xref: /openbmc/linux/arch/m68k/atari/ataints.c (revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2)
1 /*
2  * arch/m68k/atari/ataints.c -- Atari Linux interrupt handling code
3  *
4  * 5/2/94 Roman Hodek:
5  *  Added support for TT interrupts; setup for TT SCU (may someone has
6  *  twiddled there and we won't get the right interrupts :-()
7  *
8  *  Major change: The device-independent code in m68k/ints.c didn't know
9  *  about non-autovec ints yet. It hardcoded the number of possible ints to
10  *  7 (IRQ1...IRQ7). But the Atari has lots of non-autovec ints! I made the
11  *  number of possible ints a constant defined in interrupt.h, which is
12  *  47 for the Atari. So we can call request_irq() for all Atari interrupts
13  *  just the normal way. Additionally, all vectors >= 48 are initialized to
14  *  call trap() instead of inthandler(). This must be changed here, too.
15  *
16  * 1995-07-16 Lars Brinkhoff <f93labr@dd.chalmers.se>:
17  *  Corrected a bug in atari_add_isr() which rejected all SCC
18  *  interrupt sources if there were no TT MFP!
19  *
20  * 12/13/95: New interface functions atari_level_triggered_int() and
21  *  atari_register_vme_int() as support for level triggered VME interrupts.
22  *
23  * 02/12/96: (Roman)
24  *  Total rewrite of Atari interrupt handling, for new scheme see comments
25  *  below.
26  *
27  * 1996-09-03 lars brinkhoff <f93labr@dd.chalmers.se>:
28  *  Added new function atari_unregister_vme_int(), and
29  *  modified atari_register_vme_int() as well as IS_VALID_INTNO()
30  *  to work with it.
31  *
32  * This file is subject to the terms and conditions of the GNU General Public
33  * License.  See the file COPYING in the main directory of this archive
34  * for more details.
35  *
36  */
37 
38 #include <linux/types.h>
39 #include <linux/kernel.h>
40 #include <linux/kernel_stat.h>
41 #include <linux/init.h>
42 #include <linux/seq_file.h>
43 
44 #include <asm/system.h>
45 #include <asm/traps.h>
46 
47 #include <asm/atarihw.h>
48 #include <asm/atariints.h>
49 #include <asm/atari_stdma.h>
50 #include <asm/irq.h>
51 #include <asm/entry.h>
52 
53 
54 /*
55  * Atari interrupt handling scheme:
56  * --------------------------------
57  *
58  * All interrupt source have an internal number (defined in
59  * <asm/atariints.h>): Autovector interrupts are 1..7, then follow ST-MFP,
60  * TT-MFP, SCC, and finally VME interrupts. Vector numbers for the latter can
61  * be allocated by atari_register_vme_int().
62  *
63  * Each interrupt can be of three types:
64  *
65  *  - SLOW: The handler runs with all interrupts enabled, except the one it
66  *    was called by (to avoid reentering). This should be the usual method.
67  *    But it is currently possible only for MFP ints, since only the MFP
68  *    offers an easy way to mask interrupts.
69  *
70  *  - FAST: The handler runs with all interrupts disabled. This should be used
71  *    only for really fast handlers, that just do actions immediately
72  *    necessary, and let the rest do a bottom half or task queue.
73  *
74  *  - PRIORITIZED: The handler can be interrupted by higher-level ints
75  *    (greater IPL, no MFP priorities!). This is the method of choice for ints
76  *    which should be slow, but are not from a MFP.
77  *
78  * The feature of more than one handler for one int source is still there, but
79  * only applicable if all handers are of the same type. To not slow down
80  * processing of ints with only one handler by the chaining feature, the list
81  * calling function atari_call_irq_list() is only plugged in at the time the
82  * second handler is registered.
