esp_scsi.h

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/* esp_scsi.h: Defines and structures for the ESP drier.
 *
 * Copyright (C) 2007 David S. Miller ([email protected])
 */

#ifndef _ESP_SCSI_H
#define _ESP_SCSI_H

                    /* Access    Description      Offset */
#define ESP_TCLOW   0x00UL      /* rw  Low bits transfer count 0x00  */
#define ESP_TCMED   0x01UL      /* rw  Mid bits transfer count 0x04  */
#define ESP_FDATA   0x02UL      /* rw  FIFO data bits          0x08  */
#define ESP_CMD     0x03UL      /* rw  SCSI command bits       0x0c  */
#define ESP_STATUS  0x04UL      /* ro  ESP status register     0x10  */
#define ESP_BUSID   ESP_STATUS  /* wo  BusID for sel/resel     0x10  */
#define ESP_INTRPT  0x05UL      /* ro  Kind of interrupt       0x14  */
#define ESP_TIMEO   ESP_INTRPT  /* wo  Timeout for sel/resel   0x14  */
#define ESP_SSTEP   0x06UL      /* ro  Sequence step register  0x18  */
#define ESP_STP     ESP_SSTEP   /* wo  Transfer period/sync    0x18  */
#define ESP_FFLAGS  0x07UL      /* ro  Bits current FIFO info  0x1c  */
#define ESP_SOFF    ESP_FFLAGS  /* wo  Sync offset             0x1c  */
#define ESP_CFG1    0x08UL      /* rw  First cfg register      0x20  */
#define ESP_CFACT   0x09UL      /* wo  Clock conv factor       0x24  */
#define ESP_STATUS2 ESP_CFACT   /* ro  HME status2 register    0x24  */
#define ESP_CTEST   0x0aUL      /* wo  Chip test register      0x28  */
#define ESP_CFG2    0x0bUL      /* rw  Second cfg register     0x2c  */
#define ESP_CFG3    0x0cUL      /* rw  Third cfg register      0x30  */
#define ESP_TCHI    0x0eUL      /* rw  High bits transf count  0x38  */
#define ESP_UID     ESP_TCHI    /* ro  Unique ID code          0x38  */
#define FAS_RLO     ESP_TCHI    /* rw  HME extended counter    0x38  */
#define ESP_FGRND   0x0fUL      /* rw  Data base for fifo      0x3c  */
#define FAS_RHI     ESP_FGRND   /* rw  HME extended counter    0x3c  */

#define SBUS_ESP_REG_SIZE   0x40UL

/* Bitfield meanings for the above registers. */

/* ESP config reg 1, read-write, found on all ESP chips */
#define ESP_CONFIG1_ID        0x07      /* My BUS ID bits */
#define ESP_CONFIG1_CHTEST    0x08      /* Enable ESP chip tests */
#define ESP_CONFIG1_PENABLE   0x10      /* Enable parity checks */
#define ESP_CONFIG1_PARTEST   0x20      /* Parity test mode enabled? */
#define ESP_CONFIG1_SRRDISAB  0x40      /* Disable SCSI reset reports */
#define ESP_CONFIG1_SLCABLE   0x80      /* Enable slow cable mode */

/* ESP config reg 2, read-write, found only on esp100a+esp200+esp236 chips */
#define ESP_CONFIG2_DMAPARITY 0x01      /* enable DMA Parity (200,236) */
#define ESP_CONFIG2_REGPARITY 0x02      /* enable reg Parity (200,236) */
#define ESP_CONFIG2_BADPARITY 0x04      /* Bad parity target abort  */
#define ESP_CONFIG2_SCSI2ENAB 0x08      /* Enable SCSI-2 features (tgtmode) */
#define ESP_CONFIG2_HI        0x10      /* High Impedance DREQ ???  */
#define ESP_CONFIG2_HMEFENAB  0x10      /* HME features enable */
#define ESP_CONFIG2_BCM       0x20      /* Enable byte-ctrl (236)   */
#define ESP_CONFIG2_DISPINT   0x20      /* Disable pause irq (hme) */
#define ESP_CONFIG2_FENAB     0x40      /* Enable features (fas100,216) */
#define ESP_CONFIG2_SPL       0x40      /* Enable status-phase latch (236) */
#define ESP_CONFIG2_MKDONE    0x40      /* HME magic feature */
#define ESP_CONFIG2_HME32     0x80      /* HME 32 extended */
#define ESP_CONFIG2_MAGIC     0xe0      /* Invalid bits... */

