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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 #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 };
192 

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