[TG3]: Set minimal hw interrupt mitigation.

[linux-2.6/verdex.git] / drivers / char / ftape / lowlevel / ftape-io.c

/*
 *      Copyright (C) 1993-1996 Bas Laarhoven,
 *                (C) 1996      Kai Harrekilde-Petersen,
 *                (C) 1997      Claus-Justus Heine.

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2, or (at your option)
 any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; see the file COPYING.  If not, write to
 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

 *
 * $Source: /homes/cvs/ftape-stacked/ftape/lowlevel/ftape-io.c,v $
 * $Revision: 1.4 $
 * $Date: 1997/11/11 14:02:36 $
 *
 *      This file contains the general control functions for the
 *      QIC-40/80/3010/3020 floppy-tape driver "ftape" for Linux.
 */

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <asm/system.h>
#include <linux/ioctl.h>
#include <linux/mtio.h>
#include <linux/delay.h>

#include <linux/ftape.h>
#include <linux/qic117.h>
#include "../lowlevel/ftape-tracing.h"
#include "../lowlevel/fdc-io.h"
#include "../lowlevel/ftape-io.h"
#include "../lowlevel/ftape-ctl.h"
#include "../lowlevel/ftape-rw.h"
#include "../lowlevel/ftape-write.h"
#include "../lowlevel/ftape-read.h"
#include "../lowlevel/ftape-init.h"
#include "../lowlevel/ftape-calibr.h"

/*      Global vars.
 */
/* NOTE: sectors start numbering at 1, all others at 0 ! */
ft_timeout_table ftape_timeout;
unsigned int ftape_tape_len;
volatile qic117_cmd_t ftape_current_command;
const struct qic117_command_table qic117_cmds[] = QIC117_COMMANDS;
int ftape_might_be_off_track;

/*      Local vars.
 */
static int diagnostic_mode;
static unsigned int ftape_udelay_count;
static unsigned int ftape_udelay_time;

void ftape_udelay(unsigned int usecs)
{
        volatile int count = (ftape_udelay_count * usecs +
                              ftape_udelay_count - 1) / ftape_udelay_time;
        volatile int i;

        while (count-- > 0) {
                for (i = 0; i < 20; ++i);
        }
}

void ftape_udelay_calibrate(void)
{
        ftape_calibrate("ftape_udelay",
                        ftape_udelay, &ftape_udelay_count, &ftape_udelay_time);
}

/*      Delay (msec) routine.
 */
void ftape_sleep(unsigned int time)
{
        TRACE_FUN(ft_t_any);

        time *= 1000;   /* msecs -> usecs */
        if (time < FT_USPT) {
                /*  Time too small for scheduler, do a busy wait ! */
                ftape_udelay(time);
        } else {
                long timeout;
                unsigned long flags;
                unsigned int ticks = (time + FT_USPT - 1) / FT_USPT;

                TRACE(ft_t_any, "%d msec, %d ticks", time/1000, ticks);
                timeout = ticks;
                save_flags(flags);
                sti();
                msleep_interruptible(jiffies_to_msecs(timeout));
                /*  Mmm. Isn't current->blocked == 0xffffffff ?
                 */
                if (signal_pending(current)) {
                        TRACE(ft_t_err, "awoken by non-blocked signal :-(");
                }
                restore_flags(flags);
        }
        TRACE_EXIT;
}

/*  send a command or parameter to the drive
 *  Generates # of step pulses.
 */
static inline int ft_send_to_drive(int arg)
{
        /*  Always wait for a command_timeout period to separate
         *  individuals commands and/or parameters.
         */
        ftape_sleep(3 * FT_MILLISECOND);
        /*  Keep cylinder nr within range, step towards home if possible.
         */
        if (ftape_current_cylinder >= arg) {
                return fdc_seek(ftape_current_cylinder - arg);
        } else {
                return fdc_seek(ftape_current_cylinder + arg);
        }
}

/* forward */ int ftape_report_raw_drive_status(int *status);

static int ft_check_cmd_restrictions(qic117_cmd_t command)
{
        int status = -1;
        TRACE_FUN(ft_t_any);
        
