remarkable-linux/drivers/ieee1394/iso.h

/*
 * 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;

	/*
	 * length in bytes of the packet including header/trailer.
	 * MUST be at structure end, since the first part of this structure is also 
	 * defined in raw1394.h (i.e. struct raw1394_iso_packet_info), is copied to 
	 * userspace and is accessed there through libraw1394. 
	 */
	__u16 total_len;
};

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

/* The mode of the dma when receiving iso data. Must be supported by chip */
enum raw1394_iso_dma_recv_mode {
	HPSB_ISO_DMA_DEFAULT = -1,
	HPSB_ISO_DMA_OLD_ABI = 0,
	HPSB_ISO_DMA_BUFFERFILL = 1,
	HPSB_ISO_DMA_PACKET_PER_BUFFER = 2
};

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 */
	int dma_mode; /* dma receive mode */


	/* 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;

	/* Current number of bytes lost in discarded packets */
	int bytes_discarded;

	/* 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 dma_mode,
				    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 total_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 */