videobuf-vmalloc.c

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/*
 * 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, <[email protected]>
 *
 * 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 <[email protected]>");
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);
        videobuf_queue_lock(q);

        /* 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->vaddr);

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

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

        kfree(map);

        videobuf_queue_unlock(q);
    }

    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 struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
{
    struct videobuf_vmalloc_memory *mem;
    struct videobuf_buffer *vb;

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

    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->vaddr) {
            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 (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->vaddr = vmalloc_user(pages);
        if (!mem->vaddr) {
            printk(KERN_ERR "vmalloc (%d pages) failed\n", pages);
            return -ENOMEM;
        }
        dprintk(1, "vmalloc is at addr %p (%d pages)\n",
            mem->vaddr, 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_mmap_mapper(struct videobuf_queue *q,
                  struct videobuf_buffer *buf,
                  struct vm_area_struct *vma)
{
    struct videobuf_vmalloc_memory *mem;
    struct videobuf_mapping *map;
    int retval, pages;

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

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

    buf->map = map;
    map->q     = q;

    buf->baddr = vma->vm_start;

    mem = buf->priv;
    BUG_ON(!mem);
    MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);

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

    /* Try to remap memory */
    retval = remap_vmalloc_range(vma, mem->vaddr, 0);
    if (retval < 0) {
        printk(KERN_ERR "mmap: remap failed with error %d. ", retval);
        vfree(mem->vaddr);
        goto error;
    }

    vma->vm_ops          = &videobuf_vm_ops;
    vma->vm_flags       |= VM_DONTEXPAND | VM_DONTDUMP;
    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)buf->bsize,
        vma->vm_pgoff, buf->i);

    videobuf_vm_open(vma);

    return 0;

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

static struct videobuf_qtype_ops qops = {
    .magic        = MAGIC_QTYPE_OPS,

    .alloc_vb     = __videobuf_alloc_vb,
    .iolock       = __videobuf_iolock,
    .mmap_mapper  = __videobuf_mmap_mapper,
    .vaddr        = videobuf_to_vmalloc,
};

void videobuf_queue_vmalloc_init(struct videobuf_queue *q,
             const struct videobuf_queue_ops *ops,
             struct device *dev,
             spinlock_t *irqlock,
             enum v4l2_buf_type type,
             enum v4l2_field field,
             unsigned int msize,
             void *priv,
             struct mutex *ext_lock)
{
    videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
                 priv, &qops, ext_lock);
}
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->vaddr;
}
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->vaddr);
    mem->vaddr = NULL;

    return;
}
EXPORT_SYMBOL_GPL(videobuf_vmalloc_free);