rust: drm: Introduce the Tyr driver for Arm Mali GPUs

Add a Rust driver for ARM Mali CSF-based GPUs. It is a port of Panthor
and therefore exposes Panthor's uAPI and name to userspace, and the
product of a joint effort between Collabora, Arm and Google engineers.

The aim is to incrementally develop Tyr with the abstractions that are
currently available until it is consider to be in parity with Panthor
feature-wise.

The development of Tyr itself started in January, after a few failed
attempts of converting Panthor piecewise through a mix of Rust and C
code. There is a downstream branch that's much further ahead in terms of
capabilities than this initial patch.

The downstream code is capable of booting the MCU, doing sync VM_BINDS
through the work-in-progress GPUVM abstraction and also doing (trivial)
submits through Asahi's drm_scheduler and dma_fence abstractions. So
basically, most of what one would expect a modern GPU driver to do,
except for power management and some other very important adjacent
pieces. It is not at the point where submits can correctly deal with
dependencies, or at the point where it can rotate access to the GPU
hardware fairly through a software scheduler, but that is simply a
matter of writing more code.

This first patch, however, only implements a subset of the current
features available downstream, as the rest is not implementable without
pulling in even more abstractions. In particular, a lot of things depend
on properly mapping memory on a given VA range, which itself depends on
the GPUVM abstraction that is currently work-in-progress. For this
reason, we still cannot boot the MCU and thus, cannot do much for the
moment.

This constitutes a change in the overall strategy that we have been
using to develop Tyr so far. By submitting small parts of the driver
upstream iteratively, we aim to:

a) evolve together with Nova and rvkms, hopefully reducing regressions
due to upstream changes (that may break us because we were not there, in
the first place)

b) prove any work-in-progress abstractions by having them run on a real
driver and hardware and,

c) provide a reason to work on and review said abstractions by providing
a user, which would be tyr itself.

Despite its limited feature-set, we offer IGT tests. It is only tested
on the rk3588, so any other SoC is probably not going to work at all for
now.

The skeleton is basically taken from Nova and also
rust_platform_driver.rs.

Lastly, the name "Tyr" is inspired by Norse mythology, reflecting ARM's
tradition of naming their GPUs after Nordic mythological figures and
places.

Co-developed-by: Beata Michalska <beata.michalska@arm.com>
Signed-off-by: Beata Michalska <beata.michalska@arm.com>
Co-developed-by: Carsten Haitzler <carsten.haitzler@foss.arm.com>
Signed-off-by: Carsten Haitzler <carsten.haitzler@foss.arm.com>
Co-developed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://www.collabora.com/news-and-blog/news-and-events/introducing-tyr-a-new-rust-drm-driver.html
Signed-off-by: Daniel Almeida <daniel.almeida@collabora.com>
Acked-by: Boris Brezillon <boris.brezillon@collabora.com>
[aliceryhl: minor Kconfig update on apply]
[aliceryhl: s/drm::device::/drm::/]
Link: https://lore.kernel.org/r/20250910-tyr-v3-1-dba3bc2ae623@collabora.com
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>

Author: danielalmeida-collabora

MAINTAINERS

@@ -2086,6 +2086,19 @@ F:	Documentation/devicetree/bindings/gpu/arm,mali-valhall-csf.yaml
 F:	drivers/gpu/drm/panthor/
 F:	include/uapi/drm/panthor_drm.h
 
+ARM MALI TYR DRM DRIVER
+M:	Daniel Almeida <daniel.almeida@collabora.com>
+M:	Alice Ryhl <aliceryhl@google.com>
+L:	dri-devel@lists.freedesktop.org
+S:	Supported
+W:	https://rust-for-linux.com/tyr-gpu-driver
+W	https://drm.pages.freedesktop.org/maintainer-tools/drm-rust.html
+B:	https://gitlab.freedesktop.org/panfrost/linux/-/issues
+T:	git https://gitlab.freedesktop.org/drm/rust/kernel.git
+F:	Documentation/devicetree/bindings/gpu/arm,mali-valhall-csf.yaml
+F:	drivers/gpu/drm/tyr/
+F:	include/uapi/drm/panthor_drm.h
+
 ARM MALI-DP DRM DRIVER
 M:	Liviu Dudau <liviu.dudau@arm.com>
 S:	Supported

drivers/gpu/drm/Kconfig

@@ -396,6 +396,8 @@ source "drivers/gpu/drm/sprd/Kconfig"
 
 source "drivers/gpu/drm/imagination/Kconfig"
 
