Commit 3606620b authored by Alexandre Courbot's avatar Alexandre Courbot Committed by Danilo Krummrich
Browse files

gpu: nova-core: update and annotate TODO list 



A few new dependencies are required to remove some of the TODO items:

- A way to safely convert from byte slices to types implementing
  `FromBytes`,
- A way to obtain slices and write into a `CoherentAllocation`,
- Several improvements to the `register!()` macro,
- Alignment operations to powers of two, and an equivalent to the C
  `fls`,
- Support for `xa_alloc` in the XAlloc bindings.

Some items have also become obsolete:

- The auxiliary bus abstractions have been implemented and are in use,
- The ELF utilities are not considered for being part of the core kernel
  bindings anymore.
- VBIOS, falcon and GPU timer have been completed.

We now have quite a few TODO entries in the code, so annotate them with
a 4 letter code representing the corresponding task in `todo.rst`. This
allows to easily find which part of the code corresponds to a given
entry (and conversely).

Signed-off-by: default avatarAlexandre Courbot <acourbot@nvidia.com>
Link: https://lore.kernel.org/r/20250619-nova-frts-v6-24-ecf41ef99252@nvidia.com


Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
parent 859aa3d9

Documentation/gpu/nova/core/todo.rst

+57 −50
Original line number Diff line number Diff line
@@ -14,14 +14,17 @@ Tasks may have the following fields: 
- ``Contact``: The person that can be contacted for further information about

  the task.



A task might have `[ABCD]` code after its name. This code can be used to grep

into the code for `TODO` entries related to it.



Enablement (Rust)

=================



Tasks that are not directly related to nova-core, but are preconditions in terms

of required APIs.



FromPrimitive API

-----------------

FromPrimitive API [FPRI]

------------------------



Sometimes the need arises to convert a number to a value of an enum or a

structure.
@@ -41,8 +44,27 @@ 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

----------------------------

Conversion from byte slices for types implementing FromBytes [TRSM]

-------------------------------------------------------------------



We retrieve several structures from byte streams coming from the BIOS or loaded

firmware. At the moment converting the bytes slice into the proper type require

an inelegant `unsafe` operation; this will go away once `FromBytes` implements

a proper `from_bytes` method.



| Complexity: Beginner



CoherentAllocation improvements [COHA]

--------------------------------------



`CoherentAllocation` needs a safe way to write into the allocation, and to

obtain slices within the allocation.



| Complexity: Beginner

| Contact: Abdiel Janulgue



Generic register abstraction [REGA]

-----------------------------------



Work out how register constants and structures can be automatically generated

through generalized macros.
@@ -102,16 +124,40 @@ Usage: 
	let boot0 = Boot0::read(&bar);

	pr_info!("Revision: {}\n", boot0.revision());



Note: a work-in-progress implementation currently resides in

A work-in-progress implementation currently resides in

`drivers/gpu/nova-core/regs/macros.rs` and is used in nova-core. It would be

nice to improve it (possibly using proc macros) and move it to the `kernel`

crate so it can be used by other components as well.



Features desired before this happens:



* Relative register with build-time base address validation,

* Arrays of registers with build-time index validation,

* Make I/O optional I/O (for field values that are not registers),

* Support other sizes than `u32`,

* Allow visibility control for registers and individual fields,

* Use Rust slice syntax to express fields ranges.



| Complexity: Advanced

| Contact: Alexandre Courbot



Delay / Sleep abstractions

--------------------------

Numerical operations [NUMM]

---------------------------



Nova uses integer operations that are not part of the standard library (or not

implemented in an optimized way for the kernel). These include:



- Aligning up and down to a power of two,

- The "Find Last Set Bit" (`fls` function of the C part of the kernel)

  operation.



A `num` core kernel module is being designed to provide these operations.



| Complexity: Intermediate

| Contact: Alexandre Courbot



Delay / Sleep abstractions [DLAY]

---------------------------------



Rust abstractions for the kernel's delay() and sleep() functions.
@@ -159,18 +205,6 @@ 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

-------------
@@ -179,12 +213,11 @@ capability, MSI API abstractions. 


| Complexity: Beginner



Auxiliary bus abstractions

--------------------------



Rust abstraction for the auxiliary bus APIs.

XArray bindings [XARR]

----------------------



This is needed to connect nova-core to the nova-drm driver.

We need bindings for `xa_alloc`/`xa_alloc_cyclic` in order to generate the

auxiliary device IDs.



| Complexity: Intermediate
@@ -216,15 +249,6 @@ 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

-----------------------
@@ -234,23 +258,6 @@ 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

-------------------

drivers/gpu/nova-core/dma.rs

+1 −1
Original line number Diff line number Diff line
@@ -26,7 +26,7 @@ pub(crate) fn new(dev: &device::Device<device::Bound>, len: usize) -> Result<Sel 


    pub(crate) fn from_data(dev: &device::Device<device::Bound>, data: &[u8]) -> Result<Self> {

        Self::new(dev, data.len()).map(|mut dma_obj| {

            // TODO: replace with `CoherentAllocation::write()` once available.

