/*
 * helper functions for physically contiguous capture buffers
 *
 * The functions expect the hardware being able to scatter gather
 * (i.e. the buffers are not linear in physical memory, but fragmented
 * into PAGE_SIZE chunks). They also assume the driver does not need
 * to touch the video data.
 *
 * (c) 2009 modified from videobuf-dma-contig by Seen Yang, <yzq.seen@gmail.com>
 *
 * 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 2
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/interrupt.h>

#include <linux/pci.h>
#include <linux/vmalloc.h>
#include <linux/pagemap.h>
#include <asm/page.h>
#include <asm/pgtable.h>

#include <media/videobuf-contig.h>

#define MAGIC_PC_MEM     0x18666666

#define MAGIC_CHECK(is,should)    if (unlikely((is) != (should))) \
    { printk( "magic mismatch: %x (expected %x)\n",is,should); BUG(); }

static int debug;
module_param(debug, int, 0644);

MODULE_DESCRIPTION("helper module to manage video4linux physic continue buffers");
MODULE_AUTHOR("Seen Yang, <yzq.seen@gmail.com> ");
MODULE_LICENSE("GPL");

#define dprintk(level, fmt, arg...)    if (debug >= level) \
    printk(KERN_DEBUG "vbuf-contig: " fmt , ## arg)

struct videobuf_contig_memory
{
    u32 magic;
    dma_addr_t paddr;
    void                *vaddr;
    u32                    size;
};

/* Allocate physic continue memory for buffers */
static void *malloc_contig(u32 buf_size)
{
    void *mem = 0;
    u32 size = PAGE_SIZE << (get_order(buf_size));

mem = (void *)__get_dma_pages(GFP_KERNEL,
                                 get_order(buf_size));
    if (mem) {
        unsigned long adr = (unsigned long)mem;
        while (size > 0) {
            SetPageReserved(virt_to_page(adr));
            adr += PAGE_SIZE;
            size -= PAGE_SIZE;
        }
    } else
        printk( "dma memory can't be alloced!!\n");

return mem;
}

/* Free memory for buffers */
static void free_contig(void *addr, u32 buf_size)
{
    u32 size, adr;

if (!addr)
        return;
    adr = (u32)addr;
    size = PAGE_SIZE << (get_order(buf_size));
    while (size > 0) {
        ClearPageReserved(virt_to_page(adr));
        adr += PAGE_SIZE;
        size -= PAGE_SIZE;
    }
    free_pages((u32)addr, get_order(buf_size));
}

/***************************************************************************/

static void
videobuf_vm_open(struct vm_area_struct *vma)
{
    struct videobuf_mapping *map = vma->vm_private_data;

dprintk(2,"vm_open %p [count=%u,vma=%08lx-%08lx]\n",map,
        map->count,vma->vm_start,vma->vm_end);

map->count++;
}

static void videobuf_vm_close(struct vm_area_struct *vma)
{
    struct videobuf_mapping *map = vma->vm_private_data;
    struct videobuf_queue *q = map->q;
    int i;

dprintk(2,"vm_close %p [count=%u,vma=%08lx-%08lx]\n", map,
        map->count, vma->vm_start, vma->vm_end);
    
    map->count--;
    if (0 == map->count) {
        struct videobuf_contig_memory *mem;

dprintk(1, "munmap %p q=%p\n", map, q);
        mutex_lock(&q->vb_lock);

/* We need first to cancel streams, before unmapping */
        if (q->streaming)
            videobuf_queue_cancel(q);

for (i = 0; i < VIDEO_MAX_FRAME; i++) {
            if (NULL == q->bufs[i])
                continue;

if (q->bufs[i]->map != map)
                continue;

mem = q->bufs[i]->priv;
            if (mem) {
                /* This callback is called only if kernel has
                 allocated memory and this memory is mmapped.
                 In this case, memory should be freed,
                 in order to do memory unmap.
                 */

MAGIC_CHECK(mem->magic, MAGIC_PC_MEM);

dprintk(1, "%s: buf[%d] freeing (%d)\n",
                    __func__, i, mem->paddr);

free_contig(mem->vaddr, mem->size);
                mem->paddr = 0;
                mem->vaddr = NULL;
            }

q->bufs[i]->map = NULL;
            q->bufs[i]->baddr = 0;
        }

kfree(map);

mutex_unlock(&q->vb_lock);
    }

return;
}

static struct vm_operations_struct videobuf_vm_ops =
{
    .open = videobuf_vm_open,
    .close = videobuf_vm_close,
};

/* ---------------------------------------------------------------------
 * contig handlers for the generic methods
 */

