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Linux/sound/firewire/amdtp-am824.c

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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 
 31 struct 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         unsigned int frame_multiplier;
 42 };
 43 
 44 /**
 45  * amdtp_am824_set_parameters - set stream parameters
 46  * @s: the AMDTP stream to configure
 47  * @rate: the sample rate
 48  * @pcm_channels: the number of PCM samples in each data block, to be encoded
 49  *                as AM824 multi-bit linear audio
 50  * @midi_ports: the number of MIDI ports (i.e., MPX-MIDI Data Channels)
 51  * @double_pcm_frames: one data block transfers two PCM frames
 52  *
 53  * The parameters must be set before the stream is started, and must not be
 54  * changed while the stream is running.
 55  */
 56 int amdtp_am824_set_parameters(struct amdtp_stream *s, unsigned int rate,
 57                                unsigned int pcm_channels,
 58                                unsigned int midi_ports,
 59                                bool double_pcm_frames)
 60 {
 61         struct amdtp_am824 *p = s->protocol;
 62         unsigned int midi_channels;
 63         unsigned int i;
 64         int err;
 65 
 66         if (amdtp_stream_running(s))
 67                 return -EINVAL;
 68 
 69         if (pcm_channels > AM824_MAX_CHANNELS_FOR_PCM)
 70                 return -EINVAL;
 71 
 72         midi_channels = DIV_ROUND_UP(midi_ports, 8);
 73         if (midi_channels > AM824_MAX_CHANNELS_FOR_MIDI)
 74                 return -EINVAL;
 75 
 76         if (WARN_ON(amdtp_stream_running(s)) ||
 77             WARN_ON(pcm_channels > AM824_MAX_CHANNELS_FOR_PCM) ||
 78             WARN_ON(midi_channels > AM824_MAX_CHANNELS_FOR_MIDI))
 79                 return -EINVAL;
 80 
 81         err = amdtp_stream_set_parameters(s, rate,
 82                                           pcm_channels + midi_channels);
 83         if (err < 0)
 84                 return err;
 85 
 86         s->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  */
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  */
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 
150 static void write_pcm_s32(struct amdtp_stream *s,
151                           struct snd_pcm_substream *pcm,
152                           __be32 *buffer, unsigned int frames)
153 {
154         struct amdtp_am824 *p = s->protocol;
155         struct snd_pcm_runtime *runtime = pcm->runtime;
156         unsigned int channels, remaining_frames, i, c;
157         const u32 *src;
158 
159         channels = p->pcm_channels;
160         src = (void *)runtime->dma_area +
161                         frames_to_bytes(runtime, s->pcm_buffer_pointer);
162         remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
163 
164         for (i = 0; i < frames; ++i) {
165                 for (c = 0; c < channels; ++c) {
166                         buffer[p->pcm_positions[c]] =
167                                         cpu_to_be32((*src >> 8) | 0x40000000);
168                         src++;
169                 }
170                 buffer += s->data_block_quadlets;
171                 if (--remaining_frames == 0)
172                         src = (void *)runtime->dma_area;
173         }
174 }
175 
176 static void read_pcm_s32(struct amdtp_stream *s,
177                          struct snd_pcm_substream *pcm,
178                          __be32 *buffer, unsigned int frames)
179 {
180         struct amdtp_am824 *p = s->protocol;
181         struct snd_pcm_runtime *runtime = pcm->runtime;
182         unsigned int channels, remaining_frames, i, c;
183         u32 *dst;
184 
185         channels = p->pcm_channels;
186         dst  = (void *)runtime->dma_area +
187                         frames_to_bytes(runtime, s->pcm_buffer_pointer);
188         remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
189 
190         for (i = 0; i < frames; ++i) {
191                 for (c = 0; c < channels; ++c) {
192                         *dst = be32_to_cpu(buffer[p->pcm_positions[c]]) << 8;
193                         dst++;
194                 }
195                 buffer += s->data_block_quadlets;
196                 if (--remaining_frames == 0)
197                         dst = (void *)runtime->dma_area;
198         }
199 }
200 
201 static void write_pcm_silence(struct amdtp_stream *s,
202                               __be32 *buffer, unsigned int frames)
203 {
204         struct amdtp_am824 *p = s->protocol;
205         unsigned int i, c, channels = p->pcm_channels;
206 
207         for (i = 0; i < frames; ++i) {
208                 for (c = 0; c < channels; ++c)
209                         buffer[p->pcm_positions[c]] = cpu_to_be32(0x40000000);
210                 buffer += s->data_block_quadlets;
211         }
212 }
213 
214 /**
215  * amdtp_am824_add_pcm_hw_constraints - add hw constraints for PCM substream
216  * @s:          the AMDTP stream for AM824 data block, must be initialized.
