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/clocksource.h>
27 #include <linux/types.h>
28 #include <linux/kernel.h>
29 #include <linux/mm.h>
30 #include <linux/delay.h>
31 #include <linux/init.h>
32 #include <linux/module.h>
33 #include <linux/irq.h>
34
35 #include <asm/macintosh.h>
36 #include <asm/macints.h>
37 #include <asm/mac_via.h>
38 #include <asm/mac_psc.h>
39 #include <asm/mac_oss.h>
40
41 volatile __u8 *via1, *via2;
42 int rbv_present;
43 int via_alt_mapping;
44 EXPORT_SYMBOL(via_alt_mapping);
45 static __u8 rbv_clear;
46
47 /*
48 * Globals for accessing the VIA chip registers without having to
49 * check if we're hitting a real VIA or an RBV. Normally you could
50 * just hit the combined register (ie, vIER|rIER) but that seems to
51 * break on AV Macs...probably because they actually decode more than
52 * eight address bits. Why can't Apple engineers at least be
53 * _consistently_ lazy? - 1999-05-21 (jmt)
54 */
55
56 static int gIER,gIFR,gBufA,gBufB;
57
58 /*
59 * On Macs with a genuine VIA chip there is no way to mask an individual slot
60 * interrupt. This limitation also seems to apply to VIA clone logic cores in
61 * Quadra-like ASICs. (RBV and OSS machines don't have this limitation.)
62 *
63 * We used to fake it by configuring the relevant VIA pin as an output
64 * (to mask the interrupt) or input (to unmask). That scheme did not work on
65 * (at least) the Quadra 700. A NuBus card's /NMRQ signal is an open-collector
66 * circuit (see Designing Cards and Drivers for Macintosh II and Macintosh SE,
67 * p. 10-11 etc) but VIA outputs are not (see datasheet).
68 *
69 * Driving these outputs high must cause the VIA to source current and the
70 * card to sink current when it asserts /NMRQ. Current will flow but the pin
71 * voltage is uncertain and so the /NMRQ condition may still cause a transition
72 * at the VIA2 CA1 input (which explains the lost interrupts). A side effect
73 * is that a disabled slot IRQ can never be tested as pending or not.
74 *
75 * Driving these outputs low doesn't work either. All the slot /NMRQ lines are
76 * (active low) OR'd together to generate the CA1 (aka "SLOTS") interrupt (see
77 * The Guide To Macintosh Family Hardware, 2nd edition p. 167). If we drive a
78 * disabled /NMRQ line low, the falling edge immediately triggers a CA1
79 * interrupt and all slot interrupts after that will generate no transition
80 * and therefore no interrupt, even after being re-enabled.
81 *
82 * So we make the VIA port A I/O lines inputs and use nubus_disabled to keep
83 * track of their states. When any slot IRQ becomes disabled we mask the CA1
84 * umbrella interrupt. Only when all slot IRQs become enabled do we unmask
85 * the CA1 interrupt. It must remain enabled even when cards have no interrupt
86 * handler registered. Drivers must therefore disable a slot interrupt at the
87 * device before they call free_irq (like shared and autovector interrupts).
88 *
89 * There is also a related problem when MacOS is used to boot Linux. A network
90 * card brought up by a MacOS driver may raise an interrupt while Linux boots.
91 * This can be fatal since it can't be handled until the right driver loads
92 * (if such a driver exists at all). Apparently related to this hardware
93 * limitation, "Designing Cards and Drivers", p. 9-8, says that a slot
94 * interrupt with no driver would crash MacOS (the book was written before
95 * the appearance of Macs with RBV or OSS).
96 */
97
98 static u8 nubus_disabled;
99
100 void via_debug_dump(void);
101 static void via_nubus_init(void);
102
103 /*
104 * Initialize the VIAs
105 *
106 * First we figure out where they actually _are_ as well as what type of
107 * VIA we have for VIA2 (it could be a real VIA or an RBV or even an OSS.)
108 * Then we pretty much clear them out and disable all IRQ sources.
