From 9169796632fcdeb5e8e74ed60c6cbe31081e51f2 Mon Sep 17 00:00:00 2001 From: Christian Cunningham Date: Thu, 24 Feb 2022 23:38:38 -0700 Subject: MMU and working on hardware --- src/lib/mmu.S | 45 +++++++++++++++++++++++++++++++++++++++++++++ src/lib/mmu.c | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 77 insertions(+) create mode 100644 src/lib/mmu.S create mode 100644 src/lib/mmu.c (limited to 'src/lib') diff --git a/src/lib/mmu.S b/src/lib/mmu.S new file mode 100644 index 0000000..faca3cc --- /dev/null +++ b/src/lib/mmu.S @@ -0,0 +1,45 @@ +.section .text +.globl mmu_start +mmu_start: + mov r2, #0 + // Invalidate Caches + mcr p15,0,r2,c7,c1,6 + // Invalidate TLB entries + mcr p15,0,r2,c8,c7,0 + // Data synchronisation barrier + mcr p15,0,r2,c7,c10,4 + + // Set all domains to 0b11 + mvn r2, #0 + bic r2, #0xC + mcr p15,0,r2,c3,c0,0 + + // Set the translation table base address (remember to align 16 KiB!) + mcr p15,0,r0,c2,c0,0 + mcr p15,0,r0,c2,c0,1 + mov r3, #0 + mcr p15,0,r3,c2,c0,2 + + // Set the bits mentioned above + mrc p15,0,r2,c1,c0,0 + orr r2,r2,r1 + mcr p15,0,r2,c1,c0,0 + bx lr + +.globl mmu_stop +mmu_stop: + mrc p15,0,r2,c1,c0,0 + bic r2,#0x1000 + bic r2,#0x0004 + bic r2,#0x0001 + mcr p15,0,r2,c1,c0,0 + bx lr + +.globl tlb_invalidate +tlb_invalidate: + mov r2, #0 + // Invalidate Entries + mcr p15, 0, r2, c8, c7, 0 + // DSB + mcr p15, 0, r2, c7, c10, 4 + bx lr diff --git a/src/lib/mmu.c b/src/lib/mmu.c new file mode 100644 index 0000000..6a947c5 --- /dev/null +++ b/src/lib/mmu.c @@ -0,0 +1,32 @@ +#include + +#define CACHABLE 0x08 +#define BUFFERABLE 0x04 +#define NO_PERMISSIONS_REQUIRED 0b11 << 10 +#define MMU_TABLE_BASE 0x00004000 + +void mmu_start(unsigned long base, unsigned long flags); + +void mmu_section(unsigned long virtual, unsigned long physical, unsigned long flags) +{ + unsigned long offset = virtual >> 20; + unsigned long* entry = (unsigned long*)(MMU_TABLE_BASE | (offset << 2)); + unsigned long physval = (physical & 0xFFF00000) | (flags & 0x7FFC) | 0x00C02; + *entry = physval; +} + +void mmu_init(void) +{ + mmu_section(0x00000000, 0x00000000, CACHABLE | BUFFERABLE); + for (unsigned long addr = 0x00100000;; addr += 0x00100000) { + mmu_section(addr, addr, NO_PERMISSIONS_REQUIRED); + if (addr == 0x02000000) + mmu_section(addr, addr, CACHABLE | BUFFERABLE | NO_PERMISSIONS_REQUIRED); + //else if (addr == 0x3F000000) + //else + // mmu_section(addr, addr, NO_PERMISSIONS_REQUIRED); + if (addr == 0xFFF00000) + break; + } + mmu_start(MMU_TABLE_BASE,0x00000001|0x1000|0x0004); +} -- cgit v1.2.1