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/*

 *  linux/atari/stmda.c

 *

 *  Copyright (C) 1994 Roman Hodek

 *

 *

 * 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.

 */

/* This file contains some function for controlling the access to the  */

/* ST-DMA chip that may be shared between devices. Currently we have:  */

/*   TT:     Floppy and ACSI bus                                       */

/*   Falcon: Floppy and SCSI                                           */

/*                                                                     */

/* The controlling functions set up a wait queue for access to the     */

/* ST-DMA chip. Callers to stdma_lock() that cannot granted access are */

/* put onto a queue and waked up later if the owner calls              */

/* stdma_release(). Additionally, the caller gives his interrupt       */

/* service routine to stdma_lock().                                    */

/*                                                                     */

/* On the Falcon, the IDE bus uses just the ACSI/Floppy interrupt, but */

/* not the ST-DMA chip itself. So falhd.c needs not to lock the        */

/* chip. The interrupt is routed to falhd.c if IDE is configured, the  */

/* model is a Falcon and the interrupt was caused by the HD controller */

/* (can be determined by looking at its status register).              */

#include <linux/types.h>

#include <linux/genhd.h>

#include <linux/sched.h>

#include <asm/bootinfo.h>

#include <asm/atari_stdma.h>

#include <asm/atariints.h>

#include <asm/atarihw.h>

#include <asm/atarihdreg.h>

#include <asm/io.h>

#include <asm/irq.h>

static int stdma_locked = 0;                     /* the semaphore */

static isrfunc  stdma_isr = NULL;               /* int func to be called */

static void     *stdma_isr_data = NULL;         /* data passed to isr */

static struct wait_queue *stdma_wait = NULL;    /* wait queue for ST-DMA */

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

static void stdma_int (int irq, struct pt_regs *fp, void *dummy);

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

/*

 * Function: void stdma_lock( isrfunc isr, void *data )

 *

 * Purpose: Tries to get a lock on the ST-DMA chip that is used by more

 *   then one device driver. Waits on stdma_wait until lock is free.

 *   stdma_lock() may not be called from an interrupt! You have to

 *   get the lock in your main routine and release it when your

 *   request is finished.

 *

 * Inputs: A interrupt function that is called until the lock is

 *   released.

 *

 * Returns: nothing

 *

 */

void stdma_lock(isrfunc isr, void *data)

{

        unsigned long   oldflags;

        save_flags(oldflags);

        cli();          /* protect lock */

        while(stdma_locked)

                /* Since the DMA is used for file system purposes, we

                 have to sleep uninterruptible (there may be locked

                 buffers) */

                sleep_on(&stdma_wait);

        stdma_locked   = 1;

        stdma_isr      = isr;

        stdma_isr_data = data;

        restore_flags(oldflags);

}

/*

 * Function: void stdma_release( void )

 *

 * Purpose: Releases the lock on the ST-DMA chip.

 *

 * Inputs: none

 *

 * Returns: nothing

 *

 */

void stdma_release(void)

{

        unsigned long   oldflags;

        save_flags(oldflags);

        cli();

        stdma_locked   = 0;

        stdma_isr      = NULL;

        stdma_isr_data = NULL;

        wake_up(&stdma_wait);

        restore_flags(oldflags);

}

/*

 * Function: int stdma_others_waiting( void )

 *

 * Purpose: Check if someone waits for the ST-DMA lock.

 *

 * Inputs: none

 *

 * Returns: 0 if no one is waiting, != 0 otherwise

 *

 */

int stdma_others_waiting(void)

{

        return waitqueue_active(&stdma_wait);

}

/*

 * Function: int stdma_islocked( void )

 *

 * Purpose: Check if the ST-DMA is currently locked.

 * Note: Returned status is only valid if ints are disabled while calling and

 *       as long as they remain disabled.

 *       If called with ints enabled, status can change only from locked to

 *       unlocked, because ints may not lock the ST-DMA.

 *

 * Inputs: none

 *

 * Returns: != 0 if locked, 0 otherwise

 *

 */

int stdma_islocked(void)

{

        return stdma_locked;

}

/*

 * Function: void stdma_init( void )

 *

 * Purpose: Initialize the ST-DMA chip access controlling.

 *   It sets up the interrupt and its service routine. The int is registered

 *   as slow int, client devices have to live with that (no problem

 *   currently).

 *

 * Inputs: none

 *

 * Return: nothing

 *

 */

void stdma_init(void)

{

        stdma_isr = NULL;

        add_isr(IRQ_MFP_FDC, stdma_int, IRQ_TYPE_SLOW, NULL,

                "ST-DMA: floppy/ACSI/IDE/Falcon-SCSI");

}

/*

 * Function: void stdma_int()

 *

 * Purpose: The interrupt routine for the ST-DMA. It calls the isr

 *   registered by stdma_lock().

 *

 */

static void stdma_int(int irq, struct pt_regs *fp, void *dummy)

{

  if (stdma_isr)

      (*stdma_isr)(irq, fp, stdma_isr_data);

}