83  *
84  * Implementation notes: For fast-as-possible int handling, there are separate
85  * entry points for each type (slow/fast/prio). The assembler handler calls
86  * the irq directly in the usual case, no C wrapper is involved. In case of
87  * multiple handlers, atari_call_irq_list() is registered as handler and calls
88  * in turn the real irq's. To ease access from assembler level to the irq
89  * function pointer and accompanying data, these two are stored in a separate
90  * array, irq_handler[]. The rest of data (type, name) are put into a second
91  * array, irq_param, that is accessed from C only. For each slow interrupt (32
92  * in all) there are separate handler functions, which makes it possible to
93  * hard-code the MFP register address and value, are necessary to mask the
94  * int. If there'd be only one generic function, lots of calculations would be
95  * needed to determine MFP register and int mask from the vector number :-(
96  *
97  * Furthermore, slow ints may not lower the IPL below its previous value
98  * (before the int happened). This is needed so that an int of class PRIO, on
99  * that this int may be stacked, cannot be reentered. This feature is
100  * implemented as follows: If the stack frame format is 1 (throwaway), the int
101  * is not stacked, and the IPL is anded with 0xfbff, resulting in a new level
102  * 2, which still blocks the HSYNC, but no interrupts of interest. If the
103  * frame format is 0, the int is nested, and the old IPL value can be found in
104  * the sr copy in the frame.
105  */
106 
107 
108 #define	NUM_INT_SOURCES	(8 + NUM_ATARI_SOURCES)
109 
110 typedef void (*asm_irq_handler)(void);
111 
112 struct irqhandler {
113 	irqreturn_t (*handler)(int, void *, struct pt_regs *);
114 	void	*dev_id;
115 };
116 
117 struct irqparam {
118 	unsigned long	flags;
119 	const char	*devname;
120 };
121 
122 /*
123  * Array with irq's and their parameter data. This array is accessed from low
124  * level assembler code, so an element size of 8 allows usage of index scaling
125  * addressing mode.
126  */
127 static struct irqhandler irq_handler[NUM_INT_SOURCES];
128 
129 /*
130  * This array hold the rest of parameters of int handlers: type
131  * (slow,fast,prio) and the name of the handler. These values are only
132  * accessed from C
133  */
134 static struct irqparam irq_param[NUM_INT_SOURCES];
135 
136 /*
137  * Bitmap for free interrupt vector numbers
138  * (new vectors starting from 0x70 can be allocated by
139  * atari_register_vme_int())
140  */
141 static int free_vme_vec_bitmap;
142 
143 /* check for valid int number (complex, sigh...) */
144 #define	IS_VALID_INTNO(n)											\
145 	((n) > 0 &&														\
146 	 /* autovec and ST-MFP ok anyway */								\
147 	 (((n) < TTMFP_SOURCE_BASE) ||									\
148 	  /* TT-MFP ok if present */									\
149 	  ((n) >= TTMFP_SOURCE_BASE && (n) < SCC_SOURCE_BASE &&			\
150 	   ATARIHW_PRESENT(TT_MFP)) ||									\
151 	  /* SCC ok if present and number even */						\
152 	  ((n) >= SCC_SOURCE_BASE && (n) < VME_SOURCE_BASE &&			\
