drivers/ieee1394/iso.h

   1 /*
   2  * IEEE 1394 for Linux
   3  *
   4  * kernel ISO transmission/reception
   5  *
   6  * Copyright (C) 2002 Maas Digital LLC
   7  *
   8  * This code is licensed under the GPL.  See the file COPYING in the root
   9  * directory of the kernel sources for details.
  10  */
  11
  12 #ifndef IEEE1394_ISO_H
  13 #define IEEE1394_ISO_H
  14
  15 #include "hosts.h"
  16 #include "dma.h"
  17
  18 /* high-level ISO interface */
  19
  20 /* This API sends and receives isochronous packets on a large,
  21    virtually-contiguous kernel memory buffer. The buffer may be mapped
  22    into a user-space process for zero-copy transmission and reception.
  23
  24    There are no explicit boundaries between packets in the buffer. A
  25    packet may be transmitted or received at any location. However,
  26    low-level drivers may impose certain restrictions on alignment or
  27    size of packets. (e.g. in OHCI no packet may cross a page boundary,
  28    and packets should be quadlet-aligned)
  29 */
  30
  31 /* Packet descriptor - the API maintains a ring buffer of these packet
  32    descriptors in kernel memory (hpsb_iso.infos[]).  */
  33
  34 struct hpsb_iso_packet_info {
  35         /* offset of data payload relative to the first byte of the buffer */
  36         __u32 offset;
  37
  38         /* length of the data payload, in bytes (not including the isochronous header) */
  39         __u16 len;
  40
  41         /* (recv only) the cycle number (mod 8000) on which the packet was received */
  42         __u16 cycle;
  43
  44         /* (recv only) channel on which the packet was received */
  45         __u8 channel;
  46
  47         /* 2-bit 'tag' and 4-bit 'sy' fields of the isochronous header */
  48         __u8 tag;
  49         __u8 sy;
  50 };
  51
  52 enum hpsb_iso_type { HPSB_ISO_RECV = 0, HPSB_ISO_XMIT = 1 };
  53
  54 struct hpsb_iso {
  55         enum hpsb_iso_type type;
  56
  57         /* pointer to low-level driver and its private data */
  58         struct hpsb_host *host;
  59         void *hostdata;
  60
  61         /* a function to be called (from interrupt context) after
  62            outgoing packets have been sent, or incoming packets have
  63            arrived */
  64         void (*callback)(struct hpsb_iso*);
  65
  66         /* wait for buffer space */
  67         wait_queue_head_t waitq;
  68
  69         int speed; /* IEEE1394_SPEED_100, 200, or 400 */
  70         int channel; /* -1 if multichannel */
  71
  72         /* greatest # of packets between interrupts - controls
  73            the maximum latency of the buffer */
  74         int irq_interval;
  75
  76         /* the buffer for packet data payloads */
  77         struct dma_region data_buf;
  78
  79         /* size of data_buf, in bytes (always a multiple of PAGE_SIZE) */
  80         unsigned int buf_size;
  81
  82         /* # of packets in the ringbuffer */
  83         unsigned int buf_packets;
  84
  85         /* protects packet cursors */
  86         spinlock_t lock;
  87
  88         /* the index of the next packet that will be produced
  89            or consumed by the user */
  90         int first_packet;
  91
  92         /* the index of the next packet that will be transmitted
  93            or received by the 1394 hardware */
  94         int pkt_dma;
  95
  96         /* how many packets, starting at first_packet:
  97            (transmit) are ready to be filled with data
  98            (receive)  contain received data */
  99         int n_ready_packets;
 100
 101         /* how many times the buffer has overflowed or underflowed */
 102         atomic_t overflows;
 103
 104         /* private flags to track initialization progress */
 105 #define HPSB_ISO_DRIVER_INIT     (1<<0)
