1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * 6522 Versatile Interface Adapter (VIA)
4 *
5 * There are two of these on the Mac II. Some IRQs are vectored
6 * via them as are assorted bits and bobs - eg RTC, ADB.
7 *
8 * CSA: Motorola seems to have removed documentation on the 6522 from
9 * their web site; try
10 * http://nerini.drf.com/vectrex/other/text/chips/6522/
11 * http://www.zymurgy.net/classic/vic20/vicdet1.htm
12 * and
13 * http://193.23.168.87/mikro_laborversuche/via_iobaustein/via6522_1.html
14 * for info. A full-text web search on 6522 AND VIA will probably also
15 * net some usefulness. <cananian@alumni.princeton.edu> 20apr1999
16 *
17 * Additional data is here (the SY6522 was used in the Mac II etc):
18 * http://www.6502.org/documents/datasheets/synertek/synertek_sy6522.pdf
19 * http://www.6502.org/documents/datasheets/synertek/synertek_sy6522_programming_reference.pdf
20 *
21 * PRAM/RTC access algorithms are from the NetBSD RTC toolkit version 1.08b
22 * by Erik Vogan and adapted to Linux by Joshua M. Thompson (funaho@jurai.org)
23 *
24 */
25
26 #include <linux/types.h>
27 #include <linux/kernel.h>
28 #include <linux/mm.h>
29 #include <linux/delay.h>
30 #include <linux/init.h>
31 #include <linux/module.h>
32 #include <linux/irq.h>
33
34 #include <asm/macintosh.h>
35 #include <asm/macints.h>
36 #include <asm/mac_via.h>
37 #include <asm/mac_psc.h>
38 #include <asm/mac_oss.h>
39
40 volatile __u8 *via1, *via2;
41 int rbv_present;
42 int via_alt_mapping;
43 EXPORT_SYMBOL(via_alt_mapping);
44 static __u8 rbv_clear;
45
46 /*
47 * Globals for accessing the VIA chip registers without having to
48 * check if we're hitting a real VIA or an RBV. Normally you could
49 * just hit the combined register (ie, vIER|rIER) but that seems to
50 * break on AV Macs...probably because they actually decode more than
51 * eight address bits. Why can't Apple engineers at least be
52 * _consistently_ lazy? - 1999-05-21 (jmt)
53 */
54
55 static int gIER,gIFR,gBufA,gBufB;
56
57 /*
58 * On Macs with a genuine VIA chip there is no way to mask an individual slot
59 * interrupt. This limitation also seems to apply to VIA clone logic cores in
60 * Quadra-like ASICs. (RBV and OSS machines don't have this limitation.)
61 *
62 * We used to fake it by configuring the relevant VIA pin as an output
63 * (to mask the interrupt) or input (to unmask). That scheme did not work on
64 * (at least) the Quadra 700. A NuBus card's /NMRQ signal is an open-collector
65 * circuit (see Designing Cards and Drivers for Macintosh II and Macintosh SE,
66 * p. 10-11 etc) but VIA outputs are not (see datasheet).
67 *
68 * Driving these outputs high must cause the VIA to source current and the
69 * card to sink current when it asserts /NMRQ. Current will flow but the pin
70 * voltage is uncertain and so the /NMRQ condition may still cause a transition
71 * at the VIA2 CA1 input (which explains the lost interrupts). A side effect
72 * is that a disabled slot IRQ can never be tested as pending or not.
73 *
74 * Driving these outputs low doesn't work either. All the slot /NMRQ lines are
75 * (active low) OR'd together to generate the CA1 (aka "SLOTS") interrupt (see
76 * The Guide To Macintosh Family Hardware, 2nd edition p. 167). If we drive a
77 * disabled /NMRQ line low, the falling edge immediately triggers a CA1
78 * interrupt and all slot interrupts after that will generate no transition
79 * and therefore no interrupt, even after being re-enabled.
