/**
 *
 * @file kmem.c
 * @brief This file contains all functions dealing with kernel memory.
 * @author Guillermo Marcus
 * @date 2009-04-05
 *
 */
#include <linux/version.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/interrupt.h>
#include <linux/pci.h>
#include <linux/cdev.h>
#include <linux/wait.h>
#include <linux/mm.h>
#include <linux/pagemap.h>

#include "base.h"


/**
 *
 * Allocates new kernel memory including the corresponding management structure, makes
 * it available via sysfs if possible.
 *
 */
int pcidriver_kmem_alloc(pcidriver_privdata_t *privdata, kmem_handle_t *kmem_handle)
{
    int flags;
    pcidriver_kmem_entry_t *kmem_entry;
    void *retptr;

    if (kmem_handle->flags&KMEM_FLAG_REUSE) {
        kmem_entry = pcidriver_kmem_find_entry_use(privdata, kmem_handle->use, kmem_handle->item);
        if (kmem_entry) {
            unsigned long flags = kmem_handle->flags;

            if (flags&KMEM_FLAG_TRY) {
                kmem_handle->type = kmem_entry->type;
                kmem_handle->size = kmem_entry->size;
                kmem_handle->align = kmem_entry->align;
            } else {
                if (kmem_handle->type != kmem_entry->type) {
                    mod_info("Invalid type of reusable kmem_entry, currently: %lu, but requested: %lu\n", kmem_entry->type, kmem_handle->type);
                    kmem_handle->type = kmem_entry->type;
                    return -EINVAL;
                }

                if (((kmem_handle->type&PCILIB_KMEM_TYPE_MASK) == PCILIB_KMEM_TYPE_PAGE)&&(kmem_handle->size == 0)) {
                    kmem_handle->size = kmem_entry->size;
                } else if (kmem_handle->size != kmem_entry->size) {
                    mod_info("Invalid size of reusable kmem_entry, currently: %lu, but requested: %lu\n", kmem_entry->size, kmem_handle->size);
                    kmem_handle->size = kmem_entry->size;
                    return -EINVAL;
                }

                if (kmem_handle->align != kmem_entry->align) {
                    mod_info("Invalid alignment of reusable kmem_entry, currently: %lu, but requested: %lu\n", kmem_entry->align, kmem_handle->align);
                    kmem_handle->align = kmem_entry->align;
                    return -EINVAL;
                }

                if (((kmem_entry->mode&KMEM_MODE_EXCLUSIVE)?1:0) != ((flags&KMEM_FLAG_EXCLUSIVE)?1:0)) {
                    mod_info("Invalid mode of reusable kmem_entry\n");
                    kmem_handle->flags = (kmem_entry->mode&KMEM_MODE_EXCLUSIVE)?KMEM_FLAG_EXCLUSIVE:0;
                    return -EINVAL;
                }
            }


            if ((kmem_entry->mode&KMEM_MODE_COUNT)==KMEM_MODE_COUNT) {
                mod_info("Reuse counter of kmem_entry is overflown");
                return -EBUSY;
            }


            kmem_handle->handle_id = kmem_entry->id;
            kmem_handle->ba = (unsigned long)(kmem_entry->dma_handle);
            kmem_handle->pa = virt_to_phys((void*)kmem_entry->cpua);

            kmem_handle->flags = KMEM_FLAG_REUSED;
            if (kmem_entry->refs&KMEM_REF_HW) kmem_handle->flags |= KMEM_FLAG_REUSED_HW;
            if (kmem_entry->mode&KMEM_MODE_PERSISTENT) kmem_handle->flags |= KMEM_FLAG_REUSED_PERSISTENT;

            kmem_entry->mode += 1;
            if (flags&KMEM_FLAG_HW) {
                if ((kmem_entry->refs&KMEM_REF_HW)==0)
                    pcidriver_module_get(privdata);

                kmem_entry->refs |= KMEM_REF_HW;
            }
            if (flags&KMEM_FLAG_PERSISTENT) kmem_entry->mode |= KMEM_MODE_PERSISTENT;

            privdata->kmem_cur_id = kmem_entry->id;

            return 0;
        }

        if (kmem_handle->flags&KMEM_FLAG_TRY) return -ENOENT;
    }

    /* First, allocate zeroed memory for the kmem_entry */
    if ((kmem_entry = kcalloc(1, sizeof(pcidriver_kmem_entry_t), GFP_KERNEL)) == NULL)
        goto kmem_alloc_entry_fail;

