[RFCv2 PATCH 2/9] v4l: vb2-dma-contig: update and code refactoring
Tomasz Stanislawski
t.stanislaws at samsung.com
Tue Mar 13 03:17:00 PDT 2012
This patch combines updates and fixes to dma-contig allocator.
Moreover the allocator code was refactored.
The most important changes are:
- functions were reordered
- move compression of scatterlist to separete function
- add support for multichunk but contiguous scatterlists
- simplified implementation of vb2-dma-contig context structure
- let mmap method to use dma_mmap_writecombine
- add support for scatterlist in userptr mode
Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
[mmap method]
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p at samsung.com>
[scatterlist in userptr mode]
Signed-off-by: Kamil Debski <k.debski at samsung.com>
[bugfixing]
Signed-off-by: Tomasz Stanislawski <t.stanislaws at samsung.com>
[core refactoring, helper functions]
Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
---
drivers/media/video/videobuf2-dma-contig.c | 495 +++++++++++++++++++++++-----
1 files changed, 414 insertions(+), 81 deletions(-)
diff --git a/drivers/media/video/videobuf2-dma-contig.c b/drivers/media/video/videobuf2-dma-contig.c
index f17ad98..c1dc043 100644
--- a/drivers/media/video/videobuf2-dma-contig.c
+++ b/drivers/media/video/videobuf2-dma-contig.c
@@ -10,173 +10,506 @@
* the Free Software Foundation.
*/
+#include <linux/dma-buf.h>
+#include <linux/dma-mapping.h>
#include <linux/module.h>
+#include <linux/scatterlist.h>
+#include <linux/sched.h>
#include <linux/slab.h>
-#include <linux/dma-mapping.h>
#include <media/videobuf2-core.h>
#include <media/videobuf2-memops.h>
-struct vb2_dc_conf {
- struct device *dev;
-};
-
struct vb2_dc_buf {
- struct vb2_dc_conf *conf;
+ struct device *dev;
void *vaddr;
- dma_addr_t dma_addr;
unsigned long size;
- struct vm_area_struct *vma;
- atomic_t refcount;
+ dma_addr_t dma_addr;
+ struct sg_table *dma_sgt;
+ enum dma_data_direction dma_dir;
+
+ /* MMAP related */
struct vb2_vmarea_handler handler;
+ atomic_t refcount;
+ struct sg_table *sgt_base;
+
+ /* USERPTR related */
+ struct vm_area_struct *vma;
};
-static void vb2_dma_contig_put(void *buf_priv);
+/*********************************************/
+/* scatterlist table functions */
+/*********************************************/
-static void *vb2_dma_contig_alloc(void *alloc_ctx, unsigned long size)
+static struct sg_table *vb2_dc_pages_to_sgt(struct page **pages,
+ unsigned long n_pages, size_t offset, size_t offset2)
{
- struct vb2_dc_conf *conf = alloc_ctx;
- struct vb2_dc_buf *buf;
+ struct sg_table *sgt;
+ int i, j; /* loop counters */
+ int cur_page, chunks;
+ int ret;
+ struct scatterlist *s;
- buf = kzalloc(sizeof *buf, GFP_KERNEL);
- if (!buf)
+ sgt = kzalloc(sizeof *sgt, GFP_KERNEL);
+ if (!sgt)
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);
+ /* compute number of chunks */
+ chunks = 1;
+ for (i = 1; i < n_pages; ++i)
+ if (pages[i] != pages[i - 1] + 1)
+ ++chunks;
+
+ ret = sg_alloc_table(sgt, chunks, GFP_KERNEL);
+ if (ret) {
+ kfree(sgt);
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;
+ /* merging chunks and putting them into the scatterlist */
+ cur_page = 0;
+ for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
+ size_t size = PAGE_SIZE;
+
+ for (j = cur_page + 1; j < n_pages; ++j) {
+ if (pages[j] != pages[j - 1] + 1)
+ break;
+ size += PAGE_SIZE;
+ }
+
