Skip to contentSkip to conversation

gpu: nova-core: add initial driver stub

PATCH In review Danilo Krummrich 6 participants 9 messages Feb 9, 2025 – Feb 13, 2025

Subsystems (8)
lore
Share & tools
lore

Danilo Krummrich

author maintainer
#0 lore raw

PATCH v3 1/2 gpu: nova-core: add initial driver stub

Add the initial nova-core driver stub.

nova-core is intended to serve as a common base for nova-drm (the corresponding DRM driver) and the vGPU manager VFIO driver, serving as a hard- and firmware abstraction layer for GSP-based NVIDIA GPUs.

The Nova project, including nova-core and nova-drm, in the long term, is intended to serve as the successor of Nouveau for all GSP-based GPUs.

The motivation for both, starting a successor project for Nouveau and doing so using the Rust programming language, is documented in detail through a previous post on the mailing list [1], an LWN article [2] and a talk from LPC '24.

In order to avoid the chicken and egg problem to require a user to upstream Rust abstractions, but at the same time require the Rust abstractions to implement the driver, nova-core kicks off as a driver stub and is subsequently developed upstream.

---
Changes in v3:
- impl TryFrom<u32> for Chipset
- add Chipset::arch()
- initialize revision from Boot0
- in Firmware, eliminate repeating code pattern using a closure (thanks to Alexandre)
- use #[expect(dead_code)] for Firmware

Changes in v2:
- Fix module name in Kconfig description. (John)
- Expand Kconfig description a bit. (John)
- Expand name for PCI BAR0 region.
- Do not store / print boot0 raw register value. (John)
- Rename CardType to Architecture, rename enum names to represent the architecture name and adjust enum values according to the register definition. (John)
- Add an abstraction for register accesses.
- Print chipset, architecture and revision.
- Load bootloader firmware. (Timur)

---
 MAINTAINERS                        |  10 ++
 drivers/gpu/Makefile               |   1 +
 drivers/gpu/nova-core/Kconfig      |  14 +++
 drivers/gpu/nova-core/Makefile     |   3 +
 drivers/gpu/nova-core/driver.rs    |  47 +++++++
 drivers/gpu/nova-core/gpu.rs       | 189 +++++++++++++++++++++++++++++
 drivers/gpu/nova-core/nova_core.rs |  15 +++
 drivers/gpu/nova-core/regs.rs      |  56 +++++++++
 drivers/video/Kconfig              |   1 +
 9 files changed, 336 insertions(+)
 create mode 100644 drivers/gpu/nova-core/Kconfig
 create mode 100644 drivers/gpu/nova-core/Makefile
 create mode 100644 drivers/gpu/nova-core/driver.rs
 create mode 100644 drivers/gpu/nova-core/gpu.rs
 create mode 100644 drivers/gpu/nova-core/nova_core.rs
 create mode 100644 drivers/gpu/nova-core/regs.rs
MAINTAINERS +10 -0
index 25c86f47353d..5d5b7ed7da9e 100644
@@ -7446,6 +7446,16 @@ T:	git https://gitlab.freedesktop.org/drm/nouveau.git
 F:	drivers/gpu/drm/nouveau/
 F:	include/uapi/drm/nouveau_drm.h
 
+CORE DRIVER FOR NVIDIA GPUS [RUST]
+M:	Danilo Krummrich <[email protected]>
+L:	[email protected]
+S:	Supported
+Q:	https://patchwork.freedesktop.org/project/nouveau/
+B:	https://gitlab.freedesktop.org/drm/nova/-/issues
+C:	irc://irc.oftc.net/nouveau
+T:	git https://gitlab.freedesktop.org/drm/nova.git nova-next
+F:	drivers/gpu/nova-core/
+
 DRM DRIVER FOR OLIMEX LCD-OLINUXINO PANELS
 M:	Stefan Mavrodiev <[email protected]>
 S:	Maintained
drivers/gpu/Makefile +1 -0
index 8997f0096545..36a54d456630 100644
@@ -5,3 +5,4 @@
 obj-y			+= host1x/ drm/ vga/
 obj-$(CONFIG_IMX_IPUV3_CORE)	+= ipu-v3/
 obj-$(CONFIG_TRACE_GPU_MEM)		+= trace/
+obj-$(CONFIG_NOVA_CORE)		+= nova-core/
drivers/gpu/nova-core/Kconfig new file +14 -0
new file mode 100644
index 000000000000..ad0c06756516
@@ -0,0 +1,14 @@
+config NOVA_CORE
+	tristate "Nova Core GPU driver"
+	depends on PCI
+	depends on RUST
+	depends on RUST_FW_LOADER_ABSTRACTIONS
+	default n
+	help
+	  Choose this if you want to build the Nova Core driver for Nvidia
+	  GPUs based on the GPU System Processor (GSP). This is true for Turing
+	  and later GPUs.
+
+	  This driver is work in progress and may not be functional.
+
+	  If M is selected, the module will be called nova_core.
drivers/gpu/nova-core/Makefile new file +3 -0
new file mode 100644
index 000000000000..2d78c50126e1
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_NOVA_CORE) += nova_core.o
drivers/gpu/nova-core/driver.rs new file +47 -0

47 lines not on this page · raw message

drivers/gpu/nova-core/gpu.rs new file +189 -0

189 lines not on this page · raw message

drivers/gpu/nova-core/nova_core.rs new file +15 -0
new file mode 100644
index 000000000000..5d0230042793
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Nova Core GPU Driver
+
+mod driver;
+mod gpu;
+mod regs;
+
+kernel::module_pci_driver! {
+    type: driver::NovaCore,
+    name: "NovaCore",
+    author: "Danilo Krummrich",
+    description: "Nova Core GPU driver",
+    license: "GPL v2",
+}
drivers/gpu/nova-core/regs.rs new file +56 -0

56 lines not on this page · raw message

drivers/video/Kconfig +1 -0
index 44c9ef1435a2..5df981920a94 100644
@@ -39,6 +39,7 @@ source "drivers/gpu/vga/Kconfig"
 
 source "drivers/gpu/host1x/Kconfig"
 source "drivers/gpu/ipu-v3/Kconfig"
+source "drivers/gpu/nova-core/Kconfig"
 
 source "drivers/gpu/drm/Kconfig"
 

base-commit: 9946eaf552b194bb352c2945b54ff98c8193b3f1

Signature · 1 line
2.48.1
author maintainer
#1 lore raw

PATCH v3 2/2 gpu: nova-core: add initial documentation

Add the initial documentation of the Nova project.

The initial project documentation consists out of a brief introduction of the project, as well as project guidelines both general and nova-core specific and a task list for nova-core specifically.

The task list is divided into tasks for general Rust infrastructure required by the project, tasks regarding GSP enablement and firmware abstraction, general GPU driver tasks as well as tasks related to external API design and test infrastructure.

---
Changes in v3:
- Replace some Rust specific rules with links to existing R4L documentation.
- Link in R4L submit checklist.
- Update task entry "Page abstraction for foreign pages" with Lina's work.

Changes in v2:
- Add task "Generic register abstraction".
- Change complexity of "Debugfs abstractions".

---
 Documentation/gpu/drivers.rst              |   1 +
 Documentation/gpu/nova/core/guidelines.rst |  24 ++
 Documentation/gpu/nova/core/todo.rst       | 446 +++++++++++++++++++++
 Documentation/gpu/nova/guidelines.rst      |  69 ++++
 Documentation/gpu/nova/index.rst           |  30 ++
 MAINTAINERS                                |   1 +
 6 files changed, 571 insertions(+)
 create mode 100644 Documentation/gpu/nova/core/guidelines.rst
 create mode 100644 Documentation/gpu/nova/core/todo.rst
 create mode 100644 Documentation/gpu/nova/guidelines.rst
 create mode 100644 Documentation/gpu/nova/index.rst
Documentation/gpu/drivers.rst +1 -0
index 1f17ad0790d7..7c2c5dcb5fd4 100644
@@ -24,6 +24,7 @@ GPU Driver Documentation
    panfrost
    panthor
    zynqmp
+   nova/index
 
 .. only::  subproject and html
 
Documentation/gpu/nova/core/guidelines.rst new file +24 -0
new file mode 100644
index 000000000000..a389d65d7982
@@ -0,0 +1,24 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+==========
+Guidelines
+==========
+
+This documents contains the guidelines for nova-core. Additionally, all common
+guidelines of the Nova project do apply.
+
+Driver API
+==========
+
+One main purpose of nova-core is to implement the abstraction around the
+firmware interface of GSP and provide a firmware (version) independent API for
+2nd level drivers, such as nova-drm or the vGPU manager VFIO driver.
+
+Therefore, it is not permitted to leak firmware (version) specifics, through the
+driver API, to 2nd level drivers.
+
+Acceptance Criteria
+===================
+
+- To the extend possible, patches submitted to nova-core must be tested for
+  regressions with all 2nd level drivers.
Documentation/gpu/nova/core/todo.rst new file +446 -0

446 lines not on this page · raw message

Documentation/gpu/nova/guidelines.rst new file +69 -0

69 lines not on this page · raw message

Documentation/gpu/nova/index.rst new file +30 -0
new file mode 100644
index 000000000000..2701b3f4af35
@@ -0,0 +1,30 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+=======================
+nova NVIDIA GPU drivers
+=======================
+
+The nova driver project consists out of two separate drivers nova-core and
+nova-drm and intends to supersede the nouveau driver for NVIDIA GPUs based on
+the GPU System Processor (GSP).
+
+The following documents apply to both nova-core and nova-drm.
+
+.. toctree::
+   :titlesonly:
+
+   guidelines
+
+nova-core
+=========
+
+The nova-core driver is the core driver for NVIDIA GPUs based on GSP. nova-core,
+as the 1st level driver, provides an abstraction around the GPUs hard- and
+firmware interfaces providing a common base for 2nd level drivers, such as the
+vGPU manager VFIO driver and the nova-drm driver.
+
+.. toctree::
+   :titlesonly:
+
+   core/guidelines
+   core/todo
MAINTAINERS +1 -0
index 5d5b7ed7da9e..ed618e8757a5 100644
@@ -7454,6 +7454,7 @@ Q:	https://patchwork.freedesktop.org/project/nouveau/
 B:	https://gitlab.freedesktop.org/drm/nova/-/issues
 C:	irc://irc.oftc.net/nouveau
 T:	git https://gitlab.freedesktop.org/drm/nova.git nova-next
+F:	Documentation/gpu/nova/
 F:	drivers/gpu/nova-core/
 
 DRM DRIVER FOR OLIMEX LCD-OLINUXINO PANELS
Signature · 1 line
2.48.1
#2 lore raw

Re: [PATCH v3 2/2] gpu: nova-core: add initial documentation

On Sun, Feb 09, 2025 at 06:30:25PM +0100, Danilo Krummrich wrote:

[...]

Quoted 4 lines
Documentation/gpu/nova/core/todo.rst new file +4 -0
+FromPrimitive API
+-----------------
+
+Sometimes the need arises to convert a number to a value of an enum or a

Documentation/gpu/nova/core/todo.rst line 36

Quoted 10 lines
Documentation/gpu/nova/core/todo.rst new file +10 -0
+structure.
+
+A good example from nova-core would be the ``Chipset`` enum type, which defines
+the value ``AD102``. When probing the GPU the value ``0x192`` can be read from a
+certain register indication the chipset AD102. Hence, the enum value ``AD102``
+should be derived from the number ``0x192``. Currently, nova-core uses a custom
+implementation (``Chipset::from_u32`` for this.
+
+Instead, it would be desirable to have something like the ``FromPrimitive``
+trait [1] from the num crate.

I took a quick look at this, mainly to get more up to speed on Rust macros.

It seemed to me that bulk of the work here is actually in getting enough functionality added to rust/macros/quote.rs to make writing procedural macros pleasant. That seemed reasonably involved (probably beyond beginner level) and not the most pressing thing so I'm not currently looking at it, but thought I'd drop this note here in case it's useful for anyone else that is/wants to take a look.

