// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Digital Audio (PCM) abstract layer
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 */

#include <linux/io.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/moduleparam.h>
#include <linux/export.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/info.h>
#include <sound/initval.h>
#include "pcm_local.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;

static unsigned long max_alloc_per_card = 32UL * 1024UL * 1024UL;
module_param(max_alloc_per_card, ulong, 0644);
MODULE_PARM_DESC(max_alloc_per_card, "Max total allocation bytes per card.");

static void __update_allocated_size(struct snd_card *card, ssize_t bytes)
{
        card->total_pcm_alloc_bytes += bytes;
}

static void update_allocated_size(struct snd_card *card, ssize_t bytes)
{
        guard(mutex)(&card->memory_mutex);
        __update_allocated_size(card, bytes);
}

static void decrease_allocated_size(struct snd_card *card, size_t bytes)
{
        guard(mutex)(&card->memory_mutex);
        WARN_ON(card->total_pcm_alloc_bytes < bytes);
        __update_allocated_size(card, -(ssize_t)bytes);
}

static int do_alloc_pages(struct snd_card *card, int type, struct device *dev,
                          int str, size_t size, struct snd_dma_buffer *dmab)
{
        enum dma_data_direction dir;
        int err;

        /* check and reserve the requested size */
        scoped_guard(mutex, &card->memory_mutex) {
                if (max_alloc_per_card &&
                    card->total_pcm_alloc_bytes + size > max_alloc_per_card)
                        return -ENOMEM;
                __update_allocated_size(card, size);
        }

        if (str == SNDRV_PCM_STREAM_PLAYBACK)
                dir = DMA_TO_DEVICE;
        else
                dir = DMA_FROM_DEVICE;
        err = snd_dma_alloc_dir_pages(type, dev, dir, size, dmab);
        if (!err) {
                /* the actual allocation size might be bigger than requested,
                 * and we need to correct the account
                 */
                if (dmab->bytes != size)
                        update_allocated_size(card, dmab->bytes - size);
        } else {
                /* take back on allocation failure */
                decrease_allocated_size(card, size);
        }
        return err;
}

static void do_free_pages(struct snd_card *card, struct snd_dma_buffer *dmab)
{
        if (!dmab->area)
                return;
        decrease_allocated_size(card, dmab->bytes);
        snd_dma_free_pages(dmab);
        dmab->area = NULL;
}

/*
 * 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, bool no_fallback)
{
        struct snd_dma_buffer *dmab = &substream->dma_buffer;
        struct snd_card *card = substream->pcm->card;
        size_t orig_size = size;
        int err;

        do {
                err = do_alloc_pages(card, dmab->dev.type, dmab->dev.dev,
                                     substream->stream, size, dmab);
                if (err != -ENOMEM)
                        return err;
                if (no_fallback)
                        break;
                size >>= 1;
        } while (size >= snd_minimum_buffer);
        dmab->bytes = 0; /* tell error */
        pr_warn("ALSA pcmC%dD%d%c,%d:%s: cannot preallocate for size %zu\n",
                substream->pcm->card->number, substream->pcm->device,
                substream->stream ? 'c' : 'p', substream->number,
                substream->pcm->name, orig_size);
        return -ENOMEM;
}

/**
 * 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.
 */
void snd_pcm_lib_preallocate_free(struct snd_pcm_substream *substream)
{
        do_free_pages(substream->pcm->card, &substream->dma_buffer);
}

/**
 * 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.
 */
void snd_pcm_lib_preallocate_free_for_all(struct snd_pcm *pcm)
{
        struct snd_pcm_substream *substream;
        int stream;

        for_each_pcm_substream(pcm, stream, substream)
                snd_pcm_lib_preallocate_free(substream);
}
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\n", (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\n", (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;
        struct snd_card *card = substream->pcm->card;
        char line[64], str[64];
        unsigned long size;
        struct snd_dma_buffer new_dmab;

