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![Takashi Iwai](/assets/img/avatar_default.png)
We have a few helper functions for making the access to the buffer address easier on SG-buffer. Those are specific to the buffer that is allocated with SG-buffer type, and it makes hard to use both SG and non-SG buffers in the same code. This patch adds a few simple checks and lets the helpers to deal with both SG- and continuous buffers gracefully. It's a preliminary step for the upcoming patch that mimics the buffer type on the fly. Link: https://lore.kernel.org/r/20200615160045.2703-4-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de>
163 lines
3.8 KiB
C
163 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Scatter-Gather buffer
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*
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* Copyright (c) by Takashi Iwai <tiwai@suse.de>
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*/
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#include <linux/slab.h>
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#include <linux/mm.h>
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#include <linux/vmalloc.h>
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#include <linux/export.h>
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#include <sound/memalloc.h>
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/* table entries are align to 32 */
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#define SGBUF_TBL_ALIGN 32
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#define sgbuf_align_table(tbl) ALIGN((tbl), SGBUF_TBL_ALIGN)
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int snd_free_sgbuf_pages(struct snd_dma_buffer *dmab)
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{
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struct snd_sg_buf *sgbuf = dmab->private_data;
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struct snd_dma_buffer tmpb;
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int i;
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if (! sgbuf)
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return -EINVAL;
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vunmap(dmab->area);
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dmab->area = NULL;
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tmpb.dev.type = SNDRV_DMA_TYPE_DEV;
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if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_UC_SG)
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tmpb.dev.type = SNDRV_DMA_TYPE_DEV_UC;
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tmpb.dev.dev = sgbuf->dev;
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for (i = 0; i < sgbuf->pages; i++) {
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if (!(sgbuf->table[i].addr & ~PAGE_MASK))
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continue; /* continuous pages */
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tmpb.area = sgbuf->table[i].buf;
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tmpb.addr = sgbuf->table[i].addr & PAGE_MASK;
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tmpb.bytes = (sgbuf->table[i].addr & ~PAGE_MASK) << PAGE_SHIFT;
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snd_dma_free_pages(&tmpb);
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}
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kfree(sgbuf->table);
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kfree(sgbuf->page_table);
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kfree(sgbuf);
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dmab->private_data = NULL;
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return 0;
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}
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#define MAX_ALLOC_PAGES 32
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void *snd_malloc_sgbuf_pages(struct device *device,
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size_t size, struct snd_dma_buffer *dmab,
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size_t *res_size)
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{
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struct snd_sg_buf *sgbuf;
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unsigned int i, pages, chunk, maxpages;
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struct snd_dma_buffer tmpb;
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struct snd_sg_page *table;
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struct page **pgtable;
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int type = SNDRV_DMA_TYPE_DEV;
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pgprot_t prot = PAGE_KERNEL;
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dmab->area = NULL;
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dmab->addr = 0;
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dmab->private_data = sgbuf = kzalloc(sizeof(*sgbuf), GFP_KERNEL);
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if (! sgbuf)
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return NULL;
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if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_UC_SG) {
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type = SNDRV_DMA_TYPE_DEV_UC;
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#ifdef pgprot_noncached
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prot = pgprot_noncached(PAGE_KERNEL);
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#endif
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}
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sgbuf->dev = device;
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pages = snd_sgbuf_aligned_pages(size);
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sgbuf->tblsize = sgbuf_align_table(pages);
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table = kcalloc(sgbuf->tblsize, sizeof(*table), GFP_KERNEL);
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if (!table)
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goto _failed;
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sgbuf->table = table;
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pgtable = kcalloc(sgbuf->tblsize, sizeof(*pgtable), GFP_KERNEL);
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if (!pgtable)
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goto _failed;
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sgbuf->page_table = pgtable;
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/* allocate pages */
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maxpages = MAX_ALLOC_PAGES;
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while (pages > 0) {
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chunk = pages;
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/* don't be too eager to take a huge chunk */
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if (chunk > maxpages)
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chunk = maxpages;
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chunk <<= PAGE_SHIFT;
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if (snd_dma_alloc_pages_fallback(type, device,
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chunk, &tmpb) < 0) {
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if (!sgbuf->pages)
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goto _failed;
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if (!res_size)
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goto _failed;
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size = sgbuf->pages * PAGE_SIZE;
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break;
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}
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chunk = tmpb.bytes >> PAGE_SHIFT;
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for (i = 0; i < chunk; i++) {
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table->buf = tmpb.area;
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table->addr = tmpb.addr;
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if (!i)
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table->addr |= chunk; /* mark head */
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table++;
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*pgtable++ = virt_to_page(tmpb.area);
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tmpb.area += PAGE_SIZE;
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tmpb.addr += PAGE_SIZE;
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}
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sgbuf->pages += chunk;
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pages -= chunk;
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if (chunk < maxpages)
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maxpages = chunk;
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}
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sgbuf->size = size;
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dmab->area = vmap(sgbuf->page_table, sgbuf->pages, VM_MAP, prot);
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if (! dmab->area)
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goto _failed;
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if (res_size)
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*res_size = sgbuf->size;
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return dmab->area;
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_failed:
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snd_free_sgbuf_pages(dmab); /* free the table */
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return NULL;
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}
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/*
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* compute the max chunk size with continuous pages on sg-buffer
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*/
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unsigned int snd_sgbuf_get_chunk_size(struct snd_dma_buffer *dmab,
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unsigned int ofs, unsigned int size)
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{
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struct snd_sg_buf *sg = dmab->private_data;
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unsigned int start, end, pg;
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if (!sg)
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return size;
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start = ofs >> PAGE_SHIFT;
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end = (ofs + size - 1) >> PAGE_SHIFT;
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/* check page continuity */
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pg = sg->table[start].addr >> PAGE_SHIFT;
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for (;;) {
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start++;
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if (start > end)
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break;
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pg++;
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if ((sg->table[start].addr >> PAGE_SHIFT) != pg)
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return (start << PAGE_SHIFT) - ofs;
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}
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/* ok, all on continuous pages */
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return size;
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}
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EXPORT_SYMBOL(snd_sgbuf_get_chunk_size);
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