1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * amdtp-dot.c - a part of driver for Digidesign Digi 002/003 family
4  *
5  * Copyright (c) 2014-2015 Takashi Sakamoto
6  * Copyright (C) 2012 Robin Gareus <robin@gareus.org>
7  * Copyright (C) 2012 Damien Zammit <damien@zamaudio.com>
8  */
9 
10 #include <sound/pcm.h>
11 #include "digi00x.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 /* 3 = MAX(DOT_MIDI_IN_PORTS, DOT_MIDI_OUT_PORTS) + 1. */
31 #define MAX_MIDI_PORTS		3
32 
33 /*
34  * The double-oh-three algorithm was discovered by Robin Gareus and Damien
35  * Zammit in 2012, with reverse-engineering for Digi 003 Rack.
36  */
37 struct dot_state {
38 	u8 carry;
39 	u8 idx;
40 	unsigned int off;
41 };
42 
43 struct amdtp_dot {
44 	unsigned int pcm_channels;
45 	struct dot_state state;
46 
47 	struct snd_rawmidi_substream *midi[MAX_MIDI_PORTS];
48 	int midi_fifo_used[MAX_MIDI_PORTS];
49 	int midi_fifo_limit;
50 };
51 
52 /*
53  * double-oh-three look up table
54  *
55  * @param idx index byte (audio-sample data) 0x00..0xff
56  * @param off channel offset shift
57  * @return salt to XOR with given data
58  */
59 #define BYTE_PER_SAMPLE (4)
60 #define MAGIC_DOT_BYTE (2)
61 #define MAGIC_BYTE_OFF(x) (((x) * BYTE_PER_SAMPLE) + MAGIC_DOT_BYTE)
62 static u8 dot_scrt(const u8 idx, const unsigned int off)
63 {
64 	/*
65 	 * the length of the added pattern only depends on the lower nibble
66 	 * of the last non-zero data
67 	 */
68 	static const u8 len[16] = {0, 1, 3, 5, 7, 9, 11, 13, 14,
69 				   12, 10, 8, 6, 4, 2, 0};
70 
71 	/*
72 	 * the lower nibble of the salt. Interleaved sequence.
73 	 * this is walked backwards according to len[]
74 	 */
75 	static const u8 nib[15] = {0x8, 0x7, 0x9, 0x6, 0xa, 0x5, 0xb, 0x4,
76 				   0xc, 0x3, 0xd, 0x2, 0xe, 0x1, 0xf};
77 
78 	/* circular list for the salt's hi nibble. */
79 	static const u8 hir[15] = {0x0, 0x6, 0xf, 0x8, 0x7, 0x5, 0x3, 0x4,
80 				   0xc, 0xd, 0xe, 0x1, 0x2, 0xb, 0xa};
81 
82 	/*
83 	 * start offset for upper nibble mapping.
84 	 * note: 9 is /special/. In the case where the high nibble == 0x9,
85 	 * hir[] is not used and - coincidentally - the salt's hi nibble is
86 	 * 0x09 regardless of the offset.
87 	 */
88 	static const u8 hio[16] = {0, 11, 12, 6, 7, 5, 1, 4,
89 				   3, 0x00, 14, 13, 8, 9, 10, 2};
90 
91 	const u8 ln = idx & 0xf;
92 	const u8 hn = (idx >> 4) & 0xf;
93 	const u8 hr = (hn == 0x9) ? 0x9 : hir[(hio[hn] + off) % 15];
94 
95 	if (len[ln] < off)
96 		return 0x00;
97 
98 	return ((nib[14 + off - len[ln]]) | (hr << 4));
99 }
100 
101 static void dot_encode_step(struct dot_state *state, __be32 *const buffer)
102 {
103 	u8 * const data = (u8 *) buffer;
104 
105 	if (data[MAGIC_DOT_BYTE] != 0x00) {
106 		state->off = 0;
107 		state->idx = data[MAGIC_DOT_BYTE] ^ state->carry;
108 	}
109 	data[MAGIC_DOT_BYTE] ^= state->carry;
110 	state->carry = dot_scrt(state->idx, ++(state->off));
111 }
112 
113 int amdtp_dot_set_parameters(struct amdtp_stream *s, unsigned int rate,
114 			     unsigned int pcm_channels)
115 {
116 	struct amdtp_dot *p = s->protocol;
117 	int err;
118 
119 	if (amdtp_stream_running(s))
120 		return -EBUSY;
121 
122 	/*
123 	 * A first data channel is for MIDI messages, the rest is Multi Bit
124 	 * Linear Audio data channel.
125 	 */
126 	err = amdtp_stream_set_parameters(s, rate, pcm_channels + 1);
127 	if (err < 0)
128 		return err;
129 
130 	s->ctx_data.rx.fdf = AMDTP_FDF_AM824 | s->sfc;
131 
132 	p->pcm_channels = pcm_channels;
133 
134 	/*
135 	 * We do not know the actual MIDI FIFO size of most devices.  Just
136 	 * assume two bytes, i.e., one byte can be received over the bus while
137 	 * the previous one is transmitted over MIDI.
