/*
 * arch/xtensa/mm/init.c
 *
 * Derived from MIPS, PPC.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2001 - 2005 Tensilica Inc.
 *
 * Chris Zankel <chris@zankel.net>
 * Joe Taylor   <joe@tensilica.com, joetylr@yahoo.com>
 * Marc Gauthier
 * Kevin Chea
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/bootmem.h>
#include <linux/swap.h>
#include <linux/mman.h>
#include <linux/nodemask.h>
#include <linux/mm.h>
#include <linux/slab.h>

#include <asm/pgtable.h>
#include <asm/bootparam.h>
#include <asm/mmu_context.h>
#include <asm/tlb.h>
#include <asm/page.h>
#include <asm/pgalloc.h>


DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);

/* References to section boundaries */

extern char _ftext, _etext, _fdata, _edata, _rodata_end;
extern char __init_begin, __init_end;

/*
 * mem_reserve(start, end, must_exist)
 *
 * Reserve some memory from the memory pool.
 *
 * Parameters:
 *  start       Start of region,
 *  end         End of region,
 *  must_exist  Must exist in memory pool.
 *
 * Returns:
 *  0 (memory area couldn't be mapped)
 * -1 (success)
 */

int __init mem_reserve(unsigned long start, unsigned long end, int must_exist)
{
        int i;

        if (start == end)
                return 0;

        start = start & PAGE_MASK;
        end = PAGE_ALIGN(end);

        for (i = 0; i < sysmem.nr_banks; i++)
                if (start < sysmem.bank[i].end
                    && end >= sysmem.bank[i].start)
                        break;

        if (i == sysmem.nr_banks) {
                if (must_exist)
                        printk (KERN_WARNING "mem_reserve: [0x%0lx, 0x%0lx) "
                                "not in any region!\n", start, end);
                return 0;
        }

        if (start > sysmem.bank[i].start) {
                if (end < sysmem.bank[i].end) {
                        /* split entry */
                        if (sysmem.nr_banks >= SYSMEM_BANKS_MAX)
                                panic("meminfo overflow\n");
                        sysmem.bank[sysmem.nr_banks].start = end;
                        sysmem.bank[sysmem.nr_banks].end = sysmem.bank[i].end;
                        sysmem.nr_banks++;
                }
                sysmem.bank[i].end = start;
        } else {
                if (end < sysmem.bank[i].end)
                        sysmem.bank[i].start = end;
                else {
                        /* remove entry */
                        sysmem.nr_banks--;
                        sysmem.bank[i].start = sysmem.bank[sysmem.nr_banks].start;
                        sysmem.bank[i].end   = sysmem.bank[sysmem.nr_banks].end;
                }
        }
        return -1;
}


/*
 * Initialize the bootmem system and give it all the memory we have available.
 */

void __init bootmem_init(void)
{
        unsigned long pfn;
        unsigned long bootmap_start, bootmap_size;
        int i;

        max_low_pfn = max_pfn = 0;
        min_low_pfn = ~0;

        for (i=0; i < sysmem.nr_banks; i++) {
                pfn = PAGE_ALIGN(sysmem.bank[i].start) >> PAGE_SHIFT;
                if (pfn < min_low_pfn)
                        min_low_pfn = pfn;
                pfn = PAGE_ALIGN(sysmem.bank[i].end - 1) >> PAGE_SHIFT;
                if (pfn > max_pfn)
                        max_pfn = pfn;
        }

        if (min_low_pfn > max_pfn)
                panic("No memory found!\n");

        max_low_pfn = max_pfn < MAX_MEM_PFN >> PAGE_SHIFT ?
                max_pfn : MAX_MEM_PFN >> PAGE_SHIFT;

        /* Find an area to use for the bootmem bitmap. */

        bootmap_size = bootmem_bootmap_pages(max_low_pfn) << PAGE_SHIFT;
        bootmap_start = ~0;

        for (i=0; i<sysmem.nr_banks; i++)
                if (sysmem.bank[i].end - sysmem.bank[i].start >= bootmap_size) {
                        bootmap_start = sysmem.bank[i].start;
                        break;
                }

        if (bootmap_start == ~0UL)
                panic("Cannot find %ld bytes for bootmap\n", bootmap_size);

        /* Reserve the bootmem bitmap area */

        mem_reserve(bootmap_start, bootmap_start + bootmap_size, 1);
        bootmap_size = init_bootmem_node(NODE_DATA(0), min_low_pfn,
                                         bootmap_start >> PAGE_SHIFT,
                                         max_low_pfn);

