text: /* SPDX-License-Identifier: GPL-2.0+ */
  /*
   * virtio-snd: Virtio sound device
   * Copyright (C) 2021 OpenSynergy GmbH
   */
  #ifndef VIRTIO_SND_PCM_H
  #define VIRTIO_SND_PCM_H
  
  #include <linux/atomic.h>
  #include <linux/virtio_config.h>
  #include <sound/pcm.h>
  
  struct virtio_pcm;
  struct virtio_pcm_msg;
  
  /**
   * struct virtio_pcm_substream - VirtIO PCM substream.
   * @snd: VirtIO sound device.
   * @nid: Function group node identifier.
   * @sid: Stream identifier.
   * @direction: Stream data flow direction (SNDRV_PCM_STREAM_XXX).
   * @features: Stream VirtIO feature bit map (1 << VIRTIO_SND_PCM_F_XXX).
   * @substream: Kernel ALSA substream.
   * @hw: Kernel ALSA substream hardware descriptor.
   * @elapsed_period: Kernel work to handle the elapsed period state.
   * @lock: Spinlock that protects fields shared by interrupt handlers and
   *        substream operators.
   * @buffer_bytes: Current buffer size in bytes.
   * @hw_ptr: Substream hardware pointer value in bytes [0 ... buffer_bytes).
   * @xfer_enabled: Data transfer state (0 - off, 1 - on).
   * @xfer_xrun: Data underflow/overflow state (0 - no xrun, 1 - xrun).
   * @stopped: True if the substream is stopped and must be released on the device
   *           side.
   * @suspended: True if the substream is suspended and must be reconfigured on
   *             the device side at resume.
   * @msgs: Allocated I/O messages.
   * @nmsgs: Number of allocated I/O messages.
   * @msg_last_enqueued: Index of the last I/O message added to the virtqueue.
   * @msg_count: Number of pending I/O messages in the virtqueue.
   * @msg_empty: Notify when msg_count is zero.
   */
  struct virtio_pcm_substream {
  	struct virtio_snd *snd;
  	u32 nid;
  	u32 sid;
  	u32 direction;
  	u32 features;
  	struct snd_pcm_substream *substream;
  	struct snd_pcm_hardware hw;
  	struct work_struct elapsed_period;
  	spinlock_t lock;
  	size_t buffer_bytes;
  	size_t hw_ptr;
  	bool xfer_enabled;
  	bool xfer_xrun;
  	bool stopped;
  	bool suspended;
  	struct virtio_pcm_msg **msgs;
  	unsigned int nmsgs;
  	int msg_last_enqueued;
  	unsigned int msg_count;
  	wait_queue_head_t msg_empty;
  };
  
  /**
   * struct virtio_pcm_stream - VirtIO PCM stream.
   * @substreams: VirtIO substreams belonging to the stream.
   * @nsubstreams: Number of substreams.
   * @chmaps: Kernel channel maps belonging to the stream.
   * @nchmaps: Number of channel maps.
   */
  struct virtio_pcm_stream {
  	struct virtio_pcm_substream **substreams;
  	u32 nsubstreams;
  	struct snd_pcm_chmap_elem *chmaps;
  	u32 nchmaps;
  };
  
  /**
   * struct virtio_pcm - VirtIO PCM device.
   * @list: VirtIO PCM list entry.
   * @nid: Function group node identifier.
   * @pcm: Kernel PCM device.
   * @streams: VirtIO PCM streams (playback and capture).
   */
  struct virtio_pcm {
  	struct list_head list;
  	u32 nid;
  	struct snd_pcm *pcm;
  	struct virtio_pcm_stream streams[SNDRV_PCM_STREAM_LAST + 1];
  };
  
  extern const struct snd_pcm_ops virtsnd_pcm_ops;
  
  int virtsnd_pcm_validate(struct virtio_device *vdev);
  
  int virtsnd_pcm_parse_cfg(struct virtio_snd *snd);
  
  int virtsnd_pcm_build_devs(struct virtio_snd *snd);
  
  void virtsnd_pcm_event(struct virtio_snd *snd, struct virtio_snd_event *event);
  
  void virtsnd_pcm_tx_notify_cb(struct virtqueue *vqueue);
  
  void virtsnd_pcm_rx_notify_cb(struct virtqueue *vqueue);
  
  struct virtio_pcm *virtsnd_pcm_find(struct virtio_snd *snd, u32 nid);
  
  struct virtio_pcm *virtsnd_pcm_find_or_create(struct virtio_snd *snd, u32 nid);
  
  struct virtio_snd_msg *
  virtsnd_pcm_ctl_msg_alloc(struct virtio_pcm_substream *vss,
  			  unsigned int command, gfp_t gfp);
  
  int virtsnd_pcm_msg_alloc(struct virtio_pcm_substream *vss,
  			  unsigned int periods, unsigned int period_bytes);
  
  void virtsnd_pcm_msg_free(struct virtio_pcm_substream *vss);
  
  int virtsnd_pcm_msg_send(struct virtio_pcm_substream *vss);
  
  unsigned int virtsnd_pcm_msg_pending_num(struct virtio_pcm_substream *vss);
  
  #endif /* VIRTIO_SND_PCM_H */
  