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 <asm/pgtable.h>
  27 #include <sound/memalloc.h>
  28
  29
  30 /* table entries are align to 32 */
  31 #define SGBUF_TBL_ALIGN         32
  32 #define sgbuf_align_table(tbl)  ALIGN((tbl), SGBUF_TBL_ALIGN)
  33
  34 int snd_free_sgbuf_pages(struct snd_dma_buffer *dmab)
  35 {
  36         struct snd_sg_buf *sgbuf = dmab->private_data;
  37         struct snd_dma_buffer tmpb;
  38         int i;
  39
  40         if (! sgbuf)
  41                 return -EINVAL;
  42
  43         vunmap(dmab->area);
  44         dmab->area = NULL;
  45
  46         tmpb.dev.type = SNDRV_DMA_TYPE_DEV;
  47         if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_UC_SG)
  48                 tmpb.dev.type = SNDRV_DMA_TYPE_DEV_UC;
  49         tmpb.dev.dev = sgbuf->dev;
  50         for (i = 0; i < sgbuf->pages; i++) {
  51                 if (!(sgbuf->table[i].addr & ~PAGE_MASK))
  52                         continue; /* continuous pages */
  53                 tmpb.area = sgbuf->table[i].buf;
  54                 tmpb.addr = sgbuf->table[i].addr & PAGE_MASK;
  55                 tmpb.bytes = (sgbuf->table[i].addr & ~PAGE_MASK) << PAGE_SHIFT;
  56                 snd_dma_free_pages(&tmpb);
  57         }
  58
  59         kfree(sgbuf->table);
  60         kfree(sgbuf->page_table);
  61         kfree(sgbuf);
  62         dmab->private_data = NULL;
  63
  64         return 0;
  65 }
  66
  67 #define MAX_ALLOC_PAGES         32
  68
  69 void *snd_malloc_sgbuf_pages(struct device *device,
  70                              size_t size, struct snd_dma_buffer *dmab,
  71                              size_t *res_size)
  72 {
  73         struct snd_sg_buf *sgbuf;
  74         unsigned int i, pages, chunk, maxpages;
  75         struct snd_dma_buffer tmpb;
  76         struct snd_sg_page *table;
  77         struct page **pgtable;
  78         int type = SNDRV_DMA_TYPE_DEV;
  79         pgprot_t prot = PAGE_KERNEL;
  80
  81         dmab->area = NULL;
  82         dmab->addr = 0;
  83         dmab->private_data = sgbuf = kzalloc(sizeof(*sgbuf), GFP_KERNEL);
  84         if (! sgbuf)
  85                 return NULL;
  86         if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_UC_SG) {
  87                 type = SNDRV_DMA_TYPE_DEV_UC;
  88 #ifdef pgprot_noncached
  89                 prot = pgprot_noncached(PAGE_KERNEL);
  90 #endif
  91         }
  92         sgbuf->dev = device;
  93         pages = snd_sgbuf_aligned_pages(size);
  94         sgbuf->tblsize = sgbuf_align_table(pages);
  95         table = kcalloc(sgbuf->tblsize, sizeof(*table), GFP_KERNEL);
  96         if (!table)
  97                 goto _failed;
  98         sgbuf->table = table;
  99         pgtable = kcalloc(sgbuf->tblsize, sizeof(*pgtable), GFP_KERNEL);
 100         if (!pgtable)
 101                 goto _failed;
 102         sgbuf->page_table = pgtable;
 103
 104         /* allocate pages */
 105         maxpages = MAX_ALLOC_PAGES;
 106         while (pages > 0) {
 107                 chunk = pages;
 108                 /* don't be too eager to take a huge chunk */
 109                 if (chunk > maxpages)
 110                         chunk = maxpages;
 111                 chunk <<= PAGE_SHIFT;
 112                 if (snd_dma_alloc_pages_fallback(type, device,
 113                                                  chunk, &tmpb) < 0) {
 114                         if (!sgbuf->pages)
 115                                 goto _failed;
 116                         if (!res_size)
 117                                 goto _failed;
 118                         size = sgbuf->pages * PAGE_SIZE;
 119                         break;
 120                 }
 121                 chunk = tmpb.bytes >> PAGE_SHIFT;
 122                 for (i = 0; i < chunk; i++) {
 123                         table->buf = tmpb.area;
 124                         table->addr = tmpb.addr;
 125                         if (!i)
 126                                 table->addr |= chunk; /* mark head */
 127                         table++;
 128                         *pgtable++ = virt_to_page(tmpb.area);
 129                         tmpb.area += PAGE_SIZE;
 130                         tmpb.addr += PAGE_SIZE;
 131                 }
 132                 sgbuf->pages += chunk;
 133                 pages -= chunk;
 134                 if (chunk < maxpages)
 135                         maxpages = chunk;
 136         }
 137
 138         sgbuf->size = size;
 139         dmab->area = vmap(sgbuf->page_table, sgbuf->pages, VM_MAP, prot);
 140         if (! dmab->area)
 141                 goto _failed;
 142         if (res_size)
 143                 *res_size = sgbuf->size;
 144         return dmab->area;
 145
 146  _failed:
 147         snd_free_sgbuf_pages(dmab); /* free the table */
 148         return NULL;
 149 }
 150
 151 /*
 152  * compute the max chunk size with continuous pages on sg-buffer
 153  */
 154 unsigned int snd_sgbuf_get_chunk_size(struct snd_dma_buffer *dmab,
 155                                       unsigned int ofs, unsigned int size)
 156 {
 157         struct snd_sg_buf *sg = dmab->private_data;
 158         unsigned int start, end, pg;
 159
 160         start = ofs >> PAGE_SHIFT;
 161         end = (ofs + size - 1) >> PAGE_SHIFT;
 162         /* check page continuity */
 163         pg = sg->table[start].addr >> PAGE_SHIFT;
 164         for (;;) {
 165                 start++;
 166                 if (start > end)
 167                         break;
 168                 pg++;
 169                 if ((sg->table[start].addr >> PAGE_SHIFT) != pg)
 170                         return (start << PAGE_SHIFT) - ofs;
 171         }
 172         /* ok, all on continuous pages */
 173         return size;
 174 }
 175 EXPORT_SYMBOL(snd_sgbuf_get_chunk_size);