/* * Audio and Music Data Transmission Protocol (IEC 61883-6) streams * with Common Isochronous Packet (IEC 61883-1) headers * * Copyright (c) Clemens Ladisch <clemens@ladisch.de> * Licensed under the terms of the GNU General Public License, version 2. */ #include <linux/device.h> #include <linux/err.h> #include <linux/firewire.h> #include <linux/module.h> #include <linux/slab.h> #include <sound/pcm.h> #include <sound/pcm_params.h> #include "amdtp-stream.h" #define TICKS_PER_CYCLE 3072 #define CYCLES_PER_SECOND 8000 #define TICKS_PER_SECOND (TICKS_PER_CYCLE * CYCLES_PER_SECOND) /* Always support Linux tracing subsystem. */ #define CREATE_TRACE_POINTS #include "amdtp-stream-trace.h" #define TRANSFER_DELAY_TICKS 0x2e00 /* 479.17 microseconds */ /* isochronous header parameters */ #define ISO_DATA_LENGTH_SHIFT 16 #define TAG_CIP 1 /* common isochronous packet header parameters */ #define CIP_EOH_SHIFT 31 #define CIP_EOH (1u << CIP_EOH_SHIFT) #define CIP_EOH_MASK 0x80000000 #define CIP_SID_SHIFT 24 #define CIP_SID_MASK 0x3f000000 #define CIP_DBS_MASK 0x00ff0000 #define CIP_DBS_SHIFT 16 #define CIP_DBC_MASK 0x000000ff #define CIP_FMT_SHIFT 24 #define CIP_FMT_MASK 0x3f000000 #define CIP_FDF_MASK 0x00ff0000 #define CIP_FDF_SHIFT 16 #define CIP_SYT_MASK 0x0000ffff #define CIP_SYT_NO_INFO 0xffff /* Audio and Music transfer protocol specific parameters */ #define CIP_FMT_AM 0x10 #define AMDTP_FDF_NO_DATA 0xff /* TODO: make these configurable */ #define INTERRUPT_INTERVAL 16 #define QUEUE_LENGTH 48 #define IN_PACKET_HEADER_SIZE 4 #define OUT_PACKET_HEADER_SIZE 0 static void pcm_period_tasklet(unsigned long data); /** * amdtp_stream_init - initialize an AMDTP stream structure * @s: the AMDTP stream to initialize * @unit: the target of the stream * @dir: the direction of stream * @flags: the packet transmission method to use * @fmt: the value of fmt field in CIP header * @process_data_blocks: callback handler to process data blocks * @protocol_size: the size to allocate newly for protocol */ int amdtp_stream_init(struct amdtp_stream *s, struct fw_unit *unit, enum amdtp_stream_direction dir, enum cip_flags flags, unsigned int fmt, amdtp_stream_process_data_blocks_t process_data_blocks, unsigned int protocol_size) { if (process_data_blocks == NULL) return -EINVAL; s->protocol = kzalloc(protocol_size, GFP_KERNEL); if (!s->protocol) return -ENOMEM; s->unit = unit; s->direction = dir; s->flags = flags; s->context = ERR_PTR(-1); mutex_init(&s->mutex); tasklet_init(&s->period_tasklet, pcm_period_tasklet, (unsigned long)s); s->packet_index = 0; init_waitqueue_head(&s->callback_wait); s->callbacked = false; s->fmt = fmt; s->process_data_blocks = process_data_blocks; return 0; } EXPORT_SYMBOL(amdtp_stream_init); /** * amdtp_stream_destroy - free stream resources * @s: the AMDTP stream to destroy */ void amdtp_stream_destroy(struct amdtp_stream *s) { /* Not initialized. */ if (s->protocol == NULL) return; WARN_ON(amdtp_stream_running(s)); kfree(s->protocol); mutex_destroy(&s->mutex); } EXPORT_SYMBOL(amdtp_stream_destroy); const unsigned int amdtp_syt_intervals[CIP_SFC_COUNT] = { [CIP_SFC_32000] = 8, [CIP_SFC_44100] = 8, [CIP_SFC_48000] = 8, [CIP_SFC_88200] = 16, [CIP_SFC_96000] = 16, [CIP_SFC_176400] = 32, [CIP_SFC_192000] = 32, }; EXPORT_SYMBOL(amdtp_syt_intervals); const