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/*

 * Copyright (C) 2008 Bahadir Balban

 */

#include <l4/lib/list.h>

#include <vm_area.h>

#include <malloc/malloc.h>

#include <fs.h>

/*

 * This is yet unused, it is more of an anticipation

 * of how mmaped devices would be mapped with a pager.

 */

struct mmap_device {

        struct link page_list;  /* Dyn-allocated page list */

        unsigned long pfn_start;        /* Physical pfn start */

        unsigned long pfn_end;          /* Physical pfn end */

};

struct page *memdev_page_in(struct vm_object *vm_obj,

                            unsigned long pfn_offset)

{

        struct vm_file *f = vm_object_to_file(vm_obj);

        struct mmap_device *memdev = f->vnode->inode;

        struct page *page;

        /* Check if its within device boundary */

        if (pfn_offset >= memdev->pfn_end - memdev->pfn_start)

                return PTR_ERR(-1);

        /* Simply return the page if found */

        list_foreach_struct(page, &memdev->page_list, list)

                if (page->offset == pfn_offset)

                        return page;

        /* Otherwise allocate one of our own for that offset and return it */

        page = kzalloc(sizeof(struct page));

        link_init(&page->list);

        spin_lock_init(&page->lock);

        page->offset = pfn_offset;

        page->owner = vm_obj;

        list_insert(&page->list, &memdev->page_list);

        return page;

}

/* All mmapable devices are handled by this */

struct vm_pager memdev_pager = {

        .ops = {

                .page_in = memdev_page_in,

        },

};