text: // SPDX-License-Identifier: GPL-2.0
  /*
   * sound.c - Sound component for Mostcore
   *
   * Copyright (C) 2015 Microchip Technology Germany II GmbH & Co. KG
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/module.h>
  #include <linux/printk.h>
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/init.h>
  #include <sound/core.h>
  #include <sound/pcm.h>
  #include <sound/pcm_params.h>
  #include <linux/sched.h>
  #include <linux/kthread.h>
  #include <linux/most.h>
  
  #define DRIVER_NAME "sound"
  #define STRING_SIZE	80
  
  static struct most_component comp;
  
  /**
   * struct channel - private structure to keep channel specific data
   * @substream: stores the substream structure
   * @iface: interface for which the channel belongs to
   * @cfg: channel configuration
   * @card: registered sound card
   * @list: list for private use
   * @id: channel index
   * @period_pos: current period position (ring buffer)
   * @buffer_pos: current buffer position (ring buffer)
   * @is_stream_running: identifies whether a stream is running or not
   * @opened: set when the stream is opened
   * @playback_task: playback thread
   * @playback_waitq: waitq used by playback thread
   */
  struct channel {
  	struct snd_pcm_substream *substream;
  	struct snd_pcm_hardware pcm_hardware;
  	struct most_interface *iface;
  	struct most_channel_config *cfg;
  	struct snd_card *card;
  	struct list_head list;
  	int id;
  	unsigned int period_pos;
  	unsigned int buffer_pos;
  	bool is_stream_running;
  	struct task_struct *playback_task;
  	wait_queue_head_t playback_waitq;
  	void (*copy_fn)(void *alsa, void *most, unsigned int bytes);
  };
  
  struct sound_adapter {
  	struct list_head dev_list;
  	struct most_interface *iface;
  	struct snd_card *card;
  	struct list_head list;
  	bool registered;
  	int pcm_dev_idx;
  };
  
  static struct list_head adpt_list;
  
  #define MOST_PCM_INFO (SNDRV_PCM_INFO_MMAP | \
  		       SNDRV_PCM_INFO_MMAP_VALID | \
  		       SNDRV_PCM_INFO_BATCH | \
  		       SNDRV_PCM_INFO_INTERLEAVED | \
  		       SNDRV_PCM_INFO_BLOCK_TRANSFER)
  
  #define swap16(val) ( \
  	(((u16)(val) << 8) & (u16)0xFF00) | \
  	(((u16)(val) >> 8) & (u16)0x00FF))
  
  #define swap32(val) ( \
  	(((u32)(val) << 24) & (u32)0xFF000000) | \
  	(((u32)(val) <<  8) & (u32)0x00FF0000) | \
  	(((u32)(val) >>  8) & (u32)0x0000FF00) | \
  	(((u32)(val) >> 24) & (u32)0x000000FF))
  
  static void swap_copy16(u16 *dest, const u16 *source, unsigned int bytes)
  {
  	unsigned int i = 0;
  
  	while (i < (bytes / 2)) {
  		dest[i] = swap16(source[i]);
  		i++;
  	}
  }
  
  static void swap_copy24(u8 *dest, const u8 *source, unsigned int bytes)
  {
  	unsigned int i = 0;
  
  	if (bytes < 2)
  		return;
  	while (i < bytes - 2) {
  		dest[i] = source[i + 2];
  		dest[i + 1] = source[i + 1];
  		dest[i + 2] = source[i];
  		i += 3;
  	}
  }
  
  static void swap_copy32(u32 *dest, const u32 *source, unsigned int bytes)
  {
  	unsigned int i = 0;
  
  	while (i < bytes / 4) {
  		dest[i] = swap32(source[i]);
  		i++;
  	}
  }
  
  static void alsa_to_most_memcpy(void *alsa, void *most, unsigned int bytes)
  {
  	memcpy(most, alsa, bytes);
  }
  
  static void alsa_to_most_copy16(void *alsa, void *most, unsigned int bytes)
  {
  	swap_copy16(most, alsa, bytes);
  }
  
