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 <linux/export.h>
  26 #include <sound/memalloc.h>
  27
  28
  29 /* table entries are align to 32 */
  30 #define SGBUF_TBL_ALIGN         32
  31 #define sgbuf_align_table(tbl)  ALIGN((tbl), SGBUF_TBL_ALIGN)
  32
  33 int snd_free_sgbuf_pages(struct snd_dma_buffer *dmab)
  34 {
  35         struct snd_sg_buf *sgbuf = dmab->private_data;
  36         struct snd_dma_buffer tmpb;
  37         int i;
  38
  39         if (! sgbuf)
  40                 return -EINVAL;
  41
  42         if (dmab->area)
  43                 vunmap(dmab->area);
  44         dmab->area = NULL;
  45
  46         tmpb.dev.type = SNDRV_DMA_TYPE_DEV;
  47         tmpb.dev.dev = sgbuf->dev;
  48         for (i = 0; i < sgbuf->pages; i++) {
  49                 if (!(sgbuf->table[i].addr & ~PAGE_MASK))
  50                         continue; /* continuous pages */
  51                 tmpb.area = sgbuf->table[i].buf;
  52                 tmpb.addr = sgbuf->table[i].addr & PAGE_MASK;
  53                 tmpb.bytes = (sgbuf->table[i].addr & ~PAGE_MASK) << PAGE_SHIFT;
  54                 snd_dma_free_pages(&tmpb);
  55         }
  56
  57         kfree(sgbuf->table);
  58         kfree(sgbuf->page_table);
  59         kfree(sgbuf);
  60         dmab->private_data = NULL;
  61
  62         return 0;
  63 }
  64
  65 #define MAX_ALLOC_PAGES         32
  66
  67 void *snd_malloc_sgbuf_pages(struct device *device,
  68                              size_t size, struct snd_dma_buffer *dmab,
  69                              size_t *res_size)
  70 {
  71         struct snd_sg_buf *sgbuf;
  72         unsigned int i, pages, chunk, maxpages;
  73         struct snd_dma_buffer tmpb;
  74         struct snd_sg_page *table;
  75         struct page **pgtable;
  76
  77         dmab->area = NULL;
  78         dmab->addr = 0;
  79         dmab->private_data = sgbuf = kzalloc(sizeof(*sgbuf), GFP_KERNEL);
  80         if (! sgbuf)
  81                 return NULL;
  82         sgbuf->dev = device;
  83         pages = snd_sgbuf_aligned_pages(size);
  84         sgbuf->tblsize = sgbuf_align_table(pages);
  85         table = kcalloc(sgbuf->tblsize, sizeof(*table), GFP_KERNEL);
  86         if (!table)
  87                 goto _failed;
  88         sgbuf->table = table;
  89         pgtable = kcalloc(sgbuf->tblsize, sizeof(*pgtable), GFP_KERNEL);
  90         if (!pgtable)
  91                 goto _failed;
  92         sgbuf->page_table = pgtable;
  93
  94         /* allocate pages */
  95         maxpages = MAX_ALLOC_PAGES;
  96         while (pages > 0) {
  97                 chunk = pages;
  98                 /* don't be too eager to take a huge chunk */
  99                 if (chunk > maxpages)
 100                         chunk = maxpages;
 101                 chunk <<= PAGE_SHIFT;
 102                 if (snd_dma_alloc_pages_fallback(SNDRV_DMA_TYPE_DEV, device,
 103                                                  chunk, &tmpb) < 0) {
 104                         if (!sgbuf->pages)
 105                                 goto _failed;
 106                         if (!res_size)
 107                                 goto _failed;
 108                         size = sgbuf->pages * PAGE_SIZE;
 109                         break;
 110                 }
 111                 chunk = tmpb.bytes >> PAGE_SHIFT;
 112                 for (i = 0; i < chunk; i++) {
 113                         table->buf = tmpb.area;
 114                         table->addr = tmpb.addr;
 115                         if (!i)
 116                                 table->addr |= chunk; /* mark head */
 117                         table++;
 118                         *pgtable++ = virt_to_page(tmpb.area);
 119                         tmpb.area += PAGE_SIZE;
 120                         tmpb.addr += PAGE_SIZE;
 121                 }
 122                 sgbuf->pages += chunk;
 123                 pages -= chunk;
 124                 if (chunk < maxpages)
 125                         maxpages = chunk;
 126         }
 127
 128         sgbuf->size = size;
 129         dmab->area = vmap(sgbuf->page_table, sgbuf->pages, VM_MAP, PAGE_KERNEL);
 130         if (! dmab->area)
 131                 goto _failed;
 132         if (res_size)
 133                 *res_size = sgbuf->size;
 134         return dmab->area;
 135
 136  _failed:
 137         snd_free_sgbuf_pages(dmab); /* free the table */
 138         return NULL;
 139 }
 140
 141 /*
 142  * compute the max chunk size with continuous pages on sg-buffer
 143  */
 144 unsigned int snd_sgbuf_get_chunk_size(struct snd_dma_buffer *dmab,
 145                                       unsigned int ofs, unsigned int size)
 146 {
 147         struct snd_sg_buf *sg = dmab->private_data;
 148         unsigned int start, end, pg;
 149
 150         start = ofs >> PAGE_SHIFT;
 151         end = (ofs + size - 1) >> PAGE_SHIFT;
 152         /* check page continuity */
 153         pg = sg->table[start].addr >> PAGE_SHIFT;
 154         for (;;) {
 155                 start++;
 156                 if (start > end)
 157                         break;
 158                 pg++;
 159                 if ((sg->table[start].addr >> PAGE_SHIFT) != pg)
 160                         return (start << PAGE_SHIFT) - ofs;
 161         }
 162         /* ok, all on continuous pages */
 163         return size;
 164 }
 165 EXPORT_SYMBOL(snd_sgbuf_get_chunk_size);