[PATCH] kref: avoid an atomic operation in kref_put()

[linux-2.6/openmoko-kernel/knife-kernel.git] / sound / core / pcm_memory.c

/*
 *  Digital Audio (PCM) abstract layer
 *  Copyright (c) by Jaroslav Kysela <perex@suse.cz>
 *
 *
 *   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 <sound/driver.h>
#include <asm/io.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/moduleparam.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/info.h>
#include <sound/initval.h>

static int preallocate_dma = 1;
module_param(preallocate_dma, int, 0444);
MODULE_PARM_DESC(preallocate_dma, "Preallocate DMA memory when the PCM devices are initialized.");

static int maximum_substreams = 4;
module_param(maximum_substreams, int, 0444);
MODULE_PARM_DESC(maximum_substreams, "Maximum substreams with preallocated DMA memory.");

static const size_t snd_minimum_buffer = 16384;


/*
 * try to allocate as the large pages as possible.
 * stores the resultant memory size in *res_size.
 *
 * the minimum size is snd_minimum_buffer.  it should be power of 2.
 */
static int preallocate_pcm_pages(struct snd_pcm_substream *substream, size_t size)
{
        struct snd_dma_buffer *dmab = &substream->dma_buffer;
        int err;

        snd_assert(size > 0, return -EINVAL);

        /* already reserved? */
        if (snd_dma_get_reserved_buf(dmab, substream->dma_buf_id) > 0) {
                if (dmab->bytes >= size)
                        return 0; /* yes */
                /* no, free the reserved block */
                snd_dma_free_pages(dmab);
                dmab->bytes = 0;
        }

        do {
                if ((err = snd_dma_alloc_pages(dmab->dev.type, dmab->dev.dev,
                                               size, dmab)) < 0) {
                        if (err != -ENOMEM)
                                return err; /* fatal error */
                } else
                        return 0;
                size >>= 1;
        } while (size >= snd_minimum_buffer);
        dmab->bytes = 0; /* tell error */
        return 0;
}

/*
 * release the preallocated buffer if not yet done.
 */
static void snd_pcm_lib_preallocate_dma_free(struct snd_pcm_substream *substream)
{
        if (substream->dma_buffer.area == NULL)
                return;
        if (substream->dma_buf_id)
                snd_dma_reserve_buf(&substream->dma_buffer, substream->dma_buf_id);
        else
                snd_dma_free_pages(&substream->dma_buffer);
        substream->dma_buffer.area = NULL;
}

/**
 * snd_pcm_lib_preallocate_free - release the preallocated buffer of the specified substream.
 * @substream: the pcm substream instance
 *
 * Releases the pre-allocated buffer of the given substream.
 *
 * Returns zero if successful, or a negative error code on failure.
 */
int snd_pcm_lib_preallocate_free(struct snd_pcm_substream *substream)
{
        snd_pcm_lib_preallocate_dma_free(substream);
        snd_info_unregister(substream->proc_prealloc_entry);
        substream->proc_prealloc_entry = NULL;
        return 0;
}

/**
 * snd_pcm_lib_preallocate_free_for_all - release all pre-allocated buffers on the pcm
 * @pcm: the pcm instance
 *
 * Releases all the pre-allocated buffers on the given pcm.
 *
 * Returns zero if successful, or a negative error code on failure.
 */
int snd_pcm_lib_preallocate_free_for_all(struct snd_pcm *pcm)
{
        struct snd_pcm_substream *substream;
        int stream;

        for (stream = 0; stream < 2; stream++)
                for (substream = pcm->streams[stream].substream; substream; substream = substream->next)
                        snd_pcm_lib_preallocate_free(substream);
        return 0;
}

#ifdef CONFIG_PROC_FS
/*
 * read callback for prealloc proc file
 *
 * prints the current allocated size in kB.
 */
static void snd_pcm_lib_preallocate_proc_read(struct snd_info_entry *entry,
                                              struct snd_info_buffer *buffer)
{
        struct snd_pcm_substream *substream = entry->private_data;
        snd_iprintf(buffer, "%lu\n", (unsigned long) substream->dma_buffer.bytes / 1024);
}

