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atari_scsi.c

/*
 * atari_scsi.c -- Device dependent functions for the Atari generic SCSI port
 *
 * Copyright 1994 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de>
 *
 *   Loosely based on the work of Robert De Vries' team and added:
 *    - working real DMA
 *    - Falcon support (untested yet!)   ++bjoern fixed and now it works
 *    - lots of extensions and bug fixes.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 *
 */


/**************************************************************************/
/*                                                                        */
/* Notes for Falcon SCSI:                                                 */
/* ----------------------                                                 */
/*                                                                        */
/* Since the Falcon SCSI uses the ST-DMA chip, that is shared among       */
/* several device drivers, locking and unlocking the access to this       */
/* chip is required. But locking is not possible from an interrupt,       */
/* since it puts the process to sleep if the lock is not available.       */
/* This prevents "late" locking of the DMA chip, i.e. locking it just     */
/* before using it, since in case of disconnection-reconnection           */
/* commands, the DMA is started from the reselection interrupt.           */
/*                                                                        */
/* Two possible schemes for ST-DMA-locking would be:                      */
/*  1) The lock is taken for each command separately and disconnecting    */
/*     is forbidden (i.e. can_queue = 1).                                 */
/*  2) The DMA chip is locked when the first command comes in and         */
/*     released when the last command is finished and all queues are      */
/*     empty.                                                             */
/* The first alternative would result in bad performance, since the       */
/* interleaving of commands would not be used. The second is unfair to    */
/* other drivers using the ST-DMA, because the queues will seldom be      */
/* totally empty if there is a lot of disk traffic.                       */
/*                                                                        */
/* For this reasons I decided to employ a more elaborate scheme:          */
/*  - First, we give up the lock every time we can (for fairness), this    */
/*    means every time a command finishes and there are no other commands */
/*    on the disconnected queue.                                          */
/*  - If there are others waiting to lock the DMA chip, we stop           */
/*    issuing commands, i.e. moving them onto the issue queue.           */
/*    Because of that, the disconnected queue will run empty in a         */
/*    while. Instead we go to sleep on a 'fairness_queue'.                */
/*  - If the lock is released, all processes waiting on the fairness      */
/*    queue will be woken. The first of them tries to re-lock the DMA,     */
/*    the others wait for the first to finish this task. After that,      */
/*    they can all run on and do their commands...                        */
/* This sounds complicated (and it is it :-(), but it seems to be a       */
/* good compromise between fairness and performance: As long as no one     */
/* else wants to work with the ST-DMA chip, SCSI can go along as          */
/* usual. If now someone else comes, this behaviour is changed to a       */
/* "fairness mode": just already initiated commands are finished and      */
/* then the lock is released. The other one waiting will probably win     */
/* the race for locking the DMA, since it was waiting for longer. And     */
/* after it has finished, SCSI can go ahead again. Finally: I hope I      */
/* have not produced any deadlock possibilities!                          */
/*                                                                        */
/**************************************************************************/



#include <linux/module.h>

#define NDEBUG (0)

#define NDEBUG_ABORT          0x00100000
#define NDEBUG_TAGS           0x00200000
#define NDEBUG_MERGING        0x00400000

#define AUTOSENSE
/* For the Atari version, use only polled IO or REAL_DMA */
#define     REAL_DMA
/* Support tagged queuing? (on devices that are able to... :-) */
#define     SUPPORT_TAGS
#define     MAX_TAGS 32

#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/mm.h>
#include <linux/blkdev.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/nvram.h>
#include <linux/bitops.h>

#include <asm/setup.h>
#include <asm/atarihw.h>
#include <asm/atariints.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/irq.h>
#include <asm/traps.h>

#include "scsi.h"
#include <scsi/scsi_host.h>
#include "atari_scsi.h"
#include "NCR5380.h"
#include <asm/atari_stdma.h>
#include <asm/atari_stram.h>
#include <asm/io.h>

#include <linux/stat.h>

#define     IS_A_TT()   ATARIHW_PRESENT(TT_SCSI)

#define     SCSI_DMA_WRITE_P(elt,val)                       \
      do {                                      \
            unsigned long v = val;                    \
            tt_scsi_dma.elt##_lo = v & 0xff;          \
            v >>= 8;                            \
            tt_scsi_dma.elt##_lmd = v & 0xff;         \
            v >>= 8;                            \
            tt_scsi_dma.elt##_hmd = v & 0xff;         \
            v >>= 8;                            \
            tt_scsi_dma.elt##_hi = v & 0xff;          \
      } while(0)

#define     SCSI_DMA_READ_P(elt)                            \
      (((((((unsigned long)tt_scsi_dma.elt##_hi << 8) |     \
           (unsigned long)tt_scsi_dma.elt##_hmd) << 8) |    \
         (unsigned long)tt_scsi_dma.elt##_lmd) << 8) |      \
       (unsigned long)tt_scsi_dma.elt##_lo)


static inline void SCSI_DMA_SETADR(unsigned long adr)
{
      st_dma.dma_lo = (unsigned char)adr;
      MFPDELAY();
      adr >>= 8;
      st_dma.dma_md = (unsigned char)adr;
      MFPDELAY();
      adr >>= 8;
      st_dma.dma_hi = (unsigned char)adr;
      MFPDELAY();
}

static inline unsigned long SCSI_DMA_GETADR(void)
{
      unsigned long adr;
      adr = st_dma.dma_lo;
      MFPDELAY();
      adr |= (st_dma.dma_md & 0xff) << 8;
      MFPDELAY();
      adr |= (st_dma.dma_hi & 0xff) << 16;
      MFPDELAY();
      return adr;
}

static inline void ENABLE_IRQ(void)
{
      if (IS_A_TT())
            atari_enable_irq(IRQ_TT_MFP_SCSI);
      else
            atari_enable_irq(IRQ_MFP_FSCSI);
}

static inline void DISABLE_IRQ(void)
{
      if (IS_A_TT())
            atari_disable_irq(IRQ_TT_MFP_SCSI);
      else
            atari_disable_irq(IRQ_MFP_FSCSI);
}


