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1/*
2 * AM824 format in Audio and Music Data Transmission Protocol (IEC 61883-6)
3 *
4 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
5 * Copyright (c) 2015 Takashi Sakamoto <o-takashi@sakamocchi.jp>
6 *
7 * Licensed under the terms of the GNU General Public License, version 2.
8 */
9
10#include <linux/slab.h>
11
12#include "amdtp-am824.h"
13
14#define CIP_FMT_AM 0x10
15
16/* "Clock-based rate control mode" is just supported. */
17#define AMDTP_FDF_AM824 0x00
18
19/*
20 * Nominally 3125 bytes/second, but the MIDI port's clock might be
21 * 1% too slow, and the bus clock 100 ppm too fast.
22 */
23#define MIDI_BYTES_PER_SECOND 3093
24
25/*
26 * Several devices look only at the first eight data blocks.
27 * In any case, this is more than enough for the MIDI data rate.
28 */
29#define MAX_MIDI_RX_BLOCKS 8
30
31struct amdtp_am824 {
32 struct snd_rawmidi_substream *midi[AM824_MAX_CHANNELS_FOR_MIDI * 8];
33 int midi_fifo_limit;
34 int midi_fifo_used[AM824_MAX_CHANNELS_FOR_MIDI * 8];
35 unsigned int pcm_channels;
36 unsigned int midi_ports;
37
38 u8 pcm_positions[AM824_MAX_CHANNELS_FOR_PCM];
39 u8 midi_position;
40
41 void (*transfer_samples)(struct amdtp_stream *s,
42 struct snd_pcm_substream *pcm,
43 __be32 *buffer, unsigned int frames);
44
45 unsigned int frame_multiplier;
46};
47
48/**
49 * amdtp_am824_set_parameters - set stream parameters
50 * @s: the AMDTP stream to configure
51 * @rate: the sample rate
52 * @pcm_channels: the number of PCM samples in each data block, to be encoded
53 * as AM824 multi-bit linear audio
54 * @midi_ports: the number of MIDI ports (i.e., MPX-MIDI Data Channels)
55 * @double_pcm_frames: one data block transfers two PCM frames
56 *
57 * The parameters must be set before the stream is started, and must not be
58 * changed while the stream is running.
59 */
60int amdtp_am824_set_parameters(struct amdtp_stream *s, unsigned int rate,
61 unsigned int pcm_channels,
62 unsigned int midi_ports,
63 bool double_pcm_frames)
64{
65 struct amdtp_am824 *p = s->protocol;
66 unsigned int midi_channels;
67 unsigned int i;
68 int err;
69
70 if (amdtp_stream_running(s))
71 return -EINVAL;
72
73 if (pcm_channels > AM824_MAX_CHANNELS_FOR_PCM)
74 return -EINVAL;
75
76 midi_channels = DIV_ROUND_UP(midi_ports, 8);
77 if (midi_channels > AM824_MAX_CHANNELS_FOR_MIDI)
78 return -EINVAL;
79
80 if (WARN_ON(amdtp_stream_running(s)) ||
81 WARN_ON(pcm_channels > AM824_MAX_CHANNELS_FOR_PCM) ||
82 WARN_ON(midi_channels > AM824_MAX_CHANNELS_FOR_MIDI))
83 return -EINVAL;
84
85 err = amdtp_stream_set_parameters(s, rate,
86 pcm_channels + midi_channels);
87 if (err < 0)
88 return err;
89
90 s->fdf = AMDTP_FDF_AM824 | s->sfc;
91
92 p->pcm_channels = pcm_channels;
93 p->midi_ports = midi_ports;
94
95 /*
96 * In IEC 61883-6, one data block represents one event. In ALSA, one
97 * event equals to one PCM frame. But Dice has a quirk at higher
98 * sampling rate to transfer two PCM frames in one data block.
