Re: [PATCH] rust: platform: add Io support

[Alice Ryhl]

On Thu, Oct 24, 2024 at 4:20 PM Daniel Almeida
<daniel.almeida@xxxxxxxxxxxxx> wrote:
> +    /// Maps a platform resource through ioremap() where the size is known at
> +    /// compile time.
> +    pub fn ioremap_resource_sized<const SIZE: usize>(
> +        &self,
> +        resource: u32,
> +    ) -> Result<Devres<IoMem<SIZE>>> {
> +        let res = self.resource(resource)?;
> +        let size = self.resource_len(resource)? as usize;
> +
> +        // SAFETY: `res` is guaranteed to be a valid MMIO address and the size
> +        // is given by the kernel as per `self.resource_len()`.
> +        let io = unsafe { IoMem::new(res as _, size) }?;

This cast looks wrong to me. You're taking a pointer to `struct
resource` and casting that to an MMIO address? Shouldn't the address
be (*res).start?

Danilo already mentioned this, but I think you're missing a call to
`request_mem_region` as well.

> +        let devres = Devres::new(self.as_ref(), io, GFP_KERNEL)?;

What purpose does the Devres serve?

Alice