#define HOSTDATA_DMALEN       (((struct NCR5380_hostdata *) \
                        (atari_scsi_host->hostdata))->dma_len)

/* Time (in jiffies) to wait after a reset; the SCSI standard calls for 250ms,
 * we usually do 0.5s to be on the safe side. But Toshiba CD-ROMs once more
 * need ten times the standard value... */
#ifndef CONFIG_ATARI_SCSI_TOSHIBA_DELAY
#define     AFTER_RESET_DELAY (HZ/2)
#else
#define     AFTER_RESET_DELAY (5*HZ/2)
#endif

/***************************** Prototypes *****************************/

#ifdef REAL_DMA
static int scsi_dma_is_ignored_buserr(unsigned char dma_stat);
static void atari_scsi_fetch_restbytes(void);
static long atari_scsi_dma_residual(struct Scsi_Host *instance);
static int falcon_classify_cmd(Scsi_Cmnd *cmd);
static unsigned long atari_dma_xfer_len(unsigned long wanted_len,
                              Scsi_Cmnd *cmd, int write_flag);
#endif
static irqreturn_t scsi_tt_intr(int irq, void *dummy);
static irqreturn_t scsi_falcon_intr(int irq, void *dummy);
static void falcon_release_lock_if_possible(struct NCR5380_hostdata *hostdata);
static void falcon_get_lock(void);
#ifdef CONFIG_ATARI_SCSI_RESET_BOOT
static void atari_scsi_reset_boot(void);
#endif
static unsigned char atari_scsi_tt_reg_read(unsigned char reg);
static void atari_scsi_tt_reg_write(unsigned char reg, unsigned char value);
static unsigned char atari_scsi_falcon_reg_read(unsigned char reg);
static void atari_scsi_falcon_reg_write(unsigned char reg, unsigned char value);

/************************* End of Prototypes **************************/


static struct Scsi_Host *atari_scsi_host;
static unsigned char (*atari_scsi_reg_read)(unsigned char reg);
static void (*atari_scsi_reg_write)(unsigned char reg, unsigned char value);

#ifdef REAL_DMA
static unsigned long    atari_dma_residual, atari_dma_startaddr;
static short            atari_dma_active;
/* pointer to the dribble buffer */
static char       *atari_dma_buffer;
/* precalculated physical address of the dribble buffer */
static unsigned long    atari_dma_phys_buffer;
/* != 0 tells the Falcon int handler to copy data from the dribble buffer */
static char       *atari_dma_orig_addr;
/* size of the dribble buffer; 4k seems enough, since the Falcon cannot use
 * scatter-gather anyway, so most transfers are 1024 byte only. In the rare
 * cases where requests to physical contiguous buffers have been merged, this
 * request is <= 4k (one page). So I don't think we have to split transfers
 * just due to this buffer size...
 */
#define     STRAM_BUFFER_SIZE (4096)
/* mask for address bits that can't be used with the ST-DMA */
static unsigned long    atari_dma_stram_mask;
#define STRAM_ADDR(a)   (((a) & atari_dma_stram_mask) == 0)
/* number of bytes to cut from a transfer to handle NCR overruns */
static int atari_read_overruns;
#endif

static int setup_can_queue = -1;
module_param(setup_can_queue, int, 0);
static int setup_cmd_per_lun = -1;
module_param(setup_cmd_per_lun, int, 0);
static int setup_sg_tablesize = -1;
module_param(setup_sg_tablesize, int, 0);
#ifdef SUPPORT_TAGS
static int setup_use_tagged_queuing = -1;
module_param(setup_use_tagged_queuing, int, 0);
#endif
static int setup_hostid = -1;
module_param(setup_hostid, int, 0);


#if defined(CONFIG_TT_DMA_EMUL)
#include "atari_dma_emul.c"
#endif

#if defined(REAL_DMA)

static int scsi_dma_is_ignored_buserr(unsigned char dma_stat)
{
      int i;
      unsigned long addr = SCSI_DMA_READ_P(dma_addr), end_addr;

      if (dma_stat & 0x01) {

            /* A bus error happens when DMA-ing from the last page of a
             * physical memory chunk (DMA prefetch!), but that doesn't hurt.
             * Check for this case:
             */

            for (i = 0; i < m68k_num_memory; ++i) {
                  end_addr = m68k_memory[i].addr + m68k_memory[i].size;
                  if (end_addr <= addr && addr <= end_addr + 4)
                        return 1;
            }
      }
      return 0;
}


#if 0
/* Dead code... wasn't called anyway :-) and causes some trouble, because at
 * end-of-DMA, both SCSI ints are triggered simultaneously, so the NCR int has
 * to clear the DMA int pending bit before it allows other level 6 interrupts.
 */
static void scsi_dma_buserr(int irq, void *dummy)
{
      unsigned char dma_stat = tt_scsi_dma.dma_ctrl;

