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![Hans Verkuil](/assets/img/avatar_default.png)
The dma-contig and dma-sg memops require a valid struct device for the DMA to be handled correctly. Call WARN_ON and return ERR_PTR(-EINVAL) if it was NULL. Setting the correct device pointer was forgotten in several new driver submissions. This was caught during code review, but it really should be caught in the code. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
783 lines
19 KiB
C
783 lines
19 KiB
C
/*
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* videobuf2-dma-contig.c - DMA contig memory allocator for videobuf2
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*
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* Copyright (C) 2010 Samsung Electronics
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*
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* Author: Pawel Osciak <pawel@osciak.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation.
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*/
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#include <linux/dma-buf.h>
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#include <linux/module.h>
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#include <linux/scatterlist.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/dma-mapping.h>
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#include <media/videobuf2-v4l2.h>
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#include <media/videobuf2-dma-contig.h>
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#include <media/videobuf2-memops.h>
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struct vb2_dc_buf {
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struct device *dev;
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void *vaddr;
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unsigned long size;
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void *cookie;
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dma_addr_t dma_addr;
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unsigned long attrs;
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enum dma_data_direction dma_dir;
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struct sg_table *dma_sgt;
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struct frame_vector *vec;
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/* MMAP related */
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struct vb2_vmarea_handler handler;
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atomic_t refcount;
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struct sg_table *sgt_base;
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/* DMABUF related */
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struct dma_buf_attachment *db_attach;
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};
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/*********************************************/
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/* scatterlist table functions */
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/*********************************************/
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static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt)
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{
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struct scatterlist *s;
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dma_addr_t expected = sg_dma_address(sgt->sgl);
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unsigned int i;
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unsigned long size = 0;
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for_each_sg(sgt->sgl, s, sgt->nents, i) {
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if (sg_dma_address(s) != expected)
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break;
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expected = sg_dma_address(s) + sg_dma_len(s);
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size += sg_dma_len(s);
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}
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return size;
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}
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/*********************************************/
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/* callbacks for all buffers */
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/*********************************************/
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static void *vb2_dc_cookie(void *buf_priv)
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{
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struct vb2_dc_buf *buf = buf_priv;
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return &buf->dma_addr;
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}
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static void *vb2_dc_vaddr(void *buf_priv)
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{
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struct vb2_dc_buf *buf = buf_priv;
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if (!buf->vaddr && buf->db_attach)
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buf->vaddr = dma_buf_vmap(buf->db_attach->dmabuf);
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return buf->vaddr;
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}
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static unsigned int vb2_dc_num_users(void *buf_priv)
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{
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struct vb2_dc_buf *buf = buf_priv;
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return atomic_read(&buf->refcount);
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}
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static void vb2_dc_prepare(void *buf_priv)
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{
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struct vb2_dc_buf *buf = buf_priv;
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struct sg_table *sgt = buf->dma_sgt;
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/* DMABUF exporter will flush the cache for us */
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if (!sgt || buf->db_attach)
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return;
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dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->orig_nents,
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buf->dma_dir);
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}
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static void vb2_dc_finish(void *buf_priv)
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{
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struct vb2_dc_buf *buf = buf_priv;
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struct sg_table *sgt = buf->dma_sgt;
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/* DMABUF exporter will flush the cache for us */
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if (!sgt || buf->db_attach)
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return;
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dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
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}
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/*********************************************/
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/* callbacks for MMAP buffers */
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/*********************************************/
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static void vb2_dc_put(void *buf_priv)
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{
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struct vb2_dc_buf *buf = buf_priv;
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if (!atomic_dec_and_test(&buf->refcount))
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return;
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if (buf->sgt_base) {
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sg_free_table(buf->sgt_base);
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kfree(buf->sgt_base);
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}
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dma_free_attrs(buf->dev, buf->size, buf->cookie, buf->dma_addr,
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buf->attrs);
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put_device(buf->dev);
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kfree(buf);
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}
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static void *vb2_dc_alloc(struct device *dev, unsigned long attrs,
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unsigned long size, enum dma_data_direction dma_dir,
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gfp_t gfp_flags)
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{
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struct vb2_dc_buf *buf;
