zc706/src/cortex_a9/mmu.rs

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use bit_field::BitField;
use super::{regs::*, asm};
use crate::regs::RegisterW;
#[derive(Copy, Clone)]
#[repr(u8)]
pub enum AccessDomain {
NoAccess = 0b00,
Client = 0b01,
_Reserved = 0b10,
Manager = 0b11,
}
const ACCESS_DOMAINS_SIZE: usize = 16;
pub struct AccessDomains([AccessDomain; ACCESS_DOMAINS_SIZE]);
impl AccessDomains {
pub fn all_manager() -> Self {
AccessDomains([AccessDomain::Manager; ACCESS_DOMAINS_SIZE])
}
}
impl Into<u32> for AccessDomains {
fn into(self) -> u32 {
let mut result = 0;
for (i, domain) in self.0.iter().enumerate() {
result |= (*domain as u32) << (2 * i);
}
result
}
}
#[derive(Copy, Clone)]
#[repr(u8)]
pub enum AccessPermissions {
PermissionFault = 0,
PrivilegedOnly,
NoUserWrite,
FullAccess,
_Reserved1,
PrivilegedReadOnly,
ReadOnly,
_Reserved2
}
impl AccessPermissions {
fn ap(&self) -> u8 {
(*self as u8) & 0b11
}
fn apx(&self) -> bool {
(*self as u8) > (AccessPermissions::FullAccess as u8)
}
}
pub struct L1Section {
pub global: bool,
pub shareable: bool,
pub access: AccessPermissions,
/// Type EXtension
pub tex: u8,
pub domain: u8,
pub exec: bool,
pub cacheable: bool,
pub bufferable: bool,
}
#[repr(C)]
#[derive(Clone, Copy)]
pub struct L1Entry(u32);
impl L1Entry {
#[inline(always)]
pub fn section(phys_base: u32, section: L1Section) -> Self {
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// Must be aligned to 1 MB
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assert!(phys_base & 0x000f_ffff == 0);
let mut entry = L1Entry(phys_base);
entry.0.set_bits(0..=1, 0b10);
entry.0.set_bit(2, section.bufferable);
entry.0.set_bit(3, section.cacheable);
entry.0.set_bit(4, !section.exec);
assert!(section.domain < 16);
entry.0.set_bits(5..=8, section.domain.into());
entry.0.set_bits(10..=11, section.access.ap().into());
assert!(section.tex < 8);
entry.0.set_bits(12..=14, section.tex.into());
entry.0.set_bit(15, section.access.apx());
entry.0.set_bit(16, section.shareable);
entry.0.set_bit(17, !section.global);
entry
}
}
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const L1_TABLE_SIZE: usize = 4096;
#[doc(hidden)]
#[link_section = ".bss.l1_table"]
#[no_mangle]
pub static mut l1_table: L1Table = L1Table {
table: [L1Entry(0); L1_TABLE_SIZE]
};
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/// The `#[repr(align(16384))]` is unfortunately ineffective. Hence we
/// require explicit linking to a region defined in the linker script.
#[repr(align(16384))]
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pub struct L1Table {
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table: [L1Entry; L1_TABLE_SIZE]
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}
impl L1Table {
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pub fn get() -> &'static mut Self {
unsafe {
&mut l1_table
}
}
pub fn setup_flat_layout(&mut self) -> &Self {
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/* 0x00000000 - 0x00100000 (cacheable) */
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self.direct_mapped_section(0, L1Section {
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global: true,
shareable: true,
access: AccessPermissions::FullAccess,
tex: 0b101,
domain: 0b1111,
exec: true,
cacheable: true,
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bufferable: true,
});
/* (DDR cacheable) */
for ddr in 1..=0x1ff {
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self.direct_mapped_section(ddr, L1Section {
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global: true,
shareable: true,
access: AccessPermissions::FullAccess,
tex: 0b101,
domain: 0b1111,
exec: true,
cacheable: true,
bufferable: true,
});
}
/* (unassigned/reserved). */
for undef in 0x1ff..=0x3ff {
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self.direct_mapped_section(undef, L1Section {
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global: false,
shareable: false,
access: AccessPermissions::PermissionFault,
tex: 0,
domain: 0,
exec: false,
cacheable: false,
bufferable: false,
});
}
/* 0x40000000 - 0x7fffffff (FPGA slave0) */
for fpga_slave in 0x400..=0x7ff {
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self.direct_mapped_section(fpga_slave, L1Section {
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global: true,
shareable: false,
access: AccessPermissions::FullAccess,
tex: 0,
domain: 0,
exec: false,
cacheable: false,
bufferable: false,
});
}
/* 0x80000000 - 0xbfffffff (FPGA slave1) */
for fpga_slave in 0x800..=0xbff {
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self.direct_mapped_section(fpga_slave, L1Section {
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global: true,
shareable: false,
access: AccessPermissions::FullAccess,
tex: 0,
domain: 0,
exec: false,
cacheable: false,
bufferable: false,
});
}
/* 0xc0000000 - 0xdfffffff (unassigned/reserved). */
for undef in 0xc00..=0xdff {
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self.direct_mapped_section(undef, L1Section {
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global: false,
shareable: false,
access: AccessPermissions::PermissionFault,
tex: 0,
domain: 0,
exec: false,
cacheable: false,
bufferable: false,
});
}
/* 0xe0000000 - 0xe02fffff (Memory mapped devices)