99 */
100 if (double_pcm_frames)
101 p->frame_multiplier = 2;
102 else
103 p->frame_multiplier = 1;
104
105 /* init the position map for PCM and MIDI channels */
106 for (i = 0; i < pcm_channels; i++)
107 p->pcm_positions[i] = i;
108 p->midi_position = p->pcm_channels;
109
110 /*
111 * We do not know the actual MIDI FIFO size of most devices. Just
112 * assume two bytes, i.e., one byte can be received over the bus while
113 * the previous one is transmitted over MIDI.
114 * (The value here is adjusted for midi_ratelimit_per_packet().)
115 */
116 p->midi_fifo_limit = rate - MIDI_BYTES_PER_SECOND * s->syt_interval + 1;
117
118 return 0;
119}
120EXPORT_SYMBOL_GPL(amdtp_am824_set_parameters);
121
122/**
123 * amdtp_am824_set_pcm_position - set an index of data channel for a channel
124 * of PCM frame
125 * @s: the AMDTP stream
126 * @index: the index of data channel in an data block
127 * @position: the channel of PCM frame
128 */
129void amdtp_am824_set_pcm_position(struct amdtp_stream *s, unsigned int index,
130 unsigned int position)
131{
132 struct amdtp_am824 *p = s->protocol;
133
134 if (index < p->pcm_channels)
135 p->pcm_positions[index] = position;
136}
137EXPORT_SYMBOL_GPL(amdtp_am824_set_pcm_position);
138
139/**
140 * amdtp_am824_set_midi_position - set a index of data channel for MIDI
141 * conformant data channel
142 * @s: the AMDTP stream
143 * @position: the index of data channel in an data block
144 */
145void amdtp_am824_set_midi_position(struct amdtp_stream *s,
146 unsigned int position)
147{
148 struct amdtp_am824 *p = s->protocol;
149
150 p->midi_position = position;
151}
152EXPORT_SYMBOL_GPL(amdtp_am824_set_midi_position);
153
154static void write_pcm_s32(struct amdtp_stream *s,
155 struct snd_pcm_substream *pcm,
156 __be32 *buffer, unsigned int frames)
157{
158 struct amdtp_am824 *p = s->protocol;
159 struct snd_pcm_runtime *runtime = pcm->runtime;
160 unsigned int channels, remaining_frames, i, c;
161 const u32 *src;
162
163 channels = p->pcm_channels;
164 src = (void *)runtime->dma_area +
165 frames_to_bytes(runtime, s->pcm_buffer_pointer);
166 remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
167
168 for (i = 0; i < frames; ++i) {
169 for (c = 0; c < channels; ++c) {
170 buffer[p->pcm_positions[c]] =
171 cpu_to_be32((*src >> 8) | 0x40000000);
172 src++;
173 }
174 buffer += s->data_block_quadlets;
175 if (--remaining_frames == 0)
176 src = (void *)runtime->dma_area;
177 }
178}
179
180static void write_pcm_s16(struct amdtp_stream *s,
181 struct snd_pcm_substream *pcm,
182 __be32 *buffer, unsigned int frames)
183{
184 struct amdtp_am824 *p = s->protocol;
185 struct snd_pcm_runtime *runtime = pcm->runtime;
186 unsigned int channels, remaining_frames, i, c;
187 const u16 *src;
188
189 channels = p->pcm_channels;
190 src = (void *)runtime->dma_area +
191 frames_to_bytes(runtime, s->pcm_buffer_pointer);
192 remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
193
194 for (i = 0; i < frames; ++i) {
195 for (c = 0; c < channels; ++c) {
196 buffer[p->pcm_positions[c]] =
197 cpu_to_be32((*src << 8) | 0x42000000);
198 src++;
199 }
200 buffer += s->data_block_quadlets;
201 if (--remaining_frames == 0)
202 src = (void *)runtime->dma_area;
203 }
204}
205
206static void read_pcm_s32(struct amdtp_stream *s,
207 struct snd_pcm_substream *pcm,
208 __be32 *buffer, unsigned int frames)
209{
210 struct amdtp_am824 *p = s->protocol;
211 struct snd_pcm_runtime *runtime = pcm->runtime;
212 unsigned int channels, remaining_frames, i, c;
213 u32 *dst;
214
215 channels = p->pcm_channels;
216 dst = (void *)runtime->dma_area +
217 frames_to_bytes(runtime, s->pcm_buffer_pointer);