  static void alsa_to_most_copy24(void *alsa, void *most, unsigned int bytes)
  {
  	swap_copy24(most, alsa, bytes);
  }
  
  static void alsa_to_most_copy32(void *alsa, void *most, unsigned int bytes)
  {
  	swap_copy32(most, alsa, bytes);
  }
  
  static void most_to_alsa_memcpy(void *alsa, void *most, unsigned int bytes)
  {
  	memcpy(alsa, most, bytes);
  }
  
  static void most_to_alsa_copy16(void *alsa, void *most, unsigned int bytes)
  {
  	swap_copy16(alsa, most, bytes);
  }
  
  static void most_to_alsa_copy24(void *alsa, void *most, unsigned int bytes)
  {
  	swap_copy24(alsa, most, bytes);
  }
  
  static void most_to_alsa_copy32(void *alsa, void *most, unsigned int bytes)
  {
  	swap_copy32(alsa, most, bytes);
  }
  
  /**
   * get_channel - get pointer to channel
   * @iface: interface structure
   * @channel_id: channel ID
   *
   * This traverses the channel list and returns the channel matching the
   * ID and interface.
   *
   * Returns pointer to channel on success or NULL otherwise.
   */
  static struct channel *get_channel(struct most_interface *iface,
  				   int channel_id)
  {
  	struct sound_adapter *adpt = iface->priv;
  	struct channel *channel, *tmp;
  
  	list_for_each_entry_safe(channel, tmp, &adpt->dev_list, list) {
  		if ((channel->iface == iface) && (channel->id == channel_id))
  			return channel;
  	}
  	return NULL;
  }
  
  /**
   * copy_data - implements data copying function
   * @channel: channel
   * @mbo: MBO from core
   *
   * Copy data from/to ring buffer to/from MBO and update the buffer position
   */
  static bool copy_data(struct channel *channel, struct mbo *mbo)
  {
  	struct snd_pcm_runtime *const runtime = channel->substream->runtime;
  	unsigned int const frame_bytes = channel->cfg->subbuffer_size;
  	unsigned int const buffer_size = runtime->buffer_size;
  	unsigned int frames;
  	unsigned int fr0;
  
  	if (channel->cfg->direction & MOST_CH_RX)
  		frames = mbo->processed_length / frame_bytes;
  	else
  		frames = mbo->buffer_length / frame_bytes;
  	fr0 = min(buffer_size - channel->buffer_pos, frames);
  
  	channel->copy_fn(runtime->dma_area + channel->buffer_pos * frame_bytes,
  			 mbo->virt_address,
  			 fr0 * frame_bytes);
  
  	if (frames > fr0) {
  		/* wrap around at end of ring buffer */
  		channel->copy_fn(runtime->dma_area,
  				 mbo->virt_address + fr0 * frame_bytes,
  				 (frames - fr0) * frame_bytes);
  	}
  
  	channel->buffer_pos += frames;
  	if (channel->buffer_pos >= buffer_size)
  		channel->buffer_pos -= buffer_size;
  	channel->period_pos += frames;
  	if (channel->period_pos >= runtime->period_size) {
  		channel->period_pos -= runtime->period_size;
  		return true;
  	}
  	return false;
  }
  
  /**
   * playback_thread - function implements the playback thread
   * @data: private data
   *
   * Thread which does the playback functionality in a loop. It waits for a free
   * MBO from mostcore for a particular channel and copy the data from ring buffer
   * to MBO. Submit the MBO back to mostcore, after copying the data.
   *
   * Returns 0 on success or error code otherwise.
   */
  static int playback_thread(void *data)
  {
  	struct channel *const channel = data;
  
  	while (!kthread_should_stop()) {
  		struct mbo *mbo = NULL;
  		bool period_elapsed = false;
  
  		wait_event_interruptible(
  			channel->playback_waitq,
  			kthread_should_stop() ||
  			(channel->is_stream_running &&
  			 (mbo = most_get_mbo(channel->iface, channel->id,
  					     &comp))));
  		if (!mbo)
  			continue;
  
  		if (channel->is_stream_running)
  			period_elapsed = copy_data(channel, mbo);
  		else
  			memset(mbo->virt_address, 0, mbo->buffer_length);
  
  		most_submit_mbo(mbo);
  		if (period_elapsed)
  			snd_pcm_period_elapsed(channel->substream);
  	}
  	return 0;
  }
  
