// SPDX-License-Identifier: GPL-2.0
/*
 * linux/arch/m68k/mm/motorola.c
 *
 * Routines specific to the Motorola MMU, originally from:
 * linux/arch/m68k/init.c
 * which are Copyright (C) 1995 Hamish Macdonald
 *
 * Moved 8/20/1999 Sam Creasey
 */

#include <linux/module.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/memblock.h>
#include <linux/gfp.h>

#include <asm/setup.h>
#include <linux/uaccess.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/machdep.h>
#include <asm/io.h>
#include <asm/dma.h>
#ifdef CONFIG_ATARI
#include <asm/atari_stram.h>
#endif
#include <asm/sections.h>

#undef DEBUG

#ifndef mm_cachebits
/*
 * Bits to add to page descriptors for "normal" caching mode.
 * For 68020/030 this is 0.
 * For 68040, this is _PAGE_CACHE040 (cachable, copyback)
 */
unsigned long mm_cachebits;
EXPORT_SYMBOL(mm_cachebits);
#endif

/* Prior to calling these routines, the page should have been flushed
 * from both the cache and ATC, or the CPU might not notice that the
 * cache setting for the page has been changed. -jskov
 */
static inline void nocache_page(void *vaddr)
{
        unsigned long addr = (unsigned long)vaddr;

        if (CPU_IS_040_OR_060) {
                pte_t *ptep = virt_to_kpte(addr);

                *ptep = pte_mknocache(*ptep);
        }
}

static inline void cache_page(void *vaddr)
{
        unsigned long addr = (unsigned long)vaddr;

        if (CPU_IS_040_OR_060) {
                pte_t *ptep = virt_to_kpte(addr);

                *ptep = pte_mkcache(*ptep);
        }
}

/*
 * Motorola 680x0 user's manual recommends using uncached memory for address
 * translation tables.
 *
 * Seeing how the MMU can be external on (some of) these chips, that seems like
 * a very important recommendation to follow. Provide some helpers to combat
 * 'variation' amongst the users of this.
 */

void mmu_page_ctor(void *page)
{
        __flush_page_to_ram(page);
        flush_tlb_kernel_page(page);
        nocache_page(page);
}

void mmu_page_dtor(void *page)
{
        cache_page(page);
}

/* ++andreas: {get,free}_pointer_table rewritten to use unused fields from
   struct page instead of separately kmalloced struct.  Stolen from
   arch/sparc/mm/srmmu.c ... */

typedef struct list_head ptable_desc;

static struct list_head ptable_list[2] = {
        LIST_HEAD_INIT(ptable_list[0]),
        LIST_HEAD_INIT(ptable_list[1]),
};

#define PD_PTABLE(page) ((ptable_desc *)&(virt_to_page(page)->lru))
#define PD_PAGE(ptable) (list_entry(ptable, struct page, lru))
#define PD_MARKBITS(dp) (*(unsigned int *)&PD_PAGE(dp)->index)

static const int ptable_shift[2] = {
        7+2, /* PGD, PMD */
        6+2, /* PTE */
};

#define ptable_size(type) (1U << ptable_shift[type])
#define ptable_mask(type) ((1U << (PAGE_SIZE / ptable_size(type))) - 1)

void __init init_pointer_table(void *table, int type)
{
        ptable_desc *dp;
        unsigned long ptable = (unsigned long)table;
        unsigned long page = ptable & PAGE_MASK;
        unsigned int mask = 1U << ((ptable - page)/ptable_size(type));

        dp = PD_PTABLE(page);
        if (!(PD_MARKBITS(dp) & mask)) {
                PD_MARKBITS(dp) = ptable_mask(type);
                list_add(dp, &ptable_list[type]);
        }

        PD_MARKBITS(dp) &= ~mask;
        pr_debug("init_pointer_table: %lx, %x\n", ptable, PD_MARKBITS(dp));

        /* unreserve the page so it's possible to free that page */
        __ClearPageReserved(PD_PAGE(dp));
        init_page_count(PD_PAGE(dp));

        return;
}

void *get_pointer_table(int type)
{
        ptable_desc *dp = ptable_list[type].next;
        unsigned int mask = list_empty(&ptable_list[type]) ? 0 : PD_MARKBITS(dp);
        unsigned int tmp, off;

        /*
         * For a pointer table for a user process address space, a
         * table is taken from a page allocated for the purpose.  Each
         * page can hold 8 pointer tables.  The page is remapped in
         * virtual address space to be noncacheable.
         */
        if (mask == 0) {
                void *page;
                ptable_desc *new;

                if (!(page = (void *)get_zeroed_page(GFP_KERNEL)))
                        return NULL;

                if (type == TABLE_PTE) {
                        /*
                         * m68k doesn't have SPLIT_PTE_PTLOCKS for not having
                         * SMP.
                         */
                        pgtable_pte_page_ctor(virt_to_page(page));
                }

                mmu_page_ctor(page);

                new = PD_PTABLE(page);
                PD_MARKBITS(new) = ptable_mask(type) - 1;
                list_add_tail(new, dp);

