/*
 *  arch/s390/mm/vmem.c
 *
 *    Copyright IBM Corp. 2006
 *    Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
 */

#include <linux/bootmem.h>
#include <linux/pfn.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/hugetlb.h>
#include <linux/slab.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/setup.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>

static DEFINE_MUTEX(vmem_mutex);

struct memory_segment {
        struct list_head list;
        unsigned long start;
        unsigned long size;
};

static LIST_HEAD(mem_segs);

static void __ref *vmem_alloc_pages(unsigned int order)
{
        if (slab_is_available())
                return (void *)__get_free_pages(GFP_KERNEL, order);
        return alloc_bootmem_pages((1 << order) * PAGE_SIZE);
}

static inline pud_t *vmem_pud_alloc(void)
{
        pud_t *pud = NULL;

#ifdef CONFIG_64BIT
        pud = vmem_alloc_pages(2);
        if (!pud)
                return NULL;
        clear_table((unsigned long *) pud, _REGION3_ENTRY_EMPTY, PAGE_SIZE * 4);
#endif
        return pud;
}

static inline pmd_t *vmem_pmd_alloc(void)
{
        pmd_t *pmd = NULL;

#ifdef CONFIG_64BIT
        pmd = vmem_alloc_pages(2);
        if (!pmd)
                return NULL;
        clear_table((unsigned long *) pmd, _SEGMENT_ENTRY_EMPTY, PAGE_SIZE * 4);
#endif
        return pmd;
}

static pte_t __ref *vmem_pte_alloc(void)
{
        pte_t *pte;

        if (slab_is_available())
                pte = (pte_t *) page_table_alloc(&init_mm);
        else
                pte = alloc_bootmem(PTRS_PER_PTE * sizeof(pte_t));
        if (!pte)
                return NULL;
        clear_table((unsigned long *) pte, _PAGE_TYPE_EMPTY,
                    PTRS_PER_PTE * sizeof(pte_t));
        return pte;
}

/*
 * Add a physical memory range to the 1:1 mapping.
 */
static int vmem_add_mem(unsigned long start, unsigned long size, int ro)
{
        unsigned long address;
        pgd_t *pg_dir;
        pud_t *pu_dir;
        pmd_t *pm_dir;
        pte_t *pt_dir;
        pte_t  pte;
        int ret = -ENOMEM;

        for (address = start; address < start + size; address += PAGE_SIZE) {
                pg_dir = pgd_offset_k(address);
                if (pgd_none(*pg_dir)) {
                        pu_dir = vmem_pud_alloc();
                        if (!pu_dir)
                                goto out;
                        pgd_populate_kernel(&init_mm, pg_dir, pu_dir);
                }

                pu_dir = pud_offset(pg_dir, address);
                if (pud_none(*pu_dir)) {
                        pm_dir = vmem_pmd_alloc();
                        if (!pm_dir)
                                goto out;
                        pud_populate_kernel(&init_mm, pu_dir, pm_dir);
                }

                pte = mk_pte_phys(address, __pgprot(ro ? _PAGE_RO : 0));
                pm_dir = pmd_offset(pu_dir, address);

#ifdef __s390x__
                if (MACHINE_HAS_HPAGE && !(address & ~HPAGE_MASK) &&
                    (address + HPAGE_SIZE <= start + size) &&
                    (address >= HPAGE_SIZE)) {
                        pte_val(pte) |= _SEGMENT_ENTRY_LARGE;
                        pmd_val(*pm_dir) = pte_val(pte);
                        address += HPAGE_SIZE - PAGE_SIZE;
                        continue;
                }
#endif
                if (pmd_none(*pm_dir)) {
                        pt_dir = vmem_pte_alloc();
                        if (!pt_dir)
                                goto out;
                        pmd_populate_kernel(&init_mm, pm_dir, pt_dir);
                }

                pt_dir = pte_offset_kernel(pm_dir, address);
                *pt_dir = pte;
        }
        ret = 0;
out:
        flush_tlb_kernel_range(start, start + size);
        return ret;
}

/*
 * Remove a physical memory range from the 1:1 mapping.
 * Currently only invalidates page table entries.
 */
static void vmem_remove_range(unsigned long start, unsigned long size)
{
        unsigned long address;
        pgd_t *pg_dir;
        pud_t *pu_dir;
        pmd_t *pm_dir;
        pte_t *pt_dir;
        pte_t  pte;

        pte_val(pte) = _PAGE_TYPE_EMPTY;
        for (address = start; address < start + size; address += PAGE_SIZE) {
                pg_dir = pgd_offset_k(address);
                pu_dir = pud_offset(pg_dir, address);
                if (pud_none(*pu_dir))
                        continue;
                pm_dir = pmd_offset(pu_dir, address);
                if (pmd_none(*pm_dir))
                        continue;

                if (pmd_huge(*pm_dir)) {
                        pmd_clear_kernel(pm_dir);
                        address += HPAGE_SIZE - PAGE_SIZE;
                        continue;
                }

                pt_dir = pte_offset_kernel(pm_dir, address);
                *pt_dir = pte;
        }
        flush_tlb_kernel_range(start, start + size);
}