217  * @runtime:    the PCM substream runtime
218  *
219  */
220 int amdtp_am824_add_pcm_hw_constraints(struct amdtp_stream *s,
221                                        struct snd_pcm_runtime *runtime)
222 {
223         int err;
224 
225         err = amdtp_stream_add_pcm_hw_constraints(s, runtime);
226         if (err < 0)
227                 return err;
228 
229         /* AM824 in IEC 61883-6 can deliver 24bit data. */
230         return snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
231 }
232 EXPORT_SYMBOL_GPL(amdtp_am824_add_pcm_hw_constraints);
233 
234 /**
235  * amdtp_am824_midi_trigger - start/stop playback/capture with a MIDI device
236  * @s: the AMDTP stream
237  * @port: index of MIDI port
238  * @midi: the MIDI device to be started, or %NULL to stop the current device
239  *
240  * Call this function on a running isochronous stream to enable the actual
241  * transmission of MIDI data.  This function should be called from the MIDI
242  * device's .trigger callback.
243  */
244 void amdtp_am824_midi_trigger(struct amdtp_stream *s, unsigned int port,
245                               struct snd_rawmidi_substream *midi)
246 {
247         struct amdtp_am824 *p = s->protocol;
248 
249         if (port < p->midi_ports)
250                 WRITE_ONCE(p->midi[port], midi);
251 }
252 EXPORT_SYMBOL_GPL(amdtp_am824_midi_trigger);
253 
254 /*
255  * To avoid sending MIDI bytes at too high a rate, assume that the receiving
256  * device has a FIFO, and track how much it is filled.  This values increases
257  * by one whenever we send one byte in a packet, but the FIFO empties at
258  * a constant rate independent of our packet rate.  One packet has syt_interval
259  * samples, so the number of bytes that empty out of the FIFO, per packet(!),
260  * is MIDI_BYTES_PER_SECOND * syt_interval / sample_rate.  To avoid storing
261  * fractional values, the values in midi_fifo_used[] are measured in bytes
262  * multiplied by the sample rate.
