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 #include "mac.h"
42
43 volatile __u8 *via1, *via2;
44 int rbv_present;
45 int via_alt_mapping;
46 EXPORT_SYMBOL(via_alt_mapping);
47 static __u8 rbv_clear;
48
49 /*
50 * Globals for accessing the VIA chip registers without having to
51 * check if we're hitting a real VIA or an RBV. Normally you could
52 * just hit the combined register (ie, vIER|rIER) but that seems to
53 * break on AV Macs...probably because they actually decode more than
54 * eight address bits. Why can't Apple engineers at least be
55 * _consistently_ lazy? - 1999-05-21 (jmt)
56 */
57
58 static int gIER,gIFR,gBufA,gBufB;
59
60 /*
61 * On Macs with a genuine VIA chip there is no way to mask an individual slot
62 * interrupt. This limitation also seems to apply to VIA clone logic cores in
63 * Quadra-like ASICs. (RBV and OSS machines don't have this limitation.)
64 *
65 * We used to fake it by configuring the relevant VIA pin as an output
66 * (to mask the interrupt) or input (to unmask). That scheme did not work on
67 * (at least) the Quadra 700. A NuBus card's /NMRQ signal is an open-collector
68 * circuit (see Designing Cards and Drivers for Macintosh II and Macintosh SE,
69 * p. 10-11 etc) but VIA outputs are not (see datasheet).
70 *
71 * Driving these outputs high must cause the VIA to source current and the
72 * card to sink current when it asserts /NMRQ. Current will flow but the pin
73 * voltage is uncertain and so the /NMRQ condition may still cause a transition
74 * at the VIA2 CA1 input (which explains the lost interrupts). A side effect
75 * is that a disabled slot IRQ can never be tested as pending or not.
76 *
77 * Driving these outputs low doesn't work either. All the slot /NMRQ lines are
78 * (active low) OR'd together to generate the CA1 (aka "SLOTS") interrupt (see
79 * The Guide To Macintosh Family Hardware, 2nd edition p. 167). If we drive a
80 * disabled /NMRQ line low, the falling edge immediately triggers a CA1
81 * interrupt and all slot interrupts after that will generate no transition
82 * and therefore no interrupt, even after being re-enabled.
83 *
84 * So we make the VIA port A I/O lines inputs and use nubus_disabled to keep
85 * track of their states. When any slot IRQ becomes disabled we mask the CA1
86 * umbrella interrupt. Only when all slot IRQs become enabled do we unmask
87 * the CA1 interrupt. It must remain enabled even when cards have no interrupt
88 * handler registered. Drivers must therefore disable a slot interrupt at the
89 * device before they call free_irq (like shared and autovector interrupts).
90 *
91 * There is also a related problem when MacOS is used to boot Linux. A network
92 * card brought up by a MacOS driver may raise an interrupt while Linux boots.
93 * This can be fatal since it can't be handled until the right driver loads
94 * (if such a driver exists at all). Apparently related to this hardware
95 * limitation, "Designing Cards and Drivers", p. 9-8, says that a slot
96 * interrupt with no driver would crash MacOS (the book was written before
97 * the appearance of Macs with RBV or OSS).
98 */
99
100 static u8 nubus_disabled;
101
102 void via_debug_dump(void);
103 static void via_nubus_init(void);
104
105 /*
106 * Initialize the VIAs
107 *
108 * First we figure out where they actually _are_ as well as what type of
109 * VIA we have for VIA2 (it could be a real VIA or an RBV or even an OSS.)
110 * Then we pretty much clear them out and disable all IRQ sources.