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if (WARN_ON(!dev))
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return ERR_PTR(-EINVAL);
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buf = kzalloc(sizeof *buf, GFP_KERNEL);
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if (!buf)
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return ERR_PTR(-ENOMEM);
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if (attrs)
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buf->attrs = attrs;
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buf->cookie = dma_alloc_attrs(dev, size, &buf->dma_addr,
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GFP_KERNEL | gfp_flags, buf->attrs);
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if (!buf->cookie) {
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dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size);
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kfree(buf);
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return ERR_PTR(-ENOMEM);
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}
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if ((buf->attrs & DMA_ATTR_NO_KERNEL_MAPPING) == 0)
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buf->vaddr = buf->cookie;
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/* Prevent the device from being released while the buffer is used */
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buf->dev = get_device(dev);
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buf->size = size;
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buf->dma_dir = dma_dir;
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buf->handler.refcount = &buf->refcount;
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buf->handler.put = vb2_dc_put;
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buf->handler.arg = buf;
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atomic_inc(&buf->refcount);
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return buf;
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}
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static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
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{
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struct vb2_dc_buf *buf = buf_priv;
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int ret;
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if (!buf) {
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printk(KERN_ERR "No buffer to map\n");
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return -EINVAL;
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}
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/*
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* dma_mmap_* uses vm_pgoff as in-buffer offset, but we want to
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* map whole buffer
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*/
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vma->vm_pgoff = 0;
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ret = dma_mmap_attrs(buf->dev, vma, buf->cookie,
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buf->dma_addr, buf->size, buf->attrs);
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if (ret) {
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pr_err("Remapping memory failed, error: %d\n", ret);
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return ret;
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}
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vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
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vma->vm_private_data = &buf->handler;
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vma->vm_ops = &vb2_common_vm_ops;
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vma->vm_ops->open(vma);
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pr_debug("%s: mapped dma addr 0x%08lx at 0x%08lx, size %ld\n",
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__func__, (unsigned long)buf->dma_addr, vma->vm_start,
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buf->size);
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return 0;
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}
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/*********************************************/
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/* DMABUF ops for exporters */
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/*********************************************/
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struct vb2_dc_attachment {
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struct sg_table sgt;
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enum dma_data_direction dma_dir;
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};
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static int vb2_dc_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
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struct dma_buf_attachment *dbuf_attach)
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{
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struct vb2_dc_attachment *attach;
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unsigned int i;
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struct scatterlist *rd, *wr;
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struct sg_table *sgt;
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struct vb2_dc_buf *buf = dbuf->priv;
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int ret;
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attach = kzalloc(sizeof(*attach), GFP_KERNEL);
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if (!attach)
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return -ENOMEM;
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sgt = &attach->sgt;
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/* Copy the buf->base_sgt scatter list to the attachment, as we can't
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* map the same scatter list to multiple attachments at the same time.
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*/
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ret = sg_alloc_table(sgt, buf->sgt_base->orig_nents, GFP_KERNEL);
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if (ret) {
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kfree(attach);
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return -ENOMEM;
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}
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rd = buf->sgt_base->sgl;
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wr = sgt->sgl;
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for (i = 0; i < sgt->orig_nents; ++i) {
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sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
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rd = sg_next(rd);
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wr = sg_next(wr);
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}
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attach->dma_dir = DMA_NONE;
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dbuf_attach->priv = attach;
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return 0;
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}
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static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf,
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struct dma_buf_attachment *db_attach)
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{
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struct vb2_dc_attachment *attach = db_attach->priv;
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struct sg_table *sgt;
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if (!attach)
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return;
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sgt = &attach->sgt;
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/* release the scatterlist cache */
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if (attach->dma_dir != DMA_NONE)
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dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
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attach->dma_dir);
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sg_free_table(sgt);
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kfree(attach);
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db_attach->priv = NULL;
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}
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static struct sg_table *vb2_dc_dmabuf_ops_map(
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struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
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{
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struct vb2_dc_attachment *attach = db_attach->priv;
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/* stealing dmabuf mutex to serialize map/unmap operations */
