mmu.c

/*
 * Copyright (c) 2006-2019, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author             Notes
 * 2020-02-20     bigmagic           first version
 */

#include <mmu.h>
#include <stddef.h>

#define TTBR_CNP    1

typedef unsigned long int	uint64_t;

static unsigned long main_tbl[512 * 20] __attribute__((aligned (4096)));

#define IS_ALIGNED(x, a)		(((x) & ((typeof(x))(a) - 1)) == 0)

//映射方式
#define PMD_TYPE_SECT		(1 << 0)

#define PMD_TYPE_TABLE		(3 << 0)

#define PTE_TYPE_PAGE		(3 << 0)

#define BITS_PER_VA                39

/* Granule size of 4KB is being used */
#define GRANULE_SIZE_SHIFT         12
#define GRANULE_SIZE               (1 << GRANULE_SIZE_SHIFT)
#define XLAT_ADDR_MASK             ((1UL << BITS_PER_VA) - GRANULE_SIZE)

#define PMD_TYPE_MASK		(3 << 0)

int free_idx = 1;

void mmu_memset(char *dst, char v,  size_t len)
{
    while (len--)
    {
        *dst++ = v;
    }
}

static unsigned long __page_off = 0;
static unsigned long get_free_page(void) {
    __page_off += 512;
    return (unsigned long)(main_tbl + __page_off);
}

void mmu_init(void)
{
    unsigned long val64;
    unsigned long val32; //val32不是uint32_t,val32只是表示相关的那个寄存器是32位的

    val64 = 0x007f6eUL;
    __asm__ volatile("msr MAIR_EL1, %0\n dsb sy\n"::"r"(val64));
    __asm__ volatile("mrs %0, MAIR_EL1\n dsb sy\n":"=r"(val64));

    //TCR_EL1
    val32 = (16UL << 0)//48 位
        | (0x0UL << 6)//没有用到
        | (0x0UL << 7)//使能enable lower half
        | (0x3UL << 8)//写回模式，没有cahce访问
        | (0x3UL << 10)//Inner Shareable
        | (0x2UL << 12)
        | (0x0UL << 14)//4K
        | (0x0UL << 16)
        | (0x0UL << 22)
        | (0x1UL << 23)
        | (0x2UL << 30)
        | (0x1UL << 32)
        | (0x0UL << 35)
        | (0x0UL << 36)
        | (0x0UL << 37)
        | (0x0UL << 38);
    __asm__ volatile("msr TCR_EL1, %0\n"::"r"(val32));
    __asm__ volatile("mrs %0, TCR_EL1\n":"=r"(val32));

    __asm__ volatile("msr TTBR0_EL1, %0\n dsb sy\n"::"r"(main_tbl));
    __asm__ volatile("mrs %0, TTBR0_EL1\n dsb sy\n":"=r"(val64));

    mmu_memset((char *)main_tbl, 0, 4096);
}

void mmu_enable(void)
{
    unsigned long val64;
    unsigned long val32;

    //关闭指令cache
    __asm__ volatile("mrs %0, SCTLR_EL1\n":"=r"(val64));
    val64 &= ~0x1000; //disable I
    __asm__ volatile("dmb sy\n msr SCTLR_EL1, %0\n isb sy\n"::"r"(val64));

    //清除指令cache
    __asm__ volatile("IC IALLUIS\n dsb sy\n isb sy\n");
    //清除tlb
    __asm__ volatile("tlbi vmalle1\n dsb sy\n isb sy\n");

    //SCTLR_EL1, turn on mmu
    __asm__ volatile("mrs %0, SCTLR_EL1\n":"=r"(val32));
    val32 |= 0x1005; //enable mmu, I C M
    __asm__ volatile("dmb sy\n msr SCTLR_EL1, %0\nisb sy\n"::"r"(val32));
}

static int map_single_page_2M(unsigned long* lv0_tbl, unsigned long va, unsigned long pa, unsigned long attr) {
    int level;
    unsigned long* cur_lv_tbl = lv0_tbl;
    unsigned long page;
    unsigned long off;
    int level_shift = 39;