109 */
110
111 void __init via_init(void)
112 {
113 via1 = (void *)VIA1_BASE;
114 pr_debug("VIA1 detected at %p\n", via1);
115
116 if (oss_present) {
117 via2 = NULL;
118 rbv_present = 0;
119 } else {
120 switch (macintosh_config->via_type) {
121
122 /* IIci, IIsi, IIvx, IIvi (P6xx), LC series */
123
124 case MAC_VIA_IICI:
125 via2 = (void *)RBV_BASE;
126 pr_debug("VIA2 (RBV) detected at %p\n", via2);
127 rbv_present = 1;
128 if (macintosh_config->ident == MAC_MODEL_LCIII) {
129 rbv_clear = 0x00;
130 } else {
131 /* on most RBVs (& unlike the VIAs), you */
132 /* need to set bit 7 when you write to IFR */
133 /* in order for your clear to occur. */
134 rbv_clear = 0x80;
135 }
136 gIER = rIER;
137 gIFR = rIFR;
138 gBufA = rSIFR;
139 gBufB = rBufB;
140 break;
141
142 /* Quadra and early MacIIs agree on the VIA locations */
143
144 case MAC_VIA_QUADRA:
145 case MAC_VIA_II:
146 via2 = (void *) VIA2_BASE;
147 pr_debug("VIA2 detected at %p\n", via2);
148 rbv_present = 0;
149 rbv_clear = 0x00;
150 gIER = vIER;
151 gIFR = vIFR;
152 gBufA = vBufA;
153 gBufB = vBufB;
154 break;
155
156 default:
157 panic("UNKNOWN VIA TYPE");
158 }
159 }
160
161 #ifdef DEBUG_VIA
162 via_debug_dump();
163 #endif
164
165 /*
166 * Shut down all IRQ sources, reset the timers, and
167 * kill the timer latch on VIA1.
168 */
169
170 via1[vIER] = 0x7F;
171 via1[vIFR] = 0x7F;
172 via1[vT1LL] = 0;
173 via1[vT1LH] = 0;
174 via1[vT1CL] = 0;
175 via1[vT1CH] = 0;
176 via1[vT2CL] = 0;
177 via1[vT2CH] = 0;
178 via1[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
179 via1[vACR] &= ~0x03; /* disable port A & B latches */
180
181 /*
182 * SE/30: disable video IRQ
183 */
184
185 if (macintosh_config->ident == MAC_MODEL_SE30) {
186 via1[vDirB] |= 0x40;
187 via1[vBufB] |= 0x40;
188 }
189
190 switch (macintosh_config->adb_type) {
191 case MAC_ADB_IOP:
192 case MAC_ADB_II:
193 case MAC_ADB_PB1:
194 /*
195 * Set the RTC bits to a known state: all lines to outputs and
196 * RTC disabled (yes that's 0 to enable and 1 to disable).
197 */
198 via1[vDirB] |= VIA1B_vRTCEnb | VIA1B_vRTCClk | VIA1B_vRTCData;
199 via1[vBufB] |= VIA1B_vRTCEnb | VIA1B_vRTCClk;
200 break;
201 }
202
203 /* Everything below this point is VIA2/RBV only... */
204
205 if (oss_present)
206 return;
207
208 if ((macintosh_config->via_type == MAC_VIA_QUADRA) &&
209 (macintosh_config->adb_type != MAC_ADB_PB1) &&
210 (macintosh_config->adb_type != MAC_ADB_PB2) &&
211 (macintosh_config->ident != MAC_MODEL_C660) &&
212 (macintosh_config->ident != MAC_MODEL_Q840)) {
213 via_alt_mapping = 1;
214 via1[vDirB] |= 0x40;
215 via1[vBufB] &= ~0x40;
216 } else {
217 via_alt_mapping = 0;
218 }
219
220 /*
221 * Now initialize VIA2. For RBV we just kill all interrupts;
222 * for a regular VIA we also reset the timers and stuff.
223 */
224
225 via2[gIER] = 0x7F;
226 via2[gIFR] = 0x7F | rbv_clear;
227 if (!rbv_present) {
228 via2[vT1LL] = 0;
229 via2[vT1LH] = 0;
230 via2[vT1CL] = 0;
231 via2[vT1CH] = 0;
232 via2[vT2CL] = 0;
233 via2[vT2CH] = 0;
234 via2[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
235 via2[vACR] &= ~0x03; /* disable port A & B latches */
236 }
237
238 via_nubus_init();
239
240 /* Everything below this point is VIA2 only... */
241
242 if (rbv_present)
243 return;
244
245 /*
246 * Set vPCR for control line interrupts.
247 *
248 * CA1 (SLOTS IRQ), CB1 (ASC IRQ): negative edge trigger.
249 *
250 * Macs with ESP SCSI have a negative edge triggered SCSI interrupt.
