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
via_init(void)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[vT1CL] = 0;
173 via1[vT1CH] = 0;
174 via1[vT2CL] = 0;
175 via1[vT2CH] = 0;
176 via1[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
177 via1[vACR] &= ~0x03; /* disable port A & B latches */
178
179 /*
180 * SE/30: disable video IRQ
181 */
182
183 if (macintosh_config->ident == MAC_MODEL_SE30) {
184 via1[vDirB] |= 0x40;
185 via1[vBufB] |= 0x40;
186 }
187
188 switch (macintosh_config->adb_type) {
189 case MAC_ADB_IOP:
190 case MAC_ADB_II:
191 case MAC_ADB_PB1:
192 /*
193 * Set the RTC bits to a known state: all lines to outputs and
194 * RTC disabled (yes that's 0 to enable and 1 to disable).
195 */
196 via1[vDirB] |= VIA1B_vRTCEnb | VIA1B_vRTCClk | VIA1B_vRTCData;
197 via1[vBufB] |= VIA1B_vRTCEnb | VIA1B_vRTCClk;
198 break;
199 }
200
201 /* Everything below this point is VIA2/RBV only... */
202
203 if (oss_present)
204 return;
205
206 if ((macintosh_config->via_type == MAC_VIA_QUADRA) &&
207 (macintosh_config->adb_type != MAC_ADB_PB1) &&
208 (macintosh_config->adb_type != MAC_ADB_PB2) &&
209 (macintosh_config->ident != MAC_MODEL_C660) &&
210 (macintosh_config->ident != MAC_MODEL_Q840)) {
211 via_alt_mapping = 1;
212 via1[vDirB] |= 0x40;
213 via1[vBufB] &= ~0x40;
214 } else {
215 via_alt_mapping = 0;
216 }
217
218 /*
219 * Now initialize VIA2. For RBV we just kill all interrupts;
220 * for a regular VIA we also reset the timers and stuff.
221 */
222
223 via2[gIER] = 0x7F;
224 via2[gIFR] = 0x7F | rbv_clear;
225 if (!rbv_present) {
226 via2[vT1CL] = 0;
227 via2[vT1CH] = 0;
228 via2[vT2CL] = 0;
229 via2[vT2CH] = 0;
230 via2[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
231 via2[vACR] &= ~0x03; /* disable port A & B latches */
232 }
233
234 via_nubus_init();
235
236 /* Everything below this point is VIA2 only... */
237
238 if (rbv_present)
239 return;
240
241 /*
242 * Set vPCR for control line interrupts.
243 *
244 * CA1 (SLOTS IRQ), CB1 (ASC IRQ): negative edge trigger.
245 *
246 * Macs with ESP SCSI have a negative edge triggered SCSI interrupt.
247 * Testing reveals that PowerBooks do too. However, the SE/30
248 * schematic diagram shows an active high NCR5380 IRQ line.
249 */
250
251 pr_debug("VIA2 vPCR is 0x%02X\n", via2[vPCR]);
252 if (macintosh_config->via_type == MAC_VIA_II) {
253 /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, pos. edge */
254 via2[vPCR] = 0x66;
255 } else {
256 /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, neg. edge */
257 via2[vPCR] = 0x22;
258 }
259 }
260
261 /*
262 * Debugging dump, used in various places to see what's going on.
263 */
264
via_debug_dump(void)265 void via_debug_dump(void)
266 {
267 printk(KERN_DEBUG "VIA1: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
268 (uint) via1[vDirA], (uint) via1[vDirB], (uint) via1[vACR]);
269 printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
270 (uint) via1[vPCR], (uint) via1[vIFR], (uint) via1[vIER]);
271 if (!via2)
272 return;
273 if (rbv_present) {
274 printk(KERN_DEBUG "VIA2: IFR = 0x%02X IER = 0x%02X\n",
275 (uint) via2[rIFR], (uint) via2[rIER]);
276 printk(KERN_DEBUG " SIFR = 0x%02X SIER = 0x%02X\n",
277 (uint) via2[rSIFR], (uint) via2[rSIER]);
278 } else {
279 printk(KERN_DEBUG "VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
280 (uint) via2[vDirA], (uint) via2[vDirB],
281 (uint) via2[vACR]);
282 printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
283 (uint) via2[vPCR],
284 (uint) via2[vIFR], (uint) via2[vIER]);
285 }
286 }
287
288 /*
289 * Flush the L2 cache on Macs that have it by flipping
290 * the system into 24-bit mode for an instant.
