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>
25 module_param(debug, int, 0644);
27 #define dprintk(level, fmt, arg...) \
30 printk(KERN_DEBUG "vb2-dma-sg: " fmt, ## arg); \
33 struct vb2_dma_sg_buf {
38 struct vb2_dma_sg_desc sg_desc;
40 struct vb2_vmarea_handler handler;
43 static void vb2_dma_sg_put(void *buf_priv);
45 static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_flags)
47 struct vb2_dma_sg_buf *buf;
50 buf = kzalloc(sizeof *buf, GFP_KERNEL);
57 buf->sg_desc.size = size;
58 /* size is already page aligned */
59 buf->sg_desc.num_pages = size >> PAGE_SHIFT;
61 buf->sg_desc.sglist = vzalloc(buf->sg_desc.num_pages *
62 sizeof(*buf->sg_desc.sglist));
63 if (!buf->sg_desc.sglist)
64 goto fail_sglist_alloc;
65 sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
67 buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
70 goto fail_pages_array_alloc;
72 for (i = 0; i < buf->sg_desc.num_pages; ++i) {
73 buf->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO |
74 __GFP_NOWARN | gfp_flags);
75 if (NULL == buf->pages[i])
76 goto fail_pages_alloc;
77 sg_set_page(&buf->sg_desc.sglist[i],
78 buf->pages[i], PAGE_SIZE, 0);
81 buf->handler.refcount = &buf->refcount;
82 buf->handler.put = vb2_dma_sg_put;
83 buf->handler.arg = buf;
85 atomic_inc(&buf->refcount);
87 dprintk(1, "%s: Allocated buffer of %d pages\n",
88 __func__, buf->sg_desc.num_pages);
93 __free_page(buf->pages[i]);
96 fail_pages_array_alloc:
97 vfree(buf->sg_desc.sglist);
104 static void vb2_dma_sg_put(void *buf_priv)
106 struct vb2_dma_sg_buf *buf = buf_priv;
107 int i = buf->sg_desc.num_pages;
109 if (atomic_dec_and_test(&buf->refcount)) {
110 dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
111 buf->sg_desc.num_pages);
113 vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
114 vfree(buf->sg_desc.sglist);
116 __free_page(buf->pages[i]);
122 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
123 unsigned long size, int write)
125 struct vb2_dma_sg_buf *buf;
126 unsigned long first, last;
127 int num_pages_from_user, i;
129 buf = kzalloc(sizeof *buf, GFP_KERNEL);
135 buf->offset = vaddr & ~PAGE_MASK;
136 buf->sg_desc.size = size;
138 first = (vaddr & PAGE_MASK) >> PAGE_SHIFT;
139 last = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
140 buf->sg_desc.num_pages = last - first + 1;
142 buf->sg_desc.sglist = vzalloc(
143 buf->sg_desc.num_pages * sizeof(*buf->sg_desc.sglist));
144 if (!buf->sg_desc.sglist)
145 goto userptr_fail_sglist_alloc;
147 sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
149 buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
152 goto userptr_fail_pages_array_alloc;
154 num_pages_from_user = get_user_pages(current, current->mm,
156 buf->sg_desc.num_pages,
162 if (num_pages_from_user != buf->sg_desc.num_pages)
163 goto userptr_fail_get_user_pages;
165 sg_set_page(&buf->sg_desc.sglist[0], buf->pages[0],
166 PAGE_SIZE - buf->offset, buf->offset);
167 size -= PAGE_SIZE - buf->offset;
168 for (i = 1; i < buf->sg_desc.num_pages; ++i) {
169 sg_set_page(&buf->sg_desc.sglist[i], buf->pages[i],
170 min_t(size_t, PAGE_SIZE, size), 0);
171 size -= min_t(size_t, PAGE_SIZE, size);
175 userptr_fail_get_user_pages:
176 dprintk(1, "get_user_pages requested/got: %d/%d]\n",
177 num_pages_from_user, buf->sg_desc.num_pages);
178 while (--num_pages_from_user >= 0)
179 put_page(buf->pages[num_pages_from_user]);
182 userptr_fail_pages_array_alloc:
183 vfree(buf->sg_desc.sglist);
185 userptr_fail_sglist_alloc:
191 * @put_userptr: inform the allocator that a USERPTR buffer will no longer
194 static void vb2_dma_sg_put_userptr(void *buf_priv)
196 struct vb2_dma_sg_buf *buf = buf_priv;
197 int i = buf->sg_desc.num_pages;
199 dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
200 __func__, buf->sg_desc.num_pages);
202 vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
205 set_page_dirty_lock(buf->pages[i]);
206 put_page(buf->pages[i]);
208 vfree(buf->sg_desc.sglist);
213 static void *vb2_dma_sg_vaddr(void *buf_priv)
215 struct vb2_dma_sg_buf *buf = buf_priv;
220 buf->vaddr = vm_map_ram(buf->pages,
221 buf->sg_desc.num_pages,
225 /* add offset in case userptr is not page-aligned */
226 return buf->vaddr + buf->offset;
229 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
231 struct vb2_dma_sg_buf *buf = buf_priv;
233 return atomic_read(&buf->refcount);
236 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
238 struct vb2_dma_sg_buf *buf = buf_priv;
239 unsigned long uaddr = vma->vm_start;
240 unsigned long usize = vma->vm_end - vma->vm_start;
244 printk(KERN_ERR "No memory to map\n");
251 ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
253 printk(KERN_ERR "Remapping memory, error: %d\n", ret);
263 * Use common vm_area operations to track buffer refcount.
265 vma->vm_private_data = &buf->handler;
266 vma->vm_ops = &vb2_common_vm_ops;
268 vma->vm_ops->open(vma);
273 static void *vb2_dma_sg_cookie(void *buf_priv)
275 struct vb2_dma_sg_buf *buf = buf_priv;
277 return &buf->sg_desc;
280 const struct vb2_mem_ops vb2_dma_sg_memops = {
281 .alloc = vb2_dma_sg_alloc,
282 .put = vb2_dma_sg_put,
283 .get_userptr = vb2_dma_sg_get_userptr,
284 .put_userptr = vb2_dma_sg_put_userptr,
285 .vaddr = vb2_dma_sg_vaddr,
286 .mmap = vb2_dma_sg_mmap,
287 .num_users = vb2_dma_sg_num_users,
288 .cookie = vb2_dma_sg_cookie,
290 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
292 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
293 MODULE_AUTHOR("Andrzej Pietrasiewicz");
294 MODULE_LICENSE("GPL");