sgbuf.rar_SCATTER GATHER

/* * Scatter-Gather buffer * * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * */ #include <linux/slab.h> #include <linux/mm.h> #include <linux/vmalloc.h> #include <sound/memalloc.h> /* table entries are align to 32 */ #define SGBUF_TBL_ALIGN 32 #define sgbuf_align_table(tbl) ALIGN((tbl), SGBUF_TBL_ALIGN) int snd_free_sgbuf_pages(struct snd_dma_buffer *dmab) { struct snd_sg_buf *sgbuf = dmab->private_data; struct snd_dma_buffer tmpb; int i; if (! sgbuf) return -EINVAL; if (dmab->area) vunmap(dmab->area); dmab->area = NULL; tmpb.dev.type = SNDRV_DMA_TYPE_DEV; tmpb.dev.dev = sgbuf->dev; for (i = 0; i < sgbuf->pages; i++) { if (!(sgbuf->table[i].addr & ~PAGE_MASK)) continue; /* continuous pages */ tmpb.area = sgbuf->table[i].buf; tmpb.addr = sgbuf->table[i].addr & PAGE_MASK; tmpb.bytes = (sgbuf->table[i].addr & ~PAGE_MASK) << PAGE_SHIFT; snd_dma_free_pages(&tmpb); } kfree(sgbuf->table); kfree(sgbuf->page_table); kfree(sgbuf); dmab->private_data = NULL; return 0; } #define MAX_ALLOC_PAGES 32 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; }