  /**
   * pcm_open - implements open callback function for PCM middle layer
   * @substream: pointer to ALSA PCM substream
   *
   * This is called when a PCM substream is opened. At least, the function should
   * initialize the runtime->hw record.
   *
   * Returns 0 on success or error code otherwise.
   */
  static int pcm_open(struct snd_pcm_substream *substream)
  {
  	struct channel *channel = substream->private_data;
  	struct snd_pcm_runtime *runtime = substream->runtime;
  	struct most_channel_config *cfg = channel->cfg;
  	int ret;
  
  	channel->substream = substream;
  
  	if (cfg->direction == MOST_CH_TX) {
  		channel->playback_task = kthread_run(playback_thread, channel,
  						     "most_audio_playback");
  		if (IS_ERR(channel->playback_task)) {
  			pr_err("Couldn't start thread\n");
  			return PTR_ERR(channel->playback_task);
  		}
  	}
  
  	ret = most_start_channel(channel->iface, channel->id, &comp);
  	if (ret) {
  		pr_err("most_start_channel() failed!\n");
  		if (cfg->direction == MOST_CH_TX)
  			kthread_stop(channel->playback_task);
  		return ret;
  	}
  
  	runtime->hw = channel->pcm_hardware;
  	return 0;
  }
  
  /**
   * pcm_close - implements close callback function for PCM middle layer
   * @substream: sub-stream pointer
   *
   * Obviously, this is called when a PCM substream is closed. Any private
   * instance for a PCM substream allocated in the open callback will be
   * released here.
   *
   * Returns 0 on success or error code otherwise.
   */
  static int pcm_close(struct snd_pcm_substream *substream)
  {
  	struct channel *channel = substream->private_data;
  
  	if (channel->cfg->direction == MOST_CH_TX)
  		kthread_stop(channel->playback_task);
  	most_stop_channel(channel->iface, channel->id, &comp);
  	return 0;
  }
  
  /**
   * pcm_prepare - implements prepare callback function for PCM middle layer
   * @substream: substream pointer
   *
   * This callback is called when the PCM is "prepared". Format rate, sample rate,
   * etc., can be set here. This callback can be called many times at each setup.
   *
   * Returns 0 on success or error code otherwise.
   */
  static int pcm_prepare(struct snd_pcm_substream *substream)
  {
  	struct channel *channel = substream->private_data;
  	struct snd_pcm_runtime *runtime = substream->runtime;
  	struct most_channel_config *cfg = channel->cfg;
  	int width = snd_pcm_format_physical_width(runtime->format);
  
  	channel->copy_fn = NULL;
  
  	if (cfg->direction == MOST_CH_TX) {
  		if (snd_pcm_format_big_endian(runtime->format) || width == 8)
  			channel->copy_fn = alsa_to_most_memcpy;
  		else if (width == 16)
  			channel->copy_fn = alsa_to_most_copy16;
  		else if (width == 24)
  			channel->copy_fn = alsa_to_most_copy24;
  		else if (width == 32)
  			channel->copy_fn = alsa_to_most_copy32;
  	} else {
  		if (snd_pcm_format_big_endian(runtime->format) || width == 8)
  			channel->copy_fn = most_to_alsa_memcpy;
  		else if (width == 16)
  			channel->copy_fn = most_to_alsa_copy16;
  		else if (width == 24)
  			channel->copy_fn = most_to_alsa_copy24;
  		else if (width == 32)
  			channel->copy_fn = most_to_alsa_copy32;
  	}
  
  	if (!channel->copy_fn)
  		return -EINVAL;
  	channel->period_pos = 0;
  	channel->buffer_pos = 0;
  	return 0;
  }
  
