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Diffstat (limited to 'vendor/redox_syscall/src/io/dma.rs')
| -rw-r--r-- | vendor/redox_syscall/src/io/dma.rs | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/vendor/redox_syscall/src/io/dma.rs b/vendor/redox_syscall/src/io/dma.rs new file mode 100644 index 000000000..b356c8abe --- /dev/null +++ b/vendor/redox_syscall/src/io/dma.rs @@ -0,0 +1,200 @@ +use core::mem::{self, MaybeUninit}; +use core::ops::{Deref, DerefMut}; +use core::{ptr, slice}; + +use crate::Result; +use crate::{PartialAllocStrategy, PhysallocFlags}; + +/// An RAII guard of a physical memory allocation. Currently all physically allocated memory are +/// page-aligned and take up at least 4k of space (on x86_64). +#[derive(Debug)] +pub struct PhysBox { + address: usize, + size: usize +} + +impl PhysBox { + /// Construct a PhysBox from an address and a size. + /// + /// # Safety + /// This function is unsafe because when dropping, Self has to a valid allocation. + pub unsafe fn from_raw_parts(address: usize, size: usize) -> Self { + Self { + address, + size, + } + } + + /// Retrieve the byte address in physical memory, of this allocation. + pub fn address(&self) -> usize { + self.address + } + + /// Retrieve the size in bytes of the alloc. + pub fn size(&self) -> usize { + self.size + } + + /// Allocate physical memory that must reside in 32-bit space. + pub fn new_in_32bit_space(size: usize) -> Result<Self> { + Self::new_with_flags(size, PhysallocFlags::SPACE_32) + } + + pub fn new_with_flags(size: usize, flags: PhysallocFlags) -> Result<Self> { + assert!(!flags.contains(PhysallocFlags::PARTIAL_ALLOC)); + + let address = unsafe { crate::physalloc2(size, flags.bits())? }; + Ok(Self { + address, + size, + }) + } + + /// "Partially" allocate physical memory, in the sense that the allocation may be smaller than + /// expected, but still with a minimum limit. This is particularly useful when the physical + /// memory space is fragmented, and a device supports scatter-gather I/O. In that case, the + /// driver can optimistically request e.g. 1 alloc of 1 MiB, with the minimum of 512 KiB. If + /// that first allocation only returns half the size, the driver can do another allocation + /// and then let the device use both buffers. + pub fn new_partial_allocation(size: usize, flags: PhysallocFlags, strategy: Option<PartialAllocStrategy>, mut min: usize) -> Result<Self> { + debug_assert!(!(flags.contains(PhysallocFlags::PARTIAL_ALLOC) && strategy.is_none())); + + let address = unsafe { crate::physalloc3(size, flags.bits() | strategy.map(|s| s as usize).unwrap_or(0), &mut min)? }; + Ok(Self { + address, + size: min, + }) + } + + pub fn new(size: usize) -> Result<Self> { + let address = unsafe { crate::physalloc(size)? }; + Ok(Self { + address, + size, + }) + } +} + +impl Drop for PhysBox { + fn drop(&mut self) { + let _ = unsafe { crate::physfree(self.address, self.size) }; + } +} + +pub struct Dma<T: ?Sized> { + phys: PhysBox, + virt: *mut T, +} + +impl<T> Dma<T> { + pub fn from_physbox_uninit(phys: PhysBox) -> Result<Dma<MaybeUninit<T>>> { + let virt = unsafe { crate::physmap(phys.address, phys.size, crate::PHYSMAP_WRITE)? } as *mut MaybeUninit<T>; + + Ok(Dma { + phys, + virt, + }) + } + pub fn from_physbox_zeroed(phys: PhysBox) -> Result<Dma<MaybeUninit<T>>> { + let this = Self::from_physbox_uninit(phys)?; + unsafe { ptr::write_bytes(this.virt as *mut MaybeUninit<u8>, 0, this.phys.size) } + Ok(this) + } + + pub fn from_physbox(phys: PhysBox, value: T) -> Result<Self> { + let this = Self::from_physbox_uninit(phys)?; + + Ok(unsafe { + ptr::write(this.virt, MaybeUninit::new(value)); + this.assume_init() + }) + } + + pub fn new(value: T) -> Result<Self> { + let phys = PhysBox::new(mem::size_of::<T>())?; + Self::from_physbox(phys, value) + } + pub fn zeroed() -> Result<Dma<MaybeUninit<T>>> { + let phys = PhysBox::new(mem::size_of::<T>())?; + Self::from_physbox_zeroed(phys) + } +} + +impl<T> Dma<MaybeUninit<T>> { + pub unsafe fn assume_init(self) -> Dma<T> { + let &Dma { phys: PhysBox { address, size }, virt } = &self; + mem::forget(self); + + Dma { + phys: PhysBox { address, size }, + virt: virt as *mut T, + } + } +} +impl<T: ?Sized> Dma<T> { + pub fn physical(&self) -> usize { + self.phys.address() + } + pub fn size(&self) -> usize { + self.phys.size() + } + pub fn phys(&self) -> &PhysBox { + &self.phys + } +} + +impl<T> Dma<[T]> { + pub fn from_physbox_uninit_unsized(phys: PhysBox, len: usize) -> Result<Dma<[MaybeUninit<T>]>> { + let max_len = phys.size() / mem::size_of::<T>(); + assert!(len <= max_len); + + Ok(Dma { + virt: unsafe { slice::from_raw_parts_mut(crate::physmap(phys.address, phys.size, crate::PHYSMAP_WRITE)? as *mut MaybeUninit<T>, len) } as *mut [MaybeUninit<T>], + phys, + }) + } + pub fn from_physbox_zeroed_unsized(phys: PhysBox, len: usize) -> Result<Dma<[MaybeUninit<T>]>> { + let this = Self::from_physbox_uninit_unsized(phys, len)?; + unsafe { ptr::write_bytes(this.virt as *mut MaybeUninit<u8>, 0, this.phys.size()) } + Ok(this) + } + /// Creates a new DMA buffer with a size only known at runtime. + /// ## Safety + /// * `T` must be properly aligned. + /// * `T` must be valid as zeroed (i.e. no NonNull pointers). + pub unsafe fn zeroed_unsized(count: usize) -> Result<Self> { + let phys = PhysBox::new(mem::size_of::<T>() * count)?; + Ok(Self::from_physbox_zeroed_unsized(phys, count)?.assume_init()) + } +} +impl<T> Dma<[MaybeUninit<T>]> { + pub unsafe fn assume_init(self) -> Dma<[T]> { + let &Dma { phys: PhysBox { address, size }, virt } = &self; + mem::forget(self); + + Dma { + phys: PhysBox { address, size }, + virt: virt as *mut [T], + } + } +} + +impl<T: ?Sized> Deref for Dma<T> { + type Target = T; + fn deref(&self) -> &T { + unsafe { &*self.virt } + } +} + +impl<T: ?Sized> DerefMut for Dma<T> { + fn deref_mut(&mut self) -> &mut T { + unsafe { &mut *self.virt } + } +} + +impl<T: ?Sized> Drop for Dma<T> { + fn drop(&mut self) { + unsafe { ptr::drop_in_place(self.virt) } + let _ = unsafe { crate::physunmap(self.virt as *mut u8 as usize) }; + } +} |