+source "drivers/gpu/drm/tyr/Kconfig"
+
 config DRM_HYPERV
 	tristate "DRM Support for Hyper-V synthetic video device"
 	depends on DRM && PCI && HYPERV

drivers/gpu/drm/Makefile

@@ -220,6 +220,7 @@ obj-$(CONFIG_DRM_VBOXVIDEO) += vboxvideo/
 obj-$(CONFIG_DRM_LIMA)  += lima/
 obj-$(CONFIG_DRM_PANFROST) += panfrost/
 obj-$(CONFIG_DRM_PANTHOR) += panthor/
+obj-$(CONFIG_DRM_TYR) += tyr/
 obj-$(CONFIG_DRM_ASPEED_GFX) += aspeed/
 obj-$(CONFIG_DRM_MCDE) += mcde/
 obj-$(CONFIG_DRM_TIDSS) += tidss/

drivers/gpu/drm/tyr/Kconfig

@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: GPL-2.0 or MIT
+
+config DRM_TYR
+	tristate "Tyr (Rust DRM support for ARM Mali CSF-based GPUs)"
+	depends on DRM=y
+	depends on RUST
+	depends on ARM || ARM64 || COMPILE_TEST
+	depends on !GENERIC_ATOMIC64  # for IOMMU_IO_PGTABLE_LPAE
+	default n
+	help
+	  Rust DRM driver for ARM Mali CSF-based GPUs.
+
+	  This driver is for Mali (or Immortalis) Valhall Gxxx GPUs.
+
+	  Note that the Mali-G68 and Mali-G78, while Valhall architecture, will
+	  be supported with the panfrost driver as they are not CSF GPUs.
+
+	  if M is selected, the module will be called tyr. This driver is work
+	  in progress and may not be functional.

drivers/gpu/drm/tyr/Makefile

@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0 or MIT
+
+obj-$(CONFIG_DRM_TYR) += tyr.o

