ALSA: firewire-lib: complete AM824 data block processing layer

This commit moves the codes related to data block processing from packet
streaming layer to AM824 layer.

Each driver initializes amdtp stream structure for AM824 data block by
calling amdtp_am824_init(). Then, a memory block is allocated for AM824
specific structure. This memory block is released by calling
amdtp_stream_destroy().

When setting streaming parameters, it calls amdtp_am824_set_parameters().
When starting packet streaming, it calls amdtp_stream_start(). When
stopping packet streaming, it calls amdtp_stream_stop().

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 340 insertions, 9 deletions

diff --git a/sound/firewire/amdtp-am824.c b/sound/firewire/amdtp-am824.c
index 540a101661e2..fe4b83f65831 100644
--- a/sound/firewire/amdtp-am824.c
+++ b/sound/firewire/amdtp-am824.c
@@ -1,11 +1,14 @@
 /*
  * AM824 format in Audio and Music Data Transmission Protocol (IEC 61883-6)
  *
+ * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
  * Copyright (c) 2015 Takashi Sakamoto <o-takashi@sakamocchi.jp>
  *
  * Licensed under the terms of the GNU General Public License, version 2.
  */
 
+#include <linux/slab.h>
+
 #include "amdtp-am824.h"
 
 #define CIP_FMT_AM		0x10
@@ -13,6 +16,35 @@
 /* "Clock-based rate control mode" is just supported. */
 #define AMDTP_FDF_AM824		0x00
 
+/*
+ * Nominally 3125 bytes/second, but the MIDI port's clock might be
+ * 1% too slow, and the bus clock 100 ppm too fast.
+ */
+#define MIDI_BYTES_PER_SECOND	3093
+
+/*
+ * Several devices look only at the first eight data blocks.
+ * In any case, this is more than enough for the MIDI data rate.
+ */
+#define MAX_MIDI_RX_BLOCKS	8
+
+struct amdtp_am824 {
+	struct snd_rawmidi_substream *midi[AM824_MAX_CHANNELS_FOR_MIDI * 8];
+	int midi_fifo_limit;
+	int midi_fifo_used[AM824_MAX_CHANNELS_FOR_MIDI * 8];
+	unsigned int pcm_channels;
+	unsigned int midi_ports;
+
+	u8 pcm_positions[AM824_MAX_CHANNELS_FOR_PCM];
+	u8 midi_position;
+
+	void (*transfer_samples)(struct amdtp_stream *s,
+				 struct snd_pcm_substream *pcm,
+				 __be32 *buffer, unsigned int frames);
+
+	unsigned int frame_multiplier;
+};
+
 /**
  * amdtp_am824_set_parameters - set stream parameters
  * @s: the AMDTP stream to configure
@@ -30,23 +62,58 @@ int amdtp_am824_set_parameters(struct amdtp_stream *s, unsigned int rate,
 			       unsigned int midi_ports,
 			       bool double_pcm_frames)
 {
+	struct amdtp_am824 *p = s->protocol;
+	unsigned int midi_channels;
+	unsigned int i;
 	int err;
 
-	err = amdtp_stream_set_parameters(s, rate, pcm_channels, midi_ports);
+	if (amdtp_stream_running(s))
+		return -EINVAL;
+
+	if (pcm_channels > AM824_MAX_CHANNELS_FOR_PCM)
+		return -EINVAL;
+
+	midi_channels = DIV_ROUND_UP(midi_ports, 8);
+	if (midi_channels > AM824_MAX_CHANNELS_FOR_MIDI)
+		return -EINVAL;
+
+	if (WARN_ON(amdtp_stream_running(s)) ||
+	    WARN_ON(pcm_channels > AM824_MAX_CHANNELS_FOR_PCM) ||
+	    WARN_ON(midi_channels > AM824_MAX_CHANNELS_FOR_MIDI))
+		return -EINVAL;
+
+	err = amdtp_stream_set_parameters(s, rate,
+					  pcm_channels + midi_channels);
 	if (err < 0)
 		return err;
 
 	s->fdf = AMDTP_FDF_AM824 | s->sfc;
 