* UART/USB/IIC/SPI/CAN/GEM/GPIO/QSPI/SD/NAND */
for mmapped_dev in 0xe00..=0xe02 {
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self.direct_mapped_section(mmapped_dev, L1Section {
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global: true,
shareable: false,
access: AccessPermissions::FullAccess,
tex: 0,
domain: 0,
exec: true,
cacheable: false,
bufferable: true,
});
}
/* 0xe0300000 - 0xe0ffffff (unassigned/reserved). */
for undef in 0xe03..=0xe0f {
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self.direct_mapped_section(undef, L1Section {
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global: false,
shareable: false,
access: AccessPermissions::PermissionFault,
tex: 0,
domain: 0,
exec: false,
cacheable: false,
bufferable: false,
});
}
/* 0xe1000000 - 0xe1ffffff (NAND) */
for nand in 0xe10..=0xe1f {
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self.direct_mapped_section(nand, L1Section {
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global: true,
shareable: false,
access: AccessPermissions::FullAccess,
tex: 0,
domain: 0,
exec: true,
cacheable: false,
bufferable: true,
});
}
/* 0xe2000000 - 0xe3ffffff (NOR) */
for nor in 0xe20..=0xe3f {
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self.direct_mapped_section(nor, L1Section {
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global: true,
shareable: false,
access: AccessPermissions::FullAccess,
tex: 0,
domain: 0,
exec: true,
cacheable: false,
bufferable: true,
});
}
/* 0xe4000000 - 0xe5ffffff (SRAM) */
for nor in 0xe40..=0xe5f {
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self.direct_mapped_section(nor, L1Section {
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global: true,
shareable: false,
access: AccessPermissions::FullAccess,
tex: 0,
domain: 0,
exec: true,
cacheable: true,
bufferable: true,
});
}
/* 0xe6000000 - 0xf7ffffff (unassigned/reserved). */
for undef in 0xe60..=0xf7f {
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self.direct_mapped_section(undef, L1Section {
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global: false,
shareable: false,
access: AccessPermissions::PermissionFault,
tex: 0,
domain: 0,
exec: false,
cacheable: false,
bufferable: false,
});
}
/* 0xf8000000 - 0xf8ffffff (AMBA APB Peripherals) */
for apb in 0xf80..=0xf8f {
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self.direct_mapped_section(apb, L1Section {
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global: true,
shareable: false,
access: AccessPermissions::FullAccess,
tex: 0,
domain: 0,
exec: true,
cacheable: false,
bufferable: true,
});
}
/* 0xf9000000 - 0xfbffffff (unassigned/reserved). */
for undef in 0xf90..=0xfbf {
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self.direct_mapped_section(undef, L1Section {
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global: false,
shareable: false,
access: AccessPermissions::PermissionFault,
tex: 0,
domain: 0,
exec: false,
cacheable: false,
bufferable: false,
});
}
/* 0xfc000000 - 0xfdffffff (Linear QSPI - XIP) */
for qspi in 0xfc0..=0xfdf {
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self.direct_mapped_section(qspi, L1Section {
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global: true,
shareable: false,
access: AccessPermissions::FullAccess,
tex: 0,
domain: 0,
exec: true,
cacheable: false,
bufferable: true,
});
}
/* 0xfe000000 - 0xffefffff (unassigned/reserved). */
for undef in 0xfe0..=0xffe {
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self.direct_mapped_section(undef, L1Section {
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global: false,
shareable: false,
access: AccessPermissions::PermissionFault,
tex: 0,
domain: 0,
exec: false,
cacheable: false,
bufferable: false,
});
}
/* 0xfff00000 - 0xffffffff (256K OCM when mapped to high address space) */
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self.direct_mapped_section(0xfff, L1Section {
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global: true,
shareable: false,
access: AccessPermissions::FullAccess,
tex: 0b100,
domain: 0,
exec: true,
cacheable: true,
bufferable: true,
});
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self
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}
#[inline(always)]
fn direct_mapped_section(&mut self, index: usize, section: L1Section) {
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assert!(index < L1_TABLE_SIZE);
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let base = (index as u32) << 20;
self.table[index] = L1Entry::section(base, section);
}
}
pub fn with_mmu<F: FnMut() -> !>(l1table: &L1Table, mut f: F) -> ! {
let domains = AccessDomains::all_manager();
DACR.write(domains.into());
let table_base = &l1table.table as *const _ as u32;
assert!(table_base & 0x3fff == 0);
TTBR0.write(
TTBR0::zeroed()
.irgn1(true)
.s(true)
// Outer Cacheable Write-Back, no allocate on write.
.rgn(0b11)
.irgn0(true)
.table_base(table_base >> 14)
);
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// Enable I-Cache and D-Cache
SCTLR.write(
SCTLR::zeroed()
.m(true)
.a(false)
.c(true)
.i(true)
.unaligned(true)
);
// Synchronization barriers
// Allows MMU to start
asm::dsb();
// Flushes pre-fetch buffer
asm::isb();
f();
}