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 	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  */
amdtp_am824_set_parameters(struct amdtp_stream * s,unsigned int rate,unsigned int pcm_channels,unsigned int midi_ports,bool double_pcm_frames)55 int 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 }
116 EXPORT_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  */
amdtp_am824_set_pcm_position(struct amdtp_stream * s,unsigned int index,unsigned int position)125 void 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 }
133 EXPORT_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  */
amdtp_am824_set_midi_position(struct amdtp_stream * s,unsigned int position)141 void 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 }
148 EXPORT_SYMBOL_GPL(amdtp_am824_set_midi_position);
149 
write_pcm_s32(struct amdtp_stream * s,struct snd_pcm_substream * pcm,__be32 * buffer,unsigned int frames,unsigned int pcm_frames)150 static 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 
read_pcm_s32(struct amdtp_stream * s,struct snd_pcm_substream * pcm,__be32 * buffer,unsigned int frames,unsigned int pcm_frames)181 static 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 
write_pcm_silence(struct amdtp_stream * s,__be32 * buffer,unsigned int frames)211 static 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  */
amdtp_am824_add_pcm_hw_constraints(struct amdtp_stream * s,struct snd_pcm_runtime * runtime)230 int 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 }
242 EXPORT_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  */
amdtp_am824_midi_trigger(struct amdtp_stream * s,unsigned int port,struct snd_rawmidi_substream * midi)254 void 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 }
262 EXPORT_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  */
midi_ratelimit_per_packet(struct amdtp_stream * s,unsigned int port)274 static 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 
midi_rate_use_one_byte(struct amdtp_stream * s,unsigned int port)290 static 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 
write_midi_messages(struct amdtp_stream * s,__be32 * buffer,unsigned int frames,unsigned int data_block_counter)297 static 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 
read_midi_messages(struct amdtp_stream * s,__be32 * buffer,unsigned int frames,unsigned int data_block_counter)325 static 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 
process_it_ctx_payloads(struct amdtp_stream * s,const struct pkt_desc * descs,unsigned int packets,struct snd_pcm_substream * pcm)349 static 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 
process_ir_ctx_payloads(struct amdtp_stream * s,const struct pkt_desc * descs,unsigned int packets,struct snd_pcm_substream * pcm)379 static 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  */
amdtp_am824_init(struct amdtp_stream * s,struct fw_unit * unit,enum amdtp_stream_direction dir,unsigned int flags)415 int 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 }
428 EXPORT_SYMBOL_GPL(amdtp_am824_init);
429