xref: /openbmc/linux/arch/m68k/mac/via.c (revision 8ee90c5c)
1 /*
2  *	6522 Versatile Interface Adapter (VIA)
3  *
4  *	There are two of these on the Mac II. Some IRQs are vectored
5  *	via them as are assorted bits and bobs - eg RTC, ADB.
6  *
7  * CSA: Motorola seems to have removed documentation on the 6522 from
8  * their web site; try
9  *     http://nerini.drf.com/vectrex/other/text/chips/6522/
10  *     http://www.zymurgy.net/classic/vic20/vicdet1.htm
11  * and
12  *     http://193.23.168.87/mikro_laborversuche/via_iobaustein/via6522_1.html
13  * for info.  A full-text web search on 6522 AND VIA will probably also
14  * net some usefulness. <cananian@alumni.princeton.edu> 20apr1999
15  *
16  * Additional data is here (the SY6522 was used in the Mac II etc):
17  *     http://www.6502.org/documents/datasheets/synertek/synertek_sy6522.pdf
18  *     http://www.6502.org/documents/datasheets/synertek/synertek_sy6522_programming_reference.pdf
19  *
20  * PRAM/RTC access algorithms are from the NetBSD RTC toolkit version 1.08b
21  * by Erik Vogan and adapted to Linux by Joshua M. Thompson (funaho@jurai.org)
22  *
23  */
24 
25 #include <linux/types.h>
26 #include <linux/kernel.h>
27 #include <linux/mm.h>
28 #include <linux/delay.h>
29 #include <linux/init.h>
30 #include <linux/module.h>
31 #include <linux/irq.h>
32 
33 #include <asm/macintosh.h>
34 #include <asm/macints.h>
35 #include <asm/mac_via.h>
36 #include <asm/mac_psc.h>
37 #include <asm/mac_oss.h>
38 
39 volatile __u8 *via1, *via2;
40 int rbv_present;
41 int via_alt_mapping;
42 EXPORT_SYMBOL(via_alt_mapping);
43 static __u8 rbv_clear;
44 
45 /*
46  * Globals for accessing the VIA chip registers without having to
47  * check if we're hitting a real VIA or an RBV. Normally you could
48  * just hit the combined register (ie, vIER|rIER) but that seems to
49  * break on AV Macs...probably because they actually decode more than
50  * eight address bits. Why can't Apple engineers at least be
51  * _consistently_ lazy?                          - 1999-05-21 (jmt)
52  */
53 
54 static int gIER,gIFR,gBufA,gBufB;
55 
56 /*
57  * Timer defs.
58  */
59 
60 #define TICK_SIZE		10000
61 #define MAC_CLOCK_TICK		(783300/HZ)		/* ticks per HZ */
62 #define MAC_CLOCK_LOW		(MAC_CLOCK_TICK&0xFF)
63 #define MAC_CLOCK_HIGH		(MAC_CLOCK_TICK>>8)
64 
65 
66 /*
67  * On Macs with a genuine VIA chip there is no way to mask an individual slot
68  * interrupt. This limitation also seems to apply to VIA clone logic cores in
69  * Quadra-like ASICs. (RBV and OSS machines don't have this limitation.)
70  *
71  * We used to fake it by configuring the relevant VIA pin as an output
72  * (to mask the interrupt) or input (to unmask). That scheme did not work on
73  * (at least) the Quadra 700. A NuBus card's /NMRQ signal is an open-collector
74  * circuit (see Designing Cards and Drivers for Macintosh II and Macintosh SE,
75  * p. 10-11 etc) but VIA outputs are not (see datasheet).
76  *
77  * Driving these outputs high must cause the VIA to source current and the
78  * card to sink current when it asserts /NMRQ. Current will flow but the pin
79  * voltage is uncertain and so the /NMRQ condition may still cause a transition
80  * at the VIA2 CA1 input (which explains the lost interrupts). A side effect
81  * is that a disabled slot IRQ can never be tested as pending or not.