        TRACE(ft_t_flow, "%s", qic117_cmds[command].name);
        /* A new motion command during an uninterruptible (motion)
         *  command requires a ready status before the new command can
         *  be issued. Otherwise a new motion command needs to be
         *  checked against required status.
         */
        if (qic117_cmds[command].cmd_type == motion &&
            qic117_cmds[ftape_current_command].non_intr) {
                ftape_report_raw_drive_status(&status);
                if ((status & QIC_STATUS_READY) == 0) {
                        TRACE(ft_t_noise,
                              "motion cmd (%d) during non-intr cmd (%d)",
                              command, ftape_current_command);
                        TRACE(ft_t_noise, "waiting until drive gets ready");
                        ftape_ready_wait(ftape_timeout.seek,
                                         &status);
                }
        }
        if (qic117_cmds[command].mask != 0) {
                __u8 difference;
                /*  Some commands do require a certain status:
                 */
                if (status == -1) {     /* not yet set */
                        ftape_report_raw_drive_status(&status);
                }
                difference = ((status ^ qic117_cmds[command].state) &
                              qic117_cmds[command].mask);
                /*  Wait until the drive gets
                 *  ready. This may last forever if
                 *  the drive never gets ready... 
                 */
                while ((difference & QIC_STATUS_READY) != 0) {
                        TRACE(ft_t_noise, "command %d issued while not ready",
                              command);
                        TRACE(ft_t_noise, "waiting until drive gets ready");
                        if (ftape_ready_wait(ftape_timeout.seek,
                                             &status) == -EINTR) {
                                /*  Bail out on signal !
                                 */
                                TRACE_ABORT(-EINTR, ft_t_warn,
                                      "interrupted by non-blockable signal");
                        }
                        difference = ((status ^ qic117_cmds[command].state) &
                                      qic117_cmds[command].mask);
                }
                while ((difference & QIC_STATUS_ERROR) != 0) {
                        int err;
                        qic117_cmd_t cmd;

                        TRACE(ft_t_noise,
                              "command %d issued while error pending",
                              command);
                        TRACE(ft_t_noise, "clearing error status");
                        ftape_report_error(&err, &cmd, 1);
                        ftape_report_raw_drive_status(&status);
                        difference = ((status ^ qic117_cmds[command].state) &
                                      qic117_cmds[command].mask);
                        if ((difference & QIC_STATUS_ERROR) != 0) {
                                /*  Bail out on fatal signal !
                                 */
                                FT_SIGNAL_EXIT(_NEVER_BLOCK);
                        }
                }
                if (difference) {
                        /*  Any remaining difference can't be solved
                         *  here.  
                         */
                        if (difference & (QIC_STATUS_CARTRIDGE_PRESENT |
                                          QIC_STATUS_NEW_CARTRIDGE |
                                          QIC_STATUS_REFERENCED)) {
                                TRACE(ft_t_warn,
                                      "Fatal: tape removed or reinserted !");
                                ft_failure = 1;
                        } else {
                                TRACE(ft_t_err, "wrong state: 0x%02x should be: 0x%02x",
                                      status & qic117_cmds[command].mask,
                                      qic117_cmds[command].state);
                        }
                        TRACE_EXIT -EIO;
                }
                if (~status & QIC_STATUS_READY & qic117_cmds[command].mask) {
                        TRACE_ABORT(-EBUSY, ft_t_err, "Bad: still busy!");
                }
        }
        TRACE_EXIT 0;
}

/*      Issue a tape command:
 */
int ftape_command(qic117_cmd_t command)
{
        int result = 0;
        static int level;
        TRACE_FUN(ft_t_any);

        if ((unsigned int)command > NR_ITEMS(qic117_cmds)) {
                /*  This is a bug we'll want to know about too.
                 */
                TRACE_ABORT(-EIO, ft_t_bug, "bug - bad command: %d", command);
        }
        if (++level > 5) { /*  This is a bug we'll want to know about. */
                --level;
                TRACE_ABORT(-EIO, ft_t_bug, "bug - recursion for command: %d",
                            command);
        }
        /*  disable logging and restriction check for some commands,
         *  check all other commands that have a prescribed starting
         *  status.
         */
        if (diagnostic_mode) {
                TRACE(ft_t_flow, "diagnostic command %d", command);
        } else if (command == QIC_REPORT_DRIVE_STATUS ||
                   command == QIC_REPORT_NEXT_BIT) {
                TRACE(ft_t_any, "%s", qic117_cmds[command].name);
        } else {
                TRACE_CATCH(ft_check_cmd_restrictions(command), --level);
        }
        /*  Now all conditions are met or result was < 0.
         */
        result = ft_send_to_drive((unsigned int)command);
        if (qic117_cmds[command].cmd_type == motion &&
            command != QIC_LOGICAL_FORWARD && command != QIC_STOP_TAPE) {
                ft_location.known = 0;
        }
        ftape_current_command = command;
        --level;
        TRACE_EXIT result;
}