      /* Don't do anything if a NCR interrupt is pending. Probably it's just
       * masked... */
      if (atari_irq_pending(IRQ_TT_MFP_SCSI))
            return;

      printk("Bad SCSI DMA interrupt! dma_addr=0x%08lx dma_stat=%02x dma_cnt=%08lx\n",
             SCSI_DMA_READ_P(dma_addr), dma_stat, SCSI_DMA_READ_P(dma_cnt));
      if (dma_stat & 0x80) {
            if (!scsi_dma_is_ignored_buserr(dma_stat))
                  printk("SCSI DMA bus error -- bad DMA programming!\n");
      } else {
            /* Under normal circumstances we never should get to this point,
             * since both interrupts are triggered simultaneously and the 5380
             * int has higher priority. When this irq is handled, that DMA
             * interrupt is cleared. So a warning message is printed here.
             */
            printk("SCSI DMA intr ?? -- this shouldn't happen!\n");
      }
}
#endif

#endif


static irqreturn_t scsi_tt_intr(int irq, void *dummy)
{
#ifdef REAL_DMA
      int dma_stat;

      dma_stat = tt_scsi_dma.dma_ctrl;

      INT_PRINTK("scsi%d: NCR5380 interrupt, DMA status = %02x\n",
               atari_scsi_host->host_no, dma_stat & 0xff);

      /* Look if it was the DMA that has interrupted: First possibility
       * is that a bus error occurred...
       */
      if (dma_stat & 0x80) {
            if (!scsi_dma_is_ignored_buserr(dma_stat)) {
                  printk(KERN_ERR "SCSI DMA caused bus error near 0x%08lx\n",
                         SCSI_DMA_READ_P(dma_addr));
                  printk(KERN_CRIT "SCSI DMA bus error -- bad DMA programming!");
            }
      }

      /* If the DMA is active but not finished, we have the case
       * that some other 5380 interrupt occurred within the DMA transfer.
       * This means we have residual bytes, if the desired end address
       * is not yet reached. Maybe we have to fetch some bytes from the
       * rest data register, too. The residual must be calculated from
       * the address pointer, not the counter register, because only the
       * addr reg counts bytes not yet written and pending in the rest
       * data reg!
       */
      if ((dma_stat & 0x02) && !(dma_stat & 0x40)) {
            atari_dma_residual = HOSTDATA_DMALEN - (SCSI_DMA_READ_P(dma_addr) - atari_dma_startaddr);

            DMA_PRINTK("SCSI DMA: There are %ld residual bytes.\n",
                     atari_dma_residual);

            if ((signed int)atari_dma_residual < 0)
                  atari_dma_residual = 0;
            if ((dma_stat & 1) == 0) {
                  /*
                   * After read operations, we maybe have to
                   * transport some rest bytes
                   */
                  atari_scsi_fetch_restbytes();
            } else {
                  /*
                   * There seems to be a nasty bug in some SCSI-DMA/NCR
                   * combinations: If a target disconnects while a write
                   * operation is going on, the address register of the
                   * DMA may be a few bytes farer than it actually read.
                   * This is probably due to DMA prefetching and a delay
                   * between DMA and NCR.  Experiments showed that the
                   * dma_addr is 9 bytes to high, but this could vary.
                   * The problem is, that the residual is thus calculated
                   * wrong and the next transfer will start behind where
                   * it should.  So we round up the residual to the next
                   * multiple of a sector size, if it isn't already a
                   * multiple and the originally expected transfer size
                   * was.  The latter condition is there to ensure that
                   * the correction is taken only for "real" data
                   * transfers and not for, e.g., the parameters of some
                   * other command.  These shouldn't disconnect anyway.
                   */
                  if (atari_dma_residual & 0x1ff) {
                        DMA_PRINTK("SCSI DMA: DMA bug corrected, "
                                 "difference %ld bytes\n",
                                 512 - (atari_dma_residual & 0x1ff));
                        atari_dma_residual = (atari_dma_residual + 511) & ~0x1ff;
                  }
            }
            tt_scsi_dma.dma_ctrl = 0;
      }

      /* If the DMA is finished, fetch the rest bytes and turn it off */
      if (dma_stat & 0x40) {
            atari_dma_residual = 0;
            if ((dma_stat & 1) == 0)
                  atari_scsi_fetch_restbytes();
            tt_scsi_dma.dma_ctrl = 0;
      }

#endif /* REAL_DMA */

      NCR5380_intr(irq, dummy);

#if 0
      /* To be sure the int is not masked */
      atari_enable_irq(IRQ_TT_MFP_SCSI);
#endif
      return IRQ_HANDLED;
}


static irqreturn_t scsi_falcon_intr(int irq, void *dummy)
{
#ifdef REAL_DMA
      int dma_stat;

      /* Turn off DMA and select sector counter register before
       * accessing the status register (Atari recommendation!)
       */
      st_dma.dma_mode_status = 0x90;
      dma_stat = st_dma.dma_mode_status;

      /* Bit 0 indicates some error in the DMA process... don't know
       * what happened exactly (no further docu).
       */
      if (!(dma_stat & 0x01)) {
            /* DMA error */
            printk(KERN_CRIT "SCSI DMA error near 0x%08lx!\n", SCSI_DMA_GETADR());
      }