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struct mutex *lock = &db_attach->dmabuf->lock;
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struct sg_table *sgt;
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mutex_lock(lock);
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sgt = &attach->sgt;
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/* return previously mapped sg table */
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if (attach->dma_dir == dma_dir) {
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mutex_unlock(lock);
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return sgt;
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}
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/* release any previous cache */
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if (attach->dma_dir != DMA_NONE) {
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dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
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attach->dma_dir);
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attach->dma_dir = DMA_NONE;
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}
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/* mapping to the client with new direction */
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sgt->nents = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
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dma_dir);
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if (!sgt->nents) {
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pr_err("failed to map scatterlist\n");
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mutex_unlock(lock);
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return ERR_PTR(-EIO);
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}
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attach->dma_dir = dma_dir;
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mutex_unlock(lock);
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return sgt;
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}
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static void vb2_dc_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
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struct sg_table *sgt, enum dma_data_direction dma_dir)
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{
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/* nothing to be done here */
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}
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static void vb2_dc_dmabuf_ops_release(struct dma_buf *dbuf)
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{
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/* drop reference obtained in vb2_dc_get_dmabuf */
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vb2_dc_put(dbuf->priv);
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}
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static void *vb2_dc_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
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{
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struct vb2_dc_buf *buf = dbuf->priv;
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return buf->vaddr ? buf->vaddr + pgnum * PAGE_SIZE : NULL;
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}
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static void *vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf)
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{
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struct vb2_dc_buf *buf = dbuf->priv;
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return buf->vaddr;
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}
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static int vb2_dc_dmabuf_ops_mmap(struct dma_buf *dbuf,
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struct vm_area_struct *vma)
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{
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return vb2_dc_mmap(dbuf->priv, vma);
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}
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static struct dma_buf_ops vb2_dc_dmabuf_ops = {
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.attach = vb2_dc_dmabuf_ops_attach,
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.detach = vb2_dc_dmabuf_ops_detach,
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.map_dma_buf = vb2_dc_dmabuf_ops_map,
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.unmap_dma_buf = vb2_dc_dmabuf_ops_unmap,
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.kmap = vb2_dc_dmabuf_ops_kmap,
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.kmap_atomic = vb2_dc_dmabuf_ops_kmap,
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.vmap = vb2_dc_dmabuf_ops_vmap,
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.mmap = vb2_dc_dmabuf_ops_mmap,
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.release = vb2_dc_dmabuf_ops_release,
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};
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static struct sg_table *vb2_dc_get_base_sgt(struct vb2_dc_buf *buf)
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{
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int ret;
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struct sg_table *sgt;
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sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
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if (!sgt) {
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dev_err(buf->dev, "failed to alloc sg table\n");
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return NULL;
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}
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ret = dma_get_sgtable_attrs(buf->dev, sgt, buf->cookie, buf->dma_addr,
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buf->size, buf->attrs);
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if (ret < 0) {
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dev_err(buf->dev, "failed to get scatterlist from DMA API\n");
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kfree(sgt);
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return NULL;
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}
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return sgt;
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}
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static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv, unsigned long flags)
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{
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struct vb2_dc_buf *buf = buf_priv;
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struct dma_buf *dbuf;
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DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
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exp_info.ops = &vb2_dc_dmabuf_ops;
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exp_info.size = buf->size;
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exp_info.flags = flags;
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exp_info.priv = buf;
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if (!buf->sgt_base)
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buf->sgt_base = vb2_dc_get_base_sgt(buf);
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if (WARN_ON(!buf->sgt_base))
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return NULL;
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dbuf = dma_buf_export(&exp_info);
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if (IS_ERR(dbuf))
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return NULL;
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/* dmabuf keeps reference to vb2 buffer */
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atomic_inc(&buf->refcount);
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return dbuf;
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}
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/*********************************************/
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/* callbacks for USERPTR buffers */
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/*********************************************/
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static void vb2_dc_put_userptr(void *buf_priv)
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{
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struct vb2_dc_buf *buf = buf_priv;
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struct sg_table *sgt = buf->dma_sgt;
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int i;
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struct page **pages;
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if (sgt) {
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/*
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* No need to sync to CPU, it's already synced to the CPU
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* since the finish() memop will have been called before this.