/* Allocated area consists on 3 parts:
    struct video_buffer
    struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
    struct videobuf_dma_sg_memory
 */

static void *__videobuf_alloc(size_t size)
{
    struct videobuf_contig_memory *mem;
    struct videobuf_buffer *vb;

vb = kzalloc(size+sizeof(*mem),GFP_KERNEL);

mem = vb->priv = ((char *)vb)+size;
    mem->magic=MAGIC_PC_MEM;

dprintk(1,"%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
        __func__,vb,(long)sizeof(*vb),(long)size-sizeof(*vb),
        mem,(long)sizeof(*mem));

return vb;
}

static int __videobuf_iolock (struct videobuf_queue* q,
             struct videobuf_buffer *vb,
             struct v4l2_framebuffer *fbuf)
{
    struct videobuf_contig_memory *mem = vb->priv;

BUG_ON(!mem);

MAGIC_CHECK(mem->magic, MAGIC_PC_MEM);

switch (vb->memory) {
    case V4L2_MEMORY_MMAP:
        dprintk(1, "%s memory method MMAP\n", __func__);

/* All handling should be done by __videobuf_mmap_mapper() */
        if (!mem->paddr) {
            printk(KERN_ERR "memory is not alloced/mmapped.\n");
            return -EINVAL;
        }
        break;
    case V4L2_MEMORY_USERPTR:

dprintk(1, "%s memory method USERPTR\n", __func__);

if (vb->baddr) {
            printk(KERN_ERR "USERPTR is currently not supported\n");
            return -EINVAL;
        }

/* The only USERPTR currently supported is the one needed for
         read() method.
         */
        
        mem->size = PAGE_ALIGN(vb->size);
        mem->vaddr = malloc_contig(mem->size);
        if (!mem->vaddr) {
            printk(KERN_ERR "malloc_contig (%d pages) failed\n", mem->size);
            return -ENOMEM;
        }
        mem->paddr = virt_to_phys(mem->vaddr);
        
        dprintk(1, "malloc_contig is at addr %d (%d pages)\n",
            mem->paddr, mem->size);

break;
    case V4L2_MEMORY_OVERLAY:
    default:
        dprintk(1, "%s memory method OVERLAY/unknown\n", __func__);

/* Currently, doesn't support V4L2_MEMORY_OVERLAY */
        printk(KERN_ERR "Memory method currently unsupported.\n");
        return -EINVAL;
    }

return 0;
}

static int __videobuf_sync(struct videobuf_queue *q,
             struct videobuf_buffer *buf)
{
    return 0;
}

static int __videobuf_mmap_free(struct videobuf_queue *q)
{
    unsigned int i;

dprintk(1, "%s\n", __func__);
    for (i = 0; i < VIDEO_MAX_FRAME; i++) {
        if (q->bufs[i]) {
            if (q->bufs[i]->map)
                return -EBUSY;
        }
    }

return 0;
}

static int __videobuf_mmap_mapper(struct videobuf_queue *q,
             struct vm_area_struct *vma)
{
    struct videobuf_contig_memory *mem;
    struct videobuf_mapping *map;
    unsigned int first;
    int retval, size;
    unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;

dprintk(1, "%s\n", __func__);
    if (!(vma->vm_flags & VM_WRITE) || !(vma->vm_flags & VM_SHARED))
        return -EINVAL;

/* look for first buffer to map */
    for (first = 0; first < VIDEO_MAX_FRAME; first++) {
        if (NULL == q->bufs[first])
            continue;

if (V4L2_MEMORY_MMAP != q->bufs[first]->memory)
            continue;
        if (q->bufs[first]->boff == offset)
            break;
    }
    if (VIDEO_MAX_FRAME == first) {
        dprintk(1,"mmap app bug: invalid user space offset [offset=0x%lx]\n",
            (vma->vm_pgoff << PAGE_SHIFT));
        return -EINVAL;
    }

/* create mapping + update buffer list */
    map = kzalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
    if (NULL == map)
        return -ENOMEM;

q->bufs[first]->map = map;
    map->start = vma->vm_start;
    map->end = vma->vm_end;
    map->q = q;

q->bufs[first]->baddr = vma->vm_start;

mem = q->bufs[first]->priv;
    BUG_ON(!mem);
    MAGIC_CHECK(mem->magic, MAGIC_PC_MEM);

mem->size = PAGE_ALIGN(q->bufs[first]->bsize);
    mem->vaddr = malloc_contig(mem->size);
    if (!mem->vaddr) {
        printk(KERN_ERR "malloc_contig (%d size) failed\n", mem->size);
        goto error;
    }
    mem->paddr = virt_to_phys(mem->vaddr);
    
    dprintk(1, "malloc_contig is at addr %i (%d size)\n",
        mem->paddr, mem->size);

size = vma->vm_end - vma->vm_start;
    size = (size < mem->size) ? size : mem->size;