138 	 * (The value here is adjusted for midi_ratelimit_per_packet().)
139 	 */
140 	p->midi_fifo_limit = rate - MIDI_BYTES_PER_SECOND * s->syt_interval + 1;
141 
142 	return 0;
143 }
144 
145 static void write_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
146 			  __be32 *buffer, unsigned int frames,
147 			  unsigned int pcm_frames)
148 {
149 	struct amdtp_dot *p = s->protocol;
150 	unsigned int channels = p->pcm_channels;
151 	struct snd_pcm_runtime *runtime = pcm->runtime;
152 	unsigned int pcm_buffer_pointer;
153 	int remaining_frames;
154 	const u32 *src;
155 	int i, c;
156 
157 	pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;
158 	pcm_buffer_pointer %= runtime->buffer_size;
159 
160 	src = (void *)runtime->dma_area +
161 				frames_to_bytes(runtime, pcm_buffer_pointer);
162 	remaining_frames = runtime->buffer_size - pcm_buffer_pointer;
163 
164 	buffer++;
165 	for (i = 0; i < frames; ++i) {
166 		for (c = 0; c < channels; ++c) {
167 			buffer[c] = cpu_to_be32((*src >> 8) | 0x40000000);
168 			dot_encode_step(&p->state, &buffer[c]);
169 			src++;
170 		}
171 		buffer += s->data_block_quadlets;
172 		if (--remaining_frames == 0)
173 			src = (void *)runtime->dma_area;
174 	}
175 }
176 
177 static void read_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
178 			 __be32 *buffer, unsigned int frames,
179 			 unsigned int pcm_frames)
180 {
181 	struct amdtp_dot *p = s->protocol;
182 	unsigned int channels = p->pcm_channels;
183 	struct snd_pcm_runtime *runtime = pcm->runtime;
184 	unsigned int pcm_buffer_pointer;
185 	int remaining_frames;
186 	u32 *dst;
187 	int i, c;
188 
189 	pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;
190 	pcm_buffer_pointer %= runtime->buffer_size;
191 
192 	dst  = (void *)runtime->dma_area +
193 				frames_to_bytes(runtime, pcm_buffer_pointer);
194 	remaining_frames = runtime->buffer_size - pcm_buffer_pointer;
195 
196 	buffer++;
197 	for (i = 0; i < frames; ++i) {
198 		for (c = 0; c < channels; ++c) {
199 			*dst = be32_to_cpu(buffer[c]) << 8;
200 			dst++;
201 		}
202 		buffer += s->data_block_quadlets;
203 		if (--remaining_frames == 0)
204 			dst = (void *)runtime->dma_area;
205 	}
206 }
207 
208 static void write_pcm_silence(struct amdtp_stream *s, __be32 *buffer,
209 			      unsigned int data_blocks)
210 {
211 	struct amdtp_dot *p = s->protocol;
212 	unsigned int channels, i, c;
213 
214 	channels = p->pcm_channels;
215 
216 	buffer++;
217 	for (i = 0; i < data_blocks; ++i) {
218 		for (c = 0; c < channels; ++c)
219 			buffer[c] = cpu_to_be32(0x40000000);
220 		buffer += s->data_block_quadlets;
221 	}
222 }
223 
224 static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port)
225 {
226 	struct amdtp_dot *p = s->protocol;
227 	int used;
228 
229 	used = p->midi_fifo_used[port];
230 	if (used == 0)
231 		return true;
232 
233 	used -= MIDI_BYTES_PER_SECOND * s->syt_interval;
234 	used = max(used, 0);
235 	p->midi_fifo_used[port] = used;
236 
237 	return used < p->midi_fifo_limit;
238 }
239 
240 static inline void midi_use_bytes(struct amdtp_stream *s,
241 				  unsigned int port, unsigned int count)
242 {
243 	struct amdtp_dot *p = s->protocol;
244 
245 	p->midi_fifo_used[port] += amdtp_rate_table[s->sfc] * count;
246 }
247 
248 static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,
249 		unsigned int data_blocks, unsigned int data_block_counter)
250 {
251 	struct amdtp_dot *p = s->protocol;
252 	unsigned int f, port;
253 	int len;
254 	u8 *b;
255 
256 	for (f = 0; f < data_blocks; f++) {
257 		port = (data_block_counter + f) % 8;
258 		b = (u8 *)&buffer[0];
259 
260 		len = 0;
261 		if (port < MAX_MIDI_PORTS &&
262 		    midi_ratelimit_per_packet(s, port) &&
263 		    p->midi[port] != NULL)
264 			len = snd_rawmidi_transmit(p->midi[port], b + 1, 2);
265 
266 		if (len > 0) {
267 			/*
268 			 * Upper 4 bits of LSB represent port number.
269 			 * - 0000b: physical MIDI port 1.
270 			 * - 0010b: physical MIDI port 2.
271 			 * - 1110b: console MIDI port.
