3 files changed, 299 insertions, 0 deletions

diff --git a/drivers/media/video/Kconfig b/drivers/media/video/Kconfig
index b64183e06348..8710d90f9e16 100644
--- a/drivers/media/video/Kconfig
+++ b/drivers/media/video/Kconfig
@@ -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
 #
diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
index 106d40bbe724..40833fec34dc 100644
--- a/drivers/media/video/Makefile
+++ b/drivers/media/video/Makefile
@@ -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
index 000000000000..20b5c5dcc0ef
--- /dev/null
+++ b/drivers/media/video/videobuf2-dma-sg.c
@@ -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");