    /* Initialize the kmem_entry */
    kmem_entry->id = atomic_inc_return(&privdata->kmem_count) - 1;
    privdata->kmem_cur_id = kmem_entry->id;
    kmem_handle->handle_id = kmem_entry->id;

    kmem_entry->use = kmem_handle->use;
    kmem_entry->item = kmem_handle->item;
    kmem_entry->type = kmem_handle->type;
    kmem_entry->align = kmem_handle->align;
    kmem_entry->direction = PCI_DMA_NONE;

    /* Initialize sysfs if possible */
    if (pcidriver_sysfs_initialize_kmem(privdata, kmem_entry->id, &(kmem_entry->sysfs_attr)) != 0)
        goto kmem_alloc_mem_fail;

    /* ...and allocate the DMA memory */
    /* note this is a memory pair, referencing the same area: the cpu address (cpua)
     * and the PCI bus address (pa). The CPU and PCI addresses may not be the same.
     * The CPU sees only CPU addresses, while the device sees only PCI addresses.
     * CPU address is used for the mmap (internal to the driver), and
     * PCI address is the address passed to the DMA Controller in the device.
     */
    switch (kmem_entry->type&PCILIB_KMEM_TYPE_MASK) {
    case PCILIB_KMEM_TYPE_CONSISTENT:
#ifdef PCIDRIVER_DUMMY_DEVICE
        retptr = kmalloc( kmem_handle->size, GFP_KERNEL);
#else /* PCIDRIVER_DUMMY_DEVICE */
        retptr = pci_alloc_consistent( privdata->pdev, kmem_handle->size, &(kmem_entry->dma_handle) );
#endif /* PCIDRIVER_DUMMY_DEVICE */
        break;
    case PCILIB_KMEM_TYPE_REGION:
        retptr = ioremap(kmem_handle->pa,  kmem_handle->size);
        kmem_entry->dma_handle = kmem_handle->pa;
        if (kmem_entry->type == PCILIB_KMEM_TYPE_REGION_S2C) {
            kmem_entry->direction = PCI_DMA_TODEVICE;
        } else if (kmem_entry->type == PCILIB_KMEM_TYPE_REGION_C2S) {
            kmem_entry->direction = PCI_DMA_FROMDEVICE;
        }
        break;
    case PCILIB_KMEM_TYPE_PAGE:
        flags = GFP_KERNEL;

        if (kmem_handle->size == 0)
            kmem_handle->size = PAGE_SIZE;
        else if (kmem_handle->size%PAGE_SIZE)
            goto kmem_alloc_mem_fail;
        else
            flags |= __GFP_COMP;

        retptr = (void*)__get_free_pages(flags, get_order(kmem_handle->size));
        kmem_entry->dma_handle = 0;

        if (retptr) {
#ifndef PCIDRIVER_DUMMY_DEVICE
            if (kmem_entry->type == PCILIB_KMEM_TYPE_DMA_S2C_PAGE) {
                kmem_entry->direction = PCI_DMA_TODEVICE;
                kmem_entry->dma_handle = pci_map_single(privdata->pdev, retptr, kmem_handle->size, PCI_DMA_TODEVICE);
                if (pci_dma_mapping_error(privdata->pdev, kmem_entry->dma_handle)) {
                    free_pages((unsigned long)retptr, get_order(kmem_handle->size));
                    goto kmem_alloc_mem_fail;
                }
            } else if (kmem_entry->type == PCILIB_KMEM_TYPE_DMA_C2S_PAGE) {
                kmem_entry->direction = PCI_DMA_FROMDEVICE;
                kmem_entry->dma_handle = pci_map_single(privdata->pdev, retptr, kmem_handle->size, PCI_DMA_FROMDEVICE);
                if (pci_dma_mapping_error(privdata->pdev, kmem_entry->dma_handle)) {
                    free_pages((unsigned long)retptr, get_order(kmem_handle->size));
                    goto kmem_alloc_mem_fail;