153 	   !((n) & 1) && ATARIHW_PRESENT(SCC)) ||						\
154 	  /* greater numbers ok if they are registered VME vectors */		\
155 	  ((n) >= VME_SOURCE_BASE && (n) < VME_SOURCE_BASE + VME_MAX_SOURCES && \
156 		  free_vme_vec_bitmap & (1 << ((n) - VME_SOURCE_BASE)))))
157 
158 
159 /*
160  * Here start the assembler entry points for interrupts
161  */
162 
163 #define IRQ_NAME(nr) atari_slow_irq_##nr##_handler(void)
164 
165 #define	BUILD_SLOW_IRQ(n)						   \
166 asmlinkage void IRQ_NAME(n);						   \
167 /* Dummy function to allow asm with operands.  */			   \
168 void atari_slow_irq_##n##_dummy (void) {				   \
169 __asm__ (__ALIGN_STR "\n"						   \
170 "atari_slow_irq_" #n "_handler:\t"					   \
171 "	addl	%6,%5\n"	/* preempt_count() += HARDIRQ_OFFSET */	   \
172 	SAVE_ALL_INT "\n"						   \
173 	GET_CURRENT(%%d0) "\n"						   \
174 "	andb	#~(1<<(%c3&7)),%a4:w\n"	/* mask this interrupt */	   \
175 	/* get old IPL from stack frame */				   \
176 "	bfextu	%%sp@(%c2){#5,#3},%%d0\n"				   \
177 "	movew	%%sr,%%d1\n"						   \
178 "	bfins	%%d0,%%d1{#21,#3}\n"					   \
179 "	movew	%%d1,%%sr\n"		/* set IPL = previous value */	   \
180 "	addql	#1,%a0\n"						   \
181 "	lea	%a1,%%a0\n"						   \
182 "	pea	%%sp@\n"		/* push addr of frame */	   \
183 "	movel	%%a0@(4),%%sp@-\n"	/* push handler data */		   \
184 "	pea	(%c3+8)\n"		/* push int number */		   \
185 "	movel	%%a0@,%%a0\n"						   \
186 "	jbsr	%%a0@\n"		/* call the handler */		   \
187 "	addql	#8,%%sp\n"						   \
188 "	addql	#4,%%sp\n"						   \
189 "	orw	#0x0600,%%sr\n"						   \
190 "	andw	#0xfeff,%%sr\n"		/* set IPL = 6 again */		   \
191 "	orb	#(1<<(%c3&7)),%a4:w\n"	/* now unmask the int again */	   \
192 "	jbra	ret_from_interrupt\n"					   \
193 	 : : "i" (&kstat_cpu(0).irqs[n+8]), "i" (&irq_handler[n+8]),	   \
194 	     "n" (PT_OFF_SR), "n" (n),					   \
195 	     "i" (n & 8 ? (n & 16 ? &tt_mfp.int_mk_a : &mfp.int_mk_a)	   \
196 		        : (n & 16 ? &tt_mfp.int_mk_b : &mfp.int_mk_b)),	   \
197 	     "m" (preempt_count()), "di" (HARDIRQ_OFFSET)		   \
198 );									   \
199 	for (;;);			/* fake noreturn */		   \
200 }
201 
202 BUILD_SLOW_IRQ(0);
203 BUILD_SLOW_IRQ(1);
204 BUILD_SLOW_IRQ(2);
205 BUILD_SLOW_IRQ(3);
206 BUILD_SLOW_IRQ(4);
207 BUILD_SLOW_IRQ(5);
208 BUILD_SLOW_IRQ(6);
209 BUILD_SLOW_IRQ(7);
210 BUILD_SLOW_IRQ(8);
211 BUILD_SLOW_IRQ(9);
212 BUILD_SLOW_IRQ(10);
213 BUILD_SLOW_IRQ(11);
214 BUILD_SLOW_IRQ(12);
215 BUILD_SLOW_IRQ(13);
216 BUILD_SLOW_IRQ(14);
217 BUILD_SLOW_IRQ(15);
218 BUILD_SLOW_IRQ(16);
219 BUILD_SLOW_IRQ(17);
220 BUILD_SLOW_IRQ(18);
221 BUILD_SLOW_IRQ(19);
222 BUILD_SLOW_IRQ(20);
223 BUILD_SLOW_IRQ(21);
224 BUILD_SLOW_IRQ(22);
225 BUILD_SLOW_IRQ(23);
226 BUILD_SLOW_IRQ(24);
227 BUILD_SLOW_IRQ(25);
228 BUILD_SLOW_IRQ(26);
229 BUILD_SLOW_IRQ(27);
230 BUILD_SLOW_IRQ(28);
231 BUILD_SLOW_IRQ(29);
232 BUILD_SLOW_IRQ(30);
233 BUILD_SLOW_IRQ(31);
234 
235 asm_irq_handler slow_handlers[32] = {
236 	[0]	= atari_slow_irq_0_handler,
237 	[1]	= atari_slow_irq_1_handler,
238 	[2]	= atari_slow_irq_2_handler,
239 	[3]	= atari_slow_irq_3_handler,
240 	[4]	= atari_slow_irq_4_handler,