 106 #define HPSB_ISO_DRIVER_STARTED  (1<<1)
 107         unsigned int flags;
 108
 109         /* # of packets left to prebuffer (xmit only) */
 110         int prebuffer;
 111
 112         /* starting cycle for DMA (xmit only) */
 113         int start_cycle;
 114
 115         /* cycle at which next packet will be transmitted,
 116            -1 if not known */
 117         int xmit_cycle;
 118
 119         /* ringbuffer of packet descriptors in regular kernel memory
 120          * XXX Keep this last, since we use over-allocated memory from
 121          * this entry to fill this field. */
 122         struct hpsb_iso_packet_info *infos;
 123 };
 124
 125 /* functions available to high-level drivers (e.g. raw1394) */
 126
 127 /* allocate the buffer and DMA context */
 128
 129 struct hpsb_iso* hpsb_iso_xmit_init(struct hpsb_host *host,
 130                                     unsigned int data_buf_size,
 131                                     unsigned int buf_packets,
 132                                     int channel,
 133                                     int speed,
 134                                     int irq_interval,
 135                                     void (*callback)(struct hpsb_iso*));
 136
 137 /* note: if channel = -1, multi-channel receive is enabled */
 138 struct hpsb_iso* hpsb_iso_recv_init(struct hpsb_host *host,
 139                                     unsigned int data_buf_size,
 140                                     unsigned int buf_packets,
 141                                     int channel,
 142                                     int irq_interval,
 143                                     void (*callback)(struct hpsb_iso*));
 144
 145 /* multi-channel only */
 146 int hpsb_iso_recv_listen_channel(struct hpsb_iso *iso, unsigned char channel);
 147 int hpsb_iso_recv_unlisten_channel(struct hpsb_iso *iso, unsigned char channel);
 148 int hpsb_iso_recv_set_channel_mask(struct hpsb_iso *iso, u64 mask);
 149
 150 /* start/stop DMA */
 151 int hpsb_iso_xmit_start(struct hpsb_iso *iso, int start_on_cycle, int prebuffer);
 152 int hpsb_iso_recv_start(struct hpsb_iso *iso, int start_on_cycle, int tag_mask, int sync);
 153 void hpsb_iso_stop(struct hpsb_iso *iso);
 154
 155 /* deallocate buffer and DMA context */
 156 void hpsb_iso_shutdown(struct hpsb_iso *iso);
 157
 158 /* queue a packet for transmission. 'offset' is relative to the beginning of the
 159    DMA buffer, where the packet's data payload should already have been placed */
 160 int hpsb_iso_xmit_queue_packet(struct hpsb_iso *iso, u32 offset, u16 len, u8 tag, u8 sy);
 161
 162 /* wait until all queued packets have been transmitted to the bus */
 163 int hpsb_iso_xmit_sync(struct hpsb_iso *iso);
 164
 165 /* N packets have been read out of the buffer, re-use the buffer space */
 166 int  hpsb_iso_recv_release_packets(struct hpsb_iso *recv, unsigned int n_packets);
 167
 168 /* returns # of packets ready to send or receive */
 169 int hpsb_iso_n_ready(struct hpsb_iso *iso);
 170
 171 /* the following are callbacks available to low-level drivers */
 172
 173 /* call after a packet has been transmitted to the bus (interrupt context is OK)
 174    'cycle' is the _exact_ cycle the packet was sent on
 175    'error' should be non-zero if some sort of error occurred when sending the packet
 176 */
 177 void hpsb_iso_packet_sent(struct hpsb_iso *iso, int cycle, int error);
 178
 179 /* call after a packet has been received (interrupt context OK) */
 180 void hpsb_iso_packet_received(struct hpsb_iso *iso, u32 offset, u16 len,
 181                               u16 cycle, u8 channel, u8 tag, u8 sy);
 182
 183 /* call to wake waiting processes after buffer space has opened up. */
 184 void hpsb_iso_wake(struct hpsb_iso *iso);
 185
 186 #endif /* IEEE1394_ISO_H */