2 * videobuf2-dma-sg.c - dma scatter/gather memory allocator for videobuf2
4 * Copyright (C) 2010 Samsung Electronics
6 * Author: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation.
13 #include <linux/module.h>
15 #include <linux/scatterlist.h>
16 #include <linux/sched.h>
17 #include <linux/slab.h>
18 #include <linux/vmalloc.h>
20 #include <media/videobuf2-core.h>
21 #include <media/videobuf2-memops.h>
22 #include <media/videobuf2-dma-sg.h>
24 struct vb2_dma_sg_buf {
29 struct vb2_dma_sg_desc sg_desc;
31 struct vb2_vmarea_handler handler;
34 static void vb2_dma_sg_put(void *buf_priv);
36 static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size)
38 struct vb2_dma_sg_buf *buf;
41 buf = kzalloc(sizeof *buf, GFP_KERNEL);
48 buf->sg_desc.size = size;
49 buf->sg_desc.num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
51 buf->sg_desc.sglist = vzalloc(buf->sg_desc.num_pages *
52 sizeof(*buf->sg_desc.sglist));
53 if (!buf->sg_desc.sglist)
54 goto fail_sglist_alloc;
55 sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
57 buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
60 goto fail_pages_array_alloc;
62 for (i = 0; i < buf->sg_desc.num_pages; ++i) {
63 buf->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN);
64 if (NULL == buf->pages[i])
65 goto fail_pages_alloc;
66 sg_set_page(&buf->sg_desc.sglist[i],
67 buf->pages[i], PAGE_SIZE, 0);
70 buf->handler.refcount = &buf->refcount;
71 buf->handler.put = vb2_dma_sg_put;
72 buf->handler.arg = buf;
74 atomic_inc(&buf->refcount);
76 printk(KERN_DEBUG "%s: Allocated buffer of %d pages\n",
77 __func__, buf->sg_desc.num_pages);
82 __free_page(buf->pages[i]);
85 fail_pages_array_alloc:
86 vfree(buf->sg_desc.sglist);
93 static void vb2_dma_sg_put(void *buf_priv)
95 struct vb2_dma_sg_buf *buf = buf_priv;
96 int i = buf->sg_desc.num_pages;
98 if (atomic_dec_and_test(&buf->refcount)) {
99 printk(KERN_DEBUG "%s: Freeing buffer of %d pages\n", __func__,
100 buf->sg_desc.num_pages);
102 vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
103 vfree(buf->sg_desc.sglist);
105 __free_page(buf->pages[i]);
111 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
112 unsigned long size, int write)
114 struct vb2_dma_sg_buf *buf;
115 unsigned long first, last;
116 int num_pages_from_user, i;
118 buf = kzalloc(sizeof *buf, GFP_KERNEL);
124 buf->offset = vaddr & ~PAGE_MASK;
125 buf->sg_desc.size = size;
127 first = (vaddr & PAGE_MASK) >> PAGE_SHIFT;
128 last = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
129 buf->sg_desc.num_pages = last - first + 1;
131 buf->sg_desc.sglist = vzalloc(
132 buf->sg_desc.num_pages * sizeof(*buf->sg_desc.sglist));
133 if (!buf->sg_desc.sglist)
134 goto userptr_fail_sglist_alloc;
136 sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
138 buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
141 goto userptr_fail_pages_array_alloc;
143 down_read(¤t->mm->mmap_sem);
144 num_pages_from_user = get_user_pages(current, current->mm,
146 buf->sg_desc.num_pages,
151 up_read(¤t->mm->mmap_sem);
152 if (num_pages_from_user != buf->sg_desc.num_pages)
153 goto userptr_fail_get_user_pages;
155 sg_set_page(&buf->sg_desc.sglist[0], buf->pages[0],
156 PAGE_SIZE - buf->offset, buf->offset);
157 size -= PAGE_SIZE - buf->offset;
158 for (i = 1; i < buf->sg_desc.num_pages; ++i) {
159 sg_set_page(&buf->sg_desc.sglist[i], buf->pages[i],
160 min_t(size_t, PAGE_SIZE, size), 0);
161 size -= min_t(size_t, PAGE_SIZE, size);
165 userptr_fail_get_user_pages:
166 printk(KERN_DEBUG "get_user_pages requested/got: %d/%d]\n",
167 num_pages_from_user, buf->sg_desc.num_pages);
168 while (--num_pages_from_user >= 0)
169 put_page(buf->pages[num_pages_from_user]);
172 userptr_fail_pages_array_alloc:
173 vfree(buf->sg_desc.sglist);
175 userptr_fail_sglist_alloc:
181 * @put_userptr: inform the allocator that a USERPTR buffer will no longer
184 static void vb2_dma_sg_put_userptr(void *buf_priv)
186 struct vb2_dma_sg_buf *buf = buf_priv;
187 int i = buf->sg_desc.num_pages;
189 printk(KERN_DEBUG "%s: Releasing userspace buffer of %d pages\n",
190 __func__, buf->sg_desc.num_pages);
192 vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
195 set_page_dirty_lock(buf->pages[i]);
196 put_page(buf->pages[i]);
198 vfree(buf->sg_desc.sglist);
203 static void *vb2_dma_sg_vaddr(void *buf_priv)
205 struct vb2_dma_sg_buf *buf = buf_priv;
210 buf->vaddr = vm_map_ram(buf->pages,
211 buf->sg_desc.num_pages,
215 /* add offset in case userptr is not page-aligned */
216 return buf->vaddr + buf->offset;
219 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
221 struct vb2_dma_sg_buf *buf = buf_priv;
223 return atomic_read(&buf->refcount);
226 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
228 struct vb2_dma_sg_buf *buf = buf_priv;
229 unsigned long uaddr = vma->vm_start;
230 unsigned long usize = vma->vm_end - vma->vm_start;
234 printk(KERN_ERR "No memory to map\n");
241 ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
243 printk(KERN_ERR "Remapping memory, error: %d\n", ret);
253 * Use common vm_area operations to track buffer refcount.
255 vma->vm_private_data = &buf->handler;
256 vma->vm_ops = &vb2_common_vm_ops;
258 vma->vm_ops->open(vma);
263 static void *vb2_dma_sg_cookie(void *buf_priv)
265 struct vb2_dma_sg_buf *buf = buf_priv;
267 return &buf->sg_desc;
270 const struct vb2_mem_ops vb2_dma_sg_memops = {
271 .alloc = vb2_dma_sg_alloc,
272 .put = vb2_dma_sg_put,
273 .get_userptr = vb2_dma_sg_get_userptr,
274 .put_userptr = vb2_dma_sg_put_userptr,
275 .vaddr = vb2_dma_sg_vaddr,
276 .mmap = vb2_dma_sg_mmap,
277 .num_users = vb2_dma_sg_num_users,
278 .cookie = vb2_dma_sg_cookie,
280 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
282 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
283 MODULE_AUTHOR("Andrzej Pietrasiewicz");
284 MODULE_LICENSE("GPL");