On 3/7/23 11:25, Asahi Lina wrote:
DRM drivers need to be able to declare which driver-specific ioctls they
support. This abstraction adds the required types and a helper macro to
generate the ioctl definition inside the DRM driver.
Note that this macro is not usable until further bits of the
abstraction are in place (but it will not fail to compile on its own, if
not called).
Signed-off-by: Asahi Lina <lina@xxxxxxxxxxxxx>
---
drivers/gpu/drm/Kconfig | 7 ++
rust/bindings/bindings_helper.h | 2 +
rust/kernel/drm/ioctl.rs | 147 ++++++++++++++++++++++++++++++++++++++++
rust/kernel/drm/mod.rs | 5 ++
rust/kernel/lib.rs | 2 +
5 files changed, 163 insertions(+)
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index dc0f94f02a82..dab8f0f9aa96 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -27,6 +27,13 @@ menuconfig DRM
details. You should also select and configure AGP
(/dev/agpgart) support if it is available for your platform.
[...]
+
+/// Declare the DRM ioctls for a driver.
+///
+/// Each entry in the list should have the form:
+///
+/// `(ioctl_number, argument_type, flags, user_callback),`
+///
+/// `argument_type` is the type name within the `bindings` crate.
+/// `user_callback` should have the following prototype:
+///
+/// ```
+/// fn foo(device: &kernel::drm::device::Device<Self>,
+/// data: &mut bindings::argument_type,
+/// file: &kernel::drm::file::File<Self::File>,
+/// )
+/// ```
+/// where `Self` is the drm::drv::Driver implementation these ioctls are being declared within.
+///
+/// # Examples
+///
+/// ```
+/// kernel::declare_drm_ioctls! {
+/// (FOO_GET_PARAM, drm_foo_get_param, ioctl::RENDER_ALLOW, my_get_param_handler),
+/// }
+/// ```
+///
+#[macro_export]
+macro_rules! declare_drm_ioctls {
+ ( $(($cmd:ident, $struct:ident, $flags:expr, $func:expr)),* $(,)? ) => {
+ const IOCTLS: &'static [$crate::drm::ioctl::DrmIoctlDescriptor] = {
+ const _:() = {
+ let i: u32 = $crate::bindings::DRM_COMMAND_BASE;
+ // Assert that all the IOCTLs are in the right order and there are no gaps,
+ // and that the sizeof of the specified type is correct.
I believe that not necessarily the IOCTLs need to be in the right order and
with no gaps. For example, armada_drm.h has a gap in between 0x00 and
0x02 and exynos_drm.h also have gaps. Moreover, some drivers, like vgem and
virtgpu, start their IOCTLs with 0x01.
Best Regards,
- Maíra Canal
+ $(
+ let cmd: u32 = $crate::macros::concat_idents!($crate::bindings::DRM_IOCTL_, $cmd);
+ ::core::assert!(i == $crate::ioctl::_IOC_NR(cmd));
+ ::core::assert!(core::mem::size_of::<$crate::bindings::$struct>() == $crate::ioctl::_IOC_SIZE(cmd));
+ let i: u32 = i + 1;
+ )*
+ };
+
+ let ioctls = &[$(
+ $crate::bindings::drm_ioctl_desc {
+ cmd: $crate::macros::concat_idents!($crate::bindings::DRM_IOCTL_, $cmd) as u32,
+ func: {
+ #[allow(non_snake_case)]
+ unsafe extern "C" fn $cmd(
+ raw_dev: *mut $crate::bindings::drm_device,
+ raw_data: *mut ::core::ffi::c_void,
+ raw_file_priv: *mut $crate::bindings::drm_file,
+ ) -> core::ffi::c_int {
+ // SAFETY: We never drop this, and the DRM core ensures the device lives
+ // while callbacks are being called.
+ //
+ // FIXME: Currently there is nothing enforcing that the types of the
+ // dev/file match the current driver these ioctls are being declared
+ // for, and it's not clear how to enforce this within the type system.
+ let dev = ::core::mem::ManuallyDrop::new(unsafe {
+ $crate::drm::device::Device::from_raw(raw_dev)
+ });
+ // SAFETY: This is just the ioctl argument, which hopefully has the right type
+ // (we've done our best checking the size).
+ let data = unsafe { &mut *(raw_data as *mut $crate::bindings::$struct) };
+ // SAFETY: This is just the DRM file structure
+ let file = unsafe { $crate::drm::file::File::from_raw(raw_file_priv) };
+
+ match $func(&*dev, data, &file) {
+ Err(e) => e.to_kernel_errno(),
+ Ok(i) => i.try_into().unwrap_or(ERANGE.to_kernel_errno()),
+ }
+ }
+ Some($cmd)
+ },
+ flags: $flags,
+ name: $crate::c_str!(::core::stringify!($cmd)).as_char_ptr(),
+ }
+ ),*];
+ ioctls
+ };
+ };
+}
diff --git a/rust/kernel/drm/mod.rs b/rust/kernel/drm/mod.rs
new file mode 100644
index 000000000000..9ec6d7cbcaf3
--- /dev/null
+++ b/rust/kernel/drm/mod.rs
@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+
+//! DRM subsystem abstractions.
+
+pub mod ioctl;
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 7903490816bf..cb23d24c6718 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -37,6 +37,8 @@ mod build_assert;
pub mod delay;
pub mod device;
pub mod driver;
+#[cfg(CONFIG_RUST_DRM)]
+pub mod drm;
pub mod error;
pub mod io_buffer;
pub mod io_mem;