241 	[5]	= atari_slow_irq_5_handler,
242 	[6]	= atari_slow_irq_6_handler,
243 	[7]	= atari_slow_irq_7_handler,
244 	[8]	= atari_slow_irq_8_handler,
245 	[9]	= atari_slow_irq_9_handler,
246 	[10]	= atari_slow_irq_10_handler,
247 	[11]	= atari_slow_irq_11_handler,
248 	[12]	= atari_slow_irq_12_handler,
249 	[13]	= atari_slow_irq_13_handler,
250 	[14]	= atari_slow_irq_14_handler,
251 	[15]	= atari_slow_irq_15_handler,
252 	[16]	= atari_slow_irq_16_handler,
253 	[17]	= atari_slow_irq_17_handler,
254 	[18]	= atari_slow_irq_18_handler,
255 	[19]	= atari_slow_irq_19_handler,
256 	[20]	= atari_slow_irq_20_handler,
257 	[21]	= atari_slow_irq_21_handler,
258 	[22]	= atari_slow_irq_22_handler,
259 	[23]	= atari_slow_irq_23_handler,
260 	[24]	= atari_slow_irq_24_handler,
261 	[25]	= atari_slow_irq_25_handler,
262 	[26]	= atari_slow_irq_26_handler,
263 	[27]	= atari_slow_irq_27_handler,
264 	[28]	= atari_slow_irq_28_handler,
265 	[29]	= atari_slow_irq_29_handler,
266 	[30]	= atari_slow_irq_30_handler,
267 	[31]	= atari_slow_irq_31_handler
268 };
269 
270 asmlinkage void atari_fast_irq_handler( void );
271 asmlinkage void atari_prio_irq_handler( void );
272 
273 /* Dummy function to allow asm with operands.  */
274 void atari_fast_prio_irq_dummy (void) {
275 __asm__ (__ALIGN_STR "\n"
276 "atari_fast_irq_handler:\n\t"
277 	"orw	#0x700,%%sr\n"		/* disable all interrupts */
278 "atari_prio_irq_handler:\n\t"
279 	"addl	%3,%2\n\t"		/* preempt_count() += HARDIRQ_OFFSET */
280 	SAVE_ALL_INT "\n\t"
281 	GET_CURRENT(%%d0) "\n\t"
282 	/* get vector number from stack frame and convert to source */
283 	"bfextu	%%sp@(%c1){#4,#10},%%d0\n\t"
284 	"subw	#(0x40-8),%%d0\n\t"
285 	"jpl	1f\n\t"
286 	"addw	#(0x40-8-0x18),%%d0\n"
287     "1:\tlea	%a0,%%a0\n\t"
288 	"addql	#1,%%a0@(%%d0:l:4)\n\t"
289 	"lea	irq_handler,%%a0\n\t"
290 	"lea	%%a0@(%%d0:l:8),%%a0\n\t"
291 	"pea	%%sp@\n\t"		/* push frame address */
292 	"movel	%%a0@(4),%%sp@-\n\t"	/* push handler data */
293 	"movel	%%d0,%%sp@-\n\t"	/* push int number */
294 	"movel	%%a0@,%%a0\n\t"
295 	"jsr	%%a0@\n\t"		/* and call the handler */
296 	"addql	#8,%%sp\n\t"
297 	"addql	#4,%%sp\n\t"
298 	"jbra	ret_from_interrupt"
299 	 : : "i" (&kstat_cpu(0).irqs), "n" (PT_OFF_FORMATVEC),
300 	     "m" (preempt_count()), "di" (HARDIRQ_OFFSET)
301 );
302 	for (;;);
303 }
304 
305 /* GK:
306  * HBL IRQ handler for Falcon. Nobody needs it :-)
307  * ++andreas: raise ipl to disable further HBLANK interrupts.
308  */
309 asmlinkage void falcon_hblhandler(void);
310 asm(".text\n"
311 __ALIGN_STR "\n\t"
312 "falcon_hblhandler:\n\t"
313 	"orw	#0x200,%sp@\n\t"	/* set saved ipl to 2 */
314 	"rte");
315 
316 /* Defined in entry.S; only increments 'num_spurious' */
317 asmlinkage void bad_interrupt(void);
318 
319 extern void atari_microwire_cmd( int cmd );
320 
321 extern int atari_SCC_reset_done;
322 
323 /*
324  * void atari_init_IRQ (void)
325  *
326  * Parameters:	None
327  *
328  * Returns:	Nothing
329  *
330  * This function should be called during kernel startup to initialize
331  * the atari IRQ handling routines.