/* ESP config register 3 read-write, found only esp236+fas236+fas100a+hme chips */
#define ESP_CONFIG3_FCLOCK    0x01     /* FAST SCSI clock rate (esp100a/hme) */
#define ESP_CONFIG3_TEM       0x01     /* Enable thresh-8 mode (esp/fas236)  */
#define ESP_CONFIG3_FAST      0x02     /* Enable FAST SCSI     (esp100a/hme) */
#define ESP_CONFIG3_ADMA      0x02     /* Enable alternate-dma (esp/fas236)  */
#define ESP_CONFIG3_TENB      0x04     /* group2 SCSI2 support (esp100a/hme) */
#define ESP_CONFIG3_SRB       0x04     /* Save residual byte   (esp/fas236)  */
#define ESP_CONFIG3_TMS       0x08     /* Three-byte msg's ok  (esp100a/hme) */
#define ESP_CONFIG3_FCLK      0x08     /* Fast SCSI clock rate (esp/fas236)  */
#define ESP_CONFIG3_IDMSG     0x10     /* ID message checking  (esp100a/hme) */
#define ESP_CONFIG3_FSCSI     0x10     /* Enable FAST SCSI     (esp/fas236)  */
#define ESP_CONFIG3_GTM       0x20     /* group2 SCSI2 support (esp/fas236)  */
#define ESP_CONFIG3_IDBIT3    0x20     /* Bit 3 of HME SCSI-ID (hme)         */
#define ESP_CONFIG3_TBMS      0x40     /* Three-byte msg's ok  (esp/fas236)  */
#define ESP_CONFIG3_EWIDE     0x40     /* Enable Wide-SCSI     (hme)         */
#define ESP_CONFIG3_IMS       0x80     /* ID msg chk'ng        (esp/fas236)  */
#define ESP_CONFIG3_OBPUSH    0x80     /* Push odd-byte to dma (hme)         */

/* ESP command register read-write */
/* Group 1 commands:  These may be sent at any point in time to the ESP
 *                    chip.  None of them can generate interrupts 'cept
 *                    the "SCSI bus reset" command if you have not disabled
 *                    SCSI reset interrupts in the config1 ESP register.
 */
#define ESP_CMD_NULL          0x00     /* Null command, ie. a nop */
#define ESP_CMD_FLUSH         0x01     /* FIFO Flush */
#define ESP_CMD_RC            0x02     /* Chip reset */
#define ESP_CMD_RS            0x03     /* SCSI bus reset */

/* Group 2 commands:  ESP must be an initiator and connected to a target
 *                    for these commands to work.
 */
#define ESP_CMD_TI            0x10     /* Transfer Information */
#define ESP_CMD_ICCSEQ        0x11     /* Initiator cmd complete sequence */
#define ESP_CMD_MOK           0x12     /* Message okie-dokie */
#define ESP_CMD_TPAD          0x18     /* Transfer Pad */
#define ESP_CMD_SATN          0x1a     /* Set ATN */
#define ESP_CMD_RATN          0x1b     /* De-assert ATN */

