/*
 *  linux/arch/arm/mm/init.c
 *
 *  Copyright (C) 1995-1999 Russell King
 */

#include <linux/config.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/swapctl.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#ifdef CONFIG_BLK_DEV_INITRD
#include <linux/blk.h>
#endif

#include <asm/system.h>
#include <asm/segment.h>
#include <asm/pgalloc.h>
#include <asm/dma.h>
#include <asm/hardware.h>
#include <asm/setup.h>

#include "map.h"

static unsigned long totalram_pages;
struct meminfo meminfo;
pgd_t swapper_pg_dir[PTRS_PER_PGD];

/*
 * empty_bad_page is the page that is used for page faults when
 * linux is out-of-memory. Older versions of linux just did a
 * do_exit(), but using this instead means there is less risk
 * for a process dying in kernel mode, possibly leaving a inode
 * unused etc..
 *
 * empty_bad_pte_table is the accompanying page-table: it is
 * initialized to point to BAD_PAGE entries.
 *
 * empty_zero_page is a special page that is used for
 * zero-initialized data and COW.
 */
struct page *empty_zero_page;
struct page *empty_bad_page;
pte_t *empty_bad_pte_table;

pte_t *get_bad_pte_table(void)
{
	pte_t v;
	int i;

	v = pte_mkdirty(mk_pte(empty_bad_page, PAGE_SHARED));

	for (i = 0; i < PTRS_PER_PTE; i++)
		set_pte(empty_bad_pte_table + i, v);

	return empty_bad_pte_table;
}

void __handle_bad_pmd(pmd_t *pmd)
{
	pmd_ERROR(*pmd);
#ifdef CONFIG_DEBUG_ERRORS
	__backtrace();
#endif
	set_pmd(pmd, mk_user_pmd(get_bad_pte_table()));
}

void __handle_bad_pmd_kernel(pmd_t *pmd)
{
	pmd_ERROR(*pmd);
#ifdef CONFIG_DEBUG_ERRORS
	__backtrace();
#endif
	set_pmd(pmd, mk_kernel_pmd(get_bad_pte_table()));
}

#ifndef CONFIG_NO_PGT_CACHE
struct pgtable_cache_struct quicklists;

int do_check_pgt_cache(int low, int high)
{
	int freed = 0;

	if(pgtable_cache_size > high) {
		do {
			if(pgd_quicklist) {
				free_pgd_slow(get_pgd_fast());
				freed++;
			}
			if(pmd_quicklist) {
				free_pmd_slow(get_pmd_fast());
				freed++;
			}
			if(pte_quicklist) {
				free_pte_slow(get_pte_fast());
				 freed++;
			}
		} while(pgtable_cache_size > low);
	}
	return freed;
}
#else
int do_check_pgt_cache(int low, int high)
{
	return 0;
}
#endif

void show_mem(void)
{
	int free = 0, total = 0, reserved = 0;
	int shared = 0, cached = 0;
	struct page *page, *end;

	printk("Mem-info:\n");
	show_free_areas();
	printk("Free swap:       %6dkB\n",nr_swap_pages<<(PAGE_SHIFT-10));

	page = mem_map;
	end  = mem_map + max_mapnr;

	do {
		if (PageSkip(page)) {
			page = page->next_hash;
			if (page == NULL)
				break;
		}
		total++;
		if (PageReserved(page))
			reserved++;
		else if (PageSwapCache(page))
			cached++;
		else if (!page_count(page))
			free++;
		else
			shared += atomic_read(&page->count) - 1;
		page++;
	} while (page < end);

	printk("%d pages of RAM\n", total);
	printk("%d free pages\n", free);
	printk("%d reserved pages\n", reserved);
	printk("%d pages shared\n", shared);
	printk("%d pages swap cached\n", cached);
#ifndef CONFIG_NO_PGT_CACHE
	printk("%ld page tables cached\n", pgtable_cache_size);
#endif
	show_buffers();
}

/*
 * paging_init() sets up the page tables...
 */
void __init paging_init(struct meminfo *mi)
{
	void *zero_page, *bad_page, *bad_table;
	unsigned long zone_size[MAX_NR_ZONES];
	int i;

	memcpy(&meminfo, mi, sizeof(meminfo));

#ifdef CONFIG_CPU_32
#define TABLE_OFFSET	(PTRS_PER_PTE)
#else
#define TABLE_OFFSET	0
#endif
#define TABLE_SIZE	((TABLE_OFFSET + PTRS_PER_PTE) * sizeof(void *))

	/*
	 * allocate what we need for the bad pages
	 */
	zero_page = alloc_bootmem_low_pages(PAGE_SIZE);
	bad_page  = alloc_bootmem_low_pages(PAGE_SIZE);
	bad_table = alloc_bootmem_low_pages(TABLE_SIZE);

	/*
	 * initialise the page tables
	 */
	pagetable_init();
	flush_tlb_all();

	/*
	 * Initialise the zones and mem_map
	 */
	for (i = 0; i < MAX_NR_ZONES; i++)
		zone_size[i] = 0;

