begin MMU implementation

src/cortex_a9/mmu.rs

@@ -0,0 +1,378 @@
+use core::mem::uninitialized;
+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 {
+        /// Must be aligned to 1 MB
+        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
+    }
+}
+
+const L1TABLE_SIZE: usize = 4096;
+
+#[repr(C, align(16384))]
+pub struct L1Table {
+    table: [L1Entry; L1TABLE_SIZE]
+}
+
+impl L1Table {
+    pub fn flat_layout() -> Self {
+        let mut result = L1Table {
+            table: unsafe { uninitialized() }
+        };
+        /* 0x00000000 - 0x00100000 (cacheable) */
+        result.direct_mapped_section(0, L1Section {
+            global: true,
+            shareable: true,
+            access: AccessPermissions::FullAccess,
+            tex: 0b101,
+            domain: 0b1111,
+            exec: true,
+            cacheable: false,
+            bufferable: true,
+        });
+        /* (DDR cacheable) */
+        for ddr in 1..=0x1ff {
+            result.direct_mapped_section(ddr, L1Section {
+                global: true,
+                shareable: true,
+                access: AccessPermissions::FullAccess,
+                tex: 0b101,
+                domain: 0b1111,
+                exec: true,
+                cacheable: true,
+                bufferable: true,
+            });
+        }
+        /* (unassigned/reserved). */
+        for undef in 0x1ff..=0x3ff {
+            result.direct_mapped_section(undef, L1Section {
+                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 {
+            result.direct_mapped_section(fpga_slave, L1Section {
+                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 {
+            result.direct_mapped_section(fpga_slave, L1Section {
+                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 {
+            result.direct_mapped_section(undef, L1Section {
+                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 {
+            result.direct_mapped_section(mmapped_dev, L1Section {
+                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 {
+            result.direct_mapped_section(undef, L1Section {
+                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 {
+            result.direct_mapped_section(nand, L1Section {
+                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 {
+            result.direct_mapped_section(nor, L1Section {
+                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 {
+            result.direct_mapped_section(nor, L1Section {
+                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 {
+            result.direct_mapped_section(undef, L1Section {
+                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 {
+            result.direct_mapped_section(apb, L1Section {
+                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 {
+            result.direct_mapped_section(undef, L1Section {
+                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 {
+            result.direct_mapped_section(qspi, L1Section {
+                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 {
+            result.direct_mapped_section(undef, L1Section {
+                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) */
+        result.direct_mapped_section(0xfff, L1Section {
+            global: true,
+            shareable: false,
+            access: AccessPermissions::FullAccess,
+            tex: 0b100,
+            domain: 0,
+            exec: true,
+            cacheable: true,
+            bufferable: true,
+        });
+
+        result
+    }
+
+    #[inline(always)]
+    fn direct_mapped_section(&mut self, index: usize, section: L1Section) {
+        assert!(index < L1TABLE_SIZE);
+
+        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)
+    );
+    
+    // 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();
+
+    // table must live until here
+    drop(l1table.table);
+    unreachable!();
+}

src/cortex_a9/mod.rs

@@ -1,4 +1,5 @@
 pub mod asm;
 pub mod regs;
+pub mod mmu;
 
 global_asm!(include_str!("exceptions.s"));

src/cortex_a9/regs.rs

@@ -1,4 +1,4 @@
-use crate::register_bit;
+use crate::{register_bit, register_bits};
 use crate::regs::{RegisterR, RegisterW, RegisterRW};
 
 macro_rules! def_reg_r {
@@ -115,6 +115,28 @@ register_bit!(sctlr,
               /// Thumb Exception Enable
               te, 30);
 
+/// Domain Access Control Register
+pub struct DACR;
+def_reg_r!(DACR, u32, "mrc p15, 0, $0, c3, c0, 0");
+def_reg_w!(DACR, u32, "mcr p15, 0, $0, c3, c0, 0");
+
+/// Translation Table Base Register 0
+pub struct TTBR0;
+/// Translation Table Base Register 1
+pub struct TTBR1;
+def_reg_r!(TTBR0, ttbr::Read, "mrc p15, 0, $0, c2, c0, 0");
+def_reg_w!(TTBR0, ttbr::Write, "mcr p15, 0, $0, c2, c0, 0");
+def_reg_r!(TTBR1, ttbr::Read, "mrc p15, 0, $0, c2, c0, 1");
+def_reg_w!(TTBR1, ttbr::Write, "mcr p15, 0, $0, c2, c0, 1");
+wrap_reg!(ttbr);
+register_bits!(ttbr, table_base, u32, 14, 31);
+register_bit!(ttbr, irgn0, 6);
+register_bits!(ttbr, rgn, u8, 3, 4);
+register_bit!(ttbr,
+              /// Translation table walk to shared memory?
+              s, 1);
+register_bit!(ttbr, irgn1, 0);
+
 /// Invalidate TLBs
 #[inline(always)]
 pub fn tlbiall() {

src/main.rs

@@ -4,6 +4,7 @@
 #![feature(global_asm)]
 #![feature(naked_functions)]
 #![feature(compiler_builtins_lib)]
+#![feature(never_type)]
 
 use core::fmt::Write;
 use core::mem::uninitialized;
@@ -19,7 +20,7 @@ use uart::Uart;
 mod eth;
 
 use crate::regs::{RegisterR, RegisterW};
-use crate::cortex_a9::{asm, regs::*};
+use crate::cortex_a9::{asm, regs::*, mmu};
 
 extern "C" {
     static mut __bss_start: u32;
@@ -51,8 +52,10 @@ unsafe fn boot_core0() -> ! {
     l1_cache_init();
     zero_bss(&mut __bss_start, &mut __bss_end);
 
-    main();
+    mmu::with_mmu(&mmu::L1Table::flat_layout(), || {
-    panic!("return from main");
+        main();
+        panic!("return from main");
+    });
 }
 
 fn l1_cache_init() {
@@ -64,24 +67,6 @@ fn l1_cache_init() {
     bpiall();
     // Invalidate D-Cache
     dccisw();
-
-    // (Initialize MMU)
-
-    // Enable I-Cache and D-Cache
-    SCTLR.write(
-        SCTLR::zeroed()
-            .m(false)
-            .a(false)
-            .c(true)
-            .i(true)
-            .unaligned(true)
-    );
-
-    // Synchronization barriers
-    // Allows MMU to start
-    asm::dsb();
-    // Flushes pre-fetch buffer
-    asm::isb();
 }
 
 const UART_RATE: u32 = 115_200;