/*      Send a tape command parameter:
 *      Generates command # of step pulses.
 *      Skips tape-status call !
 */
int ftape_parameter(unsigned int parameter)
{
        TRACE_FUN(ft_t_any);

        TRACE(ft_t_flow, "called with parameter = %d", parameter);
        TRACE_EXIT ft_send_to_drive(parameter + 2);
}

/*      Wait for the drive to get ready.
 *      timeout time in milli-seconds
 *      Returned status is valid if result != -EIO
 *
 *      Should we allow to be killed by SIGINT?  (^C)
 *      Would be nice at least for large timeouts.
 */
int ftape_ready_wait(unsigned int timeout, int *status)
{
        unsigned long t0;
        unsigned int poll_delay;
        int signal_retries;
        TRACE_FUN(ft_t_any);

        /*  the following ** REALLY ** reduces the system load when
         *  e.g. one simply rewinds or retensions. The tape is slow 
         *  anyway. It is really not necessary to detect error 
         *  conditions with 1/10 seconds granularity
         *
         *  On my AMD 133MHZ 486: 100 ms: 23% system load
         *                        1  sec:  5%
         *                        5  sec:  0.6%, yeah
         */
        if (timeout <= FT_SECOND) {
                poll_delay = 100 * FT_MILLISECOND;
                signal_retries = 20; /* two seconds */
        } else if (timeout < 20 * FT_SECOND) {
                TRACE(ft_t_flow, "setting poll delay to 1 second");
                poll_delay = FT_SECOND;
                signal_retries = 2; /* two seconds */
        } else {
                TRACE(ft_t_flow, "setting poll delay to 5 seconds");
                poll_delay = 5 * FT_SECOND;
                signal_retries = 1; /* five seconds */
        }
        for (;;) {
                t0 = jiffies;
                TRACE_CATCH(ftape_report_raw_drive_status(status),);
                if (*status & QIC_STATUS_READY) {
                        TRACE_EXIT 0;
                }
                if (!signal_retries--) {
                        FT_SIGNAL_EXIT(_NEVER_BLOCK);
                }
                if ((int)timeout >= 0) {
                        /* this will fail when jiffies wraps around about
                         * once every year :-)
                         */
                        timeout -= ((jiffies - t0) * FT_SECOND) / HZ;
                        if (timeout <= 0) {
                                TRACE_ABORT(-ETIME, ft_t_err, "timeout");
                        }
                        ftape_sleep(poll_delay);
                        timeout -= poll_delay;
                } else {
                        ftape_sleep(poll_delay);
                }
        }
        TRACE_EXIT -ETIME;
}

/*      Issue command and wait up to timeout milli seconds for drive ready
 */
int ftape_command_wait(qic117_cmd_t command, unsigned int timeout, int *status)
{
        int result;

        /* Drive should be ready, issue command
         */
        result = ftape_command(command);
        if (result >= 0) {
                result = ftape_ready_wait(timeout, status);
        }
        return result;
}

static int ftape_parameter_wait(unsigned int parm, unsigned int timeout, int *status)
{
        int result;

        /* Drive should be ready, issue command
         */
        result = ftape_parameter(parm);
        if (result >= 0) {
                result = ftape_ready_wait(timeout, status);
        }
        return result;
}

/*--------------------------------------------------------------------------
 *      Report operations
 */

/* Query the drive about its status.  The command is sent and
   result_length bits of status are returned (2 extra bits are read
   for start and stop). */

int ftape_report_operation(int *status,
                           qic117_cmd_t command,
                           int result_length)
{
        int i, st3;
        unsigned int t0;
        unsigned int dt;
        TRACE_FUN(ft_t_any);

