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 sg_table sg_table;
40 unsigned int num_pages;
42 struct vb2_vmarea_handler handler;
45 static void vb2_dma_sg_put(void *buf_priv);
47 static int vb2_dma_sg_alloc_compacted(struct vb2_dma_sg_buf *buf,
50 unsigned int last_page = 0;
58 order = get_order(size);
59 /* Dont over allocate*/
60 if ((PAGE_SIZE << order) > size)
65 pages = alloc_pages(GFP_KERNEL | __GFP_ZERO |
66 __GFP_NOWARN | gfp_flags, order);
72 __free_page(buf->pages[last_page]);
78 split_page(pages, order);
79 for (i = 0; i < (1 << order); i++)
80 buf->pages[last_page++] = &pages[i];
82 size -= PAGE_SIZE << order;
88 static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_flags)
90 struct vb2_dma_sg_buf *buf;
94 buf = kzalloc(sizeof *buf, GFP_KERNEL);
102 /* size is already page aligned */
103 buf->num_pages = size >> PAGE_SHIFT;
105 buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
108 goto fail_pages_array_alloc;
110 ret = vb2_dma_sg_alloc_compacted(buf, gfp_flags);
112 goto fail_pages_alloc;
114 ret = sg_alloc_table_from_pages(&buf->sg_table, buf->pages,
115 buf->num_pages, 0, size, gfp_flags);
117 goto fail_table_alloc;
119 buf->handler.refcount = &buf->refcount;
120 buf->handler.put = vb2_dma_sg_put;
121 buf->handler.arg = buf;
123 atomic_inc(&buf->refcount);
125 dprintk(1, "%s: Allocated buffer of %d pages\n",
126 __func__, buf->num_pages);
130 num_pages = buf->num_pages;
132 __free_page(buf->pages[num_pages]);
135 fail_pages_array_alloc:
140 static void vb2_dma_sg_put(void *buf_priv)
142 struct vb2_dma_sg_buf *buf = buf_priv;
143 int i = buf->num_pages;
145 if (atomic_dec_and_test(&buf->refcount)) {
146 dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
149 vm_unmap_ram(buf->vaddr, buf->num_pages);
150 sg_free_table(&buf->sg_table);
152 __free_page(buf->pages[i]);
158 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
159 unsigned long size, int write)
161 struct vb2_dma_sg_buf *buf;
162 unsigned long first, last;
163 int num_pages_from_user;
165 buf = kzalloc(sizeof *buf, GFP_KERNEL);
171 buf->offset = vaddr & ~PAGE_MASK;
174 first = (vaddr & PAGE_MASK) >> PAGE_SHIFT;
175 last = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
176 buf->num_pages = last - first + 1;
178 buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
181 goto userptr_fail_alloc_pages;
183 num_pages_from_user = get_user_pages(current, current->mm,
191 if (num_pages_from_user != buf->num_pages)
192 goto userptr_fail_get_user_pages;
194 if (sg_alloc_table_from_pages(&buf->sg_table, buf->pages,
195 buf->num_pages, buf->offset, size, 0))
196 goto userptr_fail_alloc_table_from_pages;
200 userptr_fail_alloc_table_from_pages:
201 userptr_fail_get_user_pages:
202 dprintk(1, "get_user_pages requested/got: %d/%d]\n",
203 num_pages_from_user, buf->num_pages);
204 while (--num_pages_from_user >= 0)
205 put_page(buf->pages[num_pages_from_user]);
207 userptr_fail_alloc_pages:
213 * @put_userptr: inform the allocator that a USERPTR buffer will no longer
216 static void vb2_dma_sg_put_userptr(void *buf_priv)
218 struct vb2_dma_sg_buf *buf = buf_priv;
219 int i = buf->num_pages;
221 dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
222 __func__, buf->num_pages);
224 vm_unmap_ram(buf->vaddr, buf->num_pages);
225 sg_free_table(&buf->sg_table);
228 set_page_dirty_lock(buf->pages[i]);
229 put_page(buf->pages[i]);
235 static void *vb2_dma_sg_vaddr(void *buf_priv)
237 struct vb2_dma_sg_buf *buf = buf_priv;
242 buf->vaddr = vm_map_ram(buf->pages,
247 /* add offset in case userptr is not page-aligned */
248 return buf->vaddr + buf->offset;
251 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
253 struct vb2_dma_sg_buf *buf = buf_priv;
255 return atomic_read(&buf->refcount);
258 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
260 struct vb2_dma_sg_buf *buf = buf_priv;
261 unsigned long uaddr = vma->vm_start;
262 unsigned long usize = vma->vm_end - vma->vm_start;
266 printk(KERN_ERR "No memory to map\n");
273 ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
275 printk(KERN_ERR "Remapping memory, error: %d\n", ret);
285 * Use common vm_area operations to track buffer refcount.
287 vma->vm_private_data = &buf->handler;
288 vma->vm_ops = &vb2_common_vm_ops;
290 vma->vm_ops->open(vma);
295 static void *vb2_dma_sg_cookie(void *buf_priv)
297 struct vb2_dma_sg_buf *buf = buf_priv;
299 return &buf->sg_table;
302 const struct vb2_mem_ops vb2_dma_sg_memops = {
303 .alloc = vb2_dma_sg_alloc,
304 .put = vb2_dma_sg_put,
305 .get_userptr = vb2_dma_sg_get_userptr,
306 .put_userptr = vb2_dma_sg_put_userptr,
307 .vaddr = vb2_dma_sg_vaddr,
308 .mmap = vb2_dma_sg_mmap,
309 .num_users = vb2_dma_sg_num_users,
310 .cookie = vb2_dma_sg_cookie,
312 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
314 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
315 MODULE_AUTHOR("Andrzej Pietrasiewicz");
316 MODULE_LICENSE("GPL");