  /**
   * pcm_trigger - implements trigger callback function for PCM middle layer
   * @substream: substream pointer
   * @cmd: action to perform
   *
   * This is called when the PCM is started, stopped or paused. The action will be
   * specified in the second argument, SNDRV_PCM_TRIGGER_XXX
   *
   * Returns 0 on success or error code otherwise.
   */
  static int pcm_trigger(struct snd_pcm_substream *substream, int cmd)
  {
  	struct channel *channel = substream->private_data;
  
  	switch (cmd) {
  	case SNDRV_PCM_TRIGGER_START:
  		channel->is_stream_running = true;
  		wake_up_interruptible(&channel->playback_waitq);
  		return 0;
  
  	case SNDRV_PCM_TRIGGER_STOP:
  		channel->is_stream_running = false;
  		return 0;
  
  	default:
  		return -EINVAL;
  	}
  	return 0;
  }
  
  /**
   * pcm_pointer - implements pointer callback function for PCM middle layer
   * @substream: substream pointer
   *
   * This callback is called when the PCM middle layer inquires the current
   * hardware position on the buffer. The position must be returned in frames,
   * ranging from 0 to buffer_size-1.
   */
  static snd_pcm_uframes_t pcm_pointer(struct snd_pcm_substream *substream)
  {
  	struct channel *channel = substream->private_data;
  
  	return channel->buffer_pos;
  }
  
  /**
   * Initialization of struct snd_pcm_ops
   */
  static const struct snd_pcm_ops pcm_ops = {
  	.open       = pcm_open,
  	.close      = pcm_close,
  	.prepare    = pcm_prepare,
  	.trigger    = pcm_trigger,
  	.pointer    = pcm_pointer,
  };
  
  static int split_arg_list(char *buf, u16 *ch_num, char **sample_res)
  {
  	char *num;
  	int ret;
  
  	num = strsep(&buf, "x");
  	if (!num)
  		goto err;
  	ret = kstrtou16(num, 0, ch_num);
  	if (ret)
  		goto err;
  	*sample_res = strsep(&buf, ".\n");
  	if (!*sample_res)
  		goto err;
  	return 0;
  
  err:
  	pr_err("Bad PCM format\n");
  	return -EINVAL;
  }
  
  static const struct sample_resolution_info {
  	const char *sample_res;
  	int bytes;
  	u64 formats;
  } sinfo[] = {
  	{ "8", 1, SNDRV_PCM_FMTBIT_S8 },
  	{ "16", 2, SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE },
  	{ "24", 3, SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_3BE },
  	{ "32", 4, SNDRV_PCM_FMTBIT_S32_LE | SNDRV_PCM_FMTBIT_S32_BE },
  };
  
  static int audio_set_hw_params(struct snd_pcm_hardware *pcm_hw,
  			       u16 ch_num, char *sample_res,
  			       struct most_channel_config *cfg)
  {
  	int i;
  
  	for (i = 0; i < ARRAY_SIZE(sinfo); i++) {
  		if (!strcmp(sample_res, sinfo[i].sample_res))
  			goto found;
  	}
  	pr_err("Unsupported PCM format\n");
  	return -EINVAL;
  
  found:
  	if (!ch_num) {
  		pr_err("Bad number of channels\n");
  		return -EINVAL;
  	}
  
  	if (cfg->subbuffer_size != ch_num * sinfo[i].bytes) {
  		pr_err("Audio resolution doesn't fit subbuffer size\n");
  		return -EINVAL;
  	}
  
  	pcm_hw->info = MOST_PCM_INFO;
  	pcm_hw->rates = SNDRV_PCM_RATE_48000;
  	pcm_hw->rate_min = 48000;
  	pcm_hw->rate_max = 48000;
  	pcm_hw->buffer_bytes_max = cfg->num_buffers * cfg->buffer_size;
  	pcm_hw->period_bytes_min = cfg->buffer_size;
  	pcm_hw->period_bytes_max = cfg->buffer_size;
  	pcm_hw->periods_min = 1;
  	pcm_hw->periods_max = cfg->num_buffers;
  	pcm_hw->channels_min = ch_num;
  	pcm_hw->channels_max = ch_num;
  	pcm_hw->formats = sinfo[i].formats;
  	return 0;
  }
  
  static void release_adapter(struct sound_adapter *adpt)
  {
  	struct channel *channel, *tmp;
  
  	list_for_each_entry_safe(channel, tmp, &adpt->dev_list, list) {
  		list_del(&channel->list);
  		kfree(channel);
  	}
  	if (adpt->card)
  		snd_card_free(adpt->card);
  	list_del(&adpt->list);
  	kfree(adpt);
  }
  
