fdc-io.c

linux-2.6.15.6

/*
 * Copyright (C) 1993-1996 Bas Laarhoven,
 *           (C) 1996-1997 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/fdc-io.c,v $
 * $Revision: 1.7.4.2 $
 * $Date: 1997/11/16 14:48:17 $
 *
 *      This file contains the low-level floppy disk interface code
 *      for the QIC-40/80/3010/3020 floppy-tape driver "ftape" for
 *      Linux.
 */

#include <linux/config.h> /* for CONFIG_FT_* */
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/dma.h>
#include <asm/irq.h>

#include <linux/ftape.h>
#include <linux/qic117.h>
#include "../lowlevel/ftape-tracing.h"
#include "../lowlevel/fdc-io.h"
#include "../lowlevel/fdc-isr.h"
#include "../lowlevel/ftape-io.h"
#include "../lowlevel/ftape-rw.h"
#include "../lowlevel/ftape-ctl.h"
#include "../lowlevel/ftape-calibr.h"
#include "../lowlevel/fc-10.h"

/*      Global vars.
 */
static int ftape_motor;
volatile int ftape_current_cylinder = -1;
volatile fdc_mode_enum fdc_mode = fdc_idle;
fdc_config_info fdc;
DECLARE_WAIT_QUEUE_HEAD(ftape_wait_intr);

unsigned int ft_fdc_base       = CONFIG_FT_FDC_BASE;
unsigned int ft_fdc_irq        = CONFIG_FT_FDC_IRQ;
unsigned int ft_fdc_dma        = CONFIG_FT_FDC_DMA;
unsigned int ft_fdc_threshold  = CONFIG_FT_FDC_THR;  /* bytes */
unsigned int ft_fdc_rate_limit = CONFIG_FT_FDC_MAX_RATE; /* bits/sec */
int ft_probe_fc10        = CONFIG_FT_PROBE_FC10;
int ft_mach2             = CONFIG_FT_MACH2;

/*      Local vars.
 */
static spinlock_t fdc_io_lock; 
static unsigned int fdc_calibr_count;
static unsigned int fdc_calibr_time;
static int fdc_status;
volatile __u8 fdc_head;		/* FDC head from sector id */
volatile __u8 fdc_cyl;		/* FDC track from sector id */
volatile __u8 fdc_sect;		/* FDC sector from sector id */
static int fdc_data_rate = 500;	/* data rate (Kbps) */
static int fdc_rate_code;	/* data rate code (0 == 500 Kbps) */
static int fdc_seek_rate = 2;	/* step rate (msec) */
static void (*do_ftape) (void);
static int fdc_fifo_state;	/* original fifo setting - fifo enabled */
static int fdc_fifo_thr;	/* original fifo setting - threshold */
static int fdc_lock_state;	/* original lock setting - locked */
static int fdc_fifo_locked;	/* has fifo && lock set ? */
static __u8 fdc_precomp;	/* default precomp. value (nsec) */
static __u8 fdc_prec_code;	/* fdc precomp. select code */

static char ftape_id[] = "ftape";  /* used by request irq and free irq */

static int fdc_set_seek_rate(int seek_rate);

void fdc_catch_stray_interrupts(int count)
{
	unsigned long flags;

	spin_lock_irqsave(&fdc_io_lock, flags);
	if (count == 0) {
		ft_expected_stray_interrupts = 0;
	} else {
		ft_expected_stray_interrupts += count;
	}
	spin_unlock_irqrestore(&fdc_io_lock, flags);
}

/*  Wait during a timeout period for a given FDC status.
 *  If usecs == 0 then just test status, else wait at least for usecs.
 *  Returns -ETIME on timeout. Function must be calibrated first !
 */
static int fdc_wait(unsigned int usecs, __u8 mask, __u8 state)
{
	int count_1 = (fdc_calibr_count * usecs +
                       fdc_calibr_count - 1) / fdc_calibr_time;

	do {
		fdc_status = inb_p(fdc.msr);
		if ((fdc_status & mask) == state) {
			return 0;
		}
	} while (count_1-- >= 0);
	return -ETIME;
}

int fdc_ready_wait(unsigned int usecs)
{
	return fdc_wait(usecs, FDC_DATA_READY | FDC_BUSY, FDC_DATA_READY);
}