                return (pmd_t *)page;
        }

        for (tmp = 1, off = 0; (mask & tmp) == 0; tmp <<= 1, off += ptable_size(type))
                ;
        PD_MARKBITS(dp) = mask & ~tmp;
        if (!PD_MARKBITS(dp)) {
                /* move to end of list */
                list_move_tail(dp, &ptable_list[type]);
        }
        return page_address(PD_PAGE(dp)) + off;
}

int free_pointer_table(void *table, int type)
{
        ptable_desc *dp;
        unsigned long ptable = (unsigned long)table;
        unsigned long page = ptable & PAGE_MASK;
        unsigned int mask = 1U << ((ptable - page)/ptable_size(type));

        dp = PD_PTABLE(page);
        if (PD_MARKBITS (dp) & mask)
                panic ("table already free!");

        PD_MARKBITS (dp) |= mask;

        if (PD_MARKBITS(dp) == ptable_mask(type)) {
                /* all tables in page are free, free page */
                list_del(dp);
                mmu_page_dtor((void *)page);
                if (type == TABLE_PTE)
                        pgtable_pte_page_dtor(virt_to_page(page));
                free_page (page);
                return 1;
        } else if (ptable_list[type].next != dp) {
                /*
                 * move this descriptor to the front of the list, since
                 * it has one or more free tables.
                 */
                list_move(dp, &ptable_list[type]);
        }
        return 0;
}

/* size of memory already mapped in head.S */
extern __initdata unsigned long m68k_init_mapped_size;

extern unsigned long availmem;

static pte_t *last_pte_table __initdata = NULL;

static pte_t * __init kernel_page_table(void)
{
        pte_t *pte_table = last_pte_table;

        if (PAGE_ALIGNED(last_pte_table)) {
                pte_table = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
                if (!pte_table) {
                        panic("%s: Failed to allocate %lu bytes align=%lx\n",
                                        __func__, PAGE_SIZE, PAGE_SIZE);
                }

                clear_page(pte_table);
                mmu_page_ctor(pte_table);

                last_pte_table = pte_table;
        }

        last_pte_table += PTRS_PER_PTE;

        return pte_table;
}

static pmd_t *last_pmd_table __initdata = NULL;

static pmd_t * __init kernel_ptr_table(void)
{
        if (!last_pmd_table) {
                unsigned long pmd, last;
                int i;

                /* Find the last ptr table that was used in head.S and
                 * reuse the remaining space in that page for further
                 * ptr tables.
                 */
                last = (unsigned long)kernel_pg_dir;
                for (i = 0; i < PTRS_PER_PGD; i++) {
                        pud_t *pud = (pud_t *)(&kernel_pg_dir[i]);

                        if (!pud_present(*pud))
                                continue;
                        pmd = pgd_page_vaddr(kernel_pg_dir[i]);
                        if (pmd > last)
                                last = pmd;
                }

                last_pmd_table = (pmd_t *)last;
#ifdef DEBUG
                printk("kernel_ptr_init: %p\n", last_pmd_table);
#endif
        }

        last_pmd_table += PTRS_PER_PMD;
        if (PAGE_ALIGNED(last_pmd_table)) {
                last_pmd_table = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
                if (!last_pmd_table)
                        panic("%s: Failed to allocate %lu bytes align=%lx\n",
                              __func__, PAGE_SIZE, PAGE_SIZE);

                clear_page(last_pmd_table);
                mmu_page_ctor(last_pmd_table);
        }

        return last_pmd_table;
}

static void __init map_node(int node)
{
        unsigned long physaddr, virtaddr, size;
        pgd_t *pgd_dir;
        p4d_t *p4d_dir;
        pud_t *pud_dir;
        pmd_t *pmd_dir;
        pte_t *pte_dir;

        size = m68k_memory[node].size;
        physaddr = m68k_memory[node].addr;
        virtaddr = (unsigned long)phys_to_virt(physaddr);
        physaddr |= m68k_supervisor_cachemode |
                    _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_DIRTY;
        if (CPU_IS_040_OR_060)
                physaddr |= _PAGE_GLOBAL040;

        while (size > 0) {
#ifdef DEBUG
                if (!(virtaddr & (PMD_SIZE-1)))
                        printk ("\npa=%#lx va=%#lx ", physaddr & PAGE_MASK,
                                virtaddr);
#endif
                pgd_dir = pgd_offset_k(virtaddr);
                if (virtaddr && CPU_IS_020_OR_030) {
                        if (!(virtaddr & (PGDIR_SIZE-1)) &&
                            size >= PGDIR_SIZE) {
#ifdef DEBUG
                                printk ("[very early term]");
#endif
                                pgd_val(*pgd_dir) = physaddr;
                                size -= PGDIR_SIZE;
                                virtaddr += PGDIR_SIZE;
                                physaddr += PGDIR_SIZE;
                                continue;
                        }
                }
                p4d_dir = p4d_offset(pgd_dir, virtaddr);
                pud_dir = pud_offset(p4d_dir, virtaddr);
                if (!pud_present(*pud_dir)) {
                        pmd_dir = kernel_ptr_table();
#ifdef DEBUG
                        printk ("[new pointer %p]", pmd_dir);
#endif
                        pud_set(pud_dir, pmd_dir);
                } else
                        pmd_dir = pmd_offset(pud_dir, virtaddr);

                if (CPU_IS_020_OR_030) {
                        if (virtaddr) {
#ifdef DEBUG
                                printk ("[early term]");
#endif
                                pmd_val(*pmd_dir) = physaddr;
                                physaddr += PMD_SIZE;
                        } else {
                                int i;
#ifdef DEBUG
                                printk ("[zero map]");
#endif
                                pte_dir = kernel_page_table();
                                pmd_set(pmd_dir, pte_dir);

