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more modular refactoring

This commit is contained in:
serifpersia 2025-08-02 11:53:36 +02:00
parent 9f0c814b2d
commit 4a1008d070
7 changed files with 854 additions and 744 deletions
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4
Makefile
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@ -1,8 +1,8 @@
obj-m += snd-usb-us144mkii.o
snd-usb-us144mkii-y := us144mkii.o pcm.o midi.o controls.o
snd-usb-us144mkii-y := us144mkii.o pcm.o playback.o capture.o midi.o controls.o
all:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

278
capture.c Normal file
View File

@ -0,0 +1,278 @@
// SPDX-License-Identifier: GPL-2.0-only
// Copyright (c) 2025 serifpersia <ramiserifpersia@gmail.com>
#include "us144mkii.h"
#include "pcm.h"
/**
* tascam_capture_open() - Opens the PCM capture substream.
* @substream: The ALSA PCM substream to open.
*
* This function sets the hardware parameters for the capture substream
* and stores a reference to the substream in the driver's private data.
*
* Return: 0 on success.
*/
static int tascam_capture_open(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
substream->runtime->hw = tascam_pcm_hw;
tascam->capture_substream = substream;
atomic_set(&tascam->capture_active, 0);
return 0;
}
/**
* tascam_capture_close() - Closes the PCM capture substream.
* @substream: The ALSA PCM substream to close.
*
* This function clears the reference to the capture substream in the
* driver's private data.
*
* Return: 0 on success.
*/
static int tascam_capture_close(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
tascam->capture_substream = NULL;
return 0;
}
/**
* tascam_capture_prepare() - Prepares the PCM capture substream for use.
* @substream: The ALSA PCM substream to prepare.
*
* This function initializes capture-related counters and ring buffer pointers.
*
* Return: 0 on success.
*/
static int tascam_capture_prepare(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
tascam->driver_capture_pos = 0;
tascam->capture_frames_processed = 0;
tascam->last_capture_period_pos = 0;
tascam->capture_ring_buffer_read_ptr = 0;
tascam->capture_ring_buffer_write_ptr = 0;
return 0;
}
/**
* tascam_capture_pointer() - Returns the current capture pointer position.
* @substream: The ALSA PCM substream.
*
* This function returns the current position of the capture pointer within
* the ALSA ring buffer, in frames.
*
* Return: The current capture pointer position in frames.
*/
static snd_pcm_uframes_t tascam_capture_pointer(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
struct snd_pcm_runtime *runtime = substream->runtime;
u64 pos;
unsigned long flags;
if (!atomic_read(&tascam->capture_active))
return 0;
spin_lock_irqsave(&tascam->lock, flags);
pos = tascam->capture_frames_processed;
spin_unlock_irqrestore(&tascam->lock, flags);
return runtime ? pos % runtime->buffer_size : 0;
}
/**
* tascam_capture_ops - ALSA PCM operations for capture.
*
* This structure defines the callback functions for capture stream operations,
* including open, close, ioctl, hardware parameters, hardware free, prepare,
* trigger, and pointer.
*/
struct snd_pcm_ops tascam_capture_ops = {
.open = tascam_capture_open,
.close = tascam_capture_close,
.ioctl = snd_pcm_lib_ioctl,
.hw_params = tascam_pcm_hw_params,
.hw_free = tascam_pcm_hw_free,
.prepare = tascam_capture_prepare,
.trigger = tascam_pcm_trigger,
.pointer = tascam_capture_pointer,
};
/**
* decode_tascam_capture_block() - Decodes a raw 512-byte block from the device.
* @src_block: Pointer to the 512-byte raw source block.
* @dst_block: Pointer to the destination buffer for decoded audio frames.
*
* The device sends audio data in a complex, multiplexed format. This function
* demultiplexes the bits from the raw block into 8 frames of 4-channel,
* 24-bit audio (stored in 32-bit containers).
*/
static void decode_tascam_capture_block(const u8 *src_block, s32 *dst_block)
{
int frame, bit;
memset(dst_block, 0, FRAMES_PER_DECODE_BLOCK * DECODED_CHANNELS_PER_FRAME * DECODED_SAMPLE_SIZE);
for (frame = 0; frame < FRAMES_PER_DECODE_BLOCK; ++frame) {
const u8 *p_src_frame_base = src_block + frame * 64;
s32 *p_dst_frame = dst_block + frame * 4;
s32 ch[4] = {0};
for (bit = 0; bit < 24; ++bit) {
u8 byte1 = p_src_frame_base[bit];
u8 byte2 = p_src_frame_base[bit + 32];
ch[0] = (ch[0] << 1) | (byte1 & 1);
ch[2] = (ch[2] << 1) | ((byte1 >> 1) & 1);
ch[1] = (ch[1] << 1) | (byte2 & 1);
ch[3] = (ch[3] << 1) | ((byte2 >> 1) & 1);
}
/*
* The result is a 24-bit sample. Shift left by 8 to align it to
* the most significant bits of a 32-bit integer (S32_LE format).