                }
            }
#endif /* ! PCIDRIVER_DUMMY_DEVICE */
        }

        break;
    default:
        goto kmem_alloc_mem_fail;
    }


    if (retptr == NULL)
        goto kmem_alloc_mem_fail;

    kmem_entry->size = kmem_handle->size;
    kmem_entry->cpua = (unsigned long)retptr;
    kmem_handle->ba = (unsigned long)(kmem_entry->dma_handle);
    kmem_handle->pa = virt_to_phys(retptr);

    kmem_entry->mode = 1;
    if (kmem_handle->flags&KMEM_FLAG_REUSE) {
        kmem_entry->mode |= KMEM_MODE_REUSABLE;
        if (kmem_handle->flags&KMEM_FLAG_EXCLUSIVE) kmem_entry->mode |= KMEM_MODE_EXCLUSIVE;
        if (kmem_handle->flags&KMEM_FLAG_PERSISTENT) kmem_entry->mode |= KMEM_MODE_PERSISTENT;
    }

    kmem_entry->refs = 0;
    if (kmem_handle->flags&KMEM_FLAG_HW) {
        pcidriver_module_get(privdata);

        kmem_entry->refs |= KMEM_REF_HW;
    }

    kmem_handle->flags = 0;

    /* Add the kmem_entry to the list of the device */
    spin_lock( &(privdata->kmemlist_lock) );
    list_add_tail( &(kmem_entry->list), &(privdata->kmem_list) );
    spin_unlock( &(privdata->kmemlist_lock) );

    return 0;

kmem_alloc_mem_fail:
    kfree(kmem_entry);
kmem_alloc_entry_fail:
    return -ENOMEM;
}

static int pcidriver_kmem_free_check(pcidriver_privdata_t *privdata, kmem_handle_t *kmem_handle, pcidriver_kmem_entry_t *kmem_entry) {
    if ((kmem_handle->flags & KMEM_FLAG_FORCE) == 0) {
        if (kmem_entry->mode&KMEM_MODE_COUNT)
            kmem_entry->mode -= 1;

        if (kmem_handle->flags&KMEM_FLAG_HW) {
            if (kmem_entry->refs&KMEM_REF_HW)
                pcidriver_module_put(privdata);

            kmem_entry->refs &= ~KMEM_REF_HW;
        }

        if (kmem_handle->flags&KMEM_FLAG_PERSISTENT)
            kmem_entry->mode &= ~KMEM_MODE_PERSISTENT;

        if (kmem_handle->flags&KMEM_FLAG_REUSE)
            return 0;

        if (kmem_entry->refs) {
            kmem_entry->mode += 1;
            mod_info("can't free referenced kmem_entry, refs = %lx\n", kmem_entry->refs);
            return -EBUSY;
        }

        if (kmem_entry->mode & KMEM_MODE_PERSISTENT) {
            kmem_entry->mode += 1;
            mod_info("can't free persistent kmem_entry\n");
            return -EBUSY;
        }

        if (((kmem_entry->mode&KMEM_MODE_EXCLUSIVE)==0)&&(kmem_entry->mode&KMEM_MODE_COUNT)&&((kmem_handle->flags&KMEM_FLAG_EXCLUSIVE)==0))
            return 0;
    } else {
        if (kmem_entry->refs&KMEM_REF_HW)
            pcidriver_module_put(privdata);

        while (!atomic_add_negative(-1, &(privdata->refs))) pcidriver_module_put(privdata);
        atomic_inc(&(privdata->refs));

    }

    return 1;
}

static int pcidriver_kmem_free_use(pcidriver_privdata_t *privdata, kmem_handle_t *kmem_handle)
{
    int err;
    int failed = 0;
    struct list_head *ptr, *next;
    pcidriver_kmem_entry_t *kmem_entry;

    /* iterate safely over the entries and delete them */
    list_for_each_safe(ptr, next, &(privdata->kmem_list)) {
        kmem_entry = list_entry(ptr, pcidriver_kmem_entry_t, list);
        if (kmem_entry->use == kmem_handle->use) {
            err = pcidriver_kmem_free_check(privdata, kmem_handle, kmem_entry);
            if (err > 0)
                pcidriver_kmem_free_entry(privdata, kmem_entry); 		/* spin lock inside! */
            else
                failed = 1;
        }
    }

    if (failed) {
        mod_info("Some kmem_entries for use %lx are still referenced\n", kmem_handle->use);
        return -EBUSY;
    }

    return 0;
}

/**
 *
 * Called via sysfs, frees kernel memory and the corresponding management structure
 *
 */
int pcidriver_kmem_free( pcidriver_privdata_t *privdata, kmem_handle_t *kmem_handle )
{
    int err;
    pcidriver_kmem_entry_t *kmem_entry;

    if (kmem_handle->flags&KMEM_FLAG_MASS) {
        kmem_handle->flags &= ~KMEM_FLAG_MASS;
        return pcidriver_kmem_free_use(privdata, kmem_handle);
    }

