sound/core/sgbuf.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Scatter-Gather buffer
   4  *
   5  *  Copyright (c) by Takashi Iwai <tiwai@suse.de>
   6  */
   7
   8 #include <linux/slab.h>
   9 #include <linux/mm.h>
  10 #include <linux/vmalloc.h>
  11 #include <linux/export.h>
  12 #include <sound/memalloc.h>
  13
  14
  15 /* table entries are align to 32 */
  16 #define SGBUF_TBL_ALIGN         32
  17 #define sgbuf_align_table(tbl)  ALIGN((tbl), SGBUF_TBL_ALIGN)
  18
  19 int snd_free_sgbuf_pages(struct snd_dma_buffer *dmab)
  20 {
  21         struct snd_sg_buf *sgbuf = dmab->private_data;
  22         struct snd_dma_buffer tmpb;
  23         int i;
  24
  25         if (! sgbuf)
  26                 return -EINVAL;
  27
  28         vunmap(dmab->area);
  29         dmab->area = NULL;
  30
  31         tmpb.dev.type = SNDRV_DMA_TYPE_DEV;
  32         if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_UC_SG)
  33                 tmpb.dev.type = SNDRV_DMA_TYPE_DEV_UC;
  34         tmpb.dev.dev = sgbuf->dev;
  35         for (i = 0; i < sgbuf->pages; i++) {
  36                 if (!(sgbuf->table[i].addr & ~PAGE_MASK))
  37                         continue; /* continuous pages */
  38                 tmpb.area = sgbuf->table[i].buf;
  39                 tmpb.addr = sgbuf->table[i].addr & PAGE_MASK;
  40                 tmpb.bytes = (sgbuf->table[i].addr & ~PAGE_MASK) << PAGE_SHIFT;
  41                 snd_dma_free_pages(&tmpb);
  42         }
  43
  44         kfree(sgbuf->table);
  45         kfree(sgbuf->page_table);
  46         kfree(sgbuf);
  47         dmab->private_data = NULL;
  48
  49         return 0;
  50 }
  51
  52 #define MAX_ALLOC_PAGES         32
  53
  54 void *snd_malloc_sgbuf_pages(struct device *device,
  55                              size_t size, struct snd_dma_buffer *dmab,
  56                              size_t *res_size)
  57 {
  58         struct snd_sg_buf *sgbuf;
  59         unsigned int i, pages, chunk, maxpages;
  60         struct snd_dma_buffer tmpb;
  61         struct snd_sg_page *table;
  62         struct page **pgtable;
  63         int type = SNDRV_DMA_TYPE_DEV;
  64         pgprot_t prot = PAGE_KERNEL;
  65
  66         dmab->area = NULL;
  67         dmab->addr = 0;
  68         dmab->private_data = sgbuf = kzalloc(sizeof(*sgbuf), GFP_KERNEL);
  69         if (! sgbuf)
  70                 return NULL;
  71         if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_UC_SG) {
  72                 type = SNDRV_DMA_TYPE_DEV_UC;
  73 #ifdef pgprot_noncached
  74                 prot = pgprot_noncached(PAGE_KERNEL);
  75 #endif
  76         }
  77         sgbuf->dev = device;
  78         pages = snd_sgbuf_aligned_pages(size);
  79         sgbuf->tblsize = sgbuf_align_table(pages);
  80         table = kcalloc(sgbuf->tblsize, sizeof(*table), GFP_KERNEL);
  81         if (!table)
  82                 goto _failed;
  83         sgbuf->table = table;
  84         pgtable = kcalloc(sgbuf->tblsize, sizeof(*pgtable), GFP_KERNEL);
  85         if (!pgtable)
  86                 goto _failed;
  87         sgbuf->page_table = pgtable;
  88
  89         /* allocate pages */
  90         maxpages = MAX_ALLOC_PAGES;
  91         while (pages > 0) {
  92                 chunk = pages;
  93                 /* don't be too eager to take a huge chunk */
  94                 if (chunk > maxpages)
  95                         chunk = maxpages;
  96                 chunk <<= PAGE_SHIFT;
  97                 if (snd_dma_alloc_pages_fallback(type, device,
  98                                                  chunk, &tmpb) < 0) {
  99                         if (!sgbuf->pages)
 100                                 goto _failed;
 101                         if (!res_size)
 102                                 goto _failed;
 103                         size = sgbuf->pages * PAGE_SIZE;
 104                         break;
 105                 }
 106                 chunk = tmpb.bytes >> PAGE_SHIFT;
 107                 for (i = 0; i < chunk; i++) {
 108                         table->buf = tmpb.area;
 109                         table->addr = tmpb.addr;
 110                         if (!i)
 111                                 table->addr |= chunk; /* mark head */
 112                         table++;
 113                         *pgtable++ = virt_to_page(tmpb.area);
 114                         tmpb.area += PAGE_SIZE;
 115                         tmpb.addr += PAGE_SIZE;
 116                 }
 117                 sgbuf->pages += chunk;
 118                 pages -= chunk;
 119                 if (chunk < maxpages)
 120                         maxpages = chunk;
 121         }
 122
 123         sgbuf->size = size;
 124         dmab->area = vmap(sgbuf->page_table, sgbuf->pages, VM_MAP, prot);
 125         if (! dmab->area)
 126                 goto _failed;
 127         if (res_size)
 128                 *res_size = sgbuf->size;
 129         return dmab->area;
 130
 131  _failed:
 132         snd_free_sgbuf_pages(dmab); /* free the table */
 133         return NULL;
 134 }
 135
 136 /*
 137  * compute the max chunk size with continuous pages on sg-buffer
 138  */
 139 unsigned int snd_sgbuf_get_chunk_size(struct snd_dma_buffer *dmab,
 140                                       unsigned int ofs, unsigned int size)
 141 {
 142         struct snd_sg_buf *sg = dmab->private_data;
 143         unsigned int start, end, pg;
 144
 145         if (!sg)
 146                 return size;
 147
 148         start = ofs >> PAGE_SHIFT;
 149         end = (ofs + size - 1) >> PAGE_SHIFT;
 150         /* check page continuity */
 151         pg = sg->table[start].addr >> PAGE_SHIFT;
 152         for (;;) {
 153                 start++;
 154                 if (start > end)
 155                         break;
 156                 pg++;
 157                 if ((sg->table[start].addr >> PAGE_SHIFT) != pg)
 158                         return (start << PAGE_SHIFT) - ofs;
 159         }
 160         /* ok, all on continuous pages */
 161         return size;
 162 }
 163 EXPORT_SYMBOL(snd_sgbuf_get_chunk_size);