- Alistair

Quoted 536 lines
Documentation/gpu/nova/core/todo.rst new file +409 -0
+Having this generalization also helps with implementing a generic macro that
+automatically generates the corresponding mappings between a value and a number.
+
+| Complexity: Beginner
+| Link: https://docs.rs/num/latest/num/trait.FromPrimitive.html
+
+Generic register abstraction
+----------------------------
+
+Work out how register constants and structures can be automatically generated
+through generalized macros.
+
+Example:
+
+.. code-block:: rust
+
+	register!(BOOT0, 0x0, u32, pci::Bar<SIZE>, Fields [
+	   MINOR_REVISION(3:0, RO),
+	   MAJOR_REVISION(7:4, RO),
+	   REVISION(7:0, RO), // Virtual register combining major and minor rev.
+	])
+
+This could expand to something like:
+
+.. code-block:: rust
+
+	const BOOT0_OFFSET: usize = 0x00000000;
+	const BOOT0_MINOR_REVISION_SHIFT: u8 = 0;
+	const BOOT0_MINOR_REVISION_MASK: u32 = 0x0000000f;
+	const BOOT0_MAJOR_REVISION_SHIFT: u8 = 4;
+	const BOOT0_MAJOR_REVISION_MASK: u32 = 0x000000f0;
+	const BOOT0_REVISION_SHIFT: u8 = BOOT0_MINOR_REVISION_SHIFT;
+	const BOOT0_REVISION_MASK: u32 = BOOT0_MINOR_REVISION_MASK | BOOT0_MAJOR_REVISION_MASK;
+
+	struct Boot0(u32);
+
+	impl Boot0 {
+	   #[inline]
+	   fn read(bar: &RevocableGuard<'_, pci::Bar<SIZE>>) -> Self {
+	      Self(bar.readl(BOOT0_OFFSET))
+	   }
+
+	   #[inline]
+	   fn minor_revision(&self) -> u32 {
+	      (self.0 & BOOT0_MINOR_REVISION_MASK) >> BOOT0_MINOR_REVISION_SHIFT
+	   }
+
+	   #[inline]
+	   fn major_revision(&self) -> u32 {
+	      (self.0 & BOOT0_MAJOR_REVISION_MASK) >> BOOT0_MAJOR_REVISION_SHIFT
+	   }
+
+	   #[inline]
+	   fn revision(&self) -> u32 {
+	      (self.0 & BOOT0_REVISION_MASK) >> BOOT0_REVISION_SHIFT
+	   }
+	}
+
+Usage:
+
+.. code-block:: rust
+
+	let bar = bar.try_access().ok_or(ENXIO)?;
+
+	let boot0 = Boot0::read(&bar);
+	pr_info!("Revision: {}\n", boot0.revision());
+
+| Complexity: Advanced
+
+Delay / Sleep abstractions
+--------------------------
+
+Rust abstractions for the kernel's delay() and sleep() functions.
+
+There is some ongoing work from FUJITA Tomonori [1], which has not seen any updates
+since Oct. 24.
+
+| Complexity: Beginner
+| Link: https://lore.kernel.org/netdev/[email protected]/ [1]
+
+IRQ abstractions
+----------------
+
+Rust abstractions for IRQ handling.
+
+There is active ongoing work from Daniel Almeida [1] for the "core" abstractions
+to request IRQs.
+
+Besides optional review and testing work, the required ``pci::Device`` code
+around those core abstractions needs to be worked out.
+
+| Complexity: Intermediate
+| Link: https://lore.kernel.org/lkml/[email protected]/ [1]
+| Contact: Daniel Almeida
+
+Page abstraction for foreign pages
+----------------------------------
+
+Rust abstractions for pages not created by the Rust page abstraction without
+direct ownership.
+
+There is active onging work from Abdiel Janulgue [1] and Lina [2].
+
+| Complexity: Advanced
+| Link: https://lore.kernel.org/linux-mm/[email protected]/ [1]
+| Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
+
+Scatterlist / sg_table abstractions
+-----------------------------------
+
+Rust abstractions for scatterlist / sg_table.
+
+There is preceding work from Abdiel Janulgue, which hasn't made it to the
+mailing list yet.
+
+| Complexity: Intermediate
+| Contact: Abdiel Janulgue
+
+ELF utils
+---------
+
+Rust implementation of ELF header representation to retrieve section header
+tables, names, and data from an ELF-formatted images.
+
+There is preceding work from Abdiel Janulgue, which hasn't made it to the
+mailing list yet.
+
+| Complexity: Beginner
+| Contact: Abdiel Janulgue
+
+PCI MISC APIs
+-------------
+
+Extend the existing PCI device / driver abstractions by SR-IOV, config space,
+capability, MSI API abstractions.
+
+| Complexity: Beginner
+
+Auxiliary bus abstractions
+--------------------------
+
+Rust abstraction for the auxiliary bus APIs.
+
+This is needed to connect nova-core to the nova-drm driver.
+
+| Complexity: Intermediate
+
+Debugfs abstractions
+--------------------
+
+Rust abstraction for debugfs APIs.
+
+| Reference: Export GSP log buffers
+| Complexity: Intermediate
+
+Vec extensions
+--------------
+
+Implement ``Vec::truncate`` and ``Vec::resize``.
+
+Currently this is used for some experimental code to parse the vBIOS.
+
+| Reference vBIOS support
+| Complexity: Beginner
+
+GPU (general)
+=============
+
+Parse firmware headers
+----------------------
+
+Parse ELF headers from the firmware files loaded from the filesystem.
+
+| Reference: ELF utils
+| Complexity: Beginner
+| Contact: Abdiel Janulgue
+
+Build radix3 page table
+-----------------------
+
+Build the radix3 page table to map the firmware.
+
+| Complexity: Intermediate
+| Contact: Abdiel Janulgue
+
+vBIOS support
+-------------
+
+Parse the vBIOS and probe the structures required for driver initialization.
+
+| Contact: Dave Airlie
+| Reference: Vec extensions
+| Complexity: Intermediate
+
+Initial Devinit support
+-----------------------
+
+Implement BIOS Device Initialization, i.e. memory sizing, waiting, PLL
+configuration.
+
+| Contact: Dave Airlie
+| Complexity: Beginner
+
+Boot Falcon controller
+----------------------
+
+Infrastructure to load and execute falcon (sec2) firmware images; handle the
+GSP falcon processor and fwsec loading.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+GPU Timer support
+-----------------
+
+Support for the GPU's internal timer peripheral.
+
+| Complexity: Beginner
+| Contact: Dave Airlie
+
+MMU / PT management
+-------------------
+
+Work out the architecture for MMU / page table management.
+
+We need to consider that nova-drm will need rather fine-grained control,
+especially in terms of locking, in order to be able to implement asynchronous
+Vulkan queues.
+
+While generally sharing the corresponding code is desirable, it needs to be
+evaluated how (and if at all) sharing the corresponding code is expedient.
+
+| Complexity: Expert
+
+VRAM memory allocator
+---------------------
+
+Investigate options for a VRAM memory allocator.
+
+Some possible options:
+  - Rust abstractions for
+    - RB tree (interval tree) / drm_mm
+    - maple_tree
+  - native Rust collections
+
+| Complexity: Advanced
+
+Instance Memory
+---------------
+
+Implement support for instmem (bar2) used to store page tables.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+GPU System Processor (GSP)
+==========================
+
+Export GSP log buffers
+----------------------
+
+Recent patches from Timur Tabi [1] added support to expose GSP-RM log buffers
+(even after failure to probe the driver) through debugfs.
+
+This is also an interesting feature for nova-core, especially in the early days.
+
+| Link: https://lore.kernel.org/nouveau/[email protected]/ [1]
+| Reference: Debugfs abstractions
+| Complexity: Intermediate
+
+GSP firmware abstraction
+------------------------
+
+The GSP-RM firmware API is unstable and may incompatibly change from version to
+version, in terms of data structures and semantics.
+
+This problem is one of the big motivations for using Rust for nova-core, since
+it turns out that Rust's procedural macro feature provides a rather elegant way
+to address this issue:
+
+1. generate Rust structures from the C headers in a separate namespace per version
+2. build abstraction structures (within a generic namespace) that implement the
+   firmware interfaces; annotate the differences in implementation with version
+   identifiers
+3. use a procedural macro to generate the actual per version implementation out
+   of this abstraction
+4. instantiate the correct version type one on runtime (can be sure that all
+   have the same interface because it's defined by a common trait)
+
+There is a PoC implementation of this pattern, in the context of the nova-core
+PoC driver.
+
+This task aims at refining the feature and ideally generalize it, to be usable
+by other drivers as well.
+
+| Complexity: Expert
+
+GSP message queue
+-----------------
+
+Implement low level GSP message queue (command, status) for communication
+between the kernel driver and GSP.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+Bootstrap GSP
+-------------
+
+Call the boot firmware to boot the GSP processor; execute initial control
+messages.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+Client / Device APIs
+--------------------
+
+Implement the GSP message interface for client / device allocation and the
+corresponding client and device allocation APIs.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+Bar PDE handling
+----------------
+
+Synchronize page table handling for BARs between the kernel driver and GSP.
+
+| Complexity: Beginner
+| Contact: Dave Airlie
+
+FIFO engine
+-----------
+
+Implement support for the FIFO engine, i.e. the corresponding GSP message
+interface and provide an API for chid allocation and channel handling.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+GR engine
+---------
+
+Implement support for the graphics engine, i.e. the corresponding GSP message
+interface and provide an API for (golden) context creation and promotion.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+CE engine
+---------
+
+Implement support for the copy engine, i.e. the corresponding GSP message
+interface.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+VFN IRQ controller
+------------------
+
+Support for the VFN interrupt controller.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+External APIs
+=============
+
+nova-core base API
+------------------
+
+Work out the common pieces of the API to connect 2nd level drivers, i.e. vGPU
+manager and nova-drm.
+
+| Complexity: Advanced
+
+vGPU manager API
+----------------
+
+Work out the API parts required by the vGPU manager, which are not covered by
+the base API.
+
+| Complexity: Advanced
+
+nova-core C API
+---------------
+
+Implement a C wrapper for the APIs required by the vGPU manager driver.
+
+| Complexity: Intermediate
+
+Testing
+=======
+
+CI pipeline
+-----------
+
+Investigate option for continuous integration testing.
+
+This can go from as simple as running KUnit tests over running (graphics) CTS to
+booting up (multiple) guest VMs to test VFIO use-cases.
+
+It might also be worth to consider the introduction of a new test suite directly
+sitting on top of the uAPI for more targeted testing and debugging. There may be
+options for collaboration / shared code with the Mesa project.
+
+| Complexity: Advanced
Documentation/gpu/nova/guidelines.rst new file +69 -0
new file mode 100644
index 000000000000..13ab13984a18
@@ -0,0 +1,69 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+==========
+Guidelines
+==========
+
+This document describes the general project guidelines that apply to nova-core
+and nova-drm.
+
+Language
+========
+
+The Nova project uses the Rust programming language. In this context, all rules
+of the Rust for Linux project as documented in
+:doc:`../../rust/general-information` apply. Additionally, the following rules
+apply.
+
+- Unless technically necessary otherwise (e.g. uAPI), any driver code is written
+  in Rust.
+
+- Unless technically necessary, unsafe Rust code must be avoided. In case of
+  technical necessity, unsafe code should be isolated in a separate component
+  providing a safe API for other driver code to use.
+
+Style
+-----
+
+All rules of the Rust for Linux project as documented in
+:doc:`../../rust/coding-guidelines` apply.
+
+For a submit checklist, please also see the `Rust for Linux Submit checklist
+addendum <https://rust-for-linux.com/contributing#submit-checklist-addendum>`_.
+
+Documentation
+=============
+
+The availability of proper documentation is essential in terms of scalability,
+accessibility for new contributors and maintainability of a project in general,
+but especially for a driver running as complex hardware as Nova is targeting.
+
+Hence, adding documentation of any kind is very much encouraged by the project.
+
+Besides that, there are some minimum requirements.
+
+- Every non-private structure needs at least a brief doc comment explaining the
+  semantical sense of the structure, as well as potential locking and lifetime
+  requirements. It is encouraged to have the same minimum documentation for
+  non-trivial private structures.
+
+- uAPIs must be fully documented with kernel-doc comments; additionally, the
+  semantical behavior must be explained including potential special or corner
+  cases.
+
+- The APIs connecting the 1st level driver (nova-core) with 2nd level drivers
+  must be fully documented. This includes doc comments, potential locking and
+  lifetime requirements, as well as example code if applicable.
+
+- Abbreviations must be explained when introduced; terminology must be uniquely
+  defined.
+
+- Register addresses, layouts, shift values and masks must be defined properly;
+  unless obvious, the semantical sense must be documented. This only applies if
+  the author is able to obtain the corresponding information.
+
+Acceptance Criteria
+===================
+
+- Patches must only be applied if reviewed by at least one other person on the
+  mailing list; this also applies for maintainers.
Documentation/gpu/nova/index.rst new file +30 -0
new file mode 100644
index 000000000000..2701b3f4af35
@@ -0,0 +1,30 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+=======================
+nova NVIDIA GPU drivers
+=======================
+
+The nova driver project consists out of two separate drivers nova-core and
+nova-drm and intends to supersede the nouveau driver for NVIDIA GPUs based on
+the GPU System Processor (GSP).
+
+The following documents apply to both nova-core and nova-drm.
+
+.. toctree::
+   :titlesonly:
+
+   guidelines
+
+nova-core
+=========
+
+The nova-core driver is the core driver for NVIDIA GPUs based on GSP. nova-core,
+as the 1st level driver, provides an abstraction around the GPUs hard- and
+firmware interfaces providing a common base for 2nd level drivers, such as the
+vGPU manager VFIO driver and the nova-drm driver.
+
+.. toctree::
+   :titlesonly:
+
+   core/guidelines
+   core/todo
MAINTAINERS +1 -0
index 5d5b7ed7da9e..ed618e8757a5 100644
@@ -7454,6 +7454,7 @@ Q:	https://patchwork.freedesktop.org/project/nouveau/
 B:	https://gitlab.freedesktop.org/drm/nova/-/issues
 C:	irc://irc.oftc.net/nouveau
 T:	git https://gitlab.freedesktop.org/drm/nova.git nova-next
+F:	Documentation/gpu/nova/
 F:	drivers/gpu/nova-core/
 
