/*
 * linux/arch/unicore32/mm/mmu.c
 *
 * Code specific to PKUnity SoC and UniCore ISA
 *
 * Copyright (C) 2001-2010 GUAN Xue-tao
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/mman.h>
#include <linux/nodemask.h>
#include <linux/memblock.h>
#include <linux/fs.h>
#include <linux/bootmem.h>
#include <linux/io.h>

#include <asm/cputype.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/sizes.h>
#include <asm/tlb.h>
#include <asm/memblock.h>

#include <mach/map.h>

#include "mm.h"

/*
 * empty_zero_page is a special page that is used for
 * zero-initialized data and COW.
 */
struct page *empty_zero_page;
EXPORT_SYMBOL(empty_zero_page);

/*
 * The pmd table for the upper-most set of pages.
 */
pmd_t *top_pmd;

pgprot_t pgprot_user;
EXPORT_SYMBOL(pgprot_user);

pgprot_t pgprot_kernel;
EXPORT_SYMBOL(pgprot_kernel);

static int __init noalign_setup(char *__unused)
{
        cr_alignment &= ~CR_A;
        cr_no_alignment &= ~CR_A;
        set_cr(cr_alignment);
        return 1;
}
__setup("noalign", noalign_setup);

void adjust_cr(unsigned long mask, unsigned long set)
{
        unsigned long flags;

        mask &= ~CR_A;

        set &= mask;

        local_irq_save(flags);

        cr_no_alignment = (cr_no_alignment & ~mask) | set;
        cr_alignment = (cr_alignment & ~mask) | set;

        set_cr((get_cr() & ~mask) | set);

        local_irq_restore(flags);
}

struct map_desc {
        unsigned long virtual;
        unsigned long pfn;
        unsigned long length;
        unsigned int type;
};

#define PROT_PTE_DEVICE         (PTE_PRESENT | PTE_YOUNG |      \
                                PTE_DIRTY | PTE_READ | PTE_WRITE)
#define PROT_SECT_DEVICE        (PMD_TYPE_SECT | PMD_PRESENT |  \
                                PMD_SECT_READ | PMD_SECT_WRITE)

static struct mem_type mem_types[] = {
        [MT_DEVICE] = {           /* Strongly ordered */
                .prot_pte       = PROT_PTE_DEVICE,
                .prot_l1        = PMD_TYPE_TABLE | PMD_PRESENT,
                .prot_sect      = PROT_SECT_DEVICE,
        },
        /*
         * MT_KUSER: pte for vecpage -- cacheable,
         *       and sect for unigfx mmap -- noncacheable
         */
        [MT_KUSER] = {
                .prot_pte  = PTE_PRESENT | PTE_YOUNG | PTE_DIRTY |
                                PTE_CACHEABLE | PTE_READ | PTE_EXEC,
                .prot_l1   = PMD_TYPE_TABLE | PMD_PRESENT,
                .prot_sect = PROT_SECT_DEVICE,
        },
        [MT_HIGH_VECTORS] = {
                .prot_pte  = PTE_PRESENT | PTE_YOUNG | PTE_DIRTY |
                                PTE_CACHEABLE | PTE_READ | PTE_WRITE |
                                PTE_EXEC,
                .prot_l1   = PMD_TYPE_TABLE | PMD_PRESENT,
        },
        [MT_MEMORY] = {
                .prot_pte  = PTE_PRESENT | PTE_YOUNG | PTE_DIRTY |
                                PTE_WRITE | PTE_EXEC,
                .prot_l1   = PMD_TYPE_TABLE | PMD_PRESENT,
                .prot_sect = PMD_TYPE_SECT | PMD_PRESENT | PMD_SECT_CACHEABLE |
                                PMD_SECT_READ | PMD_SECT_WRITE | PMD_SECT_EXEC,
        },
        [MT_ROM] = {
                .prot_sect = PMD_TYPE_SECT | PMD_PRESENT | PMD_SECT_CACHEABLE |
                                PMD_SECT_READ,
        },
};

const struct mem_type *get_mem_type(unsigned int type)
{
        return type < ARRAY_SIZE(mem_types) ? &mem_types[type] : NULL;
}
EXPORT_SYMBOL(get_mem_type);