/*
 * Add a backed mem_map array to the virtual mem_map array.
 */
int __meminit vmemmap_populate(struct page *start, unsigned long nr, int node)
{
        unsigned long address, start_addr, end_addr;
        pgd_t *pg_dir;
        pud_t *pu_dir;
        pmd_t *pm_dir;
        pte_t *pt_dir;
        pte_t  pte;
        int ret = -ENOMEM;

        start_addr = (unsigned long) start;
        end_addr = (unsigned long) (start + nr);

        for (address = start_addr; address < end_addr; address += PAGE_SIZE) {
                pg_dir = pgd_offset_k(address);
                if (pgd_none(*pg_dir)) {
                        pu_dir = vmem_pud_alloc();
                        if (!pu_dir)
                                goto out;
                        pgd_populate_kernel(&init_mm, pg_dir, pu_dir);
                }

                pu_dir = pud_offset(pg_dir, address);
                if (pud_none(*pu_dir)) {
                        pm_dir = vmem_pmd_alloc();
                        if (!pm_dir)
                                goto out;
                        pud_populate_kernel(&init_mm, pu_dir, pm_dir);
                }

                pm_dir = pmd_offset(pu_dir, address);
                if (pmd_none(*pm_dir)) {
                        pt_dir = vmem_pte_alloc();
                        if (!pt_dir)
                                goto out;
                        pmd_populate_kernel(&init_mm, pm_dir, pt_dir);
                }

                pt_dir = pte_offset_kernel(pm_dir, address);
                if (pte_none(*pt_dir)) {
                        unsigned long new_page;

                        new_page =__pa(vmem_alloc_pages(0));
                        if (!new_page)
                                goto out;
                        pte = pfn_pte(new_page >> PAGE_SHIFT, PAGE_KERNEL);
                        *pt_dir = pte;
                }
        }
        memset(start, 0, nr * sizeof(struct page));
        ret = 0;
out:
        flush_tlb_kernel_range(start_addr, end_addr);
        return ret;
}

/*
 * Add memory segment to the segment list if it doesn't overlap with
 * an already present segment.
 */
static int insert_memory_segment(struct memory_segment *seg)
{
        struct memory_segment *tmp;

        if (seg->start + seg->size > VMEM_MAX_PHYS ||
            seg->start + seg->size < seg->start)
                return -ERANGE;

        list_for_each_entry(tmp, &mem_segs, list) {
                if (seg->start >= tmp->start + tmp->size)
                        continue;
                if (seg->start + seg->size <= tmp->start)
                        continue;
                return -ENOSPC;
        }
        list_add(&seg->list, &mem_segs);
        return 0;
}

/*
 * Remove memory segment from the segment list.
 */
static void remove_memory_segment(struct memory_segment *seg)
{
        list_del(&seg->list);
}

static void __remove_shared_memory(struct memory_segment *seg)
{
        remove_memory_segment(seg);
        vmem_remove_range(seg->start, seg->size);
}

int vmem_remove_mapping(unsigned long start, unsigned long size)
{
        struct memory_segment *seg;
        int ret;

        mutex_lock(&vmem_mutex);

        ret = -ENOENT;
        list_for_each_entry(seg, &mem_segs, list) {
                if (seg->start == start && seg->size == size)
                        break;
        }

        if (seg->start != start || seg->size != size)
                goto out;

        ret = 0;
        __remove_shared_memory(seg);
        kfree(seg);
out:
        mutex_unlock(&vmem_mutex);
        return ret;
}

int vmem_add_mapping(unsigned long start, unsigned long size)
{
        struct memory_segment *seg;
        int ret;

        mutex_lock(&vmem_mutex);
        ret = -ENOMEM;
        seg = kzalloc(sizeof(*seg), GFP_KERNEL);
        if (!seg)
                goto out;
        seg->start = start;
        seg->size = size;

        ret = insert_memory_segment(seg);
        if (ret)
                goto out_free;

        ret = vmem_add_mem(start, size, 0);
        if (ret)
                goto out_remove;
        goto out;

out_remove:
        __remove_shared_memory(seg);
out_free:
        kfree(seg);
out:
        mutex_unlock(&vmem_mutex);
        return ret;
}

/*
 * map whole physical memory to virtual memory (identity mapping)
 * we reserve enough space in the vmalloc area for vmemmap to hotplug
 * additional memory segments.
 */
void __init vmem_map_init(void)
{
        unsigned long ro_start, ro_end;
        unsigned long start, end;
        int i;

        ro_start = ((unsigned long)&_stext) & PAGE_MASK;
        ro_end = PFN_ALIGN((unsigned long)&_eshared);
        for (i = 0; i < MEMORY_CHUNKS && memory_chunk[i].size > 0; i++) {
                start = memory_chunk[i].addr;
                end = memory_chunk[i].addr + memory_chunk[i].size;
                if (start >= ro_end || end <= ro_start)
                        vmem_add_mem(start, end - start, 0);
                else if (start >= ro_start && end <= ro_end)
                        vmem_add_mem(start, end - start, 1);
                else if (start >= ro_start) {
                        vmem_add_mem(start, ro_end - start, 1);
                        vmem_add_mem(ro_end, end - ro_end, 0);
                } else if (end < ro_end) {
                        vmem_add_mem(start, ro_start - start, 0);
                        vmem_add_mem(ro_start, end - ro_start, 1);
                } else {
                        vmem_add_mem(start, ro_start - start, 0);
                        vmem_add_mem(ro_start, ro_end - ro_start, 1);
                        vmem_add_mem(ro_end, end - ro_end, 0);
                }
        }
}

/*
 * Convert memory chunk array to a memory segment list so there is a single
 * list that contains both r/w memory and shared memory segments.
 */
static int __init vmem_convert_memory_chunk(void)
{
        struct memory_segment *seg;
        int i;

        mutex_lock(&vmem_mutex);
        for (i = 0; i < MEMORY_CHUNKS; i++) {
                if (!memory_chunk[i].size)
                        continue;
                seg = kzalloc(sizeof(*seg), GFP_KERNEL);
                if (!seg)
                        panic("Out of memory...\n");
                seg->start = memory_chunk[i].addr;
                seg->size = memory_chunk[i].size;
                insert_memory_segment(seg);
        }
        mutex_unlock(&vmem_mutex);
        return 0;
}

core_initcall(vmem_convert_memory_chunk);