dma.rs

 1// SPDX-License-Identifier: GPL-2.0
 2
 3//! Simple DMA object wrapper.
 4
 5use core::ops::{
 6    Deref,
 7    DerefMut, //
 8};
 9
10use kernel::{
11    device,
12    dma::CoherentAllocation,
13    page::PAGE_SIZE,
14    prelude::*, //
15};
16
17pub(crate) struct DmaObject {
18    dma: CoherentAllocation<u8>,
19}
20
21impl DmaObject {
22    pub(crate) fn new(dev: &device::Device<device::Bound>, len: usize) -> Result<Self> {
23        let len = core::alloc::Layout::from_size_align(len, PAGE_SIZE)
24            .map_err(|_| EINVAL)?
25            .pad_to_align()
26            .size();
27        let dma = CoherentAllocation::alloc_coherent(dev, len, GFP_KERNEL | __GFP_ZERO)?;
28
29        Ok(Self { dma })
30    }
31
32    pub(crate) fn from_data(dev: &device::Device<device::Bound>, data: &[u8]) -> Result<Self> {
33        Self::new(dev, data.len()).and_then(|mut dma_obj| {
34            // SAFETY: We have just allocated the DMA memory, we are the only users and
35            // we haven't made the device aware of the handle yet.
36            unsafe { dma_obj.write(data, 0)? }
37            Ok(dma_obj)
38        })
39    }
40}
41
42impl Deref for DmaObject {
43    type Target = CoherentAllocation<u8>;
44
45    fn deref(&self) -> &Self::Target {
46        &self.dma
47    }
48}
49
50impl DerefMut for DmaObject {
51    fn deref_mut(&mut self) -> &mut Self::Target {
52        &mut self.dma
53    }
54}