111 */
112
113 void __init via_init(void)
114 {
115 via1 = (void *)VIA1_BASE;
116 pr_debug("VIA1 detected at %p\n", via1);
117
118 if (oss_present) {
119 via2 = NULL;
120 rbv_present = 0;
121 } else {
122 switch (macintosh_config->via_type) {
123
124 /* IIci, IIsi, IIvx, IIvi (P6xx), LC series */
125
126 case MAC_VIA_IICI:
127 via2 = (void *)RBV_BASE;
128 pr_debug("VIA2 (RBV) detected at %p\n", via2);
129 rbv_present = 1;
130 if (macintosh_config->ident == MAC_MODEL_LCIII) {
131 rbv_clear = 0x00;
132 } else {
133 /* on most RBVs (& unlike the VIAs), you */
134 /* need to set bit 7 when you write to IFR */
135 /* in order for your clear to occur. */
136 rbv_clear = 0x80;
137 }
138 gIER = rIER;
139 gIFR = rIFR;
140 gBufA = rSIFR;
141 gBufB = rBufB;
142 break;
143
144 /* Quadra and early MacIIs agree on the VIA locations */
145
146 case MAC_VIA_QUADRA:
147 case MAC_VIA_II:
148 via2 = (void *) VIA2_BASE;
149 pr_debug("VIA2 detected at %p\n", via2);
150 rbv_present = 0;
151 rbv_clear = 0x00;
152 gIER = vIER;
153 gIFR = vIFR;
154 gBufA = vBufA;
155 gBufB = vBufB;
156 break;
157
158 default:
159 panic("UNKNOWN VIA TYPE");
160 }
161 }
162
163 #ifdef DEBUG_VIA
164 via_debug_dump();
165 #endif
166
167 /*
168 * Shut down all IRQ sources, reset the timers, and
169 * kill the timer latch on VIA1.
170 */
171
172 via1[vIER] = 0x7F;
173 via1[vIFR] = 0x7F;
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[vT1CL] = 0;
229 via2[vT1CH] = 0;
230 via2[vT2CL] = 0;
231 via2[vT2CH] = 0;
232 via2[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
233 via2[vACR] &= ~0x03; /* disable port A & B latches */
234 }
235
236 via_nubus_init();
237
238 /* Everything below this point is VIA2 only... */
239
240 if (rbv_present)
241 return;
242
243 /*
244 * Set vPCR for control line interrupts.
245 *
246 * CA1 (SLOTS IRQ), CB1 (ASC IRQ): negative edge trigger.
247 *
248 * Macs with ESP SCSI have a negative edge triggered SCSI interrupt.
249 * Testing reveals that PowerBooks do too. However, the SE/30
250 * schematic diagram shows an active high NCR5380 IRQ line.
251 */
252
253 pr_debug("VIA2 vPCR is 0x%02X\n", via2[vPCR]);
254 if (macintosh_config->via_type == MAC_VIA_II) {
255 /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, pos. edge */
256 via2[vPCR] = 0x66;
257 } else {
258 /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, neg. edge */
259 via2[vPCR] = 0x22;
260 }
261 }
262
263 /*
264 * Debugging dump, used in various places to see what's going on.
265 */
266
267 void via_debug_dump(void)
268 {
269 printk(KERN_DEBUG "VIA1: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
270 (uint) via1[vDirA], (uint) via1[vDirB], (uint) via1[vACR]);
271 printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
272 (uint) via1[vPCR], (uint) via1[vIFR], (uint) via1[vIER]);
273 if (!via2)
274 return;
275 if (rbv_present) {
276 printk(KERN_DEBUG "VIA2: IFR = 0x%02X IER = 0x%02X\n",
277 (uint) via2[rIFR], (uint) via2[rIER]);
278 printk(KERN_DEBUG " SIFR = 0x%02X SIER = 0x%02X\n",
279 (uint) via2[rSIFR], (uint) via2[rSIER]);
280 } else {
281 printk(KERN_DEBUG "VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
282 (uint) via2[vDirA], (uint) via2[vDirB],
283 (uint) via2[vACR]);
284 printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
285 (uint) via2[vPCR],
286 (uint) via2[vIFR], (uint) via2[vIER]);
287 }
288 }
289
290 /*
291 * Flush the L2 cache on Macs that have it by flipping
292 * the system into 24-bit mode for an instant.
