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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/sched.h>
34#include <linux/init.h>
35#include <linux/interrupt.h>
36#include <linux/wait.h>
37#include <linux/module.h>
38
39#include <asm/atari_stdma.h>
40#include <asm/atariints.h>
41#include <asm/atarihw.h>
42#include <asm/io.h>
43#include <asm/irq.h>
44
45static int stdma_locked; /* the semaphore */
46 /* int func to be called */
47static irq_handler_t stdma_isr;
48static void *stdma_isr_data; /* data passed to isr */
49static DECLARE_WAIT_QUEUE_HEAD(stdma_wait); /* wait queue for ST-DMA */
50
51
52
53
54/***************************** Prototypes *****************************/
55
56static irqreturn_t stdma_int (int irq, void *dummy);
57
58/************************* End of Prototypes **************************/
59
60
61/**
62 * stdma_try_lock - attempt to acquire ST DMA interrupt "lock"
63 * @handler: interrupt handler to use after acquisition
64 * @data: cookie passed to the interrupt handler function
65 *
66 * Returns !0 if lock was acquired; otherwise 0.
67 */
68
69int stdma_try_lock(irq_handler_t handler, void *data)
70{
71 unsigned long flags;
72
73 local_irq_save(flags);
74 if (stdma_locked) {
75 local_irq_restore(flags);
76 return 0;
77 }
78
79 stdma_locked = 1;
80 stdma_isr = handler;
81 stdma_isr_data = data;
82 local_irq_restore(flags);
83 return 1;
84}
85EXPORT_SYMBOL(stdma_try_lock);
86
87
88/*
89 * Function: void stdma_lock( isrfunc isr, void *data )
90 *
91 * Purpose: Tries to get a lock on the ST-DMA chip that is used by more
92 * then one device driver. Waits on stdma_wait until lock is free.
93 * stdma_lock() may not be called from an interrupt! You have to
94 * get the lock in your main routine and release it when your
95 * request is finished.
96 *
97 * Inputs: A interrupt function that is called until the lock is
98 * released.
99 *
100 * Returns: nothing
101 *
102 */
103
104void stdma_lock(irq_handler_t handler, void *data)
105{
106 /* Since the DMA is used for file system purposes, we
107 have to sleep uninterruptible (there may be locked
108 buffers) */
109 wait_event(stdma_wait, stdma_try_lock(handler, data));
110}
111EXPORT_SYMBOL(stdma_lock);
112
113
114/*
115 * Function: void stdma_release( void )
116 *
117 * Purpose: Releases the lock on the ST-DMA chip.
118 *
119 * Inputs: none
120 *
121 * Returns: nothing
122 *
123 */
124
125void stdma_release(void)
126{
127 unsigned long flags;
128
129 local_irq_save(flags);
130
131 stdma_locked = 0;
132 stdma_isr = NULL;
133 stdma_isr_data = NULL;
134 wake_up(&stdma_wait);
135
136 local_irq_restore(flags);
137}
138EXPORT_SYMBOL(stdma_release);
139
140
141/**
142 * stdma_is_locked_by - allow lock holder to check whether it needs to release.
143 * @handler: interrupt handler previously used to acquire lock.
144 *
145 * Returns !0 if locked for the given handler; 0 otherwise.
146 */
147
148int stdma_is_locked_by(irq_handler_t handler)
149{
150 unsigned long flags;
151 int result;
152
153 local_irq_save(flags);
154 result = stdma_locked && (stdma_isr == handler);
155 local_irq_restore(flags);
156
157 return result;
158}
159EXPORT_SYMBOL(stdma_is_locked_by);
160
161
162/*
163 * Function: int stdma_islocked( void )
164 *
165 * Purpose: Check if the ST-DMA is currently locked.
166 * Note: Returned status is only valid if ints are disabled while calling and
167 * as long as they remain disabled.
168 * If called with ints enabled, status can change only from locked to
169 * unlocked, because ints may not lock the ST-DMA.
170 *
171 * Inputs: none
172 *
173 * Returns: != 0 if locked, 0 otherwise
174 *
175 */
176
177int stdma_islocked(void)
178{
179 return stdma_locked;
180}
181EXPORT_SYMBOL(stdma_islocked);
182
183
184/*
185 * Function: void stdma_init( void )
186 *
187 * Purpose: Initialize the ST-DMA chip access controlling.
188 * It sets up the interrupt and its service routine. The int is registered
189 * as slow int, client devices have to live with that (no problem
190 * currently).
191 *
192 * Inputs: none
193 *
194 * Return: nothing
195 *
196 */
197
198void __init stdma_init(void)
199{
200 stdma_isr = NULL;
201 if (request_irq(IRQ_MFP_FDC, stdma_int, IRQF_SHARED,
202 "ST-DMA floppy,ACSI,IDE,Falcon-SCSI", stdma_int))
203 pr_err("Couldn't register ST-DMA interrupt\n");
204}
205
206
207/*
208 * Function: void stdma_int()
209 *
210 * Purpose: The interrupt routine for the ST-DMA. It calls the isr
211 * registered by stdma_lock().
212 *
213 */
214
215static irqreturn_t stdma_int(int irq, void *dummy)
216{
217 if (stdma_isr)
218 (*stdma_isr)(irq, stdma_isr_data);
219 return IRQ_HANDLED;
220}