linux/sound/core/sgbuf.c
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   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
  32int 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
  66void *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
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