293 */
294
295 void via_l2_flush(int writeback)
296 {
297 unsigned long flags;
298
299 local_irq_save(flags);
300 via2[gBufB] &= ~VIA2B_vMode32;
301 via2[gBufB] |= VIA2B_vMode32;
302 local_irq_restore(flags);
303 }
304
305 /*
306 * Initialize VIA2 for Nubus access
307 */
308
309 static void __init via_nubus_init(void)
310 {
311 /* unlock nubus transactions */
312
313 if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
314 (macintosh_config->adb_type != MAC_ADB_PB2)) {
315 /* set the line to be an output on non-RBV machines */
316 if (!rbv_present)
317 via2[vDirB] |= 0x02;
318
319 /* this seems to be an ADB bit on PMU machines */
320 /* according to MkLinux. -- jmt */
321 via2[gBufB] |= 0x02;
322 }
323
324 /*
325 * Disable the slot interrupts. On some hardware that's not possible.
326 * On some hardware it's unclear what all of these I/O lines do.
327 */
328
329 switch (macintosh_config->via_type) {
330 case MAC_VIA_II:
331 case MAC_VIA_QUADRA:
332 pr_debug("VIA2 vDirA is 0x%02X\n", via2[vDirA]);
333 break;
334 case MAC_VIA_IICI:
335 /* RBV. Disable all the slot interrupts. SIER works like IER. */
336 via2[rSIER] = 0x7F;
337 break;
338 }
339 }
340
341 void via_nubus_irq_startup(int irq)
342 {
343 int irq_idx = IRQ_IDX(irq);
344
345 switch (macintosh_config->via_type) {
346 case MAC_VIA_II:
347 case MAC_VIA_QUADRA:
348 /* Make the port A line an input. Probably redundant. */
349 if (macintosh_config->via_type == MAC_VIA_II) {
350 /* The top two bits are RAM size outputs. */
351 via2[vDirA] &= 0xC0 | ~(1 << irq_idx);
352 } else {
353 /* Allow NuBus slots 9 through F. */
354 via2[vDirA] &= 0x80 | ~(1 << irq_idx);
355 }
356 fallthrough;
357 case MAC_VIA_IICI:
358 via_irq_enable(irq);
359 break;
360 }
361 }
362
363 void via_nubus_irq_shutdown(int irq)
364 {
365 switch (macintosh_config->via_type) {
366 case MAC_VIA_II:
367 case MAC_VIA_QUADRA:
368 /* Ensure that the umbrella CA1 interrupt remains enabled. */
369 via_irq_enable(irq);
370 break;
371 case MAC_VIA_IICI:
372 via_irq_disable(irq);
373 break;
374 }
375 }
376
377 /*
378 * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
379 * via6522.c :-), disable/pending masks added.
380 */
381
382 #define VIA_TIMER_1_INT BIT(6)
383
384 void via1_irq(struct irq_desc *desc)
385 {
386 int irq_num;
387 unsigned char irq_bit, events;
388
389 events = via1[vIFR] & via1[vIER] & 0x7F;
390 if (!events)
391 return;
392
393 irq_num = IRQ_MAC_TIMER_1;
394 irq_bit = VIA_TIMER_1_INT;
395 if (events & irq_bit) {
396 unsigned long flags;
397
398 local_irq_save(flags);
399 via1[vIFR] = irq_bit;
400 generic_handle_irq(irq_num);
401 local_irq_restore(flags);
402
403 events &= ~irq_bit;
404 if (!events)
405 return;
406 }
407
408 irq_num = VIA1_SOURCE_BASE;
409 irq_bit = 1;
410 do {
411 if (events & irq_bit) {
412 via1[vIFR] = irq_bit;
413 generic_handle_irq(irq_num);
414 }
415 ++irq_num;
416 irq_bit <<= 1;
417 } while (events >= irq_bit);
418 }
419
420 static void via2_irq(struct irq_desc *desc)
421 {
422 int irq_num;
423 unsigned char irq_bit, events;
424
425 events = via2[gIFR] & via2[gIER] & 0x7F;
426 if (!events)
427 return;
428
429 irq_num = VIA2_SOURCE_BASE;
430 irq_bit = 1;
431 do {
432 if (events & irq_bit) {
433 via2[gIFR] = irq_bit | rbv_clear;
434 generic_handle_irq(irq_num);
435 }
436 ++irq_num;
437 irq_bit <<= 1;
438 } while (events >= irq_bit);
439 }
440
441 /*
442 * Dispatch Nubus interrupts. We are called as a secondary dispatch by the
443 * VIA2 dispatcher as a fast interrupt handler.