 DRM DRIVER FOR OLIMEX LCD-OLINUXINO PANELS
Signature · 1 line
2.48.1
#3 lore raw

Re: [PATCH v3 2/2] gpu: nova-core: add initial documentation

Quoted 21 lines · Alistair Popple

On Sun, Feb 09, 2025 at 06:30:25PM +0100, Danilo Krummrich wrote:

[...]

Quoted 4 lines
Documentation/gpu/nova/core/todo.rst new file +4 -0
+FromPrimitive API
+-----------------
+
+Sometimes the need arises to convert a number to a value of an enum or a

Documentation/gpu/nova/core/todo.rst line 36

Quoted 10 lines
Documentation/gpu/nova/core/todo.rst new file +10 -0
+structure.
+
+A good example from nova-core would be the ``Chipset`` enum type, which defines
+the value ``AD102``. When probing the GPU the value ``0x192`` can be read from a
+certain register indication the chipset AD102. Hence, the enum value ``AD102``
+should be derived from the number ``0x192``. Currently, nova-core uses a custom
+implementation (``Chipset::from_u32`` for this.
+
+Instead, it would be desirable to have something like the ``FromPrimitive``
+trait [1] from the num crate.

I took a quick look at this, mainly to get more up to speed on Rust macros.

Quoted 6 lines

It seemed to me that bulk of the work here is actually in getting enough functionality added to rust/macros/quote.rs to make writing procedural macros pleasant. That seemed reasonably involved (probably beyond beginner level) and not the most pressing thing so I'm not currently looking at it, but thought I'd drop this note here in case it's useful for anyone else that is/wants to take a look.

We're already aware of this and actively working on a solution.

Note that we don't actually have to write this code ourselves, as it already exists in the user-space ecosystem in the form of the quote crate [1].
Also, since this is a dependency of the macros kernel crate, its fine to use user-space rust, since proc-macros end up as "compiler plugins", so they run on the host and not inside of the kernel that is being built (so they also have access to std).
The only problem is that we need access to quote and since we don't use cargo, it's not as easy as adding it as a dependency. Currently we're working on a solution that will give us not only the quote crate but also the syn crate [2] which will make building proc-macros feasible.

(Note that both crates are highly used in the Rust ecosystem and IIRC also the compiler depends on them. So it is not just any random Rust library that we would add to our dependencies.)

[1]: https://crates.io/crates/quote
[2]: https://crates.io/crates/syn

---
Cheers,
Benno

Quoted 539 lines

- Alistair

Quoted 536 lines
Documentation/gpu/nova/core/todo.rst new file +409 -0
+Having this generalization also helps with implementing a generic macro that
+automatically generates the corresponding mappings between a value and a number.
+
+| Complexity: Beginner
+| Link: https://docs.rs/num/latest/num/trait.FromPrimitive.html
+
+Generic register abstraction
+----------------------------
+
+Work out how register constants and structures can be automatically generated
+through generalized macros.
+
+Example:
+
+.. code-block:: rust
+
+	register!(BOOT0, 0x0, u32, pci::Bar<SIZE>, Fields [
+	   MINOR_REVISION(3:0, RO),
+	   MAJOR_REVISION(7:4, RO),
+	   REVISION(7:0, RO), // Virtual register combining major and minor rev.
+	])
+
+This could expand to something like:
+
+.. code-block:: rust
+
+	const BOOT0_OFFSET: usize = 0x00000000;
+	const BOOT0_MINOR_REVISION_SHIFT: u8 = 0;
+	const BOOT0_MINOR_REVISION_MASK: u32 = 0x0000000f;
+	const BOOT0_MAJOR_REVISION_SHIFT: u8 = 4;
+	const BOOT0_MAJOR_REVISION_MASK: u32 = 0x000000f0;
+	const BOOT0_REVISION_SHIFT: u8 = BOOT0_MINOR_REVISION_SHIFT;
+	const BOOT0_REVISION_MASK: u32 = BOOT0_MINOR_REVISION_MASK | BOOT0_MAJOR_REVISION_MASK;
+
+	struct Boot0(u32);
+
+	impl Boot0 {
+	   #[inline]
+	   fn read(bar: &RevocableGuard<'_, pci::Bar<SIZE>>) -> Self {
+	      Self(bar.readl(BOOT0_OFFSET))
+	   }
+
+	   #[inline]
+	   fn minor_revision(&self) -> u32 {
+	      (self.0 & BOOT0_MINOR_REVISION_MASK) >> BOOT0_MINOR_REVISION_SHIFT
+	   }
+
+	   #[inline]
+	   fn major_revision(&self) -> u32 {
+	      (self.0 & BOOT0_MAJOR_REVISION_MASK) >> BOOT0_MAJOR_REVISION_SHIFT
+	   }
+
+	   #[inline]
+	   fn revision(&self) -> u32 {
+	      (self.0 & BOOT0_REVISION_MASK) >> BOOT0_REVISION_SHIFT
+	   }
+	}
+
+Usage:
+
+.. code-block:: rust
+
+	let bar = bar.try_access().ok_or(ENXIO)?;
+
+	let boot0 = Boot0::read(&bar);
+	pr_info!("Revision: {}\n", boot0.revision());
+
+| Complexity: Advanced
+
+Delay / Sleep abstractions
+--------------------------
+
+Rust abstractions for the kernel's delay() and sleep() functions.
+
+There is some ongoing work from FUJITA Tomonori [1], which has not seen any updates
+since Oct. 24.
+
+| Complexity: Beginner
+| Link: https://lore.kernel.org/netdev/[email protected]/ [1]
+
+IRQ abstractions
+----------------
+
+Rust abstractions for IRQ handling.
+
+There is active ongoing work from Daniel Almeida [1] for the "core" abstractions
+to request IRQs.
+
+Besides optional review and testing work, the required ``pci::Device`` code
+around those core abstractions needs to be worked out.
+
+| Complexity: Intermediate
+| Link: https://lore.kernel.org/lkml/[email protected]/ [1]
+| Contact: Daniel Almeida
+
+Page abstraction for foreign pages
+----------------------------------
+
+Rust abstractions for pages not created by the Rust page abstraction without
+direct ownership.
+
+There is active onging work from Abdiel Janulgue [1] and Lina [2].
+
+| Complexity: Advanced
+| Link: https://lore.kernel.org/linux-mm/[email protected]/ [1]
+| Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
+
+Scatterlist / sg_table abstractions
+-----------------------------------
+
+Rust abstractions for scatterlist / sg_table.
+
+There is preceding work from Abdiel Janulgue, which hasn't made it to the
+mailing list yet.
+
+| Complexity: Intermediate
+| Contact: Abdiel Janulgue
+
+ELF utils
+---------
+
+Rust implementation of ELF header representation to retrieve section header
+tables, names, and data from an ELF-formatted images.
+
+There is preceding work from Abdiel Janulgue, which hasn't made it to the
+mailing list yet.
+
+| Complexity: Beginner
+| Contact: Abdiel Janulgue
+
+PCI MISC APIs
+-------------
+
+Extend the existing PCI device / driver abstractions by SR-IOV, config space,
+capability, MSI API abstractions.
+
+| Complexity: Beginner
+
+Auxiliary bus abstractions
+--------------------------
+
+Rust abstraction for the auxiliary bus APIs.
+
+This is needed to connect nova-core to the nova-drm driver.
+
+| Complexity: Intermediate
+
+Debugfs abstractions
+--------------------
+
+Rust abstraction for debugfs APIs.
+
+| Reference: Export GSP log buffers
+| Complexity: Intermediate
+
+Vec extensions
+--------------
+
+Implement ``Vec::truncate`` and ``Vec::resize``.
+
+Currently this is used for some experimental code to parse the vBIOS.
+
+| Reference vBIOS support
+| Complexity: Beginner
+
+GPU (general)
+=============
+
+Parse firmware headers
+----------------------
+
+Parse ELF headers from the firmware files loaded from the filesystem.
+
+| Reference: ELF utils
+| Complexity: Beginner
+| Contact: Abdiel Janulgue
+
+Build radix3 page table
+-----------------------
+
+Build the radix3 page table to map the firmware.
+
+| Complexity: Intermediate
+| Contact: Abdiel Janulgue
+
+vBIOS support
+-------------
+
+Parse the vBIOS and probe the structures required for driver initialization.
+
+| Contact: Dave Airlie
+| Reference: Vec extensions
+| Complexity: Intermediate
+
+Initial Devinit support
+-----------------------
+
+Implement BIOS Device Initialization, i.e. memory sizing, waiting, PLL
+configuration.
+
+| Contact: Dave Airlie
+| Complexity: Beginner
+
+Boot Falcon controller
+----------------------
+
+Infrastructure to load and execute falcon (sec2) firmware images; handle the
+GSP falcon processor and fwsec loading.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+GPU Timer support
+-----------------
+
+Support for the GPU's internal timer peripheral.
+
+| Complexity: Beginner
+| Contact: Dave Airlie
+
+MMU / PT management
+-------------------
+
+Work out the architecture for MMU / page table management.
+
+We need to consider that nova-drm will need rather fine-grained control,
+especially in terms of locking, in order to be able to implement asynchronous
+Vulkan queues.
+
+While generally sharing the corresponding code is desirable, it needs to be
+evaluated how (and if at all) sharing the corresponding code is expedient.
+
+| Complexity: Expert
+
+VRAM memory allocator
+---------------------
+
+Investigate options for a VRAM memory allocator.
+
+Some possible options:
+  - Rust abstractions for
+    - RB tree (interval tree) / drm_mm
+    - maple_tree
+  - native Rust collections
+
+| Complexity: Advanced
+
+Instance Memory
+---------------
+
+Implement support for instmem (bar2) used to store page tables.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+GPU System Processor (GSP)
+==========================
+
+Export GSP log buffers
+----------------------
+
+Recent patches from Timur Tabi [1] added support to expose GSP-RM log buffers
+(even after failure to probe the driver) through debugfs.
+
+This is also an interesting feature for nova-core, especially in the early days.
+
+| Link: https://lore.kernel.org/nouveau/[email protected]/ [1]
+| Reference: Debugfs abstractions
+| Complexity: Intermediate
+
+GSP firmware abstraction
+------------------------
+
+The GSP-RM firmware API is unstable and may incompatibly change from version to
+version, in terms of data structures and semantics.
+
+This problem is one of the big motivations for using Rust for nova-core, since
+it turns out that Rust's procedural macro feature provides a rather elegant way
+to address this issue:
+
+1. generate Rust structures from the C headers in a separate namespace per version
+2. build abstraction structures (within a generic namespace) that implement the
+   firmware interfaces; annotate the differences in implementation with version
+   identifiers
+3. use a procedural macro to generate the actual per version implementation out
+   of this abstraction
+4. instantiate the correct version type one on runtime (can be sure that all
+   have the same interface because it's defined by a common trait)
+
+There is a PoC implementation of this pattern, in the context of the nova-core
+PoC driver.
+
+This task aims at refining the feature and ideally generalize it, to be usable
+by other drivers as well.
+
+| Complexity: Expert
+
+GSP message queue
+-----------------
+
+Implement low level GSP message queue (command, status) for communication
+between the kernel driver and GSP.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+Bootstrap GSP
+-------------
+
+Call the boot firmware to boot the GSP processor; execute initial control
+messages.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+Client / Device APIs
+--------------------
+
+Implement the GSP message interface for client / device allocation and the
+corresponding client and device allocation APIs.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+Bar PDE handling
+----------------
+
+Synchronize page table handling for BARs between the kernel driver and GSP.
+
+| Complexity: Beginner
+| Contact: Dave Airlie
+
+FIFO engine
+-----------
+
+Implement support for the FIFO engine, i.e. the corresponding GSP message
+interface and provide an API for chid allocation and channel handling.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+GR engine
+---------
+
+Implement support for the graphics engine, i.e. the corresponding GSP message
+interface and provide an API for (golden) context creation and promotion.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+CE engine
+---------
+
+Implement support for the copy engine, i.e. the corresponding GSP message
+interface.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+VFN IRQ controller
+------------------
+
+Support for the VFN interrupt controller.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+External APIs
+=============
+
+nova-core base API
+------------------
+
+Work out the common pieces of the API to connect 2nd level drivers, i.e. vGPU
+manager and nova-drm.
+
+| Complexity: Advanced
+
+vGPU manager API
+----------------
+
+Work out the API parts required by the vGPU manager, which are not covered by
+the base API.
+
+| Complexity: Advanced
+
+nova-core C API
+---------------
+
+Implement a C wrapper for the APIs required by the vGPU manager driver.
+
+| Complexity: Intermediate
+
+Testing
+=======
+
+CI pipeline
+-----------
+
+Investigate option for continuous integration testing.
+
+This can go from as simple as running KUnit tests over running (graphics) CTS to
+booting up (multiple) guest VMs to test VFIO use-cases.
+
+It might also be worth to consider the introduction of a new test suite directly
+sitting on top of the uAPI for more targeted testing and debugging. There may be
+options for collaboration / shared code with the Mesa project.
+
+| Complexity: Advanced
Documentation/gpu/nova/guidelines.rst new file +69 -0
new file mode 100644
index 000000000000..13ab13984a18
@@ -0,0 +1,69 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+==========
+Guidelines
+==========
+
+This document describes the general project guidelines that apply to nova-core
+and nova-drm.
+
+Language
+========
+
+The Nova project uses the Rust programming language. In this context, all rules
+of the Rust for Linux project as documented in
+:doc:`../../rust/general-information` apply. Additionally, the following rules
+apply.
+
+- Unless technically necessary otherwise (e.g. uAPI), any driver code is written
+  in Rust.
+
+- Unless technically necessary, unsafe Rust code must be avoided. In case of
+  technical necessity, unsafe code should be isolated in a separate component
+  providing a safe API for other driver code to use.
+
+Style
+-----
+
+All rules of the Rust for Linux project as documented in
+:doc:`../../rust/coding-guidelines` apply.
+
+For a submit checklist, please also see the `Rust for Linux Submit checklist
+addendum <https://rust-for-linux.com/contributing#submit-checklist-addendum>`_.
+
+Documentation
+=============
+
+The availability of proper documentation is essential in terms of scalability,
+accessibility for new contributors and maintainability of a project in general,
+but especially for a driver running as complex hardware as Nova is targeting.
+
+Hence, adding documentation of any kind is very much encouraged by the project.
+
+Besides that, there are some minimum requirements.
+
+- Every non-private structure needs at least a brief doc comment explaining the
+  semantical sense of the structure, as well as potential locking and lifetime
+  requirements. It is encouraged to have the same minimum documentation for
+  non-trivial private structures.
+
+- uAPIs must be fully documented with kernel-doc comments; additionally, the
+  semantical behavior must be explained including potential special or corner
+  cases.
+
+- The APIs connecting the 1st level driver (nova-core) with 2nd level drivers
+  must be fully documented. This includes doc comments, potential locking and
+  lifetime requirements, as well as example code if applicable.
+
+- Abbreviations must be explained when introduced; terminology must be uniquely
+  defined.
+
+- Register addresses, layouts, shift values and masks must be defined properly;
+  unless obvious, the semantical sense must be documented. This only applies if
+  the author is able to obtain the corresponding information.
+
+Acceptance Criteria
+===================
+
+- Patches must only be applied if reviewed by at least one other person on the
+  mailing list; this also applies for maintainers.
Documentation/gpu/nova/index.rst new file +30 -0
new file mode 100644
index 000000000000..2701b3f4af35
@@ -0,0 +1,30 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+=======================
+nova NVIDIA GPU drivers
+=======================
+
+The nova driver project consists out of two separate drivers nova-core and
+nova-drm and intends to supersede the nouveau driver for NVIDIA GPUs based on
+the GPU System Processor (GSP).
+
+The following documents apply to both nova-core and nova-drm.
+
+.. toctree::
+   :titlesonly:
+
+   guidelines
+
+nova-core
+=========
+
+The nova-core driver is the core driver for NVIDIA GPUs based on GSP. nova-core,
+as the 1st level driver, provides an abstraction around the GPUs hard- and
+firmware interfaces providing a common base for 2nd level drivers, such as the
+vGPU manager VFIO driver and the nova-drm driver.
+
+.. toctree::
+   :titlesonly:
+
+   core/guidelines
+   core/todo
MAINTAINERS +1 -1
index 5d5b7ed7da9e..ed618e8757a5 100644
@@ -7454,6 +7454,7 @@ Q:	https://patchwork.freedesktop.org/project/nouveau/
 B:	https://gitlab.freedesktop.org/drm/nova/-/issues
 C:	irc://irc.oftc.net/nouveau
 T:	git https://gitlab.freedesktop.org/drm/nova.git nova-next
+F:	Documentation/gpu/nova/
 F:	drivers/gpu/nova-core/
 
