[media] v4l: videobuf2: add DMA scatter/gather allocator
Andrzej Pietrasiewicz [Mon, 29 Nov 2010 14:53:34 +0000 (11:53 -0300)]
Add an implementation of DMA scatter/gather allocator and handling
routines for videobuf2.

For mmap operation mode it is implemented on top of
alloc_page + sg_set_page/_free_page.

For userptr operation mode it is implemented on top of
get_user_pages + sg_set_page/put_page.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
CC: Pawel Osciak <pawel@osciak.com>
Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/Kconfig
drivers/media/video/Makefile
drivers/media/video/videobuf2-dma-sg.c [new file with mode: 0644]
include/media/videobuf2-dma-sg.h [new file with mode: 0644]

index b64183e..8710d90 100644 (file)
@@ -60,6 +60,12 @@ config VIDEOBUF2_VMALLOC
        select VIDEOBUF2_MEMOPS
        tristate
 
+
+config VIDEOBUF2_DMA_SG
+       #depends on HAS_DMA
+       select VIDEOBUF2_CORE
+       select VIDEOBUF2_MEMOPS
+       tristate
 #
 # Multimedia Video device configuration
 #
index 106d40b..40833fe 100644 (file)
@@ -115,6 +115,7 @@ obj-$(CONFIG_VIDEOBUF2_CORE)                += videobuf2-core.o
 obj-$(CONFIG_VIDEOBUF2_MEMOPS)         += videobuf2-memops.o
 obj-$(CONFIG_VIDEOBUF2_VMALLOC)                += videobuf2-vmalloc.o
 obj-$(CONFIG_VIDEOBUF2_DMA_CONTIG)     += videobuf2-dma-contig.o
+obj-$(CONFIG_VIDEOBUF2_DMA_SG)         += videobuf2-dma-sg.o
 
 obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
 
diff --git a/drivers/media/video/videobuf2-dma-sg.c b/drivers/media/video/videobuf2-dma-sg.c
new file mode 100644 (file)
index 0000000..20b5c5d
--- /dev/null
@@ -0,0 +1,292 @@
+/*
+ * videobuf2-dma-sg.c - dma scatter/gather memory allocator for videobuf2
+ *
+ * Copyright (C) 2010 Samsung Electronics
+ *
+ * Author: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
+ *
+ * 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/mm.h>
+#include <linux/scatterlist.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+
+#include <media/videobuf2-core.h>
+#include <media/videobuf2-memops.h>
+#include <media/videobuf2-dma-sg.h>
+
+struct vb2_dma_sg_buf {
+       void                            *vaddr;
+       struct page                     **pages;
+       int                             write;
+       int                             offset;
+       struct vb2_dma_sg_desc          sg_desc;
+       atomic_t                        refcount;
+       struct vb2_vmarea_handler       handler;
+};
+
+static void vb2_dma_sg_put(void *buf_priv);
+
+static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size)
+{
+       struct vb2_dma_sg_buf *buf;
+       int i;
+
+       buf = kzalloc(sizeof *buf, GFP_KERNEL);
+       if (!buf)
+               return NULL;
+
+       buf->vaddr = NULL;
+       buf->write = 0;
+       buf->offset = 0;
+       buf->sg_desc.size = size;
+       buf->sg_desc.num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+       buf->sg_desc.sglist = vmalloc(buf->sg_desc.num_pages *
+                                     sizeof(*buf->sg_desc.sglist));
+       if (!buf->sg_desc.sglist)
+               goto fail_sglist_alloc;
+       memset(buf->sg_desc.sglist, 0, buf->sg_desc.num_pages *
+              sizeof(*buf->sg_desc.sglist));
+       sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
+
+       buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
+                            GFP_KERNEL);
+       if (!buf->pages)
+               goto fail_pages_array_alloc;
+
+       for (i = 0; i < buf->sg_desc.num_pages; ++i) {
+               buf->pages[i] = alloc_page(GFP_KERNEL);
+               if (NULL == buf->pages[i])
+                       goto fail_pages_alloc;
+               sg_set_page(&buf->sg_desc.sglist[i],
+                           buf->pages[i], PAGE_SIZE, 0);
+       }
+
+       buf->handler.refcount = &buf->refcount;
+       buf->handler.put = vb2_dma_sg_put;
+       buf->handler.arg = buf;
+
+       atomic_inc(&buf->refcount);
+
+       printk(KERN_DEBUG "%s: Allocated buffer of %d pages\n",
+               __func__, buf->sg_desc.num_pages);
+
+       if (!buf->vaddr)
+               buf->vaddr = vm_map_ram(buf->pages,
+                                       buf->sg_desc.num_pages,
+                                       -1,
+                                       PAGE_KERNEL);
+       return buf;
+
+fail_pages_alloc:
+       while (--i >= 0)
+               __free_page(buf->pages[i]);
+
+fail_pages_array_alloc:
+       vfree(buf->sg_desc.sglist);
+
+fail_sglist_alloc:
+       kfree(buf);
+       return NULL;
+}
+
+static void vb2_dma_sg_put(void *buf_priv)
+{
+       struct vb2_dma_sg_buf *buf = buf_priv;
+       int i = buf->sg_desc.num_pages;
+
+       if (atomic_dec_and_test(&buf->refcount)) {
+               printk(KERN_DEBUG "%s: Freeing buffer of %d pages\n", __func__,
+                       buf->sg_desc.num_pages);
+               if (buf->vaddr)
+                       vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
+               vfree(buf->sg_desc.sglist);
+               while (--i >= 0)
+                       __free_page(buf->pages[i]);
+               kfree(buf->pages);
+               kfree(buf);
+       }
+}
+
+static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
+                                   unsigned long size, int write)
+{
+       struct vb2_dma_sg_buf *buf;
+       unsigned long first, last;
+       int num_pages_from_user, i;
+
+       buf = kzalloc(sizeof *buf, GFP_KERNEL);
+       if (!buf)
+               return NULL;
+
+       buf->vaddr = NULL;
+       buf->write = write;
+       buf->offset = vaddr & ~PAGE_MASK;
+       buf->sg_desc.size = size;
+
+       first = (vaddr           & PAGE_MASK) >> PAGE_SHIFT;
+       last  = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
+       buf->sg_desc.num_pages = last - first + 1;
+
+       buf->sg_desc.sglist = vmalloc(
+               buf->sg_desc.num_pages * sizeof(*buf->sg_desc.sglist));
+       if (!buf->sg_desc.sglist)
+               goto userptr_fail_sglist_alloc;
+
+       memset(buf->sg_desc.sglist, 0,
+               buf->sg_desc.num_pages * sizeof(*buf->sg_desc.sglist));
+       sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
+
+       buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
+                            GFP_KERNEL);
+       if (!buf->pages)
+               goto userptr_fail_pages_array_alloc;
+
+       down_read(&current->mm->mmap_sem);
+       num_pages_from_user = get_user_pages(current, current->mm,
+                                            vaddr & PAGE_MASK,
+                                            buf->sg_desc.num_pages,