251 * Testing reveals that PowerBooks do too. However, the SE/30
252 * schematic diagram shows an active high NCR5380 IRQ line.
253 */
254
255 pr_debug("VIA2 vPCR is 0x%02X\n", via2[vPCR]);
256 if (macintosh_config->via_type == MAC_VIA_II) {
257 /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, pos. edge */
258 via2[vPCR] = 0x66;
259 } else {
260 /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, neg. edge */
261 via2[vPCR] = 0x22;
262 }
263 }
264
265 /*
266 * Debugging dump, used in various places to see what's going on.
267 */
268
269 void via_debug_dump(void)
270 {
271 printk(KERN_DEBUG "VIA1: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
272 (uint) via1[vDirA], (uint) via1[vDirB], (uint) via1[vACR]);
273 printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
274 (uint) via1[vPCR], (uint) via1[vIFR], (uint) via1[vIER]);
275 if (!via2)
276 return;
277 if (rbv_present) {
278 printk(KERN_DEBUG "VIA2: IFR = 0x%02X IER = 0x%02X\n",
279 (uint) via2[rIFR], (uint) via2[rIER]);
280 printk(KERN_DEBUG " SIFR = 0x%02X SIER = 0x%02X\n",
281 (uint) via2[rSIFR], (uint) via2[rSIER]);
282 } else {
283 printk(KERN_DEBUG "VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
284 (uint) via2[vDirA], (uint) via2[vDirB],
285 (uint) via2[vACR]);
286 printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
287 (uint) via2[vPCR],
288 (uint) via2[vIFR], (uint) via2[vIER]);
289 }
290 }
291
292 /*
293 * Flush the L2 cache on Macs that have it by flipping
294 * the system into 24-bit mode for an instant.
295 */
296
297 void via_flush_cache(void)
298 {
299 via2[gBufB] &= ~VIA2B_vMode32;
300 via2[gBufB] |= VIA2B_vMode32;
301 }
302
303 /*
304 * Return the status of the L2 cache on a IIci
305 */
306
307 int via_get_cache_disable(void)
308 {
309 /* Safeguard against being called accidentally */
310 if (!via2) {
311 printk(KERN_ERR "via_get_cache_disable called on a non-VIA machine!\n");
312 return 1;
313 }
314
315 return (int) via2[gBufB] & VIA2B_vCDis;
316 }
317
318 /*
319 * Initialize VIA2 for Nubus access
320 */
321
322 static void __init via_nubus_init(void)
323 {
324 /* unlock nubus transactions */
325
326 if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
327 (macintosh_config->adb_type != MAC_ADB_PB2)) {
328 /* set the line to be an output on non-RBV machines */
329 if (!rbv_present)
330 via2[vDirB] |= 0x02;
331
332 /* this seems to be an ADB bit on PMU machines */
333 /* according to MkLinux. -- jmt */
334 via2[gBufB] |= 0x02;
335 }
336
337 /*
338 * Disable the slot interrupts. On some hardware that's not possible.
339 * On some hardware it's unclear what all of these I/O lines do.
340 */
341
342 switch (macintosh_config->via_type) {
343 case MAC_VIA_II:
344 case MAC_VIA_QUADRA:
345 pr_debug("VIA2 vDirA is 0x%02X\n", via2[vDirA]);
346 break;
347 case MAC_VIA_IICI:
348 /* RBV. Disable all the slot interrupts. SIER works like IER. */
349 via2[rSIER] = 0x7F;
350 break;
351 }
352 }
353
354 void via_nubus_irq_startup(int irq)
355 {
356 int irq_idx = IRQ_IDX(irq);
357
358 switch (macintosh_config->via_type) {
359 case MAC_VIA_II:
360 case MAC_VIA_QUADRA:
361 /* Make the port A line an input. Probably redundant. */
362 if (macintosh_config->via_type == MAC_VIA_II) {
363 /* The top two bits are RAM size outputs. */
364 via2[vDirA] &= 0xC0 | ~(1 << irq_idx);
365 } else {
366 /* Allow NuBus slots 9 through F. */
367 via2[vDirA] &= 0x80 | ~(1 << irq_idx);
368 }
369 /* fall through */
370 case MAC_VIA_IICI:
371 via_irq_enable(irq);
372 break;
373 }
374 }
375
376 void via_nubus_irq_shutdown(int irq)
377 {
378 switch (macintosh_config->via_type) {
379 case MAC_VIA_II:
380 case MAC_VIA_QUADRA:
381 /* Ensure that the umbrella CA1 interrupt remains enabled. */
382 via_irq_enable(irq);
383 break;
384 case MAC_VIA_IICI:
385 via_irq_disable(irq);
386 break;
387 }
388 }
389
390 /*
391 * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
392 * via6522.c :-), disable/pending masks added.
