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/* SPDX-License-Identifier: GPL-2.0-only */
// Copyright (c) 2025 Šerif Rami <ramiserifpersia@gmail.com>
#ifndef __US144MKII_PCM_H
#define __US144MKII_PCM_H
#include "us144mkii.h"
/**
* var tascam_pcm_hw - Hardware capabilities for TASCAM US-144MKII PCM.
*
* Defines the supported PCM formats, rates, channels, and buffer/period sizes
* for the TASCAM US-144MKII audio interface.
*/
extern const struct snd_pcm_hardware tascam_pcm_hw;
/**
* var tascam_playback_ops - ALSA PCM operations for playback.
*
* This structure defines the callback functions for playback stream operations.
*/
extern const struct snd_pcm_ops tascam_playback_ops;
/**
* var tascam_capture_ops - ALSA PCM operations for capture.
*
* This structure defines the callback functions for capture stream operations.
*/
extern const struct snd_pcm_ops tascam_capture_ops;
/**
* playback_urb_complete() - Completion handler for playback isochronous URBs.
* @urb: the completed URB
*
* This function runs in interrupt context. It calculates the number of bytes
* to send in the next set of packets based on the feedback-driven clock,
* copies the audio data from the ALSA ring buffer, and resubmits the URB.
*/
void playback_urb_complete(struct urb *urb);
/**
* feedback_urb_complete() - Completion handler for feedback isochronous URBs.
* @urb: the completed URB
*
* This is the master clock for the driver. It runs in interrupt context.
* It reads the feedback value from the device, which indicates how many
* samples the device has consumed. This information is used to adjust the
* playback rate and to advance the capture stream pointer, keeping both
* streams in sync. It then calls snd_pcm_period_elapsed if necessary and
* resubmits itself.
*/
void feedback_urb_complete(struct urb *urb);
/**
* capture_urb_complete() - Completion handler for capture bulk URBs.
* @urb: the completed URB
*
* This function runs in interrupt context. It copies the received raw data
* into an intermediate ring buffer and then schedules the workqueue to process
* it. It then resubmits the URB to receive more data.
*/
void capture_urb_complete(struct urb *urb);
/**
* tascam_stop_pcm_work_handler() - Work handler to stop PCM streams.
* @work: Pointer to the work_struct.
*
* This function is scheduled to stop PCM streams (playback and capture)
* from a workqueue context, avoiding blocking operations in interrupt context.
*/
void tascam_stop_pcm_work_handler(struct work_struct *work);
/**
* tascam_init_pcm() - Initializes the ALSA PCM device.
* @pcm: Pointer to the ALSA PCM device to initialize.
*
* This function sets up the PCM operations, adds ALSA controls for routing
* and sample rate, and preallocates pages for the PCM buffer.
*
* Return: 0 on success, or a negative error code on failure.
*/
int tascam_init_pcm(struct snd_pcm *pcm);
/**
* us144mkii_configure_device_for_rate() - Set sample rate via USB control msgs
* @tascam: the tascam_card instance
* @rate: the target sample rate (e.g., 44100, 96000)
*
* This function sends a sequence of vendor-specific and UAC control messages
* to configure the device hardware for the specified sample rate.
*
* Return: 0 on success, or a negative error code on failure.
*/
int us144mkii_configure_device_for_rate(struct tascam_card *tascam, int rate);
/**
* process_playback_routing_us144mkii() - Apply playback routing matrix
* @tascam: The driver instance.
* @src_buffer: Buffer containing 4 channels of S24_3LE audio from ALSA.
* @dst_buffer: Buffer to be filled for the USB device.
* @frames: Number of frames to process.
*/
void process_playback_routing_us144mkii(struct tascam_card *tascam,
const u8 *src_buffer, u8 *dst_buffer,
size_t frames);
/**
* process_capture_routing_us144mkii() - Apply capture routing matrix
* @tascam: The driver instance.
* @decoded_block: Buffer containing 4 channels of S32LE decoded audio.
* @routed_block: Buffer to be filled for ALSA.
*/
void process_capture_routing_us144mkii(struct tascam_card *tascam,
const s32 *decoded_block,
s32 *routed_block);
/**
* tascam_pcm_hw_params() - Configures hardware parameters for PCM streams.
* @substream: The ALSA PCM substream.
* @params: The hardware parameters to apply.
*
* This function allocates pages for the PCM buffer and, for playback streams,
* selects the appropriate feedback patterns based on the requested sample rate.
* It also configures the device hardware for the selected sample rate if it
* has changed.
*
* Return: 0 on success, or a negative error code on failure.
*/
int tascam_pcm_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *params);
/**
* tascam_pcm_hw_free() - Frees hardware parameters for PCM streams.
* @substream: The ALSA PCM substream.
*
* This function is a stub for freeing hardware-related resources.
*
* Return: 0 on success.
*/
int tascam_pcm_hw_free(struct snd_pcm_substream *substream);
/**
* tascam_pcm_trigger() - Triggers the start or stop of PCM streams.
* @substream: The ALSA PCM substream.
* @cmd: The trigger command (e.g., SNDRV_PCM_TRIGGER_START).
*
* This function handles starting and stopping of playback and capture streams
* by submitting or killing the associated URBs.
*
* Return: 0 on success, or a negative error code on failure.
*/
int tascam_pcm_trigger(struct snd_pcm_substream *substream, int cmd);
/**
* tascam_capture_work_handler() - Deferred work for processing capture data.
* @work: the work_struct instance
*
* This function runs in a kernel thread context, not an IRQ context. It reads
* raw data from the capture ring buffer, decodes it, applies routing, and
* copies the final audio data into the ALSA capture ring buffer. This offloads
* the CPU-intensive decoding from the time-sensitive URB completion handlers.
*/
void tascam_capture_work_handler(struct work_struct *work);
#endif /* __US144MKII_PCM_H */
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