/*
 * helper functions for vmalloc video4linux 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) 2007 Mauro Carvalho Chehab, <mchehab@infradead.org>
 *
 * 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-vmalloc.h>

#define MAGIC_DMABUF   0x17760309
#define MAGIC_VMAL_MEM 0x18221223

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

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

MODULE_DESCRIPTION("helper module to manage video4linux vmalloc buffers");
MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@infradead.org>");
MODULE_LICENSE("GPL");

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


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

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_vmalloc_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_VMAL_MEM);

                                /* vfree is not atomic - can't be
                                   called with IRQ's disabled
                                 */
                                dprintk(1, "%s: buf[%d] freeing (%p)\n",
                                        __func__, i, mem->vmalloc);

                                vfree(mem->vmalloc);
                                mem->vmalloc = NULL;
                        }

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

                kfree(map);

                mutex_unlock(&q->vb_lock);
        }

        return;
}

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

/* ---------------------------------------------------------------------
 * vmalloc 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_vmalloc_memory *mem;
        struct videobuf_buffer *vb;

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

        mem = vb->priv = ((char *)vb)+size;
        mem->magic=MAGIC_VMAL_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_vmalloc_memory *mem = vb->priv;
        int pages;

        BUG_ON(!mem);

        MAGIC_CHECK(mem->magic, MAGIC_VMAL_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->vmalloc) {
                        printk(KERN_ERR "memory is not alloced/mmapped.\n");
                        return -EINVAL;
                }
                break;
        case V4L2_MEMORY_USERPTR:
                pages = PAGE_ALIGN(vb->size);

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

#if 1
                if (vb->baddr) {
                        printk(KERN_ERR "USERPTR is currently not supported\n");
                        return -EINVAL;
                }
#endif

                /* The only USERPTR currently supported is the one needed for
                   read() method.
                 */

                mem->vmalloc = vmalloc_user(pages);
                if (!mem->vmalloc) {
                        printk(KERN_ERR "vmalloc (%d pages) failed\n", pages);
                        return -ENOMEM;
                }
                dprintk(1, "vmalloc is at addr %p (%d pages)\n",
                        mem->vmalloc, pages);

#if 0
                int rc;
                /* Kernel userptr is used also by read() method. In this case,
                   there's no need to remap, since data will be copied to user
                 */
                if (!vb->baddr)
                        return 0;

                /* FIXME: to properly support USERPTR, remap should occur.
                   The code below won't work, since mem->vma = NULL
                 */
                /* Try to remap memory */
                rc = remap_vmalloc_range(mem->vma, (void *)vb->baddr, 0);
                if (rc < 0) {
                        printk(KERN_ERR "mmap: remap failed with error %d. ", rc);
                        return -ENOMEM;
                }
#endif

                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_vmalloc_memory *mem;
        struct videobuf_mapping *map;
        unsigned int first;
        int retval, pages;
        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: offset invalid [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_VMAL_MEM);

        pages = PAGE_ALIGN(vma->vm_end - vma->vm_start);
        mem->vmalloc = vmalloc_user(pages);
        if (!mem->vmalloc) {
                printk(KERN_ERR "vmalloc (%d pages) failed\n", pages);
                goto error;
        }
        dprintk(1, "vmalloc is at addr %p (%d pages)\n",
                mem->vmalloc, pages);

        /* Try to remap memory */
        retval = remap_vmalloc_range(vma, mem->vmalloc, 0);
        if (retval < 0) {
                printk(KERN_ERR "mmap: remap failed with error %d. ", retval);
                vfree(mem->vmalloc);
                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_vmalloc_memory *mem=q->read_buf->priv;
        BUG_ON (!mem);
        MAGIC_CHECK(mem->magic,MAGIC_VMAL_MEM);

        BUG_ON (!mem->vmalloc);

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

        if (copy_to_user(data, mem->vmalloc+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_vmalloc_memory *mem=q->read_buf->priv;
        BUG_ON (!mem);
        MAGIC_CHECK(mem->magic,MAGIC_VMAL_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->vmalloc;
                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 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_vmalloc_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_vmalloc_init);

void *videobuf_to_vmalloc (struct videobuf_buffer *buf)
{
        struct videobuf_vmalloc_memory *mem=buf->priv;
        BUG_ON (!mem);
        MAGIC_CHECK(mem->magic,MAGIC_VMAL_MEM);

        return mem->vmalloc;
}
EXPORT_SYMBOL_GPL(videobuf_to_vmalloc);

void videobuf_vmalloc_free (struct videobuf_buffer *buf)
{
        struct videobuf_vmalloc_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_VMAL_MEM);

        vfree(mem->vmalloc);
        mem->vmalloc = NULL;

        return;
}
EXPORT_SYMBOL_GPL(videobuf_vmalloc_free);

/*
 * Local variables:
 * c-basic-offset: 8
 * End:
 */