332  */
333 
334 void __init atari_init_IRQ(void)
335 {
336 	int i;
337 
338 	/* initialize the vector table */
339 	for (i = 0; i < NUM_INT_SOURCES; ++i) {
340 		vectors[IRQ_SOURCE_TO_VECTOR(i)] = bad_interrupt;
341 	}
342 
343 	/* Initialize the MFP(s) */
344 
345 #ifdef ATARI_USE_SOFTWARE_EOI
346 	mfp.vec_adr  = 0x48;	/* Software EOI-Mode */
347 #else
348 	mfp.vec_adr  = 0x40;	/* Automatic EOI-Mode */
349 #endif
350 	mfp.int_en_a = 0x00;	/* turn off MFP-Ints */
351 	mfp.int_en_b = 0x00;
352 	mfp.int_mk_a = 0xff;	/* no Masking */
353 	mfp.int_mk_b = 0xff;
354 
355 	if (ATARIHW_PRESENT(TT_MFP)) {
356 #ifdef ATARI_USE_SOFTWARE_EOI
357 		tt_mfp.vec_adr  = 0x58;		/* Software EOI-Mode */
358 #else
359 		tt_mfp.vec_adr  = 0x50;		/* Automatic EOI-Mode */
360 #endif
361 		tt_mfp.int_en_a = 0x00;		/* turn off MFP-Ints */
362 		tt_mfp.int_en_b = 0x00;
363 		tt_mfp.int_mk_a = 0xff;		/* no Masking */
364 		tt_mfp.int_mk_b = 0xff;
365 	}
366 
367 	if (ATARIHW_PRESENT(SCC) && !atari_SCC_reset_done) {
368 		scc.cha_a_ctrl = 9;
369 		MFPDELAY();
370 		scc.cha_a_ctrl = (char) 0xc0; /* hardware reset */
371 	}
372 
373 	if (ATARIHW_PRESENT(SCU)) {
374 		/* init the SCU if present */
375 		tt_scu.sys_mask = 0x10;		/* enable VBL (for the cursor) and
376 									 * disable HSYNC interrupts (who
377 									 * needs them?)  MFP and SCC are
378 									 * enabled in VME mask
379 									 */
380 		tt_scu.vme_mask = 0x60;		/* enable MFP and SCC ints */
381 	}
382 	else {
383 		/* If no SCU and no Hades, the HSYNC interrupt needs to be
384 		 * disabled this way. (Else _inthandler in kernel/sys_call.S
385 		 * gets overruns)
386 		 */
387 
388 		if (!MACH_IS_HADES)
389 			vectors[VEC_INT2] = falcon_hblhandler;
390 	}
391 
392 	if (ATARIHW_PRESENT(PCM_8BIT) && ATARIHW_PRESENT(MICROWIRE)) {
393 		/* Initialize the LM1992 Sound Controller to enable
394 		   the PSG sound.  This is misplaced here, it should
395 		   be in an atasound_init(), that doesn't exist yet. */
396 		atari_microwire_cmd(MW_LM1992_PSG_HIGH);
397 	}
398 
399 	stdma_init();
400 
401 	/* Initialize the PSG: all sounds off, both ports output */
402 	sound_ym.rd_data_reg_sel = 7;
403 	sound_ym.wd_data = 0xff;
404 }
405 
406 
407 static irqreturn_t atari_call_irq_list( int irq, void *dev_id, struct pt_regs *fp )
408 {
409 	irq_node_t *node;
410 
411 	for (node = (irq_node_t *)dev_id; node; node = node->next)
412 		node->handler(irq, node->dev_id, fp);
413 	return IRQ_HANDLED;
414 }
415 
416 
417 /*
418  * atari_request_irq : add an interrupt service routine for a particular
419  *                     machine specific interrupt source.
420  *                     If the addition was successful, it returns 0.
421  */
422 
423 int atari_request_irq(unsigned int irq, irqreturn_t (*handler)(int, void *, struct pt_regs *),
424                       unsigned long flags, const char *devname, void *dev_id)
425 {
426 	int vector;
427 	unsigned long oflags = flags;
428 
429 	/*
430 	 * The following is a hack to make some PCI card drivers work,
431 	 * which set the SA_SHIRQ flag.
