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Linux/sound/firewire/digi00x/amdtp-dot.c

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  1 /*
  2  * amdtp-dot.c - a part of driver for Digidesign Digi 002/003 family
  3  *
  4  * Copyright (c) 2014-2015 Takashi Sakamoto
  5  * Copyright (C) 2012 Robin Gareus <robin@gareus.org>
  6  * Copyright (C) 2012 Damien Zammit <damien@zamaudio.com>
  7  *
  8  * Licensed under the terms of the GNU General Public License, version 2.
  9  */
 10 
 11 #include <sound/pcm.h>
 12 #include "digi00x.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 /* 3 = MAX(DOT_MIDI_IN_PORTS, DOT_MIDI_OUT_PORTS) + 1. */
 32 #define MAX_MIDI_PORTS          3
 33 
 34 /*
 35  * The double-oh-three algorithm was discovered by Robin Gareus and Damien
 36  * Zammit in 2012, with reverse-engineering for Digi 003 Rack.
 37  */
 38 struct dot_state {
 39         u8 carry;
 40         u8 idx;
 41         unsigned int off;
 42 };
 43 
 44 struct amdtp_dot {
 45         unsigned int pcm_channels;
 46         struct dot_state state;
 47 
 48         struct snd_rawmidi_substream *midi[MAX_MIDI_PORTS];
 49         int midi_fifo_used[MAX_MIDI_PORTS];
 50         int midi_fifo_limit;
 51 };
 52 
 53 /*
 54  * double-oh-three look up table
 55  *
 56  * @param idx index byte (audio-sample data) 0x00..0xff
 57  * @param off channel offset shift
 58  * @return salt to XOR with given data
 59  */
 60 #define BYTE_PER_SAMPLE (4)
 61 #define MAGIC_DOT_BYTE (2)
 62 #define MAGIC_BYTE_OFF(x) (((x) * BYTE_PER_SAMPLE) + MAGIC_DOT_BYTE)
 63 static u8 dot_scrt(const u8 idx, const unsigned int off)
 64 {
 65         /*
 66          * the length of the added pattern only depends on the lower nibble
 67          * of the last non-zero data
 68          */
 69         static const u8 len[16] = {0, 1, 3, 5, 7, 9, 11, 13, 14,
 70                                    12, 10, 8, 6, 4, 2, 0};
 71 
 72         /*
 73          * the lower nibble of the salt. Interleaved sequence.
 74          * this is walked backwards according to len[]
 75          */
 76         static const u8 nib[15] = {0x8, 0x7, 0x9, 0x6, 0xa, 0x5, 0xb, 0x4,
 77                                    0xc, 0x3, 0xd, 0x2, 0xe, 0x1, 0xf};
 78 
 79         /* circular list for the salt's hi nibble. */
 80         static const u8 hir[15] = {0x0, 0x6, 0xf, 0x8, 0x7, 0x5, 0x3, 0x4,
 81                                    0xc, 0xd, 0xe, 0x1, 0x2, 0xb, 0xa};
 82 
 83         /*
 84          * start offset for upper nibble mapping.
 85          * note: 9 is /special/. In the case where the high nibble == 0x9,
 86          * hir[] is not used and - coincidentally - the salt's hi nibble is
 87          * 0x09 regardless of the offset.
 88          */
 89         static const u8 hio[16] = {0, 11, 12, 6, 7, 5, 1, 4,
 90                                    3, 0x00, 14, 13, 8, 9, 10, 2};
 91 
 92         const u8 ln = idx & 0xf;
 93         const u8 hn = (idx >> 4) & 0xf;
 94         const u8 hr = (hn == 0x9) ? 0x9 : hir[(hio[hn] + off) % 15];
 95 
 96         if (len[ln] < off)
 97                 return 0x00;
 98 
 99         return ((nib[14 + off - len[ln]]) | (hr << 4));
100 }
101 
102 static void dot_encode_step(struct dot_state *state, __be32 *const buffer)
103 {
104         u8 * const data = (u8 *) buffer;
105 
106         if (data[MAGIC_DOT_BYTE] != 0x00) {
107                 state->off = 0;
108                 state->idx = data[MAGIC_DOT_BYTE] ^ state->carry;
109         }
110         data[MAGIC_DOT_BYTE] ^= state->carry;
111         state->carry = dot_scrt(state->idx, ++(state->off));
112 }
113 
114 int amdtp_dot_set_parameters(struct amdtp_stream *s, unsigned int rate,
115                              unsigned int pcm_channels)
116 {
117         struct amdtp_dot *p = s->protocol;
118         int err;
119 
120         if (amdtp_stream_running(s))
121                 return -EBUSY;
122 
123         /*
124          * A first data channel is for MIDI messages, the rest is Multi Bit
125          * Linear Audio data channel.