*/
p_dst_frame[0] = ch[0] << 8;
p_dst_frame[1] = ch[1] << 8;
p_dst_frame[2] = ch[2] << 8;
p_dst_frame[3] = ch[3] << 8;
}
}
/**
* 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)
{
struct tascam_card *tascam = container_of(work, struct tascam_card, capture_work);
struct snd_pcm_substream *substream = tascam->capture_substream;
struct snd_pcm_runtime *runtime;
unsigned long flags;
u8 *raw_block = tascam->capture_decode_raw_block;
s32 *decoded_block = tascam->capture_decode_dst_block;
s32 *routed_block = tascam->capture_routing_buffer;
if (!substream || !substream->runtime)
return;
runtime = substream->runtime;
if (!raw_block || !decoded_block || !routed_block) {
dev_err(tascam->card->dev, "Capture decode/routing buffers not allocated!\n");
return;
}
while (atomic_read(&tascam->capture_active)) {
size_t write_ptr, read_ptr, available_data;
bool can_process;
spin_lock_irqsave(&tascam->lock, flags);
write_ptr = tascam->capture_ring_buffer_write_ptr;
read_ptr = tascam->capture_ring_buffer_read_ptr;
available_data = (write_ptr >= read_ptr) ? (write_ptr - read_ptr) : (CAPTURE_RING_BUFFER_SIZE - read_ptr + write_ptr);
can_process = (available_data >= RAW_BYTES_PER_DECODE_BLOCK);
if (can_process) {
size_t i;
for (i = 0; i < RAW_BYTES_PER_DECODE_BLOCK; i++)
raw_block[i] = tascam->capture_ring_buffer[(read_ptr + i) % CAPTURE_RING_BUFFER_SIZE];
tascam->capture_ring_buffer_read_ptr = (read_ptr + RAW_BYTES_PER_DECODE_BLOCK) % CAPTURE_RING_BUFFER_SIZE;
}
spin_unlock_irqrestore(&tascam->lock, flags);
if (!can_process)
break;
decode_tascam_capture_block(raw_block, decoded_block);
process_capture_routing_us144mkii(tascam, decoded_block, routed_block);
spin_lock_irqsave(&tascam->lock, flags);
if (atomic_read(&tascam->capture_active)) {
int f;
for (f = 0; f < FRAMES_PER_DECODE_BLOCK; ++f) {
u8 *dst_frame_start = runtime->dma_area + frames_to_bytes(runtime, tascam->driver_capture_pos);
s32 *routed_frame_start = routed_block + (f * NUM_CHANNELS);
int c;
for (c = 0; c < NUM_CHANNELS; c++) {
u8 *dst_channel = dst_frame_start + (c * BYTES_PER_SAMPLE);
s32 *src_channel_s32 = routed_frame_start + c;
memcpy(dst_channel, ((char *)src_channel_s32) + 1, 3);
}
tascam->driver_capture_pos = (tascam->driver_capture_pos + 1) % runtime->buffer_size;
}
}
spin_unlock_irqrestore(&tascam->lock, flags);
}
}
/**
* 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)
{
struct tascam_card *tascam = urb->context;
int ret;
unsigned long flags;
if (urb->status) {
if (urb->status != -ENOENT && urb->status != -ECONNRESET && urb->status != -ESHUTDOWN &&
urb->status != -ENODEV && urb->status != -EPROTO)
dev_err_ratelimited(tascam->card->dev, "Capture URB failed: %d\n", urb->status);
goto out;
}
if (!tascam || !atomic_read(&tascam->capture_active))
goto out;
if (urb->actual_length > 0) {
size_t i;
size_t write_ptr;
spin_lock_irqsave(&tascam->lock, flags);
write_ptr = tascam->capture_ring_buffer_write_ptr;
for (i = 0; i < urb->actual_length; i++) {
tascam->capture_ring_buffer[write_ptr] = ((u8 *)urb->transfer_buffer)[i];
write_ptr = (write_ptr + 1) % CAPTURE_RING_BUFFER_SIZE;
}
tascam->capture_ring_buffer_write_ptr = write_ptr;
spin_unlock_irqrestore(&tascam->lock, flags);
schedule_work(&tascam->capture_work);
}
usb_get_urb(urb);
usb_anchor_urb(urb, &tascam->capture_anchor);
ret = usb_submit_urb(urb, GFP_ATOMIC);
if (ret < 0) {
dev_err_ratelimited(tascam->card->dev, "Failed to resubmit capture URB: %d\n", ret);
usb_unanchor_urb(urb);
usb_put_urb(urb);
}
out:
usb_put_urb(urb);
}

690
pcm.c
View File

@ -2,8 +2,7 @@
// Copyright (c) 2025 serifpersia <ramiserifpersia@gmail.com>
#include "us144mkii.h"
#include "pcm.h"
/**
* @brief Rate-to-Packet Fixing Data (Verified)
@ -69,9 +68,9 @@ const struct snd_pcm_hardware tascam_pcm_hw = {
* @dst_buffer: Buffer to be filled for the USB device.
* @frames: Number of frames to process.
*/
static void process_playback_routing_us144mkii(struct tascam_card *tascam,
const u8 *src_buffer,
u8 *dst_buffer, size_t frames)
void process_playback_routing_us144mkii(struct tascam_card *tascam,
const u8 *src_buffer,
u8 *dst_buffer, size_t frames)
{
size_t f;
const u8 *src_12, *src_34;
@ -103,9 +102,9 @@ static void process_playback_routing_us144mkii(struct tascam_card *tascam,
* @decoded_block: Buffer containing 4 channels of S32LE decoded audio.
* @routed_block: Buffer to be filled for ALSA.
*/
static void process_capture_routing_us144mkii(struct tascam_card *tascam,
const s32 *decoded_block,
s32 *routed_block)
void process_capture_routing_us144mkii(struct tascam_card *tascam,
const s32 *decoded_block,
s32 *routed_block)
{
int f;
const s32 *src_frame;
@ -135,82 +134,6 @@ static void process_capture_routing_us144mkii(struct tascam_card *tascam,
}
}
/**
* tascam_playback_open() - Opens the PCM playback substream.
* @substream: The ALSA PCM substream to open.
*
* This function sets the hardware parameters for the playback substream
* and stores a reference to the substream in the driver's private data.
*
* Return: 0 on success.
*/
static int tascam_playback_open(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
substream->runtime->hw = tascam_pcm_hw;
tascam->playback_substream = substream;
atomic_set(&tascam->playback_active, 0);
return 0;
}
/**
* tascam_capture_open() - Opens the PCM capture substream.
* @substream: The ALSA PCM substream to open.
*
* This function sets the hardware parameters for the capture substream
* and stores a reference to the substream in the driver's private data.
*
* Return: 0 on success.
*/
static int tascam_capture_open(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
substream->runtime->hw = tascam_pcm_hw;
tascam->capture_substream = substream;
atomic_set(&tascam->capture_active, 0);
return 0;
}
/**
* tascam_playback_close() - Closes the PCM playback substream.
* @substream: The ALSA PCM substream to close.
*
* This function clears the reference to the playback substream in the
* driver's private data.
*
* Return: 0 on success.
*/
static int tascam_playback_close(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
tascam->playback_substream = NULL;
return 0;
}
/**
* tascam_capture_close() - Closes the PCM capture substream.
* @substream: The ALSA PCM substream to close.
*
* This function clears the reference to the capture substream in the
* driver's private data.
*
* Return: 0 on success.
*/
static int tascam_capture_close(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
tascam->capture_substream = NULL;
return 0;
}
/**
* us144mkii_configure_device_for_rate() - Set sample rate via USB control msgs
* @tascam: the tascam_card instance
@ -311,7 +234,7 @@ fail:
*
* Return: 0 on success, or a negative error code on failure.
*/
static int tascam_pcm_hw_params(struct snd_pcm_substream *substream,
int tascam_pcm_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *params)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
@ -369,97 +292,12 @@ static int tascam_pcm_hw_params(struct snd_pcm_substream *substream,
*
* Return: 0 on success.
