1 /*
2 * linux/arch/m68k/atari/stmda.c
3 *
4 * Copyright (C) 1994 Roman Hodek
5 *
6 *
7 * This file is subject to the terms and conditions of the GNU General Public
8 * License. See the file COPYING in the main directory of this archive
9 * for more details.
10 */
11
12
13 /* This file contains some function for controlling the access to the */
14 /* ST-DMA chip that may be shared between devices. Currently we have: */
15 /* TT: Floppy and ACSI bus */
16 /* Falcon: Floppy and SCSI */
17 /* */
18 /* The controlling functions set up a wait queue for access to the */
19 /* ST-DMA chip. Callers to stdma_lock() that cannot granted access are */
20 /* put onto a queue and waked up later if the owner calls */
21 /* stdma_release(). Additionally, the caller gives his interrupt */
22 /* service routine to stdma_lock(). */
23 /* */
24 /* On the Falcon, the IDE bus uses just the ACSI/Floppy interrupt, but */
25 /* not the ST-DMA chip itself. So falhd.c needs not to lock the */
26 /* chip. The interrupt is routed to falhd.c if IDE is configured, the */
27 /* model is a Falcon and the interrupt was caused by the HD controller */
28 /* (can be determined by looking at its status register). */
29
30
31 #include <linux/types.h>
32 #include <linux/kdev_t.h>
33 #include <linux/genhd.h>
34 #include <linux/sched.h>
35 #include <linux/init.h>
36 #include <linux/interrupt.h>
37 #include <linux/wait.h>
38 #include <linux/module.h>
39
40 #include <asm/atari_stdma.h>
41 #include <asm/atariints.h>
42 #include <asm/atarihw.h>
43 #include <asm/io.h>
44 #include <asm/irq.h>
45
46 static int stdma_locked; /* the semaphore */
47 /* int func to be called */
48 static irq_handler_t stdma_isr;
49 static void *stdma_isr_data; /* data passed to isr */
50 static DECLARE_WAIT_QUEUE_HEAD(stdma_wait); /* wait queue for ST-DMA */
51
52
53
54
55 /***************************** Prototypes *****************************/
56
57 static irqreturn_t stdma_int (int irq, void *dummy);
58
59 /************************* End of Prototypes **************************/
60
61
62
63 /*
64 * Function: void stdma_lock( isrfunc isr, void *data )
65 *
66 * Purpose: Tries to get a lock on the ST-DMA chip that is used by more
67 * then one device driver. Waits on stdma_wait until lock is free.
68 * stdma_lock() may not be called from an interrupt! You have to
69 * get the lock in your main routine and release it when your
70 * request is finished.
71 *
72 * Inputs: A interrupt function that is called until the lock is
73 * released.
74 *
75 * Returns: nothing
76 *
77 */
78
stdma_lock(irq_handler_t handler,void * data)79 void stdma_lock(irq_handler_t handler, void *data)
80 {
81 unsigned long flags;
82
83 local_irq_save(flags); /* protect lock */
84
85 /* Since the DMA is used for file system purposes, we
86 have to sleep uninterruptible (there may be locked
87 buffers) */
88 wait_event(stdma_wait, !stdma_locked);
89
90 stdma_locked = 1;
91 stdma_isr = handler;
92 stdma_isr_data = data;
93 local_irq_restore(flags);
94 }
95 EXPORT_SYMBOL(stdma_lock);
96
97
98 /*
99 * Function: void stdma_release( void )
100 *
101 * Purpose: Releases the lock on the ST-DMA chip.
102 *
103 * Inputs: none
104 *
105 * Returns: nothing
106 *
107 */
108
stdma_release(void)109 void stdma_release(void)
110 {
111 unsigned long flags;
112
113 local_irq_save(flags);
114
115 stdma_locked = 0;
116 stdma_isr = NULL;
117 stdma_isr_data = NULL;
118 wake_up(&stdma_wait);
119
120 local_irq_restore(flags);
121 }
122 EXPORT_SYMBOL(stdma_release);
123
124
125 /*
126 * Function: int stdma_others_waiting( void )
127 *
128 * Purpose: Check if someone waits for the ST-DMA lock.
129 *
130 * Inputs: none
131 *
132 * Returns: 0 if no one is waiting, != 0 otherwise
133 *
134 */
135
stdma_others_waiting(void)136 int stdma_others_waiting(void)
137 {
138 return waitqueue_active(&stdma_wait);
139 }
140 EXPORT_SYMBOL(stdma_others_waiting);
141
142
143 /*
144 * Function: int stdma_islocked( void )
145 *
146 * Purpose: Check if the ST-DMA is currently locked.
147 * Note: Returned status is only valid if ints are disabled while calling and
148 * as long as they remain disabled.
149 * If called with ints enabled, status can change only from locked to
150 * unlocked, because ints may not lock the ST-DMA.
151 *
152 * Inputs: none
153 *
154 * Returns: != 0 if locked, 0 otherwise
155 *
156 */
157
stdma_islocked(void)158 int stdma_islocked(void)
159 {
160 return stdma_locked;
161 }
162 EXPORT_SYMBOL(stdma_islocked);
163
164
165 /*
166 * Function: void stdma_init( void )
167 *
168 * Purpose: Initialize the ST-DMA chip access controlling.
169 * It sets up the interrupt and its service routine. The int is registered
170 * as slow int, client devices have to live with that (no problem
171 * currently).
172 *
173 * Inputs: none
174 *
175 * Return: nothing
176 *
177 */
178
stdma_init(void)179 void __init stdma_init(void)
180 {
181 stdma_isr = NULL;
182 if (request_irq(IRQ_MFP_FDC, stdma_int, IRQ_TYPE_SLOW | IRQF_SHARED,
183 "ST-DMA: floppy/ACSI/IDE/Falcon-SCSI", stdma_int))
184 pr_err("Couldn't register ST-DMA interrupt\n");
185 }
186
187
188 /*
189 * Function: void stdma_int()
190 *
191 * Purpose: The interrupt routine for the ST-DMA. It calls the isr
192 * registered by stdma_lock().
193 *
194 */
195
stdma_int(int irq,void * dummy)196 static irqreturn_t stdma_int(int irq, void *dummy)
197 {
198 if (stdma_isr)
199 (*stdma_isr)(irq, stdma_isr_data);
200 return IRQ_HANDLED;
201 }
202