 DRM DRIVER FOR OLIMEX LCD-OLINUXINO PANELS
--

2.48.1

#4 lore raw

Re: [PATCH v3 2/2] gpu: nova-core: add initial documentation

Quoted 22 lines · Benno Lossin
Quoted 21 lines · Alistair Popple

On Sun, Feb 09, 2025 at 06:30:25PM +0100, Danilo Krummrich wrote:

[...]

Quoted 4 lines
Documentation/gpu/nova/core/todo.rst new file +4 -0
+FromPrimitive API
+-----------------
+
+Sometimes the need arises to convert a number to a value of an enum or a

Documentation/gpu/nova/core/todo.rst line 36

Quoted 10 lines
Documentation/gpu/nova/core/todo.rst new file +10 -0
+structure.
+
+A good example from nova-core would be the ``Chipset`` enum type, which defines
+the value ``AD102``. When probing the GPU the value ``0x192`` can be read from a
+certain register indication the chipset AD102. Hence, the enum value ``AD102``
+should be derived from the number ``0x192``. Currently, nova-core uses a custom
+implementation (``Chipset::from_u32`` for this.
+
+Instead, it would be desirable to have something like the ``FromPrimitive``
+trait [1] from the num crate.

I took a quick look at this, mainly to get more up to speed on Rust macros.

Quoted 8 lines
Quoted 6 lines

It seemed to me that bulk of the work here is actually in getting enough functionality added to rust/macros/quote.rs to make writing procedural macros pleasant. That seemed reasonably involved (probably beyond beginner level) and not the most pressing thing so I'm not currently looking at it, but thought I'd drop this note here in case it's useful for anyone else that is/wants to take a look.

We're already aware of this and actively working on a solution.

Argh, great! Good to know.

Quoted 12 lines

Note that we don't actually have to write this code ourselves, as it already exists in the user-space ecosystem in the form of the quote crate [1].
Also, since this is a dependency of the macros kernel crate, its fine to use user-space rust, since proc-macros end up as "compiler plugins", so they run on the host and not inside of the kernel that is being built (so they also have access to std).
The only problem is that we need access to quote and since we don't use cargo, it's not as easy as adding it as a dependency. Currently we're working on a solution that will give us not only the quote crate but also the syn crate [2] which will make building proc-macros feasible.

Quoted 3 lines

(Note that both crates are highly used in the Rust ecosystem and IIRC also the compiler depends on them. So it is not just any random Rust library that we would add to our dependencies.)

Of course, I was wondering why they weren't already included so many thanks for filling me in on the background.