    /* Find the associated kmem_entry for this buffer */
    if ((kmem_entry = pcidriver_kmem_find_entry(privdata, kmem_handle)) == NULL)
        return -EINVAL;					/* kmem_handle is not valid */

    err = pcidriver_kmem_free_check(privdata, kmem_handle, kmem_entry);

    if (err > 0)
        return pcidriver_kmem_free_entry(privdata, kmem_entry);

    return err;
}

/**
 *
 * Called when cleaning up, frees all kernel memory and their corresponding management structure
 *
 */
int pcidriver_kmem_free_all(pcidriver_privdata_t *privdata)
{
//	int failed = 0;
    struct list_head *ptr, *next;
    pcidriver_kmem_entry_t *kmem_entry;

    /* iterate safely over the entries and delete them */
    list_for_each_safe(ptr, next, &(privdata->kmem_list)) {
        kmem_entry = list_entry(ptr, pcidriver_kmem_entry_t, list);
        /*if (kmem_entry->refs)
        	failed = 1;
        else*/
        pcidriver_kmem_free_entry(privdata, kmem_entry); 		/* spin lock inside! */
    }
    /*
    	if (failed) {
    		mod_info("Some kmem_entries are still referenced\n");
    		return -EBUSY;
    	}
    */
    return 0;
}


/**
 *
 * Synchronize memory to/from the device (or in both directions).
 *
 */
int pcidriver_kmem_sync_entry( pcidriver_privdata_t *privdata, pcidriver_kmem_entry_t *kmem_entry, int direction)
{
    if (kmem_entry->direction == PCI_DMA_NONE)
        return -EINVAL;

#ifndef PCIDRIVER_DUMMY_DEVICE
    switch (direction) {
    case PCILIB_KMEM_SYNC_TODEVICE:
        pci_dma_sync_single_for_device( privdata->pdev, kmem_entry->dma_handle, kmem_entry->size, kmem_entry->direction );
        break;
    case PCILIB_KMEM_SYNC_FROMDEVICE:
        pci_dma_sync_single_for_cpu( privdata->pdev, kmem_entry->dma_handle, kmem_entry->size, kmem_entry->direction );
        break;
    case PCILIB_KMEM_SYNC_BIDIRECTIONAL:
        pci_dma_sync_single_for_device( privdata->pdev, kmem_entry->dma_handle, kmem_entry->size, kmem_entry->direction );
        pci_dma_sync_single_for_cpu( privdata->pdev, kmem_entry->dma_handle, kmem_entry->size, kmem_entry->direction );
        break;
    default:
        return -EINVAL;				/* wrong direction parameter */
    }
#endif /* ! PCIDRIVER_DUMMY_DEVICE */

    return 0;	/* success */
}

/**
 *
 * Synchronize memory to/from the device (or in both directions).
 *
 */
int pcidriver_kmem_sync( pcidriver_privdata_t *privdata, kmem_sync_t *kmem_sync )
{
    pcidriver_kmem_entry_t *kmem_entry = NULL;

    /*
     * This is a shortcut to quickly find a next item in big multi-page kernel buffers
     */
    spin_lock(&(privdata->kmemlist_lock));
    if (privdata->kmem_last_sync) {
        if (privdata->kmem_last_sync->id == kmem_sync->handle.handle_id)
            kmem_entry = privdata->kmem_last_sync;
        else {
            privdata->kmem_last_sync = container_of(privdata->kmem_last_sync->list.next, pcidriver_kmem_entry_t, list);

            if (privdata->kmem_last_sync) {
                if (privdata->kmem_last_sync->id == kmem_sync->handle.handle_id)
                    kmem_entry = privdata->kmem_last_sync;
                else
                    privdata->kmem_last_sync = NULL;
            }
        }
    }
    spin_unlock(&(privdata->kmemlist_lock));

    /*
     * If not found go the standard way
     */
    if (!kmem_entry) {
        if ((kmem_entry = pcidriver_kmem_find_entry(privdata, &(kmem_sync->handle))) == NULL)
            return -EINVAL;					/* kmem_handle is not valid */

        spin_lock(&(privdata->kmemlist_lock));
        privdata->kmem_last_sync = kmem_entry;
        spin_unlock(&(privdata->kmemlist_lock));
    }

    return pcidriver_kmem_sync_entry(privdata, kmem_entry, kmem_sync->dir);
}

/**
 *
 * Free the given kmem_entry and its memory.
 *
 */
int pcidriver_kmem_free_entry(pcidriver_privdata_t *privdata, pcidriver_kmem_entry_t *kmem_entry)
{
    pcidriver_sysfs_remove(privdata, &(kmem_entry->sysfs_attr));