/*
 * write callback for prealloc proc file
 *
 * accepts the preallocation size in kB.
 */
static void snd_pcm_lib_preallocate_proc_write(struct snd_info_entry *entry,
                                               struct snd_info_buffer *buffer)
{
        struct snd_pcm_substream *substream = entry->private_data;
        char line[64], str[64];
        size_t size;
        struct snd_dma_buffer new_dmab;

        if (substream->runtime) {
                buffer->error = -EBUSY;
                return;
        }
        if (!snd_info_get_line(buffer, line, sizeof(line))) {
                snd_info_get_str(str, line, sizeof(str));
                size = simple_strtoul(str, NULL, 10) * 1024;
                if ((size != 0 && size < 8192) || size > substream->dma_max) {
                        buffer->error = -EINVAL;
                        return;
                }
                if (substream->dma_buffer.bytes == size)
                        return;
                memset(&new_dmab, 0, sizeof(new_dmab));
                new_dmab.dev = substream->dma_buffer.dev;
                if (size > 0) {
                        if (snd_dma_alloc_pages(substream->dma_buffer.dev.type,
                                                substream->dma_buffer.dev.dev,
                                                size, &new_dmab) < 0) {
                                buffer->error = -ENOMEM;
                                return;
                        }
                        substream->buffer_bytes_max = size;
                } else {
                        substream->buffer_bytes_max = UINT_MAX;
                }
                if (substream->dma_buffer.area)
                        snd_dma_free_pages(&substream->dma_buffer);
                substream->dma_buffer = new_dmab;
        } else {
                buffer->error = -EINVAL;
        }
}

static inline void preallocate_info_init(struct snd_pcm_substream *substream)
{
        struct snd_info_entry *entry;

        if ((entry = snd_info_create_card_entry(substream->pcm->card, "prealloc", substream->proc_root)) != NULL) {
                entry->c.text.read_size = 64;
                entry->c.text.read = snd_pcm_lib_preallocate_proc_read;
                entry->c.text.write_size = 64;
                entry->c.text.write = snd_pcm_lib_preallocate_proc_write;
                entry->mode |= S_IWUSR;
                entry->private_data = substream;
                if (snd_info_register(entry) < 0) {
                        snd_info_free_entry(entry);
                        entry = NULL;
                }
        }
        substream->proc_prealloc_entry = entry;
}

#else /* !CONFIG_PROC_FS */
#define preallocate_info_init(s)
#endif

/*
 * pre-allocate the buffer and create a proc file for the substream
 */
static int snd_pcm_lib_preallocate_pages1(struct snd_pcm_substream *substream,
                                          size_t size, size_t max)
{

        if (size > 0 && preallocate_dma && substream->number < maximum_substreams)
                preallocate_pcm_pages(substream, size);

        if (substream->dma_buffer.bytes > 0)
                substream->buffer_bytes_max = substream->dma_buffer.bytes;
        substream->dma_max = max;
        preallocate_info_init(substream);
        return 0;
}


/**
 * snd_pcm_lib_preallocate_pages - pre-allocation for the given DMA type
 * @substream: the pcm substream instance
 * @type: DMA type (SNDRV_DMA_TYPE_*)
 * @data: DMA type dependant data
 * @size: the requested pre-allocation size in bytes
 * @max: the max. allowed pre-allocation size
 *
 * Do pre-allocation for the given DMA buffer type.
 *
 * When substream->dma_buf_id is set, the function tries to look for
 * the reserved buffer, and the buffer is not freed but reserved at
 * destruction time.  The dma_buf_id must be unique for all systems
 * (in the same DMA buffer type) e.g. using snd_dma_pci_buf_id().
 *
 * Returns zero if successful, or a negative error code on failure.
 */
int snd_pcm_lib_preallocate_pages(struct snd_pcm_substream *substream,
                                  int type, struct device *data,
                                  size_t size, size_t max)
{
        substream->dma_buffer.dev.type = type;
        substream->dma_buffer.dev.dev = data;
        return snd_pcm_lib_preallocate_pages1(substream, size, max);
}