80 *
81 * So we make the VIA port A I/O lines inputs and use nubus_disabled to keep
82 * track of their states. When any slot IRQ becomes disabled we mask the CA1
83 * umbrella interrupt. Only when all slot IRQs become enabled do we unmask
84 * the CA1 interrupt. It must remain enabled even when cards have no interrupt
85 * handler registered. Drivers must therefore disable a slot interrupt at the
86 * device before they call free_irq (like shared and autovector interrupts).
87 *
88 * There is also a related problem when MacOS is used to boot Linux. A network
89 * card brought up by a MacOS driver may raise an interrupt while Linux boots.
90 * This can be fatal since it can't be handled until the right driver loads
91 * (if such a driver exists at all). Apparently related to this hardware
92 * limitation, "Designing Cards and Drivers", p. 9-8, says that a slot
93 * interrupt with no driver would crash MacOS (the book was written before
94 * the appearance of Macs with RBV or OSS).
95 */
96
97 static u8 nubus_disabled;
98
99 void via_debug_dump(void);
100 static void via_nubus_init(void);
101
102 /*
103 * Initialize the VIAs
104 *
105 * First we figure out where they actually _are_ as well as what type of
106 * VIA we have for VIA2 (it could be a real VIA or an RBV or even an OSS.)
107 * Then we pretty much clear them out and disable all IRQ sources.
108 */
109
via_init(void)110 void __init via_init(void)
111 {
112 via1 = (void *)VIA1_BASE;
113 pr_debug("VIA1 detected at %p\n", via1);
114
115 if (oss_present) {
116 via2 = NULL;
117 rbv_present = 0;
118 } else {
119 switch (macintosh_config->via_type) {
120
121 /* IIci, IIsi, IIvx, IIvi (P6xx), LC series */
122
123 case MAC_VIA_IICI:
124 via2 = (void *)RBV_BASE;
125 pr_debug("VIA2 (RBV) detected at %p\n", via2);
126 rbv_present = 1;
127 if (macintosh_config->ident == MAC_MODEL_LCIII) {
128 rbv_clear = 0x00;
129 } else {
130 /* on most RBVs (& unlike the VIAs), you */
131 /* need to set bit 7 when you write to IFR */
132 /* in order for your clear to occur. */
133 rbv_clear = 0x80;
134 }
135 gIER = rIER;
136 gIFR = rIFR;
137 gBufA = rSIFR;
138 gBufB = rBufB;
139 break;
140
141 /* Quadra and early MacIIs agree on the VIA locations */
142
143 case MAC_VIA_QUADRA:
144 case MAC_VIA_II:
145 via2 = (void *) VIA2_BASE;
146 pr_debug("VIA2 detected at %p\n", via2);
147 rbv_present = 0;
148 rbv_clear = 0x00;
149 gIER = vIER;
150 gIFR = vIFR;
151 gBufA = vBufA;
152 gBufB = vBufB;
153 break;
154
155 default:
156 panic("UNKNOWN VIA TYPE");
157 }
158 }
159
160 #ifdef DEBUG_VIA
161 via_debug_dump();
162 #endif
163
164 /*
165 * Shut down all IRQ sources, reset the timers, and
166 * kill the timer latch on VIA1.
167 */
168
169 via1[vIER] = 0x7F;
170 via1[vIFR] = 0x7F;
171 via1[vT1LL] = 0;
172 via1[vT1LH] = 0;
173 via1[vT1CL] = 0;
174 via1[vT1CH] = 0;
175 via1[vT2CL] = 0;
176 via1[vT2CH] = 0;
177 via1[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
178 via1[vACR] &= ~0x03; /* disable port A & B latches */
179
180 /*
181 * SE/30: disable video IRQ
182 * XXX: testing for SE/30 VBL
183 */
184
185 if (macintosh_config->ident == MAC_MODEL_SE30) {
186 via1[vDirB] |= 0x40;
187 via1[vBufB] |= 0x40;
188 }
189
190 /*
191 * Set the RTC bits to a known state: all lines to outputs and
192 * RTC disabled (yes that's 0 to enable and 1 to disable).