218 remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
219
220 for (i = 0; i < frames; ++i) {
221 for (c = 0; c < channels; ++c) {
222 *dst = be32_to_cpu(buffer[p->pcm_positions[c]]) << 8;
223 dst++;
224 }
225 buffer += s->data_block_quadlets;
226 if (--remaining_frames == 0)
227 dst = (void *)runtime->dma_area;
228 }
229}
230
231static void write_pcm_silence(struct amdtp_stream *s,
232 __be32 *buffer, unsigned int frames)
233{
234 struct amdtp_am824 *p = s->protocol;
235 unsigned int i, c, channels = p->pcm_channels;
236
237 for (i = 0; i < frames; ++i) {
238 for (c = 0; c < channels; ++c)
239 buffer[p->pcm_positions[c]] = cpu_to_be32(0x40000000);
240 buffer += s->data_block_quadlets;
241 }
242}
243
244/**
245 * amdtp_am824_set_pcm_format - set the PCM format
246 * @s: the AMDTP stream to configure
247 * @format: the format of the ALSA PCM device
248 *
249 * The sample format must be set after the other parameters (rate/PCM channels/
250 * MIDI) and before the stream is started, and must not be changed while the
251 * stream is running.
252 */
253void amdtp_am824_set_pcm_format(struct amdtp_stream *s, snd_pcm_format_t format)
254{
255 struct amdtp_am824 *p = s->protocol;
256
257 if (WARN_ON(amdtp_stream_pcm_running(s)))
258 return;
259
260 switch (format) {
261 default:
262 WARN_ON(1);
263 /* fall through */
264 case SNDRV_PCM_FORMAT_S16:
265 if (s->direction == AMDTP_OUT_STREAM) {
266 p->transfer_samples = write_pcm_s16;
267 break;
268 }
269 WARN_ON(1);
270 /* fall through */
271 case SNDRV_PCM_FORMAT_S32:
272 if (s->direction == AMDTP_OUT_STREAM)
273 p->transfer_samples = write_pcm_s32;
274 else
275 p->transfer_samples = read_pcm_s32;
276 break;
277 }
278}
279EXPORT_SYMBOL_GPL(amdtp_am824_set_pcm_format);
280
281/**
282 * amdtp_am824_add_pcm_hw_constraints - add hw constraints for PCM substream
283 * @s: the AMDTP stream for AM824 data block, must be initialized.
284 * @runtime: the PCM substream runtime
285 *
286 */
287int amdtp_am824_add_pcm_hw_constraints(struct amdtp_stream *s,
288 struct snd_pcm_runtime *runtime)
289{
290 int err;
291
292 err = amdtp_stream_add_pcm_hw_constraints(s, runtime);
293 if (err < 0)
294 return err;
295
296 /* AM824 in IEC 61883-6 can deliver 24bit data. */
297 return snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
298}
299EXPORT_SYMBOL_GPL(amdtp_am824_add_pcm_hw_constraints);
300
301/**
302 * amdtp_am824_midi_trigger - start/stop playback/capture with a MIDI device
303 * @s: the AMDTP stream
304 * @port: index of MIDI port
305 * @midi: the MIDI device to be started, or %NULL to stop the current device
306 *
307 * Call this function on a running isochronous stream to enable the actual
308 * transmission of MIDI data. This function should be called from the MIDI
309 * device's .trigger callback.
310 */
311void amdtp_am824_midi_trigger(struct amdtp_stream *s, unsigned int port,
312 struct snd_rawmidi_substream *midi)
313{
314 struct amdtp_am824 *p = s->protocol;
315
316 if (port < p->midi_ports)
317 ACCESS_ONCE(p->midi[port]) = midi;
318}
319EXPORT_SYMBOL_GPL(amdtp_am824_midi_trigger);
320
321/*
322 * To avoid sending MIDI bytes at too high a rate, assume that the receiving
323 * device has a FIFO, and track how much it is filled. This values increases
324 * by one whenever we send one byte in a packet, but the FIFO empties at
325 * a constant rate independent of our packet rate. One packet has syt_interval
326 * samples, so the number of bytes that empty out of the FIFO, per packet(!),
327 * is MIDI_BYTES_PER_SECOND * syt_interval / sample_rate. To avoid storing
328 * fractional values, the values in midi_fifo_used[] are measured in bytes
329 * multiplied by the sample rate.