/* Why can't we just use udelay()?
 */
static void fdc_usec_wait(unsigned int usecs)
{
	fdc_wait(usecs, 0, 1);	/* will always timeout ! */
}

static int fdc_ready_out_wait(unsigned int usecs)
{
	fdc_usec_wait(FT_RQM_DELAY);	/* wait for valid RQM status */
	return fdc_wait(usecs, FDC_DATA_OUT_READY, FDC_DATA_OUT_READY);
}

void fdc_wait_calibrate(void)
{
	ftape_calibrate("fdc_wait",
			fdc_usec_wait, &fdc_calibr_count, &fdc_calibr_time); 
}

/*  Wait for a (short) while for the FDC to become ready
 *  and transfer the next command byte.
 *  Return -ETIME on timeout on getting ready (depends on hardware!).
 */
static int fdc_write(const __u8 data)
{
	fdc_usec_wait(FT_RQM_DELAY);	/* wait for valid RQM status */
	if (fdc_wait(150, FDC_DATA_READY_MASK, FDC_DATA_IN_READY) < 0) {
		return -ETIME;
	} else {
		outb(data, fdc.fifo);
		return 0;
	}
}

/*  Wait for a (short) while for the FDC to become ready
 *  and transfer the next result byte.
 *  Return -ETIME if timeout on getting ready (depends on hardware!).
 */
static int fdc_read(__u8 * data)
{
	fdc_usec_wait(FT_RQM_DELAY);	/* wait for valid RQM status */
	if (fdc_wait(150, FDC_DATA_READY_MASK, FDC_DATA_OUT_READY) < 0) {
		return -ETIME;
	} else {
		*data = inb(fdc.fifo);
		return 0;
	}
}

/*  Output a cmd_len long command string to the FDC.
 *  The FDC should be ready to receive a new command or
 *  an error (EBUSY or ETIME) will occur.
 */
int fdc_command(const __u8 * cmd_data, int cmd_len)
{
	int result = 0;
	unsigned long flags;
	int count = cmd_len;
	int retry = 0;
#ifdef TESTING
	static unsigned int last_time;
	unsigned int time;
#endif
	TRACE_FUN(ft_t_any);

	fdc_usec_wait(FT_RQM_DELAY);	/* wait for valid RQM status */
	spin_lock_irqsave(&fdc_io_lock, flags);
	if (!in_interrupt())
		/* Yes, I know, too much comments inside this function
		 * ...
		 * 
		 * Yet another bug in the original driver. All that
		 * havoc is caused by the fact that the isr() sends
		 * itself a command to the floppy tape driver (pause,
		 * micro step pause).  Now, the problem is that
		 * commands are transmitted via the fdc_seek
		 * command. But: the fdc performs seeks in the
		 * background i.e. it doesn't signal busy while
		 * sending the step pulses to the drive. Therefore the
		 * non-interrupt level driver has no chance to tell
		 * whether the isr() just has issued a seek. Therefore
		 * we HAVE TO have a look at the ft_hide_interrupt
		 * flag: it signals the non-interrupt level part of
		 * the driver that it has to wait for the fdc until it
		 * has completet seeking.
		 *
		 * THIS WAS PRESUMABLY THE REASON FOR ALL THAT
		 * "fdc_read timeout" errors, I HOPE :-)
		 */
		if (ft_hide_interrupt) {
			restore_flags(flags);
			TRACE(ft_t_info,
			      "Waiting for the isr() completing fdc_seek()");
			if (fdc_interrupt_wait(2 * FT_SECOND) < 0) {
				TRACE(ft_t_warn,
		      "Warning: timeout waiting for isr() seek to complete");
			}
			if (ft_hide_interrupt || !ft_seek_completed) {
				/* There cannot be another
				 * interrupt. The isr() only stops
				 * the tape and the next interrupt
				 * won't come until we have send our
				 * command to the drive.
				 */
				TRACE_ABORT(-EIO, ft_t_bug,
					    "BUG? isr() is still seeking?\n"
					    KERN_INFO "hide: %d\n"
					    KERN_INFO "seek: %d",
					    ft_hide_interrupt,
					    ft_seek_completed);

