firewire/digi00x/amdtp-dot.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * amdtp-dot.c - a part of driver for Digidesign Digi 002/003 family
0004  *
0005  * Copyright (c) 2014-2015 Takashi Sakamoto
0006  * Copyright (C) 2012 Robin Gareus <robin@gareus.org>
0007  * Copyright (C) 2012 Damien Zammit <damien@zamaudio.com>
0008  */
0009
0010 #include <sound/pcm.h>
0011 #include "digi00x.h"
0012
0013 #define CIP_FMT_AM      0x10
0014
0015 /* 'Clock-based rate control mode' is just supported. */
0016 #define AMDTP_FDF_AM824     0x00
0017
0018 /*
0019  * Nominally 3125 bytes/second, but the MIDI port's clock might be
0020  * 1% too slow, and the bus clock 100 ppm too fast.
0021  */
0022 #define MIDI_BYTES_PER_SECOND   3093
0023
0024 /*
0025  * Several devices look only at the first eight data blocks.
0026  * In any case, this is more than enough for the MIDI data rate.
0027  */
0028 #define MAX_MIDI_RX_BLOCKS  8
0029
0030 /* 3 = MAX(DOT_MIDI_IN_PORTS, DOT_MIDI_OUT_PORTS) + 1. */
0031 #define MAX_MIDI_PORTS      3
0032
0033 /*
0034  * The double-oh-three algorithm was discovered by Robin Gareus and Damien
0035  * Zammit in 2012, with reverse-engineering for Digi 003 Rack.
0036  */
0037 struct dot_state {
0038     u8 carry;
0039     u8 idx;
0040     unsigned int off;
0041 };
0042
0043 struct amdtp_dot {
0044     unsigned int pcm_channels;
0045     struct dot_state state;
0046
0047     struct snd_rawmidi_substream *midi[MAX_MIDI_PORTS];
0048     int midi_fifo_used[MAX_MIDI_PORTS];
0049     int midi_fifo_limit;
0050 };
0051
0052 /*
0053  * double-oh-three look up table
0054  *
0055  * @param idx index byte (audio-sample data) 0x00..0xff
0056  * @param off channel offset shift
0057  * @return salt to XOR with given data
0058  */
0059 #define BYTE_PER_SAMPLE (4)
0060 #define MAGIC_DOT_BYTE (2)
0061 #define MAGIC_BYTE_OFF(x) (((x) * BYTE_PER_SAMPLE) + MAGIC_DOT_BYTE)
0062 static u8 dot_scrt(const u8 idx, const unsigned int off)
0063 {
0064     /*
0065      * the length of the added pattern only depends on the lower nibble
0066      * of the last non-zero data
0067      */
0068     static const u8 len[16] = {0, 1, 3, 5, 7, 9, 11, 13, 14,
0069                    12, 10, 8, 6, 4, 2, 0};
0070
0071     /*
0072      * the lower nibble of the salt. Interleaved sequence.
0073      * this is walked backwards according to len[]
0074      */
0075     static const u8 nib[15] = {0x8, 0x7, 0x9, 0x6, 0xa, 0x5, 0xb, 0x4,
0076                    0xc, 0x3, 0xd, 0x2, 0xe, 0x1, 0xf};
0077
0078     /* circular list for the salt's hi nibble. */
0079     static const u8 hir[15] = {0x0, 0x6, 0xf, 0x8, 0x7, 0x5, 0x3, 0x4,
0080                    0xc, 0xd, 0xe, 0x1, 0x2, 0xb, 0xa};
0081
0082     /*
0083      * start offset for upper nibble mapping.
0084      * note: 9 is /special/. In the case where the high nibble == 0x9,
0085      * hir[] is not used and - coincidentally - the salt's hi nibble is
0086      * 0x09 regardless of the offset.