unsigned int amdtp_rate_table[CIP_SFC_COUNT] = { [CIP_SFC_32000] = 32000, [CIP_SFC_44100] = 44100, [CIP_SFC_48000] = 48000, [CIP_SFC_88200] = 88200, [CIP_SFC_96000] = 96000, [CIP_SFC_176400] = 176400, [CIP_SFC_192000] = 192000, }; EXPORT_SYMBOL(amdtp_rate_table); /** * amdtp_stream_add_pcm_hw_constraints - add hw constraints for PCM substream * @s: the AMDTP stream, which must be initialized. * @runtime: the PCM substream runtime */ int amdtp_stream_add_pcm_hw_constraints(struct amdtp_stream *s, struct snd_pcm_runtime *runtime) { int err; /* * Currently firewire-lib processes 16 packets in one software * interrupt callback. This equals to 2msec but actually the * interval of the interrupts has a jitter. * Additionally, even if adding a constraint to fit period size to * 2msec, actual calculated frames per period doesn't equal to 2msec, * depending on sampling rate. * Anyway, the interval to call snd_pcm_period_elapsed() cannot 2msec. * Here let us use 5msec for safe period interrupt. */ err = snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIOD_TIME, 5000, UINT_MAX); if (err < 0) goto end; /* Non-Blocking stream has no more constraints */ if (!(s->flags & CIP_BLOCKING)) goto end; /* * One AMDTP packet can include some frames. In blocking mode, the * number equals to SYT_INTERVAL. So the number is 8, 16 or 32, * depending on its sampling rate. For accurate period interrupt, it's * preferrable to align period/buffer sizes to current SYT_INTERVAL. * * TODO: These constraints can be improved with proper rules. * Currently apply LCM of SYT_INTERVALs. */ err = snd_pcm_hw_constraint_step(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, 32); if (err < 0) goto end; err = snd_pcm_hw_constraint_step(runtime, 0, SNDRV_PCM_HW_PARAM_BUFFER_SIZE, 32); end: return err; } EXPORT_SYMBOL(amdtp_stream_add_pcm_hw_constraints); /** * amdtp_stream_set_parameters - set stream parameters * @s: the AMDTP stream to configure * @rate: the sample rate * @data_block_quadlets: the size of a data block in quadlet unit * * The parameters must be set before the stream is started, and must not be * changed while the stream is running. */ int amdtp_stream_set_parameters(struct amdtp_stream *s, unsigned int rate, unsigned int data_block_quadlets) { unsigned int sfc; for (sfc = 0; sfc < ARRAY_SIZE(amdtp_rate_table); ++sfc) { if (amdtp_rate_table[sfc] == rate) break; } if (sfc == ARRAY_SIZE(amdtp_rate_table)) return -EINVAL; s->sfc = sfc; s->data_block_quadlets = data_block_quadlets; s->syt_interval = amdtp_syt_intervals[sfc]; /* default buffering in the device */ s->transfer_delay = TRANSFER_DELAY_TICKS - TICKS_PER_CYCLE; if (s->flags & CIP_BLOCKING) /* additional buffering needed to adjust for no-data packets */ s->transfer_delay += TICKS_PER_SECOND * s->syt_interval / rate; return 0; } EXPORT_SYMBOL(amdtp_stream_set_parameters); /** * amdtp_stream_get_max_payload - get the stream's packet size * @s: the AMDTP stream * * This function must not be called before the stream has been configured * with amdtp_stream_set_parameters(). */ unsigned int amdtp_stream_get_max_payload(struct amdtp_stream *s) { unsigned int multiplier = 1; if (s->flags & CIP_JUMBO_PAYLOAD) multiplier = 5; return 8 + s->syt_interval * s->data_block_quadlets * 4 * multiplier; } EXPORT_SYMBOL(amdtp_stream_get_max_payload); /** * amdtp_stream_pcm_prepare - prepare PCM device for running * @s: the AMDTP stream * * This function should be called from the PCM device's .prepare callback. */ void amdtp_stream_pcm_prepare(struct amdtp_stream *s) { tasklet_kill(&s->period_tasklet); s->pcm_buffer_pointer = 0; s->pcm_period_pointer = 0; } EXPORT_SYMBOL(amdtp_stream_pcm_prepare); static unsigned int calculate_data_blocks(struct amdtp_stream *s, unsigned int syt) { unsigned int phase, data_blocks; /* Blocking mode. */ if (s->flags & CIP_BLOCKING) { /* This module generate empty packet for 'no data'. */ if (syt == CIP_SYT_NO_INFO) data_blocks = 0; else data_blocks = s->syt_interval; /* Non-blocking mode. */ } else { if (!cip_sfc_is_base_44100(s->sfc)) { /* Sample_rate / 8000 is an integer, and precomputed. */ data_blocks = s->data_block_state; } else { phase = s->data_block_state; /* * This calculates the number of data blocks per packet so that * 1) the overall rate is correct and exactly synchronized to * the bus clock, and * 2) packets with a rounded-up number of blocks occur as early * as possible in the sequence (to prevent underruns of the * device's buffer). */ if (s->sfc == CIP_SFC_44100) /* 6 6 5 6 5 6 5 ... */ data_blocks = 5 + ((phase & 1) ^ (phase == 0 || phase >= 40)); else /* 12 11 11 11 11 ... or 23 22 22 22 22 ... */ data_blocks = 11 * (s->sfc >> 1) + (phase == 0); if (++phase >= (80 >> (s->sfc >> 1))) phase = 0; s->data_block_state = phase; } } return data_blocks; } static unsigned int calculate_syt(struct amdtp_stream *s, unsigned int cycle) { unsigned int syt_offset, phase, index, syt; if (s->last_syt_offset < TICKS_PER_CYCLE) { if (!cip_sfc_is_base_44100(s->sfc)) syt_offset = s->last_syt_offset + s->syt_offset_state; else { /* * The time, in ticks, of the n'th SYT_INTERVAL sample is: * n * SYT_INTERVAL * 24576000 / sample_rate * Modulo TICKS_PER_CYCLE, the difference between successive * elements is about 1386.23. Rounding the results of this * formula to the SYT precision results in a sequence of * differences that begins with: * 1386 1386 1387 1386 1386 1386 1387 1386 1386 1386 1387 ... * This code generates _exactly_ the same sequence. */ phase = s->syt_offset_state; index = phase % 13; syt_offset = s->last_syt_offset; syt_offset += 1386 + ((index && !(index & 3)) || phase == 146); if (++phase >= 147) phase = 0; s->syt_offset_state = phase; } } else syt_offset = s->last_syt_offset - TICKS_PER_CYCLE; s->last_syt_offset = syt_offset; if (syt_offset < TICKS_PER_CYCLE) { syt_offset += s->transfer_delay; syt = (cycle + syt_offset / TICKS_PER_CYCLE) << 12; syt += syt_offset % TICKS_PER_CYCLE; return syt & CIP_SYT_MASK; } else { return CIP_SYT_NO_INFO; } } static void update_pcm_pointers(struct amdtp_stream *s, struct snd_pcm_substream *pcm, unsigned int frames) { unsigned int ptr; ptr = s->pcm_buffer_pointer + frames; if (ptr >= pcm->runtime->buffer_size) ptr -= pcm->runtime->buffer_size; ACCESS_ONCE(s->pcm_buffer_pointer) = ptr; s->pcm_period_pointer += frames; if (s->pcm_period_pointer >= pcm->runtime->period_size) { s->pcm_period_pointer -= pcm->runtime->period_size; tasklet_hi_schedule(&s->period_tasklet); } } static void pcm_period_tasklet(unsigned long data) { struct amdtp_stream *s = (void *)data; struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm); if (pcm) snd_pcm_period_elapsed(pcm); } static int queue_packet(struct amdtp_stream *s, unsigned int header_length, unsigned int payload_length) { struct fw_iso_packet p = {0}; int err = 0; if (IS_ERR(s->context)) goto end; p.interrupt = IS_ALIGNED(s->packet_index + 1, INTERRUPT_INTERVAL); p.tag = TAG_CIP; p.header_length = header_length; if (payload_length > 0) p.payload_length = payload_length; else p.skip = true; err = fw_iso_context_queue(s->context, &p, &s->buffer.iso_buffer, s->buffer.packets[s->packet_index].offset); if (err < 0) { dev_err(&s->unit->device, "queueing error: %d\n", err); goto end; } if (++s->packet_index >= QUEUE_LENGTH) s->packet_index = 0; end: return err; } static inline int queue_out_packet(struct amdtp_stream *s, unsigned int payload_length) { return queue_packet(s, OUT_PACKET_HEADER_SIZE, payload_length); } static inline int queue_in_packet(struct amdtp_stream *s) { return queue_packet(s, IN_PACKET_HEADER_SIZE, amdtp_stream_get_max_payload(s)); } static int handle_out_packet(struct amdtp_stream *s, unsigned int cycle, unsigned int index) { __be32 *buffer; unsigned int syt; unsigned int data_blocks; unsigned int payload_length; unsigned int pcm_frames; struct snd_pcm_substream *pcm; buffer = s->buffer.packets[s->packet_index].buffer; syt = calculate_syt(s, cycle); data_blocks = calculate_data_blocks(s, syt); pcm_frames = s->process_data_blocks(s, buffer + 2, data_blocks, &syt); buffer[0] = cpu_to_be32(ACCESS_ONCE(s->source_node_id_field) | (s->data_block_quadlets << CIP_DBS_SHIFT) | s->data_block_counter); buffer[1] = cpu_to_be32(CIP_EOH | ((s->fmt << CIP_FMT_SHIFT) & CIP_FMT_MASK) | ((s->fdf << CIP_FDF_SHIFT) & CIP_FDF_MASK) | (syt & CIP_SYT_MASK)); s->data_block_counter = (s->data_block_counter + data_blocks) & 0xff; payload_length = 8 + data_blocks * 4 * s->data_block_quadlets; trace_out_packet(s, cycle, buffer, payload_length, index); if (queue_out_packet(s, payload_length) < 0) return -EIO; pcm = ACCESS_ONCE(s->pcm); if (pcm && pcm_frames > 0) update_pcm_pointers(s, pcm, pcm_frames); /* No need to return the number of handled data blocks. */ return 0; } static int handle_in_packet(struct amdtp_stream *s, unsigned int payload_quadlets, unsigned int cycle, unsigned int index) { __be32 *buffer; u32 cip_header[2]; unsigned int fmt, fdf, syt; unsigned int data_block_quadlets, data_block_counter, dbc_interval; unsigned int data_blocks; struct snd_pcm_substream *pcm; unsigned int pcm_frames; bool lost; buffer = s->buffer.packets[s->packet_index].buffer; cip_header[0] = be32_to_cpu(buffer[0]); cip_header[1] = be32_to_cpu(buffer[1]); trace_in_packet(s, cycle, cip_header, payload_quadlets, index); /* * This module supports 'Two-quadlet CIP header with SYT field'. * For convenience, also check FMT field is AM824 or not. */ if (((cip_header[0] & CIP_EOH_MASK) == CIP_EOH) || ((cip_header[1] & CIP_EOH_MASK) != CIP_EOH)) { dev_info_ratelimited(&s->unit->device, "Invalid CIP header for AMDTP: %08X:%08X\n", cip_header[0], cip_header[1]); data_blocks = 0; pcm_frames = 0; goto end; } /* Check valid protocol or not. */ fmt = (cip_header[1] & CIP_FMT_MASK) >> CIP_FMT_SHIFT; if (fmt != s->fmt) { dev_info_ratelimited(&s->unit->device, "Detect unexpected protocol: %08x %08x\n", cip_header[0], cip_header[1]); data_blocks = 0; pcm_frames = 0; goto end; } /* Calculate data blocks */ fdf = (cip_header[1] & CIP_FDF_MASK) >> CIP_FDF_SHIFT; if (payload_quadlets < 3 || (fmt == CIP_FMT_AM && fdf == AMDTP_FDF_NO_DATA)) { data_blocks = 0; } else { data_block_quadlets = (cip_header[0] & CIP_DBS_MASK) >> CIP_DBS_SHIFT; /* avoid division by zero */ if (data_block_quadlets == 0) { dev_err(&s->unit->device, "Detect invalid value in dbs field: %08X\n", cip_header[0]); return -EPROTO; } if (s->flags & CIP_WRONG_DBS) data_block_quadlets = s->data_block_quadlets; data_blocks = (payload_quadlets - 2) / data_block_quadlets; } /* Check data block counter continuity */ data_block_counter = cip_header[0] & CIP_DBC_MASK; if (data_blocks == 0 && (s->flags & CIP_EMPTY_HAS_WRONG_DBC) && s->data_block_counter != UINT_MAX) data_block_counter = s->data_block_counter; if (((s->flags & CIP_SKIP_DBC_ZERO_CHECK) && data_block_counter == s->tx_first_dbc) || s->data_block_counter == UINT_MAX) { lost = false; } else if (!(s->flags & CIP_DBC_IS_END_EVENT)) { lost = data_block_counter != s->data_block_counter; } else { if (data_blocks > 0 && s->tx_dbc_interval > 0) dbc_interval = s->tx_dbc_interval; else dbc_interval = data_blocks; lost = data_block_counter != ((s->data_block_counter + dbc_interval) & 0xff); } if (lost) { dev_err(&s->unit->device, "Detect discontinuity of CIP: %02X %02X\n", s->data_block_counter, data_block_counter); return -EIO; } syt = be32_to_cpu(buffer[1]) & CIP_SYT_MASK; pcm_frames = s->process_data_blocks(s, buffer + 2, data_blocks, &syt); if (s->flags & CIP_DBC_IS_END_EVENT) s->data_block_counter = data_block_counter; else s->data_block_counter = (data_block_counter + data_blocks) & 0xff; end: if (queue_in_packet(s) < 0) return -EIO; pcm = ACCESS_ONCE(s->pcm); if (pcm && pcm_frames > 0) update_pcm_pointers(s, pcm, pcm_frames); return 0; } /* * In CYCLE_TIMER register of IEEE 1394, 7 bits are used to represent second. On * the other hand, in DMA descriptors of 1394 OHCI, 3 bits are used to represent * it. Thus, via Linux firewire subsystem, we can get the 3 bits for second. */ static inline u32 compute_cycle_count(u32 tstamp) { return (((tstamp >> 13) & 0x07) * 8000) + (tstamp & 0x1fff); } static inline u32 increment_cycle_count(u32 cycle, unsigned int addend) { cycle += addend; if (cycle >= 8 * CYCLES_PER_SECOND) cycle -= 8 * CYCLES_PER_SECOND; return cycle; } static inline u32 decrement_cycle_count(u32 cycle, unsigned int subtrahend) { if (cycle < subtrahend) cycle += 8 * CYCLES_PER_SECOND; return cycle - subtrahend; } static void out_stream_callback(struct fw_iso_context *context, u32 tstamp, size_t header_length, void *header, void *private_data) { struct amdtp_stream *s = private_data; unsigned int i, packets = header_length / 4; u32 cycle; if (s->packet_index < 0) return; cycle = compute_cycle_count(tstamp); /* Align to actual cycle count for the last packet. */ cycle = increment_cycle_count(cycle, QUEUE_LENGTH - packets); for (i = 0; i < packets; ++i) { cycle = increment_cycle_count(cycle, 1); if (handle_out_packet(s, cycle, i) < 0) { s->packet_index = -1; amdtp_stream_pcm_abort(s); return; } } fw_iso_context_queue_flush(s->context); } static void in_stream_callback(struct fw_iso_context *context, u32 tstamp, size_t header_length, void *header, void *private_data) { struct