393 */
394
395 #define VIA_TIMER_1_INT BIT(6)
396
397 void via1_irq(struct irq_desc *desc)
398 {
399 int irq_num;
400 unsigned char irq_bit, events;
401
402 events = via1[vIFR] & via1[vIER] & 0x7F;
403 if (!events)
404 return;
405
406 irq_num = IRQ_MAC_TIMER_1;
407 irq_bit = VIA_TIMER_1_INT;
408 if (events & irq_bit) {
409 unsigned long flags;
410
411 local_irq_save(flags);
412 via1[vIFR] = irq_bit;
413 generic_handle_irq(irq_num);
414 local_irq_restore(flags);
415
416 events &= ~irq_bit;
417 if (!events)
418 return;
419 }
420
421 irq_num = VIA1_SOURCE_BASE;
422 irq_bit = 1;
423 do {
424 if (events & irq_bit) {
425 via1[vIFR] = irq_bit;
426 generic_handle_irq(irq_num);
427 }
428 ++irq_num;
429 irq_bit <<= 1;
430 } while (events >= irq_bit);
431 }
432
433 static void via2_irq(struct irq_desc *desc)
434 {
435 int irq_num;
436 unsigned char irq_bit, events;
437
438 events = via2[gIFR] & via2[gIER] & 0x7F;
439 if (!events)
440 return;
441
442 irq_num = VIA2_SOURCE_BASE;
443 irq_bit = 1;
444 do {
445 if (events & irq_bit) {
446 via2[gIFR] = irq_bit | rbv_clear;
447 generic_handle_irq(irq_num);
448 }
449 ++irq_num;
450 irq_bit <<= 1;
451 } while (events >= irq_bit);
452 }
453
454 /*
455 * Dispatch Nubus interrupts. We are called as a secondary dispatch by the
456 * VIA2 dispatcher as a fast interrupt handler.
457 */
458
459 static void via_nubus_irq(struct irq_desc *desc)
460 {
461 int slot_irq;
462 unsigned char slot_bit, events;
463
464 events = ~via2[gBufA] & 0x7F;
465 if (rbv_present)
466 events &= via2[rSIER];
467 else
468 events &= ~via2[vDirA];
469 if (!events)
470 return;
471
472 do {
473 slot_irq = IRQ_NUBUS_F;
474 slot_bit = 0x40;
475 do {
476 if (events & slot_bit) {
477 events &= ~slot_bit;
478 generic_handle_irq(slot_irq);
479 }
480 --slot_irq;
481 slot_bit >>= 1;
482 } while (events);
483
484 /* clear the CA1 interrupt and make certain there's no more. */
485 via2[gIFR] = 0x02 | rbv_clear;
486 events = ~via2[gBufA] & 0x7F;
487 if (rbv_present)
488 events &= via2[rSIER];
489 else
490 events &= ~via2[vDirA];
491 } while (events);
492 }
493
494 /*
495 * Register the interrupt dispatchers for VIA or RBV machines only.
496 */
497
498 void __init via_register_interrupts(void)
499 {
500 if (via_alt_mapping) {
501 /* software interrupt */
502 irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
503 /* via1 interrupt */
504 irq_set_chained_handler(IRQ_AUTO_6, via1_irq);
505 } else {
506 irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
507 }
508 irq_set_chained_handler(IRQ_AUTO_2, via2_irq);
509 irq_set_chained_handler(IRQ_MAC_NUBUS, via_nubus_irq);
510 }
511
512 void via_irq_enable(int irq) {
513 int irq_src = IRQ_SRC(irq);
514 int irq_idx = IRQ_IDX(irq);
515
516 if (irq_src == 1) {
517 via1[vIER] = IER_SET_BIT(irq_idx);
518 } else if (irq_src == 2) {
519 if (irq != IRQ_MAC_NUBUS || nubus_disabled == 0)
520 via2[gIER] = IER_SET_BIT(irq_idx);
521 } else if (irq_src == 7) {
522 switch (macintosh_config->via_type) {
523 case MAC_VIA_II:
524 case MAC_VIA_QUADRA:
525 nubus_disabled &= ~(1 << irq_idx);
526 /* Enable the CA1 interrupt when no slot is disabled. */
527 if (!nubus_disabled)
528 via2[gIER] = IER_SET_BIT(1);
529 break;
530 case MAC_VIA_IICI:
531 /* On RBV, enable the slot interrupt.