        TRACE_CATCH(ftape_command(command),);
        t0 = ftape_timestamp();
        i = 0;
        do {
                ++i;
                ftape_sleep(3 * FT_MILLISECOND);        /* see remark below */
                TRACE_CATCH(fdc_sense_drive_status(&st3),);
                dt = ftape_timediff(t0, ftape_timestamp());
                /*  Ack should be asserted within Ttimout + Tack = 6 msec.
                 *  Looks like some drives fail to do this so extend this
                 *  period to 300 msec.
                 */
        } while (!(st3 & ST3_TRACK_0) && dt < 300000);
        if (!(st3 & ST3_TRACK_0)) {
                TRACE(ft_t_err,
                      "No acknowledge after %u msec. (%i iter)", dt / 1000, i);
                TRACE_ABORT(-EIO, ft_t_err, "timeout on Acknowledge");
        }
        /*  dt may be larger than expected because of other tasks
         *  scheduled while we were sleeping.
         */
        if (i > 1 && dt > 6000) {
                TRACE(ft_t_err, "Acknowledge after %u msec. (%i iter)",
                      dt / 1000, i);
        }
        *status = 0;
        for (i = 0; i < result_length + 1; i++) {
                TRACE_CATCH(ftape_command(QIC_REPORT_NEXT_BIT),);
                TRACE_CATCH(fdc_sense_drive_status(&st3),);
                if (i < result_length) {
                        *status |= ((st3 & ST3_TRACK_0) ? 1 : 0) << i;
                } else if ((st3 & ST3_TRACK_0) == 0) {
                        TRACE_ABORT(-EIO, ft_t_err, "missing status stop bit");
                }
        }
        /* this command will put track zero and index back into normal state */
        (void)ftape_command(QIC_REPORT_NEXT_BIT);
        TRACE_EXIT 0;
}

/* Report the current drive status. */

int ftape_report_raw_drive_status(int *status)
{
        int result;
        int count = 0;
        TRACE_FUN(ft_t_any);

        do {
                result = ftape_report_operation(status,
                                                QIC_REPORT_DRIVE_STATUS, 8);
        } while (result < 0 && ++count <= 3);
        if (result < 0) {
                TRACE_ABORT(-EIO, ft_t_err,
                            "report_operation failed after %d trials", count);
        }
        if ((*status & 0xff) == 0xff) {
                TRACE_ABORT(-EIO, ft_t_err,
                            "impossible drive status 0xff");
        }
        if (*status & QIC_STATUS_READY) {
                ftape_current_command = QIC_NO_COMMAND; /* completed */
        }
        ft_last_status.status.drive_status = (__u8)(*status & 0xff);
        TRACE_EXIT 0;
}

int ftape_report_drive_status(int *status)
{
        TRACE_FUN(ft_t_any);

        TRACE_CATCH(ftape_report_raw_drive_status(status),);
        if (*status & QIC_STATUS_NEW_CARTRIDGE ||
            !(*status & QIC_STATUS_CARTRIDGE_PRESENT)) {
                ft_failure = 1; /* will inhibit further operations */
                TRACE_EXIT -EIO;
        }
        if (*status & QIC_STATUS_READY && *status & QIC_STATUS_ERROR) {
                /*  Let caller handle all errors */
                TRACE_ABORT(1, ft_t_warn, "warning: error status set!");
        }
        TRACE_EXIT 0;
}

int ftape_report_error(unsigned int *error,
                       qic117_cmd_t *command, int report)
{
        static const ftape_error ftape_errors[] = QIC117_ERRORS;
        int code;
        TRACE_FUN(ft_t_any);

        TRACE_CATCH(ftape_report_operation(&code, QIC_REPORT_ERROR_CODE, 16),);
        *error   = (unsigned int)(code & 0xff);
        *command = (qic117_cmd_t)((code>>8)&0xff);
        /*  remember hardware status, maybe useful for status ioctls
         */
        ft_last_error.error.command = (__u8)*command;
        ft_last_error.error.error   = (__u8)*error;
        if (!report) {
                TRACE_EXIT 0;
        }
        if (*error == 0) {
                TRACE_ABORT(0, ft_t_info, "No error");
        }
        TRACE(ft_t_info, "errorcode: %d", *error);
        if (*error < NR_ITEMS(ftape_errors)) {
                TRACE(ft_t_noise, "%sFatal ERROR:",
                      (ftape_errors[*error].fatal ? "" : "Non-"));
                TRACE(ft_t_noise, "%s ...", ftape_errors[*error].message);
        } else {
                TRACE(ft_t_noise, "Unknown ERROR !");
        }
        if ((unsigned int)*command < NR_ITEMS(qic117_cmds) &&
            qic117_cmds[*command].name != NULL) {
                TRACE(ft_t_noise, "... caused by command \'%s\'",
                      qic117_cmds[*command].name);
        } else {
                TRACE(ft_t_noise, "... caused by unknown command %d",
                      *command);
        }
        TRACE_EXIT 0;
}