      /* If the DMA was active, but now bit 1 is not clear, it is some
       * other 5380 interrupt that finishes the DMA transfer. We have to
       * calculate the number of residual bytes and give a warning if
       * bytes are stuck in the ST-DMA fifo (there's no way to reach them!)
       */
      if (atari_dma_active && (dma_stat & 0x02)) {
            unsigned long transferred;

            transferred = SCSI_DMA_GETADR() - atari_dma_startaddr;
            /* The ST-DMA address is incremented in 2-byte steps, but the
             * data are written only in 16-byte chunks. If the number of
             * transferred bytes is not divisible by 16, the remainder is
             * lost somewhere in outer space.
             */
            if (transferred & 15)
                  printk(KERN_ERR "SCSI DMA error: %ld bytes lost in "
                         "ST-DMA fifo\n", transferred & 15);

            atari_dma_residual = HOSTDATA_DMALEN - transferred;
            DMA_PRINTK("SCSI DMA: There are %ld residual bytes.\n",
                     atari_dma_residual);
      } else
            atari_dma_residual = 0;
      atari_dma_active = 0;

      if (atari_dma_orig_addr) {
            /* If the dribble buffer was used on a read operation, copy the DMA-ed
             * data to the original destination address.
             */
            memcpy(atari_dma_orig_addr, phys_to_virt(atari_dma_startaddr),
                   HOSTDATA_DMALEN - atari_dma_residual);
            atari_dma_orig_addr = NULL;
      }

#endif /* REAL_DMA */

      NCR5380_intr(irq, dummy);
      return IRQ_HANDLED;
}


#ifdef REAL_DMA
static void atari_scsi_fetch_restbytes(void)
{
      int nr;
      char *src, *dst;
      unsigned long phys_dst;

      /* fetch rest bytes in the DMA register */
      phys_dst = SCSI_DMA_READ_P(dma_addr);
      nr = phys_dst & 3;
      if (nr) {
            /* there are 'nr' bytes left for the last long address
               before the DMA pointer */
            phys_dst ^= nr;
            DMA_PRINTK("SCSI DMA: there are %d rest bytes for phys addr 0x%08lx",
                     nr, phys_dst);
            /* The content of the DMA pointer is a physical address!  */
            dst = phys_to_virt(phys_dst);
            DMA_PRINTK(" = virt addr %p\n", dst);
            for (src = (char *)&tt_scsi_dma.dma_restdata; nr != 0; --nr)
                  *dst++ = *src++;
      }
}
#endif /* REAL_DMA */


static int falcon_got_lock = 0;
static DECLARE_WAIT_QUEUE_HEAD(falcon_fairness_wait);
static int falcon_trying_lock = 0;
static DECLARE_WAIT_QUEUE_HEAD(falcon_try_wait);
static int falcon_dont_release = 0;

/* This function releases the lock on the DMA chip if there is no
 * connected command and the disconnected queue is empty. On
 * releasing, instances of falcon_get_lock are awoken, that put
 * themselves to sleep for fairness. They can now try to get the lock
 * again (but others waiting longer more probably will win).
 */

static void falcon_release_lock_if_possible(struct NCR5380_hostdata *hostdata)
{
      unsigned long flags;

      if (IS_A_TT())
            return;

      local_irq_save(flags);

      if (falcon_got_lock && !hostdata->disconnected_queue &&
          !hostdata->issue_queue && !hostdata->connected) {

            if (falcon_dont_release) {
#if 0
                  printk("WARNING: Lock release not allowed. Ignored\n");
#endif
                  local_irq_restore(flags);
                  return;
            }
            falcon_got_lock = 0;
            stdma_release();
            wake_up(&falcon_fairness_wait);
      }

      local_irq_restore(flags);
}

/* This function manages the locking of the ST-DMA.
 * If the DMA isn't locked already for SCSI, it tries to lock it by
 * calling stdma_lock(). But if the DMA is locked by the SCSI code and
 * there are other drivers waiting for the chip, we do not issue the
 * command immediately but wait on 'falcon_fairness_queue'. We will be
 * waked up when the DMA is unlocked by some SCSI interrupt. After that
 * we try to get the lock again.
 * But we must be prepared that more than one instance of
 * falcon_get_lock() is waiting on the fairness queue. They should not
 * try all at once to call stdma_lock(), one is enough! For that, the
 * first one sets 'falcon_trying_lock', others that see that variable
 * set wait on the queue 'falcon_try_wait'.
 * Complicated, complicated.... Sigh...
 */

static void falcon_get_lock(void)
{
      unsigned long flags;

      if (IS_A_TT())
            return;

      local_irq_save(flags);

      while (!in_irq() && falcon_got_lock && stdma_others_waiting())
            sleep_on(&falcon_fairness_wait);

      while (!falcon_got_lock) {
            if (in_irq())
                  panic("Falcon SCSI hasn't ST-DMA lock in interrupt");
            if (!falcon_trying_lock) {
                  falcon_trying_lock = 1;
                  stdma_lock(scsi_falcon_intr, NULL);
                  falcon_got_lock = 1;
                  falcon_trying_lock = 0;
                  wake_up(&falcon_try_wait);
            } else {
                  sleep_on(&falcon_try_wait);
            }
      }

      local_irq_restore(flags);
      if (!falcon_got_lock)
            panic("Falcon SCSI: someone stole the lock :-(\n");
}


/* This is the wrapper function for NCR5380_queue_command(). It just
 * tries to get the lock on the ST-DMA (see above) and then calls the
 * original function.
 */

