--- /dev/null
+/*
+ * 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 <linux/module.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 **************************/
+
+
+/**
+ * stdma_try_lock - attempt to acquire ST DMA interrupt "lock"
+ * @handler: interrupt handler to use after acquisition
+ *
+ * Returns !0 if lock was acquired; otherwise 0.
+ */
+
+int stdma_try_lock(irq_handler_t handler, void *data)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ if (stdma_locked) {
+ local_irq_restore(flags);
+ return 0;
+ }
+
+ stdma_locked = 1;
+ stdma_isr = handler;
+ stdma_isr_data = data;
+ local_irq_restore(flags);
+ return 1;
+}
+EXPORT_SYMBOL(stdma_try_lock);
+
+
+/*
+ * 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)
+{
+ /* Since the DMA is used for file system purposes, we
+ have to sleep uninterruptible (there may be locked
+ buffers) */
+ wait_event(stdma_wait, stdma_try_lock(handler, data));
+}
+EXPORT_SYMBOL(stdma_lock);
+
+
+/*
+ * 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);
+}
+EXPORT_SYMBOL(stdma_release);
+
+
+/**
+ * stdma_is_locked_by - allow lock holder to check whether it needs to release.
+ * @handler: interrupt handler previously used to acquire lock.
+ *
+ * Returns !0 if locked for the given handler; 0 otherwise.
+ */
+
+int stdma_is_locked_by(irq_handler_t handler)
+{
+ unsigned long flags;
+ int result;
+
+ local_irq_save(flags);
+ result = stdma_locked && (stdma_isr == handler);
+ local_irq_restore(flags);
+
+ return result;
+}
+EXPORT_SYMBOL(stdma_is_locked_by);
+
+
+/*
+ * 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;
+}
+EXPORT_SYMBOL(stdma_islocked);
+
+
+/*
+ * 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;
+ if (request_irq(IRQ_MFP_FDC, stdma_int, IRQF_SHARED,
+ "ST-DMA floppy,ACSI,IDE,Falcon-SCSI", stdma_int))
+ pr_err("Couldn't register ST-DMA interrupt\n");
+}
+
+
+/*
+ * 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;
+}
Code Review / kvmfornfv.git / blobdiff