330 */
331static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port)
332{
333 struct amdtp_am824 *p = s->protocol;
334 int used;
335
336 used = p->midi_fifo_used[port];
337 if (used == 0) /* common shortcut */
338 return true;
339
340 used -= MIDI_BYTES_PER_SECOND * s->syt_interval;
341 used = max(used, 0);
342 p->midi_fifo_used[port] = used;
343
344 return used < p->midi_fifo_limit;
345}
346
347static void midi_rate_use_one_byte(struct amdtp_stream *s, unsigned int port)
348{
349 struct amdtp_am824 *p = s->protocol;
350
351 p->midi_fifo_used[port] += amdtp_rate_table[s->sfc];
352}
353
354static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,
355 unsigned int frames)
356{
357 struct amdtp_am824 *p = s->protocol;
358 unsigned int f, port;
359 u8 *b;
360
361 for (f = 0; f < frames; f++) {
362 b = (u8 *)&buffer[p->midi_position];
363
364 port = (s->data_block_counter + f) % 8;
365 if (f < MAX_MIDI_RX_BLOCKS &&
366 midi_ratelimit_per_packet(s, port) &&
367 p->midi[port] != NULL &&
368 snd_rawmidi_transmit(p->midi[port], &b[1], 1) == 1) {
369 midi_rate_use_one_byte(s, port);
370 b[0] = 0x81;
371 } else {
372 b[0] = 0x80;
373 b[1] = 0;
374 }
375 b[2] = 0;
376 b[3] = 0;
377
378 buffer += s->data_block_quadlets;
379 }
380}
381
382static void read_midi_messages(struct amdtp_stream *s,
383 __be32 *buffer, unsigned int frames)
384{
385 struct amdtp_am824 *p = s->protocol;
386 unsigned int f, port;
387 int len;
388 u8 *b;
389
390 for (f = 0; f < frames; f++) {
391 port = (s->data_block_counter + f) % 8;
392 b = (u8 *)&buffer[p->midi_position];
393
394 len = b[0] - 0x80;
395 if ((1 <= len) && (len <= 3) && (p->midi[port]))
396 snd_rawmidi_receive(p->midi[port], b + 1, len);
397
398 buffer += s->data_block_quadlets;
399 }
400}
401
402static unsigned int process_rx_data_blocks(struct amdtp_stream *s, __be32 *buffer,
403 unsigned int data_blocks, unsigned int *syt)
404{
405 struct amdtp_am824 *p = s->protocol;
406 struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
407 unsigned int pcm_frames;
408
409 if (pcm) {
410 p->transfer_samples(s, pcm, buffer, data_blocks);
411 pcm_frames = data_blocks * p->frame_multiplier;
412 } else {
413 write_pcm_silence(s, buffer, data_blocks);
414 pcm_frames = 0;
415 }
416
417 if (p->midi_ports)
418 write_midi_messages(s, buffer, data_blocks);
419
420 return pcm_frames;
421}
422
423static unsigned int process_tx_data_blocks(struct amdtp_stream *s, __be32 *buffer,
424 unsigned int data_blocks, unsigned int *syt)
425{
426 struct amdtp_am824 *p = s->protocol;
427 struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
428 unsigned int pcm_frames;
429
430 if (pcm) {
431 p->transfer_samples(s, pcm, buffer, data_blocks);
432 pcm_frames = data_blocks * p->frame_multiplier;
433 } else {
434 pcm_frames = 0;
435 }
436
437 if (p->midi_ports)
438 read_midi_messages(s, buffer, data_blocks);
439
440 return pcm_frames;
441}
442
443/**
444 * amdtp_am824_init - initialize an AMDTP stream structure to handle AM824
445 * data block
446 * @s: the AMDTP stream to initialize
447 * @unit: the target of the stream
448 * @dir: the direction of stream