#if 0
int atari_queue_command(Scsi_Cmnd *cmd, void (*done)(Scsi_Cmnd *))
{
      /* falcon_get_lock();
       * ++guenther: moved to NCR5380_queue_command() to prevent
       * race condition, see there for an explanation.
       */
      return NCR5380_queue_command(cmd, done);
}
#endif


int atari_scsi_detect(struct scsi_host_template *host)
{
      static int called = 0;
      struct Scsi_Host *instance;

      if (!MACH_IS_ATARI ||
          (!ATARIHW_PRESENT(ST_SCSI) && !ATARIHW_PRESENT(TT_SCSI)) ||
          called)
            return 0;

      host->proc_name = "Atari";

      atari_scsi_reg_read  = IS_A_TT() ? atari_scsi_tt_reg_read :
                                 atari_scsi_falcon_reg_read;
      atari_scsi_reg_write = IS_A_TT() ? atari_scsi_tt_reg_write :
                                 atari_scsi_falcon_reg_write;

      /* setup variables */
      host->can_queue =
            (setup_can_queue > 0) ? setup_can_queue :
            IS_A_TT() ? ATARI_TT_CAN_QUEUE : ATARI_FALCON_CAN_QUEUE;
      host->cmd_per_lun =
            (setup_cmd_per_lun > 0) ? setup_cmd_per_lun :
            IS_A_TT() ? ATARI_TT_CMD_PER_LUN : ATARI_FALCON_CMD_PER_LUN;
      /* Force sg_tablesize to 0 on a Falcon! */
      host->sg_tablesize =
            !IS_A_TT() ? ATARI_FALCON_SG_TABLESIZE :
            (setup_sg_tablesize >= 0) ? setup_sg_tablesize : ATARI_TT_SG_TABLESIZE;

      if (setup_hostid >= 0)
            host->this_id = setup_hostid;
      else {
            /* use 7 as default */
            host->this_id = 7;
            /* Test if a host id is set in the NVRam */
            if (ATARIHW_PRESENT(TT_CLK) && nvram_check_checksum()) {
                  unsigned char b = nvram_read_byte( 14 );
                  /* Arbitration enabled? (for TOS) If yes, use configured host ID */
                  if (b & 0x80)
                        host->this_id = b & 7;
            }
      }

#ifdef SUPPORT_TAGS
      if (setup_use_tagged_queuing < 0)
            setup_use_tagged_queuing = DEFAULT_USE_TAGGED_QUEUING;
#endif
#ifdef REAL_DMA
      /* If running on a Falcon and if there's TT-Ram (i.e., more than one
       * memory block, since there's always ST-Ram in a Falcon), then allocate a
       * STRAM_BUFFER_SIZE byte dribble buffer for transfers from/to alternative
       * Ram.
       */
      if (MACH_IS_ATARI && ATARIHW_PRESENT(ST_SCSI) &&
          !ATARIHW_PRESENT(EXTD_DMA) && m68k_num_memory > 1) {
            atari_dma_buffer = atari_stram_alloc(STRAM_BUFFER_SIZE, "SCSI");
            if (!atari_dma_buffer) {
                  printk(KERN_ERR "atari_scsi_detect: can't allocate ST-RAM "
                              "double buffer\n");
                  return 0;
            }
            atari_dma_phys_buffer = virt_to_phys(atari_dma_buffer);
            atari_dma_orig_addr = 0;
      }
#endif
      instance = scsi_register(host, sizeof(struct NCR5380_hostdata));
      if (instance == NULL) {
            atari_stram_free(atari_dma_buffer);
            atari_dma_buffer = 0;
            return 0;
      }
      atari_scsi_host = instance;
      /*
       * Set irq to 0, to avoid that the mid-level code disables our interrupt
       * during queue_command calls. This is completely unnecessary, and even
       * worse causes bad problems on the Falcon, where the int is shared with
       * IDE and floppy!
       */
       instance->irq = 0;

#ifdef CONFIG_ATARI_SCSI_RESET_BOOT
      atari_scsi_reset_boot();
#endif
      NCR5380_init(instance, 0);

      if (IS_A_TT()) {

            /* This int is actually "pseudo-slow", i.e. it acts like a slow
             * interrupt after having cleared the pending flag for the DMA
             * interrupt. */
            if (request_irq(IRQ_TT_MFP_SCSI, scsi_tt_intr, IRQ_TYPE_SLOW,
                         "SCSI NCR5380", instance)) {
                  printk(KERN_ERR "atari_scsi_detect: cannot allocate irq %d, aborting",IRQ_TT_MFP_SCSI);
                  scsi_unregister(atari_scsi_host);
                  atari_stram_free(atari_dma_buffer);
                  atari_dma_buffer = 0;
                  return 0;
            }
            tt_mfp.active_edge |= 0x80;         /* SCSI int on L->H */
#ifdef REAL_DMA
            tt_scsi_dma.dma_ctrl = 0;
            atari_dma_residual = 0;
#ifdef CONFIG_TT_DMA_EMUL
            if (MACH_IS_HADES) {
                  if (request_irq(IRQ_AUTO_2, hades_dma_emulator,
                               IRQ_TYPE_PRIO, "Hades DMA emulator",
                               hades_dma_emulator)) {
                        printk(KERN_ERR "atari_scsi_detect: cannot allocate irq %d, aborting (MACH_IS_HADES)",IRQ_AUTO_2);
                        free_irq(IRQ_TT_MFP_SCSI, instance);
                        scsi_unregister(atari_scsi_host);
                        atari_stram_free(atari_dma_buffer);
                        atari_dma_buffer = 0;
                        return 0;
                  }
            }
#endif
            if (MACH_IS_MEDUSA || MACH_IS_HADES) {
                  /* While the read overruns (described by Drew Eckhardt in
                   * NCR5380.c) never happened on TTs, they do in fact on the Medusa
                   * (This was the cause why SCSI didn't work right for so long
                   * there.) Since handling the overruns slows down a bit, I turned
                   * the #ifdef's into a runtime condition.
                   *
                   * In principle it should be sufficient to do max. 1 byte with
                   * PIO, but there is another problem on the Medusa with the DMA
                   * rest data register. So 'atari_read_overruns' is currently set
                   * to 4 to avoid having transfers that aren't a multiple of 4. If
                   * the rest data bug is fixed, this can be lowered to 1.
                   */
                  atari_read_overruns = 4;
            }
#endif /*REAL_DMA*/
      } else { /* ! IS_A_TT */