/*
 * Adjust the PMD section entries according to the CPU in use.
 */
static void __init build_mem_type_table(void)
{
        pgprot_user   = __pgprot(PTE_PRESENT | PTE_YOUNG | PTE_CACHEABLE);
        pgprot_kernel = __pgprot(PTE_PRESENT | PTE_YOUNG |
                                 PTE_DIRTY | PTE_READ | PTE_WRITE |
                                 PTE_EXEC | PTE_CACHEABLE);
}

#define vectors_base()  (vectors_high() ? 0xffff0000 : 0)

static void __init *early_alloc(unsigned long sz)
{
        void *ptr = __va(memblock_alloc(sz, sz));
        memset(ptr, 0, sz);
        return ptr;
}

static pte_t * __init early_pte_alloc(pmd_t *pmd, unsigned long addr,
                unsigned long prot)
{
        if (pmd_none(*pmd)) {
                pte_t *pte = early_alloc(PTRS_PER_PTE * sizeof(pte_t));
                __pmd_populate(pmd, __pa(pte) | prot);
        }
        BUG_ON(pmd_bad(*pmd));
        return pte_offset_kernel(pmd, addr);
}

static void __init alloc_init_pte(pmd_t *pmd, unsigned long addr,
                                  unsigned long end, unsigned long pfn,
                                  const struct mem_type *type)
{
        pte_t *pte = early_pte_alloc(pmd, addr, type->prot_l1);
        do {
                set_pte(pte, pfn_pte(pfn, __pgprot(type->prot_pte)));
                pfn++;
        } while (pte++, addr += PAGE_SIZE, addr != end);
}

static void __init alloc_init_section(pgd_t *pgd, unsigned long addr,
                                      unsigned long end, unsigned long phys,
                                      const struct mem_type *type)
{
        pmd_t *pmd = pmd_offset((pud_t *)pgd, addr);

        /*
         * Try a section mapping - end, addr and phys must all be aligned
         * to a section boundary.
         */
        if (((addr | end | phys) & ~SECTION_MASK) == 0) {
                pmd_t *p = pmd;

                do {
                        set_pmd(pmd, __pmd(phys | type->prot_sect));
                        phys += SECTION_SIZE;
                } while (pmd++, addr += SECTION_SIZE, addr != end);

                flush_pmd_entry(p);
        } else {
                /*
                 * No need to loop; pte's aren't interested in the
                 * individual L1 entries.
                 */
                alloc_init_pte(pmd, addr, end, __phys_to_pfn(phys), type);
        }
}

/*
 * Create the page directory entries and any necessary
 * page tables for the mapping specified by `md'.  We
 * are able to cope here with varying sizes and address
 * offsets, and we take full advantage of sections.
 */
static void __init create_mapping(struct map_desc *md)
{
        unsigned long phys, addr, length, end;
        const struct mem_type *type;
        pgd_t *pgd;

        if (md->virtual != vectors_base() && md->virtual < TASK_SIZE) {
                printk(KERN_WARNING "BUG: not creating mapping for "
                       "0x%08llx at 0x%08lx in user region\n",
                       __pfn_to_phys((u64)md->pfn), md->virtual);
                return;
        }

        if ((md->type == MT_DEVICE || md->type == MT_ROM) &&
            md->virtual >= PAGE_OFFSET && md->virtual < VMALLOC_END) {
                printk(KERN_WARNING "BUG: mapping for 0x%08llx at 0x%08lx "
                       "overlaps vmalloc space\n",
                       __pfn_to_phys((u64)md->pfn), md->virtual);
        }

        type = &mem_types[md->type];

        addr = md->virtual & PAGE_MASK;
        phys = (unsigned long)__pfn_to_phys(md->pfn);
        length = PAGE_ALIGN(md->length + (md->virtual & ~PAGE_MASK));

        if (type->prot_l1 == 0 && ((addr | phys | length) & ~SECTION_MASK)) {
                printk(KERN_WARNING "BUG: map for 0x%08lx at 0x%08lx can not "
                       "be mapped using pages, ignoring.\n",
                       __pfn_to_phys(md->pfn), addr);
                return;
        }

        pgd = pgd_offset_k(addr);
        end = addr + length;
        do {
                unsigned long next = pgd_addr_end(addr, end);

                alloc_init_section(pgd, addr, next, phys, type);

                phys += next - addr;
                addr = next;
        } while (pgd++, addr != end);
}

static void * __initdata vmalloc_min = (void *)(VMALLOC_END - SZ_128M);