193 */
194
195 via1[vDirB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk | VIA1B_vRTCData);
196 via1[vBufB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk);
197
198 /* Everything below this point is VIA2/RBV only... */
199
200 if (oss_present)
201 return;
202
203 if ((macintosh_config->via_type == MAC_VIA_QUADRA) &&
204 (macintosh_config->adb_type != MAC_ADB_PB1) &&
205 (macintosh_config->adb_type != MAC_ADB_PB2) &&
206 (macintosh_config->ident != MAC_MODEL_C660) &&
207 (macintosh_config->ident != MAC_MODEL_Q840)) {
208 via_alt_mapping = 1;
209 via1[vDirB] |= 0x40;
210 via1[vBufB] &= ~0x40;
211 } else {
212 via_alt_mapping = 0;
213 }
214
215 /*
216 * Now initialize VIA2. For RBV we just kill all interrupts;
217 * for a regular VIA we also reset the timers and stuff.
218 */
219
220 via2[gIER] = 0x7F;
221 via2[gIFR] = 0x7F | rbv_clear;
222 if (!rbv_present) {
223 via2[vT1LL] = 0;
224 via2[vT1LH] = 0;
225 via2[vT1CL] = 0;
226 via2[vT1CH] = 0;
227 via2[vT2CL] = 0;
228 via2[vT2CH] = 0;
229 via2[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
230 via2[vACR] &= ~0x03; /* disable port A & B latches */
231 }
232
233 via_nubus_init();
234
235 /* Everything below this point is VIA2 only... */
236
237 if (rbv_present)
238 return;
239
240 /*
241 * Set vPCR for control line interrupts.
242 *
243 * CA1 (SLOTS IRQ), CB1 (ASC IRQ): negative edge trigger.
244 *
245 * Macs with ESP SCSI have a negative edge triggered SCSI interrupt.
246 * Testing reveals that PowerBooks do too. However, the SE/30
247 * schematic diagram shows an active high NCR5380 IRQ line.
248 */
249
250 pr_debug("VIA2 vPCR is 0x%02X\n", via2[vPCR]);
251 if (macintosh_config->via_type == MAC_VIA_II) {
252 /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, pos. edge */
253 via2[vPCR] = 0x66;
254 } else {
255 /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, neg. edge */
256 via2[vPCR] = 0x22;
257 }
258 }
259
260 /*
261 * Debugging dump, used in various places to see what's going on.
262 */
263
via_debug_dump(void)264 void via_debug_dump(void)
265 {
266 printk(KERN_DEBUG "VIA1: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
267 (uint) via1[vDirA], (uint) via1[vDirB], (uint) via1[vACR]);
268 printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
269 (uint) via1[vPCR], (uint) via1[vIFR], (uint) via1[vIER]);
270 if (!via2)
271 return;
272 if (rbv_present) {
273 printk(KERN_DEBUG "VIA2: IFR = 0x%02X IER = 0x%02X\n",
274 (uint) via2[rIFR], (uint) via2[rIER]);
275 printk(KERN_DEBUG " SIFR = 0x%02X SIER = 0x%02X\n",
276 (uint) via2[rSIFR], (uint) via2[rSIER]);
277 } else {
278 printk(KERN_DEBUG "VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
279 (uint) via2[vDirA], (uint) via2[vDirB],
280 (uint) via2[vACR]);
281 printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
282 (uint) via2[vPCR],
283 (uint) via2[vIFR], (uint) via2[vIER]);
284 }
285 }
286
287 /*
288 * Flush the L2 cache on Macs that have it by flipping
289 * the system into 24-bit mode for an instant.