449 * @flags: the packet transmission method to use
450 */
451int amdtp_am824_init(struct amdtp_stream *s, struct fw_unit *unit,
452 enum amdtp_stream_direction dir, enum cip_flags flags)
453{
454 amdtp_stream_process_data_blocks_t process_data_blocks;
455
456 if (dir == AMDTP_IN_STREAM)
457 process_data_blocks = process_tx_data_blocks;
458 else
459 process_data_blocks = process_rx_data_blocks;
460
461 return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,
462 process_data_blocks,
463 sizeof(struct amdtp_am824));
464}
465EXPORT_SYMBOL_GPL(amdtp_am824_init);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * AM824 format in Audio and Music Data Transmission Protocol (IEC 61883-6)
4 *
5 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
6 * Copyright (c) 2015 Takashi Sakamoto <o-takashi@sakamocchi.jp>
7 */
8
9#include <linux/slab.h>
10
11#include "amdtp-am824.h"
12
13#define CIP_FMT_AM 0x10
14
15/* "Clock-based rate control mode" is just supported. */
16#define AMDTP_FDF_AM824 0x00
17
18/*
19 * Nominally 3125 bytes/second, but the MIDI port's clock might be
20 * 1% too slow, and the bus clock 100 ppm too fast.
21 */
22#define MIDI_BYTES_PER_SECOND 3093
23
24/*
25 * Several devices look only at the first eight data blocks.
26 * In any case, this is more than enough for the MIDI data rate.
27 */
28#define MAX_MIDI_RX_BLOCKS 8
29
30struct amdtp_am824 {
31 struct snd_rawmidi_substream *midi[AM824_MAX_CHANNELS_FOR_MIDI * 8];
32 int midi_fifo_limit;
33 int midi_fifo_used[AM824_MAX_CHANNELS_FOR_MIDI * 8];
34 unsigned int pcm_channels;
35 unsigned int midi_ports;
36
37 u8 pcm_positions[AM824_MAX_CHANNELS_FOR_PCM];
38 u8 midi_position;
39};
40
41/**
42 * amdtp_am824_set_parameters - set stream parameters
43 * @s: the AMDTP stream to configure
44 * @rate: the sample rate
45 * @pcm_channels: the number of PCM samples in each data block, to be encoded
46 * as AM824 multi-bit linear audio
47 * @midi_ports: the number of MIDI ports (i.e., MPX-MIDI Data Channels)
48 * @double_pcm_frames: one data block transfers two PCM frames
49 *
50 * The parameters must be set before the stream is started, and must not be
51 * changed while the stream is running.
52 */
53int amdtp_am824_set_parameters(struct amdtp_stream *s, unsigned int rate,
54 unsigned int pcm_channels,
55 unsigned int midi_ports,
56 bool double_pcm_frames)
57{
58 struct amdtp_am824 *p = s->protocol;
59 unsigned int midi_channels;
60 unsigned int pcm_frame_multiplier;
61 int i, err;
62
63 if (amdtp_stream_running(s))
64 return -EINVAL;
65
66 if (pcm_channels > AM824_MAX_CHANNELS_FOR_PCM)
67 return -EINVAL;
68
69 midi_channels = DIV_ROUND_UP(midi_ports, 8);
70 if (midi_channels > AM824_MAX_CHANNELS_FOR_MIDI)
71 return -EINVAL;
72
73 if (WARN_ON(amdtp_stream_running(s)) ||
74 WARN_ON(pcm_channels > AM824_MAX_CHANNELS_FOR_PCM) ||
75 WARN_ON(midi_channels > AM824_MAX_CHANNELS_FOR_MIDI))
76 return -EINVAL;
77
78 /*
79 * In IEC 61883-6, one data block represents one event. In ALSA, one
80 * event equals to one PCM frame. But Dice has a quirk at higher
81 * sampling rate to transfer two PCM frames in one data block.
