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 #include "memalloc_local.h"
  14
  15 struct snd_sg_page {
  16         void *buf;
  17         dma_addr_t addr;
  18 };
  19
  20 struct snd_sg_buf {
  21         int size;       /* allocated byte size */
  22         int pages;      /* allocated pages */
  23         int tblsize;    /* allocated table size */
  24         struct snd_sg_page *table;      /* address table */
  25         struct page **page_table;       /* page table (for vmap/vunmap) */
  26         struct device *dev;
  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 static void snd_dma_sg_free(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;
  41
  42         vunmap(dmab->area);
  43         dmab->area = NULL;
  44
  45         tmpb.dev.type = SNDRV_DMA_TYPE_DEV;
  46         if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_UC_SG)
  47                 tmpb.dev.type = SNDRV_DMA_TYPE_DEV_UC;
  48         tmpb.dev.dev = sgbuf->dev;
  49         for (i = 0; i < sgbuf->pages; i++) {
  50                 if (!(sgbuf->table[i].addr & ~PAGE_MASK))
  51                         continue; /* continuous pages */
  52                 tmpb.area = sgbuf->table[i].buf;
  53                 tmpb.addr = sgbuf->table[i].addr & PAGE_MASK;
  54                 tmpb.bytes = (sgbuf->table[i].addr & ~PAGE_MASK) << PAGE_SHIFT;
  55                 snd_dma_free_pages(&tmpb);
  56         }
  57
  58         kfree(sgbuf->table);
  59         kfree(sgbuf->page_table);
  60         kfree(sgbuf);
  61         dmab->private_data = NULL;
  62 }
  63
  64 #define MAX_ALLOC_PAGES         32
  65
  66 static int snd_dma_sg_alloc(struct snd_dma_buffer *dmab, size_t size)
  67 {
  68         struct snd_sg_buf *sgbuf;
  69         unsigned int i, pages, chunk, maxpages;
  70         struct snd_dma_buffer tmpb;
  71         struct snd_sg_page *table;
  72         struct page **pgtable;
  73         int type = SNDRV_DMA_TYPE_DEV;
  74         pgprot_t prot = PAGE_KERNEL;
  75
  76         dmab->private_data = sgbuf = kzalloc(sizeof(*sgbuf), GFP_KERNEL);
  77         if (!sgbuf)
  78                 return -ENOMEM;
  79         if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_UC_SG) {
  80                 type = SNDRV_DMA_TYPE_DEV_UC;
  81 #ifdef pgprot_noncached
  82                 prot = pgprot_noncached(PAGE_KERNEL);
  83 #endif
  84         }
  85         sgbuf->dev = dmab->dev.dev;
  86         pages = snd_sgbuf_aligned_pages(size);
  87         sgbuf->tblsize = sgbuf_align_table(pages);
  88         table = kcalloc(sgbuf->tblsize, sizeof(*table), GFP_KERNEL);
  89         if (!table)
  90                 goto _failed;
  91         sgbuf->table = table;
  92         pgtable = kcalloc(sgbuf->tblsize, sizeof(*pgtable), GFP_KERNEL);
  93         if (!pgtable)
  94                 goto _failed;
  95         sgbuf->page_table = pgtable;
  96
  97         /* allocate pages */
  98         maxpages = MAX_ALLOC_PAGES;
  99         while (pages > 0) {
 100                 chunk = pages;
 101                 /* don't be too eager to take a huge chunk */
 102                 if (chunk > maxpages)
 103                         chunk = maxpages;
 104                 chunk <<= PAGE_SHIFT;
 105                 if (snd_dma_alloc_pages_fallback(type, dmab->dev.dev,
 106                                                  chunk, &tmpb) < 0) {
 107                         if (!sgbuf->pages)
 108                                 goto _failed;
 109                         size = sgbuf->pages * PAGE_SIZE;
 110                         break;
 111                 }
 112                 chunk = tmpb.bytes >> PAGE_SHIFT;
 113                 for (i = 0; i < chunk; i++) {
 114                         table->buf = tmpb.area;
 115                         table->addr = tmpb.addr;
 116                         if (!i)
 117                                 table->addr |= chunk; /* mark head */
 118                         table++;
 119                         *pgtable++ = virt_to_page(tmpb.area);
 120                         tmpb.area += PAGE_SIZE;
 121                         tmpb.addr += PAGE_SIZE;
 122                 }
 123                 sgbuf->pages += chunk;
 124                 pages -= chunk;
 125                 if (chunk < maxpages)
 126                         maxpages = chunk;
 127         }
 128
 129         sgbuf->size = size;
 130         dmab->area = vmap(sgbuf->page_table, sgbuf->pages, VM_MAP, prot);
 131         if (! dmab->area)
 132                 goto _failed;
 133         return 0;
 134
 135  _failed:
 136         snd_dma_sg_free(dmab); /* free the table */
 137         return -ENOMEM;
 138 }
 139
 140 static dma_addr_t snd_dma_sg_get_addr(struct snd_dma_buffer *dmab,
 141                                       size_t offset)
 142 {
 143         struct snd_sg_buf *sgbuf = dmab->private_data;
 144         dma_addr_t addr;
 145
 146         addr = sgbuf->table[offset >> PAGE_SHIFT].addr;
 147         addr &= ~((dma_addr_t)PAGE_SIZE - 1);
 148         return addr + offset % PAGE_SIZE;
 149 }
 150
 151 static struct page *snd_dma_sg_get_page(struct snd_dma_buffer *dmab,
 152                                         size_t offset)
 153 {
 154         struct snd_sg_buf *sgbuf = dmab->private_data;
 155         unsigned int idx = offset >> PAGE_SHIFT;
 156
 157         if (idx >= (unsigned int)sgbuf->pages)
 158                 return NULL;
 159         return sgbuf->page_table[idx];
 160 }
 161
 162 static unsigned int snd_dma_sg_get_chunk_size(struct snd_dma_buffer *dmab,
 163                                               unsigned int ofs,
 164                                               unsigned int size)
 165 {
 166         struct snd_sg_buf *sg = dmab->private_data;
 167         unsigned int start, end, pg;
 168
 169         start = ofs >> PAGE_SHIFT;
 170         end = (ofs + size - 1) >> PAGE_SHIFT;
 171         /* check page continuity */
 172         pg = sg->table[start].addr >> PAGE_SHIFT;
 173         for (;;) {
 174                 start++;
 175                 if (start > end)
 176                         break;
 177                 pg++;
 178                 if ((sg->table[start].addr >> PAGE_SHIFT) != pg)
 179                         return (start << PAGE_SHIFT) - ofs;
 180         }
 181         /* ok, all on continuous pages */
 182         return size;
 183 }
 184
 185 const struct snd_malloc_ops snd_dma_sg_ops = {
 186         .alloc = snd_dma_sg_alloc,
 187         .free = snd_dma_sg_free,
 188         .get_addr = snd_dma_sg_get_addr,
 189         .get_page = snd_dma_sg_get_page,
 190         .get_chunk_size = snd_dma_sg_get_chunk_size,
 191 };