*/
static int tascam_pcm_hw_free(struct snd_pcm_substream *substream)
int tascam_pcm_hw_free(struct snd_pcm_substream *substream)
{
return snd_pcm_lib_free_pages(substream);
}
/**
* tascam_playback_prepare() - Prepares the PCM playback substream for use.
* @substream: The ALSA PCM substream to prepare.
*
* This function initializes playback-related counters and flags, and configures
* the playback URBs with appropriate packet sizes based on the nominal frame
* rate and feedback accumulator.
*
* Return: 0 on success.
*/
static int tascam_playback_prepare(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
struct snd_pcm_runtime *runtime = substream->runtime;
int i, u;
size_t nominal_frames_per_packet, nominal_bytes_per_packet;
size_t total_bytes_in_urb;
unsigned int feedback_packets;
tascam->driver_playback_pos = 0;
tascam->playback_frames_consumed = 0;
tascam->last_period_pos = 0;
tascam->feedback_pattern_in_idx = 0;
tascam->feedback_pattern_out_idx = 0;
tascam->feedback_synced = false;
tascam->feedback_consecutive_errors = 0;
tascam->feedback_urb_skip_count = NUM_FEEDBACK_URBS;
nominal_frames_per_packet = runtime->rate / 8000;
for (i = 0; i < FEEDBACK_ACCUMULATOR_SIZE; i++)
tascam->feedback_accumulator_pattern[i] = nominal_frames_per_packet;
feedback_packets = 1;
for (i = 0; i < NUM_FEEDBACK_URBS; i++) {
struct urb *f_urb = tascam->feedback_urbs[i];
int j;
f_urb->number_of_packets = feedback_packets;
f_urb->transfer_buffer_length = feedback_packets * FEEDBACK_PACKET_SIZE;
for (j = 0; j < feedback_packets; j++) {
f_urb->iso_frame_desc[j].offset = j * FEEDBACK_PACKET_SIZE;
f_urb->iso_frame_desc[j].length = FEEDBACK_PACKET_SIZE;
}
}
nominal_bytes_per_packet = nominal_frames_per_packet * BYTES_PER_FRAME;
total_bytes_in_urb = nominal_bytes_per_packet * PLAYBACK_URB_PACKETS;
for (u = 0; u < NUM_PLAYBACK_URBS; u++) {
struct urb *urb = tascam->playback_urbs[u];
memset(urb->transfer_buffer, 0, tascam->playback_urb_alloc_size);
urb->transfer_buffer_length = total_bytes_in_urb;
urb->number_of_packets = PLAYBACK_URB_PACKETS;
for (i = 0; i < PLAYBACK_URB_PACKETS; i++) {
urb->iso_frame_desc[i].offset = i * nominal_bytes_per_packet;
urb->iso_frame_desc[i].length = nominal_bytes_per_packet;
}
}
return 0;
}
/**
* tascam_capture_prepare() - Prepares the PCM capture substream for use.
* @substream: The ALSA PCM substream to prepare.
*
* This function initializes capture-related counters and ring buffer pointers.
*
* Return: 0 on success.
*/
static int tascam_capture_prepare(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
tascam->driver_capture_pos = 0;
tascam->capture_frames_processed = 0;
tascam->last_capture_period_pos = 0;
tascam->capture_ring_buffer_read_ptr = 0;
tascam->capture_ring_buffer_write_ptr = 0;
return 0;
}
/**
* tascam_pcm_trigger() - Triggers the start or stop of PCM streams.
* @substream: The ALSA PCM substream.
@ -471,7 +309,7 @@ static int tascam_capture_prepare(struct snd_pcm_substream *substream)
*
* Return: 0 on success, or a negative error code on failure.
*/
static int tascam_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
int tascam_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
unsigned long flags;
@ -507,7 +345,7 @@ static int tascam_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
if (do_start) {
if (atomic_read(&tascam->active_urbs) > 0) {
dev_warn(tascam->card->dev, "Cannot start, URBs still active.\n");
dev_WARN(tascam->card->dev, "Cannot start, URBs still active.\n");
return -EAGAIN;
}
@ -557,506 +395,6 @@ start_rollback:
return err;
}
/**
* tascam_playback_pointer() - Returns the current playback pointer position.
* @substream: The ALSA PCM substream.
*
* This function returns the current position of the playback pointer within
* the ALSA ring buffer, in frames.
*
* Return: The current playback pointer position in frames.
*/
static snd_pcm_uframes_t tascam_playback_pointer(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
struct snd_pcm_runtime *runtime = substream->runtime;
u64 pos;
unsigned long flags;
if (!atomic_read(&tascam->playback_active))
return 0;
spin_lock_irqsave(&tascam->lock, flags);
pos = tascam->playback_frames_consumed;
spin_unlock_irqrestore(&tascam->lock, flags);
return runtime ? pos % runtime->buffer_size : 0;
}
static snd_pcm_uframes_t tascam_capture_pointer(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
struct snd_pcm_runtime *runtime = substream->runtime;
u64 pos;
unsigned long flags;
if (!atomic_read(&tascam->capture_active))
return 0;
spin_lock_irqsave(&tascam->lock, flags);
pos = tascam->capture_frames_processed;
spin_unlock_irqrestore(&tascam->lock, flags);
return runtime ? pos % runtime->buffer_size : 0;
}
/**
* tascam_playback_ops - ALSA PCM operations for playback.
*
* This structure defines the callback functions for playback stream operations,
* including open, close, ioctl, hardware parameters, hardware free, prepare,
* trigger, and pointer.
*/
static struct snd_pcm_ops tascam_playback_ops = {
.open = tascam_playback_open,
.close = tascam_playback_close,
.ioctl = snd_pcm_lib_ioctl,
.hw_params = tascam_pcm_hw_params,
.hw_free = tascam_pcm_hw_free,
.prepare = tascam_playback_prepare,
.trigger = tascam_pcm_trigger,
.pointer = tascam_playback_pointer,
};
/**
* tascam_capture_ops - ALSA PCM operations for capture.
*
* This structure defines the callback functions for capture stream operations,
* including open, close, ioctl, hardware parameters, hardware free, prepare,
* trigger, and pointer.
*/
static struct snd_pcm_ops tascam_capture_ops = {
.open = tascam_capture_open,
.close = tascam_capture_close,
.ioctl = snd_pcm_lib_ioctl,
.hw_params = tascam_pcm_hw_params,
.hw_free = tascam_pcm_hw_free,
.prepare = tascam_capture_prepare,
.trigger = tascam_pcm_trigger,
.pointer = tascam_capture_pointer,
};
/**
* 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 (applying routing), and
* resubmits the URB.