263  */
264 static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port)
265 {
266         struct amdtp_am824 *p = s->protocol;
267         int used;
268 
269         used = p->midi_fifo_used[port];
270         if (used == 0) /* common shortcut */
271                 return true;
272 
273         used -= MIDI_BYTES_PER_SECOND * s->syt_interval;
274         used = max(used, 0);
275         p->midi_fifo_used[port] = used;
276 
277         return used < p->midi_fifo_limit;
278 }
279 
280 static void midi_rate_use_one_byte(struct amdtp_stream *s, unsigned int port)
281 {
282         struct amdtp_am824 *p = s->protocol;
283 
284         p->midi_fifo_used[port] += amdtp_rate_table[s->sfc];
285 }
286 
287 static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,
288                                 unsigned int frames)
289 {
290         struct amdtp_am824 *p = s->protocol;
291         unsigned int f, port;
292         u8 *b;
293 
294         for (f = 0; f < frames; f++) {
295                 b = (u8 *)&buffer[p->midi_position];
296 
297                 port = (s->data_block_counter + f) % 8;
298                 if (f < MAX_MIDI_RX_BLOCKS &&
299                     midi_ratelimit_per_packet(s, port) &&
300                     p->midi[port] != NULL &&
301                     snd_rawmidi_transmit(p->midi[port], &b[1], 1) == 1) {
302                         midi_rate_use_one_byte(s, port);
303                         b[0] = 0x81;
304                 } else {
305                         b[0] = 0x80;
306                         b[1] = 0;
307                 }
308                 b[2] = 0;
309                 b[3] = 0;
310 
311                 buffer += s->data_block_quadlets;
312         }
313 }
314 
315 static void read_midi_messages(struct amdtp_stream *s,
316                                __be32 *buffer, unsigned int frames)
317 {
318         struct amdtp_am824 *p = s->protocol;
319         unsigned int f, port;
320         int len;
321         u8 *b;
322 
323         for (f = 0; f < frames; f++) {
324                 port = (s->data_block_counter + f) % 8;
325                 b = (u8 *)&buffer[p->midi_position];
326 
327                 len = b[0] - 0x80;
328                 if ((1 <= len) &&  (len <= 3) && (p->midi[port]))
329                         snd_rawmidi_receive(p->midi[port], b + 1, len);
330 
331                 buffer += s->data_block_quadlets;
332         }
333 }
334 
335 static unsigned int process_rx_data_blocks(struct amdtp_stream *s, __be32 *buffer,
336                                            unsigned int data_blocks, unsigned int *syt)
337 {
338         struct amdtp_am824 *p = s->protocol;
339         struct snd_pcm_substream *pcm = READ_ONCE(s->pcm);
340         unsigned int pcm_frames;
341 
342         if (pcm) {
343                 write_pcm_s32(s, pcm, buffer, data_blocks);
344                 pcm_frames = data_blocks * p->frame_multiplier;
345         } else {
346                 write_pcm_silence(s, buffer, data_blocks);
347                 pcm_frames = 0;
348         }
349 
350         if (p->midi_ports)
351                 write_midi_messages(s, buffer, data_blocks);
352 
353         return pcm_frames;
354 }
355 
356 static unsigned int process_tx_data_blocks(struct amdtp_stream *s, __be32 *buffer,
357                                            unsigned int data_blocks, unsigned int *syt)
358 {
359         struct amdtp_am824 *p = s->protocol;
360         struct snd_pcm_substream *pcm = READ_ONCE(s->pcm);
361         unsigned int pcm_frames;
362 
363         if (pcm) {
364                 read_pcm_s32(s, pcm, buffer, data_blocks);
365                 pcm_frames = data_blocks * p->frame_multiplier;
366         } else {
367                 pcm_frames = 0;
368         }
369 
370         if (p->midi_ports)
371                 read_midi_messages(s, buffer, data_blocks);
372 
373         return pcm_frames;
374 }
375 
376 /**
377  * amdtp_am824_init - initialize an AMDTP stream structure to handle AM824
378  *                    data block
379  * @s: the AMDTP stream to initialize
380  * @unit: the target of the stream
381  * @dir: the direction of stream
382  * @flags: the packet transmission method to use
383  */
384 int amdtp_am824_init(struct amdtp_stream *s, struct fw_unit *unit,
385                      enum amdtp_stream_direction dir, enum cip_flags flags)
386 {
387         amdtp_stream_process_data_blocks_t process_data_blocks;
388 
389         if (dir == AMDTP_IN_STREAM)
390                 process_data_blocks = process_tx_data_blocks;
391         else
392                 process_data_blocks = process_rx_data_blocks;
393 
394         return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,
395                                  process_data_blocks,
396                                  sizeof(struct amdtp_am824));
397 }
398 EXPORT_SYMBOL_GPL(amdtp_am824_init);
399 

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