/*
* Allocates some kernel memory that we can use for DMA.
* I think this means that the memory has to map to
* contiguous pages of physical memory.
*/
static struct snd_dma_buffer *get_dmabuf(struct snd_dma_buffer *buf, unsigned long size)
{
if (buf) {
if (snd_dma_alloc_pages_fallback(SNDRV_DMA_TYPE_DEV, snd_dma_isa_data(),
size, buf) < 0) {
snd_printk(KERN_ERR "sscape: Failed to allocate %lu bytes for DMA\n", size);
return NULL;
}
}
return buf;
}
void *snd_malloc_sgbuf_pages(struct device *device,
size_t size, struct snd_dma_buffer *dmab,
size_t *res_size)
{
struct snd_sg_buf *sgbuf;
unsigned int i, pages, chunk, maxpages;
struct snd_dma_buffer tmpb;
struct snd_sg_page *table;
struct page **pgtable;
dmab->area = NULL;
dmab->addr = 0;
dmab->private_data = sgbuf = kzalloc(sizeof(*sgbuf), GFP_KERNEL);
if (! sgbuf)
return NULL;
sgbuf->dev = device;
pages = snd_sgbuf_aligned_pages(size);
sgbuf->tblsize = sgbuf_align_table(pages);
table = kcalloc(sgbuf->tblsize, sizeof(*table), GFP_KERNEL);
if (!table)
goto _failed;
sgbuf->table = table;
pgtable = kcalloc(sgbuf->tblsize, sizeof(*pgtable), GFP_KERNEL);
if (!pgtable)
goto _failed;
sgbuf->page_table = pgtable;
/* allocate pages */
maxpages = MAX_ALLOC_PAGES;
while (pages > 0) {
chunk = pages;
/* don't be too eager to take a huge chunk */
if (chunk > maxpages)
chunk = maxpages;
chunk <<= PAGE_SHIFT;
if (snd_dma_alloc_pages_fallback(SNDRV_DMA_TYPE_DEV, device,
chunk, &tmpb) < 0) {
if (!sgbuf->pages)
return NULL;
if (!res_size)
goto _failed;
size = sgbuf->pages * PAGE_SIZE;
break;
}
chunk = tmpb.bytes >> PAGE_SHIFT;
for (i = 0; i < chunk; i++) {
table->buf = tmpb.area;
table->addr = tmpb.addr;
if (!i)
table->addr |= chunk; /* mark head */
table++;
*pgtable++ = virt_to_page(tmpb.area);
tmpb.area += PAGE_SIZE;
tmpb.addr += PAGE_SIZE;
}
sgbuf->pages += chunk;
pages -= chunk;
if (chunk < maxpages)
maxpages = chunk;
}
sgbuf->size = size;
dmab->area = vmap(sgbuf->page_table, sgbuf->pages, VM_MAP, PAGE_KERNEL);
if (! dmab->area)
goto _failed;
if (res_size)
*res_size = sgbuf->size;
return dmab->area;
_failed:
snd_free_sgbuf_pages(dmab); /* free the table */
return NULL;
}
