linux-kernel - [PATCH 1/2] rust: Add dma_set_mask() and dma_set_coherent

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Message-ID: <20250708060451.398323-1-apopple@nvidia.com>
Date: Tue,  8 Jul 2025 16:04:50 +1000
From: Alistair Popple <apopple@...dia.com>
To: rust-for-linux@...r.kernel.org
Cc: Alistair Popple <apopple@...dia.com>,
	Danilo Krummrich <dakr@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	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>,
	Benno Lossin <lossin@...nel.org>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Trevor Gross <tmgross@...ch.edu>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	John Hubbard <jhubbard@...dia.com>,
	Alexandre Courbot <acourbot@...dia.com>,
	linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] rust: Add dma_set_mask() and dma_set_coherent_mask() bindings

Add bindings to allow setting the DMA masks for both a generic device
and a PCI device.

Signed-off-by: Alistair Popple <apopple@...dia.com>
Cc: Danilo Krummrich <dakr@...nel.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: "Krzysztof Wilczyński" <kwilczynski@...nel.org>
Cc: Miguel Ojeda <ojeda@...nel.org>
Cc: Alex Gaynor <alex.gaynor@...il.com>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Gary Guo <gary@...yguo.net>
Cc: "Björn Roy Baron" <bjorn3_gh@...tonmail.com>
Cc: Benno Lossin <lossin@...nel.org>
Cc: Andreas Hindborg <a.hindborg@...nel.org>
Cc: Alice Ryhl <aliceryhl@...gle.com>
Cc: Trevor Gross <tmgross@...ch.edu>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: John Hubbard <jhubbard@...dia.com>
Cc: Alexandre Courbot <acourbot@...dia.com>
Cc: linux-pci@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
---
 rust/kernel/device.rs | 25 +++++++++++++++++++++++++
 rust/kernel/pci.rs    | 23 +++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index dea06b79ecb5..77a1293a1c82 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -10,6 +10,7 @@
     types::{ARef, Opaque},
 };
 use core::{fmt, marker::PhantomData, ptr};
+use kernel::prelude::*;
 
 #[cfg(CONFIG_PRINTK)]
 use crate::c_str;
@@ -67,6 +68,30 @@ pub(crate) fn as_raw(&self) -> *mut bindings::device {
         self.0.get()
     }
 
+    /// Sets the DMA mask for the device.
+    pub fn dma_set_mask(&self, mask: u64) -> Result {
+        // SAFETY: By the type invariant of `device::Device`, `self.as_ref().as_raw()` is valid.
+        let ret = unsafe { bindings::dma_set_mask(&(*self.as_raw()) as *const _ as *mut _, mask) };
+        if ret != 0 {
+            Err(Error::from_errno(ret))
+        } else {
+            Ok(())
+        }
+    }
+
+    /// Sets the coherent DMA mask for the device.
+    pub fn dma_set_coherent_mask(&self, mask: u64) -> Result {
+        // SAFETY: By the type invariant of `device::Device`, `self.as_ref().as_raw()` is valid.
+        let ret = unsafe {
+            bindings::dma_set_coherent_mask(&(*self.as_raw()) as *const _ as *mut _, mask)
+        };
+        if ret != 0 {
+            Err(Error::from_errno(ret))
+        } else {
+            Ok(())
+        }
+    }
+
     /// Returns a reference to the parent device, if any.
     #[cfg_attr(not(CONFIG_AUXILIARY_BUS), expect(dead_code))]
     pub(crate) fn parent(&self) -> Option<&Self> {
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index 8435f8132e38..7f640ba8f19c 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -369,6 +369,17 @@ fn as_raw(&self) -> *mut bindings::pci_dev {
     }
 }
 
+impl<'a, Ctx: device::DeviceContext> From<&'a kernel::pci::Device<Ctx>>
+    for &'a device::Device<Ctx>
+{
+    fn from(pdev: &kernel::pci::Device<Ctx>) -> &device::Device<Ctx> {
+        // SAFETY: The returned reference has the same lifetime as the
+        // pci::Device which holds a reference on the underlying device
+        // pointer.
+        unsafe { device::Device::as_ref(&(*pdev.as_raw()).dev as *const _ as *mut _) }
+    }
+}
+
 impl Device {
     /// Returns the PCI vendor ID.
     pub fn vendor_id(&self) -> u16 {
@@ -393,6 +404,18 @@ pub fn resource_len(&self, bar: u32) -> Result<bindings::resource_size_t> {
         // - by its type invariant `self.as_raw` is always a valid pointer to a `struct pci_dev`.
         Ok(unsafe { bindings::pci_resource_len(self.as_raw(), bar.try_into()?) })
     }
+
+    /// Set the DMA mask for PCI device.
+    pub fn dma_set_mask(&self, mask: u64) -> Result {
+        let dev: &device::Device = self.into();
+        dev.dma_set_mask(mask)
+    }
+
+    /// Set the coherent DMA mask for the PCI device.
+    pub fn dma_set_coherent_mask(&self, mask: u64) -> Result {
+        let dev: &device::Device = self.into();
+        dev.dma_set_coherent_mask(mask)
+    }
 }
 
 impl Device<device::Bound> {
-- 
2.47.2