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428 lines
12 KiB
428 lines
12 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* AM824 format in Audio and Music Data Transmission Protocol (IEC 61883-6) |
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* |
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* Copyright (c) Clemens Ladisch <[email protected]> |
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* Copyright (c) 2015 Takashi Sakamoto <[email protected]> |
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*/ |
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#include <linux/slab.h> |
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#include "amdtp-am824.h" |
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#define CIP_FMT_AM 0x10 |
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/* "Clock-based rate control mode" is just supported. */ |
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#define AMDTP_FDF_AM824 0x00 |
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/* |
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* Nominally 3125 bytes/second, but the MIDI port's clock might be |
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* 1% too slow, and the bus clock 100 ppm too fast. |
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*/ |
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#define MIDI_BYTES_PER_SECOND 3093 |
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/* |
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* Several devices look only at the first eight data blocks. |
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* In any case, this is more than enough for the MIDI data rate. |
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*/ |
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#define MAX_MIDI_RX_BLOCKS 8 |
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struct amdtp_am824 { |
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struct snd_rawmidi_substream *midi[AM824_MAX_CHANNELS_FOR_MIDI * 8]; |
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int midi_fifo_limit; |
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int midi_fifo_used[AM824_MAX_CHANNELS_FOR_MIDI * 8]; |
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unsigned int pcm_channels; |
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unsigned int midi_ports; |
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u8 pcm_positions[AM824_MAX_CHANNELS_FOR_PCM]; |
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u8 midi_position; |
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unsigned int frame_multiplier; |
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}; |
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/** |
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* amdtp_am824_set_parameters - set stream parameters |
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* @s: the AMDTP stream to configure |
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* @rate: the sample rate |
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* @pcm_channels: the number of PCM samples in each data block, to be encoded |
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* as AM824 multi-bit linear audio |
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* @midi_ports: the number of MIDI ports (i.e., MPX-MIDI Data Channels) |
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* @double_pcm_frames: one data block transfers two PCM frames |
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* |
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* The parameters must be set before the stream is started, and must not be |
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* changed while the stream is running. |
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*/ |
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int amdtp_am824_set_parameters(struct amdtp_stream *s, unsigned int rate, |
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unsigned int pcm_channels, |
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unsigned int midi_ports, |
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bool double_pcm_frames) |
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{ |
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struct amdtp_am824 *p = s->protocol; |
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unsigned int midi_channels; |
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unsigned int i; |
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int err; |
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if (amdtp_stream_running(s)) |
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return -EINVAL; |
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if (pcm_channels > AM824_MAX_CHANNELS_FOR_PCM) |
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return -EINVAL; |
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midi_channels = DIV_ROUND_UP(midi_ports, 8); |
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if (midi_channels > AM824_MAX_CHANNELS_FOR_MIDI) |
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return -EINVAL; |
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if (WARN_ON(amdtp_stream_running(s)) || |
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WARN_ON(pcm_channels > AM824_MAX_CHANNELS_FOR_PCM) || |
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WARN_ON(midi_channels > AM824_MAX_CHANNELS_FOR_MIDI)) |
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return -EINVAL; |
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err = amdtp_stream_set_parameters(s, rate, |
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pcm_channels + midi_channels); |
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if (err < 0) |
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return err; |
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if (s->direction == AMDTP_OUT_STREAM) |
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s->ctx_data.rx.fdf = AMDTP_FDF_AM824 | s->sfc; |
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p->pcm_channels = pcm_channels; |
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p->midi_ports = midi_ports; |
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/* |
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* In IEC 61883-6, one data block represents one event. In ALSA, one |
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* event equals to one PCM frame. But Dice has a quirk at higher |
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* sampling rate to transfer two PCM frames in one data block. |
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*/ |
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if (double_pcm_frames) |
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p->frame_multiplier = 2; |
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else |
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p->frame_multiplier = 1; |
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/* init the position map for PCM and MIDI channels */ |
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for (i = 0; i < pcm_channels; i++) |
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p->pcm_positions[i] = i; |
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p->midi_position = p->pcm_channels; |
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/* |
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* We do not know the actual MIDI FIFO size of most devices. Just |
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* assume two bytes, i.e., one byte can be received over the bus while |
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* the previous one is transmitted over MIDI. |