  /**
   * audio_probe_channel - probe function of the driver module
   * @iface: pointer to interface instance
   * @channel_id: channel index/ID
   * @cfg: pointer to actual channel configuration
   * @arg_list: string that provides the name of the device to be created in /dev
   *	      plus the desired audio resolution
   *
   * Creates sound card, pcm device, sets pcm ops and registers sound card.
   *
   * Returns 0 on success or error code otherwise.
   */
  static int audio_probe_channel(struct most_interface *iface, int channel_id,
  			       struct most_channel_config *cfg,
  			       char *device_name, char *arg_list)
  {
  	struct channel *channel;
  	struct sound_adapter *adpt;
  	struct snd_pcm *pcm;
  	int playback_count = 0;
  	int capture_count = 0;
  	int ret;
  	int direction;
  	u16 ch_num;
  	char *sample_res;
  	char arg_list_cpy[STRING_SIZE];
  
  	if (cfg->data_type != MOST_CH_SYNC) {
  		pr_err("Incompatible channel type\n");
  		return -EINVAL;
  	}
  	strlcpy(arg_list_cpy, arg_list, STRING_SIZE);
  	ret = split_arg_list(arg_list_cpy, &ch_num, &sample_res);
  	if (ret < 0)
  		return ret;
  
  	list_for_each_entry(adpt, &adpt_list, list) {
  		if (adpt->iface != iface)
  			continue;
  		if (adpt->registered)
  			return -ENOSPC;
  		adpt->pcm_dev_idx++;
  		goto skip_adpt_alloc;
  	}
  	adpt = kzalloc(sizeof(*adpt), GFP_KERNEL);
  	if (!adpt)
  		return -ENOMEM;
  
  	adpt->iface = iface;
  	INIT_LIST_HEAD(&adpt->dev_list);
  	iface->priv = adpt;
  	list_add_tail(&adpt->list, &adpt_list);
  	ret = snd_card_new(iface->driver_dev, -1, "INIC", THIS_MODULE,
  			   sizeof(*channel), &adpt->card);
  	if (ret < 0)
  		goto err_free_adpt;
  	snprintf(adpt->card->driver, sizeof(adpt->card->driver),
  		 "%s", DRIVER_NAME);
  	snprintf(adpt->card->shortname, sizeof(adpt->card->shortname),
  		 "Microchip INIC");
  	snprintf(adpt->card->longname, sizeof(adpt->card->longname),
  		 "%s at %s", adpt->card->shortname, iface->description);
  skip_adpt_alloc:
  	if (get_channel(iface, channel_id)) {
  		pr_err("channel (%s:%d) is already linked\n",
  		       iface->description, channel_id);
  		return -EEXIST;
  	}
  
  	if (cfg->direction == MOST_CH_TX) {
  		playback_count = 1;
  		direction = SNDRV_PCM_STREAM_PLAYBACK;
  	} else {
  		capture_count = 1;
  		direction = SNDRV_PCM_STREAM_CAPTURE;
  	}
  	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
  	if (!channel) {
  		ret = -ENOMEM;
  		goto err_free_adpt;
  	}
  	channel->card = adpt->card;
  	channel->cfg = cfg;
  	channel->iface = iface;
  	channel->id = channel_id;
  	init_waitqueue_head(&channel->playback_waitq);
  	list_add_tail(&channel->list, &adpt->dev_list);
  
  	ret = audio_set_hw_params(&channel->pcm_hardware, ch_num, sample_res,
  				  cfg);
  	if (ret)
  		goto err_free_adpt;
  
  	ret = snd_pcm_new(adpt->card, device_name, adpt->pcm_dev_idx,
  			  playback_count, capture_count, &pcm);
  
  	if (ret < 0)
  		goto err_free_adpt;
  