444 */
445
446 static void via_nubus_irq(struct irq_desc *desc)
447 {
448 int slot_irq;
449 unsigned char slot_bit, events;
450
451 events = ~via2[gBufA] & 0x7F;
452 if (rbv_present)
453 events &= via2[rSIER];
454 else
455 events &= ~via2[vDirA];
456 if (!events)
457 return;
458
459 do {
460 slot_irq = IRQ_NUBUS_F;
461 slot_bit = 0x40;
462 do {
463 if (events & slot_bit) {
464 events &= ~slot_bit;
465 generic_handle_irq(slot_irq);
466 }
467 --slot_irq;
468 slot_bit >>= 1;
469 } while (events);
470
471 /* clear the CA1 interrupt and make certain there's no more. */
472 via2[gIFR] = 0x02 | rbv_clear;
473 events = ~via2[gBufA] & 0x7F;
474 if (rbv_present)
475 events &= via2[rSIER];
476 else
477 events &= ~via2[vDirA];
478 } while (events);
479 }
480
481 /*
482 * Register the interrupt dispatchers for VIA or RBV machines only.
483 */
484
485 void __init via_register_interrupts(void)
486 {
487 if (via_alt_mapping) {
488 /* software interrupt */
489 irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
490 /* via1 interrupt */
491 irq_set_chained_handler(IRQ_AUTO_6, via1_irq);
492 } else {
493 irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
494 }
495 irq_set_chained_handler(IRQ_AUTO_2, via2_irq);
496 irq_set_chained_handler(IRQ_MAC_NUBUS, via_nubus_irq);
497 }
498
499 void via_irq_enable(int irq) {
500 int irq_src = IRQ_SRC(irq);
501 int irq_idx = IRQ_IDX(irq);
502
503 if (irq_src == 1) {
504 via1[vIER] = IER_SET_BIT(irq_idx);
505 } else if (irq_src == 2) {
506 if (irq != IRQ_MAC_NUBUS || nubus_disabled == 0)
507 via2[gIER] = IER_SET_BIT(irq_idx);
508 } else if (irq_src == 7) {
509 switch (macintosh_config->via_type) {
510 case MAC_VIA_II:
511 case MAC_VIA_QUADRA:
512 nubus_disabled &= ~(1 << irq_idx);
513 /* Enable the CA1 interrupt when no slot is disabled. */
514 if (!nubus_disabled)
515 via2[gIER] = IER_SET_BIT(1);
516 break;
517 case MAC_VIA_IICI:
518 /* On RBV, enable the slot interrupt.
519 * SIER works like IER.
