[PATCH v7 0/3] rust: platform: add Io support

Daniel Almeida
2025-03-18T17:21:28Z

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: allow ioremap of platform resources

rust/bindings/bindings_helper.h | 1 +
rust/helpers/io.c | 36 +++++
rust/kernel/io.rs | 3 +
rust/kernel/io/mem.rs | 125 ++++++++++++++++
rust/kernel/io/resource.rs | 252 ++++++++++++++++++++++++++++++++
rust/kernel/platform.rs | 123 +++++++++++++++-
6 files changed, 539 insertions(+), 1 deletion(-)
create mode 100644 rust/kernel/io/mem.rs
create mode 100644 rust/kernel/io/resource.rs

--
2.48.0

---
Daniel Almeida (3):
rust: io: add resource abstraction
rust: io: mem: add a generic iomem abstraction
rust: platform: allow ioremap of platform resources

rust/bindings/bindings_helper.h | 1 +
rust/helpers/io.c | 41 ++++++++
rust/kernel/io.rs | 3 +
rust/kernel/io/mem.rs | 141 +++++++++++++++++++++++++
rust/kernel/io/resource.rs | 222 ++++++++++++++++++++++++++++++++++++++++
rust/kernel/platform.rs | 123 +++++++++++++++++++++-
6 files changed, 530 insertions(+), 1 deletion(-)
---
base-commit: cf25bc61f8aecad9b0c45fe32697e35ea4b13378
change-id: 20250318-topics-tyr-platform_iomem-1710a177e1df

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