/* Group 3 commands:  ESP must be in the MSGOUT or MSGIN state and be connected
 *                    to a target as the initiator for these commands to work.
 */
#define ESP_CMD_SMSG          0x20     /* Send message */
#define ESP_CMD_SSTAT         0x21     /* Send status */
#define ESP_CMD_SDATA         0x22     /* Send data */
#define ESP_CMD_DSEQ          0x23     /* Discontinue Sequence */
#define ESP_CMD_TSEQ          0x24     /* Terminate Sequence */
#define ESP_CMD_TCCSEQ        0x25     /* Target cmd cmplt sequence */
#define ESP_CMD_DCNCT         0x27     /* Disconnect */
#define ESP_CMD_RMSG          0x28     /* Receive Message */
#define ESP_CMD_RCMD          0x29     /* Receive Command */
#define ESP_CMD_RDATA         0x2a     /* Receive Data */
#define ESP_CMD_RCSEQ         0x2b     /* Receive cmd sequence */

/* Group 4 commands:  The ESP must be in the disconnected state and must
 *                    not be connected to any targets as initiator for
 *                    these commands to work.
 */
#define ESP_CMD_RSEL          0x40     /* Reselect */
#define ESP_CMD_SEL           0x41     /* Select w/o ATN */
#define ESP_CMD_SELA          0x42     /* Select w/ATN */
#define ESP_CMD_SELAS         0x43     /* Select w/ATN & STOP */
#define ESP_CMD_ESEL          0x44     /* Enable selection */
#define ESP_CMD_DSEL          0x45     /* Disable selections */
#define ESP_CMD_SA3           0x46     /* Select w/ATN3 */
#define ESP_CMD_RSEL3         0x47     /* Reselect3 */

/* This bit enables the ESP's DMA on the SBus */
#define ESP_CMD_DMA           0x80     /* Do DMA? */

/* ESP status register read-only */
#define ESP_STAT_PIO          0x01     /* IO phase bit */
#define ESP_STAT_PCD          0x02     /* CD phase bit */
#define ESP_STAT_PMSG         0x04     /* MSG phase bit */
#define ESP_STAT_PMASK        0x07     /* Mask of phase bits */
#define ESP_STAT_TDONE        0x08     /* Transfer Completed */
#define ESP_STAT_TCNT         0x10     /* Transfer Counter Is Zero */
#define ESP_STAT_PERR         0x20     /* Parity error */
#define ESP_STAT_SPAM         0x40     /* Real bad error */
/* This indicates the 'interrupt pending' condition on esp236, it is a reserved
 * bit on other revs of the ESP.
 */
#define ESP_STAT_INTR         0x80             /* Interrupt */

/* The status register can be masked with ESP_STAT_PMASK and compared
 * with the following values to determine the current phase the ESP
 * (at least thinks it) is in.  For our purposes we also add our own
 * software 'done' bit for our phase management engine.
 */
#define ESP_DOP   (0)                                       /* Data Out  */
#define ESP_DIP   (ESP_STAT_PIO)                            /* Data In   */
#define ESP_CMDP  (ESP_STAT_PCD)                            /* Command   */
#define ESP_STATP (ESP_STAT_PCD|ESP_STAT_PIO)               /* Status    */
#define ESP_MOP   (ESP_STAT_PMSG|ESP_STAT_PCD)              /* Message Out */
#define ESP_MIP   (ESP_STAT_PMSG|ESP_STAT_PCD|ESP_STAT_PIO) /* Message In */

/* HME only: status 2 register */
#define ESP_STAT2_SCHBIT      0x01 /* Upper bits 3-7 of sstep enabled */
#define ESP_STAT2_FFLAGS      0x02 /* The fifo flags are now latched */
#define ESP_STAT2_XCNT        0x04 /* The transfer counter is latched */
#define ESP_STAT2_CREGA       0x08 /* The command reg is active now */
#define ESP_STAT2_WIDE        0x10 /* Interface on this adapter is wide */
#define ESP_STAT2_F1BYTE      0x20 /* There is one byte at top of fifo */
#define ESP_STAT2_FMSB        0x40 /* Next byte in fifo is most significant */
#define ESP_STAT2_FEMPTY      0x80 /* FIFO is empty */