			}
			fdc_usec_wait(FT_RQM_DELAY);	/* wait for valid RQM status */
			spin_lock_irqsave(&fdc_io_lock, flags);
		}
	fdc_status = inb(fdc.msr);
	if ((fdc_status & FDC_DATA_READY_MASK) != FDC_DATA_IN_READY) {
		spin_unlock_irqrestore(&fdc_io_lock, flags);
		TRACE_ABORT(-EBUSY, ft_t_err, "fdc not ready");
	} 
	fdc_mode = *cmd_data;	/* used by isr */
#ifdef TESTING
	if (fdc_mode == FDC_SEEK) {
		time = ftape_timediff(last_time, ftape_timestamp());
		if (time < 6000) {
	TRACE(ft_t_bug,"Warning: short timeout between seek commands: %d",
	      time);
		}
	}
#endif
	if (!in_interrupt()) {
		/* shouldn't be cleared if called from isr
		 */
		ft_interrupt_seen = 0;
	}
	while (count) {
		result = fdc_write(*cmd_data);
		if (result < 0) {
			TRACE(ft_t_fdc_dma,
			      "fdc_mode = %02x, status = %02x at index %d",
			      (int) fdc_mode, (int) fdc_status,
			      cmd_len - count);
			if (++retry <= 3) {
				TRACE(ft_t_warn, "fdc_write timeout, retry");
			} else {
				TRACE(ft_t_err, "fdc_write timeout, fatal");
				/* recover ??? */
				break;
			}
		} else {
			--count;
			++cmd_data;
		}
        }
#ifdef TESTING
	if (fdc_mode == FDC_SEEK) {
		last_time = ftape_timestamp();
	}
#endif
	spin_unlock_irqrestore(&fdc_io_lock, flags);
	TRACE_EXIT result;
}

/*  Input a res_len long result string from the FDC.
 *  The FDC should be ready to send the result or an error
 *  (EBUSY or ETIME) will occur.
 */
int fdc_result(__u8 * res_data, int res_len)
{
	int result = 0;
	unsigned long flags;
	int count = res_len;
	int retry = 0;
	TRACE_FUN(ft_t_any);

	spin_lock_irqsave(&fdc_io_lock, flags);
	fdc_status = inb(fdc.msr);
	if ((fdc_status & FDC_DATA_READY_MASK) != FDC_DATA_OUT_READY) {
		TRACE(ft_t_err, "fdc not ready");
		result = -EBUSY;
	} else while (count) {
		if (!(fdc_status & FDC_BUSY)) {
			spin_unlock_irqrestore(&fdc_io_lock, flags);
			TRACE_ABORT(-EIO, ft_t_err, "premature end of result phase");
		}
		result = fdc_read(res_data);
		if (result < 0) {
			TRACE(ft_t_fdc_dma,
			      "fdc_mode = %02x, status = %02x at index %d",
			      (int) fdc_mode,
			      (int) fdc_status,
			      res_len - count);
			if (++retry <= 3) {
				TRACE(ft_t_warn, "fdc_read timeout, retry");
			} else {
				TRACE(ft_t_err, "fdc_read timeout, fatal");
				/* recover ??? */
				break;
				++retry;
			}
		} else {
			--count;
			++res_data;
		}
	}
	spin_unlock_irqrestore(&fdc_io_lock, flags);
	fdc_usec_wait(FT_RQM_DELAY);	/* allow FDC to negate BSY */
	TRACE_EXIT result;
}