Quoted 547 lines

[1]: https://crates.io/crates/quote
[2]: https://crates.io/crates/syn

---
Cheers,
Benno

Quoted 539 lines

- Alistair

Quoted 536 lines
Documentation/gpu/nova/core/todo.rst new file +409 -0
+Having this generalization also helps with implementing a generic macro that
+automatically generates the corresponding mappings between a value and a number.
+
+| Complexity: Beginner
+| Link: https://docs.rs/num/latest/num/trait.FromPrimitive.html
+
+Generic register abstraction
+----------------------------
+
+Work out how register constants and structures can be automatically generated
+through generalized macros.
+
+Example:
+
+.. code-block:: rust
+
+	register!(BOOT0, 0x0, u32, pci::Bar<SIZE>, Fields [
+	   MINOR_REVISION(3:0, RO),
+	   MAJOR_REVISION(7:4, RO),
+	   REVISION(7:0, RO), // Virtual register combining major and minor rev.
+	])
+
+This could expand to something like:
+
+.. code-block:: rust
+
+	const BOOT0_OFFSET: usize = 0x00000000;
+	const BOOT0_MINOR_REVISION_SHIFT: u8 = 0;
+	const BOOT0_MINOR_REVISION_MASK: u32 = 0x0000000f;
+	const BOOT0_MAJOR_REVISION_SHIFT: u8 = 4;
+	const BOOT0_MAJOR_REVISION_MASK: u32 = 0x000000f0;
+	const BOOT0_REVISION_SHIFT: u8 = BOOT0_MINOR_REVISION_SHIFT;
+	const BOOT0_REVISION_MASK: u32 = BOOT0_MINOR_REVISION_MASK | BOOT0_MAJOR_REVISION_MASK;
+
+	struct Boot0(u32);
+
+	impl Boot0 {
+	   #[inline]
+	   fn read(bar: &RevocableGuard<'_, pci::Bar<SIZE>>) -> Self {
+	      Self(bar.readl(BOOT0_OFFSET))
+	   }
+
+	   #[inline]
+	   fn minor_revision(&self) -> u32 {
+	      (self.0 & BOOT0_MINOR_REVISION_MASK) >> BOOT0_MINOR_REVISION_SHIFT
+	   }
+
+	   #[inline]
+	   fn major_revision(&self) -> u32 {
+	      (self.0 & BOOT0_MAJOR_REVISION_MASK) >> BOOT0_MAJOR_REVISION_SHIFT
+	   }
+
+	   #[inline]
+	   fn revision(&self) -> u32 {
+	      (self.0 & BOOT0_REVISION_MASK) >> BOOT0_REVISION_SHIFT
+	   }
+	}
+
+Usage:
+
+.. code-block:: rust
+
+	let bar = bar.try_access().ok_or(ENXIO)?;
+
+	let boot0 = Boot0::read(&bar);
+	pr_info!("Revision: {}\n", boot0.revision());
+
+| Complexity: Advanced
+
+Delay / Sleep abstractions
+--------------------------
+
+Rust abstractions for the kernel's delay() and sleep() functions.
+
+There is some ongoing work from FUJITA Tomonori [1], which has not seen any updates
+since Oct. 24.
+
+| Complexity: Beginner
+| Link: https://lore.kernel.org/netdev/[email protected]/ [1]
+
+IRQ abstractions
+----------------
+
+Rust abstractions for IRQ handling.
+
+There is active ongoing work from Daniel Almeida [1] for the "core" abstractions
+to request IRQs.
+
+Besides optional review and testing work, the required ``pci::Device`` code
+around those core abstractions needs to be worked out.
+
+| Complexity: Intermediate
+| Link: https://lore.kernel.org/lkml/[email protected]/ [1]
+| Contact: Daniel Almeida
+
+Page abstraction for foreign pages
+----------------------------------
+
+Rust abstractions for pages not created by the Rust page abstraction without
+direct ownership.
+
+There is active onging work from Abdiel Janulgue [1] and Lina [2].
+
+| Complexity: Advanced
+| Link: https://lore.kernel.org/linux-mm/[email protected]/ [1]
+| Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
+
+Scatterlist / sg_table abstractions
+-----------------------------------
+
+Rust abstractions for scatterlist / sg_table.
+
+There is preceding work from Abdiel Janulgue, which hasn't made it to the
+mailing list yet.
+
+| Complexity: Intermediate
+| Contact: Abdiel Janulgue
+
+ELF utils
+---------
+
+Rust implementation of ELF header representation to retrieve section header
+tables, names, and data from an ELF-formatted images.
+
+There is preceding work from Abdiel Janulgue, which hasn't made it to the
+mailing list yet.
+
+| Complexity: Beginner
+| Contact: Abdiel Janulgue
+
+PCI MISC APIs
+-------------
+
+Extend the existing PCI device / driver abstractions by SR-IOV, config space,
+capability, MSI API abstractions.
+
+| Complexity: Beginner
+
+Auxiliary bus abstractions
+--------------------------
+
+Rust abstraction for the auxiliary bus APIs.
+
+This is needed to connect nova-core to the nova-drm driver.
+
+| Complexity: Intermediate
+
+Debugfs abstractions
+--------------------
+
+Rust abstraction for debugfs APIs.
+
+| Reference: Export GSP log buffers
+| Complexity: Intermediate
+
+Vec extensions
+--------------
+
+Implement ``Vec::truncate`` and ``Vec::resize``.
+
+Currently this is used for some experimental code to parse the vBIOS.
+
+| Reference vBIOS support
+| Complexity: Beginner
+
+GPU (general)
+=============
+
+Parse firmware headers
+----------------------
+
+Parse ELF headers from the firmware files loaded from the filesystem.
+
+| Reference: ELF utils
+| Complexity: Beginner
+| Contact: Abdiel Janulgue
+
+Build radix3 page table
+-----------------------
+
+Build the radix3 page table to map the firmware.
+
+| Complexity: Intermediate
+| Contact: Abdiel Janulgue
+
+vBIOS support
+-------------
+
+Parse the vBIOS and probe the structures required for driver initialization.
+
+| Contact: Dave Airlie
+| Reference: Vec extensions
+| Complexity: Intermediate
+
+Initial Devinit support
+-----------------------
+
+Implement BIOS Device Initialization, i.e. memory sizing, waiting, PLL
+configuration.
+
+| Contact: Dave Airlie
+| Complexity: Beginner
+
+Boot Falcon controller
+----------------------
+
+Infrastructure to load and execute falcon (sec2) firmware images; handle the
+GSP falcon processor and fwsec loading.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+GPU Timer support
+-----------------
+
+Support for the GPU's internal timer peripheral.
+
+| Complexity: Beginner
+| Contact: Dave Airlie
+
+MMU / PT management
+-------------------
+
+Work out the architecture for MMU / page table management.
+
+We need to consider that nova-drm will need rather fine-grained control,
+especially in terms of locking, in order to be able to implement asynchronous
+Vulkan queues.
+
+While generally sharing the corresponding code is desirable, it needs to be
+evaluated how (and if at all) sharing the corresponding code is expedient.
+
+| Complexity: Expert
+
+VRAM memory allocator
+---------------------
+
+Investigate options for a VRAM memory allocator.
+
+Some possible options:
+  - Rust abstractions for
+    - RB tree (interval tree) / drm_mm
+    - maple_tree
+  - native Rust collections
+
+| Complexity: Advanced
+
+Instance Memory
+---------------
+
+Implement support for instmem (bar2) used to store page tables.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+GPU System Processor (GSP)
+==========================
+
+Export GSP log buffers
+----------------------
+
+Recent patches from Timur Tabi [1] added support to expose GSP-RM log buffers
+(even after failure to probe the driver) through debugfs.
+
+This is also an interesting feature for nova-core, especially in the early days.
+
+| Link: https://lore.kernel.org/nouveau/[email protected]/ [1]
+| Reference: Debugfs abstractions
+| Complexity: Intermediate
+
+GSP firmware abstraction
+------------------------
+
+The GSP-RM firmware API is unstable and may incompatibly change from version to
+version, in terms of data structures and semantics.
+
+This problem is one of the big motivations for using Rust for nova-core, since
+it turns out that Rust's procedural macro feature provides a rather elegant way
+to address this issue:
+
+1. generate Rust structures from the C headers in a separate namespace per version
+2. build abstraction structures (within a generic namespace) that implement the
+   firmware interfaces; annotate the differences in implementation with version
+   identifiers
+3. use a procedural macro to generate the actual per version implementation out
+   of this abstraction
+4. instantiate the correct version type one on runtime (can be sure that all
+   have the same interface because it's defined by a common trait)
+
+There is a PoC implementation of this pattern, in the context of the nova-core
+PoC driver.
+
+This task aims at refining the feature and ideally generalize it, to be usable
+by other drivers as well.
+
+| Complexity: Expert
+
+GSP message queue
+-----------------
+
+Implement low level GSP message queue (command, status) for communication
+between the kernel driver and GSP.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+Bootstrap GSP
+-------------
+
+Call the boot firmware to boot the GSP processor; execute initial control
+messages.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+Client / Device APIs
+--------------------
+
+Implement the GSP message interface for client / device allocation and the
+corresponding client and device allocation APIs.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+Bar PDE handling
+----------------
+
+Synchronize page table handling for BARs between the kernel driver and GSP.
+
+| Complexity: Beginner
+| Contact: Dave Airlie
+
+FIFO engine
+-----------
+
+Implement support for the FIFO engine, i.e. the corresponding GSP message
+interface and provide an API for chid allocation and channel handling.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+GR engine
+---------
+
+Implement support for the graphics engine, i.e. the corresponding GSP message
+interface and provide an API for (golden) context creation and promotion.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+CE engine
+---------
+
+Implement support for the copy engine, i.e. the corresponding GSP message
+interface.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+VFN IRQ controller
+------------------
+
+Support for the VFN interrupt controller.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+External APIs
+=============
+
+nova-core base API
+------------------
+
+Work out the common pieces of the API to connect 2nd level drivers, i.e. vGPU
+manager and nova-drm.
+
+| Complexity: Advanced
+
+vGPU manager API
+----------------
+
+Work out the API parts required by the vGPU manager, which are not covered by
+the base API.
+
+| Complexity: Advanced
+
+nova-core C API
+---------------
+
+Implement a C wrapper for the APIs required by the vGPU manager driver.
+
+| Complexity: Intermediate
+
+Testing
+=======
+
+CI pipeline
+-----------
+
+Investigate option for continuous integration testing.
+
+This can go from as simple as running KUnit tests over running (graphics) CTS to
+booting up (multiple) guest VMs to test VFIO use-cases.
+
+It might also be worth to consider the introduction of a new test suite directly
+sitting on top of the uAPI for more targeted testing and debugging. There may be
+options for collaboration / shared code with the Mesa project.
+
+| Complexity: Advanced
Documentation/gpu/nova/guidelines.rst new file +69 -0
new file mode 100644
index 000000000000..13ab13984a18
@@ -0,0 +1,69 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+==========
+Guidelines
+==========
+
+This document describes the general project guidelines that apply to nova-core
+and nova-drm.
+
+Language
+========
+
+The Nova project uses the Rust programming language. In this context, all rules
+of the Rust for Linux project as documented in
+:doc:`../../rust/general-information` apply. Additionally, the following rules
+apply.
+
+- Unless technically necessary otherwise (e.g. uAPI), any driver code is written
+  in Rust.
+
+- Unless technically necessary, unsafe Rust code must be avoided. In case of
+  technical necessity, unsafe code should be isolated in a separate component
+  providing a safe API for other driver code to use.
+
+Style
+-----
+
+All rules of the Rust for Linux project as documented in
+:doc:`../../rust/coding-guidelines` apply.
+
+For a submit checklist, please also see the `Rust for Linux Submit checklist
+addendum <https://rust-for-linux.com/contributing#submit-checklist-addendum>`_.
+
+Documentation
+=============
+
+The availability of proper documentation is essential in terms of scalability,
+accessibility for new contributors and maintainability of a project in general,
+but especially for a driver running as complex hardware as Nova is targeting.
+
+Hence, adding documentation of any kind is very much encouraged by the project.
+
+Besides that, there are some minimum requirements.
+
+- Every non-private structure needs at least a brief doc comment explaining the
+  semantical sense of the structure, as well as potential locking and lifetime
+  requirements. It is encouraged to have the same minimum documentation for
+  non-trivial private structures.
+
+- uAPIs must be fully documented with kernel-doc comments; additionally, the
+  semantical behavior must be explained including potential special or corner
+  cases.
+
+- The APIs connecting the 1st level driver (nova-core) with 2nd level drivers
+  must be fully documented. This includes doc comments, potential locking and
+  lifetime requirements, as well as example code if applicable.
+
+- Abbreviations must be explained when introduced; terminology must be uniquely
+  defined.
+
+- Register addresses, layouts, shift values and masks must be defined properly;
+  unless obvious, the semantical sense must be documented. This only applies if
+  the author is able to obtain the corresponding information.
+
+Acceptance Criteria
+===================
+
+- Patches must only be applied if reviewed by at least one other person on the
+  mailing list; this also applies for maintainers.
Documentation/gpu/nova/index.rst new file +30 -0
new file mode 100644
index 000000000000..2701b3f4af35
@@ -0,0 +1,30 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+=======================
+nova NVIDIA GPU drivers
+=======================
+
+The nova driver project consists out of two separate drivers nova-core and
+nova-drm and intends to supersede the nouveau driver for NVIDIA GPUs based on
+the GPU System Processor (GSP).
+
+The following documents apply to both nova-core and nova-drm.
+
+.. toctree::
+   :titlesonly:
+
+   guidelines
+
+nova-core
+=========
+
+The nova-core driver is the core driver for NVIDIA GPUs based on GSP. nova-core,
+as the 1st level driver, provides an abstraction around the GPUs hard- and
+firmware interfaces providing a common base for 2nd level drivers, such as the
+vGPU manager VFIO driver and the nova-drm driver.
+
+.. toctree::
+   :titlesonly:
+
+   core/guidelines
+   core/todo
MAINTAINERS +1 -1
index 5d5b7ed7da9e..ed618e8757a5 100644
@@ -7454,6 +7454,7 @@ Q:	https://patchwork.freedesktop.org/project/nouveau/
 B:	https://gitlab.freedesktop.org/drm/nova/-/issues
 C:	irc://irc.oftc.net/nouveau
 T:	git https://gitlab.freedesktop.org/drm/nova.git nova-next
+F:	Documentation/gpu/nova/
 F:	drivers/gpu/nova-core/
 
 DRM DRIVER FOR OLIMEX LCD-OLINUXINO PANELS
--

2.48.1

#5 lore raw

Re: [PATCH v3 2/2] gpu: nova-core: add initial documentation

In reply to Danilo Krummrich
Quoted 341 lines · Danilo Krummrich

Add the initial documentation of the Nova project.

The initial project documentation consists out of a brief introduction of the project, as well as project guidelines both general and nova-core specific and a task list for nova-core specifically.

The task list is divided into tasks for general Rust infrastructure required by the project, tasks regarding GSP enablement and firmware abstraction, general GPU driver tasks as well as tasks related to external API design and test infrastructure.

---
Changes in v3:
- Replace some Rust specific rules with links to existing R4L documentation.
- Link in R4L submit checklist.
- Update task entry "Page abstraction for foreign pages" with Lina's work.