+	p->pcm_channels = pcm_channels;
+	p->midi_ports = midi_ports;
+
 	/*
 	 * In IEC 61883-6, one data block represents one event. In ALSA, one
 	 * event equals to one PCM frame. But Dice has a quirk at higher
 	 * sampling rate to transfer two PCM frames in one data block.
 	 */
 	if (double_pcm_frames)
-		s->frame_multiplier = 2;
+		p->frame_multiplier = 2;
 	else
-		s->frame_multiplier = 1;
+		p->frame_multiplier = 1;
+
+	/* init the position map for PCM and MIDI channels */
+	for (i = 0; i < pcm_channels; i++)
+		p->pcm_positions[i] = i;
+	p->midi_position = p->pcm_channels;
+
+	/*
+	 * We do not know the actual MIDI FIFO size of most devices.  Just
+	 * assume two bytes, i.e., one byte can be received over the bus while
+	 * the previous one is transmitted over MIDI.
+	 * (The value here is adjusted for midi_ratelimit_per_packet().)
+	 */
+	p->midi_fifo_limit = rate - MIDI_BYTES_PER_SECOND * s->syt_interval + 1;
 
 	return 0;
 }
@@ -62,8 +129,10 @@ EXPORT_SYMBOL_GPL(amdtp_am824_set_parameters);
 void amdtp_am824_set_pcm_position(struct amdtp_stream *s, unsigned int index,
 				 unsigned int position)
 {
-	if (index < s->pcm_channels)
-		s->pcm_positions[index] = position;
+	struct amdtp_am824 *p = s->protocol;
+
+	if (index < p->pcm_channels)
+		p->pcm_positions[index] = position;
 }
 EXPORT_SYMBOL_GPL(amdtp_am824_set_pcm_position);
 
@@ -76,10 +145,139 @@ EXPORT_SYMBOL_GPL(amdtp_am824_set_pcm_position);
 void amdtp_am824_set_midi_position(struct amdtp_stream *s,
 				   unsigned int position)
 {
-	s->midi_position = position;
+	struct amdtp_am824 *p = s->protocol;
+
+	p->midi_position = position;
 }
 EXPORT_SYMBOL_GPL(amdtp_am824_set_midi_position);
 