+                                            write,
+                                            1, /* force */
+                                            buf->pages,
+                                            NULL);
+       up_read(&current->mm->mmap_sem);
+       if (num_pages_from_user != buf->sg_desc.num_pages)
+               goto userptr_fail_get_user_pages;
+
+       sg_set_page(&buf->sg_desc.sglist[0], buf->pages[0],
+                   PAGE_SIZE - buf->offset, buf->offset);
+       size -= PAGE_SIZE - buf->offset;
+       for (i = 1; i < buf->sg_desc.num_pages; ++i) {
+               sg_set_page(&buf->sg_desc.sglist[i], buf->pages[i],
+                           min_t(size_t, PAGE_SIZE, size), 0);
+               size -= min_t(size_t, PAGE_SIZE, size);
+       }
+       return buf;
+
+userptr_fail_get_user_pages:
+       printk(KERN_DEBUG "get_user_pages requested/got: %d/%d]\n",
+              num_pages_from_user, buf->sg_desc.num_pages);
+       while (--num_pages_from_user >= 0)
+               put_page(buf->pages[num_pages_from_user]);
+
+userptr_fail_pages_array_alloc:
+       vfree(buf->sg_desc.sglist);
+
+userptr_fail_sglist_alloc:
+       kfree(buf);
+       return NULL;
+}
+
+/*
+ * @put_userptr: inform the allocator that a USERPTR buffer will no longer
+ *              be used
+ */
+static void vb2_dma_sg_put_userptr(void *buf_priv)
+{
+       struct vb2_dma_sg_buf *buf = buf_priv;
+       int i = buf->sg_desc.num_pages;
+
+       printk(KERN_DEBUG "%s: Releasing userspace buffer of %d pages\n",
+              __func__, buf->sg_desc.num_pages);
+       if (buf->vaddr)
+               vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
+       while (--i >= 0) {
+               if (buf->write)
+                       set_page_dirty_lock(buf->pages[i]);
+               put_page(buf->pages[i]);
+       }
+       vfree(buf->sg_desc.sglist);
+       kfree(buf->pages);
+       kfree(buf);
+}
+
+static void *vb2_dma_sg_vaddr(void *buf_priv)
+{
+       struct vb2_dma_sg_buf *buf = buf_priv;
+
+       BUG_ON(!buf);
+
+       if (!buf->vaddr)
+               buf->vaddr = vm_map_ram(buf->pages,
+                                       buf->sg_desc.num_pages,
+                                       -1,
+                                       PAGE_KERNEL);
+
+       /* add offset in case userptr is not page-aligned */
+       return buf->vaddr + buf->offset;
+}
+
+static unsigned int vb2_dma_sg_num_users(void *buf_priv)
+{
+       struct vb2_dma_sg_buf *buf = buf_priv;
+
+       return atomic_read(&buf->refcount);
+}
+
+static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
+{
+       struct vb2_dma_sg_buf *buf = buf_priv;
+       unsigned long uaddr = vma->vm_start;
+       unsigned long usize = vma->vm_end - vma->vm_start;
+       int i = 0;
+
+       if (!buf) {
+               printk(KERN_ERR "No memory to map\n");
+               return -EINVAL;
+       }
+
+       do {
+               int ret;
+
+               ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
+               if (ret) {
+                       printk(KERN_ERR "Remapping memory, error: %d\n", ret);
+                       return ret;
+               }
+
+               uaddr += PAGE_SIZE;
+               usize -= PAGE_SIZE;
+       } while (usize > 0);
+
+
+       /*
+        * Use common vm_area operations to track buffer refcount.
+        */
+       vma->vm_private_data    = &buf->handler;
+       vma->vm_ops             = &vb2_common_vm_ops;
+
+       vma->vm_ops->open(vma);
+
+       return 0;
+}
+
+static void *vb2_dma_sg_cookie(void *buf_priv)
+{
+       struct vb2_dma_sg_buf *buf = buf_priv;
+
+       return &buf->sg_desc;
+}
+
+const struct vb2_mem_ops vb2_dma_sg_memops = {
+       .alloc          = vb2_dma_sg_alloc,
+       .put            = vb2_dma_sg_put,
+       .get_userptr    = vb2_dma_sg_get_userptr,
+       .put_userptr    = vb2_dma_sg_put_userptr,
+       .vaddr          = vb2_dma_sg_vaddr,
+       .mmap           = vb2_dma_sg_mmap,
+       .num_users      = vb2_dma_sg_num_users,
+       .cookie         = vb2_dma_sg_cookie,
+};
+EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
+
+MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
+MODULE_AUTHOR("Andrzej Pietrasiewicz");
+MODULE_LICENSE("GPL");
diff --git a/include/media/videobuf2-dma-sg.h b/include/media/videobuf2-dma-sg.h
new file mode 100644 (file)
index 0000000..0038526
--- /dev/null
@@ -0,0 +1,32 @@
+/*
+ * videobuf2-dma-sg.h - DMA scatter/gather memory allocator for videobuf2
+ *
+ * Copyright (C) 2010 Samsung Electronics
+ *
+ * Author: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
+ *
+ * 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.
+ */
+
+#ifndef _MEDIA_VIDEOBUF2_DMA_SG_H
+#define _MEDIA_VIDEOBUF2_DMA_SG_H
+
+#include <media/videobuf2-core.h>
+
+struct vb2_dma_sg_desc {
+       unsigned long           size;
+       unsigned int            num_pages;
+       struct scatterlist      *sglist;
+};
+
+static inline struct vb2_dma_sg_desc *vb2_dma_sg_plane_desc(
+               struct vb2_buffer *vb, unsigned int plane_no)
+{
+       return (struct vb2_dma_sg_desc *)vb2_plane_cookie(vb, plane_no);
+}
+
+extern const struct vb2_mem_ops vb2_dma_sg_memops;
+
+#endif