int ftape_report_configuration(qic_model *model,
                               unsigned int *rate,
                               int *qic_std,
                               int *tape_len)
{
        int result;
        int config;
        int status;
        static const unsigned int qic_rates[ 4] = { 250, 2000, 500, 1000 };
        TRACE_FUN(ft_t_any);

        result = ftape_report_operation(&config,
                                        QIC_REPORT_DRIVE_CONFIGURATION, 8);
        if (result < 0) {
                ft_last_status.status.drive_config = (__u8)0x00;
                *model = prehistoric;
                *rate = 500;
                *qic_std = QIC_TAPE_QIC40;
                *tape_len = 205;
                TRACE_EXIT 0;
        } else {
                ft_last_status.status.drive_config = (__u8)(config & 0xff);
        }
        *rate = qic_rates[(config & QIC_CONFIG_RATE_MASK) >> QIC_CONFIG_RATE_SHIFT];
        result = ftape_report_operation(&status, QIC_REPORT_TAPE_STATUS, 8);
        if (result < 0) {
                ft_last_status.status.tape_status = (__u8)0x00;
                /* pre- QIC117 rev C spec. drive, QIC_CONFIG_80 bit is valid.
                 */
                *qic_std = (config & QIC_CONFIG_80) ?
                        QIC_TAPE_QIC80 : QIC_TAPE_QIC40;
                /* ?? how's about 425ft tapes? */
                *tape_len = (config & QIC_CONFIG_LONG) ? 307 : 0;
                *model = pre_qic117c;
                result = 0;
        } else {
                ft_last_status.status.tape_status = (__u8)(status & 0xff);
                *model = post_qic117b;
                TRACE(ft_t_any, "report tape status result = %02x", status);
                /* post- QIC117 rev C spec. drive, QIC_CONFIG_80 bit is
                 * invalid. 
                 */
                switch (status & QIC_TAPE_STD_MASK) {
                case QIC_TAPE_QIC40:
                case QIC_TAPE_QIC80:
                case QIC_TAPE_QIC3020:
                case QIC_TAPE_QIC3010:
                        *qic_std = status & QIC_TAPE_STD_MASK;
                        break;
                default:
                        *qic_std = -1;
                        break;
                }
                switch (status & QIC_TAPE_LEN_MASK) {
                case QIC_TAPE_205FT:
                        /* 205 or 425+ ft 550 Oe tape */
                        *tape_len = 0;
                        break;
                case QIC_TAPE_307FT:
                        /* 307.5 ft 550 Oe Extended Length (XL) tape */
                        *tape_len = 307;
                        break;
                case QIC_TAPE_VARIABLE:
                        /* Variable length 550 Oe tape */
                        *tape_len = 0;
                        break;
                case QIC_TAPE_1100FT:
                        /* 1100 ft 550 Oe tape */
                        *tape_len = 1100;
                        break;
                case QIC_TAPE_FLEX:
                        /* Variable length 900 Oe tape */
                        *tape_len = 0;
                        break;
                default:
                        *tape_len = -1;
                        break;
                }
                if (*qic_std == -1 || *tape_len == -1) {
                        TRACE(ft_t_any,
                              "post qic-117b spec drive with unknown tape");
                }
                result = *tape_len == -1 ? -EIO : 0;
                if (status & QIC_TAPE_WIDE) {
                        switch (*qic_std) {
                        case QIC_TAPE_QIC80:
                                TRACE(ft_t_info, "TR-1 tape detected");
                                break;
                        case QIC_TAPE_QIC3010:
                                TRACE(ft_t_info, "TR-2 tape detected");
                                break;
                        case QIC_TAPE_QIC3020:
                                TRACE(ft_t_info, "TR-3 tape detected");
                                break;
                        default:
                                TRACE(ft_t_warn,
                                      "Unknown Travan tape type detected");
                                break;
                        }
                }
        }
        TRACE_EXIT (result < 0) ? -EIO : 0;
}

static int ftape_report_rom_version(int *version)
{

        if (ftape_report_operation(version, QIC_REPORT_ROM_VERSION, 8) < 0) {
                return -EIO;
        } else {
                return 0;
        }
}

void ftape_report_vendor_id(unsigned int *id)
{
        int result;
        TRACE_FUN(ft_t_any);