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* (The value here is adjusted for midi_ratelimit_per_packet().) |
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*/ |
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p->midi_fifo_limit = rate - MIDI_BYTES_PER_SECOND * s->syt_interval + 1; |
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return 0; |
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} |
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EXPORT_SYMBOL_GPL(amdtp_am824_set_parameters); |
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/** |
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* amdtp_am824_set_pcm_position - set an index of data channel for a channel |
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* of PCM frame |
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* @s: the AMDTP stream |
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* @index: the index of data channel in an data block |
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* @position: the channel of PCM frame |
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*/ |
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void amdtp_am824_set_pcm_position(struct amdtp_stream *s, unsigned int index, |
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unsigned int position) |
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{ |
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struct amdtp_am824 *p = s->protocol; |
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if (index < p->pcm_channels) |
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p->pcm_positions[index] = position; |
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} |
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EXPORT_SYMBOL_GPL(amdtp_am824_set_pcm_position); |
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/** |
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* amdtp_am824_set_midi_position - set a index of data channel for MIDI |
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* conformant data channel |
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* @s: the AMDTP stream |
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* @position: the index of data channel in an data block |
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*/ |
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void amdtp_am824_set_midi_position(struct amdtp_stream *s, |
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unsigned int position) |
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{ |
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struct amdtp_am824 *p = s->protocol; |
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p->midi_position = position; |
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} |
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EXPORT_SYMBOL_GPL(amdtp_am824_set_midi_position); |
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static void write_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm, |
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__be32 *buffer, unsigned int frames, |
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unsigned int pcm_frames) |
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{ |
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struct amdtp_am824 *p = s->protocol; |
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unsigned int channels = p->pcm_channels; |
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struct snd_pcm_runtime *runtime = pcm->runtime; |
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unsigned int pcm_buffer_pointer; |
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int remaining_frames; |
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const u32 *src; |
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int i, c; |
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pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames; |
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pcm_buffer_pointer %= runtime->buffer_size; |
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src = (void *)runtime->dma_area + |
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frames_to_bytes(runtime, pcm_buffer_pointer); |
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remaining_frames = runtime->buffer_size - pcm_buffer_pointer; |
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for (i = 0; i < frames; ++i) { |
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for (c = 0; c < channels; ++c) { |
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buffer[p->pcm_positions[c]] = |
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cpu_to_be32((*src >> 8) | 0x40000000); |
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src++; |
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} |
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buffer += s->data_block_quadlets; |
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if (--remaining_frames == 0) |
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src = (void *)runtime->dma_area; |
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} |
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} |
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static void read_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm, |
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__be32 *buffer, unsigned int frames, |
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unsigned int pcm_frames) |
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{ |
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struct amdtp_am824 *p = s->protocol; |
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unsigned int channels = p->pcm_channels; |
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struct snd_pcm_runtime *runtime = pcm->runtime; |
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unsigned int pcm_buffer_pointer; |
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int remaining_frames; |
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u32 *dst; |
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int i, c; |
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pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames; |
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pcm_buffer_pointer %= runtime->buffer_size; |
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dst = (void *)runtime->dma_area + |
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frames_to_bytes(runtime, pcm_buffer_pointer); |
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remaining_frames = runtime->buffer_size - pcm_buffer_pointer; |
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for (i = 0; i < frames; ++i) { |
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for (c = 0; c < channels; ++c) { |
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*dst = be32_to_cpu(buffer[p->pcm_positions[c]]) << 8; |
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dst++; |
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} |
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buffer += s->data_block_quadlets; |
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if (--remaining_frames == 0) |
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dst = (void *)runtime->dma_area; |
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} |
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} |
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static void write_pcm_silence(struct amdtp_stream *s, |
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__be32 *buffer, unsigned int frames) |
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{ |
