Commit c7125739 authored by Beata Michalska's avatar Beata Michalska Committed by Danilo Krummrich
Browse files

rust: dma: allow drivers to tune max segment size 



Make dma_set_max_seg_size() available to Rust so drivers can perform
standard DMA setup steps.

Signed-off-by: default avatarBeata Michalska <beata.michalska@arm.com>
Acked-by: default avatarRobin Murphy <robvin.murphy@arm.com>
Reviewed-by: default avatarAlice Ryhl <aliceryhl@google.com>
Link: https://patch.msgid.link/20260128135320.689046-1-beata.michalska@arm.com


Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
parent 7c60d964

rust/helpers/dma.c

+6 −0
Original line number Diff line number Diff line
@@ -43,3 +43,9 @@ size_t rust_helper_dma_max_mapping_size(struct device *dev) 
{

	return dma_max_mapping_size(dev);

}



__rust_helper void rust_helper_dma_set_max_seg_size(struct device *dev,

						    unsigned int size)

{

	dma_set_max_seg_size(dev, size);

}

rust/kernel/dma.rs

+17 −0
Original line number Diff line number Diff line
@@ -85,6 +85,23 @@ unsafe fn dma_set_mask_and_coherent(&self, mask: DmaMask) -> Result { 
            bindings::dma_set_mask_and_coherent(self.as_ref().as_raw(), mask.value())

        })

    }



    /// Set the maximum size of a single DMA segment the device may request.

    ///

    /// This method is usually called once from `probe()` as soon as the device capabilities are

    /// known.

    ///

    /// # Safety

    ///

    /// This method must not be called concurrently with any DMA allocation or mapping primitives,

    /// such as [`CoherentAllocation::alloc_attrs`].

    unsafe fn dma_set_max_seg_size(&self, size: u32) {

        // SAFETY:

        // - By the type invariant of `device::Device`, `self.as_ref().as_raw()` is valid.

        // - The safety requirement of this function guarantees that there are no concurrent calls

        //   to DMA allocation and mapping primitives using this parameter.

        unsafe { bindings::dma_set_max_seg_size(self.as_ref().as_raw(), size) }

    }

}



/// A DMA mask that holds a bitmask with the lowest `n` bits set.