summaryrefslogtreecommitdiffstats
path: root/sound/firewire/amdtp-am824.c
blob: fd5d6b8ac557aa57035ddd66b0a83ba7dc7ea8bd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
// SPDX-License-Identifier: GPL-2.0-only
/*
 * AM824 format in Audio and Music Data Transmission Protocol (IEC 61883-6)
 *
 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
 * Copyright (c) 2015 Takashi Sakamoto <o-takashi@sakamocchi.jp>
 */

#include <linux/slab.h>

#include "amdtp-am824.h"

#define CIP_FMT_AM		0x10

/* "Clock-based rate control mode" is just supported. */
#define AMDTP_FDF_AM824		0x00

/*
 * Nominally 3125 bytes/second, but the MIDI port's clock might be
 * 1% too slow, and the bus clock 100 ppm too fast.
 */
#define MIDI_BYTES_PER_SECOND	3093

/*
 * Several devices look only at the first eight data blocks.
 * In any case, this is more than enough for the MIDI data rate.
 */
#define MAX_MIDI_RX_BLOCKS	8

struct amdtp_am824 {
	struct snd_rawmidi_substream *midi[AM824_MAX_CHANNELS_FOR_MIDI * 8];
	int midi_fifo_limit;
	int midi_fifo_used[AM824_MAX_CHANNELS_FOR_MIDI * 8];
	unsigned int pcm_channels;
	unsigned int midi_ports;

	u8 pcm_positions[AM824_MAX_CHANNELS_FOR_PCM];
	u8 midi_position;

	unsigned int frame_multiplier;
};

/**
 * amdtp_am824_set_parameters - set stream parameters
 * @s: the AMDTP stream to configure
 * @rate: the sample rate
 * @pcm_channels: the number of PCM samples in each data block, to be encoded
 *                as AM824 multi-bit linear audio
 * @midi_ports: the number of MIDI ports (i.e., MPX-MIDI Data Channels)
 * @double_pcm_frames: one data block transfers two PCM frames
 *
 * The parameters must be set before the stream is started, and must not be
 * changed while the stream is running.
 */
int amdtp_am824_set_parameters(struct amdtp_stream *s, unsigned int rate,
			       unsigned int pcm_channels,
			       unsigned int midi_ports,
			       bool double_pcm_frames)
{
	struct amdtp_am824 *p = s->protocol;
	unsigned int midi_channels;
	unsigned int i;
	int err;

	if (amdtp_stream_running(s))
		return -EINVAL;

	if (pcm_channels > AM824_MAX_CHANNELS_FOR_PCM)
		return -EINVAL;

	midi_channels = DIV_ROUND_UP(midi_ports, 8);
	if (midi_channels > AM824_MAX_CHANNELS_FOR_MIDI)
		return -EINVAL;

	if (WARN_ON(amdtp_stream_running(s)) ||
	    WARN_ON(pcm_channels > AM824_MAX_CHANNELS_FOR_PCM) ||
	    WARN_ON(midi_channels > AM824_MAX_CHANNELS_FOR_MIDI))
		return -EINVAL;

	err = amdtp_stream_set_parameters(s, rate,
					  pcm_channels + midi_channels);
	if (err < 0)
		return err;

	s->ctx_data.rx.fdf = AMDTP_FDF_AM824 | s->sfc;

	p->pcm_channels = pcm_channels;
	p->midi_ports = midi_ports;

	/*
	 * In IEC 61883-6, one data block represents one event. In ALSA, one
	 * event equals to one PCM frame. But Dice has a quirk at higher
	 * sampling rate to transfer two PCM frames in one data block.
	 */
	if (double_pcm_frames)
		p->frame_multiplier = 2;
	else
		p->frame_multiplier = 1;

	/* init the position map for PCM and MIDI channels */
	for (i = 0; i < pcm_channels; i++)
		p->pcm_positions[i] = i;
	p->midi_position = p->pcm_channels;

	/*
	 * We do not know the actual MIDI FIFO size of most devices.  Just
	 * assume two bytes, i.e., one byte can be received over the bus while
	 * the previous one is transmitted over MIDI.
	 * (The value here is adjusted for midi_ratelimit_per_packet().)
	 */
	p->midi_fifo_limit = rate - MIDI_BYTES_PER_SECOND * s->syt_interval + 1;

	return 0;
}
EXPORT_SYMBOL_GPL(amdtp_am824_set_parameters);

