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Message-Id: <20250623-topics-tyr-platform_iomem-v10-4-ed860a562940@collabora.com>
Date: Mon, 23 Jun 2025 15:01:01 -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>,
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>,
Andrew Morton <akpm@...ux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
Ying Huang <huang.ying.caritas@...il.com>, Benno Lossin <lossin@...nel.org>
Cc: linux-kernel@...r.kernel.org, rust-for-linux@...r.kernel.org,
Daniel Almeida <daniel.almeida@...labora.com>
Subject: [PATCH v10 4/4] rust: platform: allow ioremap of platform
resources
The preceding patches added support for resources, and for a general
IoMem abstraction, but thus far there is no way to access said IoMem
from drivers, as its creation is unsafe and depends on a resource that
must be acquired from some device first.
Now, allow the ioremap of platform resources themselves, thereby making
the IoMem available to platform drivers.
Signed-off-by: Daniel Almeida <daniel.almeida@...labora.com>
---
rust/kernel/platform.rs | 120 +++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 118 insertions(+), 2 deletions(-)
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index 0eedb8239fec31df7ab64dc68d220c9d965f1f21..5e787cf85f41722837bb34a6620c92d13d55625b 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -5,9 +5,14 @@
//! C header: [`include/linux/platform_device.h`](srctree/include/linux/platform_device.h)
use crate::{
- bindings, container_of, device, driver,
+ bindings, container_of, device,
+ devres::Devres,
+ driver,
error::{to_result, Result},
- io::Resource,
+ io::{
+ mem::{ExclusiveIoMem, IoMem},
+ Resource,
+ },
of,
prelude::*,
str::CStr,
@@ -228,6 +233,117 @@ pub fn resource_by_name(&self, name: &CStr) -> Option<&Resource> {
}
}
+impl Device<device::Bound> {
+ /// Maps a platform resource where the size is known at compile time.
+ ///
+ /// This uses the
+ /// [`ioremap()`](https://docs.kernel.org/driver-api/device-io.html#getting-access-to-the-device)
+ /// C API.
+ ///
+ /// # Examples
+ ///
+ /// ```no_run
+ /// # use kernel::{bindings, c_str, platform, of, device::Core};
+ /// # struct SampleDriver;
+ ///
+ /// impl platform::Driver for SampleDriver {
+ /// # type IdInfo = ();
+ /// # const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
+ ///
+ /// fn probe(
+ /// pdev: &platform::Device<Core>,
+ /// info: Option<&Self::IdInfo>,
+ /// ) -> Result<Pin<KBox<Self>>> {
+ /// let offset = 0; // Some offset.
+ ///
+ /// // If the size is known at compile time, use [`Self::iomap_resource_sized`].
+ /// //
+ /// // No runtime checks will apply when reading and writing.
+ /// let resource = pdev.resource_by_index(0).ok_or(ENODEV)?;
+ /// let iomem = pdev.iomap_resource_sized::<42>(&resource)?;
+ /// let io = iomem.access(pdev.as_ref())?;
+ ///
+ /// // Read and write a 32-bit value at `offset`.
+ /// let data = io.read32_relaxed(offset);
+ ///
+ /// io.write32_relaxed(data, offset);
+ ///
+ /// # Ok(KBox::new(SampleDriver, GFP_KERNEL)?.into())
+ /// }
+ /// }
+ /// ```
+ pub fn iomap_resource_sized<const SIZE: usize>(
+ &self,
+ resource: &Resource,
+ ) -> Result<Devres<IoMem<SIZE>>> {
+ IoMem::new(resource, self.as_ref())
+ }
+
+ /// Same as [`Self::iomap_resource_sized`] but with exclusive access to the
+ /// underlying region.
+ ///
+ /// This uses the
+ /// [`ioremap()`](https://docs.kernel.org/driver-api/device-io.html#getting-access-to-the-device)
+ /// C API.
+ pub fn iomap_resource_exclusive_sized<const SIZE: usize>(
+ &self,
+ resource: &Resource,
+ ) -> Result<Devres<ExclusiveIoMem<SIZE>>> {
+ ExclusiveIoMem::new(resource, self.as_ref())
+ }
+
+ /// Maps a platform resource through `iomap()`.
+ ///
+ /// This uses the
+ /// [`ioremap()`](https://docs.kernel.org/driver-api/device-io.html#getting-access-to-the-device)
+ /// C API.
+ ///
+ /// # Examples
+ ///
+ /// ```no_run
+ /// # use kernel::{bindings, c_str, platform, of, device::Core};
+ /// # struct SampleDriver;
+ ///
+ /// impl platform::Driver for SampleDriver {
+ /// # type IdInfo = ();
+ /// # const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
+ ///
+ /// fn probe(
+ /// pdev: &platform::Device<Core>,
+ /// info: Option<&Self::IdInfo>,
+ /// ) -> Result<Pin<KBox<Self>>> {
+ /// let offset = 0; // Some offset.
+ ///
+ /// // Unlike [`Self::iomap_resource_sized`], here the size of the memory region
+ /// // is not known at compile time, so only the `try_read*` and `try_write*`
+ /// // family of functions should be used, leading to runtime checks on every
+ /// // access.
+ /// let resource = pdev.resource_by_index(0).ok_or(ENODEV)?;
+ /// let iomem = pdev.iomap_resource(&resource)?;
+ /// let io = iomem.access(pdev.as_ref())?;
+ ///
+ /// let data = io.try_read32_relaxed(offset)?;
+ ///
+ /// io.try_write32_relaxed(data, offset)?;
+ ///
+ /// # Ok(KBox::new(SampleDriver, GFP_KERNEL)?.into())
+ /// }
+ /// }
+ /// ```
+ pub fn iomap_resource(&self, resource: &Resource) -> Result<Devres<IoMem<0>>> {
+ self.iomap_resource_sized::<0>(resource)
+ }
+
+ /// Same as [`Self::iomap_resource`] but with exclusive access to the underlying
+ /// region.
+ pub fn iomap_resource_exclusive(
+ &self,
+ resource: &Resource,
+ ) -> Result<Devres<ExclusiveIoMem<0>>> {
+ self.iomap_resource_exclusive_sized::<0>(resource)
+ }
+}
+
// SAFETY: `Device` is a transparent wrapper of a type that doesn't depend on `Device`'s generic
// argument.
kernel::impl_device_context_deref!(unsafe { Device });
--
2.50.0
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