Message-Id: <20250717-topics-tyr-platform_iomem-v15-0-beca780b77e3@collabora.com>
Date: Thu, 17 Jul 2025 12:55:21 -0300
From: Daniel Almeida <daniel.almeida@...labora.com>
To: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>, 
 Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, 
 Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
 Benno Lossin <lossin@...nel.org>, Andreas Hindborg <a.hindborg@...nel.org>, 
 Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>, 
 Danilo Krummrich <dakr@...nel.org>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 "Rafael J. Wysocki" <rafael@...nel.org>
Cc: linux-kernel@...r.kernel.org, rust-for-linux@...r.kernel.org, 
 Fiona Behrens <me@...enk.dev>, 
 Daniel Almeida <daniel.almeida@...labora.com>
Subject: [PATCH v15 0/3] rust: platform: add Io support

Changes in v15:
- Use a default string in ioremap() if the resource doesn't have a name
- Fix the doctests in mem.rs to use the new name for io_request_by_*
- Link to v14: https://lore.kernel.org/r/20250716-topics-tyr-platform_iomem-v14-0-2c2709135cb2@collabora.com

Changes in v14:
- Changed Resource::size() to return ResourceSize instead of u64 (Alice)
- Changed Resource::name() to return a non-static lifetime (i.e.: the
  lifetime of &self). It turns out that although this value tends to often
  point to string literals, this value is not necessarily static  in C.
  (Thanks for bringing this up, Alice)
- "name" is now owned by the Region. We were storing Resource::name()
  previously as that was 'static, but that is not the case anymore. The
  string is now copied from Resource::name() instead. If there is no name,
  we fail.
- Changed Resource::name() to return an Option, as the name may be NULL in
  C (see the DEFINE_RES_* family of macros in C)
- Added a TODO to the "size" cast in IoMem::ioremap(), noting that we
  should fix this in C in the future (Thanks, Alice)
- Casting "size" in IoMem::ioremap() only once now (thanks, Alice)
- Introduced Flags::new(), which derives from a comment in the request_irq
  series. This introduces a build_assert to reduce the number of casts.
- Added Alice's r-b to patches 1-2
- Added Miguel's a-b to patches 1-3 (Given in v11 and forgotten)
- Link to v13: https://lore.kernel.org/r/20250711-topics-tyr-platform_iomem-v13-0-06328b514db3@collabora.com

Changes in v13:
- Change ResourceSize to just be bindings::phys_addr_t (Danilo)
- Mention that ResourceSize can be 32bits even on 64bit architectures (Alice)
- Use the deref impl for Resource to avoid unsafe (Alice)
- Change Resource::as_ref() to Resource::from_raw() (Alice)
- Mention that it's ok for __request_region to store the name as we require
  it to be 'static
- Remove all instances of core::ffi::* as these are in the prelude already
  (Alice)
- Resource::start() and Resoruce::flags() do not copy &self anymore (Alice)
- Define the resource::Flags constants within impl Flags itself (Alice)
- Apply the diff from Danilo to return impl PinInit<...> instead of
  Result<impl PinInin<...>> from the iomap() functions.
- Fix the docs in patch 2 (Alice)
- Use try_into() instead of blindly casting ResourceSize to usize (Alice)
- Rename request_io_by{index,name} to io_request_by{index,name} (Danilo)
- Link to v12: https://lore.kernel.org/rust-for-linux/20250704-topics-tyr-platform_iomem-v12-0-1d3d4bd8207d@collabora.com/

Changes in v12:
- Fixed the typos that Miguel pointed out in resource.rs
- Fixed a typo where thread was written as thead
- Removed ioport_resource() and iomem_resource() (Danilo)
- Created IoRequest<'a> and gave it an unsafe constructor (Danilo)
- Moved all the logic to map resources from platform.rs to IoRequest.
- Dropped the last patch as a result of the above.
- Link to v11: https://lore.kernel.org/r/20250701-topics-tyr-platform_iomem-v11-0-6cd5d5061151@collabora.com

Changes in v11:
- Rebased on top of driver-core-next (to get the latest Devres changes)
- Changed the order between requesting the resource and mapping it
  (Danilo)
- Link to v10: https://lore.kernel.org/r/20250623-topics-tyr-platform_iomem-v10-0-ed860a562940@collabora.com

Changes in v10:
- Rebased on driver-core-next
- Fixed examples (they were still using try_access())
- Removed map_err() from the examples, as it was not needed.
- Added a pub use for Resource in io.rs
- Reworked the platform code to make use of the pub use above
- Link to v9: https://lore.kernel.org/r/20250603-topics-tyr-platform_iomem-v9-0-a27e04157e3e@collabora.com

Changes in v9:
- Rebased on top of nova-next (for Devres::access())
- Reworked the documentation to add more markdown.
- Converted to &raw mut instead of addr_of_mut!()
- Renamed 'from_ptr' to 'as_ref' for consistency
- Changed the IoMem examples to use the signature for probe()
- Changed resource() to resource_by_index(). It's a better fit given
  the existance of resource_by_name().
- Created a separate patch for the resource accessors above.
- Moved the accessors into the generic impl block, so they work with all
  Device contexts.
- Take Device<Bound> where applicable
- Renamed "ioremap_*" to "iomap_*", in order to be consistent with the code
  in pci.rs
- Switched to Devres::access()
- Link to v8: https://lore.kernel.org/r/20250509-topics-tyr-platform_iomem-v8-0-e9f1725a40da@collabora.com

rust: platform: add Io support

Changes in v8:
- Rebased on driver-core-next
- Opted to wait for 'rust/revocable: add try_with() convenience method' to
  land instead of using the suggested closure (let me know if we should
  just switch to the closure anyways)
- Cc'd more people
- Link to v7: https://lore.kernel.org/r/20250318-topics-tyr-platform_iomem-v7-0-7438691d9ef7@collabora.com