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struct amdtp_am824 *p = s->protocol; |
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unsigned int i, c, channels = p->pcm_channels; |
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for (i = 0; i < frames; ++i) { |
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for (c = 0; c < channels; ++c) |
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buffer[p->pcm_positions[c]] = cpu_to_be32(0x40000000); |
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buffer += s->data_block_quadlets; |
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} |
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} |
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/** |
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* amdtp_am824_add_pcm_hw_constraints - add hw constraints for PCM substream |
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* @s: the AMDTP stream for AM824 data block, must be initialized. |
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* @runtime: the PCM substream runtime |
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* |
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*/ |
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int amdtp_am824_add_pcm_hw_constraints(struct amdtp_stream *s, |
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struct snd_pcm_runtime *runtime) |
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{ |
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int err; |
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err = amdtp_stream_add_pcm_hw_constraints(s, runtime); |
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if (err < 0) |
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return err; |
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/* AM824 in IEC 61883-6 can deliver 24bit data. */ |
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return snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24); |
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} |
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EXPORT_SYMBOL_GPL(amdtp_am824_add_pcm_hw_constraints); |
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/** |
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* amdtp_am824_midi_trigger - start/stop playback/capture with a MIDI device |
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* @s: the AMDTP stream |
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* @port: index of MIDI port |
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* @midi: the MIDI device to be started, or %NULL to stop the current device |
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* |
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* Call this function on a running isochronous stream to enable the actual |
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* transmission of MIDI data. This function should be called from the MIDI |
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* device's .trigger callback. |
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*/ |
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void amdtp_am824_midi_trigger(struct amdtp_stream *s, unsigned int port, |
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struct snd_rawmidi_substream *midi) |
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{ |
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struct amdtp_am824 *p = s->protocol; |
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if (port < p->midi_ports) |
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WRITE_ONCE(p->midi[port], midi); |
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} |
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EXPORT_SYMBOL_GPL(amdtp_am824_midi_trigger); |
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/* |
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* To avoid sending MIDI bytes at too high a rate, assume that the receiving |
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* device has a FIFO, and track how much it is filled. This values increases |
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* by one whenever we send one byte in a packet, but the FIFO empties at |
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* a constant rate independent of our packet rate. One packet has syt_interval |
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* samples, so the number of bytes that empty out of the FIFO, per packet(!), |
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* is MIDI_BYTES_PER_SECOND * syt_interval / sample_rate. To avoid storing |
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* fractional values, the values in midi_fifo_used[] are measured in bytes |
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* multiplied by the sample rate. |
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*/ |
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static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port) |
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{ |
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struct amdtp_am824 *p = s->protocol; |
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int used; |
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used = p->midi_fifo_used[port]; |
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if (used == 0) /* common shortcut */ |
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return true; |
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used -= MIDI_BYTES_PER_SECOND * s->syt_interval; |
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used = max(used, 0); |
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p->midi_fifo_used[port] = used; |
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return used < p->midi_fifo_limit; |
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} |
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static void midi_rate_use_one_byte(struct amdtp_stream *s, unsigned int port) |
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{ |
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struct amdtp_am824 *p = s->protocol; |
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p->midi_fifo_used[port] += amdtp_rate_table[s->sfc]; |
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} |
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static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer, |
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unsigned int frames, unsigned int data_block_counter) |
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{ |
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struct amdtp_am824 *p = s->protocol; |
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unsigned int f, port; |
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u8 *b; |
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for (f = 0; f < frames; f++) { |
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b = (u8 *)&buffer[p->midi_position]; |
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port = (data_block_counter + f) % 8; |
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if (f < MAX_MIDI_RX_BLOCKS && |
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midi_ratelimit_per_packet(s, port) && |
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p->midi[port] != NULL && |
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snd_rawmidi_transmit(p->midi[port], &b[1], 1) == 1) { |
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midi_rate_use_one_byte(s, port); |
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b[0] = 0x81; |
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} else { |
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b[0] = 0x80; |