0087      */
0088     static const u8 hio[16] = {0, 11, 12, 6, 7, 5, 1, 4,
0089                    3, 0x00, 14, 13, 8, 9, 10, 2};
0090
0091     const u8 ln = idx & 0xf;
0092     const u8 hn = (idx >> 4) & 0xf;
0093     const u8 hr = (hn == 0x9) ? 0x9 : hir[(hio[hn] + off) % 15];
0094
0095     if (len[ln] < off)
0096         return 0x00;
0097
0098     return ((nib[14 + off - len[ln]]) | (hr << 4));
0099 }
0100
0101 static void dot_encode_step(struct dot_state *state, __be32 *const buffer)
0102 {
0103     u8 * const data = (u8 *) buffer;
0104
0105     if (data[MAGIC_DOT_BYTE] != 0x00) {
0106         state->off = 0;
0107         state->idx = data[MAGIC_DOT_BYTE] ^ state->carry;
0108     }
0109     data[MAGIC_DOT_BYTE] ^= state->carry;
0110     state->carry = dot_scrt(state->idx, ++(state->off));
0111 }
0112
0113 int amdtp_dot_set_parameters(struct amdtp_stream *s, unsigned int rate,
0114                  unsigned int pcm_channels)
0115 {
0116     struct amdtp_dot *p = s->protocol;
0117     int err;
0118
0119     if (amdtp_stream_running(s))
0120         return -EBUSY;
0121
0122     /*
0123      * A first data channel is for MIDI messages, the rest is Multi Bit
0124      * Linear Audio data channel.
0125      */
0126     err = amdtp_stream_set_parameters(s, rate, pcm_channels + 1);
0127     if (err < 0)
0128         return err;
0129
0130     s->ctx_data.rx.fdf = AMDTP_FDF_AM824 | s->sfc;
0131
0132     p->pcm_channels = pcm_channels;
0133
0134     /*
0135      * We do not know the actual MIDI FIFO size of most devices.  Just
0136      * assume two bytes, i.e., one byte can be received over the bus while
0137      * the previous one is transmitted over MIDI.
0138      * (The value here is adjusted for midi_ratelimit_per_packet().)
0139      */
0140     p->midi_fifo_limit = rate - MIDI_BYTES_PER_SECOND * s->syt_interval + 1;
0141
0142     return 0;
0143 }
0144
0145 static void write_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
0146               __be32 *buffer, unsigned int frames,
0147               unsigned int pcm_frames)
0148 {
0149     struct amdtp_dot *p = s->protocol;
0150     unsigned int channels = p->pcm_channels;
0151     struct snd_pcm_runtime *runtime = pcm->runtime;
0152     unsigned int pcm_buffer_pointer;
0153     int remaining_frames;
0154     const u32 *src;
0155     int i, c;
0156
0157     pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;
0158     pcm_buffer_pointer %= runtime->buffer_size;
0159
0160     src = (void *)runtime->dma_area +
0161                 frames_to_bytes(runtime, pcm_buffer_pointer);
0162     remaining_frames = runtime->buffer_size - pcm_buffer_pointer;
0163
0164     buffer++;
0165     for (i = 0; i < frames; ++i) {
0166         for (c = 0; c < channels; ++c) {
0167             buffer[c] = cpu_to_be32((*src >> 8) | 0x40000000);
0168             dot_encode_step(&p->state, &buffer[c]);
0169             src++;
0170         }
0171         buffer += s->data_block_quadlets;
0172         if (--remaining_frames == 0)
0173             src = (void *)runtime->dma_area;
0174     }
0175 }
0176
0177 static void read_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
0178              __be32 *buffer, unsigned int frames,
0179              unsigned int pcm_frames)
0180 {
0181     struct amdtp_dot *p = s->protocol;
0182     unsigned int channels = p->pcm_channels;
0183     struct snd_pcm_runtime *runtime = pcm->runtime;
0184     unsigned int pcm_buffer_pointer;
0185     int remaining_frames;
0186     u32 *dst;
0187     int i, c;
0188
0189     pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;
0190     pcm_buffer_pointer %= runtime->buffer_size;