82 */
83 if (double_pcm_frames)
84 pcm_frame_multiplier = 2;
85 else
86 pcm_frame_multiplier = 1;
87
88 err = amdtp_stream_set_parameters(s, rate, pcm_channels + midi_channels,
89 pcm_frame_multiplier);
90 if (err < 0)
91 return err;
92
93 if (s->direction == AMDTP_OUT_STREAM)
94 s->ctx_data.rx.fdf = AMDTP_FDF_AM824 | s->sfc;
95
96 p->pcm_channels = pcm_channels;
97 p->midi_ports = midi_ports;
98
99 /* init the position map for PCM and MIDI channels */
100 for (i = 0; i < pcm_channels; i++)
101 p->pcm_positions[i] = i;
102 p->midi_position = p->pcm_channels;
103
104 /*
105 * We do not know the actual MIDI FIFO size of most devices. Just
106 * assume two bytes, i.e., one byte can be received over the bus while
107 * the previous one is transmitted over MIDI.
108 * (The value here is adjusted for midi_ratelimit_per_packet().)
109 */
110 p->midi_fifo_limit = rate - MIDI_BYTES_PER_SECOND * s->syt_interval + 1;
111
112 return 0;
113}
114EXPORT_SYMBOL_GPL(amdtp_am824_set_parameters);
115
116/**
117 * amdtp_am824_set_pcm_position - set an index of data channel for a channel
118 * of PCM frame
119 * @s: the AMDTP stream
120 * @index: the index of data channel in an data block
121 * @position: the channel of PCM frame
122 */
123void amdtp_am824_set_pcm_position(struct amdtp_stream *s, unsigned int index,
124 unsigned int position)
125{
126 struct amdtp_am824 *p = s->protocol;
127
128 if (index < p->pcm_channels)
129 p->pcm_positions[index] = position;
130}
131EXPORT_SYMBOL_GPL(amdtp_am824_set_pcm_position);
132
133/**
134 * amdtp_am824_set_midi_position - set a index of data channel for MIDI
135 * conformant data channel
136 * @s: the AMDTP stream
137 * @position: the index of data channel in an data block
138 */
139void amdtp_am824_set_midi_position(struct amdtp_stream *s,
140 unsigned int position)
141{
142 struct amdtp_am824 *p = s->protocol;
143
144 p->midi_position = position;
145}
146EXPORT_SYMBOL_GPL(amdtp_am824_set_midi_position);
147
148static void write_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
149 __be32 *buffer, unsigned int frames,
150 unsigned int pcm_frames)
151{
152 struct amdtp_am824 *p = s->protocol;
153 unsigned int channels = p->pcm_channels;
154 struct snd_pcm_runtime *runtime = pcm->runtime;
155 unsigned int pcm_buffer_pointer;
156 int remaining_frames;
157 const u32 *src;
158 int i, c;
159
160 pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;
161 pcm_buffer_pointer %= runtime->buffer_size;
162
163 src = (void *)runtime->dma_area +
164 frames_to_bytes(runtime, pcm_buffer_pointer);
165 remaining_frames = runtime->buffer_size - pcm_buffer_pointer;
166
167 for (i = 0; i < frames; ++i) {
168 for (c = 0; c < channels; ++c) {
169 buffer[p->pcm_positions[c]] =
170 cpu_to_be32((*src >> 8) | 0x40000000);
171 src++;
172 }
173 buffer += s->data_block_quadlets;
174 if (--remaining_frames == 0)
175 src = (void *)runtime->dma_area;
176 }
177}
178
179static void read_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
180 __be32 *buffer, unsigned int frames,
181 unsigned int pcm_frames)
182{
183 struct amdtp_am824 *p = s->protocol;
184 unsigned int channels = p->pcm_channels;
185 struct snd_pcm_runtime *runtime = pcm->runtime;
186 unsigned int pcm_buffer_pointer;
187 int remaining_frames;
188 u32 *dst;
189 int i, c;
190
191 pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;
192 pcm_buffer_pointer %= runtime->buffer_size;
193
194 dst = (void *)runtime->dma_area +
195 frames_to_bytes(runtime, pcm_buffer_pointer);
196 remaining_frames = runtime->buffer_size - pcm_buffer_pointer;
197
198 for (i = 0; i < frames; ++i) {
199 for (c = 0; c < channels; ++c) {
200 *dst = be32_to_cpu(buffer[p->pcm_positions[c]]) << 8;
201 dst++;
202 }
203 buffer += s->data_block_quadlets;
204 if (--remaining_frames == 0)
205 dst = (void *)runtime->dma_area;
206 }
207}
208
209static void write_pcm_silence(struct amdtp_stream *s,
210 __be32 *buffer, unsigned int frames)
211{
212 struct amdtp_am824 *p = s->protocol;
213 unsigned int i, c, channels = p->pcm_channels;
214
215 for (i = 0; i < frames; ++i) {
216 for (c = 0; c < channels; ++c)
217 buffer[p->pcm_positions[c]] = cpu_to_be32(0x40000000);
218 buffer += s->data_block_quadlets;
219 }
220}
221
222/**
223 * amdtp_am824_add_pcm_hw_constraints - add hw constraints for PCM substream
224 * @s: the AMDTP stream for AM824 data block, must be initialized.
