zynq-rs/libcortex_a9/src/uncached.rs

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2020-06-15 05:50:39 +08:00
use core::{
ops::{Deref, DerefMut},
mem::{align_of, size_of},
};
use alloc::alloc::{alloc_zeroed, dealloc, Layout, LayoutErr};
use crate::mmu::{L1_PAGE_SIZE, L1Table};
pub struct Uncached<'t, T: 't> {
layout: Layout,
data: &'t mut T,
}
impl<'t, T: 't> Uncached<'t, T> {
/// allocates in chunks of 1 MB
pub fn alloc(src: T) -> Result<Self, LayoutErr> {
// round to full pages
let size = (size_of::<T>() | (L1_PAGE_SIZE - 1)) + 1;
let align = align_of::<T>()
.max(L1_PAGE_SIZE);
let layout = Layout::from_size_align(size, align)?;
let ptr = unsafe { alloc::alloc::alloc(layout).cast::<T>() };
assert_eq!((ptr as usize) & (L1_PAGE_SIZE - 1), 0);
let start = ptr as usize;
for page_start in (start..(start + size)).step_by(L1_PAGE_SIZE) {
L1Table::get()
.update(page_start as *const (), |l1_section| {
l1_section.cacheable = false;
l1_section.bufferable = false;
});
}
// initialize
unsafe {
core::ptr::write(ptr, src);
}
let data = unsafe { &mut *ptr };
Ok(Uncached { layout, data })
}
}
impl<'t, T: 't> Drop for Uncached<'t, T> {
fn drop(&mut self) {
unsafe {
dealloc(self.data as *mut _ as *mut u8, self.layout);
}
}
}
impl<'t, T: 't> Deref for Uncached<'t, T> {
type Target = T;
fn deref(&self) -> &Self::Target {
self.data
}
}
impl<'t, T: 't> DerefMut for Uncached<'t, T> {
fn deref_mut(&mut self) -> &mut Self::Target {
self.data
}
}