196 lines
4.8 KiB
C
196 lines
4.8 KiB
C
/*
|
|
* linux/arch/m68k/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/kdev_t.h>
|
|
#include <linux/genhd.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/init.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/wait.h>
|
|
|
|
#include <asm/atari_stdma.h>
|
|
#include <asm/atariints.h>
|
|
#include <asm/atarihw.h>
|
|
#include <asm/io.h>
|
|
#include <asm/irq.h>
|
|
|
|
static int stdma_locked; /* the semaphore */
|
|
/* int func to be called */
|
|
static irq_handler_t stdma_isr;
|
|
static void *stdma_isr_data; /* data passed to isr */
|
|
static DECLARE_WAIT_QUEUE_HEAD(stdma_wait); /* wait queue for ST-DMA */
|
|
|
|
|
|
|
|
|
|
/***************************** Prototypes *****************************/
|
|
|
|
static irqreturn_t stdma_int (int irq, 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(irq_handler_t handler, void *data)
|
|
{
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags); /* protect lock */
|
|
|
|
/* Since the DMA is used for file system purposes, we
|
|
have to sleep uninterruptible (there may be locked
|
|
buffers) */
|
|
wait_event(stdma_wait, !stdma_locked);
|
|
|
|
stdma_locked = 1;
|
|
stdma_isr = handler;
|
|
stdma_isr_data = data;
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
|
|
/*
|
|
* Function: void stdma_release( void )
|
|
*
|
|
* Purpose: Releases the lock on the ST-DMA chip.
|
|
*
|
|
* Inputs: none
|
|
*
|
|
* Returns: nothing
|
|
*
|
|
*/
|
|
|
|
void stdma_release(void)
|
|
{
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
|
|
stdma_locked = 0;
|
|
stdma_isr = NULL;
|
|
stdma_isr_data = NULL;
|
|
wake_up(&stdma_wait);
|
|
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
|
|
/*
|
|
* 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 __init stdma_init(void)
|
|
{
|
|
stdma_isr = NULL;
|
|
request_irq(IRQ_MFP_FDC, stdma_int, IRQ_TYPE_SLOW | IRQF_SHARED,
|
|
"ST-DMA: floppy/ACSI/IDE/Falcon-SCSI", stdma_int);
|
|
}
|
|
|
|
|
|
/*
|
|
* Function: void stdma_int()
|
|
*
|
|
* Purpose: The interrupt routine for the ST-DMA. It calls the isr
|
|
* registered by stdma_lock().
|
|
*
|
|
*/
|
|
|
|
static irqreturn_t stdma_int(int irq, void *dummy)
|
|
{
|
|
if (stdma_isr)
|
|
(*stdma_isr)(irq, stdma_isr_data);
|
|
return IRQ_HANDLED;
|
|
}
|