225 * @runtime: the PCM substream runtime
226 *
227 */
228int amdtp_am824_add_pcm_hw_constraints(struct amdtp_stream *s,
229 struct snd_pcm_runtime *runtime)
230{
231 int err;
232
233 err = amdtp_stream_add_pcm_hw_constraints(s, runtime);
234 if (err < 0)
235 return err;
236
237 /* AM824 in IEC 61883-6 can deliver 24bit data. */
238 return snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
239}
240EXPORT_SYMBOL_GPL(amdtp_am824_add_pcm_hw_constraints);
241
242/**
243 * amdtp_am824_midi_trigger - start/stop playback/capture with a MIDI device
244 * @s: the AMDTP stream
245 * @port: index of MIDI port
246 * @midi: the MIDI device to be started, or %NULL to stop the current device
247 *
248 * Call this function on a running isochronous stream to enable the actual
249 * transmission of MIDI data. This function should be called from the MIDI
250 * device's .trigger callback.
251 */
252void amdtp_am824_midi_trigger(struct amdtp_stream *s, unsigned int port,
253 struct snd_rawmidi_substream *midi)
254{
255 struct amdtp_am824 *p = s->protocol;
256
257 if (port < p->midi_ports)
258 WRITE_ONCE(p->midi[port], midi);
259}
260EXPORT_SYMBOL_GPL(amdtp_am824_midi_trigger);
261
262/*
263 * To avoid sending MIDI bytes at too high a rate, assume that the receiving
264 * device has a FIFO, and track how much it is filled. This values increases
265 * by one whenever we send one byte in a packet, but the FIFO empties at
266 * a constant rate independent of our packet rate. One packet has syt_interval
267 * samples, so the number of bytes that empty out of the FIFO, per packet(!),
268 * is MIDI_BYTES_PER_SECOND * syt_interval / sample_rate. To avoid storing
269 * fractional values, the values in midi_fifo_used[] are measured in bytes
270 * multiplied by the sample rate.
