videobuf2-dma-contig.c

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/*
 * videobuf2-dma-contig.c - DMA contig memory allocator for videobuf2
 *
 * Copyright (C) 2010 Samsung Electronics
 *
 * Author: Pawel Osciak <[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.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/dma-mapping.h>

#include <media/videobuf2-core.h>
#include <media/videobuf2-dma-contig.h>
#include <media/videobuf2-memops.h>

struct vb2_dc_conf {
    struct device       *dev;
};

struct vb2_dc_buf {
    struct vb2_dc_conf      *conf;
    void                *vaddr;
    dma_addr_t          dma_addr;
    unsigned long           size;
    struct vm_area_struct       *vma;
    atomic_t            refcount;
    struct vb2_vmarea_handler   handler;
};

static void vb2_dma_contig_put(void *buf_priv);

static void *vb2_dma_contig_alloc(void *alloc_ctx, unsigned long size)
{
    struct vb2_dc_conf *conf = alloc_ctx;
    struct vb2_dc_buf *buf;

    buf = kzalloc(sizeof *buf, GFP_KERNEL);
    if (!buf)
        return ERR_PTR(-ENOMEM);

    buf->vaddr = dma_alloc_coherent(conf->dev, size, &buf->dma_addr,
                    GFP_KERNEL);
    if (!buf->vaddr) {
        dev_err(conf->dev, "dma_alloc_coherent of size %ld failed\n",
            size);
        kfree(buf);
        return ERR_PTR(-ENOMEM);
    }

    buf->conf = conf;
    buf->size = size;

    buf->handler.refcount = &buf->refcount;
    buf->handler.put = vb2_dma_contig_put;
    buf->handler.arg = buf;

    atomic_inc(&buf->refcount);

    return buf;
}

static void vb2_dma_contig_put(void *buf_priv)
{
    struct vb2_dc_buf *buf = buf_priv;

    if (atomic_dec_and_test(&buf->refcount)) {
        dma_free_coherent(buf->conf->dev, buf->size, buf->vaddr,
                  buf->dma_addr);
        kfree(buf);
    }
}

static void *vb2_dma_contig_cookie(void *buf_priv)
{
    struct vb2_dc_buf *buf = buf_priv;

    return &buf->dma_addr;
}

static void *vb2_dma_contig_vaddr(void *buf_priv)
{
    struct vb2_dc_buf *buf = buf_priv;
    if (!buf)
        return NULL;

    return buf->vaddr;
}

static unsigned int vb2_dma_contig_num_users(void *buf_priv)
{
    struct vb2_dc_buf *buf = buf_priv;

    return atomic_read(&buf->refcount);
}

static int vb2_dma_contig_mmap(void *buf_priv, struct vm_area_struct *vma)
{
    struct vb2_dc_buf *buf = buf_priv;

    if (!buf) {
        printk(KERN_ERR "No buffer to map\n");
        return -EINVAL;
    }

    return vb2_mmap_pfn_range(vma, buf->dma_addr, buf->size,
                  &vb2_common_vm_ops, &buf->handler);
}

static void *vb2_dma_contig_get_userptr(void *alloc_ctx, unsigned long vaddr,
                    unsigned long size, int write)
{
    struct vb2_dc_buf *buf;
    struct vm_area_struct *vma;
    dma_addr_t dma_addr = 0;
    int ret;

    buf = kzalloc(sizeof *buf, GFP_KERNEL);
    if (!buf)
        return ERR_PTR(-ENOMEM);

    ret = vb2_get_contig_userptr(vaddr, size, &vma, &dma_addr);
    if (ret) {
        printk(KERN_ERR "Failed acquiring VMA for vaddr 0x%08lx\n",
                vaddr);
        kfree(buf);
        return ERR_PTR(ret);
    }

    buf->size = size;
    buf->dma_addr = dma_addr;
    buf->vma = vma;

    return buf;
}

static void vb2_dma_contig_put_userptr(void *mem_priv)
{
    struct vb2_dc_buf *buf = mem_priv;

    if (!buf)
        return;

    vb2_put_vma(buf->vma);
    kfree(buf);
}

const struct vb2_mem_ops vb2_dma_contig_memops = {
    .alloc      = vb2_dma_contig_alloc,
    .put        = vb2_dma_contig_put,
    .cookie     = vb2_dma_contig_cookie,
    .vaddr      = vb2_dma_contig_vaddr,
    .mmap       = vb2_dma_contig_mmap,
    .get_userptr    = vb2_dma_contig_get_userptr,
    .put_userptr    = vb2_dma_contig_put_userptr,
    .num_users  = vb2_dma_contig_num_users,
};
EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);

void *vb2_dma_contig_init_ctx(struct device *dev)
{
    struct vb2_dc_conf *conf;

    conf = kzalloc(sizeof *conf, GFP_KERNEL);
    if (!conf)
        return ERR_PTR(-ENOMEM);

    conf->dev = dev;

    return conf;
}
EXPORT_SYMBOL_GPL(vb2_dma_contig_init_ctx);

void vb2_dma_contig_cleanup_ctx(void *alloc_ctx)
{
    kfree(alloc_ctx);
}
EXPORT_SYMBOL_GPL(vb2_dma_contig_cleanup_ctx);

MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2");
MODULE_AUTHOR("Pawel Osciak <[email protected]>");
MODULE_LICENSE("GPL");