        /* We'll try to get a vendor id from the drive.  First
         * according to the QIC-117 spec, a 16-bit id is requested.
         * If that fails we'll try an 8-bit version, otherwise we'll
         * try an undocumented query.
         */
        result = ftape_report_operation((int *) id, QIC_REPORT_VENDOR_ID, 16);
        if (result < 0) {
                result = ftape_report_operation((int *) id,
                                                QIC_REPORT_VENDOR_ID, 8);
                if (result < 0) {
                        /* The following is an undocumented call found
                         * in the CMS code.
                         */
                        result = ftape_report_operation((int *) id, 24, 8);
                        if (result < 0) {
                                *id = UNKNOWN_VENDOR;
                        } else {
                                TRACE(ft_t_noise, "got old 8 bit id: %04x",
                                      *id);
                                *id |= 0x20000;
                        }
                } else {
                        TRACE(ft_t_noise, "got 8 bit id: %04x", *id);
                        *id |= 0x10000;
                }
        } else {
                TRACE(ft_t_noise, "got 16 bit id: %04x", *id);
        }
        if (*id == 0x0047) {
                int version;
                int sign;

                if (ftape_report_rom_version(&version) < 0) {
                        TRACE(ft_t_bug, "report rom version failed");
                        TRACE_EXIT;
                }
                TRACE(ft_t_noise, "CMS rom version: %d", version);
                ftape_command(QIC_ENTER_DIAGNOSTIC_1);
                ftape_command(QIC_ENTER_DIAGNOSTIC_1);
                diagnostic_mode = 1;
                if (ftape_report_operation(&sign, 9, 8) < 0) {
                        unsigned int error;
                        qic117_cmd_t command;

                        ftape_report_error(&error, &command, 1);
                        ftape_command(QIC_ENTER_PRIMARY_MODE);
                        diagnostic_mode = 0;
                        TRACE_EXIT;     /* failure ! */
                } else {
                        TRACE(ft_t_noise, "CMS signature: %02x", sign);
                }
                if (sign == 0xa5) {
                        result = ftape_report_operation(&sign, 37, 8);
                        if (result < 0) {
                                if (version >= 63) {
                                        *id = 0x8880;
                                        TRACE(ft_t_noise,
                                              "This is an Iomega drive !");
                                } else {
                                        *id = 0x0047;
                                        TRACE(ft_t_noise,
                                              "This is a real CMS drive !");
                                }
                        } else {
                                *id = 0x0047;
                                TRACE(ft_t_noise, "CMS status: %d", sign);
                        }
                } else {
                        *id = UNKNOWN_VENDOR;
                }
                ftape_command(QIC_ENTER_PRIMARY_MODE);
                diagnostic_mode = 0;
        }
        TRACE_EXIT;
}

static int qic_rate_code(unsigned int rate)
{
        switch (rate) {
        case 250:
                return QIC_CONFIG_RATE_250;
        case 500:
                return QIC_CONFIG_RATE_500;
        case 1000:
                return QIC_CONFIG_RATE_1000;
        case 2000:
                return QIC_CONFIG_RATE_2000;
        default:
                return QIC_CONFIG_RATE_500;
        }
}

static int ftape_set_rate_test(unsigned int *max_rate)
{
        unsigned int error;
        qic117_cmd_t command;
        int status;
        int supported = 0;
        TRACE_FUN(ft_t_any);

        /*  Check if the drive does support the select rate command
         *  by testing all different settings. If any one is accepted
         *  we assume the command is supported, else not.
         */
        for (*max_rate = 2000; *max_rate >= 250; *max_rate /= 2) {
                if (ftape_command(QIC_SELECT_RATE) < 0) {
                        continue;
                }               
                if (ftape_parameter_wait(qic_rate_code(*max_rate),
                                         1 * FT_SECOND, &status) < 0) {
                        continue;
                }
                if (status & QIC_STATUS_ERROR) {
                        ftape_report_error(&error, &command, 0);
                        continue;
                }
                supported = 1; /* did accept a request */
                break;
        }
        TRACE(ft_t_noise, "Select Rate command is%s supported", 
              supported ? "" : " not");
        TRACE_EXIT supported;
}