    /* Release DMA memory */
    switch (kmem_entry->type&PCILIB_KMEM_TYPE_MASK) {
    case PCILIB_KMEM_TYPE_CONSISTENT:
#ifdef PCIDRIVER_DUMMY_DEVICE
        kfree((void*)(kmem_entry->cpua));
#else /* PCIDRIVER_DUMMY_DEVICE */
        pci_free_consistent( privdata->pdev, kmem_entry->size, (void *)(kmem_entry->cpua), kmem_entry->dma_handle );
#endif /* PCIDRIVER_DUMMY_DEVICE */
        break;
    case PCILIB_KMEM_TYPE_REGION:
        iounmap((void *)(kmem_entry->cpua));
        break;
    case PCILIB_KMEM_TYPE_PAGE:
#ifndef PCIDRIVER_DUMMY_DEVICE
        if (kmem_entry->dma_handle) {
            if (kmem_entry->type == PCILIB_KMEM_TYPE_DMA_S2C_PAGE) {
                pci_unmap_single(privdata->pdev, kmem_entry->dma_handle, kmem_entry->size, PCI_DMA_TODEVICE);
            } else if (kmem_entry->type == PCILIB_KMEM_TYPE_DMA_C2S_PAGE) {
                pci_unmap_single(privdata->pdev, kmem_entry->dma_handle, kmem_entry->size, PCI_DMA_FROMDEVICE);
            }
        }
#endif /* ! PCIDRIVER_DUMMY_DEVICE */
        free_pages((unsigned long)kmem_entry->cpua, get_order(kmem_entry->size));
        break;
    }


    /* Remove the kmem list entry */
    spin_lock( &(privdata->kmemlist_lock) );
    if (privdata->kmem_last_sync == kmem_entry)
        privdata->kmem_last_sync = NULL;
    list_del( &(kmem_entry->list) );
    spin_unlock( &(privdata->kmemlist_lock) );

    /* Release kmem_entry memory */
    kfree(kmem_entry);

    return 0;
}

/**
 *
 * Find the corresponding kmem_entry for the given kmem_handle.
 *
 */
pcidriver_kmem_entry_t *pcidriver_kmem_find_entry(pcidriver_privdata_t *privdata, kmem_handle_t *kmem_handle)
{
    struct list_head *ptr;
    pcidriver_kmem_entry_t *entry, *result = NULL;

    /* should I implement it better using the handle_id? */

    spin_lock(&(privdata->kmemlist_lock));
    list_for_each(ptr, &(privdata->kmem_list)) {
        entry = list_entry(ptr, pcidriver_kmem_entry_t, list);

        if (entry->id == kmem_handle->handle_id) {
            result = entry;
            break;
        }
    }

    spin_unlock(&(privdata->kmemlist_lock));
    return result;
}

/**
 *
 * find the corresponding kmem_entry for the given id.
 *
 */
pcidriver_kmem_entry_t *pcidriver_kmem_find_entry_id(pcidriver_privdata_t *privdata, int id)
{
    struct list_head *ptr;
    pcidriver_kmem_entry_t *entry, *result = NULL;

    spin_lock(&(privdata->kmemlist_lock));
    list_for_each(ptr, &(privdata->kmem_list)) {
        entry = list_entry(ptr, pcidriver_kmem_entry_t, list);

        if (entry->id == id) {
            result = entry;
            break;
        }
    }

    spin_unlock(&(privdata->kmemlist_lock));
    return result;
}

/**
 *
 * find the corresponding kmem_entry for the given use and item.
 *
 */
pcidriver_kmem_entry_t *pcidriver_kmem_find_entry_use(pcidriver_privdata_t *privdata, unsigned long use, unsigned long item)
{
    struct list_head *ptr;
    pcidriver_kmem_entry_t *entry, *result = NULL;

    spin_lock(&(privdata->kmemlist_lock));
    list_for_each(ptr, &(privdata->kmem_list)) {
        entry = list_entry(ptr, pcidriver_kmem_entry_t, list);