/*
 * vmalloc=size forces the vmalloc area to be exactly 'size'
 * bytes. This can be used to increase (or decrease) the vmalloc
 * area - the default is 128m.
 */
static int __init early_vmalloc(char *arg)
{
        unsigned long vmalloc_reserve = memparse(arg, NULL);

        if (vmalloc_reserve < SZ_16M) {
                vmalloc_reserve = SZ_16M;
                printk(KERN_WARNING
                        "vmalloc area too small, limiting to %luMB\n",
                        vmalloc_reserve >> 20);
        }

        if (vmalloc_reserve > VMALLOC_END - (PAGE_OFFSET + SZ_32M)) {
                vmalloc_reserve = VMALLOC_END - (PAGE_OFFSET + SZ_32M);
                printk(KERN_WARNING
                        "vmalloc area is too big, limiting to %luMB\n",
                        vmalloc_reserve >> 20);
        }

        vmalloc_min = (void *)(VMALLOC_END - vmalloc_reserve);
        return 0;
}
early_param("vmalloc", early_vmalloc);

static phys_addr_t lowmem_limit __initdata = SZ_1G;

static void __init sanity_check_meminfo(void)
{
        int i, j;

        lowmem_limit = __pa(vmalloc_min - 1) + 1;
        memblock_set_current_limit(lowmem_limit);

        for (i = 0, j = 0; i < meminfo.nr_banks; i++) {
                struct membank *bank = &meminfo.bank[j];
                *bank = meminfo.bank[i];
                j++;
        }
        meminfo.nr_banks = j;
}

static inline void prepare_page_table(void)
{
        unsigned long addr;
        phys_addr_t end;

        /*
         * Clear out all the mappings below the kernel image.
         */
        for (addr = 0; addr < MODULES_VADDR; addr += PGDIR_SIZE)
                pmd_clear(pmd_off_k(addr));

        for ( ; addr < PAGE_OFFSET; addr += PGDIR_SIZE)
                pmd_clear(pmd_off_k(addr));

        /*
         * Find the end of the first block of lowmem.
         */
        end = memblock.memory.regions[0].base + memblock.memory.regions[0].size;
        if (end >= lowmem_limit)
                end = lowmem_limit;

        /*
         * Clear out all the kernel space mappings, except for the first
         * memory bank, up to the end of the vmalloc region.
         */
        for (addr = __phys_to_virt(end);
             addr < VMALLOC_END; addr += PGDIR_SIZE)
                pmd_clear(pmd_off_k(addr));
}

/*
 * Reserve the special regions of memory
 */
void __init uc32_mm_memblock_reserve(void)
{
        /*
         * Reserve the page tables.  These are already in use,
         * and can only be in node 0.
         */
        memblock_reserve(__pa(swapper_pg_dir), PTRS_PER_PGD * sizeof(pgd_t));
}

/*
 * Set up device the mappings.  Since we clear out the page tables for all
 * mappings above VMALLOC_END, we will remove any debug device mappings.
 * This means you have to be careful how you debug this function, or any
 * called function.  This means you can't use any function or debugging
 * method which may touch any device, otherwise the kernel _will_ crash.
 */
static void __init devicemaps_init(void)
{
        struct map_desc map;
        unsigned long addr;
        void *vectors;

        /*
         * Allocate the vector page early.
         */
        vectors = early_alloc(PAGE_SIZE);

        for (addr = VMALLOC_END; addr; addr += PGDIR_SIZE)
                pmd_clear(pmd_off_k(addr));

        /*
         * Create a mapping for the machine vectors at the high-vectors
         * location (0xffff0000).  If we aren't using high-vectors, also
         * create a mapping at the low-vectors virtual address.
         */
        map.pfn = __phys_to_pfn(virt_to_phys(vectors));
        map.virtual = VECTORS_BASE;
        map.length = PAGE_SIZE;
        map.type = MT_HIGH_VECTORS;
        create_mapping(&map);