291 */
292
via_l2_flush(int writeback)293 void via_l2_flush(int writeback)
294 {
295 unsigned long flags;
296
297 local_irq_save(flags);
298 via2[gBufB] &= ~VIA2B_vMode32;
299 via2[gBufB] |= VIA2B_vMode32;
300 local_irq_restore(flags);
301 }
302
303 /*
304 * Initialize VIA2 for Nubus access
305 */
306
via_nubus_init(void)307 static void __init via_nubus_init(void)
308 {
309 /* unlock nubus transactions */
310
311 if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
312 (macintosh_config->adb_type != MAC_ADB_PB2)) {
313 /* set the line to be an output on non-RBV machines */
314 if (!rbv_present)
315 via2[vDirB] |= 0x02;
316
317 /* this seems to be an ADB bit on PMU machines */
318 /* according to MkLinux. -- jmt */
319 via2[gBufB] |= 0x02;
320 }
321
322 /*
323 * Disable the slot interrupts. On some hardware that's not possible.
324 * On some hardware it's unclear what all of these I/O lines do.
325 */
326
327 switch (macintosh_config->via_type) {
328 case MAC_VIA_II:
329 case MAC_VIA_QUADRA:
330 pr_debug("VIA2 vDirA is 0x%02X\n", via2[vDirA]);
331 break;
332 case MAC_VIA_IICI:
333 /* RBV. Disable all the slot interrupts. SIER works like IER. */
334 via2[rSIER] = 0x7F;
335 break;
336 }
337 }
338
via_nubus_irq_startup(int irq)339 void via_nubus_irq_startup(int irq)
340 {
341 int irq_idx = IRQ_IDX(irq);
342
343 switch (macintosh_config->via_type) {
344 case MAC_VIA_II:
345 case MAC_VIA_QUADRA:
346 /* Make the port A line an input. Probably redundant. */
347 if (macintosh_config->via_type == MAC_VIA_II) {
348 /* The top two bits are RAM size outputs. */
349 via2[vDirA] &= 0xC0 | ~(1 << irq_idx);
350 } else {
351 /* Allow NuBus slots 9 through F. */
352 via2[vDirA] &= 0x80 | ~(1 << irq_idx);
353 }
354 fallthrough;
355 case MAC_VIA_IICI:
356 via_irq_enable(irq);
357 break;
358 }
359 }
360
via_nubus_irq_shutdown(int irq)361 void via_nubus_irq_shutdown(int irq)
362 {
363 switch (macintosh_config->via_type) {
364 case MAC_VIA_II:
365 case MAC_VIA_QUADRA:
366 /* Ensure that the umbrella CA1 interrupt remains enabled. */
367 via_irq_enable(irq);
368 break;
369 case MAC_VIA_IICI:
370 via_irq_disable(irq);
371 break;
372 }
373 }
374
375 /*
376 * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
377 * via6522.c :-), disable/pending masks added.
378 */
379
380 #define VIA_TIMER_1_INT BIT(6)
381
via1_irq(struct irq_desc * desc)382 void via1_irq(struct irq_desc *desc)
383 {
384 int irq_num;
385 unsigned char irq_bit, events;
386
387 events = via1[vIFR] & via1[vIER] & 0x7F;
388 if (!events)
389 return;
390
391 irq_num = IRQ_MAC_TIMER_1;
392 irq_bit = VIA_TIMER_1_INT;
393 if (events & irq_bit) {
394 unsigned long flags;
395
396 local_irq_save(flags);
397 via1[vIFR] = irq_bit;
398 generic_handle_irq(irq_num);
399 local_irq_restore(flags);
400
401 events &= ~irq_bit;
402 if (!events)
403 return;
404 }
405
406 irq_num = VIA1_SOURCE_BASE;
407 irq_bit = 1;
408 do {
409 if (events & irq_bit) {
410 via1[vIFR] = irq_bit;
411 generic_handle_irq(irq_num);
412 }
413 ++irq_num;
414 irq_bit <<= 1;
415 } while (events >= irq_bit);
416 }
417
via2_irq(struct irq_desc * desc)418 static void via2_irq(struct irq_desc *desc)
419 {
420 int irq_num;
421 unsigned char irq_bit, events;
422
423 events = via2[gIFR] & via2[gIER] & 0x7F;
424 if (!events)
425 return;
426
427 irq_num = VIA2_SOURCE_BASE;
428 irq_bit = 1;
429 do {
430 if (events & irq_bit) {
431 via2[gIFR] = irq_bit | rbv_clear;
432 generic_handle_irq(irq_num);
433 }
434 ++irq_num;
435 irq_bit <<= 1;
436 } while (events >= irq_bit);
437 }
438
439 /*
440 * Dispatch Nubus interrupts. We are called as a secondary dispatch by the
441 * VIA2 dispatcher as a fast interrupt handler.