82  *
83  * Driving these outputs low doesn't work either. All the slot /NMRQ lines are
84  * (active low) OR'd together to generate the CA1 (aka "SLOTS") interrupt (see
85  * The Guide To Macintosh Family Hardware, 2nd edition p. 167). If we drive a
86  * disabled /NMRQ line low, the falling edge immediately triggers a CA1
87  * interrupt and all slot interrupts after that will generate no transition
88  * and therefore no interrupt, even after being re-enabled.
89  *
90  * So we make the VIA port A I/O lines inputs and use nubus_disabled to keep
91  * track of their states. When any slot IRQ becomes disabled we mask the CA1
92  * umbrella interrupt. Only when all slot IRQs become enabled do we unmask
93  * the CA1 interrupt. It must remain enabled even when cards have no interrupt
94  * handler registered. Drivers must therefore disable a slot interrupt at the
95  * device before they call free_irq (like shared and autovector interrupts).
96  *
97  * There is also a related problem when MacOS is used to boot Linux. A network
98  * card brought up by a MacOS driver may raise an interrupt while Linux boots.
99  * This can be fatal since it can't be handled until the right driver loads
100  * (if such a driver exists at all). Apparently related to this hardware
101  * limitation, "Designing Cards and Drivers", p. 9-8, says that a slot
102  * interrupt with no driver would crash MacOS (the book was written before
103  * the appearance of Macs with RBV or OSS).
104  */
105 
106 static u8 nubus_disabled;
107 
108 void via_debug_dump(void);
109 static void via_nubus_init(void);
110 
111 /*
112  * Initialize the VIAs
113  *
114  * First we figure out where they actually _are_ as well as what type of
115  * VIA we have for VIA2 (it could be a real VIA or an RBV or even an OSS.)
116  * Then we pretty much clear them out and disable all IRQ sources.
117  */
118 
119 void __init via_init(void)
120 {
121 	via1 = (void *)VIA1_BASE;
122 	pr_debug("VIA1 detected at %p\n", via1);
123 
124 	if (oss_present) {
125 		via2 = NULL;
126 		rbv_present = 0;
127 	} else {
128 		switch (macintosh_config->via_type) {
129 
130 		/* IIci, IIsi, IIvx, IIvi (P6xx), LC series */
131 
132 		case MAC_VIA_IICI:
133 			via2 = (void *)RBV_BASE;
134 			pr_debug("VIA2 (RBV) detected at %p\n", via2);
135 			rbv_present = 1;
136 			if (macintosh_config->ident == MAC_MODEL_LCIII) {
137 				rbv_clear = 0x00;
138 			} else {
139 				/* on most RBVs (& unlike the VIAs), you   */
140 				/* need to set bit 7 when you write to IFR */
141 				/* in order for your clear to occur.       */
142 				rbv_clear = 0x80;
143 			}
144 			gIER = rIER;
145 			gIFR = rIFR;
146 			gBufA = rSIFR;
147 			gBufB = rBufB;
148 			break;
149 
150 		/* Quadra and early MacIIs agree on the VIA locations */
151 
152 		case MAC_VIA_QUADRA:
153 		case MAC_VIA_II:
154 			via2 = (void *) VIA2_BASE;
155 			pr_debug("VIA2 detected at %p\n", via2);
156 			rbv_present = 0;
157 			rbv_clear = 0x00;
158 			gIER = vIER;
159 			gIFR = vIFR;
160 			gBufA = vBufA;
161 			gBufB = vBufB;
162 			break;
163 
164 		default:
165 			panic("UNKNOWN VIA TYPE");
166 		}
167 	}
168 
169 #ifdef DEBUG_VIA
170 	via_debug_dump();
171 #endif
172 
173 	/*
174 	 * Shut down all IRQ sources, reset the timers, and
175 	 * kill the timer latch on VIA1.