272 			 */
273 			if (port == 2)
274 				b[3] = 0xe0;
275 			else if (port == 1)
276 				b[3] = 0x20;
277 			else
278 				b[3] = 0x00;
279 			b[3] |= len;
280 			midi_use_bytes(s, port, len);
281 		} else {
282 			b[1] = 0;
283 			b[2] = 0;
284 			b[3] = 0;
285 		}
286 		b[0] = 0x80;
287 
288 		buffer += s->data_block_quadlets;
289 	}
290 }
291 
292 static void read_midi_messages(struct amdtp_stream *s, __be32 *buffer,
293 			       unsigned int data_blocks)
294 {
295 	struct amdtp_dot *p = s->protocol;
296 	unsigned int f, port, len;
297 	u8 *b;
298 
299 	for (f = 0; f < data_blocks; f++) {
300 		b = (u8 *)&buffer[0];
301 
302 		len = b[3] & 0x0f;
303 		if (len > 0) {
304 			/*
305 			 * Upper 4 bits of LSB represent port number.
306 			 * - 0000b: physical MIDI port 1. Use port 0.
307 			 * - 1110b: console MIDI port. Use port 2.
308 			 */
309 			if (b[3] >> 4 > 0)
310 				port = 2;
311 			else
312 				port = 0;
313 
314 			if (port < MAX_MIDI_PORTS && p->midi[port])
315 				snd_rawmidi_receive(p->midi[port], b + 1, len);
316 		}
317 
318 		buffer += s->data_block_quadlets;
319 	}
320 }
321 
322 int amdtp_dot_add_pcm_hw_constraints(struct amdtp_stream *s,
323 				     struct snd_pcm_runtime *runtime)
324 {
325 	int err;
326 
327 	/* This protocol delivers 24 bit data in 32bit data channel. */
328 	err = snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
329 	if (err < 0)
330 		return err;
331 
332 	return amdtp_stream_add_pcm_hw_constraints(s, runtime);
333 }
334 
335 void amdtp_dot_midi_trigger(struct amdtp_stream *s, unsigned int port,
336 			  struct snd_rawmidi_substream *midi)
337 {
338 	struct amdtp_dot *p = s->protocol;
339 
340 	if (port < MAX_MIDI_PORTS)
341 		WRITE_ONCE(p->midi[port], midi);
342 }
343 
344 static unsigned int process_ir_ctx_payloads(struct amdtp_stream *s,
345 					    const struct pkt_desc *descs,
346 					    unsigned int packets,
347 					    struct snd_pcm_substream *pcm)
348 {
349 	unsigned int pcm_frames = 0;
350 	int i;
351 
352 	for (i = 0; i < packets; ++i) {
353 		const struct pkt_desc *desc = descs + i;
354 		__be32 *buf = desc->ctx_payload;
355 		unsigned int data_blocks = desc->data_blocks;
356 
357 		if (pcm) {
358 			read_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);
359 			pcm_frames += data_blocks;
360 		}
361 
362 		read_midi_messages(s, buf, data_blocks);
363 	}
364 
365 	return pcm_frames;
366 }
367 
368 static unsigned int process_it_ctx_payloads(struct amdtp_stream *s,
369 					    const struct pkt_desc *descs,
370 					    unsigned int packets,
371 					    struct snd_pcm_substream *pcm)
372 {
373 	unsigned int pcm_frames = 0;
374 	int i;
375 
376 	for (i = 0; i < packets; ++i) {
377 		const struct pkt_desc *desc = descs + i;
378 		__be32 *buf = desc->ctx_payload;
379 		unsigned int data_blocks = desc->data_blocks;
380 
381 		if (pcm) {
382 			write_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);
383 			pcm_frames += data_blocks;
384 		} else {
385 			write_pcm_silence(s, buf, data_blocks);
386 		}
387 
388 		write_midi_messages(s, buf, data_blocks,
389 				    desc->data_block_counter);
390 	}
391 
392 	return pcm_frames;
393 }
394 
395 int amdtp_dot_init(struct amdtp_stream *s, struct fw_unit *unit,
396 		 enum amdtp_stream_direction dir)
397 {
398 	amdtp_stream_process_ctx_payloads_t process_ctx_payloads;
399 	enum cip_flags flags;
400 
401 	// Use different mode between incoming/outgoing.
402 	if (dir == AMDTP_IN_STREAM) {
403 		flags = CIP_NONBLOCKING;
404 		process_ctx_payloads = process_ir_ctx_payloads;
405 	} else {
406 		flags = CIP_BLOCKING;
407 		process_ctx_payloads = process_it_ctx_payloads;
408 	}
409 
410 	return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,
411 				process_ctx_payloads, sizeof(struct amdtp_dot));
412 }
413 
414 void amdtp_dot_reset(struct amdtp_stream *s)
415 {
416 	struct amdtp_dot *p = s->protocol;
417 
418 	p->state.carry = 0x00;
419 	p->state.idx = 0x00;
420 	p->state.off = 0;
421 }
422