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