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.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) create mode 100644 src/lib/mmu.c (limited to 'src/lib/mmu.c') 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