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*/
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dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
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buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
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pages = frame_vector_pages(buf->vec);
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/* sgt should exist only if vector contains pages... */
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BUG_ON(IS_ERR(pages));
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for (i = 0; i < frame_vector_count(buf->vec); i++)
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set_page_dirty_lock(pages[i]);
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sg_free_table(sgt);
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kfree(sgt);
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}
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vb2_destroy_framevec(buf->vec);
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kfree(buf);
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}
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/*
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* For some kind of reserved memory there might be no struct page available,
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* so all that can be done to support such 'pages' is to try to convert
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* pfn to dma address or at the last resort just assume that
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* dma address == physical address (like it has been assumed in earlier version
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* of videobuf2-dma-contig
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*/
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#ifdef __arch_pfn_to_dma
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static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
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{
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return (dma_addr_t)__arch_pfn_to_dma(dev, pfn);
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}
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#elif defined(__pfn_to_bus)
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static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
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{
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return (dma_addr_t)__pfn_to_bus(pfn);
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}
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#elif defined(__pfn_to_phys)
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static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
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{
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return (dma_addr_t)__pfn_to_phys(pfn);
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}
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#else
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static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
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{
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/* really, we cannot do anything better at this point */
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return (dma_addr_t)(pfn) << PAGE_SHIFT;
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}
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#endif
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static void *vb2_dc_get_userptr(struct device *dev, unsigned long vaddr,
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unsigned long size, enum dma_data_direction dma_dir)
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{
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struct vb2_dc_buf *buf;
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struct frame_vector *vec;
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unsigned long offset;
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int n_pages, i;
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int ret = 0;
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struct sg_table *sgt;
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unsigned long contig_size;
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unsigned long dma_align = dma_get_cache_alignment();
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/* Only cache aligned DMA transfers are reliable */
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if (!IS_ALIGNED(vaddr | size, dma_align)) {
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pr_debug("user data must be aligned to %lu bytes\n", dma_align);
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return ERR_PTR(-EINVAL);
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}
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if (!size) {
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pr_debug("size is zero\n");
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return ERR_PTR(-EINVAL);
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}
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if (WARN_ON(!dev))
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return ERR_PTR(-EINVAL);
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buf = kzalloc(sizeof *buf, GFP_KERNEL);
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if (!buf)
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return ERR_PTR(-ENOMEM);
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buf->dev = dev;
|
|
buf->dma_dir = dma_dir;
|
|
|
|
offset = vaddr & ~PAGE_MASK;
|
|
vec = vb2_create_framevec(vaddr, size, dma_dir == DMA_FROM_DEVICE);
|
|
if (IS_ERR(vec)) {
|
|
ret = PTR_ERR(vec);
|
|
goto fail_buf;
|
|
}
|
|
buf->vec = vec;
|
|
n_pages = frame_vector_count(vec);
|
|
ret = frame_vector_to_pages(vec);
|
|
if (ret < 0) {
|
|
unsigned long *nums = frame_vector_pfns(vec);
|
|
|
|
/*
|
|
* Failed to convert to pages... Check the memory is physically
|
|
* contiguous and use direct mapping
|
|
*/
|
|
for (i = 1; i < n_pages; i++)
|
|
if (nums[i-1] + 1 != nums[i])
|
|
goto fail_pfnvec;
|
|
buf->dma_addr = vb2_dc_pfn_to_dma(buf->dev, nums[0]);
|
|
goto out;
|
|
}
|
|
|
|
sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
|
|
if (!sgt) {
|
|
pr_err("failed to allocate sg table\n");
|
|
ret = -ENOMEM;
|
|
goto fail_pfnvec;
|
|
}
|
|
|
|
ret = sg_alloc_table_from_pages(sgt, frame_vector_pages(vec), n_pages,
|
|
offset, size, GFP_KERNEL);
|
|
if (ret) {
|
|
pr_err("failed to initialize sg table\n");
|
|
goto fail_sgt;
|
|
}
|
|
|
|
/*
|
|
* No need to sync to the device, this will happen later when the
|
|
* prepare() memop is called.