int ftape_set_data_rate(unsigned int new_rate /* Kbps */, unsigned int qic_std)
{
        int status;
        int result = 0;
        unsigned int data_rate = new_rate;
        static int supported;
        int rate_changed = 0;
        qic_model dummy_model;
        unsigned int dummy_qic_std, dummy_tape_len;
        TRACE_FUN(ft_t_any);

        if (ft_drive_max_rate == 0) { /* first time */
                supported = ftape_set_rate_test(&ft_drive_max_rate);
        }
        if (supported) {
                ftape_command(QIC_SELECT_RATE);
                result = ftape_parameter_wait(qic_rate_code(new_rate),
                                              1 * FT_SECOND, &status);
                if (result >= 0 && !(status & QIC_STATUS_ERROR)) {
                        rate_changed = 1;
                }
        }
        TRACE_CATCH(result = ftape_report_configuration(&dummy_model,
                                                        &data_rate, 
                                                        &dummy_qic_std,
                                                        &dummy_tape_len),);
        if (data_rate != new_rate) {
                if (!supported) {
                        TRACE(ft_t_warn, "Rate change not supported!");
                } else if (rate_changed) {
                        TRACE(ft_t_warn, "Requested: %d, got %d",
                              new_rate, data_rate);
                } else {
                        TRACE(ft_t_warn, "Rate change failed!");
                }
                result = -EINVAL;
        }
        /*
         *  Set data rate and write precompensation as specified:
         *
         *            |  QIC-40/80  | QIC-3010/3020
         *   rate     |   precomp   |    precomp
         *  ----------+-------------+--------------
         *  250 Kbps. |   250 ns.   |     0 ns.
         *  500 Kbps. |   125 ns.   |     0 ns.
         *    1 Mbps. |    42 ns.   |     0 ns.
         *    2 Mbps  |      N/A    |     0 ns.
         */
        if ((qic_std == QIC_TAPE_QIC40 && data_rate > 500) || 
            (qic_std == QIC_TAPE_QIC80 && data_rate > 1000)) {
                TRACE_ABORT(-EINVAL,
                            ft_t_warn, "Datarate too high for QIC-mode");
        }
        TRACE_CATCH(fdc_set_data_rate(data_rate),_res = -EINVAL);
        ft_data_rate = data_rate;
        if (qic_std == QIC_TAPE_QIC40 || qic_std == QIC_TAPE_QIC80) {
                switch (data_rate) {
                case 250:
                        fdc_set_write_precomp(250);
                        break;
                default:
                case 500:
                        fdc_set_write_precomp(125);
                        break;
                case 1000:
                        fdc_set_write_precomp(42);
                        break;
                }
        } else {
                fdc_set_write_precomp(0);
        }
        TRACE_EXIT result;
}

/*  The next two functions are used to cope with excessive overrun errors
 */
int ftape_increase_threshold(void)
{
        TRACE_FUN(ft_t_flow);

        if (fdc.type < i82077 || ft_fdc_threshold >= 12) {
                TRACE_ABORT(-EIO, ft_t_err, "cannot increase fifo threshold");
        }
        if (fdc_fifo_threshold(++ft_fdc_threshold, NULL, NULL, NULL) < 0) {
                TRACE(ft_t_err, "cannot increase fifo threshold");
                ft_fdc_threshold --;
                fdc_reset();
        }
        TRACE(ft_t_info, "New FIFO threshold: %d", ft_fdc_threshold);
        TRACE_EXIT 0;
}

int ftape_half_data_rate(void)
{
        if (ft_data_rate < 500) {
                return -1;
        }
        if (ftape_set_data_rate(ft_data_rate / 2, ft_qic_std) < 0) {
                return -EIO;
        }
        ftape_calc_timeouts(ft_qic_std, ft_data_rate, ftape_tape_len);
        return 0;
}