            // TODO[COHA]: replace with `CoherentAllocation::write()` once available.

            // SAFETY:

            // - `dma_obj`'s size is at least `data.len()`.

            // - We have just created this object and there is no other user at this stage.

drivers/gpu/nova-core/driver.rs

+1 −1
Original line number Diff line number Diff line
@@ -42,7 +42,7 @@ fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> Result<Pin<KBox<Self 
                _reg: auxiliary::Registration::new(

                    pdev.as_ref(),

                    c_str!("nova-drm"),

                    0, // TODO: Once it lands, use XArray; for now we don't use the ID.

                    0, // TODO[XARR]: Once it lands, use XArray; for now we don't use the ID.

                    crate::MODULE_NAME

                )?,

            }),

drivers/gpu/nova-core/falcon.rs

+7 −1
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ pub(crate) enum FalconCoreRev { 
    Rev7 = 7,

}



// TODO[FPRI]: replace with `FromPrimitive`.

impl TryFrom<u8> for FalconCoreRev {

    type Error = Error;
@@ -68,6 +69,7 @@ pub(crate) enum FalconCoreRevSubversion { 
    Subversion3 = 3,

}



// TODO[FPRI]: replace with `FromPrimitive`.

impl TryFrom<u8> for FalconCoreRevSubversion {

    type Error = Error;
@@ -101,6 +103,7 @@ pub(crate) enum FalconSecurityModel { 
    Heavy = 3,

}



// TODO[FPRI]: replace with `FromPrimitive`.

impl TryFrom<u8> for FalconSecurityModel {

    type Error = Error;
@@ -128,6 +131,7 @@ pub(crate) enum FalconModSelAlgo { 
    Rsa3k = 1,

}



// TODO[FPRI]: replace with `FromPrimitive`.

impl TryFrom<u8> for FalconModSelAlgo {

    type Error = Error;
@@ -148,6 +152,7 @@ pub(crate) enum DmaTrfCmdSize { 
    Size256B = 0x6,

}



// TODO[FPRI]: replace with `FromPrimitive`.

impl TryFrom<u8> for DmaTrfCmdSize {

    type Error = Error;
@@ -199,6 +204,7 @@ pub(crate) enum FalconFbifTarget { 
    NoncoherentSysmem = 2,

}



// TODO[FPRI]: replace with `FromPrimitive`.

impl TryFrom<u8> for FalconFbifTarget {

    type Error = Error;
@@ -354,7 +360,7 @@ fn reset_eng(&self, bar: &Bar0) -> Result { 


        regs::NV_PFALCON_FALCON_ENGINE::alter(bar, E::BASE, |v| v.set_reset(true));



        // TODO: replace with udelay() or equivalent once available.

        // TODO[DLAY]: replace with udelay() or equivalent once available.

        // TIMEOUT: falcon engine should not take more than 10us to reset.

        let _: Result = util::wait_on(Duration::from_micros(10), || None);

drivers/gpu/nova-core/falcon/hal/ga102.rs

+5 −5
Original line number Diff line number Diff line
@@ -42,10 +42,10 @@ fn signature_reg_fuse_version_ga102( 
    engine_id_mask: u16,

    ucode_id: u8,

) -> Result<u32> {

    // TODO: The ucode fuse versions are contained in the FUSE_OPT_FPF_<ENGINE>_UCODE<X>_VERSION

    // registers, which are an array. Our register definition macros do not allow us to manage them

    // properly, so we need to hardcode their addresses for now. Clean this up once we support

    // register arrays.

    // TODO[REGA]: The ucode fuse versions are contained in the

    // FUSE_OPT_FPF_<ENGINE>_UCODE<X>_VERSION registers, which are an array. Our register

    // definition macros do not allow us to manage them properly, so we need to hardcode their

    // addresses for now. Clean this up once we support register arrays.



    // Each engine has 16 ucode version registers numbered from 1 to 16.

    if ucode_id == 0 || ucode_id > 16 {
@@ -69,7 +69,7 @@ fn signature_reg_fuse_version_ga102( 
    let reg_fuse_version =

        bar.read32(reg_fuse_base + ((ucode_id - 1) as usize * core::mem::size_of::<u32>()));



    // TODO: replace with `last_set_bit` once it lands.

    // TODO[NUMM]: replace with `last_set_bit` once it lands.

    Ok(u32::BITS - reg_fuse_version.leading_zeros())

}