/* Try to remap memory */
    vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
    retval = remap_pfn_range(vma, vma->vm_start,
                             mem->paddr >> PAGE_SHIFT,
                             size, vma->vm_page_prot);
    if (retval < 0) {
        printk(KERN_ERR "mmap: remap failed with error %d. ", retval);
        free_contig(mem->vaddr, mem->size);
        goto error;
    }

vma->vm_ops = &videobuf_vm_ops;
    vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
    vma->vm_private_data = map;

dprintk(1,"mmap %p: q=%p %08lx-%08lx (%lx) pgoff %08lx buf %d\n",
        map, q, vma->vm_start, vma->vm_end,
        (long int) q->bufs[first]->bsize,
        vma->vm_pgoff, first);

videobuf_vm_open(vma);

return 0;

error:
    mem = NULL;
    kfree(map);
    return -ENOMEM;
}

static int __videobuf_copy_to_user ( struct videobuf_queue *q,
                char __user *data, size_t count,
                int nonblocking )
{
    struct videobuf_contig_memory *mem = q->read_buf->priv;
    void *vaddr;

BUG_ON(!mem);
    MAGIC_CHECK(mem->magic, MAGIC_PC_MEM);
    BUG_ON(!mem->vaddr);

/* copy to userspace */
    if (count > q->read_buf->size - q->read_off)
        count = q->read_buf->size - q->read_off;

vaddr = mem->vaddr;

if (copy_to_user(data, vaddr + q->read_off, count))
        return -EFAULT;

return count;
}

static int __videobuf_copy_stream ( struct videobuf_queue *q,
                char __user *data, size_t count, size_t pos,
                int vbihack, int nonblocking )
{
    unsigned int *fc;
    struct videobuf_contig_memory *mem=q->read_buf->priv;
    BUG_ON (!mem);
    MAGIC_CHECK(mem->magic,MAGIC_PC_MEM);

if (vbihack) {
        /* dirty, undocumented hack -- pass the frame counter
            * within the last four bytes of each vbi data block.
            * We need that one to maintain backward compatibility
            * to all vbi decoding software out there ... */
        fc = (unsigned int*)mem->vaddr;
        fc += (q->read_buf->size>>2) -1;
        *fc = q->read_buf->field_count >> 1;
        dprintk(1,"vbihack: %d\n",*fc);
    }

/* copy stuff using the common method */
    count = __videobuf_copy_to_user (q, data, count, nonblocking);

if ( (count==-EFAULT) && (0 == pos) )
        return -EFAULT;

return count;
}

static void *__videobuf_to_vmalloc(struct videobuf_buffer *buf)
{
    struct videobuf_contig_memory *mem = buf->priv;

BUG_ON(!mem);
    MAGIC_CHECK(mem->magic, MAGIC_PC_MEM);

return mem->vaddr;
}

static struct videobuf_qtype_ops qops = {
    .magic = MAGIC_QTYPE_OPS,

.alloc = __videobuf_alloc,
    .iolock = __videobuf_iolock,
    .sync = __videobuf_sync,
    .mmap_free = __videobuf_mmap_free,
    .mmap_mapper = __videobuf_mmap_mapper,
    .video_copy_to_user = __videobuf_copy_to_user,
    .copy_stream = __videobuf_copy_stream,
    .vmalloc = __videobuf_to_vmalloc,
};

void videobuf_queue_contig_init(struct videobuf_queue* q,
             struct videobuf_queue_ops *ops,
             void *dev,
             spinlock_t *irqlock,
             enum v4l2_buf_type type,
             enum v4l2_field field,
             unsigned int msize,
             void *priv)
{
    videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
                 priv, &qops);
}

EXPORT_SYMBOL_GPL(videobuf_queue_contig_init);

u32 videobuf_to_contig (struct videobuf_buffer *buf)
{
    struct videobuf_contig_memory *mem=buf->priv;
    BUG_ON (!mem);
    MAGIC_CHECK(mem->magic,MAGIC_PC_MEM);

return mem->paddr;
}
EXPORT_SYMBOL_GPL(videobuf_to_contig);

void videobuf_contig_free (struct videobuf_buffer *buf)
{
    struct videobuf_contig_memory *mem = buf->priv;

/* mmapped memory can't be freed here, otherwise mmapped region
     would be released, while still needed. In this case, the memory
     release should happen inside videobuf_vm_close().
     So, it should free memory only if the memory were allocated for
     read() operation.
     */
    
    if ((buf->memory != V4L2_MEMORY_USERPTR) || !buf->baddr)
        return;
    
    if (!mem)
        return;

MAGIC_CHECK(mem->magic, MAGIC_PC_MEM);

free_contig(mem->vaddr, mem->size);
    mem->paddr = 0;
    mem->vaddr = NULL;

return;
}
EXPORT_SYMBOL_GPL(videobuf_contig_free);