Changes in v2:
- Add task "Generic register abstraction".
- Change complexity of "Debugfs abstractions".

---
 Documentation/gpu/drivers.rst              |   1 +
 Documentation/gpu/nova/core/guidelines.rst |  24 ++
 Documentation/gpu/nova/core/todo.rst       | 446 +++++++++++++++++++++
 Documentation/gpu/nova/guidelines.rst      |  69 ++++
 Documentation/gpu/nova/index.rst           |  30 ++
 MAINTAINERS                                |   1 +
 6 files changed, 571 insertions(+)
 create mode 100644 Documentation/gpu/nova/core/guidelines.rst
 create mode 100644 Documentation/gpu/nova/core/todo.rst
 create mode 100644 Documentation/gpu/nova/guidelines.rst
 create mode 100644 Documentation/gpu/nova/index.rst
Documentation/gpu/drivers.rst +1 -0
index 1f17ad0790d7..7c2c5dcb5fd4 100644
@@ -24,6 +24,7 @@ GPU Driver Documentation
    panfrost
    panthor
    zynqmp
+   nova/index
 
 .. only::  subproject and html
 
Documentation/gpu/nova/core/guidelines.rst new file +24 -0
new file mode 100644
index 000000000000..a389d65d7982
@@ -0,0 +1,24 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+==========
+Guidelines
+==========
+
+This documents contains the guidelines for nova-core. Additionally, all common
+guidelines of the Nova project do apply.
+
+Driver API
+==========
+
+One main purpose of nova-core is to implement the abstraction around the
+firmware interface of GSP and provide a firmware (version) independent API for
+2nd level drivers, such as nova-drm or the vGPU manager VFIO driver.
+
+Therefore, it is not permitted to leak firmware (version) specifics, through the
+driver API, to 2nd level drivers.
+
+Acceptance Criteria
+===================
+
+- To the extend possible, patches submitted to nova-core must be tested for
+  regressions with all 2nd level drivers.
Documentation/gpu/nova/core/todo.rst new file +259 -0
new file mode 100644
index 000000000000..3e8d2125da9d
@@ -0,0 +1,446 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+=========
+Task List
+=========
+
+Tasks may have the following fields:
+
+- ``Complexity``: Describes the required familiarity with Rust and / or the
+  corresponding kernel APIs or subsystems. There are four different complexities,
+  ``Beginner``, ``Intermediate``, ``Advanced`` and ``Expert``.
+- ``Reference``: References to other tasks.
+- ``Link``: Links to external resources.
+- ``Contact``: The person that can be contacted for further information about
+  the task.
+
+Enablement (Rust)
+=================
+
+Tasks that are not directly related to nova-core, but are preconditions in terms
+of required APIs.
+
+FromPrimitive API
+-----------------
+
+Sometimes the need arises to convert a number to a value of an enum or a
+structure.
+
+A good example from nova-core would be the ``Chipset`` enum type, which defines
+the value ``AD102``. When probing the GPU the value ``0x192`` can be read from a
+certain register indication the chipset AD102. Hence, the enum value ``AD102``
+should be derived from the number ``0x192``. Currently, nova-core uses a custom
+implementation (``Chipset::from_u32`` for this.
+
+Instead, it would be desirable to have something like the ``FromPrimitive``
+trait [1] from the num crate.
+
+Having this generalization also helps with implementing a generic macro that
+automatically generates the corresponding mappings between a value and a number.
+
+| Complexity: Beginner
+| Link: https://docs.rs/num/latest/num/trait.FromPrimitive.html
+
+Generic register abstraction
+----------------------------
+
+Work out how register constants and structures can be automatically generated
+through generalized macros.
+
+Example:
+
+.. code-block:: rust
+
+	register!(BOOT0, 0x0, u32, pci::Bar<SIZE>, Fields [
+	   MINOR_REVISION(3:0, RO),
+	   MAJOR_REVISION(7:4, RO),
+	   REVISION(7:0, RO), // Virtual register combining major and minor rev.
+	])
+
+This could expand to something like:
+
+.. code-block:: rust
+
+	const BOOT0_OFFSET: usize = 0x00000000;
+	const BOOT0_MINOR_REVISION_SHIFT: u8 = 0;
+	const BOOT0_MINOR_REVISION_MASK: u32 = 0x0000000f;
+	const BOOT0_MAJOR_REVISION_SHIFT: u8 = 4;
+	const BOOT0_MAJOR_REVISION_MASK: u32 = 0x000000f0;
+	const BOOT0_REVISION_SHIFT: u8 = BOOT0_MINOR_REVISION_SHIFT;
+	const BOOT0_REVISION_MASK: u32 = BOOT0_MINOR_REVISION_MASK | BOOT0_MAJOR_REVISION_MASK;
+
+	struct Boot0(u32);
+
+	impl Boot0 {
+	   #[inline]
+	   fn read(bar: &RevocableGuard<'_, pci::Bar<SIZE>>) -> Self {
+	      Self(bar.readl(BOOT0_OFFSET))
+	   }
+
+	   #[inline]
+	   fn minor_revision(&self) -> u32 {
+	      (self.0 & BOOT0_MINOR_REVISION_MASK) >> BOOT0_MINOR_REVISION_SHIFT
+	   }
+
+	   #[inline]
+	   fn major_revision(&self) -> u32 {
+	      (self.0 & BOOT0_MAJOR_REVISION_MASK) >> BOOT0_MAJOR_REVISION_SHIFT
+	   }
+
+	   #[inline]
+	   fn revision(&self) -> u32 {
+	      (self.0 & BOOT0_REVISION_MASK) >> BOOT0_REVISION_SHIFT
+	   }
+	}
+
+Usage:
+
+.. code-block:: rust
+
+	let bar = bar.try_access().ok_or(ENXIO)?;
+
+	let boot0 = Boot0::read(&bar);
+	pr_info!("Revision: {}\n", boot0.revision());
+
+| Complexity: Advanced
+
+Delay / Sleep abstractions
+--------------------------
+
+Rust abstractions for the kernel's delay() and sleep() functions.
+
+There is some ongoing work from FUJITA Tomonori [1], which has not seen any updates
+since Oct. 24.
+
+| Complexity: Beginner
+| Link: https://lore.kernel.org/netdev/[email protected]/ [1]
+
+IRQ abstractions
+----------------
+
+Rust abstractions for IRQ handling.
+
+There is active ongoing work from Daniel Almeida [1] for the "core" abstractions
+to request IRQs.
+
+Besides optional review and testing work, the required ``pci::Device`` code
+around those core abstractions needs to be worked out.
+
+| Complexity: Intermediate
+| Link: https://lore.kernel.org/lkml/[email protected]/ [1]
+| Contact: Daniel Almeida
+
+Page abstraction for foreign pages
+----------------------------------
+
+Rust abstractions for pages not created by the Rust page abstraction without
+direct ownership.
+
+There is active onging work from Abdiel Janulgue [1] and Lina [2].
+
+| Complexity: Advanced
+| Link: https://lore.kernel.org/linux-mm/[email protected]/ [1]
+| Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [2]
+
+Scatterlist / sg_table abstractions
+-----------------------------------
+
+Rust abstractions for scatterlist / sg_table.
+
+There is preceding work from Abdiel Janulgue, which hasn't made it to the
+mailing list yet.
+
+| Complexity: Intermediate
+| Contact: Abdiel Janulgue
+
+ELF utils
+---------
+
+Rust implementation of ELF header representation to retrieve section header
+tables, names, and data from an ELF-formatted images.
+
+There is preceding work from Abdiel Janulgue, which hasn't made it to the
+mailing list yet.
+
+| Complexity: Beginner
+| Contact: Abdiel Janulgue
+
+PCI MISC APIs
+-------------
+
+Extend the existing PCI device / driver abstractions by SR-IOV, config space,
+capability, MSI API abstractions.
+
+| Complexity: Beginner
+
+Auxiliary bus abstractions
+--------------------------
+
+Rust abstraction for the auxiliary bus APIs.
+
+This is needed to connect nova-core to the nova-drm driver.
+
+| Complexity: Intermediate
+
+Debugfs abstractions
+--------------------
+
+Rust abstraction for debugfs APIs.
+
+| Reference: Export GSP log buffers
+| Complexity: Intermediate
+
+Vec extensions
+--------------
+
+Implement ``Vec::truncate`` and ``Vec::resize``.
+
+Currently this is used for some experimental code to parse the vBIOS.
+
+| Reference vBIOS support
+| Complexity: Beginner
+
+GPU (general)
+=============
+
+Parse firmware headers
+----------------------
+
+Parse ELF headers from the firmware files loaded from the filesystem.
+
+| Reference: ELF utils
+| Complexity: Beginner
+| Contact: Abdiel Janulgue
+
+Build radix3 page table
+-----------------------
+
+Build the radix3 page table to map the firmware.
+
+| Complexity: Intermediate
+| Contact: Abdiel Janulgue
+
+vBIOS support
+-------------
+
+Parse the vBIOS and probe the structures required for driver initialization.
+
+| Contact: Dave Airlie
+| Reference: Vec extensions
+| Complexity: Intermediate
+
+Initial Devinit support
+-----------------------
+
+Implement BIOS Device Initialization, i.e. memory sizing, waiting, PLL
+configuration.
+
+| Contact: Dave Airlie
+| Complexity: Beginner
+
+Boot Falcon controller
+----------------------
+
+Infrastructure to load and execute falcon (sec2) firmware images; handle the
+GSP falcon processor and fwsec loading.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+GPU Timer support
+-----------------
+
+Support for the GPU's internal timer peripheral.
+
+| Complexity: Beginner
+| Contact: Dave Airlie
+
+MMU / PT management
+-------------------

Documentation/gpu/nova/core/todo.rst line 269

Quoted 10 lines
Documentation/gpu/nova/core/todo.rst new file +10 -0
+
+Work out the architecture for MMU / page table management.
+
+We need to consider that nova-drm will need rather fine-grained control,
+especially in terms of locking, in order to be able to implement asynchronous
+Vulkan queues.
+
+While generally sharing the corresponding code is desirable, it needs to be
+evaluated how (and if at all) sharing the corresponding code is expedient.
+

Looking purely from curiosity PoV...

Any plans to wrap things like GPU VM in rust?

Documentation/gpu/nova/core/todo.rst line 282

Quoted 13 lines
Documentation/gpu/nova/core/todo.rst new file +13 -0
+| Complexity: Expert
+
+VRAM memory allocator
+---------------------
+
+Investigate options for a VRAM memory allocator.
+
+Some possible options:
+  - Rust abstractions for
+    - RB tree (interval tree) / drm_mm
+    - maple_tree
+  - native Rust collections
+

Here what about using TTM or DRM buddy?