+ /* cut offset if chunk starts at the first page */
+ if (cur_page == 0)
+ size -= offset;
+ /* cut offset2 if chunk ends at the last page */
+ if (j == n_pages)
+ size -= offset2;
+
+ sg_set_page(s, pages[cur_page], size, offset);
+ offset = 0;
+ cur_page = j;
+ }
- atomic_inc(&buf->refcount);
+ return sgt;
+}
- return buf;
+static void vb2_dc_release_sgtable(struct sg_table *sgt)
+{
+ sg_free_table(sgt);
+ kfree(sgt);
}
-static void vb2_dma_contig_put(void *buf_priv)
+static void vb2_dc_put_sgtable(struct sg_table *sgt, int dirty)
{
- struct vb2_dc_buf *buf = buf_priv;
+ struct scatterlist *s;
+ int i, j;
+
+ for_each_sg(sgt->sgl, s, sgt->nents, i) {
+ struct page *page = sg_page(s);
+ int n_pages = PAGE_ALIGN(s->offset + s->length) >> PAGE_SHIFT;
+
+ for (j = 0; j < n_pages; ++j, ++page) {
+ if (dirty)
+ set_page_dirty_lock(page);
+ put_page(page);
+ }
+ }
+
+ vb2_dc_release_sgtable(sgt);
+}
- if (atomic_dec_and_test(&buf->refcount)) {
- dma_free_coherent(buf->conf->dev, buf->size, buf->vaddr,
- buf->dma_addr);
- kfree(buf);
+static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt)
+{
+ struct scatterlist *s;
+ dma_addr_t expected = sg_dma_address(sgt->sgl);
+ int i;
+ unsigned long size = 0;
+
+ for_each_sg(sgt->sgl, s, sgt->nents, i) {
+ if (sg_dma_address(s) != expected)
+ break;
+ expected = sg_dma_address(s) + sg_dma_len(s);
+ size += sg_dma_len(s);
}
+ return size;
}
-static void *vb2_dma_contig_cookie(void *buf_priv)
+/*********************************************/
+/* callbacks for all buffers */
+/*********************************************/
+
+static void *vb2_dc_cookie(void *buf_priv)
{
struct vb2_dc_buf *buf = buf_priv;
return &buf->dma_addr;
}
-static void *vb2_dma_contig_vaddr(void *buf_priv)
+static void *vb2_dc_vaddr(void *buf_priv)
{
struct vb2_dc_buf *buf = buf_priv;
- if (!buf)
- return 0;
return buf->vaddr;
}
-static unsigned int vb2_dma_contig_num_users(void *buf_priv)
+static unsigned int vb2_dc_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)
+static void vb2_dc_prepare(void *buf_priv)
{
struct vb2_dc_buf *buf = buf_priv;
+ struct sg_table *sgt = buf->dma_sgt;
- if (!buf) {
- printk(KERN_ERR "No buffer to map\n");
- return -EINVAL;
- }
+ if (!sgt)
+ return;
+
+ dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
+}
+
+static void vb2_dc_finish(void *buf_priv)
+{
+ struct vb2_dc_buf *buf = buf_priv;
+ struct sg_table *sgt = buf->dma_sgt;
+
+ if (!sgt)
+ return;
+
+ dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
+}
+
+/*********************************************/
+/* callbacks for MMAP buffers */
+/*********************************************/
+
+static void vb2_dc_put(void *buf_priv)
+{
+ struct vb2_dc_buf *buf = buf_priv;
- return vb2_mmap_pfn_range(vma, buf->dma_addr, buf->size,
- &vb2_common_vm_ops, &buf->handler);
+ if (!atomic_dec_and_test(&buf->refcount))
+ return;
+
+ vb2_dc_release_sgtable(buf->sgt_base);
+ dma_free_coherent(buf->dev, buf->size, buf->vaddr,
+ buf->dma_addr);
+ kfree(buf);
}
-static void *vb2_dma_contig_get_userptr(void *alloc_ctx, unsigned long vaddr,
- unsigned long size, int write)
+static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size)
{
+ struct device *dev = alloc_ctx;
struct vb2_dc_buf *buf;
- struct vm_area_struct *vma;
- dma_addr_t dma_addr = 0;
int ret;
+ int n_pages;
+ struct page **pages = NULL;
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->dev = dev;
+ buf->size = size;