532 * SIER works like IER.
533 */
534 via2[rSIER] = IER_SET_BIT(irq_idx);
535 break;
536 }
537 }
538 }
539
540 void via_irq_disable(int irq) {
541 int irq_src = IRQ_SRC(irq);
542 int irq_idx = IRQ_IDX(irq);
543
544 if (irq_src == 1) {
545 via1[vIER] = IER_CLR_BIT(irq_idx);
546 } else if (irq_src == 2) {
547 via2[gIER] = IER_CLR_BIT(irq_idx);
548 } else if (irq_src == 7) {
549 switch (macintosh_config->via_type) {
550 case MAC_VIA_II:
551 case MAC_VIA_QUADRA:
552 nubus_disabled |= 1 << irq_idx;
553 if (nubus_disabled)
554 via2[gIER] = IER_CLR_BIT(1);
555 break;
556 case MAC_VIA_IICI:
557 via2[rSIER] = IER_CLR_BIT(irq_idx);
558 break;
559 }
560 }
561 }
562
563 void via1_set_head(int head)
564 {
565 if (head == 0)
566 via1[vBufA] &= ~VIA1A_vHeadSel;
567 else
568 via1[vBufA] |= VIA1A_vHeadSel;
569 }
570 EXPORT_SYMBOL(via1_set_head);
571
572 int via2_scsi_drq_pending(void)
573 {
574 return via2[gIFR] & (1 << IRQ_IDX(IRQ_MAC_SCSIDRQ));
575 }
576 EXPORT_SYMBOL(via2_scsi_drq_pending);
577
578 /* timer and clock source */
579
580 #define VIA_CLOCK_FREQ 783360 /* VIA "phase 2" clock in Hz */
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
587 static u64 mac_read_clk(struct clocksource *cs);
588
589 static struct clocksource mac_clk = {
590 .name = "via1",
591 .rating = 250,
592 .read = mac_read_clk,
593 .mask = CLOCKSOURCE_MASK(32),
594 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
595 };
596
597 static u32 clk_total, clk_offset;
598
599 static irqreturn_t via_timer_handler(int irq, void *dev_id)
600 {
601 irq_handler_t timer_routine = dev_id;
602
603 clk_total += VIA_TIMER_CYCLES;
604 clk_offset = 0;
605 timer_routine(0, NULL);
606
607 return IRQ_HANDLED;
608 }
609
610 void __init via_init_clock(irq_handler_t timer_routine)
611 {
612 if (request_irq(IRQ_MAC_TIMER_1, via_timer_handler, IRQF_TIMER, "timer",
613 timer_routine)) {
614 pr_err("Couldn't register %s interrupt\n", "timer");
615 return;
616 }
617
618 via1[vT1LL] = VIA_TC_LOW;
619 via1[vT1LH] = VIA_TC_HIGH;
620 via1[vT1CL] = VIA_TC_LOW;
621 via1[vT1CH] = VIA_TC_HIGH;
622 via1[vACR] |= 0x40;
623
624 clocksource_register_hz(&mac_clk, VIA_CLOCK_FREQ);
625 }
626
627 static u64 mac_read_clk(struct clocksource *cs)
628 {
629 unsigned long flags;
630 u8 count_high;
631 u16 count;
632 u32 ticks;
633
634 /*
635 * Timer counter wrap-around is detected with the timer interrupt flag
636 * but reading the counter low byte (vT1CL) would reset the flag.
637 * Also, accessing both counter registers is essentially a data race.
638 * These problems are avoided by ignoring the low byte. Clock accuracy
639 * is 256 times worse (error can reach 0.327 ms) but CPU overhead is
640 * reduced by avoiding slow VIA register accesses.
641 */
642
643 local_irq_save(flags);
644 count_high = via1[vT1CH];
645 if (count_high == 0xFF)
646 count_high = 0;
647 if (count_high > 0 && (via1[vIFR] & VIA_TIMER_1_INT))
648 clk_offset = VIA_TIMER_CYCLES;
649 count = count_high << 8;
650 ticks = VIA_TIMER_CYCLES - count;
651 ticks += clk_offset + clk_total;
652 local_irq_restore(flags);
653
654 return ticks;
655 }