Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1163 insertions, 0 deletions

diff --git a/drivers/scsi/atari_scsi.c b/drivers/scsi/atari_scsi.c
new file mode 100644
index 000000000000..af8adb629b33
--- /dev/null
+++ b/drivers/scsi/atari_scsi.c
@@ -0,0 +1,1163 @@
+/*
+ * 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/config.h>
+#include <linux/module.h>
+
+#define NDEBUG (0)
+
+#define NDEBUG_ABORT    0x800000
+#define NDEBUG_TAGS     0x1000000
+#define NDEBUG_MERGING  0x2000000
+
+#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/sched.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, struct pt_regs *fp);
+static irqreturn_t scsi_falcon_intr( int irq, void *dummy, struct pt_regs *fp);
+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 = NULL;
+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 = NULL;
+/* 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 = 0;
+#endif
+
+static int setup_can_queue = -1;
+MODULE_PARM(setup_can_queue, "i");
+static int setup_cmd_per_lun = -1;
+MODULE_PARM(setup_cmd_per_lun, "i");
+static int setup_sg_tablesize = -1;
+MODULE_PARM(setup_sg_tablesize, "i");
+#ifdef SUPPORT_TAGS
+static int setup_use_tagged_queuing = -1;
+MODULE_PARM(setup_use_tagged_queuing, "i");
+#endif
+static int setup_hostid = -1;
+MODULE_PARM(setup_hostid, "i");
+
+
+#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, struct pt_regs *fp)
+{
+        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, struct pt_regs *fp)
+{
+#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 (0, 0, 0);
+
+#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, struct pt_regs *fp)
+{
+#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 (0, 0, 0);
+        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_interrupt() && falcon_got_lock && stdma_others_waiting() )
+                sleep_on( &falcon_fairness_wait );
+
+        while (!falcon_got_lock) {
+                if (in_interrupt())
+                        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 (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", scsi_tt_intr)) {
+                        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, scsi_tt_intr);
+                                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 );
+}
+
+#ifdef MODULE
+int atari_scsi_release (struct Scsi_Host *sh)
+{
+        if (IS_A_TT())
+                free_irq(IRQ_TT_MFP_SCSI, scsi_tt_intr);
+        if (atari_dma_buffer)
+                atari_stram_free (atari_dma_buffer);
+        return 1;
+}
+#endif
+
+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 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");