|
|
*/
|
|
sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
|
|
buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
|
|
if (sgt->nents <= 0) {
|
|
pr_err("failed to map scatterlist\n");
|
|
ret = -EIO;
|
|
goto fail_sgt_init;
|
|
}
|
|
|
|
contig_size = vb2_dc_get_contiguous_size(sgt);
|
|
if (contig_size < size) {
|
|
pr_err("contiguous mapping is too small %lu/%lu\n",
|
|
contig_size, size);
|
|
ret = -EFAULT;
|
|
goto fail_map_sg;
|
|
}
|
|
|
|
buf->dma_addr = sg_dma_address(sgt->sgl);
|
|
buf->dma_sgt = sgt;
|
|
out:
|
|
buf->size = size;
|
|
|
|
return buf;
|
|
|
|
fail_map_sg:
|
|
dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
|
|
buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
|
|
|
|
fail_sgt_init:
|
|
sg_free_table(sgt);
|
|
|
|
fail_sgt:
|
|
kfree(sgt);
|
|
|
|
fail_pfnvec:
|
|
vb2_destroy_framevec(vec);
|
|
|
|
fail_buf:
|
|
kfree(buf);
|
|
|
|
return ERR_PTR(ret);
|
|
}
|
|
|
|
/*********************************************/
|
|
/* callbacks for DMABUF buffers */
|
|
/*********************************************/
|
|
|
|
static int vb2_dc_map_dmabuf(void *mem_priv)
|
|
{
|
|
struct vb2_dc_buf *buf = mem_priv;
|
|
struct sg_table *sgt;
|
|
unsigned long contig_size;
|
|
|
|
if (WARN_ON(!buf->db_attach)) {
|
|
pr_err("trying to pin a non attached buffer\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (WARN_ON(buf->dma_sgt)) {
|
|
pr_err("dmabuf buffer is already pinned\n");
|
|
return 0;
|
|
}
|
|
|
|
/* get the associated scatterlist for this buffer */
|
|
sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
|
|
if (IS_ERR(sgt)) {
|
|
pr_err("Error getting dmabuf scatterlist\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* checking if dmabuf is big enough to store contiguous chunk */
|
|
contig_size = vb2_dc_get_contiguous_size(sgt);
|
|
if (contig_size < buf->size) {
|
|
pr_err("contiguous chunk is too small %lu/%lu b\n",
|
|
contig_size, buf->size);
|
|
dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
|
|
return -EFAULT;
|
|
}
|
|
|
|
buf->dma_addr = sg_dma_address(sgt->sgl);
|
|
buf->dma_sgt = sgt;
|
|
buf->vaddr = NULL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void vb2_dc_unmap_dmabuf(void *mem_priv)
|
|
{
|
|
struct vb2_dc_buf *buf = mem_priv;
|
|
struct sg_table *sgt = buf->dma_sgt;
|
|
|
|
if (WARN_ON(!buf->db_attach)) {
|
|
pr_err("trying to unpin a not attached buffer\n");
|
|
return;
|
|
}
|
|
|
|
if (WARN_ON(!sgt)) {
|
|
pr_err("dmabuf buffer is already unpinned\n");
|
|
return;
|
|
}
|
|
|
|
if (buf->vaddr) {
|
|
dma_buf_vunmap(buf->db_attach->dmabuf, buf->vaddr);
|
|
buf->vaddr = NULL;
|
|
}
|
|
dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
|
|
|
|
buf->dma_addr = 0;
|
|
buf->dma_sgt = NULL;
|
|
}
|
|
|
|
static void vb2_dc_detach_dmabuf(void *mem_priv)
|
|
{
|
|
struct vb2_dc_buf *buf = mem_priv;
|
|
|
|
/* if vb2 works correctly you should never detach mapped buffer */
|
|
if (WARN_ON(buf->dma_addr))
|
|
vb2_dc_unmap_dmabuf(buf);
|
|
|
|
/* detach this attachment */
|
|
dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
|
|
kfree(buf);
|
|
}
|
|
|
|
static void *vb2_dc_attach_dmabuf(struct device *dev, struct dma_buf *dbuf,
|
|
unsigned long size, enum dma_data_direction dma_dir)
|
|
{
|
|
struct vb2_dc_buf *buf;
|
|
struct dma_buf_attachment *dba;
|
|
|
|
if (dbuf->size < size)
|
|
return ERR_PTR(-EFAULT);
|
|
|
|
if (WARN_ON(!dev))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
buf = kzalloc(sizeof(*buf), GFP_KERNEL);
|
|
if (!buf)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
