sel4_virtio_hal_impl/
lib.rs

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1//
2// Copyright 2023, Colias Group, LLC
3//
4// SPDX-License-Identifier: BSD-2-Clause
5//
6
7#![no_std]
8
9use core::alloc::Layout;
10use core::ptr::{self, NonNull};
11
12use one_shot_mutex::sync::OneShotMutex;
13use virtio_drivers::{BufferDirection, Hal, PhysAddr, PAGE_SIZE};
14
15use sel4_abstract_allocator::basic::BasicAllocator;
16use sel4_abstract_allocator::{ByRange, WithAlignmentBound};
17use sel4_immediate_sync_once_cell::ImmediateSyncOnceCell;
18use sel4_shared_memory::SharedMemoryRef;
19
20static GLOBAL_STATE: ImmediateSyncOnceCell<OneShotMutex<State>> = ImmediateSyncOnceCell::new();
21
22struct State {
23    dma_region: SharedMemoryRef<'static, [u8]>,
24    dma_region_paddr: usize,
25    bounce_buffer_allocator: ByRange<WithAlignmentBound<BasicAllocator>>,
26}
27
28impl State {
29    fn offset_to_paddr(&self, offset: usize) -> PhysAddr {
30        self.dma_region_paddr.checked_add(offset).unwrap()
31    }
32
33    fn paddr_to_offset(&self, paddr: PhysAddr) -> usize {
34        paddr.checked_sub(self.dma_region_paddr).unwrap()
35    }
36}
37
38pub struct HalImpl;
39
40impl HalImpl {
41    pub fn init(dma_region_size: usize, dma_region_vaddr: usize, dma_region_paddr: usize) {
42        let dma_region_ptr = NonNull::new(ptr::slice_from_raw_parts_mut(
43            dma_region_vaddr as *mut _,
44            dma_region_size,
45        ))
46        .unwrap();
47
48        let dma_region = unsafe { SharedMemoryRef::new(dma_region_ptr) };
49
50        let max_alignment = 1
51            << dma_region_vaddr
52                .trailing_zeros()
53                .min(dma_region_paddr.trailing_zeros());
54
55        let bounce_buffer_allocator = ByRange::new(WithAlignmentBound::new(
56            BasicAllocator::new(dma_region_size),
57            max_alignment,
58        ));
59
60        GLOBAL_STATE
61            .set(OneShotMutex::new(State {
62                dma_region,
63                dma_region_paddr,
64                bounce_buffer_allocator,
65            }))
66            .ok()
67            .unwrap();
68    }
69}
70
71unsafe impl Hal for HalImpl {
72    fn dma_alloc(pages: usize, _direction: BufferDirection) -> (PhysAddr, NonNull<u8>) {
73        let mut state = GLOBAL_STATE.get().unwrap().lock();
74        assert!(pages > 0);
75        let layout = Layout::from_size_align(pages * PAGE_SIZE, PAGE_SIZE).unwrap();
76        let bounce_buffer_range = state.bounce_buffer_allocator.allocate(layout).unwrap();
77        let bounce_buffer_ptr = state
78            .dma_region
79            .as_mut_ptr()
80            .index(bounce_buffer_range.clone());
81        bounce_buffer_ptr.fill(0);
82        let vaddr = bounce_buffer_ptr.as_raw_ptr().cast::<u8>();
83        let paddr = state.offset_to_paddr(bounce_buffer_range.start);
84        (paddr, vaddr)
85    }
86
87    unsafe fn dma_dealloc(paddr: PhysAddr, _vaddr: NonNull<u8>, pages: usize) -> i32 {
88        let mut state = GLOBAL_STATE.get().unwrap().lock();
89        let bounce_buffer_range = {
90            let start = state.paddr_to_offset(paddr);
91            let size = pages * PAGE_SIZE;
92            start..(start + size)
93        };
94        state
95            .bounce_buffer_allocator
96            .deallocate(bounce_buffer_range);
97        0
98    }
99
100    unsafe fn mmio_phys_to_virt(_paddr: PhysAddr, _size: usize) -> NonNull<u8> {
101        panic!()
102    }
103
104    unsafe fn share(buffer: NonNull<[u8]>, _direction: BufferDirection) -> PhysAddr {
105        let mut state = GLOBAL_STATE.get().unwrap().lock();
106        assert!(!buffer.is_empty());
107        let layout = Layout::from_size_align(buffer.len(), 1).unwrap();
108        let bounce_buffer_range = state.bounce_buffer_allocator.allocate(layout).unwrap();
109        state
110            .dma_region
111            .as_mut_ptr()
112            .index(bounce_buffer_range.clone())
113            .copy_from_slice(buffer.as_ref());
114        state.offset_to_paddr(bounce_buffer_range.start)
115    }
116
117    unsafe fn unshare(paddr: PhysAddr, mut buffer: NonNull<[u8]>, direction: BufferDirection) {
118        let mut state = GLOBAL_STATE.get().unwrap().lock();
119        let bounce_buffer_range = {
120            let start = state.paddr_to_offset(paddr);
121            start..(start + buffer.len())
122        };
123        if direction != BufferDirection::DriverToDevice {
124            state
125                .dma_region
126                .as_mut_ptr()
127                .index(bounce_buffer_range.clone())
128                .copy_into_slice(buffer.as_mut());
129        }
130        state
131            .bounce_buffer_allocator
132            .deallocate(bounce_buffer_range);
133    }
134}
sel4_virtio_hal_impl/lib.rs

sel4_virtio_hal_impl/
lib.rs