            /* Nothing to do for the interrupt: the ST-DMA is initialized
             * already by atari_init_INTS()
             */

#ifdef REAL_DMA
            atari_dma_residual = 0;
            atari_dma_active = 0;
            atari_dma_stram_mask = (ATARIHW_PRESENT(EXTD_DMA) ? 0x00000000
                              : 0xff000000);
#endif
      }

      printk(KERN_INFO "scsi%d: options CAN_QUEUE=%d CMD_PER_LUN=%d SCAT-GAT=%d "
#ifdef SUPPORT_TAGS
                  "TAGGED-QUEUING=%s "
#endif
                  "HOSTID=%d",
                  instance->host_no, instance->hostt->can_queue,
                  instance->hostt->cmd_per_lun,
                  instance->hostt->sg_tablesize,
#ifdef SUPPORT_TAGS
                  setup_use_tagged_queuing ? "yes" : "no",
#endif
                  instance->hostt->this_id );
      NCR5380_print_options(instance);
      printk("\n");

      called = 1;
      return 1;
}

int atari_scsi_release(struct Scsi_Host *sh)
{
      if (IS_A_TT())
            free_irq(IRQ_TT_MFP_SCSI, sh);
      if (atari_dma_buffer)
            atari_stram_free(atari_dma_buffer);
      return 1;
}

void __init atari_scsi_setup(char *str, int *ints)
{
      /* Format of atascsi parameter is:
       *   atascsi=<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
       * Defaults depend on TT or Falcon, hostid determined at run time.
       * Negative values mean don't change.
       */

      if (ints[0] < 1) {
            printk("atari_scsi_setup: no arguments!\n");
            return;
      }

      if (ints[0] >= 1) {
            if (ints[1] > 0)
                  /* no limits on this, just > 0 */
                  setup_can_queue = ints[1];
      }
      if (ints[0] >= 2) {
            if (ints[2] > 0)
                  setup_cmd_per_lun = ints[2];
      }
      if (ints[0] >= 3) {
            if (ints[3] >= 0) {
                  setup_sg_tablesize = ints[3];
                  /* Must be <= SG_ALL (255) */
                  if (setup_sg_tablesize > SG_ALL)
                        setup_sg_tablesize = SG_ALL;
            }
      }
      if (ints[0] >= 4) {
            /* Must be between 0 and 7 */
            if (ints[4] >= 0 && ints[4] <= 7)
                  setup_hostid = ints[4];
            else if (ints[4] > 7)
                  printk("atari_scsi_setup: invalid host ID %d !\n", ints[4]);
      }
#ifdef SUPPORT_TAGS
      if (ints[0] >= 5) {
            if (ints[5] >= 0)
                  setup_use_tagged_queuing = !!ints[5];
      }
#endif
}

int atari_scsi_bus_reset(Scsi_Cmnd *cmd)
{
      int rv;
      struct NCR5380_hostdata *hostdata =
            (struct NCR5380_hostdata *)cmd->device->host->hostdata;

      /* For doing the reset, SCSI interrupts must be disabled first,
       * since the 5380 raises its IRQ line while _RST is active and we
       * can't disable interrupts completely, since we need the timer.
       */
      /* And abort a maybe active DMA transfer */
      if (IS_A_TT()) {
            atari_turnoff_irq(IRQ_TT_MFP_SCSI);
#ifdef REAL_DMA
            tt_scsi_dma.dma_ctrl = 0;
#endif /* REAL_DMA */
      } else {
            atari_turnoff_irq(IRQ_MFP_FSCSI);
#ifdef REAL_DMA
            st_dma.dma_mode_status = 0x90;
            atari_dma_active = 0;
            atari_dma_orig_addr = NULL;
#endif /* REAL_DMA */
      }

      rv = NCR5380_bus_reset(cmd);

      /* Re-enable ints */
      if (IS_A_TT()) {
            atari_turnon_irq(IRQ_TT_MFP_SCSI);
      } else {
            atari_turnon_irq(IRQ_MFP_FSCSI);
      }
      if ((rv & SCSI_RESET_ACTION) == SCSI_RESET_SUCCESS)
            falcon_release_lock_if_possible(hostdata);

      return rv;
}


#ifdef CONFIG_ATARI_SCSI_RESET_BOOT
static void __init atari_scsi_reset_boot(void)
{
      unsigned long end;