126          */
127         err = amdtp_stream_set_parameters(s, rate, pcm_channels + 1);
128         if (err < 0)
129                 return err;
130 
131         s->fdf = AMDTP_FDF_AM824 | s->sfc;
132 
133         p->pcm_channels = pcm_channels;
134 
135         /*
136          * We do not know the actual MIDI FIFO size of most devices.  Just
137          * assume two bytes, i.e., one byte can be received over the bus while
138          * the previous one is transmitted over MIDI.
139          * (The value here is adjusted for midi_ratelimit_per_packet().)
140          */
141         p->midi_fifo_limit = rate - MIDI_BYTES_PER_SECOND * s->syt_interval + 1;
142 
143         return 0;
144 }
145 
146 static void write_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
147                           __be32 *buffer, unsigned int frames)
148 {
149         struct amdtp_dot *p = s->protocol;
150         struct snd_pcm_runtime *runtime = pcm->runtime;
151         unsigned int channels, remaining_frames, i, c;
152         const u32 *src;
153 
154         channels = p->pcm_channels;
155         src = (void *)runtime->dma_area +
156                         frames_to_bytes(runtime, s->pcm_buffer_pointer);
157         remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
158 
159         buffer++;
160         for (i = 0; i < frames; ++i) {
161                 for (c = 0; c < channels; ++c) {
162                         buffer[c] = cpu_to_be32((*src >> 8) | 0x40000000);
163                         dot_encode_step(&p->state, &buffer[c]);
164                         src++;
165                 }
166                 buffer += s->data_block_quadlets;
167                 if (--remaining_frames == 0)
168                         src = (void *)runtime->dma_area;
169         }
170 }
171 
172 static void read_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
173                          __be32 *buffer, unsigned int frames)
174 {
175         struct amdtp_dot *p = s->protocol;
176         struct snd_pcm_runtime *runtime = pcm->runtime;
177         unsigned int channels, remaining_frames, i, c;
178         u32 *dst;
179 
180         channels = p->pcm_channels;
181         dst  = (void *)runtime->dma_area +
182                         frames_to_bytes(runtime, s->pcm_buffer_pointer);
183         remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
184 
185         buffer++;
186         for (i = 0; i < frames; ++i) {
187                 for (c = 0; c < channels; ++c) {
188                         *dst = be32_to_cpu(buffer[c]) << 8;
189                         dst++;
190                 }
191                 buffer += s->data_block_quadlets;
192                 if (--remaining_frames == 0)
193                         dst = (void *)runtime->dma_area;
194         }
195 }
196 
197 static void write_pcm_silence(struct amdtp_stream *s, __be32 *buffer,
198                               unsigned int data_blocks)
199 {
200         struct amdtp_dot *p = s->protocol;
201         unsigned int channels, i, c;
202 
203         channels = p->pcm_channels;
204 
205         buffer++;
206         for (i = 0; i < data_blocks; ++i) {
207                 for (c = 0; c < channels; ++c)
208                         buffer[c] = cpu_to_be32(0x40000000);
209                 buffer += s->data_block_quadlets;
210         }
211 }
212 
213 static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port)
214 {
215         struct amdtp_dot *p = s->protocol;
216         int used;
217 
218         used = p->midi_fifo_used[port];
219         if (used == 0)
220                 return true;
221 
222         used -= MIDI_BYTES_PER_SECOND * s->syt_interval;
223         used = max(used, 0);
224         p->midi_fifo_used[port] = used;
225 
226         return used < p->midi_fifo_limit;
227 }
228 
229 static inline void midi_use_bytes(struct amdtp_stream *s,
230                                   unsigned int port, unsigned int count)
231 {
232         struct amdtp_dot *p = s->protocol;
233 
234         p->midi_fifo_used[port] += amdtp_rate_table[s->sfc] * count;
235 }
236 
237 static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,
238                                 unsigned int data_blocks)
239 {
240         struct amdtp_dot *p = s->protocol;
241         unsigned int f, port;
242         int len;
243         u8 *b;
244 
245         for (f = 0; f < data_blocks; f++) {
246                 port = (s->data_block_counter + f) % 8;
247                 b = (u8 *)&buffer[0];
248 
249                 len = 0;
250                 if (port < MAX_MIDI_PORTS &&
251                     midi_ratelimit_per_packet(s, port) &&
252                     p->midi[port] != NULL)
253                         len = snd_rawmidi_transmit(p->midi[port], b + 1, 2);
254 
255                 if (len > 0) {
256                         /*
257                          * Upper 4 bits of LSB represent port number.
258                          * - 0000b: physical MIDI port 1.
259                          * - 0010b: physical MIDI port 2.