amdtp_stream *s = private_data; unsigned int i, packets; unsigned int payload_quadlets, max_payload_quadlets; __be32 *headers = header; u32 cycle; if (s->packet_index < 0) return; /* The number of packets in buffer */ packets = header_length / IN_PACKET_HEADER_SIZE; cycle = compute_cycle_count(tstamp); /* Align to actual cycle count for the last packet. */ cycle = decrement_cycle_count(cycle, packets); /* For buffer-over-run prevention. */ max_payload_quadlets = amdtp_stream_get_max_payload(s) / 4; for (i = 0; i < packets; i++) { cycle = increment_cycle_count(cycle, 1); /* The number of quadlets in this packet */ payload_quadlets = (be32_to_cpu(headers[i]) >> ISO_DATA_LENGTH_SHIFT) / 4; if (payload_quadlets > max_payload_quadlets) { dev_err(&s->unit->device, "Detect jumbo payload: %02x %02x\n", payload_quadlets, max_payload_quadlets); break; } if (handle_in_packet(s, payload_quadlets, cycle, i) < 0) break; } /* Queueing error or detecting invalid payload. */ if (i < packets) { s->packet_index = -1; amdtp_stream_pcm_abort(s); return; } fw_iso_context_queue_flush(s->context); } /* this is executed one time */ static void amdtp_stream_first_callback(struct fw_iso_context *context, u32 tstamp, size_t header_length, void *header, void *private_data) { struct amdtp_stream *s = private_data; /* * For in-stream, first packet has come. * For out-stream, prepared to transmit first packet */ s->callbacked = true; wake_up(&s->callback_wait); if (s->direction == AMDTP_IN_STREAM) context->callback.sc = in_stream_callback; else context->callback.sc = out_stream_callback; context->callback.sc(context, tstamp, header_length, header, s); } /** * amdtp_stream_start - start transferring packets * @s: the AMDTP stream to start * @channel: the isochronous channel on the bus * @speed: firewire speed code * * The stream cannot be started until it has been configured with * amdtp_stream_set_parameters() and it must be started before any PCM or MIDI * device can be started. */ int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed) { static const struct { unsigned int data_block; unsigned int syt_offset; } initial_state[] = { [CIP_SFC_32000] = { 4, 3072 }, [CIP_SFC_48000] = { 6, 1024 }, [CIP_SFC_96000] = { 12, 1024 }, [CIP_SFC_192000] = { 24, 1024 }, [CIP_SFC_44100] = { 0, 67 }, [CIP_SFC_88200] = { 0, 67 }, [CIP_SFC_176400] = { 0, 67 }, }; unsigned int header_size; enum dma_data_direction dir; int type, tag, err; mutex_lock(&s->mutex); if (WARN_ON(amdtp_stream_running(s) || (s->data_block_quadlets < 1))) { err = -EBADFD; goto err_unlock; } if (s->direction == AMDTP_IN_STREAM) s->data_block_counter = UINT_MAX; else s->data_block_counter = 0; s->data_block_state = initial_state[s->sfc].data_block; s->syt_offset_state = initial_state[s->sfc].syt_offset; s->last_syt_offset = TICKS_PER_CYCLE; /* initialize packet buffer */ if (s->direction == AMDTP_IN_STREAM) { dir = DMA_FROM_DEVICE; type = FW_ISO_CONTEXT_RECEIVE; header_size = IN_PACKET_HEADER_SIZE; } else { dir = DMA_TO_DEVICE; type = FW_ISO_CONTEXT_TRANSMIT; header_size = OUT_PACKET_HEADER_SIZE; } err = iso_packets_buffer_init(&s->buffer, s->unit, QUEUE_LENGTH, amdtp_stream_get_max_payload(s), dir); if (err < 0) goto err_unlock; s->context = fw_iso_context_create(fw_parent_device(s->unit)->card, type, channel, speed, header_size, amdtp_stream_first_callback, s); if (IS_ERR(s->context)) { err = PTR_ERR(s->context); if (err == -EBUSY) dev_err(&s->unit->device, "no free stream on this controller\n"); goto err_buffer; } amdtp_stream_update(s); s->packet_index = 0; do { if (s->direction == AMDTP_IN_STREAM) err = queue_in_packet(s); else err = queue_out_packet(s, 0); if (err < 0) goto err_context; } while (s->packet_index > 0); /* NOTE: TAG1 matches CIP. This just affects in stream. */ tag = FW_ISO_CONTEXT_MATCH_TAG1; if (s->flags & CIP_EMPTY_WITH_TAG0) tag |= FW_ISO_CONTEXT_MATCH_TAG0; s->callbacked = false; err = fw_iso_context_start(s->context, -1, 0, tag); if (err < 0) goto err_context; mutex_unlock(&s->mutex); return 0; err_context: fw_iso_context_destroy(s->context); s->context = ERR_PTR(-1); err_buffer: iso_packets_buffer_destroy(&s->buffer, s->unit); err_unlock: mutex_unlock(&s->mutex); return err; } EXPORT_SYMBOL(amdtp_stream_start); /** * amdtp_stream_pcm_pointer - get the PCM buffer position * @s: the AMDTP stream that transports the PCM data * * Returns the current buffer position, in frames. */ unsigned long amdtp_stream_pcm_pointer(struct amdtp_stream *s) { /* * This function is called in software IRQ context of period_tasklet or * process context. * * When the software IRQ context was scheduled by software IRQ context * of IR/IT contexts, queued packets were already handled. Therefore, * no need to flush the queue in buffer anymore. * * When the process context reach here, some packets will be already * queued in the buffer. These packets should be handled immediately * to keep better granularity of PCM pointer. * * Later, the process context will sometimes schedules software IRQ * context of the period_tasklet. Then, no need to flush the queue by * the same reason as described for IR/IT contexts. */ if (!in_interrupt() && amdtp_stream_running(s)) fw_iso_context_flush_completions(s->context); return ACCESS_ONCE(s->pcm_buffer_pointer); } EXPORT_SYMBOL(amdtp_stream_pcm_pointer); /** * amdtp_stream_update - update the stream after a bus reset * @s: the AMDTP stream */ void amdtp_stream_update(struct amdtp_stream *s) { /* Precomputing. */ ACCESS_ONCE(s->source_node_id_field) = (fw_parent_device(s->unit)->card->node_id << CIP_SID_SHIFT) & CIP_SID_MASK; } EXPORT_SYMBOL(amdtp_stream_update); /** * amdtp_stream_stop - stop sending packets * @s: the AMDTP stream to stop * * All PCM and MIDI devices of the stream must be stopped before the stream * itself can be stopped. */ void amdtp_stream_stop(struct amdtp_stream *s) { mutex_lock(&s->mutex); if (!amdtp_stream_running(s)) { mutex_unlock(&s->mutex); return; } tasklet_kill(&s->period_tasklet); fw_iso_context_stop(s->context); fw_iso_context_destroy(s->context); s->context = ERR_PTR(-1); iso_packets_buffer_destroy(&s->buffer, s->unit); s->callbacked = false; mutex_unlock(&s->mutex); } EXPORT_SYMBOL(amdtp_stream_stop); /** * amdtp_stream_pcm_abort - abort the running PCM device * @s: the AMDTP stream about to be stopped * * If the isochronous stream needs to be stopped asynchronously, call this * function first to stop the PCM device. */ void amdtp_stream_pcm_abort(struct amdtp_stream *s) { struct snd_pcm_substream *pcm; pcm = ACCESS_ONCE(s->pcm); if (pcm) snd_pcm_stop_xrun(pcm); } EXPORT_SYMBOL(amdtp_stream_pcm_abort);