      /*
       * Do a SCSI reset to clean up the bus during initialization. No messing
       * with the queues, interrupts, or locks necessary here.
       */

      printk("Atari SCSI: resetting the SCSI bus...");

      /* get in phase */
      NCR5380_write(TARGET_COMMAND_REG,
                  PHASE_SR_TO_TCR(NCR5380_read(STATUS_REG)));

      /* assert RST */
      NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_RST);
      /* The min. reset hold time is 25us, so 40us should be enough */
      udelay(50);
      /* reset RST and interrupt */
      NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
      NCR5380_read(RESET_PARITY_INTERRUPT_REG);

      end = jiffies + AFTER_RESET_DELAY;
      while (time_before(jiffies, end))
            barrier();

      printk(" done\n");
}
#endif


const char *atari_scsi_info(struct Scsi_Host *host)
{
      /* atari_scsi_detect() is verbose enough... */
      static const char string[] = "Atari native SCSI";
      return string;
}


#if defined(REAL_DMA)

unsigned long atari_scsi_dma_setup(struct Scsi_Host *instance, void *data,
                           unsigned long count, int dir)
{
      unsigned long addr = virt_to_phys(data);

      DMA_PRINTK("scsi%d: setting up dma, data = %p, phys = %lx, count = %ld, "
               "dir = %d\n", instance->host_no, data, addr, count, dir);

      if (!IS_A_TT() && !STRAM_ADDR(addr)) {
            /* If we have a non-DMAable address on a Falcon, use the dribble
             * buffer; 'orig_addr' != 0 in the read case tells the interrupt
             * handler to copy data from the dribble buffer to the originally
             * wanted address.
             */
            if (dir)
                  memcpy(atari_dma_buffer, data, count);
            else
                  atari_dma_orig_addr = data;
            addr = atari_dma_phys_buffer;
      }

      atari_dma_startaddr = addr;   /* Needed for calculating residual later. */

      /* Cache cleanup stuff: On writes, push any dirty cache out before sending
       * it to the peripheral. (Must be done before DMA setup, since at least
       * the ST-DMA begins to fill internal buffers right after setup. For
       * reads, invalidate any cache, may be altered after DMA without CPU
       * knowledge.
       *
       * ++roman: For the Medusa, there's no need at all for that cache stuff,
       * because the hardware does bus snooping (fine!).
       */
      dma_cache_maintenance(addr, count, dir);

      if (count == 0)
            printk(KERN_NOTICE "SCSI warning: DMA programmed for 0 bytes !\n");

      if (IS_A_TT()) {
            tt_scsi_dma.dma_ctrl = dir;
            SCSI_DMA_WRITE_P(dma_addr, addr);
            SCSI_DMA_WRITE_P(dma_cnt, count);
            tt_scsi_dma.dma_ctrl = dir | 2;
      } else { /* ! IS_A_TT */

            /* set address */
            SCSI_DMA_SETADR(addr);

            /* toggle direction bit to clear FIFO and set DMA direction */
            dir <<= 8;
            st_dma.dma_mode_status = 0x90 | dir;
            st_dma.dma_mode_status = 0x90 | (dir ^ 0x100);
            st_dma.dma_mode_status = 0x90 | dir;
            udelay(40);
            /* On writes, round up the transfer length to the next multiple of 512
             * (see also comment at atari_dma_xfer_len()). */
            st_dma.fdc_acces_seccount = (count + (dir ? 511 : 0)) >> 9;
            udelay(40);
            st_dma.dma_mode_status = 0x10 | dir;
            udelay(40);
            /* need not restore value of dir, only boolean value is tested */
            atari_dma_active = 1;
      }

      return count;
}


static long atari_scsi_dma_residual(struct Scsi_Host *instance)
{
      return atari_dma_residual;
}


#define     CMD_SURELY_BLOCK_MODE   0
#define     CMD_SURELY_BYTE_MODE    1
#define     CMD_MODE_UNKNOWN        2

static int falcon_classify_cmd(Scsi_Cmnd *cmd)
{
      unsigned char opcode = cmd->cmnd[0];

      if (opcode == READ_DEFECT_DATA || opcode == READ_LONG ||
          opcode == READ_BUFFER)
            return CMD_SURELY_BYTE_MODE;
      else if (opcode == READ_6 || opcode == READ_10 ||
             opcode == 0xa8 /* READ_12 */ || opcode == READ_REVERSE ||
             opcode == RECOVER_BUFFERED_DATA) {
            /* In case of a sequential-access target (tape), special care is
             * needed here: The transfer is block-mode only if the 'fixed' bit is
             * set! */
            if (cmd->device->type == TYPE_TAPE && !(cmd->cmnd[1] & 1))
                  return CMD_SURELY_BYTE_MODE;
            else
                  return CMD_SURELY_BLOCK_MODE;
      } else
            return CMD_MODE_UNKNOWN;
}


/* This function calculates the number of bytes that can be transferred via
 * DMA. On the TT, this is arbitrary, but on the Falcon we have to use the
 * ST-DMA chip. There are only multiples of 512 bytes possible and max.
 * 255*512 bytes :-( This means also, that defining READ_OVERRUNS is not
 * possible on the Falcon, since that would require to program the DMA for
 * n*512 - atari_read_overrun bytes. But it seems that the Falcon doesn't have
 * the overrun problem, so this question is academic :-)
 */

static unsigned long atari_dma_xfer_len(unsigned long wanted_len,
                              Scsi_Cmnd *cmd, int write_flag)
{
      unsigned long     possible_len, limit;
#ifndef CONFIG_TT_DMA_EMUL
      if (MACH_IS_HADES)
            /* Hades has no SCSI DMA at all :-( Always force use of PIO */
            return 0;
#endif
      if (IS_A_TT())
            /* TT SCSI DMA can transfer arbitrary #bytes */
            return wanted_len;