290 */
291
via_l2_flush(int writeback)292 void via_l2_flush(int writeback)
293 {
294 unsigned long flags;
295
296 local_irq_save(flags);
297 via2[gBufB] &= ~VIA2B_vMode32;
298 via2[gBufB] |= VIA2B_vMode32;
299 local_irq_restore(flags);
300 }
301
302 /*
303 * Return the status of the L2 cache on a IIci
304 */
305
via_get_cache_disable(void)306 int via_get_cache_disable(void)
307 {
308 /* Safeguard against being called accidentally */
309 if (!via2) {
310 printk(KERN_ERR "via_get_cache_disable called on a non-VIA machine!\n");
311 return 1;
312 }
313
314 return (int) via2[gBufB] & VIA2B_vCDis;
315 }
316
317 /*
318 * Initialize VIA2 for Nubus access
319 */
320
via_nubus_init(void)321 static void __init via_nubus_init(void)
322 {
323 /* unlock nubus transactions */
324
325 if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
326 (macintosh_config->adb_type != MAC_ADB_PB2)) {
327 /* set the line to be an output on non-RBV machines */
328 if (!rbv_present)
329 via2[vDirB] |= 0x02;
330
331 /* this seems to be an ADB bit on PMU machines */
332 /* according to MkLinux. -- jmt */
333 via2[gBufB] |= 0x02;
334 }
335
336 /*
337 * Disable the slot interrupts. On some hardware that's not possible.
338 * On some hardware it's unclear what all of these I/O lines do.
339 */
340
341 switch (macintosh_config->via_type) {
342 case MAC_VIA_II:
343 case MAC_VIA_QUADRA:
344 pr_debug("VIA2 vDirA is 0x%02X\n", via2[vDirA]);
345 break;
346 case MAC_VIA_IICI:
347 /* RBV. Disable all the slot interrupts. SIER works like IER. */
348 via2[rSIER] = 0x7F;
349 break;
350 }
351 }
352
via_nubus_irq_startup(int irq)353 void via_nubus_irq_startup(int irq)
354 {
355 int irq_idx = IRQ_IDX(irq);
356
357 switch (macintosh_config->via_type) {
358 case MAC_VIA_II:
359 case MAC_VIA_QUADRA:
360 /* Make the port A line an input. Probably redundant. */
361 if (macintosh_config->via_type == MAC_VIA_II) {
362 /* The top two bits are RAM size outputs. */
363 via2[vDirA] &= 0xC0 | ~(1 << irq_idx);
364 } else {
365 /* Allow NuBus slots 9 through F. */
366 via2[vDirA] &= 0x80 | ~(1 << irq_idx);
367 }
368 /* fall through */
369 case MAC_VIA_IICI:
370 via_irq_enable(irq);
371 break;
372 }
373 }
374
via_nubus_irq_shutdown(int irq)375 void via_nubus_irq_shutdown(int irq)
376 {
377 switch (macintosh_config->via_type) {
378 case MAC_VIA_II:
379 case MAC_VIA_QUADRA:
380 /* Ensure that the umbrella CA1 interrupt remains enabled. */
381 via_irq_enable(irq);
382 break;
383 case MAC_VIA_IICI:
384 via_irq_disable(irq);
385 break;
386 }
387 }
388
389 /*
390 * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
391 * via6522.c :-), disable/pending masks added.