        /* Add all remaining memory pieces into the bootmem map */

        for (i=0; i<sysmem.nr_banks; i++)
                free_bootmem(sysmem.bank[i].start,
                             sysmem.bank[i].end - sysmem.bank[i].start);

}


void __init paging_init(void)
{
        unsigned long zones_size[MAX_NR_ZONES];
        int i;

        /* All pages are DMA-able, so we put them all in the DMA zone. */

        zones_size[ZONE_DMA] = max_low_pfn;
        for (i = 1; i < MAX_NR_ZONES; i++)
                zones_size[i] = 0;

#ifdef CONFIG_HIGHMEM
        zones_size[ZONE_HIGHMEM] = max_pfn - max_low_pfn;
#endif

        /* Initialize the kernel's page tables. */

        memset(swapper_pg_dir, 0, PAGE_SIZE);

        free_area_init(zones_size);
}

/*
 * Flush the mmu and reset associated register to default values.
 */

void __init init_mmu (void)
{
        /* Writing zeros to the <t>TLBCFG special registers ensure
         * that valid values exist in the register.  For existing
         * PGSZID<w> fields, zero selects the first element of the
         * page-size array.  For nonexistent PGSZID<w> fields, zero is
         * the best value to write.  Also, when changing PGSZID<w>
         * fields, the corresponding TLB must be flushed.
         */
        set_itlbcfg_register (0);
        set_dtlbcfg_register (0);
        flush_tlb_all ();

        /* Set rasid register to a known value. */

        set_rasid_register (ASID_USER_FIRST);

        /* Set PTEVADDR special register to the start of the page
         * table, which is in kernel mappable space (ie. not
         * statically mapped).  This register's value is undefined on
         * reset.
         */
        set_ptevaddr_register (PGTABLE_START);
}

/*
 * Initialize memory pages.
 */

void __init mem_init(void)
{
        unsigned long codesize, reservedpages, datasize, initsize;
        unsigned long highmemsize, tmp, ram;

        max_mapnr = num_physpages = max_low_pfn;
        high_memory = (void *) __va(max_mapnr << PAGE_SHIFT);
        highmemsize = 0;

#ifdef CONFIG_HIGHMEM
#error HIGHGMEM not implemented in init.c
#endif

        totalram_pages += free_all_bootmem();

        reservedpages = ram = 0;
        for (tmp = 0; tmp < max_low_pfn; tmp++) {
                ram++;
                if (PageReserved(mem_map+tmp))
                        reservedpages++;
        }

        codesize =  (unsigned long) &_etext - (unsigned long) &_ftext;
        datasize =  (unsigned long) &_edata - (unsigned long) &_fdata;
        initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;

        printk("Memory: %luk/%luk available (%ldk kernel code, %ldk reserved, "
               "%ldk data, %ldk init %ldk highmem)\n",
               (unsigned long) nr_free_pages() << (PAGE_SHIFT-10),
               ram << (PAGE_SHIFT-10),
               codesize >> 10,
               reservedpages << (PAGE_SHIFT-10),
               datasize >> 10,
               initsize >> 10,
               highmemsize >> 10);
}

void
free_reserved_mem(void *start, void *end)
{
        for (; start < end; start += PAGE_SIZE) {
                ClearPageReserved(virt_to_page(start));
                init_page_count(virt_to_page(start));
                free_page((unsigned long)start);
                totalram_pages++;
        }
}

#ifdef CONFIG_BLK_DEV_INITRD
extern int initrd_is_mapped;

void free_initrd_mem(unsigned long start, unsigned long end)
{
        if (initrd_is_mapped) {
                free_reserved_mem((void*)start, (void*)end);
                printk ("Freeing initrd memory: %ldk freed\n",(end-start)>>10);
        }
}
#endif

void free_initmem(void)
{
        free_reserved_mem(&__init_begin, &__init_end);
        printk("Freeing unused kernel memory: %dk freed\n",
               (&__init_end - &__init_begin) >> 10);
}

struct kmem_cache *pgtable_cache __read_mostly;

static void pgd_ctor(void* addr)
{
        pte_t* ptep = (pte_t*)addr;
        int i;

        for (i = 0; i < 1024; i++, ptep++)
                pte_clear(NULL, 0, ptep);

}

void __init pgtable_cache_init(void)
{
        pgtable_cache = kmem_cache_create("pgd",
                        PAGE_SIZE, PAGE_SIZE,
                        SLAB_HWCACHE_ALIGN,
                        pgd_ctor);
}