sound/firewire/oxfw/oxfw-scs1x.c

Source file repositories/reference/linux-study-clean/sound/firewire/oxfw/oxfw-scs1x.c

File Facts

System
Linux kernel
Corpus path
sound/firewire/oxfw/oxfw-scs1x.c
Extension
.c
Size
10545 bytes
Lines
421
Domain
Driver Families
Bucket
sound/firewire
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct fw_scs1x {
	struct fw_address_handler hss_handler;
	u8 input_escape_count;
	struct snd_rawmidi_substream *input;

	/* For MIDI playback. */
	struct snd_rawmidi_substream *output;
	bool output_idle;
	u8 output_status;
	u8 output_bytes;
	bool output_escaped;
	bool output_escape_high_nibble;
	struct work_struct work;
	wait_queue_head_t idle_wait;
	u8 buffer[HSS1394_MAX_PACKET_SIZE];
	bool transaction_running;
	struct fw_transaction transaction;
	unsigned int transaction_bytes;
	bool error;
	struct fw_device *fw_dev;
};

static const u8 sysex_escape_prefix[] = {
	0xf0,			/* SysEx begin */
	0x00, 0x01, 0x60,	/* Stanton DJ */
	0x48, 0x53, 0x53,	/* "HSS" */
};

static void midi_input_escaped_byte(struct snd_rawmidi_substream *stream,
				    u8 byte)
{
	u8 nibbles[2];

	nibbles[0] = byte >> 4;
	nibbles[1] = byte & 0x0f;
	snd_rawmidi_receive(stream, nibbles, 2);
}

static void midi_input_byte(struct fw_scs1x *scs,
			    struct snd_rawmidi_substream *stream, u8 byte)
{
	const u8 eox = 0xf7;

	if (scs->input_escape_count > 0) {
		midi_input_escaped_byte(stream, byte);
		scs->input_escape_count--;
		if (scs->input_escape_count == 0)
			snd_rawmidi_receive(stream, &eox, sizeof(eox));
	} else if (byte == 0xf9) {
		snd_rawmidi_receive(stream, sysex_escape_prefix,
				    ARRAY_SIZE(sysex_escape_prefix));
		midi_input_escaped_byte(stream, 0x00);
		midi_input_escaped_byte(stream, 0xf9);
		scs->input_escape_count = 3;
	} else {
		snd_rawmidi_receive(stream, &byte, 1);
	}
}

static void midi_input_packet(struct fw_scs1x *scs,
			      struct snd_rawmidi_substream *stream,
			      const u8 *data, unsigned int bytes)
{
	unsigned int i;
	const u8 eox = 0xf7;

	if (data[0] == HSS1394_TAG_USER_DATA) {
		for (i = 1; i < bytes; ++i)
			midi_input_byte(scs, stream, data[i]);
	} else {
		snd_rawmidi_receive(stream, sysex_escape_prefix,
				    ARRAY_SIZE(sysex_escape_prefix));
		for (i = 0; i < bytes; ++i)
			midi_input_escaped_byte(stream, data[i]);
		snd_rawmidi_receive(stream, &eox, sizeof(eox));
	}
}

static void handle_hss(struct fw_card *card, struct fw_request *request,
		       int tcode, int destination, int source, int generation,
		       unsigned long long offset, void *data, size_t length,
		       void *callback_data)
{
	struct fw_scs1x *scs = callback_data;
	struct snd_rawmidi_substream *stream;
	int rcode;

	if (offset != scs->hss_handler.offset) {
		rcode = RCODE_ADDRESS_ERROR;
		goto end;

Annotation

Implementation Notes