ALSA: snd-usb: implement new endpoint streaming model

This patch adds a new generic streaming logic for audio over USB.

It defines a model (snd_usb_endpoint) that handles everything that
is related to an USB endpoint and its streaming. There are functions to
activate and deactivate an endpoint (which call usb_set_interface()),
and to start and stop its URBs. It also has function pointers to be
called when data was received or is about to be sent, and pointer to
a sync slave (another snd_usb_endpoint) that is informed when data has
been received.

A snd_usb_endpoint knows about its state and implements a refcounting,
so only the first user will actually start the URBs and only the last
one to stop it will tear them down again.

With this sort of abstraction, the actual streaming is decoupled from
the pcm handling, which makes the "implicit feedback" mechanisms easy to
implement.

In order to split changes properly, this patch only adds the new
implementation but leaves the old one around, so the the driver doesn't
change its behaviour. The switch to actually use the new code is
submitted separately.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 58 insertions, 0 deletions

diff --git a/sound/usb/card.h b/sound/usb/card.h
index da5fa1a..9acbd4a 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -30,13 +30,17 @@ struct audioformat {
 };
 
 struct snd_usb_substream;
+struct snd_usb_endpoint;
 
 struct snd_urb_ctx {
 	struct urb *urb;
 	unsigned int buffer_size;	/* size of data buffer, if data URB */
 	struct snd_usb_substream *subs;
+	struct snd_usb_endpoint *ep;
 	int index;	/* index for urb array */
 	int packets;	/* number of packets per urb */
+	int packet_size[MAX_PACKS_HS]; /* size of packets for next submission */
+	struct list_head ready_list;
 };
 
 struct snd_urb_ops {
@@ -46,6 +50,60 @@ struct snd_urb_ops {
 	int (*retire_sync)(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime, struct urb *u);
 };
 
+struct snd_usb_endpoint {
+	struct snd_usb_audio *chip;
+
+	int use_count;
+	int ep_num;		/* the referenced endpoint number */
+	int type;		/* SND_USB_ENDPOINT_TYPE_* */
+	unsigned long flags;
+
+	void (*prepare_data_urb) (struct snd_usb_substream *subs,
+				  struct urb *urb);
+	void (*retire_data_urb) (struct snd_usb_substream *subs,
+				 struct urb *urb);
+
+	struct snd_usb_substream *data_subs;
+	struct snd_usb_endpoint *sync_master;
+	struct snd_usb_endpoint *sync_slave;
+
+	struct snd_urb_ctx urb[MAX_URBS];
+
+	struct snd_usb_packet_info {
+		uint32_t packet_size[MAX_PACKS_HS];
+		int packets;
+	} next_packet[MAX_URBS];
+	int next_packet_read_pos, next_packet_write_pos;
+	struct list_head ready_playback_urbs;
+
+	unsigned int nurbs;		/* # urbs */
+	unsigned long active_mask;	/* bitmask of active urbs */
+	unsigned long unlink_mask;	/* bitmask of unlinked urbs */
+	char *syncbuf;			/* sync buffer for all sync URBs */
+	dma_addr_t sync_dma;		/* DMA address of syncbuf */
+
+	unsigned int pipe;		/* the data i/o pipe */
+	unsigned int freqn;		/* nominal sampling rate in fs/fps in Q16.16 format */
+	unsigned int freqm;		/* momentary sampling rate in fs/fps in Q16.16 format */
+	int	   freqshift;		/* how much to shift the feedback value to get Q16.16 */
+	unsigned int freqmax;		/* maximum sampling rate, used for buffer management */
+	unsigned int phase;		/* phase accumulator */
+	unsigned int maxpacksize;	/* max packet size in bytes */
+	unsigned int maxframesize;      /* max packet size in frames */
+	unsigned int curpacksize;	/* current packet size in bytes (for capture) */
+	unsigned int curframesize;      /* current packet size in frames (for capture) */
+	unsigned int syncmaxsize;	/* sync endpoint packet size */
+	unsigned int fill_max:1;	/* fill max packet size always */
+	unsigned int datainterval;      /* log_2 of data packet interval */
+	unsigned int syncinterval;	/* P for adaptive mode, 0 otherwise */
+	unsigned char silence_value;
+	unsigned int stride;
+	int iface, alt_idx;
+
+	spinlock_t lock;
+	struct list_head list;
+};
+
 struct snd_usb_substream {
 	struct snd_usb_stream *stream;
 	struct usb_device *dev;