      /* ST DMA chip is stupid -- only multiples of 512 bytes! (and max.
       * 255*512 bytes, but this should be enough)
       *
       * ++roman: Aaargl! Another Falcon-SCSI problem... There are some commands
       * that return a number of bytes which cannot be known beforehand. In this
       * case, the given transfer length is an "allocation length". Now it
       * can happen that this allocation length is a multiple of 512 bytes and
       * the DMA is used. But if not n*512 bytes really arrive, some input data
       * will be lost in the ST-DMA's FIFO :-( Thus, we have to distinguish
       * between commands that do block transfers and those that do byte
       * transfers. But this isn't easy... there are lots of vendor specific
       * commands, and the user can issue any command via the
       * SCSI_IOCTL_SEND_COMMAND.
       *
       * The solution: We classify SCSI commands in 1) surely block-mode cmd.s,
       * 2) surely byte-mode cmd.s and 3) cmd.s with unknown mode. In case 1)
       * and 3), the thing to do is obvious: allow any number of blocks via DMA
       * or none. In case 2), we apply some heuristic: Byte mode is assumed if
       * the transfer (allocation) length is < 1024, hoping that no cmd. not
       * explicitly known as byte mode have such big allocation lengths...
       * BTW, all the discussion above applies only to reads. DMA writes are
       * unproblematic anyways, since the targets aborts the transfer after
       * receiving a sufficient number of bytes.
       *
       * Another point: If the transfer is from/to an non-ST-RAM address, we
       * use the dribble buffer and thus can do only STRAM_BUFFER_SIZE bytes.
       */

      if (write_flag) {
            /* Write operation can always use the DMA, but the transfer size must
             * be rounded up to the next multiple of 512 (atari_dma_setup() does
             * this).
             */
            possible_len = wanted_len;
      } else {
            /* Read operations: if the wanted transfer length is not a multiple of
             * 512, we cannot use DMA, since the ST-DMA cannot split transfers
             * (no interrupt on DMA finished!)
             */
            if (wanted_len & 0x1ff)
                  possible_len = 0;
            else {
                  /* Now classify the command (see above) and decide whether it is
                   * allowed to do DMA at all */
                  switch (falcon_classify_cmd(cmd)) {
                  case CMD_SURELY_BLOCK_MODE:
                        possible_len = wanted_len;
                        break;
                  case CMD_SURELY_BYTE_MODE:
                        possible_len = 0; /* DMA prohibited */
                        break;
                  case CMD_MODE_UNKNOWN:
                  default:
                        /* For unknown commands assume block transfers if the transfer
                         * size/allocation length is >= 1024 */
                        possible_len = (wanted_len < 1024) ? 0 : wanted_len;
                        break;
                  }
            }
      }

      /* Last step: apply the hard limit on DMA transfers */
      limit = (atari_dma_buffer && !STRAM_ADDR(virt_to_phys(cmd->SCp.ptr))) ?
                STRAM_BUFFER_SIZE : 255*512;
      if (possible_len > limit)
            possible_len = limit;

      if (possible_len != wanted_len)
            DMA_PRINTK("Sorry, must cut DMA transfer size to %ld bytes "
                     "instead of %ld\n", possible_len, wanted_len);

      return possible_len;
}


#endif      /* REAL_DMA */


/* NCR5380 register access functions
 *
 * There are separate functions for TT and Falcon, because the access
 * methods are quite different. The calling macros NCR5380_read and
 * NCR5380_write call these functions via function pointers.
 */

static unsigned char atari_scsi_tt_reg_read(unsigned char reg)
{
      return tt_scsi_regp[reg * 2];
}

static void atari_scsi_tt_reg_write(unsigned char reg, unsigned char value)
{
      tt_scsi_regp[reg * 2] = value;
}

static unsigned char atari_scsi_falcon_reg_read(unsigned char reg)
{
      dma_wd.dma_mode_status= (u_short)(0x88 + reg);
      return (u_char)dma_wd.fdc_acces_seccount;
}

static void atari_scsi_falcon_reg_write(unsigned char reg, unsigned char value)
{
      dma_wd.dma_mode_status = (u_short)(0x88 + reg);
      dma_wd.fdc_acces_seccount = (u_short)value;
}


#include "atari_NCR5380.c"

static struct scsi_host_template driver_template = {
      .proc_info        = atari_scsi_proc_info,
      .name             = "Atari native SCSI",
      .detect                 = atari_scsi_detect,
      .release          = atari_scsi_release,
      .info             = atari_scsi_info,
      .queuecommand           = atari_scsi_queue_command,
      .eh_abort_handler = atari_scsi_abort,
      .eh_bus_reset_handler   = atari_scsi_bus_reset,
      .can_queue        = 0, /* initialized at run-time */
      .this_id          = 0, /* initialized at run-time */
      .sg_tablesize           = 0, /* initialized at run-time */
      .cmd_per_lun            = 0, /* initialized at run-time */
      .use_clustering         = DISABLE_CLUSTERING
};


#include "scsi_module.c"

MODULE_LICENSE("GPL");

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