0191
0192     dst  = (void *)runtime->dma_area +
0193                 frames_to_bytes(runtime, pcm_buffer_pointer);
0194     remaining_frames = runtime->buffer_size - pcm_buffer_pointer;
0195
0196     buffer++;
0197     for (i = 0; i < frames; ++i) {
0198         for (c = 0; c < channels; ++c) {
0199             *dst = be32_to_cpu(buffer[c]) << 8;
0200             dst++;
0201         }
0202         buffer += s->data_block_quadlets;
0203         if (--remaining_frames == 0)
0204             dst = (void *)runtime->dma_area;
0205     }
0206 }
0207
0208 static void write_pcm_silence(struct amdtp_stream *s, __be32 *buffer,
0209                   unsigned int data_blocks)
0210 {
0211     struct amdtp_dot *p = s->protocol;
0212     unsigned int channels, i, c;
0213
0214     channels = p->pcm_channels;
0215
0216     buffer++;
0217     for (i = 0; i < data_blocks; ++i) {
0218         for (c = 0; c < channels; ++c)
0219             buffer[c] = cpu_to_be32(0x40000000);
0220         buffer += s->data_block_quadlets;
0221     }
0222 }
0223
0224 static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port)
0225 {
0226     struct amdtp_dot *p = s->protocol;
0227     int used;
0228
0229     used = p->midi_fifo_used[port];
0230     if (used == 0)
0231         return true;
0232
0233     used -= MIDI_BYTES_PER_SECOND * s->syt_interval;
0234     used = max(used, 0);
0235     p->midi_fifo_used[port] = used;
0236
0237     return used < p->midi_fifo_limit;
0238 }
0239
0240 static inline void midi_use_bytes(struct amdtp_stream *s,
0241                   unsigned int port, unsigned int count)
0242 {
0243     struct amdtp_dot *p = s->protocol;
0244
0245     p->midi_fifo_used[port] += amdtp_rate_table[s->sfc] * count;
0246 }
0247
0248 static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,
0249         unsigned int data_blocks, unsigned int data_block_counter)
0250 {
0251     struct amdtp_dot *p = s->protocol;
0252     unsigned int f, port;
0253     int len;
0254     u8 *b;
0255
0256     for (f = 0; f < data_blocks; f++) {
0257         port = (data_block_counter + f) % 8;
0258         b = (u8 *)&buffer[0];
0259
0260         len = 0;
0261         if (port < MAX_MIDI_PORTS &&
0262             midi_ratelimit_per_packet(s, port) &&
0263             p->midi[port] != NULL)
0264             len = snd_rawmidi_transmit(p->midi[port], b + 1, 2);
0265
0266         if (len > 0) {
0267             /*
0268              * Upper 4 bits of LSB represent port number.
0269              * - 0000b: physical MIDI port 1.
0270              * - 0010b: physical MIDI port 2.
0271              * - 1110b: console MIDI port.
0272              */
0273             if (port == 2)
0274                 b[3] = 0xe0;
0275             else if (port == 1)
0276                 b[3] = 0x20;
0277             else
0278                 b[3] = 0x00;
0279             b[3] |= len;
0280             midi_use_bytes(s, port, len);
0281         } else {
0282             b[1] = 0;
0283             b[2] = 0;
0284             b[3] = 0;
0285         }
0286         b[0] = 0x80;
0287
0288         buffer += s->data_block_quadlets;
0289     }
0290 }
0291
0292 static void read_midi_messages(struct amdtp_stream *s, __be32 *buffer,
0293                    unsigned int data_blocks)
0294 {
0295     struct amdtp_dot *p = s->protocol;
0296     unsigned int f, port, len;
0297     u8 *b;
0298
0299     for (f = 0; f < data_blocks; f++) {
0300         b = (u8 *)&buffer[0];
0301
0302         len = b[3] & 0x0f;
0303         if (len > 0) {
0304             /*
0305              * Upper 4 bits of LSB represent port number.