*/
void playback_urb_complete(struct urb *urb)
{
struct tascam_card *tascam = urb->context;
struct snd_pcm_substream *substream;
struct snd_pcm_runtime *runtime;
unsigned long flags;
u8 *src_buf, *dst_buf;
size_t total_bytes_for_urb = 0;
snd_pcm_uframes_t offset_frames;
snd_pcm_uframes_t frames_to_copy;
int ret, i;
if (urb->status) {
if (urb->status != -ENOENT && urb->status != -ECONNRESET && urb->status != -ESHUTDOWN &&
urb->status != -ENODEV)
dev_err_ratelimited(tascam->card->dev, "Playback URB failed: %d\n", urb->status);
goto out;
}
if (!tascam || !atomic_read(&tascam->playback_active))
goto out;
substream = tascam->playback_substream;
if (!substream || !substream->runtime)
goto out;
runtime = substream->runtime;
spin_lock_irqsave(&tascam->lock, flags);
for (i = 0; i < urb->number_of_packets; i++) {
unsigned int frames_for_packet;
size_t bytes_for_packet;
if (tascam->feedback_synced) {
frames_for_packet = tascam->feedback_accumulator_pattern[tascam->feedback_pattern_out_idx];
tascam->feedback_pattern_out_idx = (tascam->feedback_pattern_out_idx + 1) % FEEDBACK_ACCUMULATOR_SIZE;
} else {
frames_for_packet = runtime->rate / 8000;
}
bytes_for_packet = frames_for_packet * BYTES_PER_FRAME;
urb->iso_frame_desc[i].offset = total_bytes_for_urb;
urb->iso_frame_desc[i].length = bytes_for_packet;
total_bytes_for_urb += bytes_for_packet;
}
urb->transfer_buffer_length = total_bytes_for_urb;
offset_frames = tascam->driver_playback_pos;
frames_to_copy = bytes_to_frames(runtime, total_bytes_for_urb);
tascam->driver_playback_pos = (offset_frames + frames_to_copy) % runtime->buffer_size;
spin_unlock_irqrestore(&tascam->lock, flags);
if (total_bytes_for_urb > 0) {
src_buf = runtime->dma_area + frames_to_bytes(runtime, offset_frames);
dst_buf = tascam->playback_routing_buffer;
/* Handle ring buffer wrap-around */
if (offset_frames + frames_to_copy > runtime->buffer_size) {
size_t first_chunk_bytes = frames_to_bytes(runtime, runtime->buffer_size - offset_frames);
size_t second_chunk_bytes = total_bytes_for_urb - first_chunk_bytes;
memcpy(dst_buf, src_buf, first_chunk_bytes);
memcpy(dst_buf + first_chunk_bytes, runtime->dma_area, second_chunk_bytes);
} else {
memcpy(dst_buf, src_buf, total_bytes_for_urb);
}
/* Apply routing to the contiguous data in our routing buffer */
process_playback_routing_us144mkii(tascam, dst_buf, dst_buf, frames_to_copy);
memcpy(urb->transfer_buffer, dst_buf, total_bytes_for_urb);
}
urb->dev = tascam->dev;
usb_get_urb(urb);
usb_anchor_urb(urb, &tascam->playback_anchor);
ret = usb_submit_urb(urb, GFP_ATOMIC);
if (ret < 0) {
dev_err_ratelimited(tascam->card->dev, "Failed to resubmit playback URB: %d\n", ret);
usb_unanchor_urb(urb);
usb_put_urb(urb);
}
out:
usb_put_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)
{
struct tascam_card *tascam = urb->context;
struct snd_pcm_substream *playback_ss, *capture_ss;
struct snd_pcm_runtime *playback_rt, *capture_rt;
unsigned long flags;
u64 total_frames_in_urb = 0;
int ret, p;
unsigned int old_in_idx, new_in_idx;
bool playback_period_elapsed = false;
bool capture_period_elapsed = false;
if (urb->status) {
if (urb->status != -ENOENT && urb->status != -ECONNRESET && urb->status != -ESHUTDOWN &&
urb->status != -ENODEV)
dev_err_ratelimited(tascam->card->dev, "Feedback URB failed: %d\n", urb->status);
goto out;
}
if (!tascam || !atomic_read(&tascam->playback_active))
goto out;
playback_ss = tascam->playback_substream;
if (!playback_ss || !playback_ss->runtime)
goto out;
playback_rt = playback_ss->runtime;
capture_ss = tascam->capture_substream;
capture_rt = capture_ss ? capture_ss->runtime : NULL;
spin_lock_irqsave(&tascam->lock, flags);
if (tascam->feedback_urb_skip_count > 0) {
tascam->feedback_urb_skip_count--;
goto unlock_and_continue;
}
old_in_idx = tascam->feedback_pattern_in_idx;
for (p = 0; p < urb->number_of_packets; p++) {
u8 feedback_value = 0;
const unsigned int *pattern;
bool packet_ok = (urb->iso_frame_desc[p].status == 0 &&
urb->iso_frame_desc[p].actual_length >= 1);
if (packet_ok)
feedback_value = *((u8 *)urb->transfer_buffer + urb->iso_frame_desc[p].offset);
if (packet_ok && feedback_value >= tascam->feedback_base_value &&
feedback_value <= tascam->feedback_max_value) {
pattern = tascam->feedback_patterns[feedback_value - tascam->feedback_base_value];