176 	 */
177 
178 	via1[vIER] = 0x7F;
179 	via1[vIFR] = 0x7F;
180 	via1[vT1LL] = 0;
181 	via1[vT1LH] = 0;
182 	via1[vT1CL] = 0;
183 	via1[vT1CH] = 0;
184 	via1[vT2CL] = 0;
185 	via1[vT2CH] = 0;
186 	via1[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
187 	via1[vACR] &= ~0x03; /* disable port A & B latches */
188 
189 	/*
190 	 * SE/30: disable video IRQ
191 	 * XXX: testing for SE/30 VBL
192 	 */
193 
194 	if (macintosh_config->ident == MAC_MODEL_SE30) {
195 		via1[vDirB] |= 0x40;
196 		via1[vBufB] |= 0x40;
197 	}
198 
199 	/*
200 	 * Set the RTC bits to a known state: all lines to outputs and
201 	 * RTC disabled (yes that's 0 to enable and 1 to disable).
202 	 */
203 
204 	via1[vDirB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk | VIA1B_vRTCData);
205 	via1[vBufB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk);
206 
207 	/* Everything below this point is VIA2/RBV only... */
208 
209 	if (oss_present)
210 		return;
211 
212 	if ((macintosh_config->via_type == MAC_VIA_QUADRA) &&
213 	    (macintosh_config->adb_type != MAC_ADB_PB1) &&
214 	    (macintosh_config->adb_type != MAC_ADB_PB2) &&
215 	    (macintosh_config->ident    != MAC_MODEL_C660) &&
216 	    (macintosh_config->ident    != MAC_MODEL_Q840)) {
217 		via_alt_mapping = 1;
218 		via1[vDirB] |= 0x40;
219 		via1[vBufB] &= ~0x40;
220 	} else {
221 		via_alt_mapping = 0;
222 	}
223 
224 	/*
225 	 * Now initialize VIA2. For RBV we just kill all interrupts;
226 	 * for a regular VIA we also reset the timers and stuff.
227 	 */
228 
229 	via2[gIER] = 0x7F;
230 	via2[gIFR] = 0x7F | rbv_clear;
231 	if (!rbv_present) {
232 		via2[vT1LL] = 0;
233 		via2[vT1LH] = 0;
234 		via2[vT1CL] = 0;
235 		via2[vT1CH] = 0;
236 		via2[vT2CL] = 0;
237 		via2[vT2CH] = 0;
238 		via2[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
239 		via2[vACR] &= ~0x03; /* disable port A & B latches */
240 	}
241 
242 	via_nubus_init();
243 
244 	/* Everything below this point is VIA2 only... */
245 
246 	if (rbv_present)
247 		return;
248 
249 	/*
250 	 * Set vPCR for control line interrupts.
251 	 *
252 	 * CA1 (SLOTS IRQ), CB1 (ASC IRQ): negative edge trigger.
253 	 *
254 	 * Macs with ESP SCSI have a negative edge triggered SCSI interrupt.
255 	 * Testing reveals that PowerBooks do too. However, the SE/30
256 	 * schematic diagram shows an active high NCR5380 IRQ line.
257 	 */
258 
259 	pr_debug("VIA2 vPCR is 0x%02X\n", via2[vPCR]);
260 	if (macintosh_config->via_type == MAC_VIA_II) {
261 		/* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, pos. edge */
262 		via2[vPCR] = 0x66;
263 	} else {
264 		/* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, neg. edge */
265 		via2[vPCR] = 0x22;
266 	}
267 }
268 
269 /*
270  * Start the 100 Hz clock
271  */
272 
273 void __init via_init_clock(irq_handler_t func)
274 {
275 	via1[vACR] |= 0x40;
276 	via1[vT1LL] = MAC_CLOCK_LOW;
277 	via1[vT1LH] = MAC_CLOCK_HIGH;
278 	via1[vT1CL] = MAC_CLOCK_LOW;
279 	via1[vT1CH] = MAC_CLOCK_HIGH;
280 
281 	if (request_irq(IRQ_MAC_TIMER_1, func, 0, "timer", func))
282 		pr_err("Couldn't register %s interrupt\n", "timer");
283 }
284 
285 /*
286  * Debugging dump, used in various places to see what's going on.