buf->dev = dev;
|
|
/* create attachment for the dmabuf with the user device */
|
|
dba = dma_buf_attach(dbuf, buf->dev);
|
|
if (IS_ERR(dba)) {
|
|
pr_err("failed to attach dmabuf\n");
|
|
kfree(buf);
|
|
return dba;
|
|
}
|
|
|
|
buf->dma_dir = dma_dir;
|
|
buf->size = size;
|
|
buf->db_attach = dba;
|
|
|
|
return buf;
|
|
}
|
|
|
|
/*********************************************/
|
|
/* DMA CONTIG exported functions */
|
|
/*********************************************/
|
|
|
|
const struct vb2_mem_ops vb2_dma_contig_memops = {
|
|
.alloc = vb2_dc_alloc,
|
|
.put = vb2_dc_put,
|
|
.get_dmabuf = vb2_dc_get_dmabuf,
|
|
.cookie = vb2_dc_cookie,
|
|
.vaddr = vb2_dc_vaddr,
|
|
.mmap = vb2_dc_mmap,
|
|
.get_userptr = vb2_dc_get_userptr,
|
|
.put_userptr = vb2_dc_put_userptr,
|
|
.prepare = vb2_dc_prepare,
|
|
.finish = vb2_dc_finish,
|
|
.map_dmabuf = vb2_dc_map_dmabuf,
|
|
.unmap_dmabuf = vb2_dc_unmap_dmabuf,
|
|
.attach_dmabuf = vb2_dc_attach_dmabuf,
|
|
.detach_dmabuf = vb2_dc_detach_dmabuf,
|
|
.num_users = vb2_dc_num_users,
|
|
};
|
|
EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);
|
|
|
|
/**
|
|
* vb2_dma_contig_set_max_seg_size() - configure DMA max segment size
|
|
* @dev: device for configuring DMA parameters
|
|
* @size: size of DMA max segment size to set
|
|
*
|
|
* To allow mapping the scatter-list into a single chunk in the DMA
|
|
* address space, the device is required to have the DMA max segment
|
|
* size parameter set to a value larger than the buffer size. Otherwise,
|
|
* the DMA-mapping subsystem will split the mapping into max segment
|
|
* size chunks. This function sets the DMA max segment size
|
|
* parameter to let DMA-mapping map a buffer as a single chunk in DMA
|
|
* address space.
|
|
* This code assumes that the DMA-mapping subsystem will merge all
|
|
* scatterlist segments if this is really possible (for example when
|
|
* an IOMMU is available and enabled).
|
|
* Ideally, this parameter should be set by the generic bus code, but it
|
|
* is left with the default 64KiB value due to historical litmiations in
|
|
* other subsystems (like limited USB host drivers) and there no good
|
|
* place to set it to the proper value.
|
|
* This function should be called from the drivers, which are known to
|
|
* operate on platforms with IOMMU and provide access to shared buffers
|
|
* (either USERPTR or DMABUF). This should be done before initializing
|
|
* videobuf2 queue.
|
|
*/
|
|
int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size)
|
|
{
|
|
if (!dev->dma_parms) {
|
|
dev->dma_parms = kzalloc(sizeof(*dev->dma_parms), GFP_KERNEL);
|
|
if (!dev->dma_parms)
|
|
return -ENOMEM;
|
|
}
|
|
if (dma_get_max_seg_size(dev) < size)
|
|
return dma_set_max_seg_size(dev, size);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(vb2_dma_contig_set_max_seg_size);
|
|
|
|
/*
|
|
* vb2_dma_contig_clear_max_seg_size() - release resources for DMA parameters
|
|
* @dev: device for configuring DMA parameters
|
|
*
|
|
* This function releases resources allocated to configure DMA parameters
|
|
* (see vb2_dma_contig_set_max_seg_size() function). It should be called from
|
|
* device drivers on driver remove.
|
|
*/
|
|
void vb2_dma_contig_clear_max_seg_size(struct device *dev)
|
|
{
|
|
kfree(dev->dma_parms);
|
|
dev->dma_parms = NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(vb2_dma_contig_clear_max_seg_size);
|
|
|
|
MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2");
|
|
MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
|
|
MODULE_LICENSE("GPL");
|