  	pcm->private_data = channel;
  	strscpy(pcm->name, device_name, sizeof(pcm->name));
  	snd_pcm_set_ops(pcm, direction, &pcm_ops);
  	snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, 0, 0);
  	return 0;
  
  err_free_adpt:
  	release_adapter(adpt);
  	return ret;
  }
  
  static int audio_create_sound_card(void)
  {
  	int ret;
  	struct sound_adapter *adpt;
  
  	list_for_each_entry(adpt, &adpt_list, list) {
  		if (!adpt->registered)
  			goto adpt_alloc;
  	}
  	return -ENODEV;
  adpt_alloc:
  	ret = snd_card_register(adpt->card);
  	if (ret < 0) {
  		release_adapter(adpt);
  		return ret;
  	}
  	adpt->registered = true;
  	return 0;
  }
  
  /**
   * audio_disconnect_channel - function to disconnect a channel
   * @iface: pointer to interface instance
   * @channel_id: channel index
   *
   * This frees allocated memory and removes the sound card from ALSA
   *
   * Returns 0 on success or error code otherwise.
   */
  static int audio_disconnect_channel(struct most_interface *iface,
  				    int channel_id)
  {
  	struct channel *channel;
  	struct sound_adapter *adpt = iface->priv;
  
  	channel = get_channel(iface, channel_id);
  	if (!channel)
  		return -EINVAL;
  
  	list_del(&channel->list);
  
  	kfree(channel);
  	if (list_empty(&adpt->dev_list))
  		release_adapter(adpt);
  	return 0;
  }
  
  /**
   * audio_rx_completion - completion handler for rx channels
   * @mbo: pointer to buffer object that has completed
   *
   * This searches for the channel this MBO belongs to and copy the data from MBO
   * to ring buffer
   *
   * Returns 0 on success or error code otherwise.
   */
  static int audio_rx_completion(struct mbo *mbo)
  {
  	struct channel *channel = get_channel(mbo->ifp, mbo->hdm_channel_id);
  	bool period_elapsed = false;
  
  	if (!channel)
  		return -EINVAL;
  	if (channel->is_stream_running)
  		period_elapsed = copy_data(channel, mbo);
  	most_put_mbo(mbo);
  	if (period_elapsed)
  		snd_pcm_period_elapsed(channel->substream);
  	return 0;
  }
  
  /**
   * audio_tx_completion - completion handler for tx channels
   * @iface: pointer to interface instance
   * @channel_id: channel index/ID
   *
   * This searches the channel that belongs to this combination of interface
   * pointer and channel ID and wakes a process sitting in the wait queue of
   * this channel.
   *
   * Returns 0 on success or error code otherwise.
   */
  static int audio_tx_completion(struct most_interface *iface, int channel_id)
  {
  	struct channel *channel = get_channel(iface, channel_id);
  
  	if (!channel)
  		return -EINVAL;
  
  	wake_up_interruptible(&channel->playback_waitq);
  	return 0;
  }
  
  /**
   * Initialization of the struct most_component
   */
  static struct most_component comp = {
  	.mod = THIS_MODULE,
  	.name = DRIVER_NAME,
  	.probe_channel = audio_probe_channel,
  	.disconnect_channel = audio_disconnect_channel,
  	.rx_completion = audio_rx_completion,
  	.tx_completion = audio_tx_completion,
  	.cfg_complete = audio_create_sound_card,
  };
  
  static int __init audio_init(void)
  {
  	int ret;
  
  	INIT_LIST_HEAD(&adpt_list);
  
  	ret = most_register_component(&comp);
  	if (ret) {
  		pr_err("Failed to register %s\n", comp.name);
  		return ret;
  	}
  	ret = most_register_configfs_subsys(&comp);
  	if (ret) {
  		pr_err("Failed to register %s configfs subsys\n", comp.name);
  		most_deregister_component(&comp);
  	}
  	return ret;
  }
  
  static void __exit audio_exit(void)
  {
  	most_deregister_configfs_subsys(&comp);
  	most_deregister_component(&comp);
  }
  
  module_init(audio_init);
  module_exit(audio_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
  MODULE_DESCRIPTION("Sound Component Module for Mostcore");
  