+static void write_pcm_s32(struct amdtp_stream *s,
+			  struct snd_pcm_substream *pcm,
+			  __be32 *buffer, unsigned int frames)
+{
+	struct amdtp_am824 *p = s->protocol;
+	struct snd_pcm_runtime *runtime = pcm->runtime;
+	unsigned int channels, remaining_frames, i, c;
+	const u32 *src;
+
+	channels = p->pcm_channels;
+	src = (void *)runtime->dma_area +
+			frames_to_bytes(runtime, s->pcm_buffer_pointer);
+	remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
+
+	for (i = 0; i < frames; ++i) {
+		for (c = 0; c < channels; ++c) {
+			buffer[p->pcm_positions[c]] =
+					cpu_to_be32((*src >> 8) | 0x40000000);
+			src++;
+		}
+		buffer += s->data_block_quadlets;
+		if (--remaining_frames == 0)
+			src = (void *)runtime->dma_area;
+	}
+}
+
+static void write_pcm_s16(struct amdtp_stream *s,
+			  struct snd_pcm_substream *pcm,
+			  __be32 *buffer, unsigned int frames)
+{
+	struct amdtp_am824 *p = s->protocol;
+	struct snd_pcm_runtime *runtime = pcm->runtime;
+	unsigned int channels, remaining_frames, i, c;
+	const u16 *src;
+
+	channels = p->pcm_channels;
+	src = (void *)runtime->dma_area +
+			frames_to_bytes(runtime, s->pcm_buffer_pointer);
+	remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
+
+	for (i = 0; i < frames; ++i) {
+		for (c = 0; c < channels; ++c) {
+			buffer[p->pcm_positions[c]] =
+					cpu_to_be32((*src << 8) | 0x42000000);
+			src++;
+		}
+		buffer += s->data_block_quadlets;
+		if (--remaining_frames == 0)
+			src = (void *)runtime->dma_area;
+	}
+}
+
+static void read_pcm_s32(struct amdtp_stream *s,
+			 struct snd_pcm_substream *pcm,
+			 __be32 *buffer, unsigned int frames)
+{
+	struct amdtp_am824 *p = s->protocol;
+	struct snd_pcm_runtime *runtime = pcm->runtime;
+	unsigned int channels, remaining_frames, i, c;
+	u32 *dst;
+
+	channels = p->pcm_channels;
+	dst  = (void *)runtime->dma_area +
+			frames_to_bytes(runtime, s->pcm_buffer_pointer);
+	remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
+
+	for (i = 0; i < frames; ++i) {
+		for (c = 0; c < channels; ++c) {
+			*dst = be32_to_cpu(buffer[p->pcm_positions[c]]) << 8;
+			dst++;
+		}
+		buffer += s->data_block_quadlets;
+		if (--remaining_frames == 0)
+			dst = (void *)runtime->dma_area;
+	}
+}
+
+static void write_pcm_silence(struct amdtp_stream *s,
+			      __be32 *buffer, unsigned int frames)
+{
+	struct amdtp_am824 *p = s->protocol;
+	unsigned int i, c, channels = p->pcm_channels;
+
+	for (i = 0; i < frames; ++i) {
+		for (c = 0; c < channels; ++c)
+			buffer[p->pcm_positions[c]] = cpu_to_be32(0x40000000);
+		buffer += s->data_block_quadlets;
+	}
+}
+
+/**
+ * amdtp_am824_set_pcm_format - set the PCM format
+ * @s: the AMDTP stream to configure
+ * @format: the format of the ALSA PCM device
+ *
+ * The sample format must be set after the other parameters (rate/PCM channels/
+ * MIDI) and before the stream is started, and must not be changed while the
+ * stream is running.
+ */
+void amdtp_am824_set_pcm_format(struct amdtp_stream *s, snd_pcm_format_t format)
+{
+	struct amdtp_am824 *p = s->protocol;
+
+	if (WARN_ON(amdtp_stream_pcm_running(s)))
+		return;
+
+	switch (format) {
+	default:
+		WARN_ON(1);
+		/* fall through */
+	case SNDRV_PCM_FORMAT_S16:
+		if (s->direction == AMDTP_OUT_STREAM) {
+			p->transfer_samples = write_pcm_s16;
+			break;
+		}
+		WARN_ON(1);
+		/* fall through */
+	case SNDRV_PCM_FORMAT_S32:
+		if (s->direction == AMDTP_OUT_STREAM)
+			p->transfer_samples = write_pcm_s32;
+		else
+			p->transfer_samples = read_pcm_s32;
+		break;
+	}
+}
+EXPORT_SYMBOL_GPL(amdtp_am824_set_pcm_format);
+
 /**
  * amdtp_am824_add_pcm_hw_constraints - add hw constraints for PCM substream
  * @s:		the AMDTP stream for AM824 data block, must be initialized.
@@ -113,11 +311,135 @@ EXPORT_SYMBOL_GPL(amdtp_am824_add_pcm_hw_constraints);
 void amdtp_am824_midi_trigger(struct amdtp_stream *s, unsigned int port,
 			      struct snd_rawmidi_substream *midi)
 {
-	if (port < s->midi_ports)
-		ACCESS_ONCE(s->midi[port]) = midi;
+	struct amdtp_am824 *p = s->protocol;
+
+	if (port < p->midi_ports)
+		ACCESS_ONCE(p->midi[port]) = midi;
 }
 EXPORT_SYMBOL_GPL(amdtp_am824_midi_trigger);
 