drivers/gpu/drm/tyr/driver.rs

@@ -0,0 +1,205 @@
+// SPDX-License-Identifier: GPL-2.0 or MIT
+
+use kernel::c_str;
+use kernel::clk::Clk;
+use kernel::clk::OptionalClk;
+use kernel::device::Bound;
+use kernel::device::Core;
+use kernel::device::Device;
+use kernel::devres::Devres;
+use kernel::drm;
+use kernel::drm::ioctl;
+use kernel::new_mutex;
+use kernel::of;
+use kernel::platform;
+use kernel::prelude::*;
+use kernel::regulator;
+use kernel::regulator::Regulator;
+use kernel::sizes::SZ_2M;
+use kernel::sync::Arc;
+use kernel::sync::Mutex;
+use kernel::time;
+use kernel::types::ARef;
+
+use crate::file::File;
+use crate::gem::TyrObject;
+use crate::gpu;
+use crate::gpu::GpuInfo;
+use crate::regs;
+
+pub(crate) type IoMem = kernel::io::mem::IoMem<SZ_2M>;
+
+/// Convenience type alias for the DRM device type for this driver.
+pub(crate) type TyrDevice = drm::Device<TyrDriver>;
+
+#[pin_data(PinnedDrop)]
+pub(crate) struct TyrDriver {
+    device: ARef<TyrDevice>,
+}
+
+#[pin_data(PinnedDrop)]
+pub(crate) struct TyrData {
+    pub(crate) pdev: ARef<platform::Device>,
+
+    #[pin]
+    clks: Mutex<Clocks>,
+
+    #[pin]
+    regulators: Mutex<Regulators>,
+
+    /// Some information on the GPU.
+    ///
+    /// This is mainly queried by userspace, i.e.: Mesa.
+    pub(crate) gpu_info: GpuInfo,
+}
+
+// Both `Clk` and `Regulator` do not implement `Send` or `Sync`, but they
+// should. There are patches on the mailing list to address this, but they have
+// not landed yet.
+//
+// For now, add this workaround so that this patch compiles with the promise
+// that it will be removed in a future patch.
+//
+// SAFETY: This will be removed in a future patch.
+unsafe impl Send for TyrData {}
+// SAFETY: This will be removed in a future patch.
+unsafe impl Sync for TyrData {}
+
+fn issue_soft_reset(dev: &Device<Bound>, iomem: &Devres<IoMem>) -> Result {
+    regs::GPU_CMD.write(dev, iomem, regs::GPU_CMD_SOFT_RESET)?;
+
+    // TODO: We cannot poll, as there is no support in Rust currently, so we
+    // sleep. Change this when read_poll_timeout() is implemented in Rust.
+    kernel::time::delay::fsleep(time::Delta::from_millis(100));
+
+    if regs::GPU_IRQ_RAWSTAT.read(dev, iomem)? & regs::GPU_IRQ_RAWSTAT_RESET_COMPLETED == 0 {
+        dev_err!(dev, "GPU reset failed with errno\n");
+        dev_err!(
+            dev,
+            "GPU_INT_RAWSTAT is {}\n",
+            regs::GPU_IRQ_RAWSTAT.read(dev, iomem)?
+        );
+
+        return Err(EIO);
+    }
+
+    Ok(())
+}
+
+kernel::of_device_table!(
+    OF_TABLE,
+    MODULE_OF_TABLE,
+    <TyrDriver as platform::Driver>::IdInfo,
+    [
+        (of::DeviceId::new(c_str!("rockchip,rk3588-mali")), ()),
+        (of::DeviceId::new(c_str!("arm,mali-valhall-csf")), ())
+    ]
+);
+
+impl platform::Driver for TyrDriver {
+    type IdInfo = ();
+    const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
+
+    fn probe(
+        pdev: &platform::Device<Core>,
+        _info: Option<&Self::IdInfo>,
+    ) -> Result<Pin<KBox<Self>>> {
+        let core_clk = Clk::get(pdev.as_ref(), Some(c_str!("core")))?;
+        let stacks_clk = OptionalClk::get(pdev.as_ref(), Some(c_str!("stacks")))?;
+        let coregroup_clk = OptionalClk::get(pdev.as_ref(), Some(c_str!("coregroup")))?;
+
+        core_clk.prepare_enable()?;
+        stacks_clk.prepare_enable()?;
+        coregroup_clk.prepare_enable()?;
+
+        let mali_regulator = Regulator::<regulator::Enabled>::get(pdev.as_ref(), c_str!("mali"))?;
+        let sram_regulator = Regulator::<regulator::Enabled>::get(pdev.as_ref(), c_str!("sram"))?;
+
+        let request = pdev.io_request_by_index(0).ok_or(ENODEV)?;
+        let iomem = Arc::pin_init(request.iomap_sized::<SZ_2M>(), GFP_KERNEL)?;
+
+        issue_soft_reset(pdev.as_ref(), &iomem)?;
+        gpu::l2_power_on(pdev.as_ref(), &iomem)?;
+
+        let gpu_info = GpuInfo::new(pdev.as_ref(), &iomem)?;
+        gpu_info.log(pdev);
+
+        let platform: ARef<platform::Device> = pdev.into();
+
+        let data = try_pin_init!(TyrData {
+                pdev: platform.clone(),
+                clks <- new_mutex!(Clocks {
+                    core: core_clk,
+                    stacks: stacks_clk,
+                    coregroup: coregroup_clk,
+                }),
+                regulators <- new_mutex!(Regulators {
+                    mali: mali_regulator,
+                    sram: sram_regulator,
+                }),
+                gpu_info,
+        });
+
+        let tdev: ARef<TyrDevice> = drm::Device::new(pdev.as_ref(), data)?;
+        drm::driver::Registration::new_foreign_owned(&tdev, pdev.as_ref(), 0)?;
+
+        let driver = KBox::pin_init(try_pin_init!(TyrDriver { device: tdev }), GFP_KERNEL)?;
+
+        // We need this to be dev_info!() because dev_dbg!() does not work at
+        // all in Rust for now, and we need to see whether probe succeeded.
+        dev_info!(pdev.as_ref(), "Tyr initialized correctly.\n");
+        Ok(driver)
+    }
+}
+
+#[pinned_drop]
+impl PinnedDrop for TyrDriver {
+    fn drop(self: Pin<&mut Self>) {}
+}
+
+#[pinned_drop]
+impl PinnedDrop for TyrData {
+    fn drop(self: Pin<&mut Self>) {
+        // TODO: the type-state pattern for Clks will fix this.
+        let clks = self.clks.lock();
+        clks.core.disable_unprepare();
+        clks.stacks.disable_unprepare();
+        clks.coregroup.disable_unprepare();
+    }
+}
+
+// We need to retain the name "panthor" to achieve drop-in compatibility with
+// the C driver in the userspace stack.
+const INFO: drm::DriverInfo = drm::DriverInfo {
+    major: 1,
+    minor: 5,
+    patchlevel: 0,
+    name: c_str!("panthor"),
+    desc: c_str!("ARM Mali Tyr DRM driver"),
+};
+
+#[vtable]
+impl drm::Driver for TyrDriver {
+    type Data = TyrData;
+    type File = File;
+    type Object = drm::gem::Object<TyrObject>;
+
+    const INFO: drm::DriverInfo = INFO;
+
+    kernel::declare_drm_ioctls! {
+        (PANTHOR_DEV_QUERY, drm_panthor_dev_query, ioctl::RENDER_ALLOW, File::dev_query),
+    }
+}
+
+#[pin_data]
+struct Clocks {
+    core: Clk,
+    stacks: OptionalClk,
+    coregroup: OptionalClk,
+}
+
+#[pin_data]
+struct Regulators {
+    mali: Regulator<regulator::Enabled>,
+    sram: Regulator<regulator::Enabled>,
+}