    if (va & (0x200000UL - 1)) {
        return MMU_MAP_ERROR_VANOTALIGN;
    }
    if (pa & (0x200000UL - 1)) {
        return MMU_MAP_ERROR_PANOTALIGN;
    }
    for (level = 0; level < 2; level++) {
        off = (va >> level_shift);
        off &= MMU_LEVEL_MASK;
        if ((cur_lv_tbl[off] & 1) == 0) {
            page = get_free_page();
            if (!page) {
                return MMU_MAP_ERROR_NOPAGE;
            }
            mmu_memset((char *)page, 0, 4096);
            cur_lv_tbl[off] = page | 0x3UL;
        }
        page = cur_lv_tbl[off];
        if (!(page & 0x2)) {
            //is block! error!
            return MMU_MAP_ERROR_CONFLICT;
        }
        cur_lv_tbl = (unsigned long*)(page & 0x0000fffffffff000UL);
        level_shift -= 9;
    }
    attr &= 0xfff0000000000ffcUL;
    pa |= (attr | 0x1UL); //block
    off = (va >> 21);
    off &= MMU_LEVEL_MASK;
    cur_lv_tbl[off] = pa;
    return 0;
}

int armv8_map_2M(unsigned long va, unsigned long pa, int count, unsigned long attr)
{
    int i;
    int ret;

    if (va & (0x200000 - 1))
    {
        return -1;
    }
    if (pa & (0x200000 - 1))
    {
        return -1;
    }
    for (i = 0; i < count; i++)
    {
        ret = map_single_page_2M((unsigned long *)main_tbl, va, pa, attr);
        va += 0x200000;
        pa += 0x200000;
        if (ret != 0)
        {
            return ret;
        }
    }
    return 0;
}

//将表的地址映射到其他的地方去
static void set_table(uint64_t *pt, uint64_t *table_addr)
{
	uint64_t val;
    //0x607

	val = (0x3UL | (uint64_t)table_addr);//(0x3UL | (uint64_t)table_addr);
	*pt = val;
}

void mmu_memset2(unsigned char *dst, char v,  int len)
{
    while (len--)
    {
        *dst++ = v;
    }
}

static uint64_t *create_table(void)
{
	uint64_t *new_table = (uint64_t *)((unsigned char *)&main_tbl[0] + free_idx * 4096); //+ free_idx * GRANULE_SIZE;
	/* Mark all entries as invalid */
	mmu_memset2((unsigned char *)new_table, 0, 4096);
	free_idx++;
	return new_table;
}

static int pte_type(uint64_t *pte)
{
	return *pte & PMD_TYPE_MASK;
}

static int level2shift(int level)
{
	/* Page is 12 bits wide, every level translates 9 bits */
    //
	return (12 + 9 * (3 - level));
}


uint64_t *test_table = 0;



//根据表映射
static uint64_t *get_level_table(uint64_t *pte)
{
	uint64_t *table = (uint64_t *)(*pte & XLAT_ADDR_MASK);
	
	if (pte_type(pte) != PMD_TYPE_TABLE) {
		table = create_table();
		set_table(pte, table);
	}
	return table;
}


static void map_region(uint64_t virt, uint64_t phys, uint64_t size, uint64_t attr)
{
	uint64_t block_size = 0;
	uint64_t block_shift = 0;
	uint64_t *pte;
	uint64_t idx = 0;
	uint64_t addr = 0;
	uint64_t *table = 0;
	int level = 0;

	addr = virt;
	while (size) {
		table = &main_tbl[0];//将一级页表的地址赋值
		for (level = 0; level < 4; level++) {
			block_shift = level2shift(level);
            idx = addr >> block_shift;
			idx = idx%512;
            block_size = (uint64_t)(1L << block_shift);
			pte = table + idx;

			if (size >= block_size && IS_ALIGNED(addr, block_size)) {
                attr &= 0xfff0000000000ffcUL;
                if(level != 3)
                {
                    *pte = phys | (attr | 0x1UL);
                }
                else
                {
                    *pte = phys | (attr | 0x3UL);
                }
				addr += block_size;
				phys += block_size;
				size -= block_size;
				break;
			}
			table = get_level_table(pte);
		}
	}
}

void armv8_map(unsigned long va, unsigned long pa, unsigned long size, unsigned long attr)
{
    map_region(va, pa, size, attr);
}