                                pte_val(*pte_dir++) = 0;
                                physaddr += PAGE_SIZE;
                                for (i = 1; i < PTRS_PER_PTE; physaddr += PAGE_SIZE, i++)
                                        pte_val(*pte_dir++) = physaddr;
                        }
                        size -= PMD_SIZE;
                        virtaddr += PMD_SIZE;
                } else {
                        if (!pmd_present(*pmd_dir)) {
#ifdef DEBUG
                                printk ("[new table]");
#endif
                                pte_dir = kernel_page_table();
                                pmd_set(pmd_dir, pte_dir);
                        }
                        pte_dir = pte_offset_kernel(pmd_dir, virtaddr);

                        if (virtaddr) {
                                if (!pte_present(*pte_dir))
                                        pte_val(*pte_dir) = physaddr;
                        } else
                                pte_val(*pte_dir) = 0;
                        size -= PAGE_SIZE;
                        virtaddr += PAGE_SIZE;
                        physaddr += PAGE_SIZE;
                }

        }
#ifdef DEBUG
        printk("\n");
#endif
}

/*
 * paging_init() continues the virtual memory environment setup which
 * was begun by the code in arch/head.S.
 */
void __init paging_init(void)
{
        unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
        unsigned long min_addr, max_addr;
        unsigned long addr;
        int i;

#ifdef DEBUG
        printk ("start of paging_init (%p, %lx)\n", kernel_pg_dir, availmem);
#endif

        /* Fix the cache mode in the page descriptors for the 680[46]0.  */
        if (CPU_IS_040_OR_060) {
                int i;
#ifndef mm_cachebits
                mm_cachebits = _PAGE_CACHE040;
#endif
                for (i = 0; i < 16; i++)
                        pgprot_val(protection_map[i]) |= _PAGE_CACHE040;
        }

        min_addr = m68k_memory[0].addr;
        max_addr = min_addr + m68k_memory[0].size;
        memblock_add_node(m68k_memory[0].addr, m68k_memory[0].size, 0);
        for (i = 1; i < m68k_num_memory;) {
                if (m68k_memory[i].addr < min_addr) {
                        printk("Ignoring memory chunk at 0x%lx:0x%lx before the first chunk\n",
                                m68k_memory[i].addr, m68k_memory[i].size);
                        printk("Fix your bootloader or use a memfile to make use of this area!\n");
                        m68k_num_memory--;
                        memmove(m68k_memory + i, m68k_memory + i + 1,
                                (m68k_num_memory - i) * sizeof(struct m68k_mem_info));
                        continue;
                }
                memblock_add_node(m68k_memory[i].addr, m68k_memory[i].size, i);
                addr = m68k_memory[i].addr + m68k_memory[i].size;
                if (addr > max_addr)
                        max_addr = addr;
                i++;
        }
        m68k_memoffset = min_addr - PAGE_OFFSET;
        m68k_virt_to_node_shift = fls(max_addr - min_addr - 1) - 6;

        module_fixup(NULL, __start_fixup, __stop_fixup);
        flush_icache();

        high_memory = phys_to_virt(max_addr);

        min_low_pfn = availmem >> PAGE_SHIFT;
        max_pfn = max_low_pfn = max_addr >> PAGE_SHIFT;

        /* Reserve kernel text/data/bss and the memory allocated in head.S */
        memblock_reserve(m68k_memory[0].addr, availmem - m68k_memory[0].addr);

        /*
         * Map the physical memory available into the kernel virtual
         * address space. Make sure memblock will not try to allocate
         * pages beyond the memory we already mapped in head.S
         */
        memblock_set_bottom_up(true);

        for (i = 0; i < m68k_num_memory; i++) {
                m68k_setup_node(i);
                map_node(i);
        }

        flush_tlb_all();

        /*
         * initialize the bad page table and bad page to point
         * to a couple of allocated pages
         */
        empty_zero_page = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
        if (!empty_zero_page)
                panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
                      __func__, PAGE_SIZE, PAGE_SIZE);

        /*
         * Set up SFC/DFC registers
         */
        set_fc(USER_DATA);

#ifdef DEBUG
        printk ("before free_area_init\n");
#endif
        for (i = 0; i < m68k_num_memory; i++)
                if (node_present_pages(i))
                        node_set_state(i, N_NORMAL_MEMORY);

        max_zone_pfn[ZONE_DMA] = memblock_end_of_DRAM();
        free_area_init(max_zone_pfn);
}