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b[1] = 0; |
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} |
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b[2] = 0; |
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b[3] = 0; |
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buffer += s->data_block_quadlets; |
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} |
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} |
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static void read_midi_messages(struct amdtp_stream *s, __be32 *buffer, |
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unsigned int frames, unsigned int data_block_counter) |
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{ |
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struct amdtp_am824 *p = s->protocol; |
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int len; |
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u8 *b; |
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int f; |
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for (f = 0; f < frames; f++) { |
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unsigned int port = f; |
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if (!(s->flags & CIP_UNALIGHED_DBC)) |
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port += data_block_counter; |
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port %= 8; |
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b = (u8 *)&buffer[p->midi_position]; |
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len = b[0] - 0x80; |
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if ((1 <= len) && (len <= 3) && (p->midi[port])) |
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snd_rawmidi_receive(p->midi[port], b + 1, len); |
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buffer += s->data_block_quadlets; |
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} |
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} |
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static unsigned int process_it_ctx_payloads(struct amdtp_stream *s, |
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const struct pkt_desc *descs, |
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unsigned int packets, |
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struct snd_pcm_substream *pcm) |
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{ |
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struct amdtp_am824 *p = s->protocol; |
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unsigned int pcm_frames = 0; |
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int i; |
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for (i = 0; i < packets; ++i) { |
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const struct pkt_desc *desc = descs + i; |
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__be32 *buf = desc->ctx_payload; |
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unsigned int data_blocks = desc->data_blocks; |
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if (pcm) { |
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write_pcm_s32(s, pcm, buf, data_blocks, pcm_frames); |
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pcm_frames += data_blocks * p->frame_multiplier; |
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} else { |
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write_pcm_silence(s, buf, data_blocks); |
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} |
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if (p->midi_ports) { |
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write_midi_messages(s, buf, data_blocks, |
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desc->data_block_counter); |
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} |
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} |
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return pcm_frames; |
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} |
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static unsigned int process_ir_ctx_payloads(struct amdtp_stream *s, |
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const struct pkt_desc *descs, |
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unsigned int packets, |
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struct snd_pcm_substream *pcm) |
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{ |
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struct amdtp_am824 *p = s->protocol; |
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unsigned int pcm_frames = 0; |
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int i; |
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for (i = 0; i < packets; ++i) { |
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const struct pkt_desc *desc = descs + i; |
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__be32 *buf = desc->ctx_payload; |
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unsigned int data_blocks = desc->data_blocks; |
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if (pcm) { |
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read_pcm_s32(s, pcm, buf, data_blocks, pcm_frames); |
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pcm_frames += data_blocks * p->frame_multiplier; |
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} |
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if (p->midi_ports) { |
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read_midi_messages(s, buf, data_blocks, |
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desc->data_block_counter); |
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} |
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} |
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return pcm_frames; |
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} |
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/** |
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* amdtp_am824_init - initialize an AMDTP stream structure to handle AM824 |
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* data block |
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* @s: the AMDTP stream to initialize |
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* @unit: the target of the stream |
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* @dir: the direction of stream |
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* @flags: the packet transmission method to use |
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*/ |
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int amdtp_am824_init(struct amdtp_stream *s, struct fw_unit *unit, |
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enum amdtp_stream_direction dir, enum cip_flags flags) |
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{ |
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amdtp_stream_process_ctx_payloads_t process_ctx_payloads; |
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if (dir == AMDTP_IN_STREAM) |
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process_ctx_payloads = process_ir_ctx_payloads; |
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else |
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process_ctx_payloads = process_it_ctx_payloads; |
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return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM, |
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process_ctx_payloads, sizeof(struct amdtp_am824)); |
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} |
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EXPORT_SYMBOL_GPL(amdtp_am824_init);
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