Matt

Quoted 290 lines
Documentation/gpu/nova/core/todo.rst new file +164 -0
+| Complexity: Advanced
+
+Instance Memory
+---------------
+
+Implement support for instmem (bar2) used to store page tables.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+GPU System Processor (GSP)
+==========================
+
+Export GSP log buffers
+----------------------
+
+Recent patches from Timur Tabi [1] added support to expose GSP-RM log buffers
+(even after failure to probe the driver) through debugfs.
+
+This is also an interesting feature for nova-core, especially in the early days.
+
+| Link: https://lore.kernel.org/nouveau/[email protected]/ [1]
+| Reference: Debugfs abstractions
+| Complexity: Intermediate
+
+GSP firmware abstraction
+------------------------
+
+The GSP-RM firmware API is unstable and may incompatibly change from version to
+version, in terms of data structures and semantics.
+
+This problem is one of the big motivations for using Rust for nova-core, since
+it turns out that Rust's procedural macro feature provides a rather elegant way
+to address this issue:
+
+1. generate Rust structures from the C headers in a separate namespace per version
+2. build abstraction structures (within a generic namespace) that implement the
+   firmware interfaces; annotate the differences in implementation with version
+   identifiers
+3. use a procedural macro to generate the actual per version implementation out
+   of this abstraction
+4. instantiate the correct version type one on runtime (can be sure that all
+   have the same interface because it's defined by a common trait)
+
+There is a PoC implementation of this pattern, in the context of the nova-core
+PoC driver.
+
+This task aims at refining the feature and ideally generalize it, to be usable
+by other drivers as well.
+
+| Complexity: Expert
+
+GSP message queue
+-----------------
+
+Implement low level GSP message queue (command, status) for communication
+between the kernel driver and GSP.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+Bootstrap GSP
+-------------
+
+Call the boot firmware to boot the GSP processor; execute initial control
+messages.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+Client / Device APIs
+--------------------
+
+Implement the GSP message interface for client / device allocation and the
+corresponding client and device allocation APIs.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+Bar PDE handling
+----------------
+
+Synchronize page table handling for BARs between the kernel driver and GSP.
+
+| Complexity: Beginner
+| Contact: Dave Airlie
+
+FIFO engine
+-----------
+
+Implement support for the FIFO engine, i.e. the corresponding GSP message
+interface and provide an API for chid allocation and channel handling.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+GR engine
+---------
+
+Implement support for the graphics engine, i.e. the corresponding GSP message
+interface and provide an API for (golden) context creation and promotion.
+
+| Complexity: Advanced
+| Contact: Dave Airlie
+
+CE engine
+---------
+
+Implement support for the copy engine, i.e. the corresponding GSP message
+interface.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+VFN IRQ controller
+------------------
+
+Support for the VFN interrupt controller.
+
+| Complexity: Intermediate
+| Contact: Dave Airlie
+
+External APIs
+=============
+
+nova-core base API
+------------------
+
+Work out the common pieces of the API to connect 2nd level drivers, i.e. vGPU
+manager and nova-drm.
+
+| Complexity: Advanced
+
+vGPU manager API
+----------------
+
+Work out the API parts required by the vGPU manager, which are not covered by
+the base API.
+
+| Complexity: Advanced
+
+nova-core C API
+---------------
+
+Implement a C wrapper for the APIs required by the vGPU manager driver.
+
+| Complexity: Intermediate
+
+Testing
+=======
+
+CI pipeline
+-----------
+
+Investigate option for continuous integration testing.
+
+This can go from as simple as running KUnit tests over running (graphics) CTS to
+booting up (multiple) guest VMs to test VFIO use-cases.
+
+It might also be worth to consider the introduction of a new test suite directly
+sitting on top of the uAPI for more targeted testing and debugging. There may be
+options for collaboration / shared code with the Mesa project.
+
+| Complexity: Advanced
Documentation/gpu/nova/guidelines.rst new file +69 -0
new file mode 100644
index 000000000000..13ab13984a18
@@ -0,0 +1,69 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+==========
+Guidelines
+==========
+
+This document describes the general project guidelines that apply to nova-core
+and nova-drm.
+
+Language
+========
+
+The Nova project uses the Rust programming language. In this context, all rules
+of the Rust for Linux project as documented in
+:doc:`../../rust/general-information` apply. Additionally, the following rules
+apply.
+
+- Unless technically necessary otherwise (e.g. uAPI), any driver code is written
+  in Rust.
+
+- Unless technically necessary, unsafe Rust code must be avoided. In case of
+  technical necessity, unsafe code should be isolated in a separate component
+  providing a safe API for other driver code to use.
+
+Style
+-----
+
+All rules of the Rust for Linux project as documented in
+:doc:`../../rust/coding-guidelines` apply.
+
+For a submit checklist, please also see the `Rust for Linux Submit checklist
+addendum <https://rust-for-linux.com/contributing#submit-checklist-addendum>`_.
+
+Documentation
+=============
+
+The availability of proper documentation is essential in terms of scalability,
+accessibility for new contributors and maintainability of a project in general,
+but especially for a driver running as complex hardware as Nova is targeting.
+
+Hence, adding documentation of any kind is very much encouraged by the project.
+
+Besides that, there are some minimum requirements.
+
+- Every non-private structure needs at least a brief doc comment explaining the
+  semantical sense of the structure, as well as potential locking and lifetime
+  requirements. It is encouraged to have the same minimum documentation for
+  non-trivial private structures.
+
+- uAPIs must be fully documented with kernel-doc comments; additionally, the
+  semantical behavior must be explained including potential special or corner
+  cases.
+
+- The APIs connecting the 1st level driver (nova-core) with 2nd level drivers
+  must be fully documented. This includes doc comments, potential locking and
+  lifetime requirements, as well as example code if applicable.
+
+- Abbreviations must be explained when introduced; terminology must be uniquely
+  defined.
+
+- Register addresses, layouts, shift values and masks must be defined properly;
+  unless obvious, the semantical sense must be documented. This only applies if
+  the author is able to obtain the corresponding information.
+
+Acceptance Criteria
+===================
+
+- Patches must only be applied if reviewed by at least one other person on the
+  mailing list; this also applies for maintainers.
Documentation/gpu/nova/index.rst new file +30 -0
new file mode 100644
index 000000000000..2701b3f4af35
@@ -0,0 +1,30 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+=======================
+nova NVIDIA GPU drivers
+=======================
+
+The nova driver project consists out of two separate drivers nova-core and
+nova-drm and intends to supersede the nouveau driver for NVIDIA GPUs based on
+the GPU System Processor (GSP).
+
+The following documents apply to both nova-core and nova-drm.
+
+.. toctree::
+   :titlesonly:
+
+   guidelines
+
+nova-core
+=========
+
+The nova-core driver is the core driver for NVIDIA GPUs based on GSP. nova-core,
+as the 1st level driver, provides an abstraction around the GPUs hard- and
+firmware interfaces providing a common base for 2nd level drivers, such as the
+vGPU manager VFIO driver and the nova-drm driver.
+
+.. toctree::
+   :titlesonly:
+
+   core/guidelines
+   core/todo
MAINTAINERS +1 -0
index 5d5b7ed7da9e..ed618e8757a5 100644
@@ -7454,6 +7454,7 @@ Q:	https://patchwork.freedesktop.org/project/nouveau/
 B:	https://gitlab.freedesktop.org/drm/nova/-/issues
 C:	irc://irc.oftc.net/nouveau
 T:	git https://gitlab.freedesktop.org/drm/nova.git nova-next
+F:	Documentation/gpu/nova/
 F:	drivers/gpu/nova-core/
 
 DRM DRIVER FOR OLIMEX LCD-OLINUXINO PANELS
Signature · 1 line
2.48.1
#6 lore raw
In reply to Danilo Krummrich

drivers/gpu/nova-core/Kconfig line 6

Quoted 6 lines · Danilo Krummrich
drivers/gpu/nova-core/Kconfig new file +6 -0
+config NOVA_CORE
+	tristate "Nova Core GPU driver"
+	depends on PCI
+	depends on RUST
+	depends on RUST_FW_LOADER_ABSTRACTIONS
+	default n

Tiny nit, if you happen to respin this, "default n" is always the default, so there's never a need to specify it.

drivers/gpu/nova-core/gpu.rs line 152

Quoted 7 lines
drivers/gpu/nova-core/gpu.rs new file +7 -0
+impl Firmware {
+    fn new(dev: &device::Device, spec: &Spec, ver: &str) -> Result<Firmware> {
+        let mut chip_name = CString::try_from_fmt(fmt!("{}", spec.chipset))?;
+        chip_name.make_ascii_lowercase();
+
+        let request = |name_| {
+            CString::try_from_fmt(fmt!("nvidia/{}/gsp/{}-{}.bin", &*chip_name, name_, ver))

How does this match up with the MODULE_FIRMWARE() aliases that end up in a kernel module so that the tools know to add the firmware to the system in the proper place (i.e. initramfs or something like that)?

I always thought you needed to individually list the firmware files, or does the rust implementation now somehow handle that in a programatic way from strings like this?

thanks,

greg k-h

author maintainer
#7 lore raw
Quoted 10 lines · Greg KH

drivers/gpu/nova-core/Kconfig line 6

Quoted 6 lines · Danilo Krummrich
drivers/gpu/nova-core/Kconfig new file +6 -0
+config NOVA_CORE
+	tristate "Nova Core GPU driver"
+	depends on PCI
+	depends on RUST
+	depends on RUST_FW_LOADER_ABSTRACTIONS
+	default n

Tiny nit, if you happen to respin this, "default n" is always the default, so there's never a need to specify it.

At some point we'll want to change that to 'default m', and I thought keeping it explicit is probably a good reminder. But I'm also fine removing it.

Quoted 13 lines

drivers/gpu/nova-core/gpu.rs line 152

Quoted 8 lines
drivers/gpu/nova-core/gpu.rs new file +7 -0
+impl Firmware {
+    fn new(dev: &device::Device, spec: &Spec, ver: &str) -> Result<Firmware> {
+        let mut chip_name = CString::try_from_fmt(fmt!("{}", spec.chipset))?;
+        chip_name.make_ascii_lowercase();
+
+        let request = |name_| {
+            CString::try_from_fmt(fmt!("nvidia/{}/gsp/{}-{}.bin", &*chip_name, name_, ver))

How does this match up with the MODULE_FIRMWARE() aliases that end up in a kernel module so that the tools know to add the firmware to the system in the proper place (i.e. initramfs or something like that)?

Quoted 3 lines

I always thought you needed to individually list the firmware files, or does the rust implementation now somehow handle that in a programatic way from strings like this?

That'd be nice, but the firmware we load is (or in general might be) only a subset of the firmware that the module needs potentially.

So, you're right, all (potentially) required firmware files need to be listed in the module!() macro's firmware field (or in this case within module_pci_driver!()).

Back when I wrote this code we haven't had this field yet -- thanks for reminding me of that.

#8 lore raw
In reply to Danilo Krummrich
Quoted 423 lines · Danilo Krummrich

Add the initial nova-core driver stub.

nova-core is intended to serve as a common base for nova-drm (the corresponding DRM driver) and the vGPU manager VFIO driver, serving as a hard- and firmware abstraction layer for GSP-based NVIDIA GPUs.

The Nova project, including nova-core and nova-drm, in the long term, is intended to serve as the successor of Nouveau for all GSP-based GPUs.

The motivation for both, starting a successor project for Nouveau and doing so using the Rust programming language, is documented in detail through a previous post on the mailing list [1], an LWN article [2] and a talk from LPC '24.

In order to avoid the chicken and egg problem to require a user to upstream Rust abstractions, but at the same time require the Rust abstractions to implement the driver, nova-core kicks off as a driver stub and is subsequently developed upstream.

---
Changes in v3:
- impl TryFrom<u32> for Chipset
- add Chipset::arch()
- initialize revision from Boot0
- in Firmware, eliminate repeating code pattern using a closure (thanks to Alexandre)
- use #[expect(dead_code)] for Firmware

Changes in v2:
- Fix module name in Kconfig description. (John)
- Expand Kconfig description a bit. (John)
- Expand name for PCI BAR0 region.
- Do not store / print boot0 raw register value. (John)
- Rename CardType to Architecture, rename enum names to represent the architecture name and adjust enum values according to the register definition. (John)
- Add an abstraction for register accesses.
- Print chipset, architecture and revision.
- Load bootloader firmware. (Timur)

---
 MAINTAINERS                        |  10 ++
 drivers/gpu/Makefile               |   1 +
 drivers/gpu/nova-core/Kconfig      |  14 +++
 drivers/gpu/nova-core/Makefile     |   3 +
 drivers/gpu/nova-core/driver.rs    |  47 +++++++
 drivers/gpu/nova-core/gpu.rs       | 189 +++++++++++++++++++++++++++++
 drivers/gpu/nova-core/nova_core.rs |  15 +++
 drivers/gpu/nova-core/regs.rs      |  56 +++++++++
 drivers/video/Kconfig              |   1 +
 9 files changed, 336 insertions(+)
 create mode 100644 drivers/gpu/nova-core/Kconfig
 create mode 100644 drivers/gpu/nova-core/Makefile
 create mode 100644 drivers/gpu/nova-core/driver.rs
 create mode 100644 drivers/gpu/nova-core/gpu.rs
 create mode 100644 drivers/gpu/nova-core/nova_core.rs
 create mode 100644 drivers/gpu/nova-core/regs.rs
MAINTAINERS +10 -0
index 25c86f47353d..5d5b7ed7da9e 100644
@@ -7446,6 +7446,16 @@ T:	git https://gitlab.freedesktop.org/drm/nouveau.git
 F:	drivers/gpu/drm/nouveau/
 F:	include/uapi/drm/nouveau_drm.h
 