520 */
521 via2[rSIER] = IER_SET_BIT(irq_idx);
522 break;
523 }
524 }
525 }
526
527 void via_irq_disable(int irq) {
528 int irq_src = IRQ_SRC(irq);
529 int irq_idx = IRQ_IDX(irq);
530
531 if (irq_src == 1) {
532 via1[vIER] = IER_CLR_BIT(irq_idx);
533 } else if (irq_src == 2) {
534 via2[gIER] = IER_CLR_BIT(irq_idx);
535 } else if (irq_src == 7) {
536 switch (macintosh_config->via_type) {
537 case MAC_VIA_II:
538 case MAC_VIA_QUADRA:
539 nubus_disabled |= 1 << irq_idx;
540 if (nubus_disabled)
541 via2[gIER] = IER_CLR_BIT(1);
542 break;
543 case MAC_VIA_IICI:
544 via2[rSIER] = IER_CLR_BIT(irq_idx);
545 break;
546 }
547 }
548 }
549
550 void via1_set_head(int head)
551 {
552 if (head == 0)
553 via1[vBufA] &= ~VIA1A_vHeadSel;
554 else
555 via1[vBufA] |= VIA1A_vHeadSel;
556 }
557 EXPORT_SYMBOL(via1_set_head);
558
559 int via2_scsi_drq_pending(void)
560 {
561 return via2[gIFR] & (1 << IRQ_IDX(IRQ_MAC_SCSIDRQ));
562 }
563 EXPORT_SYMBOL(via2_scsi_drq_pending);
564
565 /* timer and clock source */
566
567 #define VIA_CLOCK_FREQ 783360 /* VIA "phase 2" clock in Hz */
568 #define VIA_TIMER_CYCLES (VIA_CLOCK_FREQ / HZ) /* clock cycles per jiffy */
569
570 #define VIA_TC (VIA_TIMER_CYCLES - 2) /* including 0 and -1 */
571 #define VIA_TC_LOW (VIA_TC & 0xFF)
572 #define VIA_TC_HIGH (VIA_TC >> 8)
573
574 static u64 mac_read_clk(struct clocksource *cs);
575
576 static struct clocksource mac_clk = {
577 .name = "via1",
578 .rating = 250,
579 .read = mac_read_clk,
580 .mask = CLOCKSOURCE_MASK(32),
581 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
582 };
583
584 static u32 clk_total, clk_offset;
585
586 static irqreturn_t via_timer_handler(int irq, void *dev_id)
587 {
588 clk_total += VIA_TIMER_CYCLES;
589 clk_offset = 0;
590 legacy_timer_tick(1);
591
592 return IRQ_HANDLED;
593 }
594
595 void __init via_init_clock(void)
596 {
597 if (request_irq(IRQ_MAC_TIMER_1, via_timer_handler, IRQF_TIMER, "timer",
598 NULL)) {
599 pr_err("Couldn't register %s interrupt\n", "timer");
600 return;
601 }
602
603 via1[vT1CL] = VIA_TC_LOW;
604 via1[vT1CH] = VIA_TC_HIGH;
605 via1[vACR] |= 0x40;
606
607 clocksource_register_hz(&mac_clk, VIA_CLOCK_FREQ);
608 }
609
610 static u64 mac_read_clk(struct clocksource *cs)
611 {
612 unsigned long flags;
613 u8 count_high;
614 u16 count;
615 u32 ticks;
616
617 /*
618 * Timer counter wrap-around is detected with the timer interrupt flag
619 * but reading the counter low byte (vT1CL) would reset the flag.
620 * Also, accessing both counter registers is essentially a data race.
621 * These problems are avoided by ignoring the low byte. Clock accuracy
622 * is 256 times worse (error can reach 0.327 ms) but CPU overhead is
623 * reduced by avoiding slow VIA register accesses.
624 */
625
626 local_irq_save(flags);
627 count_high = via1[vT1CH];
628 if (count_high == 0xFF)
629 count_high = 0;
630 if (count_high > 0 && (via1[vIFR] & VIA_TIMER_1_INT))
631 clk_offset = VIA_TIMER_CYCLES;
632 count = count_high << 8;
633 ticks = VIA_TIMER_CYCLES - count;
634 ticks += clk_offset + clk_total;
635 local_irq_restore(flags);
636
637 return ticks;
638 }
639
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