        /*
         * Create a mapping for the kuser page at the special
         * location (0xbfff0000) to the same vectors location.
         */
        map.pfn = __phys_to_pfn(virt_to_phys(vectors));
        map.virtual = KUSER_VECPAGE_BASE;
        map.length = PAGE_SIZE;
        map.type = MT_KUSER;
        create_mapping(&map);

        /*
         * Finally flush the caches and tlb to ensure that we're in a
         * consistent state wrt the writebuffer.  This also ensures that
         * any write-allocated cache lines in the vector page are written
         * back.  After this point, we can start to touch devices again.
         */
        local_flush_tlb_all();
        flush_cache_all();
}

static void __init map_lowmem(void)
{
        struct memblock_region *reg;

        /* Map all the lowmem memory banks. */
        for_each_memblock(memory, reg) {
                phys_addr_t start = reg->base;
                phys_addr_t end = start + reg->size;
                struct map_desc map;

                if (end > lowmem_limit)
                        end = lowmem_limit;
                if (start >= end)
                        break;

                map.pfn = __phys_to_pfn(start);
                map.virtual = __phys_to_virt(start);
                map.length = end - start;
                map.type = MT_MEMORY;

                create_mapping(&map);
        }
}

/*
 * paging_init() sets up the page tables, initialises the zone memory
 * maps, and sets up the zero page, bad page and bad page tables.
 */
void __init paging_init(void)
{
        void *zero_page;

        build_mem_type_table();
        sanity_check_meminfo();
        prepare_page_table();
        map_lowmem();
        devicemaps_init();

        top_pmd = pmd_off_k(0xffff0000);

        /* allocate the zero page. */
        zero_page = early_alloc(PAGE_SIZE);

        bootmem_init();

        empty_zero_page = virt_to_page(zero_page);
        __flush_dcache_page(NULL, empty_zero_page);
}

/*
 * In order to soft-boot, we need to insert a 1:1 mapping in place of
 * the user-mode pages.  This will then ensure that we have predictable
 * results when turning the mmu off
 */
void setup_mm_for_reboot(void)
{
        unsigned long base_pmdval;
        pgd_t *pgd;
        int i;

        /*
         * We need to access to user-mode page tables here. For kernel threads
         * we don't have any user-mode mappings so we use the context that we
         * "borrowed".
         */
        pgd = current->active_mm->pgd;

        base_pmdval = PMD_SECT_WRITE | PMD_SECT_READ | PMD_TYPE_SECT;

        for (i = 0; i < FIRST_USER_PGD_NR + USER_PTRS_PER_PGD; i++, pgd++) {
                unsigned long pmdval = (i << PGDIR_SHIFT) | base_pmdval;
                pmd_t *pmd;

                pmd = pmd_off(pgd, i << PGDIR_SHIFT);
                set_pmd(pmd, __pmd(pmdval));
                flush_pmd_entry(pmd);
        }

        local_flush_tlb_all();
}

/*
 * Take care of architecture specific things when placing a new PTE into
 * a page table, or changing an existing PTE.  Basically, there are two
 * things that we need to take care of:
 *
 *  1. If PG_dcache_clean is not set for the page, we need to ensure
 *     that any cache entries for the kernels virtual memory
 *     range are written back to the page.
 *  2. If we have multiple shared mappings of the same space in
 *     an object, we need to deal with the cache aliasing issues.
 *
 * Note that the pte lock will be held.
 */
void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr,
        pte_t *ptep)
{
        unsigned long pfn = pte_pfn(*ptep);
        struct address_space *mapping;
        struct page *page;

        if (!pfn_valid(pfn))
                return;

        /*
         * The zero page is never written to, so never has any dirty
         * cache lines, and therefore never needs to be flushed.
         */
        page = pfn_to_page(pfn);
        if (page == ZERO_PAGE(0))
                return;

        mapping = page_mapping(page);
        if (!test_and_set_bit(PG_dcache_clean, &page->flags))
                __flush_dcache_page(mapping, page);
        if (mapping)
                if (vma->vm_flags & VM_EXEC)
                        __flush_icache_all();
}