392 */
393
394 #define VIA_TIMER_1_INT BIT(6)
395
via1_irq(struct irq_desc * desc)396 void via1_irq(struct irq_desc *desc)
397 {
398 int irq_num;
399 unsigned char irq_bit, events;
400
401 events = via1[vIFR] & via1[vIER] & 0x7F;
402 if (!events)
403 return;
404
405 irq_num = IRQ_MAC_TIMER_1;
406 irq_bit = VIA_TIMER_1_INT;
407 if (events & irq_bit) {
408 unsigned long flags;
409
410 local_irq_save(flags);
411 via1[vIFR] = irq_bit;
412 generic_handle_irq(irq_num);
413 local_irq_restore(flags);
414
415 events &= ~irq_bit;
416 if (!events)
417 return;
418 }
419
420 irq_num = VIA1_SOURCE_BASE;
421 irq_bit = 1;
422 do {
423 if (events & irq_bit) {
424 via1[vIFR] = irq_bit;
425 generic_handle_irq(irq_num);
426 }
427 ++irq_num;
428 irq_bit <<= 1;
429 } while (events >= irq_bit);
430 }
431
via2_irq(struct irq_desc * desc)432 static void via2_irq(struct irq_desc *desc)
433 {
434 int irq_num;
435 unsigned char irq_bit, events;
436
437 events = via2[gIFR] & via2[gIER] & 0x7F;
438 if (!events)
439 return;
440
441 irq_num = VIA2_SOURCE_BASE;
442 irq_bit = 1;
443 do {
444 if (events & irq_bit) {
445 via2[gIFR] = irq_bit | rbv_clear;
446 generic_handle_irq(irq_num);
447 }
448 ++irq_num;
449 irq_bit <<= 1;
450 } while (events >= irq_bit);
451 }
452
453 /*
454 * Dispatch Nubus interrupts. We are called as a secondary dispatch by the
455 * VIA2 dispatcher as a fast interrupt handler.
456 */
457
via_nubus_irq(struct irq_desc * desc)458 static void via_nubus_irq(struct irq_desc *desc)
459 {
460 int slot_irq;
461 unsigned char slot_bit, events;
462
463 events = ~via2[gBufA] & 0x7F;
464 if (rbv_present)
465 events &= via2[rSIER];
466 else
467 events &= ~via2[vDirA];
468 if (!events)
469 return;
470
471 do {
472 slot_irq = IRQ_NUBUS_F;
473 slot_bit = 0x40;
474 do {
475 if (events & slot_bit) {
476 events &= ~slot_bit;
477 generic_handle_irq(slot_irq);
478 }
479 --slot_irq;
480 slot_bit >>= 1;
481 } while (events);
482
483 /* clear the CA1 interrupt and make certain there's no more. */
484 via2[gIFR] = 0x02 | rbv_clear;
485 events = ~via2[gBufA] & 0x7F;
486 if (rbv_present)
487 events &= via2[rSIER];
488 else
489 events &= ~via2[vDirA];
490 } while (events);
491 }
492
493 /*
494 * Register the interrupt dispatchers for VIA or RBV machines only.
495 */
496
via_register_interrupts(void)497 void __init via_register_interrupts(void)
498 {
499 if (via_alt_mapping) {
500 /* software interrupt */
501 irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
502 /* via1 interrupt */
503 irq_set_chained_handler(IRQ_AUTO_6, via1_irq);
504 } else {
505 irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
506 }
507 irq_set_chained_handler(IRQ_AUTO_2, via2_irq);
508 irq_set_chained_handler(IRQ_MAC_NUBUS, via_nubus_irq);
509 }
510
via_irq_enable(int irq)511 void via_irq_enable(int irq) {
512 int irq_src = IRQ_SRC(irq);
513 int irq_idx = IRQ_IDX(irq);
514
515 if (irq_src == 1) {
516 via1[vIER] = IER_SET_BIT(irq_idx);
517 } else if (irq_src == 2) {
518 if (irq != IRQ_MAC_NUBUS || nubus_disabled == 0)
519 via2[gIER] = IER_SET_BIT(irq_idx);
520 } else if (irq_src == 7) {
521 switch (macintosh_config->via_type) {
522 case MAC_VIA_II:
523 case MAC_VIA_QUADRA:
524 nubus_disabled &= ~(1 << irq_idx);
525 /* Enable the CA1 interrupt when no slot is disabled. */
526 if (!nubus_disabled)
527 via2[gIER] = IER_SET_BIT(1);
528 break;
529 case MAC_VIA_IICI:
530 /* On RBV, enable the slot interrupt.