+ buf->vaddr = dma_alloc_coherent(buf->dev, buf->size, &buf->dma_addr,
+ GFP_KERNEL);
+
+ ret = -ENOMEM;
+ if (!buf->vaddr) {
+ dev_err(dev, "dma_alloc_coherent of size %ld failed\n",
+ size);
+ goto fail_buf;
}
- buf->size = size;
- buf->dma_addr = dma_addr;
- buf->vma = vma;
+ WARN_ON((unsigned long)buf->vaddr & ~PAGE_MASK);
+ WARN_ON(buf->dma_addr & ~PAGE_MASK);
+
+ n_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+ pages = kmalloc(n_pages * sizeof pages[0], GFP_KERNEL);
+ if (!pages) {
+ printk(KERN_ERR "failed to alloc page table\n");
+ goto fail_dma;
+ }
+
+ ret = dma_get_pages(dev, buf->vaddr, buf->dma_addr, pages, n_pages);
+ if (ret < 0) {
+ printk(KERN_ERR "failed to get buffer pages from DMA API\n");
+ goto fail_pages;
+ }
+ if (ret != n_pages) {
+ ret = -EFAULT;
+ printk(KERN_ERR "failed to get all pages from DMA API\n");
+ goto fail_pages;
+ }
+
+ buf->sgt_base = vb2_dc_pages_to_sgt(pages, n_pages, 0, 0);
+ if (IS_ERR(buf->sgt_base)) {
+ ret = PTR_ERR(buf->sgt_base);
+ printk(KERN_ERR "failed to prepare sg table\n");
+ goto fail_pages;
+ }
+
+ /* pages are no longer needed */
+ kfree(pages);
+
+ buf->handler.refcount = &buf->refcount;
+ buf->handler.put = vb2_dc_put;
+ buf->handler.arg = buf;
+
+ atomic_inc(&buf->refcount);
return buf;
+
+fail_pages:
+ kfree(pages);
+
+fail_dma:
+ dma_free_coherent(buf->dev, buf->size, buf->vaddr, buf->dma_addr);
+
+fail_buf:
+ kfree(buf);
+
+ return ERR_PTR(ret);
+}
+
+static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
+{
+ struct vb2_dc_buf *buf = buf_priv;
+ int ret;
+
+ /*
+ * dma_mmap_* uses vm_pgoff as in-buffer offset, but we want to
+ * map whole buffer
+ */
+ vma->vm_pgoff = 0;
+
+ ret = dma_mmap_writecombine(buf->dev, vma, buf->vaddr,
+ buf->dma_addr, buf->size);
+
+ if (ret) {
+ printk(KERN_ERR "Remapping memory failed, error: %d\n", ret);
+ return ret;
+ }
+
+ vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
+ vma->vm_private_data = &buf->handler;
+ vma->vm_ops = &vb2_common_vm_ops;
+
+ vma->vm_ops->open(vma);
+
+ printk(KERN_DEBUG "%s: mapped dma addr 0x%08lx at 0x%08lx, size %ld\n",
+ __func__, (unsigned long)buf->dma_addr, vma->vm_start,
+ buf->size);
+
+ return 0;
}
-static void vb2_dma_contig_put_userptr(void *mem_priv)
+/*********************************************/
+/* callbacks for USERPTR buffers */
+/*********************************************/
+
+static inline int vma_is_io(struct vm_area_struct *vma)
{
- struct vb2_dc_buf *buf = mem_priv;
+ return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
+}
+static int vb2_dc_get_pages(unsigned long start, struct page **pages,
+ int n_pages, struct vm_area_struct **copy_vma, int write)
+{
+ struct vm_area_struct *vma;
+ int n = 0; /* number of get pages */
+ int ret = -EFAULT;
+
+ /* entering critical section for mm access */
+ down_read(¤t->mm->mmap_sem);
+
+ vma = find_vma(current->mm, start);
+ if (!vma) {
+ printk(KERN_ERR "no vma for address %lu\n", start);
+ goto cleanup;
+ }
+
+ if (vma_is_io(vma)) {
+ unsigned long pfn;
+
+ if (vma->vm_end - start < n_pages * PAGE_SIZE) {
+ printk(KERN_ERR "vma is too small\n");
+ goto cleanup;
+ }
+
+ for (n = 0; n < n_pages; ++n, start += PAGE_SIZE) {
+ ret = follow_pfn(vma, start, &pfn);
+ if (ret) {
+ printk(KERN_ERR "no page for address %lu\n",
+ start);
+ goto cleanup;
+ }
+ pages[n] = pfn_to_page(pfn);
+ get_page(pages[n]);
+ }
+ } else {
+ n = get_user_pages(current, current->mm, start & PAGE_MASK,
