ALSA: pcm: fix delta calculation at boundary wraparound
[linux-2.6.git] / sound / core / sgbuf.c
1 /*
2  * Scatter-Gather buffer
3  *
4  *  Copyright (c) by Takashi Iwai <tiwai@suse.de>
5  *
6  *   This program is free software; you can redistribute it and/or modify
7  *   it under the terms of the GNU General Public License as published by
8  *   the Free Software Foundation; either version 2 of the License, or
9  *   (at your option) any later version.
10  *
11  *   This program is distributed in the hope that it will be useful,
12  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
13  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  *   GNU General Public License for more details.
15  *
16  *   You should have received a copy of the GNU General Public License
17  *   along with this program; if not, write to the Free Software
18  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
19  *
20  */
21
22 #include <linux/slab.h>
23 #include <linux/mm.h>
24 #include <linux/vmalloc.h>
25 #include <sound/memalloc.h>
26
27
28 /* table entries are align to 32 */
29 #define SGBUF_TBL_ALIGN         32
30 #define sgbuf_align_table(tbl)  ALIGN((tbl), SGBUF_TBL_ALIGN)
31
32 int snd_free_sgbuf_pages(struct snd_dma_buffer *dmab)
33 {
34         struct snd_sg_buf *sgbuf = dmab->private_data;
35         struct snd_dma_buffer tmpb;
36         int i;
37
38         if (! sgbuf)
39                 return -EINVAL;
40
41         if (dmab->area)
42                 vunmap(dmab->area);
43         dmab->area = NULL;
44
45         tmpb.dev.type = SNDRV_DMA_TYPE_DEV;
46         tmpb.dev.dev = sgbuf->dev;
47         for (i = 0; i < sgbuf->pages; i++) {
48                 if (!(sgbuf->table[i].addr & ~PAGE_MASK))
49                         continue; /* continuous pages */
50                 tmpb.area = sgbuf->table[i].buf;
51                 tmpb.addr = sgbuf->table[i].addr & PAGE_MASK;
52                 tmpb.bytes = (sgbuf->table[i].addr & ~PAGE_MASK) << PAGE_SHIFT;
53                 snd_dma_free_pages(&tmpb);
54         }
55
56         kfree(sgbuf->table);
57         kfree(sgbuf->page_table);
58         kfree(sgbuf);
59         dmab->private_data = NULL;
60         
61         return 0;
62 }
63
64 #define MAX_ALLOC_PAGES         32
65
66 void *snd_malloc_sgbuf_pages(struct device *device,
67                              size_t size, struct snd_dma_buffer *dmab,
68                              size_t *res_size)
69 {
70         struct snd_sg_buf *sgbuf;
71         unsigned int i, pages, chunk, maxpages;
72         struct snd_dma_buffer tmpb;
73         struct snd_sg_page *table;
74         struct page **pgtable;
75
76         dmab->area = NULL;
77         dmab->addr = 0;
78         dmab->private_data = sgbuf = kzalloc(sizeof(*sgbuf), GFP_KERNEL);
79         if (! sgbuf)
80                 return NULL;
81         sgbuf->dev = device;
82         pages = snd_sgbuf_aligned_pages(size);
83         sgbuf->tblsize = sgbuf_align_table(pages);
84         table = kcalloc(sgbuf->tblsize, sizeof(*table), GFP_KERNEL);
85         if (!table)
86                 goto _failed;
87         sgbuf->table = table;
88         pgtable = kcalloc(sgbuf->tblsize, sizeof(*pgtable), GFP_KERNEL);
89         if (!pgtable)
90                 goto _failed;
91         sgbuf->page_table = pgtable;
92
93         /* allocate pages */
94         maxpages = MAX_ALLOC_PAGES;
95         while (pages > 0) {
96                 chunk = pages;
97                 /* don't be too eager to take a huge chunk */
98                 if (chunk > maxpages)
99                         chunk = maxpages;
100                 chunk <<= PAGE_SHIFT;
101                 if (snd_dma_alloc_pages_fallback(SNDRV_DMA_TYPE_DEV, device,
102                                                  chunk, &tmpb) < 0) {
103                         if (!sgbuf->pages)
104                                 return NULL;
105                         if (!res_size)
106                                 goto _failed;
107                         size = sgbuf->pages * PAGE_SIZE;
108                         break;
109                 }
110                 chunk = tmpb.bytes >> PAGE_SHIFT;
111                 for (i = 0; i < chunk; i++) {
112                         table->buf = tmpb.area;
113                         table->addr = tmpb.addr;
114                         if (!i)
115                                 table->addr |= chunk; /* mark head */
116                         table++;
117                         *pgtable++ = virt_to_page(tmpb.area);
118                         tmpb.area += PAGE_SIZE;
119                         tmpb.addr += PAGE_SIZE;
120                 }
121                 sgbuf->pages += chunk;
122                 pages -= chunk;
123                 if (chunk < maxpages)
124                         maxpages = chunk;
125         }
126
127         sgbuf->size = size;
128         dmab->area = vmap(sgbuf->page_table, sgbuf->pages, VM_MAP, PAGE_KERNEL);
129         if (! dmab->area)
130                 goto _failed;
131         if (res_size)
132                 *res_size = sgbuf->size;
133         return dmab->area;
134
135  _failed:
136         snd_free_sgbuf_pages(dmab); /* free the table */
137         return NULL;
138 }