        if ((entry->use == use)&&(entry->item == item)&&(entry->mode&KMEM_MODE_REUSABLE)) {
            result = entry;
            break;
        }
    }

    spin_unlock(&(privdata->kmemlist_lock));
    return result;
}


void pcidriver_kmem_mmap_close(struct vm_area_struct *vma) {
    unsigned long vma_size;
    pcidriver_kmem_entry_t *kmem_entry = (pcidriver_kmem_entry_t*)vma->vm_private_data;
    if (kmem_entry) {
        /*
        	if (kmem_entry->id == 0) {
        	    mod_info("refs: %p %p %lx\n", vma, vma->vm_private_data, kmem_entry->refs);
        	    mod_info("kmem_size: %lu vma_size: %lu, s: %lx, e: %lx\n", kmem_entry->size, (vma->vm_end - vma->vm_start), vma->vm_start, vma->vm_end);
        	}
        */

        vma_size = (vma->vm_end - vma->vm_start);

        if (kmem_entry->refs&KMEM_REF_COUNT) {
            kmem_entry->refs -= vma_size / PAGE_SIZE;
        }
    }
}

static struct vm_operations_struct pcidriver_kmem_mmap_ops = {
    .close = pcidriver_kmem_mmap_close
};

/**
 *
 * mmap() kernel memory to userspace.
 *
 */
int pcidriver_mmap_kmem(pcidriver_privdata_t *privdata, struct vm_area_struct *vma)
{
    unsigned long vma_size;
    pcidriver_kmem_entry_t *kmem_entry;
    int ret;

    mod_info_dbg("Entering mmap_kmem\n");

    /* FIXME: Is this really right? Always just the latest one? Can't we identify one? */
    /* Get latest entry on the kmem_list */
    kmem_entry = pcidriver_kmem_find_entry_id(privdata, privdata->kmem_cur_id);
    if (!kmem_entry) {
        mod_info("Trying to mmap a kernel memory buffer without creating it first!\n");
        return -EFAULT;
    }

    mod_info_dbg("Got kmem_entry with id: %d\n", kmem_entry->id);

    /* Check sizes */
    vma_size = (vma->vm_end - vma->vm_start);

    if ((vma_size > kmem_entry->size) &&
            ((kmem_entry->size < PAGE_SIZE) && (vma_size != PAGE_SIZE))) {
        mod_info("kem_entry size(%lu) and vma size do not match(%lu)\n", kmem_entry->size, vma_size);
        return -EINVAL;
    }

    /* reference counting */
    if ((kmem_entry->mode&KMEM_MODE_EXCLUSIVE)&&(kmem_entry->refs&KMEM_REF_COUNT)) {
        mod_info("can't make second mmaping for exclusive kmem_entry\n");
        return -EBUSY;
    }
    if (((kmem_entry->refs&KMEM_REF_COUNT) + (vma_size / PAGE_SIZE)) > KMEM_REF_COUNT) {
        mod_info("maximal amount of references is reached by kmem_entry\n");
        return -EBUSY;
    }

    kmem_entry->refs += vma_size / PAGE_SIZE;

    vma->vm_flags |= (VM_RESERVED);

    // This is coherent memory, so it must not be cached.
    vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

    mod_info_dbg("Mapping address %08lx / PFN %08lx\n",
                 virt_to_phys((void*)kmem_entry->cpua),
                 page_to_pfn(virt_to_page((void*)kmem_entry->cpua)));

    if ((kmem_entry->type&PCILIB_KMEM_TYPE_MASK) == PCILIB_KMEM_TYPE_REGION) {
        ret = remap_pfn_range(vma, vma->vm_start, (kmem_entry->dma_handle >> PAGE_SHIFT), (vma_size < kmem_entry->size)?vma_size:kmem_entry->size, vma->vm_page_prot);
    } else {
        ret = remap_pfn_range(vma, vma->vm_start, page_to_pfn(virt_to_page((void*)(kmem_entry->cpua))), (vma_size < kmem_entry->size)?vma_size:kmem_entry->size, vma->vm_page_prot);
    }

    if (ret) {
        mod_info("kmem remap failed: %d (%lx)\n", ret,kmem_entry->cpua);
        kmem_entry->refs -= 1;
        return -EAGAIN;
    }

    vma->vm_ops = &pcidriver_kmem_mmap_ops;
    vma->vm_private_data = (void*)kmem_entry;

    return ret;
}