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         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                                 goto _failed;
 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 }
 139
 140 /*
 141  * compute the max chunk size with continuous pages on sg-buffer
 142  */
 143 unsigned int snd_sgbuf_get_chunk_size(struct snd_dma_buffer *dmab,
 144                                       unsigned int ofs, unsigned int size)
 145 {
 146         struct snd_sg_buf *sg = dmab->private_data;
 147         unsigned int start, end, pg;
 148
 149         start = ofs >> PAGE_SHIFT;
 150         end = (ofs + size - 1) >> PAGE_SHIFT;
 151         /* check page continuity */
 152         pg = sg->table[start].addr >> PAGE_SHIFT;
 153         for (;;) {
 154                 start++;
 155                 if (start > end)
 156                         break;
 157                 pg++;
 158                 if ((sg->table[start].addr >> PAGE_SHIFT) != pg)
 159                         return (start << PAGE_SHIFT) - ofs;
 160         }
 161         /* ok, all on continuous pages */
 162         return size;
 163 }
 164 EXPORT_SYMBOL(snd_sgbuf_get_chunk_size);