tascam->feedback_consecutive_errors = 0;
int i;
for (i = 0; i < 8; i++) {
unsigned int in_idx = (tascam->feedback_pattern_in_idx + i) % FEEDBACK_ACCUMULATOR_SIZE;
tascam->feedback_accumulator_pattern[in_idx] = pattern[i];
total_frames_in_urb += pattern[i];
}
} else {
unsigned int nominal_frames = playback_rt->rate / 8000;
int i;
if (tascam->feedback_synced) {
tascam->feedback_consecutive_errors++;
if (tascam->feedback_consecutive_errors > FEEDBACK_SYNC_LOSS_THRESHOLD) {
dev_err(tascam->card->dev, "Fatal: Feedback sync lost. Stopping stream.\n");
if (playback_ss)
snd_pcm_stop(playback_ss, SNDRV_PCM_STATE_XRUN);
if (capture_ss)
snd_pcm_stop(capture_ss, SNDRV_PCM_STATE_XRUN);
tascam->feedback_synced = false;
goto unlock_and_continue;
}
}
for (i = 0; i < 8; i++) {
unsigned int in_idx = (tascam->feedback_pattern_in_idx + i) % FEEDBACK_ACCUMULATOR_SIZE;
tascam->feedback_accumulator_pattern[in_idx] = nominal_frames;
total_frames_in_urb += nominal_frames;
}
}
tascam->feedback_pattern_in_idx = (tascam->feedback_pattern_in_idx + 8) % FEEDBACK_ACCUMULATOR_SIZE;
}
new_in_idx = tascam->feedback_pattern_in_idx;
if (!tascam->feedback_synced) {
unsigned int out_idx = tascam->feedback_pattern_out_idx;
bool is_ahead = (new_in_idx - out_idx) % FEEDBACK_ACCUMULATOR_SIZE < (FEEDBACK_ACCUMULATOR_SIZE / 2);
bool was_behind = (old_in_idx - out_idx) % FEEDBACK_ACCUMULATOR_SIZE >= (FEEDBACK_ACCUMULATOR_SIZE / 2);
if (is_ahead && was_behind) {
dev_dbg(tascam->card->dev, "Sync Acquired! (in: %u, out: %u)\n", new_in_idx, out_idx);
tascam->feedback_synced = true;
tascam->feedback_consecutive_errors = 0;
}
}
if (total_frames_in_urb > 0) {
tascam->playback_frames_consumed += total_frames_in_urb;
if (atomic_read(&tascam->capture_active))
tascam->capture_frames_processed += total_frames_in_urb;
}
if (playback_rt->period_size > 0) {
u64 current_period = div_u64(tascam->playback_frames_consumed, playback_rt->period_size);
if (current_period > tascam->last_period_pos) {
tascam->last_period_pos = current_period;
playback_period_elapsed = true;
}
}
if (atomic_read(&tascam->capture_active) && capture_rt && capture_rt->period_size > 0) {
u64 current_capture_period = div_u64(tascam->capture_frames_processed, capture_rt->period_size);
if (current_capture_period > tascam->last_capture_period_pos) {
tascam->last_capture_period_pos = current_capture_period;
capture_period_elapsed = true;
}
}
unlock_and_continue:
spin_unlock_irqrestore(&tascam->lock, flags);
if (playback_period_elapsed)
snd_pcm_period_elapsed(playback_ss);
if (capture_period_elapsed)
snd_pcm_period_elapsed(capture_ss);
urb->dev = tascam->dev;
usb_get_urb(urb);
usb_anchor_urb(urb, &tascam->feedback_anchor);
ret = usb_submit_urb(urb, GFP_ATOMIC);
if (ret < 0) {
dev_err_ratelimited(tascam->card->dev, "Failed to resubmit feedback URB: %d\n", ret);
usb_unanchor_urb(urb);
usb_put_urb(urb);
}
out:
usb_put_urb(urb);
}
/**
* decode_tascam_capture_block() - Decodes a raw 512-byte block from the device.
* @src_block: Pointer to the 512-byte raw source block.
* @dst_block: Pointer to the destination buffer for decoded audio frames.
*
* The device sends audio data in a complex, multiplexed format. This function
* demultiplexes the bits from the raw block into 8 frames of 4-channel,
* 24-bit audio (stored in 32-bit containers).
*/
static void decode_tascam_capture_block(const u8 *src_block, s32 *dst_block)
{
int frame, bit;
memset(dst_block, 0, FRAMES_PER_DECODE_BLOCK * DECODED_CHANNELS_PER_FRAME * DECODED_SAMPLE_SIZE);
for (frame = 0; frame < FRAMES_PER_DECODE_BLOCK; ++frame) {
const u8 *p_src_frame_base = src_block + frame * 64;
s32 *p_dst_frame = dst_block + frame * 4;
s32 ch[4] = {0};
for (bit = 0; bit < 24; ++bit) {
u8 byte1 = p_src_frame_base[bit];
u8 byte2 = p_src_frame_base[bit + 32];
ch[0] = (ch[0] << 1) | (byte1 & 1);
ch[2] = (ch[2] << 1) | ((byte1 >> 1) & 1);
ch[1] = (ch[1] << 1) | (byte2 & 1);
ch[3] = (ch[3] << 1) | ((byte2 >> 1) & 1);
}
/*
* The result is a 24-bit sample. Shift left by 8 to align it to
* the most significant bits of a 32-bit integer (S32_LE format).
*/
p_dst_frame[0] = ch[0] << 8;
p_dst_frame[1] = ch[1] << 8;
p_dst_frame[2] = ch[2] << 8;
p_dst_frame[3] = ch[3] << 8;
}
}
/**
* 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.