/* ESP interrupt register read-only */
#define ESP_INTR_S            0x01     /* Select w/o ATN */
#define ESP_INTR_SATN         0x02     /* Select w/ATN */
#define ESP_INTR_RSEL         0x04     /* Reselected */
#define ESP_INTR_FDONE        0x08     /* Function done */
#define ESP_INTR_BSERV        0x10     /* Bus service */
#define ESP_INTR_DC           0x20     /* Disconnect */
#define ESP_INTR_IC           0x40     /* Illegal command given */
#define ESP_INTR_SR           0x80     /* SCSI bus reset detected */

/* ESP sequence step register read-only */
#define ESP_STEP_VBITS        0x07     /* Valid bits */
#define ESP_STEP_ASEL         0x00     /* Selection&Arbitrate cmplt */
#define ESP_STEP_SID          0x01     /* One msg byte sent */
#define ESP_STEP_NCMD         0x02     /* Was not in command phase */
#define ESP_STEP_PPC          0x03     /* Early phase chg caused cmnd
                                        * bytes to be lost
                                        */
#define ESP_STEP_FINI4        0x04     /* Command was sent ok */

/* Ho hum, some ESP's set the step register to this as well... */
#define ESP_STEP_FINI5        0x05
#define ESP_STEP_FINI6        0x06
#define ESP_STEP_FINI7        0x07

/* ESP chip-test register read-write */
#define ESP_TEST_TARG         0x01     /* Target test mode */
#define ESP_TEST_INI          0x02     /* Initiator test mode */
#define ESP_TEST_TS           0x04     /* Tristate test mode */

/* ESP unique ID register read-only, found on fas236+fas100a only */
#define ESP_UID_F100A         0x00     /* ESP FAS100A  */
#define ESP_UID_F236          0x02     /* ESP FAS236   */
#define ESP_UID_REV           0x07     /* ESP revision */
#define ESP_UID_FAM           0xf8     /* ESP family   */

/* ESP fifo flags register read-only */
/* Note that the following implies a 16 byte FIFO on the ESP. */
#define ESP_FF_FBYTES         0x1f     /* Num bytes in FIFO */
#define ESP_FF_ONOTZERO       0x20     /* offset ctr not zero (esp100) */
#define ESP_FF_SSTEP          0xe0     /* Sequence step */

/* ESP clock conversion factor register write-only */
#define ESP_CCF_F0            0x00     /* 35.01MHz - 40MHz */
#define ESP_CCF_NEVER         0x01     /* Set it to this and die */
#define ESP_CCF_F2            0x02     /* 10MHz */
#define ESP_CCF_F3            0x03     /* 10.01MHz - 15MHz */
#define ESP_CCF_F4            0x04     /* 15.01MHz - 20MHz */
#define ESP_CCF_F5            0x05     /* 20.01MHz - 25MHz */
#define ESP_CCF_F6            0x06     /* 25.01MHz - 30MHz */
#define ESP_CCF_F7            0x07     /* 30.01MHz - 35MHz */

/* HME only... */
#define ESP_BUSID_RESELID     0x10
#define ESP_BUSID_CTR32BIT    0x40

#define ESP_BUS_TIMEOUT        250     /* In milli-seconds */
#define ESP_TIMEO_CONST       8192
#define ESP_NEG_DEFP(mhz, cfact) \
        ((ESP_BUS_TIMEOUT * ((mhz) / 1000)) / (8192 * (cfact)))
#define ESP_HZ_TO_CYCLE(hertz)  ((1000000000) / ((hertz) / 1000))
#define ESP_TICK(ccf, cycle)  ((7682 * (ccf) * (cycle) / 1000))

