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
30 struct 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 */
53 int 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 }
114 EXPORT_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 */
123 void 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 }
131 EXPORT_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 */
139 void 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 }
146 EXPORT_SYMBOL_GPL(amdtp_am824_set_midi_position);
147
148 static 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
179 static 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
209 static 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 */
228 int 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 }
240 EXPORT_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 */
252 void 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 }
260 EXPORT_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 */
272 static 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
288 static 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
295 static 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
323 static 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
347 static 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
374 static 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 */
407 int 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 }
420 EXPORT_SYMBOL_GPL(amdtp_am824_init);
421
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