summaryrefslogtreecommitdiff
path: root/arch/m68k/atari/stdma.c
blob: e5a66596b116dc7642700aa62638318c73cca135 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
/*
 *  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, IRQ_TYPE_SLOW | 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;
}