        guard(mutex)(&substream->pcm->open_mutex);
        if (substream->runtime) {
                buffer->error = -EBUSY;
                return;
        }
        if (!snd_info_get_line(buffer, line, sizeof(line))) {
                snd_info_get_str(str, line, sizeof(str));
                buffer->error = kstrtoul(str, 10, &size);
                if (buffer->error != 0)
                        return;
                size *= 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 (do_alloc_pages(card,
                                           substream->dma_buffer.dev.type,
                                           substream->dma_buffer.dev.dev,
                                           substream->stream,
                                           size, &new_dmab) < 0) {
                                buffer->error = -ENOMEM;
                                pr_debug("ALSA pcmC%dD%d%c,%d:%s: cannot preallocate for size %lu\n",
                                         substream->pcm->card->number, substream->pcm->device,
                                         substream->stream ? 'c' : 'p', substream->number,
                                         substream->pcm->name, size);
                                return;
                        }
                        substream->buffer_bytes_max = size;
                } else {
                        substream->buffer_bytes_max = UINT_MAX;
                }
                if (substream->dma_buffer.area)
                        do_free_pages(card, &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;

        entry = snd_info_create_card_entry(substream->pcm->card, "prealloc",
                                           substream->proc_root);
        if (entry) {
                snd_info_set_text_ops(entry, substream,
                                      snd_pcm_lib_preallocate_proc_read);
                entry->c.text.write = snd_pcm_lib_preallocate_proc_write;
                entry->mode |= 0200;
        }
        entry = snd_info_create_card_entry(substream->pcm->card, "prealloc_max",
                                           substream->proc_root);
        if (entry)
                snd_info_set_text_ops(entry, substream,
                                      snd_pcm_lib_preallocate_max_proc_read);
}

#else /* !CONFIG_SND_VERBOSE_PROCFS */
static inline void preallocate_info_init(struct snd_pcm_substream *substream)
{
}
#endif /* CONFIG_SND_VERBOSE_PROCFS */

/*
 * pre-allocate the buffer and create a proc file for the substream
 */
static int preallocate_pages(struct snd_pcm_substream *substream,
                              int type, struct device *data,
                              size_t size, size_t max, bool managed)
{
        int err;

        if (snd_BUG_ON(substream->dma_buffer.dev.type))
                return -EINVAL;

        substream->dma_buffer.dev.type = type;
        substream->dma_buffer.dev.dev = data;

        if (size > 0) {
                if (!max) {
                        /* no fallback, only also inform -ENOMEM */
                        err = preallocate_pcm_pages(substream, size, true);
                        if (err < 0)
                                return err;
                } else if (preallocate_dma &&
                           substream->number < maximum_substreams) {
                        err = preallocate_pcm_pages(substream, size, false);
                        if (err < 0 && err != -ENOMEM)
                                return err;
                }
        }

        if (substream->dma_buffer.bytes > 0)
                substream->buffer_bytes_max = substream->dma_buffer.bytes;
        substream->dma_max = max;
        if (max > 0)
                preallocate_info_init(substream);
        if (managed)
                substream->managed_buffer_alloc = 1;
        return 0;
}

static int preallocate_pages_for_all(struct snd_pcm *pcm, int type,
                                      void *data, size_t size, size_t max,
                                      bool managed)
{
        struct snd_pcm_substream *substream;
        int stream, err;

        for_each_pcm_substream(pcm, stream, substream) {
                err = preallocate_pages(substream, type, data, size, max, managed);
                if (err < 0)
                        return err;
        }
        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 dependent 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.
 */
void snd_pcm_lib_preallocate_pages(struct snd_pcm_substream *substream,
                                  int type, struct device *data,
                                  size_t size, size_t max)
{
        preallocate_pages(substream, type, data, size, max, false);
}
EXPORT_SYMBOL(snd_pcm_lib_preallocate_pages);

/**
 * snd_pcm_lib_preallocate_pages_for_all - pre-allocation for continuous memory type (all substreams)
 * @pcm: the pcm instance
 * @type: DMA type (SNDRV_DMA_TYPE_*)
 * @data: DMA type dependent 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.
 */
void snd_pcm_lib_preallocate_pages_for_all(struct snd_pcm *pcm,
                                          int type, void *data,
                                          size_t size, size_t max)
{
        preallocate_pages_for_all(pcm, type, data, size, max, false);
}
EXPORT_SYMBOL(snd_pcm_lib_preallocate_pages_for_all);