/* For slow to medium speed input clock rates we shoot for 5mb/s, but for high
 * input clock rates we try to do 10mb/s although I don't think a transfer can
 * even run that fast with an ESP even with DMA2 scatter gather pipelining.
 */
#define SYNC_DEFP_SLOW            0x32   /* 5mb/s  */
#define SYNC_DEFP_FAST            0x19   /* 10mb/s */

struct esp_cmd_priv {
    union {
        dma_addr_t  dma_addr;
        int     num_sg;
    } u;

    int         cur_residue;
    struct scatterlist  *cur_sg;
    int         tot_residue;
};
#define ESP_CMD_PRIV(CMD)   ((struct esp_cmd_priv *)(&(CMD)->SCp))

enum esp_rev {
    ESP100     = 0x00,  /* NCR53C90 - very broken */
    ESP100A    = 0x01,  /* NCR53C90A */
    ESP236     = 0x02,
    FAS236     = 0x03,
    FAS100A    = 0x04,
    FAST       = 0x05,
    FASHME     = 0x06,
};

struct esp_cmd_entry {
    struct list_head    list;

    struct scsi_cmnd    *cmd;

    unsigned int        saved_cur_residue;
    struct scatterlist  *saved_cur_sg;
    unsigned int        saved_tot_residue;

    u8          flags;
#define ESP_CMD_FLAG_WRITE  0x01 /* DMA is a write */
#define ESP_CMD_FLAG_ABORT  0x02 /* being aborted */
#define ESP_CMD_FLAG_AUTOSENSE  0x04 /* Doing automatic REQUEST_SENSE */

    u8          tag[2];

    u8          status;
    u8          message;

    unsigned char       *sense_ptr;
    unsigned char       *saved_sense_ptr;
    dma_addr_t      sense_dma;

    struct completion   *eh_done;
};

/* XXX make this configurable somehow XXX */
#define ESP_DEFAULT_TAGS    16

#define ESP_MAX_TARGET      16
#define ESP_MAX_LUN     8
#define ESP_MAX_TAG     256

struct esp_lun_data {
    struct esp_cmd_entry    *non_tagged_cmd;
    int         num_tagged;
    int         hold;
    struct esp_cmd_entry    *tagged_cmds[ESP_MAX_TAG];
};

struct esp_target_data {
    /* These are the ESP_STP, ESP_SOFF, and ESP_CFG3 register values which
     * match the currently negotiated settings for this target.  The SCSI
     * protocol values are maintained in spi_{offset,period,wide}(starget).
     */
    u8          esp_period;
    u8          esp_offset;
    u8          esp_config3;

    u8          flags;
#define ESP_TGT_WIDE        0x01
#define ESP_TGT_DISCONNECT  0x02
#define ESP_TGT_NEGO_WIDE   0x04
#define ESP_TGT_NEGO_SYNC   0x08
#define ESP_TGT_CHECK_NEGO  0x40
#define ESP_TGT_BROKEN      0x80

    /* When ESP_TGT_CHECK_NEGO is set, on the next scsi command to this
     * device we will try to negotiate the following parameters.
     */
    u8          nego_goal_period;
    u8          nego_goal_offset;
    u8          nego_goal_width;
    u8          nego_goal_tags;

    struct scsi_target  *starget;
};

struct esp_event_ent {
    u8          type;
#define ESP_EVENT_TYPE_EVENT    0x01
#define ESP_EVENT_TYPE_CMD  0x02
    u8          val;

    u8          sreg;
    u8          seqreg;
    u8          sreg2;
    u8          ireg;
    u8          select_state;
    u8          event;
    u8          __pad;
};

struct esp;
struct esp_driver_ops {
    /* Read and write the ESP 8-bit registers.  On some
     * applications of the ESP chip the registers are at 4-byte
     * instead of 1-byte intervals.
     */
    void (*esp_write8)(struct esp *esp, u8 val, unsigned long reg);
    u8 (*esp_read8)(struct esp *esp, unsigned long reg);