287  */
288 
289 void via_debug_dump(void)
290 {
291 	printk(KERN_DEBUG "VIA1: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
292 		(uint) via1[vDirA], (uint) via1[vDirB], (uint) via1[vACR]);
293 	printk(KERN_DEBUG "         PCR = 0x%02X  IFR = 0x%02X IER = 0x%02X\n",
294 		(uint) via1[vPCR], (uint) via1[vIFR], (uint) via1[vIER]);
295 	if (!via2)
296 		return;
297 	if (rbv_present) {
298 		printk(KERN_DEBUG "VIA2:  IFR = 0x%02X  IER = 0x%02X\n",
299 			(uint) via2[rIFR], (uint) via2[rIER]);
300 		printk(KERN_DEBUG "      SIFR = 0x%02X SIER = 0x%02X\n",
301 			(uint) via2[rSIFR], (uint) via2[rSIER]);
302 	} else {
303 		printk(KERN_DEBUG "VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
304 			(uint) via2[vDirA], (uint) via2[vDirB],
305 			(uint) via2[vACR]);
306 		printk(KERN_DEBUG "         PCR = 0x%02X  IFR = 0x%02X IER = 0x%02X\n",
307 			(uint) via2[vPCR],
308 			(uint) via2[vIFR], (uint) via2[vIER]);
309 	}
310 }
311 
312 /*
313  * This is always executed with interrupts disabled.
314  *
315  * TBI: get time offset between scheduling timer ticks
316  */
317 
318 u32 mac_gettimeoffset(void)
319 {
320 	unsigned long ticks, offset = 0;
321 
322 	/* read VIA1 timer 2 current value */
323 	ticks = via1[vT1CL] | (via1[vT1CH] << 8);
324 	/* The probability of underflow is less than 2% */
325 	if (ticks > MAC_CLOCK_TICK - MAC_CLOCK_TICK / 50)
326 		/* Check for pending timer interrupt in VIA1 IFR */
327 		if (via1[vIFR] & 0x40) offset = TICK_SIZE;
328 
329 	ticks = MAC_CLOCK_TICK - ticks;
330 	ticks = ticks * 10000L / MAC_CLOCK_TICK;
331 
332 	return (ticks + offset) * 1000;
333 }
334 
335 /*
336  * Flush the L2 cache on Macs that have it by flipping
337  * the system into 24-bit mode for an instant.
338  */
339 
340 void via_flush_cache(void)
341 {
342 	via2[gBufB] &= ~VIA2B_vMode32;
343 	via2[gBufB] |= VIA2B_vMode32;
344 }
345 
346 /*
347  * Return the status of the L2 cache on a IIci
348  */
349 
350 int via_get_cache_disable(void)
351 {
352 	/* Safeguard against being called accidentally */
353 	if (!via2) {
354 		printk(KERN_ERR "via_get_cache_disable called on a non-VIA machine!\n");
355 		return 1;
356 	}
357 
358 	return (int) via2[gBufB] & VIA2B_vCDis;
359 }
360 
361 /*
362  * Initialize VIA2 for Nubus access
363  */
364 
365 static void __init via_nubus_init(void)
366 {
367 	/* unlock nubus transactions */
368 
369 	if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
370 	    (macintosh_config->adb_type != MAC_ADB_PB2)) {
371 		/* set the line to be an output on non-RBV machines */
372 		if (!rbv_present)
373 			via2[vDirB] |= 0x02;
374 
375 		/* this seems to be an ADB bit on PMU machines */
376 		/* according to MkLinux.  -- jmt               */
377 		via2[gBufB] |= 0x02;
378 	}
379 
380 	/*
381 	 * Disable the slot interrupts. On some hardware that's not possible.
