--- /dev/null
+/*
+ * 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(¤t->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(¤t->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");
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