*/
static void tascam_capture_work_handler(struct work_struct *work)
{
struct tascam_card *tascam = container_of(work, struct tascam_card, capture_work);
struct snd_pcm_substream *substream = tascam->capture_substream;
struct snd_pcm_runtime *runtime;
unsigned long flags;
u8 *raw_block = tascam->capture_decode_raw_block;
s32 *decoded_block = tascam->capture_decode_dst_block;
s32 *routed_block = tascam->capture_routing_buffer;
if (!substream || !substream->runtime)
return;
runtime = substream->runtime;
if (!raw_block || !decoded_block || !routed_block) {
dev_err(tascam->card->dev, "Capture decode/routing buffers not allocated!\n");
return;
}
while (atomic_read(&tascam->capture_active)) {
size_t write_ptr, read_ptr, available_data;
bool can_process;
spin_lock_irqsave(&tascam->lock, flags);
write_ptr = tascam->capture_ring_buffer_write_ptr;
read_ptr = tascam->capture_ring_buffer_read_ptr;
available_data = (write_ptr >= read_ptr) ? (write_ptr - read_ptr) : (CAPTURE_RING_BUFFER_SIZE - read_ptr + write_ptr);
can_process = (available_data >= RAW_BYTES_PER_DECODE_BLOCK);
if (can_process) {
size_t i;
for (i = 0; i < RAW_BYTES_PER_DECODE_BLOCK; i++)
raw_block[i] = tascam->capture_ring_buffer[(read_ptr + i) % CAPTURE_RING_BUFFER_SIZE];
tascam->capture_ring_buffer_read_ptr = (read_ptr + RAW_BYTES_PER_DECODE_BLOCK) % CAPTURE_RING_BUFFER_SIZE;
}
spin_unlock_irqrestore(&tascam->lock, flags);
if (!can_process)
break;
decode_tascam_capture_block(raw_block, decoded_block);
process_capture_routing_us144mkii(tascam, decoded_block, routed_block);
spin_lock_irqsave(&tascam->lock, flags);
if (atomic_read(&tascam->capture_active)) {
int f;
for (f = 0; f < FRAMES_PER_DECODE_BLOCK; ++f) {
u8 *dst_frame_start = runtime->dma_area + frames_to_bytes(runtime, tascam->driver_capture_pos);
s32 *routed_frame_start = routed_block + (f * NUM_CHANNELS);
int c;
for (c = 0; c < NUM_CHANNELS; c++) {
u8 *dst_channel = dst_frame_start + (c * BYTES_PER_SAMPLE);
s32 *src_channel_s32 = routed_frame_start + c;
memcpy(dst_channel, ((char *)src_channel_s32) + 1, 3);
}
tascam->driver_capture_pos = (tascam->driver_capture_pos + 1) % runtime->buffer_size;
}
}
spin_unlock_irqrestore(&tascam->lock, flags);
}
}
/**
* 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)
{
struct tascam_card *tascam = urb->context;
int ret;
unsigned long flags;
if (urb->status) {
if (urb->status != -ENOENT && urb->status != -ECONNRESET && urb->status != -ESHUTDOWN &&
urb->status != -ENODEV && urb->status != -EPROTO)
dev_err_ratelimited(tascam->card->dev, "Capture URB failed: %d\n", urb->status);
goto out;
}
if (!tascam || !atomic_read(&tascam->capture_active))
goto out;
if (urb->actual_length > 0) {
size_t i;
size_t write_ptr;
spin_lock_irqsave(&tascam->lock, flags);
write_ptr = tascam->capture_ring_buffer_write_ptr;
for (i = 0; i < urb->actual_length; i++) {
tascam->capture_ring_buffer[write_ptr] = ((u8 *)urb->transfer_buffer)[i];
write_ptr = (write_ptr + 1) % CAPTURE_RING_BUFFER_SIZE;
}
tascam->capture_ring_buffer_write_ptr = write_ptr;
spin_unlock_irqrestore(&tascam->lock, flags);
schedule_work(&tascam->capture_work);
}
usb_get_urb(urb);
usb_anchor_urb(urb, &tascam->capture_anchor);
ret = usb_submit_urb(urb, GFP_ATOMIC);
if (ret < 0) {
dev_err_ratelimited(tascam->card->dev, "Failed to resubmit capture URB: %d\n", ret);
usb_unanchor_urb(urb);
usb_put_urb(urb);
}
out:
usb_put_urb(urb);
}
/**
* tascam_init_pcm() - Initializes the ALSA PCM device.
* @pcm: Pointer to the ALSA PCM device to initialize.
@ -1074,9 +412,9 @@ int tascam_init_pcm(struct snd_pcm *pcm)
snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &tascam_playback_ops);
snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &tascam_capture_ops);
snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
tascam->dev->dev.parent,
64 * 1024,
tascam_pcm_hw.buffer_bytes_max);
tascam->dev->dev.parent,
64 * 1024,
tascam_pcm_hw.buffer_bytes_max);
INIT_WORK(&tascam->capture_work, tascam_capture_work_handler);

157
pcm.h Normal file
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@ -0,0 +1,157 @@
/* SPDX-License-Identifier: GPL-2.0-only */
// Copyright (c) 2025 serifpersia <ramiserifpersia@gmail.com>
#ifndef __US144MKII_PCM_H
#define __US144MKII_PCM_H
#include "us144mkii.h"
/**
* 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;
/**
* tascam_playback_ops - ALSA PCM operations for playback.
*
* This structure defines the callback functions for playback stream operations,
* including open, close, ioctl, hardware parameters, hardware free, prepare,
* trigger, and pointer.
*/
extern struct snd_pcm_ops tascam_playback_ops;
/**
* tascam_capture_ops - ALSA PCM operations for capture.
*
* This structure defines the callback functions for capture stream operations,
* including open, close, ioctl, hardware parameters, hardware free, prepare,
* trigger, and pointer.
*/
extern 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 (applying routing), 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_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 frees the pages allocated for the PCM buffer.
*
* 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, SNDRV_PCM_TRIGGER_STOP).
*
* This function handles starting and stopping of playback and capture streams
* by submitting or killing the associated URBs. It ensures that both streams
* are started/stopped together.
*
* 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 */

400
playback.c Normal file
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@ -0,0 +1,400 @@
// SPDX-License-Identifier: GPL-2.0-only
// Copyright (c) 2025 serifpersia <ramiserifpersia@gmail.com>
#include "us144mkii.h"
#include "pcm.h"
/**
* tascam_playback_open() - Opens the PCM playback substream.
* @substream: The ALSA PCM substream to open.
*
* This function sets the hardware parameters for the playback substream
* and stores a reference to the substream in the driver's private data.
*
* Return: 0 on success.
*/
static int tascam_playback_open(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
substream->runtime->hw = tascam_pcm_hw;
tascam->playback_substream = substream;
atomic_set(&tascam->playback_active, 0);
return 0;
}
/**
* tascam_playback_close() - Closes the PCM playback substream.
* @substream: The ALSA PCM substream to close.
*
* This function clears the reference to the playback substream in the
* driver's private data.
*
* Return: 0 on success.
*/
static int tascam_playback_close(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
tascam->playback_substream = NULL;
return 0;
}
/**
* tascam_playback_prepare() - Prepares the PCM playback substream for use.
* @substream: The ALSA PCM substream to prepare.
*
* This function initializes playback-related counters and flags, and configures
* the playback URBs with appropriate packet sizes based on the nominal frame
* rate and feedback accumulator.
*
* Return: 0 on success.
