ModeConfigInfo {
+ /// The minimum (w, h) resolution this driver can support
+ pub min_resolution: (i32, i32),
+ /// The maximum (w, h) resolution this driver can support
+ pub max_resolution: (i32, i32),
+ /// The maximum (w, h) cursor size this driver can support
+ pub max_cursor: (u32, u32),
+ /// The preferred depth for dumb ioctls
+ pub preferred_depth: u32,
+ /// An optional default fourcc format code to be preferred for clients.
+ pub preferred_fourcc: Option<u32>,
+}
diff --git a/rust/kernel/drm/mod.rs b/rust/kernel/drm/mod.rs
index 2c12dbd181997..049ae675cb9b1 100644
--- a/rust/kernel/drm/mod.rs
+++ b/rust/kernel/drm/mod.rs
@@ -8,3 +8,4 @@
pub mod fourcc;
pub mod gem;
pub mod ioctl;
+pub mod kms;
--
2.48.1