drivers/gpu/drm/tyr/file.rs

@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0 or MIT
+
+use kernel::drm;
+use kernel::prelude::*;
+use kernel::uaccess::UserSlice;
+use kernel::uapi;
+
+use crate::driver::TyrDevice;
+use crate::TyrDriver;
+
+#[pin_data]
+pub(crate) struct File {}
+
+/// Convenience type alias for our DRM `File` type
+pub(crate) type DrmFile = drm::file::File<File>;
+
+impl drm::file::DriverFile for File {
+    type Driver = TyrDriver;
+
+    fn open(_dev: &drm::Device<Self::Driver>) -> Result<Pin<KBox<Self>>> {
+        KBox::try_pin_init(try_pin_init!(Self {}), GFP_KERNEL)
+    }
+}
+
+impl File {
+    pub(crate) fn dev_query(
+        tdev: &TyrDevice,
+        devquery: &mut uapi::drm_panthor_dev_query,
+        _file: &DrmFile,
+    ) -> Result<u32> {
+        if devquery.pointer == 0 {
+            match devquery.type_ {
+                uapi::drm_panthor_dev_query_type_DRM_PANTHOR_DEV_QUERY_GPU_INFO => {
+                    devquery.size = core::mem::size_of_val(&tdev.gpu_info) as u32;
+                    Ok(0)
+                }
+                _ => Err(EINVAL),
+            }
+        } else {
+            match devquery.type_ {
+                uapi::drm_panthor_dev_query_type_DRM_PANTHOR_DEV_QUERY_GPU_INFO => {
+                    let mut writer = UserSlice::new(
+                        UserPtr::from_addr(devquery.pointer as usize),
+                        devquery.size as usize,
+                    )
+                    .writer();
+
+                    writer.write(&tdev.gpu_info)?;
+
+                    Ok(0)
+                }
+                _ => Err(EINVAL),
+            }
+        }
+    }
+}

drivers/gpu/drm/tyr/gem.rs

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0 or MIT
+
+use crate::driver::TyrDevice;
+use crate::driver::TyrDriver;
+use kernel::drm::gem;
+use kernel::prelude::*;
+
+/// GEM Object inner driver data
+#[pin_data]
+pub(crate) struct TyrObject {}
+
+impl gem::DriverObject for TyrObject {
+    type Driver = TyrDriver;
+
+    fn new(_dev: &TyrDevice, _size: usize) -> impl PinInit<Self, Error> {
+        try_pin_init!(TyrObject {})
+    }
+}