0306              * - 0000b: physical MIDI port 1. Use port 0.
0307              * - 1110b: console MIDI port. Use port 2.
0308              */
0309             if (b[3] >> 4 > 0)
0310                 port = 2;
0311             else
0312                 port = 0;
0313
0314             if (port < MAX_MIDI_PORTS && p->midi[port])
0315                 snd_rawmidi_receive(p->midi[port], b + 1, len);
0316         }
0317
0318         buffer += s->data_block_quadlets;
0319     }
0320 }
0321
0322 int amdtp_dot_add_pcm_hw_constraints(struct amdtp_stream *s,
0323                      struct snd_pcm_runtime *runtime)
0324 {
0325     int err;
0326
0327     /* This protocol delivers 24 bit data in 32bit data channel. */
0328     err = snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
0329     if (err < 0)
0330         return err;
0331
0332     return amdtp_stream_add_pcm_hw_constraints(s, runtime);
0333 }
0334
0335 void amdtp_dot_midi_trigger(struct amdtp_stream *s, unsigned int port,
0336               struct snd_rawmidi_substream *midi)
0337 {
0338     struct amdtp_dot *p = s->protocol;
0339
0340     if (port < MAX_MIDI_PORTS)
0341         WRITE_ONCE(p->midi[port], midi);
0342 }
0343
0344 static unsigned int process_ir_ctx_payloads(struct amdtp_stream *s,
0345                         const struct pkt_desc *descs,
0346                         unsigned int packets,
0347                         struct snd_pcm_substream *pcm)
0348 {
0349     unsigned int pcm_frames = 0;
0350     int i;
0351
0352     for (i = 0; i < packets; ++i) {
0353         const struct pkt_desc *desc = descs + i;
0354         __be32 *buf = desc->ctx_payload;
0355         unsigned int data_blocks = desc->data_blocks;
0356
0357         if (pcm) {
0358             read_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);
0359             pcm_frames += data_blocks;
0360         }
0361
0362         read_midi_messages(s, buf, data_blocks);
0363     }
0364
0365     return pcm_frames;
0366 }
0367
0368 static unsigned int process_it_ctx_payloads(struct amdtp_stream *s,
0369                         const struct pkt_desc *descs,
0370                         unsigned int packets,
0371                         struct snd_pcm_substream *pcm)
0372 {
0373     unsigned int pcm_frames = 0;
0374     int i;
0375
0376     for (i = 0; i < packets; ++i) {
0377         const struct pkt_desc *desc = descs + i;
0378         __be32 *buf = desc->ctx_payload;
0379         unsigned int data_blocks = desc->data_blocks;
0380
0381         if (pcm) {
0382             write_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);
0383             pcm_frames += data_blocks;
0384         } else {
0385             write_pcm_silence(s, buf, data_blocks);
0386         }
0387
0388         write_midi_messages(s, buf, data_blocks,
0389                     desc->data_block_counter);
0390     }
0391
0392     return pcm_frames;
0393 }
0394
0395 int amdtp_dot_init(struct amdtp_stream *s, struct fw_unit *unit,
0396          enum amdtp_stream_direction dir)
0397 {
0398     amdtp_stream_process_ctx_payloads_t process_ctx_payloads;
0399     unsigned int flags = CIP_NONBLOCKING | CIP_UNAWARE_SYT;
0400
0401     // Use different mode between incoming/outgoing.
0402     if (dir == AMDTP_IN_STREAM)
0403         process_ctx_payloads = process_ir_ctx_payloads;
0404     else
0405         process_ctx_payloads = process_it_ctx_payloads;
0406
0407     return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,
0408                 process_ctx_payloads, sizeof(struct amdtp_dot));
0409 }
0410
0411 void amdtp_dot_reset(struct amdtp_stream *s)
0412 {
0413     struct amdtp_dot *p = s->protocol;
0414
0415     p->state.carry = 0x00;
0416     p->state.idx = 0x00;
0417     p->state.off = 0;
0418 }