/**
 * snd_pcm_set_managed_buffer - set up buffer management for a substream
 * @substream: the pcm substream instance
 * @type: DMA type (SNDRV_DMA_TYPE_*)
 * @data: DMA type dependent 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, and set the managed
 * buffer allocation mode to the given substream.
 * In this mode, PCM core will allocate a buffer automatically before PCM
 * hw_params ops call, and release the buffer after PCM hw_free ops call
 * as well, so that the driver doesn't need to invoke the allocation and
 * the release explicitly in its callback.
 * When a buffer is actually allocated before the PCM hw_params call, it
 * turns on the runtime buffer_changed flag for drivers changing their h/w
 * parameters accordingly.
 *
 * When @size is non-zero and @max is zero, this tries to allocate for only
 * the exact buffer size without fallback, and may return -ENOMEM.
 * Otherwise, the function tries to allocate smaller chunks if the allocation
 * fails.  This is the behavior of snd_pcm_set_fixed_buffer().
 *
 * When both @size and @max are zero, the function only sets up the buffer
 * for later dynamic allocations. It's used typically for buffers with
 * SNDRV_DMA_TYPE_VMALLOC type.
 *
 * Upon successful buffer allocation and setup, the function returns 0.
 *
 * Return: zero if successful, or a negative error code
 */
int snd_pcm_set_managed_buffer(struct snd_pcm_substream *substream, int type,
                                struct device *data, size_t size, size_t max)
{
        return preallocate_pages(substream, type, data, size, max, true);
}
EXPORT_SYMBOL(snd_pcm_set_managed_buffer);

/**
 * snd_pcm_set_managed_buffer_all - set up buffer management for all substreams
 *      for all substreams
 * @pcm: the pcm instance
 * @type: DMA type (SNDRV_DMA_TYPE_*)
 * @data: DMA type dependent 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 and size, and set the managed_buffer_alloc flag to each substream.
 *
 * Return: zero if successful, or a negative error code
 */
int snd_pcm_set_managed_buffer_all(struct snd_pcm *pcm, int type,
                                   struct device *data,
                                   size_t size, size_t max)
{
        return preallocate_pages_for_all(pcm, type, data, size, max, true);
}
EXPORT_SYMBOL(snd_pcm_set_managed_buffer_all);

/**
 * 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().
 *
 * Return: 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_card *card;
        struct snd_pcm_runtime *runtime;
        struct snd_dma_buffer *dmab = NULL;

        if (PCM_RUNTIME_CHECK(substream))
                return -EINVAL;
        if (snd_BUG_ON(substream->dma_buffer.dev.type ==
                       SNDRV_DMA_TYPE_UNKNOWN))
                return -EINVAL;
        runtime = substream->runtime;
        card = substream->pcm->card;

        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 {
                /* dma_max=0 means the fixed size preallocation */
                if (substream->dma_buffer.area && !substream->dma_max)
                        return -ENOMEM;
                dmab = kzalloc_obj(*dmab);
                if (! dmab)
                        return -ENOMEM;
                dmab->dev = substream->dma_buffer.dev;
                if (do_alloc_pages(card,
                                   substream->dma_buffer.dev.type,
                                   substream->dma_buffer.dev.dev,
                                   substream->stream,
                                   size, dmab) < 0) {
                        kfree(dmab);
                        pr_debug("ALSA pcmC%dD%d%c,%d:%s: cannot allocate for size %zu\n",
                                 substream->pcm->card->number, substream->pcm->device,
                                 substream->stream ? 'c' : 'p', substream->number,
                                 substream->pcm->name, size);
                        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().
 *
 * Return: 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;

        if (PCM_RUNTIME_CHECK(substream))
                return -EINVAL;
        runtime = substream->runtime;
        if (runtime->dma_area == NULL)
                return 0;
        if (runtime->dma_buffer_p != &substream->dma_buffer) {
                struct snd_card *card = substream->pcm->card;

                /* it's a newly allocated buffer.  release it now. */
                do_free_pages(card, 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);