/*      Seek the head to the specified track.
 */
int ftape_seek_head_to_track(unsigned int track)
{
        int status;
        TRACE_FUN(ft_t_any);

        ft_location.track = -1; /* remains set in case of error */
        if (track >= ft_tracks_per_tape) {
                TRACE_ABORT(-EINVAL, ft_t_bug, "track out of bounds");
        }
        TRACE(ft_t_flow, "seeking track %d", track);
        TRACE_CATCH(ftape_command(QIC_SEEK_HEAD_TO_TRACK),);
        TRACE_CATCH(ftape_parameter_wait(track, ftape_timeout.head_seek,
                                         &status),);
        ft_location.track = track;
        ftape_might_be_off_track = 0;
        TRACE_EXIT 0;
}

int ftape_wakeup_drive(wake_up_types method)
{
        int status;
        int motor_on = 0;
        TRACE_FUN(ft_t_any);

        switch (method) {
        case wake_up_colorado:
                TRACE_CATCH(ftape_command(QIC_PHANTOM_SELECT),);
                TRACE_CATCH(ftape_parameter(0 /* ft_drive_sel ?? */),);
                break;
        case wake_up_mountain:
                TRACE_CATCH(ftape_command(QIC_SOFT_SELECT),);
                ftape_sleep(FT_MILLISECOND);    /* NEEDED */
                TRACE_CATCH(ftape_parameter(18),);
                break;
        case wake_up_insight:
                ftape_sleep(100 * FT_MILLISECOND);
                motor_on = 1;
                fdc_motor(motor_on);    /* enable is done by motor-on */
        case no_wake_up:
                break;
        default:
                TRACE_EXIT -ENODEV;     /* unknown wakeup method */
                break;
        }
        /*  If wakeup succeeded we shouldn't get an error here..
         */
        TRACE_CATCH(ftape_report_raw_drive_status(&status),
                    if (motor_on) {
                            fdc_motor(0);
                    });
        TRACE_EXIT 0;
}

int ftape_put_drive_to_sleep(wake_up_types method)
{
        TRACE_FUN(ft_t_any);

        switch (method) {
        case wake_up_colorado:
                TRACE_CATCH(ftape_command(QIC_PHANTOM_DESELECT),);
                break;
        case wake_up_mountain:
                TRACE_CATCH(ftape_command(QIC_SOFT_DESELECT),);
                break;
        case wake_up_insight:
                fdc_motor(0);   /* enable is done by motor-on */
        case no_wake_up:        /* no wakeup / no sleep ! */
                break;
        default:
                TRACE_EXIT -ENODEV;     /* unknown wakeup method */
        }
        TRACE_EXIT 0;
}

int ftape_reset_drive(void)
{
        int result = 0;
        int status;
        unsigned int err_code;
        qic117_cmd_t err_command;
        int i;
        TRACE_FUN(ft_t_any);

        /*  We want to re-establish contact with our drive.  Fire a
         *  number of reset commands (single step pulses) and pray for
         *  success.
         */
        for (i = 0; i < 2; ++i) {
                TRACE(ft_t_flow, "Resetting fdc");
                fdc_reset();
                ftape_sleep(10 * FT_MILLISECOND);
                TRACE(ft_t_flow, "Reset command to drive");
                result = ftape_command(QIC_RESET);
                if (result == 0) {
                        ftape_sleep(1 * FT_SECOND); /*  drive not
                                                     *  accessible
                                                     *  during 1 second
                                                     */
                        TRACE(ft_t_flow, "Re-selecting drive");

                        /* Strange, the QIC-117 specs don't mention
                         * this but the drive gets deselected after a
                         * soft reset !  So we need to enable it
                         * again.
                         */
                        if (ftape_wakeup_drive(ft_drive_type.wake_up) < 0) {
                                TRACE(ft_t_err, "Wakeup failed !");
                        }
                        TRACE(ft_t_flow, "Waiting until drive gets ready");
                        result= ftape_ready_wait(ftape_timeout.reset, &status);
                        if (result == 0 && (status & QIC_STATUS_ERROR)) {
                                result = ftape_report_error(&err_code,
                                                            &err_command, 1);
                                if (result == 0 && err_code == 27) {
                                        /*  Okay, drive saw reset
                                         *  command and responded as it
                                         *  should
                                         */
                                        break;
                                } else {
                                        result = -EIO;
                                }
                        } else {
                                result = -EIO;
                        }
                }
                FT_SIGNAL_EXIT(_DONT_BLOCK);
        }
        if (result != 0) {
                TRACE(ft_t_err, "General failure to reset tape drive");
        } else {
                /*  Restore correct settings: keep original rate 
                 */
                ftape_set_data_rate(ft_data_rate, ft_qic_std);
        }
        ftape_init_drive_needed = 1;
        TRACE_EXIT result;
}