root/sound/core/sgbuf.c

DEFINITIONS

1. snd_free_sgbuf_pages
2. snd_malloc_sgbuf_pages
3. snd_sgbuf_get_chunk_size

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