Re: [PATCH v6 7/8] rust: Introduce iosys_map bindings

["Danilo Krummrich" <dakr@kernel.org>]

(Cc: Zhi, Matt, Alex)

On Tue Dec 2, 2025 at 11:03 PM CET, Lyude Paul wrote:
> This introduces a set of bindings for working with iosys_map in rust code.
> The design of this is heavily based off the design for both the io and
> dma_map bindings for Rust.

I already had a chat with Lyude about this, but also want to post it here. I
have mainly two comment on this:

  (1) The backing memory of iosys_map may be a device resource and hence has to
      be protected against (bus) device / driver unbind.

  (2) The idea for the generic I/O infrastructure is to support arbitrary I/O
      backends rather than only MMIO. For instance, this can also be PCI
      configuration space, I2C, SPI, etc., but also DMA, VRAM, system memory,
      etc.

      For this, there is a patch series from Zhi [1] splitting up the current
      I/O structures into traits that we will land soon.

      We will also have macros analogous to dma_read!() and dma_write!() for the
      generic I/O infrastructure, which Matt also works on for his QC SoC
      driver.

      This will allow us to unify all kinds of I/O operations into a single
      interface, supporting the read!() and write!() accessors for values, the
      register!() macro and raw accessors, such as e.g. read32().

      With this we will have something that is way more powerful than iosys_map
      and makes this abstraction obsolete.

So instead of introducing an abstraction for iosys_map we should just implement
the corresponding I/O backends based on [1].

[1] https://lore.kernel.org/all/20260113092253.220346-3-zhiw@nvidia.com/