271 */
272static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port)
273{
274 struct amdtp_am824 *p = s->protocol;
275 int used;
276
277 used = p->midi_fifo_used[port];
278 if (used == 0) /* common shortcut */
279 return true;
280
281 used -= MIDI_BYTES_PER_SECOND * s->syt_interval;
282 used = max(used, 0);
283 p->midi_fifo_used[port] = used;
284
285 return used < p->midi_fifo_limit;
286}
287
288static void midi_rate_use_one_byte(struct amdtp_stream *s, unsigned int port)
289{
290 struct amdtp_am824 *p = s->protocol;
291
292 p->midi_fifo_used[port] += amdtp_rate_table[s->sfc];
293}
294
295static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,
296 unsigned int frames, unsigned int data_block_counter)
297{
298 struct amdtp_am824 *p = s->protocol;
299 unsigned int f, port;
300 u8 *b;
301
302 for (f = 0; f < frames; f++) {
303 b = (u8 *)&buffer[p->midi_position];
304
305 port = (data_block_counter + f) % 8;
306 if (f < MAX_MIDI_RX_BLOCKS &&
307 midi_ratelimit_per_packet(s, port) &&
308 p->midi[port] != NULL &&
309 snd_rawmidi_transmit(p->midi[port], &b[1], 1) == 1) {
310 midi_rate_use_one_byte(s, port);
311 b[0] = 0x81;
312 } else {
313 b[0] = 0x80;
314 b[1] = 0;
315 }
316 b[2] = 0;
317 b[3] = 0;
318
319 buffer += s->data_block_quadlets;
320 }
321}
322
323static void read_midi_messages(struct amdtp_stream *s, __be32 *buffer,
324 unsigned int frames, unsigned int data_block_counter)
325{
326 struct amdtp_am824 *p = s->protocol;
327 int len;
328 u8 *b;
329 int f;
330
331 for (f = 0; f < frames; f++) {
332 unsigned int port = f;
333
334 if (!(s->flags & CIP_UNALIGHED_DBC))
335 port += data_block_counter;
336 port %= 8;
337 b = (u8 *)&buffer[p->midi_position];
338
339 len = b[0] - 0x80;
340 if ((1 <= len) && (len <= 3) && (p->midi[port]))
341 snd_rawmidi_receive(p->midi[port], b + 1, len);
342
343 buffer += s->data_block_quadlets;
344 }
345}
346
347static void process_it_ctx_payloads(struct amdtp_stream *s, const struct pkt_desc *desc,
348 unsigned int count, struct snd_pcm_substream *pcm)
349{
350 struct amdtp_am824 *p = s->protocol;
351 unsigned int pcm_frames = 0;
352 int i;
353
354 for (i = 0; i < count; ++i) {
355 __be32 *buf = desc->ctx_payload;
356 unsigned int data_blocks = desc->data_blocks;
357
358 if (pcm) {
359 write_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);
360 pcm_frames += data_blocks * s->pcm_frame_multiplier;
361 } else {
362 write_pcm_silence(s, buf, data_blocks);
363 }
364
365 if (p->midi_ports) {
366 write_midi_messages(s, buf, data_blocks,
367 desc->data_block_counter);
368 }
369
370 desc = amdtp_stream_next_packet_desc(s, desc);
371 }
372}
373
374static void process_ir_ctx_payloads(struct amdtp_stream *s, const struct pkt_desc *desc,
375 unsigned int count, struct snd_pcm_substream *pcm)
376{
377 struct amdtp_am824 *p = s->protocol;
378 unsigned int pcm_frames = 0;
379 int i;
380
381 for (i = 0; i < count; ++i) {
382 __be32 *buf = desc->ctx_payload;
383 unsigned int data_blocks = desc->data_blocks;
384
385 if (pcm) {
386 read_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);
387 pcm_frames += data_blocks * s->pcm_frame_multiplier;
388 }
389
390 if (p->midi_ports) {
391 read_midi_messages(s, buf, data_blocks,
392 desc->data_block_counter);
393 }
394
395 desc = amdtp_stream_next_packet_desc(s, desc);
396 }
397}
398
399/**
400 * amdtp_am824_init - initialize an AMDTP stream structure to handle AM824
401 * data block
402 * @s: the AMDTP stream to initialize
403 * @unit: the target of the stream
404 * @dir: the direction of stream
405 * @flags: the details of the streaming protocol consist of cip_flags enumeration-constants.
406 */
407int amdtp_am824_init(struct amdtp_stream *s, struct fw_unit *unit,
408 enum amdtp_stream_direction dir, unsigned int flags)
409{
410 amdtp_stream_process_ctx_payloads_t process_ctx_payloads;
411
412 if (dir == AMDTP_IN_STREAM)
413 process_ctx_payloads = process_ir_ctx_payloads;
414 else
415 process_ctx_payloads = process_it_ctx_payloads;
416
417 return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,
418 process_ctx_payloads, sizeof(struct amdtp_am824));
419}
420EXPORT_SYMBOL_GPL(amdtp_am824_init);