/**
 * snd_pcm_lib_preallocate_pages_for_all - pre-allocation for continous memory type (all substreams)
 * @pcm: the pcm instance
 * @type: DMA type (SNDRV_DMA_TYPE_*)
 * @data: DMA type dependant data
 * @size: the requested pre-allocation size in bytes
 * @max: the max. allowed pre-allocation size
 *
 * Do pre-allocation to all substreams of the given pcm for the
 * specified DMA type.
 *
 * Returns zero if successful, or a negative error code on failure.
 */
int snd_pcm_lib_preallocate_pages_for_all(struct snd_pcm *pcm,
                                          int type, void *data,
                                          size_t size, size_t max)
{
        struct snd_pcm_substream *substream;
        int stream, err;

        for (stream = 0; stream < 2; stream++)
                for (substream = pcm->streams[stream].substream; substream; substream = substream->next)
                        if ((err = snd_pcm_lib_preallocate_pages(substream, type, data, size, max)) < 0)
                                return err;
        return 0;
}

/**
 * snd_pcm_sgbuf_ops_page - get the page struct at the given offset
 * @substream: the pcm substream instance
 * @offset: the buffer offset
 *
 * Returns the page struct at the given buffer offset.
 * Used as the page callback of PCM ops.
 */
struct page *snd_pcm_sgbuf_ops_page(struct snd_pcm_substream *substream, unsigned long offset)
{
        struct snd_sg_buf *sgbuf = snd_pcm_substream_sgbuf(substream);

        unsigned int idx = offset >> PAGE_SHIFT;
        if (idx >= (unsigned int)sgbuf->pages)
                return NULL;
        return sgbuf->page_table[idx];
}

/**
 * snd_pcm_lib_malloc_pages - allocate the DMA buffer
 * @substream: the substream to allocate the DMA buffer to
 * @size: the requested buffer size in bytes
 *
 * Allocates the DMA buffer on the BUS type given earlier to
 * snd_pcm_lib_preallocate_xxx_pages().
 *
 * Returns 1 if the buffer is changed, 0 if not changed, or a negative
 * code on failure.
 */
int snd_pcm_lib_malloc_pages(struct snd_pcm_substream *substream, size_t size)
{
        struct snd_pcm_runtime *runtime;
        struct snd_dma_buffer *dmab = NULL;

        snd_assert(substream->dma_buffer.dev.type != SNDRV_DMA_TYPE_UNKNOWN, return -EINVAL);
        snd_assert(substream != NULL, return -EINVAL);
        runtime = substream->runtime;
        snd_assert(runtime != NULL, return -EINVAL);

        if (runtime->dma_buffer_p) {
                /* perphaps, we might free the large DMA memory region
                   to save some space here, but the actual solution
                   costs us less time */
                if (runtime->dma_buffer_p->bytes >= size) {
                        runtime->dma_bytes = size;
                        return 0;       /* ok, do not change */
                }
                snd_pcm_lib_free_pages(substream);
        }
        if (substream->dma_buffer.area != NULL &&
            substream->dma_buffer.bytes >= size) {
                dmab = &substream->dma_buffer; /* use the pre-allocated buffer */
        } else {
                dmab = kzalloc(sizeof(*dmab), GFP_KERNEL);
                if (! dmab)
                        return -ENOMEM;
                dmab->dev = substream->dma_buffer.dev;
                if (snd_dma_alloc_pages(substream->dma_buffer.dev.type,
                                        substream->dma_buffer.dev.dev,
                                        size, dmab) < 0) {
                        kfree(dmab);
                        return -ENOMEM;
                }
        }
        snd_pcm_set_runtime_buffer(substream, dmab);
        runtime->dma_bytes = size;
        return 1;                       /* area was changed */
}

/**
 * snd_pcm_lib_free_pages - release the allocated DMA buffer.
 * @substream: the substream to release the DMA buffer
 *
 * Releases the DMA buffer allocated via snd_pcm_lib_malloc_pages().
 *
 * Returns zero if successful, or a negative error code on failure.
 */
int snd_pcm_lib_free_pages(struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime;

        snd_assert(substream != NULL, return -EINVAL);
        runtime = substream->runtime;
        snd_assert(runtime != NULL, return -EINVAL);
        if (runtime->dma_area == NULL)
                return 0;
        if (runtime->dma_buffer_p != &substream->dma_buffer) {
                /* it's a newly allocated buffer.  release it now. */
                snd_dma_free_pages(runtime->dma_buffer_p);
                kfree(runtime->dma_buffer_p);
        }
        snd_pcm_set_runtime_buffer(substream, NULL);
        return 0;
}