432 	 */
433 
434 	flags &= ~SA_SHIRQ;
435 
436 	if (flags == SA_INTERRUPT) {
437 		printk ("%s: SA_INTERRUPT changed to IRQ_TYPE_SLOW for %s\n",
438 			__FUNCTION__, devname);
439 		flags = IRQ_TYPE_SLOW;
440 	}
441 	if (flags < IRQ_TYPE_SLOW || flags > IRQ_TYPE_PRIO) {
442 		printk ("%s: Bad irq type 0x%lx <0x%lx> requested from %s\n",
443 		        __FUNCTION__, flags, oflags, devname);
444 		return -EINVAL;
445 	}
446 	if (!IS_VALID_INTNO(irq)) {
447 		printk ("%s: Unknown irq %d requested from %s\n",
448 		        __FUNCTION__, irq, devname);
449 		return -ENXIO;
450 	}
451 	vector = IRQ_SOURCE_TO_VECTOR(irq);
452 
453 	/*
454 	 * Check type/source combination: slow ints are (currently)
455 	 * only possible for MFP-interrupts.
456 	 */
457 	if (flags == IRQ_TYPE_SLOW &&
458 		(irq < STMFP_SOURCE_BASE || irq >= SCC_SOURCE_BASE)) {
459 		printk ("%s: Slow irq requested for non-MFP source %d from %s\n",
460 		        __FUNCTION__, irq, devname);
461 		return -EINVAL;
462 	}
463 
464 	if (vectors[vector] == bad_interrupt) {
465 		/* int has no handler yet */
466 		irq_handler[irq].handler = handler;
467 		irq_handler[irq].dev_id  = dev_id;
468 		irq_param[irq].flags   = flags;
469 		irq_param[irq].devname = devname;
470 		vectors[vector] =
471 			(flags == IRQ_TYPE_SLOW) ? slow_handlers[irq-STMFP_SOURCE_BASE] :
472 			(flags == IRQ_TYPE_FAST) ? atari_fast_irq_handler :
473 			                          atari_prio_irq_handler;
474 		/* If MFP int, also enable and umask it */
475 		atari_turnon_irq(irq);
476 		atari_enable_irq(irq);
477 
478 		return 0;
479 	}
480 	else if (irq_param[irq].flags == flags) {
481 		/* old handler is of same type -> handlers can be chained */
482 		irq_node_t *node;
483 		unsigned long flags;
484 
485 		local_irq_save(flags);
486 
487 		if (irq_handler[irq].handler != atari_call_irq_list) {
488 			/* Only one handler yet, make a node for this first one */
489 			if (!(node = new_irq_node()))
490 				return -ENOMEM;
491 			node->handler = irq_handler[irq].handler;
492 			node->dev_id  = irq_handler[irq].dev_id;
493 			node->devname = irq_param[irq].devname;
494 			node->next = NULL;
495 
496 			irq_handler[irq].handler = atari_call_irq_list;
497 			irq_handler[irq].dev_id  = node;
498 			irq_param[irq].devname   = "chained";
499 		}
500 
501 		if (!(node = new_irq_node()))
502 			return -ENOMEM;
503 		node->handler = handler;
504 		node->dev_id  = dev_id;
505 		node->devname = devname;
506 		/* new handlers are put in front of the queue */
507 		node->next = irq_handler[irq].dev_id;
508 		irq_handler[irq].dev_id = node;
509 
510 		local_irq_restore(flags);
511 		return 0;
512 	} else {
513 		printk ("%s: Irq %d allocated by other type int (call from %s)\n",
514 		        __FUNCTION__, irq, devname);
515 		return -EBUSY;
516 	}
517 }
518 
519 void atari_free_irq(unsigned int irq, void *dev_id)
520 {
521 	unsigned long flags;
522 	int vector;
523 	irq_node_t **list, *node;
524 
525 	if (!IS_VALID_INTNO(irq)) {
526 		printk("%s: Unknown irq %d\n", __FUNCTION__, irq);
527 		return;
528 	}
529 
530 	vector = IRQ_SOURCE_TO_VECTOR(irq);
531 	if (vectors[vector] == bad_interrupt)
532 		goto not_found;
533 
