/*
 *  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 <sound/pcm.h>
#include <sound/info.h>
#include <sound/initval.h>

static int preallocate_dma = 1;
MODULE_PARM(preallocate_dma, "i");
MODULE_PARM_DESC(preallocate_dma, "Preallocate DMA memory when the PCM devices are initialized.");
MODULE_PARM_SYNTAX(preallocate_dma, SNDRV_BOOLEAN_TRUE_DESC);

static int maximum_substreams = 4;
MODULE_PARM(maximum_substreams, "i");
MODULE_PARM_DESC(maximum_substreams, "Maximum substreams with preallocated DMA memory.");
MODULE_PARM_SYNTAX(maximum_substreams, SNDRV_BOOLEAN_TRUE_DESC);

const static 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(snd_pcm_substream_t *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(snd_pcm_substream_t *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(snd_pcm_substream_t *substream)
{
    snd_pcm_lib_preallocate_dma_free(substream);
    if (substream->proc_prealloc_entry) {
        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(snd_pcm_t *pcm)
{
    snd_pcm_substream_t *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;
}

/*
 * read callback for prealloc proc file
 *
 * prints the current allocated size in kB.
 */
static void snd_pcm_lib_preallocate_proc_read(snd_info_entry_t *entry,
                                              snd_info_buffer_t *buffer)
{
    snd_pcm_substream_t *substream = (snd_pcm_substream_t *)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(snd_info_entry_t *entry,
                                               snd_info_buffer_t *buffer)
{
    snd_pcm_substream_t *substream = (snd_pcm_substream_t *)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;
    }
}

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

    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;
    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->private_data = substream;
        if (snd_info_register(entry) < 0) {
            snd_info_free_entry(entry);
            entry = NULL;
        }
    }
    substream->proc_prealloc_entry = entry;
    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(snd_pcm_substream_t *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)
 * @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 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(snd_pcm_t *pcm,
					  int type, void *data,
					  size_t size, size_t max)
{
	snd_pcm_substream_t *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(snd_pcm_substream_t *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 by
 * 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(snd_pcm_substream_t *substream, size_t size)
{
	snd_pcm_runtime_t *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 = (struct snd_dma_buffer *)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(snd_pcm_substream_t *substream)
{
	snd_pcm_runtime_t *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;
}