382 	 * On some hardware it's unclear what all of these I/O lines do.
383 	 */
384 
385 	switch (macintosh_config->via_type) {
386 	case MAC_VIA_II:
387 	case MAC_VIA_QUADRA:
388 		pr_debug("VIA2 vDirA is 0x%02X\n", via2[vDirA]);
389 		break;
390 	case MAC_VIA_IICI:
391 		/* RBV. Disable all the slot interrupts. SIER works like IER. */
392 		via2[rSIER] = 0x7F;
393 		break;
394 	}
395 }
396 
397 void via_nubus_irq_startup(int irq)
398 {
399 	int irq_idx = IRQ_IDX(irq);
400 
401 	switch (macintosh_config->via_type) {
402 	case MAC_VIA_II:
403 	case MAC_VIA_QUADRA:
404 		/* Make the port A line an input. Probably redundant. */
405 		if (macintosh_config->via_type == MAC_VIA_II) {
406 			/* The top two bits are RAM size outputs. */
407 			via2[vDirA] &= 0xC0 | ~(1 << irq_idx);
408 		} else {
409 			/* Allow NuBus slots 9 through F. */
410 			via2[vDirA] &= 0x80 | ~(1 << irq_idx);
411 		}
412 		/* fall through */
413 	case MAC_VIA_IICI:
414 		via_irq_enable(irq);
415 		break;
416 	}
417 }
418 
419 void via_nubus_irq_shutdown(int irq)
420 {
421 	switch (macintosh_config->via_type) {
422 	case MAC_VIA_II:
423 	case MAC_VIA_QUADRA:
424 		/* Ensure that the umbrella CA1 interrupt remains enabled. */
425 		via_irq_enable(irq);
426 		break;
427 	case MAC_VIA_IICI:
428 		via_irq_disable(irq);
429 		break;
430 	}
431 }
432 
433 /*
434  * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
435  * via6522.c :-), disable/pending masks added.
436  */
437 
438 void via1_irq(struct irq_desc *desc)
439 {
440 	int irq_num;
441 	unsigned char irq_bit, events;
442 
443 	events = via1[vIFR] & via1[vIER] & 0x7F;
444 	if (!events)
445 		return;
446 
447 	irq_num = VIA1_SOURCE_BASE;
448 	irq_bit = 1;
449 	do {
450 		if (events & irq_bit) {
451 			via1[vIFR] = irq_bit;
452 			generic_handle_irq(irq_num);
453 		}
454 		++irq_num;
455 		irq_bit <<= 1;
456 	} while (events >= irq_bit);
457 }
458 
459 static void via2_irq(struct irq_desc *desc)
460 {
461 	int irq_num;
462 	unsigned char irq_bit, events;
463 
464 	events = via2[gIFR] & via2[gIER] & 0x7F;
465 	if (!events)
466 		return;
467 
468 	irq_num = VIA2_SOURCE_BASE;
469 	irq_bit = 1;
470 	do {
471 		if (events & irq_bit) {
472 			via2[gIFR] = irq_bit | rbv_clear;
473 			generic_handle_irq(irq_num);
474 		}
475 		++irq_num;
476 		irq_bit <<= 1;
477 	} while (events >= irq_bit);
478 }
479 
480 /*
481  * Dispatch Nubus interrupts. We are called as a secondary dispatch by the
482  * VIA2 dispatcher as a fast interrupt handler.