    /* Map and unmap DMA memory.  Eventually the driver will be
     * converted to the generic DMA API as soon as SBUS is able to
     * cope with that.  At such time we can remove this.
     */
    dma_addr_t (*map_single)(struct esp *esp, void *buf,
                 size_t sz, int dir);
    int (*map_sg)(struct esp *esp, struct scatterlist *sg,
              int num_sg, int dir);
    void (*unmap_single)(struct esp *esp, dma_addr_t addr,
                 size_t sz, int dir);
    void (*unmap_sg)(struct esp *esp, struct scatterlist *sg,
             int num_sg, int dir);

    /* Return non-zero if there is an IRQ pending.  Usually this
     * status bit lives in the DMA controller sitting in front of
     * the ESP.  This has to be accurate or else the ESP interrupt
     * handler will not run.
     */
    int (*irq_pending)(struct esp *esp);

    /* Return the maximum allowable size of a DMA transfer for a
     * given buffer.
     */
    u32 (*dma_length_limit)(struct esp *esp, u32 dma_addr,
                u32 dma_len);

    /* Reset the DMA engine entirely.  On return, ESP interrupts
     * should be enabled.  Often the interrupt enabling is
     * controlled in the DMA engine.
     */
    void (*reset_dma)(struct esp *esp);

    /* Drain any pending DMA in the DMA engine after a transfer.
     * This is for writes to memory.
     */
    void (*dma_drain)(struct esp *esp);

    /* Invalidate the DMA engine after a DMA transfer.  */
    void (*dma_invalidate)(struct esp *esp);

    /* Setup an ESP command that will use a DMA transfer.
     * The 'esp_count' specifies what transfer length should be
     * programmed into the ESP transfer counter registers, whereas
     * the 'dma_count' is the length that should be programmed into
     * the DMA controller.  Usually they are the same.  If 'write'
     * is non-zero, this transfer is a write into memory.  'cmd'
     * holds the ESP command that should be issued by calling
     * scsi_esp_cmd() at the appropriate time while programming
     * the DMA hardware.
     */
    void (*send_dma_cmd)(struct esp *esp, u32 dma_addr, u32 esp_count,
                 u32 dma_count, int write, u8 cmd);

    /* Return non-zero if the DMA engine is reporting an error
     * currently.
     */
    int (*dma_error)(struct esp *esp);
};

#define ESP_MAX_MSG_SZ      8
#define ESP_EVENT_LOG_SZ    32

#define ESP_QUICKIRQ_LIMIT  100
#define ESP_RESELECT_TAG_LIMIT  2500

struct esp {
    void __iomem        *regs;
    void __iomem        *dma_regs;

    const struct esp_driver_ops *ops;

    struct Scsi_Host    *host;
    void            *dev;

    struct esp_cmd_entry    *active_cmd;

    struct list_head    queued_cmds;
    struct list_head    active_cmds;

    u8          *command_block;
    dma_addr_t      command_block_dma;

    unsigned int        data_dma_len;

    /* The following are used to determine the cause of an IRQ. Upon every
     * IRQ entry we synchronize these with the hardware registers.
     */
    u8          sreg;
    u8          seqreg;
    u8          sreg2;
    u8          ireg;

    u32         prev_hme_dmacsr;
    u8          prev_soff;
    u8          prev_stp;
    u8          prev_cfg3;
    u8          __pad;

    struct list_head    esp_cmd_pool;

    struct esp_target_data  target[ESP_MAX_TARGET];

    int         fifo_cnt;
    u8          fifo[16];

    struct esp_event_ent    esp_event_log[ESP_EVENT_LOG_SZ];
    int         esp_event_cur;

    u8          msg_out[ESP_MAX_MSG_SZ];
    int         msg_out_len;

    u8          msg_in[ESP_MAX_MSG_SZ];
    int         msg_in_len;

    u8          bursts;
    u8          config1;
    u8          config2;

    u8          scsi_id;
    u32         scsi_id_mask;

    enum esp_rev        rev;

    u32         flags;
#define ESP_FLAG_DIFFERENTIAL   0x00000001
#define ESP_FLAG_RESETTING  0x00000002
#define ESP_FLAG_DOING_SLOWCMD  0x00000004
#define ESP_FLAG_WIDE_CAPABLE   0x00000008
#define ESP_FLAG_QUICKIRQ_CHECK 0x00000010
#define ESP_FLAG_DISABLE_SYNC   0x00000020

    u8          select_state;
#define ESP_SELECT_NONE     0x00 /* Not selecting */
#define ESP_SELECT_BASIC    0x01 /* Select w/o MSGOUT phase */
#define ESP_SELECT_MSGOUT   0x02 /* Select with MSGOUT */

