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Date: Wed, 2 Jul 2025 12:36:13 +0200
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Subject: Re: [PATCH v11 4/4] rust: platform: allow ioremap of platform
 resources
To: Daniel Almeida <daniel.almeida@collabora.com>
Cc: Miguel Ojeda <ojeda@kernel.org>, Alex Gaynor <alex.gaynor@gmail.com>,
 Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
 =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>,
 Andreas Hindborg <a.hindborg@kernel.org>, Alice Ryhl <aliceryhl@google.com>,
 Trevor Gross <tmgross@umich.edu>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
 "Rafael J. Wysocki" <rafael@kernel.org>,
 Andrew Morton <akpm@linux-foundation.org>,
 Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
 =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>,
 Bjorn Helgaas <bhelgaas@google.com>,
 Mika Westerberg <mika.westerberg@linux.intel.com>,
 Ying Huang <huang.ying.caritas@gmail.com>, Benno Lossin <lossin@kernel.org>,
 linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org
References: <20250701-topics-tyr-platform_iomem-v11-0-6cd5d5061151@collabora.com>
 <20250701-topics-tyr-platform_iomem-v11-4-6cd5d5061151@collabora.com>
From: Danilo Krummrich <dakr@kernel.org>
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In-Reply-To: <20250701-topics-tyr-platform_iomem-v11-4-6cd5d5061151@collabora.com>
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On 7/1/25 4:34 PM, Daniel Almeida wrote:
> +impl Device<device::Bound> {

<snip>

> +    pub fn iomap_resource_sized<const SIZE: usize>(
> +        &self,
> +        resource: &Resource,
> +    ) -> Result<impl PinInit<Devres<IoMem<SIZE>>, Error> + '_> {
> +        IoMem::new(resource, self.as_ref())
> +    }

Sorry that I did not catch this earlier, but what if I supply a Resource here
that has *not* been obtained by any of the platform::Device methods and from the
same platform::Device as you call this function for?

I think this also needs something similar to what we do in the IRQ abstraction,
e.g.:

	/// # Invariants
	///
	/// `res` has been obtained from `dev`.
	pub struct IoRequest<'a> {
	   dev: &'a Device<Bound>,
	   res: &'a Resource,
	}

Such that IoMem::new() can take an IoRequest instance instead.