*/
static int tascam_playback_prepare(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
struct snd_pcm_runtime *runtime = substream->runtime;
int i, u;
size_t nominal_frames_per_packet, nominal_bytes_per_packet;
size_t total_bytes_in_urb;
unsigned int feedback_packets;
tascam->driver_playback_pos = 0;
tascam->playback_frames_consumed = 0;
tascam->last_period_pos = 0;
tascam->feedback_pattern_in_idx = 0;
tascam->feedback_pattern_out_idx = 0;
tascam->feedback_synced = false;
tascam->feedback_consecutive_errors = 0;
tascam->feedback_urb_skip_count = NUM_FEEDBACK_URBS;
nominal_frames_per_packet = runtime->rate / 8000;
for (i = 0; i < FEEDBACK_ACCUMULATOR_SIZE; i++)
tascam->feedback_accumulator_pattern[i] = nominal_frames_per_packet;
feedback_packets = 1;
for (i = 0; i < NUM_FEEDBACK_URBS; i++) {
struct urb *f_urb = tascam->feedback_urbs[i];
int j;
f_urb->number_of_packets = feedback_packets;
f_urb->transfer_buffer_length = feedback_packets * FEEDBACK_PACKET_SIZE;
for (j = 0; j < feedback_packets; j++) {
f_urb->iso_frame_desc[j].offset = j * FEEDBACK_PACKET_SIZE;
f_urb->iso_frame_desc[j].length = FEEDBACK_PACKET_SIZE;
}
}
nominal_bytes_per_packet = nominal_frames_per_packet * BYTES_PER_FRAME;
total_bytes_in_urb = nominal_bytes_per_packet * PLAYBACK_URB_PACKETS;
for (u = 0; u < NUM_PLAYBACK_URBS; u++) {
struct urb *urb = tascam->playback_urbs[u];
memset(urb->transfer_buffer, 0, tascam->playback_urb_alloc_size);
urb->transfer_buffer_length = total_bytes_in_urb;
urb->number_of_packets = PLAYBACK_URB_PACKETS;
for (i = 0; i < PLAYBACK_URB_PACKETS; i++) {
urb->iso_frame_desc[i].offset = i * nominal_bytes_per_packet;
urb->iso_frame_desc[i].length = nominal_bytes_per_packet;
}
}
return 0;
}
/**
* tascam_playback_pointer() - Returns the current playback pointer position.
* @substream: The ALSA PCM substream.
*
* This function returns the current position of the playback pointer within
* the ALSA ring buffer, in frames.
*
* Return: The current playback pointer position in frames.
*/
static snd_pcm_uframes_t tascam_playback_pointer(struct snd_pcm_substream *substream)
{
struct tascam_card *tascam = snd_pcm_substream_chip(substream);
struct snd_pcm_runtime *runtime = substream->runtime;
u64 pos;
unsigned long flags;
if (!atomic_read(&tascam->playback_active))
return 0;
spin_lock_irqsave(&tascam->lock, flags);
pos = tascam->playback_frames_consumed;
spin_unlock_irqrestore(&tascam->lock, flags);
return runtime ? pos % runtime->buffer_size : 0;
}
/**
* tascam_playback_ops - ALSA PCM operations for playback.
*
* This structure defines the callback functions for playback stream operations,
* including open, close, ioctl, hardware parameters, hardware free, prepare,
* trigger, and pointer.
*/
struct snd_pcm_ops tascam_playback_ops = {
.open = tascam_playback_open,
.close = tascam_playback_close,
.ioctl = snd_pcm_lib_ioctl,
.hw_params = tascam_pcm_hw_params,
.hw_free = tascam_pcm_hw_free,
.prepare = tascam_playback_prepare,
.trigger = tascam_pcm_trigger,
.pointer = tascam_playback_pointer,
};
/**
* 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 (applying routing), and
* resubmits the URB.
*/
void playback_urb_complete(struct urb *urb)
{
struct tascam_card *tascam = urb->context;
struct snd_pcm_substream *substream;
struct snd_pcm_runtime *runtime;
unsigned long flags;
u8 *src_buf, *dst_buf;
size_t total_bytes_for_urb = 0;
snd_pcm_uframes_t offset_frames;
snd_pcm_uframes_t frames_to_copy;
int ret, i;
if (urb->status) {
if (urb->status != -ENOENT && urb->status != -ECONNRESET && urb->status != -ESHUTDOWN &&
urb->status != -ENODEV)
dev_err_ratelimited(tascam->card->dev, "Playback URB failed: %d\n", urb->status);
goto out;
}
if (!tascam || !atomic_read(&tascam->playback_active))
goto out;
substream = tascam->playback_substream;
if (!substream || !substream->runtime)
goto out;
runtime = substream->runtime;
spin_lock_irqsave(&tascam->lock, flags);
for (i = 0; i < urb->number_of_packets; i++) {
unsigned int frames_for_packet;
size_t bytes_for_packet;
if (tascam->feedback_synced) {
frames_for_packet = tascam->feedback_accumulator_pattern[tascam->feedback_pattern_out_idx];
tascam->feedback_pattern_out_idx = (tascam->feedback_pattern_out_idx + 1) % FEEDBACK_ACCUMULATOR_SIZE;
} else {
frames_for_packet = runtime->rate / 8000;
}
bytes_for_packet = frames_for_packet * BYTES_PER_FRAME;
urb->iso_frame_desc[i].offset = total_bytes_for_urb;
urb->iso_frame_desc[i].length = bytes_for_packet;
total_bytes_for_urb += bytes_for_packet;
}
urb->transfer_buffer_length = total_bytes_for_urb;
offset_frames = tascam->driver_playback_pos;
frames_to_copy = bytes_to_frames(runtime, total_bytes_for_urb);
tascam->driver_playback_pos = (offset_frames + frames_to_copy) % runtime->buffer_size;
spin_unlock_irqrestore(&tascam->lock, flags);
if (total_bytes_for_urb > 0) {
src_buf = runtime->dma_area + frames_to_bytes(runtime, offset_frames);
dst_buf = tascam->playback_routing_buffer;
/* Handle ring buffer wrap-around */
if (offset_frames + frames_to_copy > runtime->buffer_size) {
size_t first_chunk_bytes = frames_to_bytes(runtime, runtime->buffer_size - offset_frames);
size_t second_chunk_bytes = total_bytes_for_urb - first_chunk_bytes;
memcpy(dst_buf, src_buf, first_chunk_bytes);
memcpy(dst_buf + first_chunk_bytes, runtime->dma_area, second_chunk_bytes);
} else {
memcpy(dst_buf, src_buf, total_bytes_for_urb);
}
/* Apply routing to the contiguous data in our routing buffer */
process_playback_routing_us144mkii(tascam, dst_buf, dst_buf, frames_to_copy);
memcpy(urb->transfer_buffer, dst_buf, total_bytes_for_urb);
}
urb->dev = tascam->dev;
usb_get_urb(urb);
usb_anchor_urb(urb, &tascam->playback_anchor);