    /* When we are not selecting, we are expecting an event.  */
    u8          event;
#define ESP_EVENT_NONE      0x00
#define ESP_EVENT_CMD_START 0x01
#define ESP_EVENT_CMD_DONE  0x02
#define ESP_EVENT_DATA_IN   0x03
#define ESP_EVENT_DATA_OUT  0x04
#define ESP_EVENT_DATA_DONE 0x05
#define ESP_EVENT_MSGIN     0x06
#define ESP_EVENT_MSGIN_MORE    0x07
#define ESP_EVENT_MSGIN_DONE    0x08
#define ESP_EVENT_MSGOUT    0x09
#define ESP_EVENT_MSGOUT_DONE   0x0a
#define ESP_EVENT_STATUS    0x0b
#define ESP_EVENT_FREE_BUS  0x0c
#define ESP_EVENT_CHECK_PHASE   0x0d
#define ESP_EVENT_RESET     0x10

    /* Probed in esp_get_clock_params() */
    u32         cfact;
    u32         cfreq;
    u32         ccycle;
    u32         ctick;
    u32         neg_defp;
    u32         sync_defp;

    /* Computed in esp_reset_esp() */
    u32         max_period;
    u32         min_period;
    u32         radelay;

    /* Slow command state.  */
    u8          *cmd_bytes_ptr;
    int         cmd_bytes_left;

    struct completion   *eh_reset;

    void            *dma;
    int         dmarev;
};

/* A front-end driver for the ESP chip should do the following in
 * it's device probe routine:
 * 1) Allocate the host and private area using scsi_host_alloc()
 *    with size 'sizeof(struct esp)'.  The first argument to
 *    scsi_host_alloc() should be &scsi_esp_template.
 * 2) Set host->max_id as appropriate.
 * 3) Set esp->host to the scsi_host itself, and esp->dev
 *    to the device object pointer.
 * 4) Hook up esp->ops to the front-end implementation.
 * 5) If the ESP chip supports wide transfers, set ESP_FLAG_WIDE_CAPABLE
 *    in esp->flags.
 * 6) Map the DMA and ESP chip registers.
 * 7) DMA map the ESP command block, store the DMA address
 *    in esp->command_block_dma.
 * 8) Register the scsi_esp_intr() interrupt handler.
 * 9) Probe for and provide the following chip properties:
 *    esp->scsi_id (assign to esp->host->this_id too)
 *    esp->scsi_id_mask
 *    If ESP bus is differential, set ESP_FLAG_DIFFERENTIAL
 *    esp->cfreq
 *    DMA burst bit mask in esp->bursts, if necessary
 * 10) Perform any actions necessary before the ESP device can
 *     be programmed for the first time.  On some configs, for
 *     example, the DMA engine has to be reset before ESP can
 *     be programmed.
 * 11) If necessary, call dev_set_drvdata() as needed.
 * 12) Call scsi_esp_register() with prepared 'esp' structure
 *     and a device pointer if possible.
 * 13) Check scsi_esp_register() return value, release all resources
 *     if an error was returned.
 */
extern struct scsi_host_template scsi_esp_template;
extern int scsi_esp_register(struct esp *, struct device *);

extern void scsi_esp_unregister(struct esp *);
extern irqreturn_t scsi_esp_intr(int, void *);
extern void scsi_esp_cmd(struct esp *, u8);

#endif /* !(_ESP_SCSI_H) */