483  */
484 
485 static void via_nubus_irq(struct irq_desc *desc)
486 {
487 	int slot_irq;
488 	unsigned char slot_bit, events;
489 
490 	events = ~via2[gBufA] & 0x7F;
491 	if (rbv_present)
492 		events &= via2[rSIER];
493 	else
494 		events &= ~via2[vDirA];
495 	if (!events)
496 		return;
497 
498 	do {
499 		slot_irq = IRQ_NUBUS_F;
500 		slot_bit = 0x40;
501 		do {
502 			if (events & slot_bit) {
503 				events &= ~slot_bit;
504 				generic_handle_irq(slot_irq);
505 			}
506 			--slot_irq;
507 			slot_bit >>= 1;
508 		} while (events);
509 
510  		/* clear the CA1 interrupt and make certain there's no more. */
511 		via2[gIFR] = 0x02 | rbv_clear;
512 		events = ~via2[gBufA] & 0x7F;
513 		if (rbv_present)
514 			events &= via2[rSIER];
515 		else
516 			events &= ~via2[vDirA];
517 	} while (events);
518 }
519 
520 /*
521  * Register the interrupt dispatchers for VIA or RBV machines only.
522  */
523 
524 void __init via_register_interrupts(void)
525 {
526 	if (via_alt_mapping) {
527 		/* software interrupt */
528 		irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
529 		/* via1 interrupt */
530 		irq_set_chained_handler(IRQ_AUTO_6, via1_irq);
531 	} else {
532 		irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
533 	}
534 	irq_set_chained_handler(IRQ_AUTO_2, via2_irq);
535 	irq_set_chained_handler(IRQ_MAC_NUBUS, via_nubus_irq);
536 }
537 
538 void via_irq_enable(int irq) {
539 	int irq_src	= IRQ_SRC(irq);
540 	int irq_idx	= IRQ_IDX(irq);
541 
542 	if (irq_src == 1) {
543 		via1[vIER] = IER_SET_BIT(irq_idx);
544 	} else if (irq_src == 2) {
545 		if (irq != IRQ_MAC_NUBUS || nubus_disabled == 0)
546 			via2[gIER] = IER_SET_BIT(irq_idx);
547 	} else if (irq_src == 7) {
548 		switch (macintosh_config->via_type) {
549 		case MAC_VIA_II:
550 		case MAC_VIA_QUADRA:
551 			nubus_disabled &= ~(1 << irq_idx);
552 			/* Enable the CA1 interrupt when no slot is disabled. */
553 			if (!nubus_disabled)
554 				via2[gIER] = IER_SET_BIT(1);
555 			break;
556 		case MAC_VIA_IICI:
557 			/* On RBV, enable the slot interrupt.
558 			 * SIER works like IER.
559 			 */
560 			via2[rSIER] = IER_SET_BIT(irq_idx);
561 			break;
562 		}
563 	}
564 }
565 
566 void via_irq_disable(int irq) {
567 	int irq_src	= IRQ_SRC(irq);
568 	int irq_idx	= IRQ_IDX(irq);
569 
570 	if (irq_src == 1) {
571 		via1[vIER] = IER_CLR_BIT(irq_idx);
572 	} else if (irq_src == 2) {
573 		via2[gIER] = IER_CLR_BIT(irq_idx);
574 	} else if (irq_src == 7) {
575 		switch (macintosh_config->via_type) {
576 		case MAC_VIA_II:
577 		case MAC_VIA_QUADRA:
578 			nubus_disabled |= 1 << irq_idx;
579 			if (nubus_disabled)
580 				via2[gIER] = IER_CLR_BIT(1);
581 			break;
582 		case MAC_VIA_IICI:
583 			via2[rSIER] = IER_CLR_BIT(irq_idx);
584 			break;
585 		}
586 	}
587 }
588 
589 void via1_set_head(int head)
590 {
591 	if (head == 0)
592 		via1[vBufA] &= ~VIA1A_vHeadSel;
593 	else
594 		via1[vBufA] |= VIA1A_vHeadSel;
595 }
596 EXPORT_SYMBOL(via1_set_head);
597 
598 int via2_scsi_drq_pending(void)
599 {
600 	return via2[gIFR] & (1 << IRQ_IDX(IRQ_MAC_SCSIDRQ));
601 }
602 EXPORT_SYMBOL(via2_scsi_drq_pending);
603