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Linux/sound/core/sgbuf.c

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  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);
164 

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