260                          * - 1110b: console MIDI port.
261                          */
262                         if (port == 2)
263                                 b[3] = 0xe0;
264                         else if (port == 1)
265                                 b[3] = 0x20;
266                         else
267                                 b[3] = 0x00;
268                         b[3] |= len;
269                         midi_use_bytes(s, port, len);
270                 } else {
271                         b[1] = 0;
272                         b[2] = 0;
273                         b[3] = 0;
274                 }
275                 b[0] = 0x80;
276 
277                 buffer += s->data_block_quadlets;
278         }
279 }
280 
281 static void read_midi_messages(struct amdtp_stream *s, __be32 *buffer,
282                                unsigned int data_blocks)
283 {
284         struct amdtp_dot *p = s->protocol;
285         unsigned int f, port, len;
286         u8 *b;
287 
288         for (f = 0; f < data_blocks; f++) {
289                 b = (u8 *)&buffer[0];
290 
291                 len = b[3] & 0x0f;
292                 if (len > 0) {
293                         /*
294                          * Upper 4 bits of LSB represent port number.
295                          * - 0000b: physical MIDI port 1. Use port 0.
296                          * - 1110b: console MIDI port. Use port 2.
297                          */
298                         if (b[3] >> 4 > 0)
299                                 port = 2;
300                         else
301                                 port = 0;
302 
303                         if (port < MAX_MIDI_PORTS && p->midi[port])
304                                 snd_rawmidi_receive(p->midi[port], b + 1, len);
305                 }
306 
307                 buffer += s->data_block_quadlets;
308         }
309 }
310 
311 int amdtp_dot_add_pcm_hw_constraints(struct amdtp_stream *s,
312                                      struct snd_pcm_runtime *runtime)
313 {
314         int err;
315 
316         /* This protocol delivers 24 bit data in 32bit data channel. */
317         err = snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
318         if (err < 0)
319                 return err;
320 
321         return amdtp_stream_add_pcm_hw_constraints(s, runtime);
322 }
323 
324 void amdtp_dot_midi_trigger(struct amdtp_stream *s, unsigned int port,
325                           struct snd_rawmidi_substream *midi)
326 {
327         struct amdtp_dot *p = s->protocol;
328 
329         if (port < MAX_MIDI_PORTS)
330                 ACCESS_ONCE(p->midi[port]) = midi;
331 }
332 
333 static unsigned int process_tx_data_blocks(struct amdtp_stream *s,
334                                            __be32 *buffer,
335                                            unsigned int data_blocks,
336                                            unsigned int *syt)
337 {
338         struct snd_pcm_substream *pcm;
339         unsigned int pcm_frames;
340 
341         pcm = ACCESS_ONCE(s->pcm);
342         if (pcm) {
343                 read_pcm_s32(s, pcm, buffer, data_blocks);
344                 pcm_frames = data_blocks;
345         } else {
346                 pcm_frames = 0;
347         }
348 
349         read_midi_messages(s, buffer, data_blocks);
350 
351         return pcm_frames;
352 }
353 
354 static unsigned int process_rx_data_blocks(struct amdtp_stream *s,
355                                            __be32 *buffer,
356                                            unsigned int data_blocks,
357                                            unsigned int *syt)
358 {
359         struct snd_pcm_substream *pcm;
360         unsigned int pcm_frames;
361 
362         pcm = ACCESS_ONCE(s->pcm);
363         if (pcm) {
364                 write_pcm_s32(s, pcm, buffer, data_blocks);
365                 pcm_frames = data_blocks;
366         } else {
367                 write_pcm_silence(s, buffer, data_blocks);
368                 pcm_frames = 0;
369         }
370 
371         write_midi_messages(s, buffer, data_blocks);
372 
373         return pcm_frames;
374 }
375 
376 int amdtp_dot_init(struct amdtp_stream *s, struct fw_unit *unit,
377                  enum amdtp_stream_direction dir)
378 {
379         amdtp_stream_process_data_blocks_t process_data_blocks;
380         enum cip_flags flags;
381 
382         /* Use different mode between incoming/outgoing. */
383         if (dir == AMDTP_IN_STREAM) {
384                 flags = CIP_NONBLOCKING;
385                 process_data_blocks = process_tx_data_blocks;
386         } else {
387                 flags = CIP_BLOCKING;
388                 process_data_blocks = process_rx_data_blocks;
389         }
390 
391         return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,
392                                  process_data_blocks, sizeof(struct amdtp_dot));
393 }
394 
395 void amdtp_dot_reset(struct amdtp_stream *s)
396 {
397         struct amdtp_dot *p = s->protocol;
398 
399         p->state.carry = 0x00;
400         p->state.idx = 0x00;
401         p->state.off = 0;
402 }
403 

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