+/*
+ * To avoid sending MIDI bytes at too high a rate, assume that the receiving
+ * device has a FIFO, and track how much it is filled.  This values increases
+ * by one whenever we send one byte in a packet, but the FIFO empties at
+ * a constant rate independent of our packet rate.  One packet has syt_interval
+ * samples, so the number of bytes that empty out of the FIFO, per packet(!),
+ * is MIDI_BYTES_PER_SECOND * syt_interval / sample_rate.  To avoid storing
+ * fractional values, the values in midi_fifo_used[] are measured in bytes
+ * multiplied by the sample rate.
+ */
+static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port)
+{
+	struct amdtp_am824 *p = s->protocol;
+	int used;
+
+	used = p->midi_fifo_used[port];
+	if (used == 0) /* common shortcut */
+		return true;
+
+	used -= MIDI_BYTES_PER_SECOND * s->syt_interval;
+	used = max(used, 0);
+	p->midi_fifo_used[port] = used;
+
+	return used < p->midi_fifo_limit;
+}
+
+static void midi_rate_use_one_byte(struct amdtp_stream *s, unsigned int port)
+{
+	struct amdtp_am824 *p = s->protocol;
+
+	p->midi_fifo_used[port] += amdtp_rate_table[s->sfc];
+}
+
+static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,
+				unsigned int frames)
+{
+	struct amdtp_am824 *p = s->protocol;
+	unsigned int f, port;
+	u8 *b;
+
+	for (f = 0; f < frames; f++) {
+		b = (u8 *)&buffer[p->midi_position];
+
+		port = (s->data_block_counter + f) % 8;
+		if (f < MAX_MIDI_RX_BLOCKS &&
+		    midi_ratelimit_per_packet(s, port) &&
+		    p->midi[port] != NULL &&
+		    snd_rawmidi_transmit(p->midi[port], &b[1], 1) == 1) {
+			midi_rate_use_one_byte(s, port);
+			b[0] = 0x81;
+		} else {
+			b[0] = 0x80;
+			b[1] = 0;
+		}
+		b[2] = 0;
+		b[3] = 0;
+
+		buffer += s->data_block_quadlets;
+	}
+}
+
+static void read_midi_messages(struct amdtp_stream *s,
+			       __be32 *buffer, unsigned int frames)
+{
+	struct amdtp_am824 *p = s->protocol;
+	unsigned int f, port;
+	int len;
+	u8 *b;
+
+	for (f = 0; f < frames; f++) {
+		port = (s->data_block_counter + f) % 8;
+		b = (u8 *)&buffer[p->midi_position];
+
+		len = b[0] - 0x80;
+		if ((1 <= len) &&  (len <= 3) && (p->midi[port]))
+			snd_rawmidi_receive(p->midi[port], b + 1, len);
+
+		buffer += s->data_block_quadlets;
+	}
+}
+
+unsigned int process_rx_data_blocks(struct amdtp_stream *s, __be32 *buffer,
+				    unsigned int data_blocks, unsigned int *syt)
+{
+	struct amdtp_am824 *p = s->protocol;
+	struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
+	unsigned int pcm_frames;
+
+	if (pcm) {
+		p->transfer_samples(s, pcm, buffer, data_blocks);
+		pcm_frames = data_blocks * p->frame_multiplier;
+	} else {
+		write_pcm_silence(s, buffer, data_blocks);
+		pcm_frames = 0;
+	}
+
+	if (p->midi_ports)
+		write_midi_messages(s, buffer, data_blocks);
+
+	return pcm_frames;
+}
+
+unsigned int process_tx_data_blocks(struct amdtp_stream *s, __be32 *buffer,
+				    unsigned int data_blocks, unsigned int *syt)
+{
+	struct amdtp_am824 *p = s->protocol;
+	struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
+	unsigned int pcm_frames;
+
+	if (pcm) {
+		p->transfer_samples(s, pcm, buffer, data_blocks);
+		pcm_frames = data_blocks * p->frame_multiplier;
+	} else {
+		pcm_frames = 0;
+	}
+
+	if (p->midi_ports)
+		read_midi_messages(s, buffer, data_blocks);
+
+	return pcm_frames;
+}
+
 /**
  * amdtp_am824_init - initialize an AMDTP stream structure to handle AM824
  *		      data block
@@ -129,6 +451,15 @@ EXPORT_SYMBOL_GPL(amdtp_am824_midi_trigger);
 int amdtp_am824_init(struct amdtp_stream *s, struct fw_unit *unit,
 		     enum amdtp_stream_direction dir, enum cip_flags flags)
 {
-	return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM);
+	amdtp_stream_process_data_blocks_t process_data_blocks;
+
+	if (dir == AMDTP_IN_STREAM)
+		process_data_blocks = process_tx_data_blocks;
+	else
+		process_data_blocks = process_rx_data_blocks;
+
+	return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,
+				 process_data_blocks,
+				 sizeof(struct amdtp_am824));
 }
 EXPORT_SYMBOL_GPL(amdtp_am824_init);