/**
 * amdtp_am824_set_pcm_position - set an index of data channel for a channel
 *				  of PCM frame
 * @s: the AMDTP stream
 * @index: the index of data channel in an data block
 * @position: the channel of PCM frame
 */
void amdtp_am824_set_pcm_position(struct amdtp_stream *s, unsigned int index,
				 unsigned int position)
{
	struct amdtp_am824 *p = s->protocol;

	if (index < p->pcm_channels)
		p->pcm_positions[index] = position;
}
EXPORT_SYMBOL_GPL(amdtp_am824_set_pcm_position);

/**
 * amdtp_am824_set_midi_position - set a index of data channel for MIDI
 *				   conformant data channel
 * @s: the AMDTP stream
 * @position: the index of data channel in an data block
 */
void amdtp_am824_set_midi_position(struct amdtp_stream *s,
				   unsigned int position)
{
	struct amdtp_am824 *p = s->protocol;

	p->midi_position = position;
}
EXPORT_SYMBOL_GPL(amdtp_am824_set_midi_position);

static void write_pcm_s32(struct amdtp_stream *s,
			  struct snd_pcm_substream *pcm,
			  __be32 *buffer, unsigned int frames)
{
	struct amdtp_am824 *p = s->protocol;
	struct snd_pcm_runtime *runtime = pcm->runtime;
	unsigned int channels, remaining_frames, i, c;
	const u32 *src;

	channels = p->pcm_channels;
	src = (void *)runtime->dma_area +
			frames_to_bytes(runtime, s->pcm_buffer_pointer);
	remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;

	for (i = 0; i < frames; ++i) {
		for (c = 0; c < channels; ++c) {
			buffer[p->pcm_positions[c]] =
					cpu_to_be32((*src >> 8) | 0x40000000);
			src++;
		}
		buffer += s->data_block_quadlets;
		if (--remaining_frames == 0)
			src = (void *)runtime->dma_area;
	}
}

static void read_pcm_s32(struct amdtp_stream *s,
			 struct snd_pcm_substream *pcm,
			 __be32 *buffer, unsigned int frames)
{
	struct amdtp_am824 *p = s->protocol;
	struct snd_pcm_runtime *runtime = pcm->runtime;
	unsigned int channels, remaining_frames, i, c;
	u32 *dst;

	channels = p->pcm_channels;
	dst  = (void *)runtime->dma_area +
			frames_to_bytes(runtime, s->pcm_buffer_pointer);
	remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;

	for (i = 0; i < frames; ++i) {
		for (c = 0; c < channels; ++c) {
			*dst = be32_to_cpu(buffer[p->pcm_positions[c]]) << 8;
			dst++;
		}
		buffer += s->data_block_quadlets;
		if (--remaining_frames == 0)
			dst = (void *)runtime->dma_area;
	}
}

static void write_pcm_silence(struct amdtp_stream *s,
			      __be32 *buffer, unsigned int frames)
{
	struct amdtp_am824 *p = s->protocol;
	unsigned int i, c, channels = p->pcm_channels;

	for (i = 0; i < frames; ++i) {
		for (c = 0; c < channels; ++c)
			buffer[p->pcm_positions[c]] = cpu_to_be32(0x40000000);
		buffer += s->data_block_quadlets;
	}
}

/**
 * amdtp_am824_add_pcm_hw_constraints - add hw constraints for PCM substream
 * @s:		the AMDTP stream for AM824 data block, must be initialized.
 * @runtime:	the PCM substream runtime
 *
 */
int amdtp_am824_add_pcm_hw_constraints(struct amdtp_stream *s,
				       struct snd_pcm_runtime *runtime)
{
	int err;

	err = amdtp_stream_add_pcm_hw_constraints(s, runtime);
	if (err < 0)
		return err;

	/* AM824 in IEC 61883-6 can deliver 24bit data. */
	return snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
}
EXPORT_SYMBOL_GPL(amdtp_am824_add_pcm_hw_constraints);

/**
 * amdtp_am824_midi_trigger - start/stop playback/capture with a MIDI device
 * @s: the AMDTP stream
 * @port: index of MIDI port
 * @midi: the MIDI device to be started, or %NULL to stop the current device
 *
 * Call this function on a running isochronous stream to enable the actual
 * transmission of MIDI data.  This function should be called from the MIDI
 * device's .trigger callback.
 */
void amdtp_am824_midi_trigger(struct amdtp_stream *s, unsigned int port,
			      struct snd_rawmidi_substream *midi)
{
	struct amdtp_am824 *p = s->protocol;

	if (port < p->midi_ports)
		WRITE_ONCE(p->midi[port], midi);
}
EXPORT_SYMBOL_GPL(amdtp_am824_midi_trigger);

