/*
   *  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);

  #ifdef CONFIG_SND_VERBOSE_PROCFS

  	snd_info_free_entry(substream->proc_prealloc_max_entry);
  	substream->proc_prealloc_max_entry = NULL;

  	snd_info_free_entry(substream->proc_prealloc_entry);

  	substream->proc_prealloc_entry = NULL;

  #endif

  	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;
  }

  EXPORT_SYMBOL(snd_pcm_lib_preallocate_free_for_all);

  #ifdef CONFIG_SND_VERBOSE_PROCFS

  /*
   * 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
  ", (unsigned long) substream->dma_buffer.bytes / 1024);
  }
  
  /*

   * read callback for prealloc_max proc file
   *
   * prints the maximum allowed size in kB.
   */
  static void snd_pcm_lib_preallocate_max_proc_read(struct snd_info_entry *entry,
  						  struct snd_info_buffer *buffer)
  {
  	struct snd_pcm_substream *substream = entry->private_data;
  	snd_iprintf(buffer, "%lu
  ", (unsigned long) substream->dma_max / 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 = snd_pcm_lib_preallocate_proc_read;

  		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;

  	if ((entry = snd_info_create_card_entry(substream->pcm->card, "prealloc_max", substream->proc_root)) != NULL) {
  		entry->c.text.read = snd_pcm_lib_preallocate_max_proc_read;
  		entry->private_data = substream;
  		if (snd_info_register(entry) < 0) {
  			snd_info_free_entry(entry);
  			entry = NULL;
  		}
  	}
  	substream->proc_prealloc_max_entry = entry;

  }

  #else /* !CONFIG_SND_VERBOSE_PROCFS */

  #define preallocate_info_init(s)

  #endif /* CONFIG_SND_VERBOSE_PROCFS */

  
  /*
   * 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);
  }

  EXPORT_SYMBOL(snd_pcm_lib_preallocate_pages);

  /**
   * 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;
  }

  EXPORT_SYMBOL(snd_pcm_lib_preallocate_pages_for_all);

  /**
   * 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];
  }

  EXPORT_SYMBOL(snd_pcm_sgbuf_ops_page);

  /**
   * 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 */
  }

  EXPORT_SYMBOL(snd_pcm_lib_malloc_pages);

  /**
   * 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;
  }

  
  EXPORT_SYMBOL(snd_pcm_lib_free_pages);