ret = usb_submit_urb(urb, GFP_ATOMIC);
if (ret < 0) {
dev_err_ratelimited(tascam->card->dev, "Failed to resubmit playback URB: %d\n", ret);
usb_unanchor_urb(urb);
usb_put_urb(urb);
}
out:
usb_put_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)
{
struct tascam_card *tascam = urb->context;
struct snd_pcm_substream *playback_ss, *capture_ss;
struct snd_pcm_runtime *playback_rt, *capture_rt;
unsigned long flags;
u64 total_frames_in_urb = 0;
int ret, p;
unsigned int old_in_idx, new_in_idx;
bool playback_period_elapsed = false;
bool capture_period_elapsed = false;
if (urb->status) {
if (urb->status != -ENOENT && urb->status != -ECONNRESET && urb->status != -ESHUTDOWN &&
urb->status != -ENODEV)
dev_err_ratelimited(tascam->card->dev, "Feedback URB failed: %d\n", urb->status);
goto out;
}
if (!tascam || !atomic_read(&tascam->playback_active))
goto out;
playback_ss = tascam->playback_substream;
if (!playback_ss || !playback_ss->runtime)
goto out;
playback_rt = playback_ss->runtime;
capture_ss = tascam->capture_substream;
capture_rt = capture_ss ? capture_ss->runtime : NULL;
spin_lock_irqsave(&tascam->lock, flags);
if (tascam->feedback_urb_skip_count > 0) {
tascam->feedback_urb_skip_count--;
goto unlock_and_continue;
}
old_in_idx = tascam->feedback_pattern_in_idx;
for (p = 0; p < urb->number_of_packets; p++) {
u8 feedback_value = 0;
const unsigned int *pattern;
bool packet_ok = (urb->iso_frame_desc[p].status == 0 &&
urb->iso_frame_desc[p].actual_length >= 1);
if (packet_ok)
feedback_value = *((u8 *)urb->transfer_buffer + urb->iso_frame_desc[p].offset);
if (packet_ok && feedback_value >= tascam->feedback_base_value &&
feedback_value <= tascam->feedback_max_value) {
pattern = tascam->feedback_patterns[feedback_value - tascam->feedback_base_value];
tascam->feedback_consecutive_errors = 0;
int i;
for (i = 0; i < 8; i++) {
unsigned int in_idx = (tascam->feedback_pattern_in_idx + i) % FEEDBACK_ACCUMULATOR_SIZE;
tascam->feedback_accumulator_pattern[in_idx] = pattern[i];
total_frames_in_urb += pattern[i];
}
} else {
unsigned int nominal_frames = playback_rt->rate / 8000;
int i;
if (tascam->feedback_synced) {
tascam->feedback_consecutive_errors++;
if (tascam->feedback_consecutive_errors > FEEDBACK_SYNC_LOSS_THRESHOLD) {
dev_err(tascam->card->dev, "Fatal: Feedback sync lost. Stopping stream.\n");
if (playback_ss)
snd_pcm_stop(playback_ss, SNDRV_PCM_STATE_XRUN);
if (capture_ss)
snd_pcm_stop(capture_ss, SNDRV_PCM_STATE_XRUN);
tascam->feedback_synced = false;
goto unlock_and_continue;
}
}
for (i = 0; i < 8; i++) {
unsigned int in_idx = (tascam->feedback_pattern_in_idx + i) % FEEDBACK_ACCUMULATOR_SIZE;
tascam->feedback_accumulator_pattern[in_idx] = nominal_frames;
total_frames_in_urb += nominal_frames;
}
}
tascam->feedback_pattern_in_idx = (tascam->feedback_pattern_in_idx + 8) % FEEDBACK_ACCUMULATOR_SIZE;
}
new_in_idx = tascam->feedback_pattern_in_idx;
if (!tascam->feedback_synced) {
unsigned int out_idx = tascam->feedback_pattern_out_idx;
bool is_ahead = (new_in_idx - out_idx) % FEEDBACK_ACCUMULATOR_SIZE < (FEEDBACK_ACCUMULATOR_SIZE / 2);
bool was_behind = (old_in_idx - out_idx) % FEEDBACK_ACCUMULATOR_SIZE >= (FEEDBACK_ACCUMULATOR_SIZE / 2);
if (is_ahead && was_behind) {
dev_dbg(tascam->card->dev, "Sync Acquired! (in: %u, out: %u)\n", new_in_idx, out_idx);
tascam->feedback_synced = true;
tascam->feedback_consecutive_errors = 0;
}
}
if (total_frames_in_urb > 0) {
tascam->playback_frames_consumed += total_frames_in_urb;
if (atomic_read(&tascam->capture_active))
tascam->capture_frames_processed += total_frames_in_urb;
}
if (playback_rt->period_size > 0) {
u64 current_period = div_u64(tascam->playback_frames_consumed, playback_rt->period_size);
if (current_period > tascam->last_period_pos) {
tascam->last_period_pos = current_period;
playback_period_elapsed = true;
}
}
if (atomic_read(&tascam->capture_active) && capture_rt && capture_rt->period_size > 0) {
u64 current_capture_period = div_u64(tascam->capture_frames_processed, capture_rt->period_size);
if (current_capture_period > tascam->last_capture_period_pos) {
tascam->last_capture_period_pos = current_capture_period;
capture_period_elapsed = true;
}
}
unlock_and_continue:
spin_unlock_irqrestore(&tascam->lock, flags);
if (playback_period_elapsed)
snd_pcm_period_elapsed(playback_ss);
if (capture_period_elapsed)
snd_pcm_period_elapsed(capture_ss);
urb->dev = tascam->dev;
usb_get_urb(urb);
usb_anchor_urb(urb, &tascam->feedback_anchor);
ret = usb_submit_urb(urb, GFP_ATOMIC);
if (ret < 0) {
dev_err_ratelimited(tascam->card->dev, "Failed to resubmit feedback URB: %d\n", ret);
usb_unanchor_urb(urb);
usb_put_urb(urb);
}
out:
usb_put_urb(urb);
}

2
us144mkii.c
View File

@ -423,7 +423,7 @@ static int tascam_resume(struct usb_interface *intf)
* @usb_id: The USB device ID.
*
* This function is the entry point for the USB driver when a matching device
* is found. It performs initial device setup, including:
* is found. It performs initial device setup, including:
* - Checking for the second interface (MIDI) and associating it.
* - Performing a vendor-specific handshake with the device.
* - Setting alternate settings for USB interfaces.

67
us144mkii.h
View File

@ -284,71 +284,8 @@ int tascam_alloc_urbs(struct tascam_card *tascam);
*/
void tascam_stop_work_handler(struct work_struct *work);
/* pcm.c */
/**
* 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 (applying routing), 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_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);
/**
* 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;
/* pcm.h */
#include "pcm.h"
/* midi.c */
/**