iso.h

1394在linux下单独的驱动程序代码

/*
* IEEE 1394 for Linux
*
* kernel ISO transmission/reception
*
* Copyright (C) 2002 Maas Digital LLC
*
* This code is licensed under the GPL.  See the file COPYING in the root
* directory of the kernel sources for details.
*/

#ifndef IEEE1394_ISO_H
#define IEEE1394_ISO_H

#include "hosts.h"
#include "dma.h"

/* high-level ISO interface */

/* This API sends and receives isochronous packets on a large,
virtually-contiguous kernel memory buffer. The buffer may be mapped
into a user-space process for zero-copy transmission and reception.

 There are no explicit boundaries between packets in the buffer. A
 packet may be transmitted or received at any location. However,
 low-level drivers may impose certain restrictions on alignment or
 size of packets. (e.g. in OHCI no packet may cross a page boundary,
 and packets should be quadlet-aligned)
*/

/* Packet descriptor - the API maintains a ring buffer of these packet
descriptors in kernel memory (hpsb_iso.infos[]).  */

struct hpsb_iso_packet_info {
	/* offset of data payload relative to the first byte of the buffer */
	__u32 offset;
	
	/* length of the data payload, in bytes (not including the isochronous header) */
	__u16 len;
	
	/* (recv only) the cycle number (mod 8000) on which the packet was received */
	__u16 cycle;
	
	/* (recv only) channel on which the packet was received */
	__u8 channel;
	
	/* 2-bit 'tag' and 4-bit 'sy' fields of the isochronous header */
	__u8 tag;
	__u8 sy;
};

enum hpsb_iso_type { HPSB_ISO_RECV = 0, HPSB_ISO_XMIT = 1 };

struct hpsb_iso {
	enum hpsb_iso_type type;
	
	/* pointer to low-level driver and its private data */
	struct hpsb_host *host;
	void *hostdata;
	
	/* a function to be called (from interrupt context) after
	outgoing packets have been sent, or incoming packets have
	arrived */
	void (*callback)(struct hpsb_iso*);
	
	/* wait for buffer space */
	wait_queue_head_t waitq;
	
	int speed; /* IEEE1394_SPEED_100, 200, or 400 */
	int channel; /* -1 if multichannel */
	
				 /* greatest # of packets between interrupts - controls
	   the maximum latency of the buffer */
	int irq_interval;
	
	/* the buffer for packet data payloads */
	struct dma_region data_buf;
	
	/* size of data_buf, in bytes (always a multiple of PAGE_SIZE) */
	unsigned int buf_size;
	
	/* # of packets in the ringbuffer */
	unsigned int buf_packets;
	
	/* protects packet cursors */
	spinlock_t lock;
	
	/* the index of the next packet that will be produced
	   or consumed by the user */
	int first_packet;
	
	/* the index of the next packet that will be transmitted
	   or received by the 1394 hardware */
	int pkt_dma;
	
	/* how many packets, starting at first_packet:
	   (transmit) are ready to be filled with data
	   (receive)  contain received data */
	int n_ready_packets;
	
	/* how many times the buffer has overflowed or underflowed */
	atomic_t overflows;
	
	/* private flags to track initialization progress */
#define HPSB_ISO_DRIVER_INIT     (1<<0)
#define HPSB_ISO_DRIVER_STARTED  (1<<1)
	unsigned int flags;
	
	/* # of packets left to prebuffer (xmit only) */
	int prebuffer;
	
	/* starting cycle for DMA (xmit only) */
	int start_cycle;
	
	/* cycle at which next packet will be transmitted,
	   -1 if not known */
	int xmit_cycle;
	
	/* ringbuffer of packet descriptors in regular kernel memory
	* XXX Keep this last, since we use over-allocated memory from
	* this entry to fill this field. */
	struct hpsb_iso_packet_info *infos;
};

/* functions available to high-level drivers (e.g. raw1394) */

/* allocate the buffer and DMA context */

struct hpsb_iso* hpsb_iso_xmit_init(struct hpsb_host *host,
									unsigned int data_buf_size,
									unsigned int buf_packets,
									int channel,
									int speed,
									int irq_interval,
									void (*callback)(struct hpsb_iso*));

/* note: if channel = -1, multi-channel receive is enabled */
struct hpsb_iso* hpsb_iso_recv_init(struct hpsb_host *host,
									unsigned int data_buf_size,
									unsigned int buf_packets,
									int channel,
									int irq_interval,
									void (*callback)(struct hpsb_iso*));

/* multi-channel only */
int hpsb_iso_recv_listen_channel(struct hpsb_iso *iso, unsigned char channel);
int hpsb_iso_recv_unlisten_channel(struct hpsb_iso *iso, unsigned char channel);
int hpsb_iso_recv_set_channel_mask(struct hpsb_iso *iso, u64 mask);

/* start/stop DMA */
int hpsb_iso_xmit_start(struct hpsb_iso *iso, int start_on_cycle, int prebuffer);
int hpsb_iso_recv_start(struct hpsb_iso *iso, int start_on_cycle, int tag_mask, int sync);
void hpsb_iso_stop(struct hpsb_iso *iso);

/* deallocate buffer and DMA context */
void hpsb_iso_shutdown(struct hpsb_iso *iso);

/* queue a packet for transmission. 'offset' is relative to the beginning of the
DMA buffer, where the packet's data payload should already have been placed */
int hpsb_iso_xmit_queue_packet(struct hpsb_iso *iso, u32 offset, u16 len, u8 tag, u8 sy);

/* wait until all queued packets have been transmitted to the bus */
int hpsb_iso_xmit_sync(struct hpsb_iso *iso);

/* N packets have been read out of the buffer, re-use the buffer space */
int  hpsb_iso_recv_release_packets(struct hpsb_iso *recv, unsigned int n_packets);

/* check for arrival of new packets immediately (even if irq_interval
has not yet been reached) */
int hpsb_iso_recv_flush(struct hpsb_iso *iso);

/* returns # of packets ready to send or receive */
int hpsb_iso_n_ready(struct hpsb_iso *iso);

/* the following are callbacks available to low-level drivers */

/* call after a packet has been transmitted to the bus (interrupt context is OK)
'cycle' is the _exact_ cycle the packet was sent on
'error' should be non-zero if some sort of error occurred when sending the packet
*/
void hpsb_iso_packet_sent(struct hpsb_iso *iso, int cycle, int error);

/* call after a packet has been received (interrupt context OK) */
void hpsb_iso_packet_received(struct hpsb_iso *iso, u32 offset, u16 len,
							  u16 cycle, u8 channel, u8 tag, u8 sy);

/* call to wake waiting processes after buffer space has opened up. */
void hpsb_iso_wake(struct hpsb_iso *iso);

#endif /* IEEE1394_ISO_H */