/*
 * To avoid sending MIDI bytes at too high a rate, assume that the receiving
 * device has a FIFO, and track how much it is filled.  This values increases
 * by one whenever we send one byte in a packet, but the FIFO empties at
 * a constant rate independent of our packet rate.  One packet has syt_interval
 * samples, so the number of bytes that empty out of the FIFO, per packet(!),
 * is MIDI_BYTES_PER_SECOND * syt_interval / sample_rate.  To avoid storing
 * fractional values, the values in midi_fifo_used[] are measured in bytes
 * multiplied by the sample rate.
 */
static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port)
{
	struct amdtp_am824 *p = s->protocol;
	int used;

	used = p->midi_fifo_used[port];
	if (used == 0) /* common shortcut */
		return true;

	used -= MIDI_BYTES_PER_SECOND * s->syt_interval;
	used = max(used, 0);
	p->midi_fifo_used[port] = used;

	return used < p->midi_fifo_limit;
}

static void midi_rate_use_one_byte(struct amdtp_stream *s, unsigned int port)
{
	struct amdtp_am824 *p = s->protocol;

	p->midi_fifo_used[port] += amdtp_rate_table[s->sfc];
}

static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,
				unsigned int frames)
{
	struct amdtp_am824 *p = s->protocol;
	unsigned int f, port;
	u8 *b;

	for (f = 0; f < frames; f++) {
		b = (u8 *)&buffer[p->midi_position];

		port = (s->data_block_counter + f) % 8;
		if (f < MAX_MIDI_RX_BLOCKS &&
		    midi_ratelimit_per_packet(s, port) &&
		    p->midi[port] != NULL &&
		    snd_rawmidi_transmit(p->midi[port], &b[1], 1) == 1) {
			midi_rate_use_one_byte(s, port);
			b[0] = 0x81;
		} else {
			b[0] = 0x80;
			b[1] = 0;
		}
		b[2] = 0;
		b[3] = 0;

		buffer += s->data_block_quadlets;
	}
}

static void read_midi_messages(struct amdtp_stream *s,
			       __be32 *buffer, unsigned int frames)
{
	struct amdtp_am824 *p = s->protocol;
	unsigned int f, port;
	int len;
	u8 *b;

	for (f = 0; f < frames; f++) {
		port = (8 - s->ctx_data.tx.first_dbc + s->data_block_counter + f) % 8;
		b = (u8 *)&buffer[p->midi_position];

		len = b[0] - 0x80;
		if ((1 <= len) &&  (len <= 3) && (p->midi[port]))
			snd_rawmidi_receive(p->midi[port], b + 1, len);

		buffer += s->data_block_quadlets;
	}
}

static unsigned int process_rx_data_blocks(struct amdtp_stream *s, __be32 *buffer,
					   unsigned int data_blocks, unsigned int *syt)
{
	struct amdtp_am824 *p = s->protocol;
	struct snd_pcm_substream *pcm = READ_ONCE(s->pcm);
	unsigned int pcm_frames;

	if (pcm) {
		write_pcm_s32(s, pcm, buffer, data_blocks);
		pcm_frames = data_blocks * p->frame_multiplier;
	} else {
		write_pcm_silence(s, buffer, data_blocks);
		pcm_frames = 0;
	}

	if (p->midi_ports)
		write_midi_messages(s, buffer, data_blocks);

	return pcm_frames;
}

static unsigned int process_tx_data_blocks(struct amdtp_stream *s, __be32 *buffer,
					   unsigned int data_blocks, unsigned int *syt)
{
	struct amdtp_am824 *p = s->protocol;
	struct snd_pcm_substream *pcm = READ_ONCE(s->pcm);
	unsigned int pcm_frames;

	if (pcm) {
		read_pcm_s32(s, pcm, buffer, data_blocks);
		pcm_frames = data_blocks * p->frame_multiplier;
	} else {
		pcm_frames = 0;
	}

	if (p->midi_ports)
		read_midi_messages(s, buffer, data_blocks);

	return pcm_frames;
}

/**
 * amdtp_am824_init - initialize an AMDTP stream structure to handle AM824
 *		      data block
 * @s: the AMDTP stream to initialize
 * @unit: the target of the stream
 * @dir: the direction of stream
 * @flags: the packet transmission method to use
 */
int amdtp_am824_init(struct amdtp_stream *s, struct fw_unit *unit,
		     enum amdtp_stream_direction dir, enum cip_flags flags)
{
	amdtp_stream_process_data_blocks_t process_data_blocks;

	if (dir == AMDTP_IN_STREAM)
		process_data_blocks = process_tx_data_blocks;
	else
		process_data_blocks = process_rx_data_blocks;

	return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,
				 process_data_blocks,
				 sizeof(struct amdtp_am824));
}
EXPORT_SYMBOL_GPL(amdtp_am824_init);