/*
 * Copyright (c) 2006-2023, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 * 2022-11-30     WangXiaoyao  the first version
 * 2023-08-19     Shell        Support varea modification handler
 * 2023-10-13     Shell        Replace the page management algorithm of pgmgr
 */

#define DBG_TAG "mm.object"
#define DBG_LVL DBG_INFO
#include "rtdbg.h"

#include <rtthread.h>

#include "mm_aspace.h"
#include "mm_fault.h"
#include "mm_page.h"
#include <mmu.h>

#include <string.h>
#include <stdlib.h>

/** varea based dummy memory object whose data comes directly from page frame */

static const char *get_name(rt_varea_t varea)
{
    return "dummy-mapper";
}

void rt_varea_pgmgr_insert(rt_varea_t varea, void *page_addr)
{
    /* each mapping of page frame in the varea is binding with a reference */
    rt_page_ref_inc(page_addr, 0);
}

/* resource recycling of page frames */
void rt_varea_pgmgr_pop_all(rt_varea_t varea)
{
    rt_aspace_t aspace = varea->aspace;
    char *end_addr = varea->start + varea->size;
    RT_ASSERT(!((long)end_addr & ARCH_PAGE_MASK));

    for (char *iter = varea->start; iter != end_addr; iter += ARCH_PAGE_SIZE)
    {
        void *page_pa = rt_hw_mmu_v2p(aspace, iter);
        char *page_va = rt_kmem_p2v(page_pa);
        if (page_pa != ARCH_MAP_FAILED && page_va)
        {
            rt_hw_mmu_unmap(aspace, iter, ARCH_PAGE_SIZE);
            rt_pages_free(page_va, 0);
        }
    }
}

static void on_page_fault(struct rt_varea *varea, struct rt_aspace_fault_msg *msg)
{
    void *page;
    page = rt_pages_alloc_ext(0, PAGE_ANY_AVAILABLE);

    if (!page)
    {
        LOG_W("%s: page alloc failed", __func__);
        return;
    }

    msg->response.status = MM_FAULT_STATUS_OK;
    msg->response.size = ARCH_PAGE_SIZE;
    msg->response.vaddr = page;
}

static void on_varea_open(struct rt_varea *varea)
{
    varea->data = NULL;
}

static void on_varea_close(struct rt_varea *varea)
{
    /* unmap and dereference page frames in the varea region */
    rt_varea_pgmgr_pop_all(varea);
}

static rt_err_t on_varea_expand(struct rt_varea *varea, void *new_vaddr, rt_size_t size)
{
    return RT_EOK;
}

static void _remove_pages(rt_varea_t varea, void *rm_start, void *rm_end)
{
    void *page_va;

    RT_ASSERT(!((rt_ubase_t)rm_start & ARCH_PAGE_MASK));
    RT_ASSERT(!((rt_ubase_t)rm_end & ARCH_PAGE_MASK));
    while (rm_start != rm_end)
    {
        page_va = rt_hw_mmu_v2p(varea->aspace, rm_start);

        if (page_va != ARCH_MAP_FAILED)
        {
            page_va -= PV_OFFSET;
            LOG_D("%s: free page %p", __func__, page_va);
            rt_varea_unmap_page(varea, rm_start);
            rt_pages_free(page_va, 0);
        }
        rm_start += ARCH_PAGE_SIZE;
    }
}

static rt_err_t on_varea_shrink(rt_varea_t varea, void *new_start, rt_size_t size)
{
    char *varea_start = varea->start;
    void *rm_start;
    void *rm_end;

    if (varea_start == (char *)new_start)
    {
        rm_start = varea_start + size;
        rm_end = varea_start + varea->size;
    }
    else /* if (varea_start < (char *)new_start) */
    {
        RT_ASSERT(varea_start < (char *)new_start);
        rm_start = varea_start;
        rm_end = new_start;
    }

    _remove_pages(varea, rm_start, rm_end);
    return RT_EOK;
}

static rt_err_t on_varea_split(struct rt_varea *existed, void *unmap_start, rt_size_t unmap_len, struct rt_varea *subset)
{
    /* remove the resource in the unmap region, and do nothing for the subset */
    _remove_pages(existed, unmap_start, (char *)unmap_start + unmap_len);

    return RT_EOK;
}

static rt_err_t on_varea_merge(struct rt_varea *merge_to, struct rt_varea *merge_from)
{
    /* do nothing for the migration */
    return RT_EOK;
}

static void page_read(struct rt_varea *varea, struct rt_aspace_io_msg *msg)
{
    char *dst_k;
    rt_aspace_t aspace = varea->aspace;
    dst_k = rt_hw_mmu_v2p(aspace, msg->fault_vaddr);
    if (dst_k != ARCH_MAP_FAILED)
    {
        RT_ASSERT(!((long)dst_k & ARCH_PAGE_MASK));
        dst_k = (void *)((char *)dst_k - PV_OFFSET);
        memcpy(msg->buffer_vaddr, dst_k, ARCH_PAGE_SIZE);
        msg->response.status = MM_FAULT_STATUS_OK;
    }
}

static void page_write(struct rt_varea *varea, struct rt_aspace_io_msg *msg)
{
    void *dst_k;
    rt_aspace_t aspace = varea->aspace;
    dst_k = rt_hw_mmu_v2p(aspace, msg->fault_vaddr);
    if (dst_k != ARCH_MAP_FAILED)
    {
        RT_ASSERT(!((long)dst_k & ARCH_PAGE_MASK));
        dst_k = (void *)((char *)dst_k - PV_OFFSET);
        memcpy(dst_k, msg->buffer_vaddr, ARCH_PAGE_SIZE);
        msg->response.status = MM_FAULT_STATUS_OK;
    }
}

struct rt_mem_obj rt_mm_dummy_mapper = {
    .get_name = get_name,
    .on_page_fault = on_page_fault,
    .hint_free = NULL,
    .on_varea_open = on_varea_open,
    .on_varea_close = on_varea_close,

    .on_varea_shrink = on_varea_shrink,
    .on_varea_split = on_varea_split,
    .on_varea_expand = on_varea_expand,
    .on_varea_merge = on_varea_merge,

    .page_write = page_write,
    .page_read = page_read,
};