/*
 * Copyright (c) 2011-2017 Richard Braun.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *
 * TODO Rework so that pmap update errors can be handled.
 */

#include <kern/assert.h>
#include <kern/cpumap.h>
#include <kern/init.h>
#include <kern/panic.h>
#include <kern/param.h>
#include <kern/stddef.h>
#include <kern/stdint.h>
#include <machine/pmap.h>
#include <machine/types.h>
#include <vm/vm_adv.h>
#include <vm/vm_inherit.h>
#include <vm/vm_kmem.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>
#include <vm/vm_prot.h>

/*
 * Kernel map and storage.
 */
static struct vm_map kernel_map_store;
struct vm_map *kernel_map __read_mostly = &kernel_map_store;

static int
vm_kmem_alloc_check(size_t size)
{
    if (!vm_page_aligned(size)
        || (size == 0)) {
        return -1;
    }

    return 0;
}

static int
vm_kmem_free_check(uintptr_t va, size_t size)
{
    if (!vm_page_aligned(va)) {
        return -1;
    }

    return vm_kmem_alloc_check(size);
}

void *
vm_kmem_alloc_va(size_t size)
{
    int error, flags;
    uintptr_t va;

    assert(vm_kmem_alloc_check(size) == 0);

    va = 0;
    flags = VM_MAP_FLAGS(VM_PROT_ALL, VM_PROT_ALL, VM_INHERIT_NONE,
                         VM_ADV_DEFAULT, 0);
    error = vm_map_enter(kernel_map, &va, size, 0, flags, NULL, 0);

    if (error) {
        return NULL;
    }

    return (void *)va;
}

void
vm_kmem_free_va(void *addr, size_t size)
{
    uintptr_t va;

    va = (uintptr_t)addr;
    assert(vm_kmem_free_check(va, size) == 0);
    vm_map_remove(kernel_map, va, va + vm_page_round(size));
}

void *
vm_kmem_alloc(size_t size)
{
    struct vm_page *page;
    uintptr_t va, start, end;

    size = vm_page_round(size);
    va = (uintptr_t)vm_kmem_alloc_va(size);

    if (va == 0) {
        return NULL;
    }

    for (start = va, end = va + size; start < end; start += PAGE_SIZE) {
        page = vm_page_alloc(0, VM_PAGE_SEL_HIGHMEM, VM_PAGE_KERNEL);

        if (page == NULL) {
            goto error_page;
        }

        pmap_enter(kernel_pmap, start, vm_page_to_pa(page),
                   VM_PROT_READ | VM_PROT_WRITE, PMAP_PEF_GLOBAL);
    }

    pmap_update(kernel_pmap);
    return (void *)va;

error_page:
    size = start - va;

    if (size != 0) {
        pmap_update(kernel_pmap);
        vm_kmem_free((void *)va, size);
    }

    size = end - start;

    if (size != 0) {
        vm_kmem_free_va((void *)start, size);
    }

    return NULL;
}

void
vm_kmem_free(void *addr, size_t size)
{
    const struct cpumap *cpumap;
    struct vm_page *page;
    uintptr_t va, end;
    phys_addr_t pa;
    int error;

    va = (uintptr_t)addr;
    size = vm_page_round(size);
    end = va + size;
    cpumap = cpumap_all();

    while (va < end) {
        error = pmap_kextract(va, &pa);
        assert(!error);
        pmap_remove(kernel_pmap, va, cpumap);
        page = vm_page_lookup(pa);
        assert(page != NULL);
        vm_page_free(page, 0);
        va += PAGE_SIZE;
    }

    pmap_update(kernel_pmap);
    vm_kmem_free_va(addr, size);
}

void *
vm_kmem_map_pa(phys_addr_t pa, size_t size,
               uintptr_t *map_vap, size_t *map_sizep)
{
    uintptr_t offset, map_va;
    size_t map_size;
    phys_addr_t start;

    start = vm_page_trunc(pa);
    map_size = vm_page_round(pa + size) - start;
    map_va = (uintptr_t)vm_kmem_alloc_va(map_size);

    if (map_va == 0) {
        return NULL;
    }

    for (offset = 0; offset < map_size; offset += PAGE_SIZE)
        pmap_enter(kernel_pmap, map_va + offset, start + offset,
                   VM_PROT_READ | VM_PROT_WRITE, PMAP_PEF_GLOBAL);

    pmap_update(kernel_pmap);

    if (map_vap != NULL) {
        *map_vap = map_va;
    }

    if (map_sizep != NULL) {
        *map_sizep = map_size;
    }

    return (void *)(map_va + (uintptr_t)(pa & PAGE_MASK));
}

void
vm_kmem_unmap_pa(uintptr_t map_va, size_t map_size)
{
    const struct cpumap *cpumap;
    uintptr_t va, end;

    cpumap = cpumap_all();
    end = map_va + map_size;

    for (va = map_va; va < end; va += PAGE_SIZE) {
        pmap_remove(kernel_pmap, va, cpumap);
    }

    pmap_update(kernel_pmap);
    vm_kmem_free_va((void *)map_va, map_size);
}