Changes in v7:

- Rebased on top of rust-next
- Fixed a few Clippy lints
- Fixed typos (Thanks Daniel!)
- "struct Flags" now contains a usize (thanks Daniel)
- Fixed "Doc list without indentation" warning (thanks, Guangbo)

Thanks, Fiona {
- Removed RequestFn, as all functions simply used request_region and RequestFn
  had issues. Only request_region() is exposed now.
- Gated iomem_resource on CONFIG_HAS_IOMEM
- Require that the name argument be 'static
}

- Correctly check for IORESOURCE_MEM_NONPOSTED. We now call ioremap_np if that
  is set (thanks, Lina!)
- Remove #[dead_code] attribute from ExclusiveIoMem::region.

Changes in v6:

- Added Fiona as co-developer in the first patch, as I merged part of her code
from the LED driver series (thanks, Fiona)

- (Fiona) added the ResourceSize type, thereby fixing the u32 vs u64 issues
  pointed out by Christian

- Moved the request_region, release_region and friends to resource.rs

- Added the Region type. This type represents a resource returned by
  `request_region` and friends. It is also owned, representing the fact
  that the region remains marked as busy until release_region is called on
  drop. (Thanks Alice, for pointing out this pattern)

- Rewrote the IoMem abstraction to implement a separate type for exclusive
  access to an underlying region. I really disliked the `EXCLUSIVE` const
  generic, as it was definitely not ergonomic, i.e.:

  `IoMem<0, false>`

  ...doesn't really say much. In fact, I believe that boolean parameters
  hurt readability in general.

  This new approach lets users build either regular IoMem's, which basically
  call ioremap under the covers, and ExclusiveIoMem's , which also call request_region
  via the Region type.

- Added access to the ioresource_port and ioresource_mem globals.

Link to v5: https://lore.kernel.org/rust-for-linux/20250116125632.65017-1-daniel.almeida@collabora.com/

Changes in v5:

- resend v5, as the r4l list was not cc'd
- use srctree where applicable in the docs (Alice)
- Remove 'mut' in Resource::from_ptr() (Alice)
- Add 'invariants' section for Resource (Alice)
- Fix typos in mem.rs (Alice)
- Turn 'exclusive' into a const generic (Alice)
- Fix example in platform.rs (Alice)
- Rework the resource.is_null() check (Alice)
- Refactor IoMem::new() to return DevRes<IoMem> directly (Danilo)

link to v4: https://lore.kernel.org/rust-for-linux/20250109133057.243751-1-daniel.almeida@collabora.com/

Changes in v4:

- Rebased on top of driver-core-next
- Split series in multiple patches (Danilo)
- Move IoMem and Resource into its own files (Danilo)
- Fix a missing "if exclusive {...}" check (Danilo)
- Fixed the example, since it was using the old API (Danilo)
- Use Opaque in `Resource`, instead of NonNull and PhantomData (Boqun)
- Highlight that non-exclusive access to the iomem might be required in some cases
- Fixed the safety comment in IoMem::deref()

Link to v3: https://lore.kernel.org/rust-for-linux/20241211-topic-panthor-rs-platform_io_support-v3-1-08ba707e5e3b@collabora.com/

Changes in v3:
- Rebased on top of v5 for the PCI/Platform abstractions
- platform_get_resource is now called only once when calling ioremap
- Introduced a platform::Resource type, which is bound to the lifetime of the
 platform Device
- Allow retrieving resources from the platform device either by index or
 name
- Make request_mem_region() optional
- Use resource.name() in request_mem_region
- Reword the example to remove an unaligned, out-of-bounds offset
- Update the safety requirements of platform::IoMem

Changes in v2:
- reworked the commit message
- added missing request_mem_region call (Thanks Alice, Danilo)
- IoMem::new() now takes the platform::Device, the resource number and
 the name, instead of an address and a size (thanks, Danilo)
- Added a new example for both sized and unsized versions of IoMem.
- Compiled the examples using kunit.py (thanks for the tip, Alice!)
- Removed instances of `foo as _`. All `as` casts now spell out the actual
 type.
- Now compiling with CLIPPY=1 (I realized I had forgotten, sorry)
- Rebased on top of rust-next to check for any warnings given the new
 unsafe lints.

---
Daniel Almeida (3):
      rust: io: add resource abstraction
      rust: io: mem: add a generic iomem abstraction
      rust: platform: add resource accessors

 rust/bindings/bindings_helper.h |   1 +
 rust/helpers/io.c               |  41 ++++++
 rust/kernel/io.rs               |   5 +
 rust/kernel/io/mem.rs           | 283 ++++++++++++++++++++++++++++++++++++++++
 rust/kernel/io/resource.rs      | 229 ++++++++++++++++++++++++++++++++
 rust/kernel/platform.rs         |  60 ++++++++-
 6 files changed, 618 insertions(+), 1 deletion(-)
---
base-commit: f5d3ef25d238901a76fe0277787afa44f7714739
change-id: 20250318-topics-tyr-platform_iomem-1710a177e1df

Best regards,
-- 
Daniel Almeida <daniel.almeida@...labora.com>

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