/*      Handle command and result phases for
 *      commands without data phase.
 */
static int fdc_issue_command(const __u8 * out_data, int out_count,
		      __u8 * in_data, int in_count)
{
	TRACE_FUN(ft_t_any);

	if (out_count > 0) {
		TRACE_CATCH(fdc_command(out_data, out_count),);
	}
	/* will take 24 - 30 usec for fdc_sense_drive_status and
	 * fdc_sense_interrupt_status commands.
	 *    35 fails sometimes (5/9/93 SJL)
	 * On a loaded system it incidentally takes longer than
	 * this for the fdc to get ready ! ?????? WHY ??????
	 * So until we know what's going on use a very long timeout.
	 */
	TRACE_CATCH(fdc_ready_out_wait(500 /* usec */),);
	if (in_count > 0) {
		TRACE_CATCH(fdc_result(in_data, in_count),
			    TRACE(ft_t_err, "result phase aborted"));
	}
	TRACE_EXIT 0;
}

/*      Wait for FDC interrupt with timeout (in milliseconds).
 *      Signals are blocked so the wait will not be aborted.
 *      Note: interrupts must be enabled ! (23/05/93 SJL)
 */
int fdc_interrupt_wait(unsigned int time)
{
	DECLARE_WAITQUEUE(wait,current);
	sigset_t old_sigmask;	
	static int resetting;
	long timeout;

	TRACE_FUN(ft_t_fdc_dma);

 	if (waitqueue_active(&ftape_wait_intr)) {
		TRACE_ABORT(-EIO, ft_t_err, "error: nested call");
	}
	/* timeout time will be up to USPT microseconds too long ! */
	timeout = (1000 * time + FT_USPT - 1) / FT_USPT;

	spin_lock_irq(&current->sighand->siglock);
	old_sigmask = current->blocked;
	sigfillset(&current->blocked);
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	set_current_state(TASK_INTERRUPTIBLE);
	add_wait_queue(&ftape_wait_intr, &wait);
	while (!ft_interrupt_seen && timeout)
		timeout = schedule_timeout_interruptible(timeout);

	spin_lock_irq(&current->sighand->siglock);
	current->blocked = old_sigmask;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);
	
	remove_wait_queue(&ftape_wait_intr, &wait);
	/*  the following IS necessary. True: as well
	 *  wake_up_interruptible() as the schedule() set TASK_RUNNING
	 *  when they wakeup a task, BUT: it may very well be that
	 *  ft_interrupt_seen is already set to 1 when we enter here
	 *  in which case schedule() gets never called, and
	 *  TASK_RUNNING never set. This has the funny effect that we
	 *  execute all the code until we leave kernel space, but then
	 *  the task is stopped (a task CANNOT be preempted while in
	 *  kernel mode. Sending a pair of SIGSTOP/SIGCONT to the
	 *  tasks wakes it up again. Funny! :-)
	 */
	current->state = TASK_RUNNING; 
	if (ft_interrupt_seen) { /* woken up by interrupt */
		ft_interrupt_seen = 0;
		TRACE_EXIT 0;
	}
	/*  Original comment:
	 *  In first instance, next statement seems unnecessary since
	 *  it will be cleared in fdc_command. However, a small part of
	 *  the software seems to rely on this being cleared here
	 *  (ftape_close might fail) so stick to it until things get fixed !
	 */
	/*  My deeply sought of knowledge:
	 *  Behold NO! It is obvious. fdc_reset() doesn't call fdc_command()
	 *  but nevertheless uses fdc_interrupt_wait(). OF COURSE this needs to
	 *  be reset here.
	 */
	ft_interrupt_seen = 0;	/* clear for next call */
	if (!resetting) {
		resetting = 1;	/* break infinite recursion if reset fails */
		TRACE(ft_t_any, "cleanup reset");
		fdc_reset();
		resetting = 0;
	}
	TRACE_EXIT (signal_pending(current)) ? -EINTR : -ETIME;
}

/*      Start/stop drive motor. Enable DMA mode.
 */
void fdc_motor(int motor)
{
	int unit = ft_drive_sel;
	int data = unit | FDC_RESET_NOT | FDC_DMA_MODE;
	TRACE_FUN(ft_t_any);

	ftape_motor = motor;
	if (ftape_motor) {
		data |= FDC_MOTOR_0 << unit;
		TRACE(ft_t_noise, "turning motor %d on", unit);
	} else {
		TRACE(ft_t_noise, "turning motor %d off", unit);
	}
	if (ft_mach2) {