+ n_pages, write, 1, pages, NULL);
+ if (n != n_pages) {
+ printk(KERN_ERR "got only %d of %d user pages\n",
+ n, n_pages);
+ goto cleanup;
+ }
+ }
+
+ *copy_vma = vb2_get_vma(vma);
+ if (!*copy_vma) {
+ printk(KERN_ERR "failed to copy vma\n");
+ ret = -ENOMEM;
+ goto cleanup;
+ }
+
+ /* leaving critical section for mm access */
+ up_read(¤t->mm->mmap_sem);
+
+ return 0;
+
+cleanup:
+ up_read(¤t->mm->mmap_sem);
+
+ /* putting user pages if used, can be done wothout the lock */
+ while (n)
+ put_page(pages[--n]);
+
+ return ret;
+}
+
+static void vb2_dc_put_userptr(void *buf_priv)
+{
+ struct vb2_dc_buf *buf = buf_priv;
+ struct sg_table *sgt = buf->dma_sgt;
+
+ dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
+ vb2_dc_put_sgtable(sgt, !vma_is_io(buf->vma));
+ vb2_put_vma(buf->vma);
+ kfree(buf);
+}
+
+static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
+ unsigned long size, int write)
+{
+ struct vb2_dc_buf *buf;
+ unsigned long start, end, offset, offset2;
+ struct page **pages;
+ int n_pages;
+ int ret = 0;
+ struct sg_table *sgt;
+ unsigned long contig_size;
+
+ buf = kzalloc(sizeof *buf, GFP_KERNEL);
if (!buf)
- return;
+ return ERR_PTR(-ENOMEM);
+
+ buf->dev = alloc_ctx;
+ buf->dma_dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+
+ start = (unsigned long)vaddr & PAGE_MASK;
+ offset = (unsigned long)vaddr & ~PAGE_MASK;
+ end = PAGE_ALIGN((unsigned long)vaddr + size);
+ offset2 = end - (unsigned long)vaddr - size;
+ n_pages = (end - start) >> PAGE_SHIFT;
+
+ pages = kmalloc(n_pages * sizeof pages[0], GFP_KERNEL);
+ if (!pages) {
+ ret = -ENOMEM;
+ printk(KERN_ERR "failed to allocate pages table\n");
+ goto fail_buf;
+ }
+
+ /* extract page list from userspace mapping */
+ ret = vb2_dc_get_pages(start, pages, n_pages, &buf->vma, write);
+ if (ret) {
+ printk(KERN_ERR "failed to get user pages\n");
+ goto fail_pages;
+ }
+
+ sgt = vb2_dc_pages_to_sgt(pages, n_pages, offset, offset2);
+ if (!sgt) {
+ printk(KERN_ERR "failed to create scatterlist table\n");
+ ret = -ENOMEM;
+ goto fail_get_pages;
+ }
+
+ /* pages are no longer needed */
+ kfree(pages);
+ pages = NULL;
+
+ sgt->nents = dma_map_sg(buf->dev, sgt->sgl, sgt->orig_nents,
+ buf->dma_dir);
+ if (sgt->nents <= 0) {
+ printk(KERN_ERR "failed to map scatterlist\n");
+ ret = -EIO;
+ goto fail_sgt;
+ }
+
+ contig_size = vb2_dc_get_contiguous_size(sgt);
+ if (contig_size < size) {
+ printk(KERN_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->size = size;
+ buf->dma_sgt = sgt;
+
+ atomic_inc(&buf->refcount);
+
+ return buf;
+
+fail_map_sg:
+ dma_unmap_sg(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
+fail_sgt:
+ vb2_dc_put_sgtable(sgt, 0);
+
+fail_get_pages:
+ while (pages && n_pages)
+ put_page(pages[--n_pages]);
vb2_put_vma(buf->vma);
+
+fail_pages:
+ kfree(pages); /* kfree is NULL-proof */
+
+fail_buf:
kfree(buf);
+
+ return ERR_PTR(ret);
}
+/*********************************************/
+/* DMA CONTIG exported functions */
+/*********************************************/
+
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,
+ .alloc = vb2_dc_alloc,
+ .put = vb2_dc_put,
+ .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,
+ .num_users = vb2_dc_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;
+ return dev;
}
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);
--
1.7.5.4
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