534 	local_irq_save(flags);
535 
536 	if (irq_handler[irq].handler != atari_call_irq_list) {
537 		/* It's the only handler for the interrupt */
538 		if (irq_handler[irq].dev_id != dev_id) {
539 			local_irq_restore(flags);
540 			goto not_found;
541 		}
542 		irq_handler[irq].handler = NULL;
543 		irq_handler[irq].dev_id  = NULL;
544 		irq_param[irq].devname   = NULL;
545 		vectors[vector] = bad_interrupt;
546 		/* If MFP int, also disable it */
547 		atari_disable_irq(irq);
548 		atari_turnoff_irq(irq);
549 
550 		local_irq_restore(flags);
551 		return;
552 	}
553 
554 	/* The interrupt is chained, find the irq on the list */
555 	for(list = (irq_node_t **)&irq_handler[irq].dev_id; *list; list = &(*list)->next) {
556 		if ((*list)->dev_id == dev_id) break;
557 	}
558 	if (!*list) {
559 		local_irq_restore(flags);
560 		goto not_found;
561 	}
562 
563 	(*list)->handler = NULL; /* Mark it as free for reallocation */
564 	*list = (*list)->next;
565 
566 	/* If there's now only one handler, unchain the interrupt, i.e. plug in
567 	 * the handler directly again and omit atari_call_irq_list */
568 	node = (irq_node_t *)irq_handler[irq].dev_id;
569 	if (node && !node->next) {
570 		irq_handler[irq].handler = node->handler;
571 		irq_handler[irq].dev_id  = node->dev_id;
572 		irq_param[irq].devname   = node->devname;
573 		node->handler = NULL; /* Mark it as free for reallocation */
574 	}
575 
576 	local_irq_restore(flags);
577 	return;
578 
579 not_found:
580 	printk("%s: tried to remove invalid irq\n", __FUNCTION__);
581 	return;
582 }
583 
584 
585 /*
586  * atari_register_vme_int() returns the number of a free interrupt vector for
587  * hardware with a programmable int vector (probably a VME board).
588  */
589 
590 unsigned long atari_register_vme_int(void)
591 {
592 	int i;
593 
594 	for(i = 0; i < 32; i++)
595 		if((free_vme_vec_bitmap & (1 << i)) == 0)
596 			break;
597 
598 	if(i == 16)
599 		return 0;
600 
601 	free_vme_vec_bitmap |= 1 << i;
602 	return (VME_SOURCE_BASE + i);
603 }
604 
605 
606 void atari_unregister_vme_int(unsigned long irq)
607 {
608 	if(irq >= VME_SOURCE_BASE && irq < VME_SOURCE_BASE + VME_MAX_SOURCES) {
609 		irq -= VME_SOURCE_BASE;
610 		free_vme_vec_bitmap &= ~(1 << irq);
611 	}
612 }
613 
614 
615 int show_atari_interrupts(struct seq_file *p, void *v)
616 {
617 	int i;
618 
619 	for (i = 0; i < NUM_INT_SOURCES; ++i) {
620 		if (vectors[IRQ_SOURCE_TO_VECTOR(i)] == bad_interrupt)
621 			continue;
622 		if (i < STMFP_SOURCE_BASE)
623 			seq_printf(p, "auto %2d: %10u ",
624 				       i, kstat_cpu(0).irqs[i]);
625 		else
626 			seq_printf(p, "vec $%02x: %10u ",
627 				       IRQ_SOURCE_TO_VECTOR(i),
628 				       kstat_cpu(0).irqs[i]);
629 
630 		if (irq_handler[i].handler != atari_call_irq_list) {
631 			seq_printf(p, "%s\n", irq_param[i].devname);
632 		}
633 		else {
634 			irq_node_t *n;
635 			for( n = (irq_node_t *)irq_handler[i].dev_id; n; n = n->next ) {
636 				seq_printf(p, "%s\n", n->devname);
637 				if (n->next)
638 					seq_puts(p, "                    " );
639 			}
640 		}
641 	}
642 	if (num_spurious)
643 		seq_printf(p, "spurio.: %10u\n", num_spurious);
644 
645 	return 0;
646 }
647 
648 
649