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;
43 struct vm_area_struct *vma;
46 static void vb2_dma_sg_put(void *buf_priv);
48 static int vb2_dma_sg_alloc_compacted(struct vb2_dma_sg_buf *buf,
51 unsigned int last_page = 0;
59 order = get_order(size);
60 /* Dont over allocate*/
61 if ((PAGE_SIZE << order) > size)
66 pages = alloc_pages(GFP_KERNEL | __GFP_ZERO |
67 __GFP_NOWARN | gfp_flags, order);
73 __free_page(buf->pages[last_page]);
79 split_page(pages, order);
80 for (i = 0; i < (1 << order); i++)
81 buf->pages[last_page++] = &pages[i];
83 size -= PAGE_SIZE << order;
89 static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_flags)
91 struct vb2_dma_sg_buf *buf;
95 buf = kzalloc(sizeof *buf, GFP_KERNEL);
103 /* size is already page aligned */
104 buf->num_pages = size >> PAGE_SHIFT;
106 buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
109 goto fail_pages_array_alloc;
111 ret = vb2_dma_sg_alloc_compacted(buf, gfp_flags);
113 goto fail_pages_alloc;
115 ret = sg_alloc_table_from_pages(&buf->sg_table, buf->pages,
116 buf->num_pages, 0, size, gfp_flags);
118 goto fail_table_alloc;
120 buf->handler.refcount = &buf->refcount;
121 buf->handler.put = vb2_dma_sg_put;
122 buf->handler.arg = buf;
124 atomic_inc(&buf->refcount);
126 dprintk(1, "%s: Allocated buffer of %d pages\n",
127 __func__, buf->num_pages);
131 num_pages = buf->num_pages;
133 __free_page(buf->pages[num_pages]);
136 fail_pages_array_alloc:
141 static void vb2_dma_sg_put(void *buf_priv)
143 struct vb2_dma_sg_buf *buf = buf_priv;
144 int i = buf->num_pages;
146 if (atomic_dec_and_test(&buf->refcount)) {
147 dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
150 vm_unmap_ram(buf->vaddr, buf->num_pages);
151 sg_free_table(&buf->sg_table);
153 __free_page(buf->pages[i]);
159 static inline int vma_is_io(struct vm_area_struct *vma)
161 return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
164 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
165 unsigned long size, int write)
167 struct vb2_dma_sg_buf *buf;
168 unsigned long first, last;
169 int num_pages_from_user;
170 struct vm_area_struct *vma;
172 buf = kzalloc(sizeof *buf, GFP_KERNEL);
178 buf->offset = vaddr & ~PAGE_MASK;
181 first = (vaddr & PAGE_MASK) >> PAGE_SHIFT;
182 last = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
183 buf->num_pages = last - first + 1;
185 buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
188 goto userptr_fail_alloc_pages;
190 vma = find_vma(current->mm, vaddr);
192 dprintk(1, "no vma for address %lu\n", vaddr);
193 goto userptr_fail_find_vma;
196 if (vma->vm_end < vaddr + size) {
197 dprintk(1, "vma at %lu is too small for %lu bytes\n",
199 goto userptr_fail_find_vma;
202 buf->vma = vb2_get_vma(vma);
204 dprintk(1, "failed to copy vma\n");
205 goto userptr_fail_find_vma;
208 if (vma_is_io(buf->vma)) {
209 for (num_pages_from_user = 0;
210 num_pages_from_user < buf->num_pages;
211 ++num_pages_from_user, vaddr += PAGE_SIZE) {
214 if (follow_pfn(vma, vaddr, &pfn)) {
215 dprintk(1, "no page for address %lu\n", vaddr);
218 buf->pages[num_pages_from_user] = pfn_to_page(pfn);
221 num_pages_from_user = get_user_pages(current, current->mm,
229 if (num_pages_from_user != buf->num_pages)
230 goto userptr_fail_get_user_pages;
232 if (sg_alloc_table_from_pages(&buf->sg_table, buf->pages,
233 buf->num_pages, buf->offset, size, 0))
234 goto userptr_fail_alloc_table_from_pages;
238 userptr_fail_alloc_table_from_pages:
239 userptr_fail_get_user_pages:
240 dprintk(1, "get_user_pages requested/got: %d/%d]\n",
241 buf->num_pages, num_pages_from_user);
242 if (!vma_is_io(buf->vma))
243 while (--num_pages_from_user >= 0)
244 put_page(buf->pages[num_pages_from_user]);
245 vb2_put_vma(buf->vma);
246 userptr_fail_find_vma:
248 userptr_fail_alloc_pages:
254 * @put_userptr: inform the allocator that a USERPTR buffer will no longer
257 static void vb2_dma_sg_put_userptr(void *buf_priv)
259 struct vb2_dma_sg_buf *buf = buf_priv;
260 int i = buf->num_pages;
262 dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
263 __func__, buf->num_pages);
265 vm_unmap_ram(buf->vaddr, buf->num_pages);
266 sg_free_table(&buf->sg_table);
269 set_page_dirty_lock(buf->pages[i]);
270 if (!vma_is_io(buf->vma))
271 put_page(buf->pages[i]);
274 vb2_put_vma(buf->vma);
278 static void *vb2_dma_sg_vaddr(void *buf_priv)
280 struct vb2_dma_sg_buf *buf = buf_priv;
285 buf->vaddr = vm_map_ram(buf->pages,
290 /* add offset in case userptr is not page-aligned */
291 return buf->vaddr + buf->offset;
294 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
296 struct vb2_dma_sg_buf *buf = buf_priv;
298 return atomic_read(&buf->refcount);
301 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
303 struct vb2_dma_sg_buf *buf = buf_priv;
304 unsigned long uaddr = vma->vm_start;
305 unsigned long usize = vma->vm_end - vma->vm_start;
309 printk(KERN_ERR "No memory to map\n");
316 ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
318 printk(KERN_ERR "Remapping memory, error: %d\n", ret);
328 * Use common vm_area operations to track buffer refcount.
330 vma->vm_private_data = &buf->handler;
331 vma->vm_ops = &vb2_common_vm_ops;
333 vma->vm_ops->open(vma);
338 static void *vb2_dma_sg_cookie(void *buf_priv)
340 struct vb2_dma_sg_buf *buf = buf_priv;
342 return &buf->sg_table;
345 const struct vb2_mem_ops vb2_dma_sg_memops = {
346 .alloc = vb2_dma_sg_alloc,
347 .put = vb2_dma_sg_put,
348 .get_userptr = vb2_dma_sg_get_userptr,
349 .put_userptr = vb2_dma_sg_put_userptr,
350 .vaddr = vb2_dma_sg_vaddr,
351 .mmap = vb2_dma_sg_mmap,
352 .num_users = vb2_dma_sg_num_users,
353 .cookie = vb2_dma_sg_cookie,
355 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
357 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
358 MODULE_AUTHOR("Andrzej Pietrasiewicz");
359 MODULE_LICENSE("GPL");