531 * SIER works like IER.
532 */
533 via2[rSIER] = IER_SET_BIT(irq_idx);
534 break;
535 }
536 }
537 }
538
via_irq_disable(int irq)539 void via_irq_disable(int irq) {
540 int irq_src = IRQ_SRC(irq);
541 int irq_idx = IRQ_IDX(irq);
542
543 if (irq_src == 1) {
544 via1[vIER] = IER_CLR_BIT(irq_idx);
545 } else if (irq_src == 2) {
546 via2[gIER] = IER_CLR_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 if (nubus_disabled)
553 via2[gIER] = IER_CLR_BIT(1);
554 break;
555 case MAC_VIA_IICI:
556 via2[rSIER] = IER_CLR_BIT(irq_idx);
557 break;
558 }
559 }
560 }
561
via1_set_head(int head)562 void via1_set_head(int head)
563 {
564 if (head == 0)
565 via1[vBufA] &= ~VIA1A_vHeadSel;
566 else
567 via1[vBufA] |= VIA1A_vHeadSel;
568 }
569 EXPORT_SYMBOL(via1_set_head);
570
via2_scsi_drq_pending(void)571 int via2_scsi_drq_pending(void)
572 {
573 return via2[gIFR] & (1 << IRQ_IDX(IRQ_MAC_SCSIDRQ));
574 }
575 EXPORT_SYMBOL(via2_scsi_drq_pending);
576
577 /* timer and clock source */
578
579 #define VIA_CLOCK_FREQ 783360 /* VIA "phase 2" clock in Hz */
580 #define VIA_TIMER_INTERVAL (1000000 / HZ) /* microseconds per jiffy */
581 #define VIA_TIMER_CYCLES (VIA_CLOCK_FREQ / HZ) /* clock cycles per jiffy */
582
583 #define VIA_TC (VIA_TIMER_CYCLES - 2) /* including 0 and -1 */
584 #define VIA_TC_LOW (VIA_TC & 0xFF)
585 #define VIA_TC_HIGH (VIA_TC >> 8)
586
via_init_clock(irq_handler_t timer_routine)587 void __init via_init_clock(irq_handler_t timer_routine)
588 {
589 if (request_irq(IRQ_MAC_TIMER_1, timer_routine, 0, "timer", NULL)) {
590 pr_err("Couldn't register %s interrupt\n", "timer");
591 return;
592 }
593
594 via1[vT1LL] = VIA_TC_LOW;
595 via1[vT1LH] = VIA_TC_HIGH;
596 via1[vT1CL] = VIA_TC_LOW;
597 via1[vT1CH] = VIA_TC_HIGH;
598 via1[vACR] |= 0x40;
599 }
600
mac_gettimeoffset(void)601 u32 mac_gettimeoffset(void)
602 {
603 unsigned long flags;
604 u8 count_high;
605 u16 count, offset = 0;
606
607 /*
608 * Timer counter wrap-around is detected with the timer interrupt flag
609 * but reading the counter low byte (vT1CL) would reset the flag.
610 * Also, accessing both counter registers is essentially a data race.
611 * These problems are avoided by ignoring the low byte. Clock accuracy
612 * is 256 times worse (error can reach 0.327 ms) but CPU overhead is
613 * reduced by avoiding slow VIA register accesses.
614 */
615
616 local_irq_save(flags);
617 count_high = via1[vT1CH];
618 if (count_high == 0xFF)
619 count_high = 0;
620 if (count_high > 0 && (via1[vIFR] & VIA_TIMER_1_INT))
621 offset = VIA_TIMER_CYCLES;
622 local_irq_restore(flags);
623
624 count = count_high << 8;
625 count = VIA_TIMER_CYCLES - count + offset;
626
627 return ((count * VIA_TIMER_INTERVAL) / VIA_TIMER_CYCLES) * 1000;
628 }
629