	/*
	 * Calculate the size of the zones.  On ARM, we don't have
	 * any problems with DMA or highmem, so all memory is
	 * allocated to the DMA zone.
	 */
	for (i = 0; i < mi->nr_banks; i++) {
		if (mi->bank[i].size) {
			unsigned int end;

			end = (mi->bank[i].start - PHYS_OFFSET +
			       mi->bank[i].size) >> PAGE_SHIFT;
			if (zone_size[0] < end)
				zone_size[0] = end;
		}
	}
	free_area_init(zone_size);

	/*
	 * finish off the bad pages once
	 * the mem_map is initialised
	 */
	memzero(zero_page, PAGE_SIZE);
	memzero(bad_page, PAGE_SIZE);

	empty_zero_page = mem_map + MAP_NR(zero_page);
	empty_bad_page  = mem_map + MAP_NR(bad_page);
	empty_bad_pte_table = ((pte_t *)bad_table) + TABLE_OFFSET;
}

static inline void free_unused_mem_map(void)
{
	struct page *page, *end;

	end = mem_map + max_mapnr;

	for (page = mem_map; page < end; page++) {
		unsigned long low, high;

		if (!PageSkip(page))
			continue;

		low = PAGE_ALIGN((unsigned long)(page + 1));
		if (page->next_hash < page)
			high = ((unsigned long)end) & PAGE_MASK;
		else
			high = ((unsigned long)page->next_hash) & PAGE_MASK;

		while (low < high) {
			ClearPageReserved(mem_map + MAP_NR(low));
			low += PAGE_SIZE;
		}
	}
}

/*
 * mem_init() marks the free areas in the mem_map and tells us how much
 * memory is free.  This is done after various parts of the system have
 * claimed their memory after the kernel image.
 */
void __init mem_init(void)
{
	extern char __init_begin, __init_end, _text, _etext, _end;
	unsigned int codepages, datapages, initpages;
	int i;

	codepages = &_etext - &_text;
	datapages = &_end - &_etext;
	initpages = &__init_end - &__init_begin;

	max_mapnr   = max_low_pfn;
	high_memory = (void *)__va(PHYS_OFFSET + max_low_pfn * PAGE_SIZE);

	/*
	 * We may have non-contiguous memory.  Setup the PageSkip stuff,
	 * and mark the areas of mem_map which can be freed
	 */
	if (meminfo.nr_banks != 1)
		create_memmap_holes();

	/* this will put all unused low memory onto the freelists */
	totalram_pages += free_all_bootmem();

	/*
	 * Since our memory may not be contiguous, calculate the
	 * real number of pages we have in this system
	 */
	printk("Memory:");

	num_physpages = 0;
	for (i = 0; i < meminfo.nr_banks; i++) {
		num_physpages += meminfo.bank[i].size >> PAGE_SHIFT;
		printk(" %ldMB", meminfo.bank[i].size >> 20);
	}

	printk(" = %luMB total\n", num_physpages >> (20 - PAGE_SHIFT));
	printk("Memory: %luKB available (%dK code, %dK data, %dK init)\n",
		(unsigned long) nr_free_pages() << (PAGE_SHIFT-10),
		codepages >> 10, datapages >> 10, initpages >> 10);

	if (PAGE_SIZE >= 16384 && num_physpages <= 128) {
		extern int sysctl_overcommit_memory;
		/*
		 * On a machine this small we won't get
		 * anywhere without overcommit, so turn
		 * it on by default.
		 */
		sysctl_overcommit_memory = 1;
	}
}

static inline void free_area(unsigned long addr, unsigned long end, char *s)
{
	unsigned int size = (end - addr) >> 10;
	struct page *page = mem_map + MAP_NR(addr);

	for (; addr < end; addr += PAGE_SIZE, page ++) {
		ClearPageReserved(page);
		set_page_count(page, 1);
		free_page(addr);
		totalram_pages++;
	}

	if (size)
		printk(" %dk %s", size, s);
}

void free_initmem(void)
{
	extern char __init_begin, __init_end;

	printk("Freeing unused kernel memory:");

	free_area((unsigned long)(&__init_begin),
		  (unsigned long)(&__init_end),
		  "init");

	printk("\n");
}

#ifdef CONFIG_BLK_DEV_INITRD
void free_initrd_mem(unsigned long start, unsigned long end)
{
	unsigned long addr;
	for (addr = start; addr < end; addr += PAGE_SIZE) {
		ClearPageReserved(mem_map + MAP_NR(addr));
		set_page_count(mem_map+MAP_NR(addr), 1);
		free_page(addr);
		totalram_pages++;
	}
	printk ("Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
}
#endif

void si_meminfo(struct sysinfo *val)
{
	val->totalram  = totalram_pages;
	val->sharedram = 0;
	val->freeram   = nr_free_pages();
	val->bufferram = atomic_read(&buffermem_pages);
	val->totalhigh = 0;
	val->freehigh  = 0;
	val->mem_unit  = PAGE_SIZE;
}
