root/sound/core/sgbuf.c

DEFINITIONS

1. snd_free_sgbuf_pages
2. snd_malloc_sgbuf_pages

/*
 * Scatter-Gather buffer
 *
 *  Copyright (c) by Takashi Iwai <tiwai@suse.de>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   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;

        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);
        }
        if (dmab->area)
                vunmap(dmab->area);
        dmab->area = NULL;

        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;
}