+CORE DRIVER FOR NVIDIA GPUS [RUST]
+M:	Danilo Krummrich <[email protected]>
+L:	[email protected]
+S:	Supported
+Q:	https://patchwork.freedesktop.org/project/nouveau/
+B:	https://gitlab.freedesktop.org/drm/nova/-/issues
+C:	irc://irc.oftc.net/nouveau
+T:	git https://gitlab.freedesktop.org/drm/nova.git nova-next
+F:	drivers/gpu/nova-core/
+
 DRM DRIVER FOR OLIMEX LCD-OLINUXINO PANELS
 M:	Stefan Mavrodiev <[email protected]>
 S:	Maintained
drivers/gpu/Makefile +1 -0
index 8997f0096545..36a54d456630 100644
@@ -5,3 +5,4 @@
 obj-y			+= host1x/ drm/ vga/
 obj-$(CONFIG_IMX_IPUV3_CORE)	+= ipu-v3/
 obj-$(CONFIG_TRACE_GPU_MEM)		+= trace/
+obj-$(CONFIG_NOVA_CORE)		+= nova-core/
drivers/gpu/nova-core/Kconfig new file +14 -0
new file mode 100644
index 000000000000..ad0c06756516
@@ -0,0 +1,14 @@
+config NOVA_CORE
+	tristate "Nova Core GPU driver"
+	depends on PCI
+	depends on RUST
+	depends on RUST_FW_LOADER_ABSTRACTIONS
+	default n
+	help
+	  Choose this if you want to build the Nova Core driver for Nvidia
+	  GPUs based on the GPU System Processor (GSP). This is true for Turing
+	  and later GPUs.
+
+	  This driver is work in progress and may not be functional.
+
+	  If M is selected, the module will be called nova_core.
drivers/gpu/nova-core/Makefile new file +3 -0
new file mode 100644
index 000000000000..2d78c50126e1
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_NOVA_CORE) += nova_core.o
drivers/gpu/nova-core/driver.rs new file +47 -0
new file mode 100644
index 000000000000..63c19f140fbd
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use kernel::{bindings, c_str, pci, prelude::*};
+
+use crate::gpu::Gpu;
+
+#[pin_data]
+pub(crate) struct NovaCore {
+    #[pin]
+    pub(crate) gpu: Gpu,
+}
+
+const BAR0_SIZE: usize = 8;
+pub(crate) type Bar0 = pci::Bar<BAR0_SIZE>;
+
+kernel::pci_device_table!(
+    PCI_TABLE,
+    MODULE_PCI_TABLE,
+    <NovaCore as pci::Driver>::IdInfo,
+    [(
+        pci::DeviceId::from_id(bindings::PCI_VENDOR_ID_NVIDIA, bindings::PCI_ANY_ID as _),
+        ()
+    )]
+);
+
+impl pci::Driver for NovaCore {
+    type IdInfo = ();
+    const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
+
+    fn probe(pdev: &mut pci::Device, _info: &Self::IdInfo) -> Result<Pin<KBox<Self>>> {
+        dev_dbg!(pdev.as_ref(), "Probe Nova Core GPU driver.\n");
+
+        pdev.enable_device_mem()?;
+        pdev.set_master();
+
+        let bar = pdev.iomap_region_sized::<BAR0_SIZE>(0, c_str!("nova-core/bar0"))?;
+
+        let this = KBox::pin_init(
+            try_pin_init!(Self {
+                gpu <- Gpu::new(pdev, bar)?,
+            }),
+            GFP_KERNEL,
+        )?;
+
+        Ok(this)
+    }
+}
drivers/gpu/nova-core/gpu.rs new file +189 -0
new file mode 100644
index 000000000000..e7da6a2fa29d
@@ -0,0 +1,189 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use kernel::{
+    device, devres::Devres, error::code::*, firmware, fmt, pci, prelude::*, str::CString,
+};
+
+use crate::driver::Bar0;
+use crate::regs;
+use core::fmt;
+
+/// Enum representation of the GPU chipset.
+#[derive(fmt::Debug)]
+pub(crate) enum Chipset {
+    // Turing
+    TU102 = 0x162,
+    TU104 = 0x164,
+    TU106 = 0x166,
+    TU117 = 0x167,
+    TU116 = 0x168,
+    // Ampere
+    GA102 = 0x172,
+    GA103 = 0x173,
+    GA104 = 0x174,
+    GA106 = 0x176,
+    GA107 = 0x177,
+    // Ada
+    AD102 = 0x192,
+    AD103 = 0x193,
+    AD104 = 0x194,
+    AD106 = 0x196,
+    AD107 = 0x197,
+}
+
+impl Chipset {
+    pub(crate) fn arch(&self) -> Architecture {
+        match self {
+            Self::TU102 | Self::TU104 | Self::TU106 | Self::TU117 | Self::TU116 => {
+                Architecture::Turing
+            }
+            Self::GA102 | Self::GA103 | Self::GA104 | Self::GA106 | Self::GA107 => {
+                Architecture::Ampere
+            }
+            Self::AD102 | Self::AD103 | Self::AD104 | Self::AD106 | Self::AD107 => {
+                Architecture::Ada
+            }
+        }
+    }
+}
+
+// TODO
+//
+// The resulting strings are used to generate firmware paths, hence the
+// generated strings have to be stable.
+//
+// Hence, replace with something like strum_macros derive(Display).
+//
+// For now, redirect to fmt::Debug for convenience.
+impl fmt::Display for Chipset {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}", self)
+    }
+}
+
+// TODO replace with something like derive(FromPrimitive)
+impl TryFrom<u32> for Chipset {
+    type Error = kernel::error::Error;
+
+    fn try_from(value: u32) -> Result<Self, Self::Error> {
+        match value {
+            0x162 => Ok(Chipset::TU102),
+            0x164 => Ok(Chipset::TU104),
+            0x166 => Ok(Chipset::TU106),
+            0x167 => Ok(Chipset::TU117),
+            0x168 => Ok(Chipset::TU116),
+            0x172 => Ok(Chipset::GA102),
+            0x173 => Ok(Chipset::GA103),
+            0x174 => Ok(Chipset::GA104),
+            0x176 => Ok(Chipset::GA106),
+            0x177 => Ok(Chipset::GA107),
+            0x192 => Ok(Chipset::AD102),
+            0x193 => Ok(Chipset::AD103),
+            0x194 => Ok(Chipset::AD104),
+            0x196 => Ok(Chipset::AD106),
+            0x197 => Ok(Chipset::AD107),
+            _ => Err(ENODEV),
+        }
+    }
+}
+
+/// Enum representation of the GPU generation.
+#[derive(fmt::Debug)]
+pub(crate) enum Architecture {
+    Turing,
+    Ampere,
+    Ada,
+}
+
+pub(crate) struct Revision {
+    major: u8,
+    minor: u8,
+}
+
+impl Revision {
+    fn from_boot0(boot0: regs::Boot0) -> Self {
+        Self {
+            major: boot0.major_rev(),
+            minor: boot0.minor_rev(),
+        }
+    }
+}
+
+impl fmt::Display for Revision {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:x}.{:x}", self.major, self.minor)
+    }
+}
+
+/// Structure holding the metadata of the GPU.
+pub(crate) struct Spec {
+    chipset: Chipset,
+    /// The revision of the chipset.
+    revision: Revision,
+}
+
+impl Spec {
+    fn new(bar: &Devres<Bar0>) -> Result<Spec> {
+        let bar = bar.try_access().ok_or(ENXIO)?;
+        let boot0 = regs::Boot0::read(&bar);
+
+        Ok(Self {
+            chipset: boot0.chipset().try_into()?,
+            revision: Revision::from_boot0(boot0),
+        })
+    }
+}
+
+/// Structure encapsulating the firmware blobs required for the GPU to operate.
+#[expect(dead_code)]
+pub(crate) struct Firmware {
+    booter_load: firmware::Firmware,
+    booter_unload: firmware::Firmware,
+    bootloader: firmware::Firmware,
+    gsp: firmware::Firmware,
+}
+
+impl Firmware {
+    fn new(dev: &device::Device, spec: &Spec, ver: &str) -> Result<Firmware> {
+        let mut chip_name = CString::try_from_fmt(fmt!("{}", spec.chipset))?;
+        chip_name.make_ascii_lowercase();
+
+        let request = |name_| {
+            CString::try_from_fmt(fmt!("nvidia/{}/gsp/{}-{}.bin", &*chip_name, name_, ver))
+                .and_then(|path| firmware::Firmware::request(&path, dev))
+        };
+
+        Ok(Firmware {
+            booter_load: request("booter_load")?,
+            booter_unload: request("booter_unload")?,
+            bootloader: request("bootloader")?,
+            gsp: request("gsp")?,
+        })
+    }
+}
+
+/// Structure holding the resources required to operate the GPU.
+#[pin_data]
+pub(crate) struct Gpu {
+    spec: Spec,
+    /// MMIO mapping of PCI BAR 0
+    bar: Devres<Bar0>,
+    fw: Firmware,
+}
+
+impl Gpu {
+    pub(crate) fn new(pdev: &pci::Device, bar: Devres<Bar0>) -> Result<impl PinInit<Self>> {
+        let spec = Spec::new(&bar)?;
+        let fw = Firmware::new(pdev.as_ref(), &spec, "535.113.01")?;
+
+        dev_info!(
+            pdev.as_ref(),
+            "NVIDIA (Chipset: {}, Architecture: {:?}, Revision: {})\n",
+            spec.chipset,
+            spec.chipset.arch(),
+            spec.revision
+        );
+
+        Ok(pin_init!(Self { spec, bar, fw }))
+    }
+}
drivers/gpu/nova-core/nova_core.rs new file +15 -0
new file mode 100644
index 000000000000..5d0230042793
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Nova Core GPU Driver
+
+mod driver;
+mod gpu;
+mod regs;
+
+kernel::module_pci_driver! {
+    type: driver::NovaCore,
+    name: "NovaCore",
+    author: "Danilo Krummrich",
+    description: "Nova Core GPU driver",
+    license: "GPL v2",
+}
drivers/gpu/nova-core/regs.rs new file +28 -0
new file mode 100644
index 000000000000..f2766f95e9d1
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use crate::driver::Bar0;
+use kernel::revocable::RevocableGuard;
+
+// TODO
+//
+// Create register definitions via generic macros. See task "Generic register
+// abstraction" in Documentation/gpu/nova/core/todo.rst.
+
+const BOOT0_OFFSET: usize = 0x00000000;
+
+// 3:0 - chipset minor revision
+const BOOT0_MINOR_REV_SHIFT: u8 = 0;
+const BOOT0_MINOR_REV_MASK: u32 = 0x0000000f;
+
+// 7:4 - chipset major revision
+const BOOT0_MAJOR_REV_SHIFT: u8 = 4;
+const BOOT0_MAJOR_REV_MASK: u32 = 0x000000f0;
+
+// 23:20 - chipset implementation Identifier (depends on architecture)
+const BOOT0_IMPL_SHIFT: u8 = 20;
+const BOOT0_IMPL_MASK: u32 = 0x00f00000;
+
+// 28:24 - chipset architecture identifier
+const BOOT0_ARCH_MASK: u32 = 0x1f000000;
+
+// 28:20 - chipset identifier (virtual register field combining BOOT0_IMPL and

drivers/gpu/nova-core/regs.rs line 38

Quoted 10 lines
drivers/gpu/nova-core/regs.rs new file +10 -0
+//         BOOT0_ARCH)
+const BOOT0_CHIPSET_SHIFT: u8 = BOOT0_IMPL_SHIFT;
+const BOOT0_CHIPSET_MASK: u32 = BOOT0_IMPL_MASK | BOOT0_ARCH_MASK;
+
+#[derive(Copy, Clone)]
+pub(crate) struct Boot0(u32);
+
+impl Boot0 {
+    #[inline]
+    pub(crate) fn read(bar: &RevocableGuard<'_, Bar0>) -> Self {

Since RevocableGuard has a Deref implementation you can actually take a &Bar0 here, and let deref coercion do its thing.

Also just for confirmation: is the intent that all register offsets, and masks are kept private within this module, with each register having its own type and dedicated methods to read/write it and extract useful information from it? I haven't really written Rust kernel code before, so I was wondering how we would deal with this problem. This looks like a pretty safe solution.