442 */
443
via_nubus_irq(struct irq_desc * desc)444 static void via_nubus_irq(struct irq_desc *desc)
445 {
446 int slot_irq;
447 unsigned char slot_bit, events;
448
449 events = ~via2[gBufA] & 0x7F;
450 if (rbv_present)
451 events &= via2[rSIER];
452 else
453 events &= ~via2[vDirA];
454 if (!events)
455 return;
456
457 do {
458 slot_irq = IRQ_NUBUS_F;
459 slot_bit = 0x40;
460 do {
461 if (events & slot_bit) {
462 events &= ~slot_bit;
463 generic_handle_irq(slot_irq);
464 }
465 --slot_irq;
466 slot_bit >>= 1;
467 } while (events);
468
469 /* clear the CA1 interrupt and make certain there's no more. */
470 via2[gIFR] = 0x02 | rbv_clear;
471 events = ~via2[gBufA] & 0x7F;
472 if (rbv_present)
473 events &= via2[rSIER];
474 else
475 events &= ~via2[vDirA];
476 } while (events);
477 }
478
479 /*
480 * Register the interrupt dispatchers for VIA or RBV machines only.
481 */
482
via_register_interrupts(void)483 void __init via_register_interrupts(void)
484 {
485 if (via_alt_mapping) {
486 /* software interrupt */
487 irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
488 /* via1 interrupt */
489 irq_set_chained_handler(IRQ_AUTO_6, via1_irq);
490 } else {
491 irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
492 }
493 irq_set_chained_handler(IRQ_AUTO_2, via2_irq);
494 irq_set_chained_handler(IRQ_MAC_NUBUS, via_nubus_irq);
495 }
496
via_irq_enable(int irq)497 void via_irq_enable(int irq) {
498 int irq_src = IRQ_SRC(irq);
499 int irq_idx = IRQ_IDX(irq);
500
501 if (irq_src == 1) {
502 via1[vIER] = IER_SET_BIT(irq_idx);
503 } else if (irq_src == 2) {
504 if (irq != IRQ_MAC_NUBUS || nubus_disabled == 0)
505 via2[gIER] = IER_SET_BIT(irq_idx);
506 } else if (irq_src == 7) {
507 switch (macintosh_config->via_type) {
508 case MAC_VIA_II:
509 case MAC_VIA_QUADRA:
510 nubus_disabled &= ~(1 << irq_idx);
511 /* Enable the CA1 interrupt when no slot is disabled. */
512 if (!nubus_disabled)
513 via2[gIER] = IER_SET_BIT(1);
514 break;
515 case MAC_VIA_IICI:
516 /* On RBV, enable the slot interrupt.
517 * SIER works like IER.
518 */
519 via2[rSIER] = IER_SET_BIT(irq_idx);
520 break;
521 }
522 }
523 }
524
via_irq_disable(int irq)525 void via_irq_disable(int irq) {
526 int irq_src = IRQ_SRC(irq);
527 int irq_idx = IRQ_IDX(irq);
528
529 if (irq_src == 1) {
530 via1[vIER] = IER_CLR_BIT(irq_idx);
531 } else if (irq_src == 2) {
532 via2[gIER] = IER_CLR_BIT(irq_idx);
533 } else if (irq_src == 7) {
534 switch (macintosh_config->via_type) {
535 case MAC_VIA_II:
536 case MAC_VIA_QUADRA:
537 nubus_disabled |= 1 << irq_idx;
538 if (nubus_disabled)
539 via2[gIER] = IER_CLR_BIT(1);
540 break;
541 case MAC_VIA_IICI:
542 via2[rSIER] = IER_CLR_BIT(irq_idx);
543 break;
544 }
545 }
546 }
547
via1_set_head(int head)548 void via1_set_head(int head)
549 {
550 if (head == 0)
551 via1[vBufA] &= ~VIA1A_vHeadSel;
552 else
553 via1[vBufA] |= VIA1A_vHeadSel;
554 }
555 EXPORT_SYMBOL(via1_set_head);
556
via2_scsi_drq_pending(void)557 int via2_scsi_drq_pending(void)
558 {
559 return via2[gIFR] & (1 << IRQ_IDX(IRQ_MAC_SCSIDRQ));
560 }
561 EXPORT_SYMBOL(via2_scsi_drq_pending);
562
563 /* timer and clock source */
564
565 #define VIA_CLOCK_FREQ 783360 /* VIA "phase 2" clock in Hz */
566 #define VIA_TIMER_CYCLES (VIA_CLOCK_FREQ / HZ) /* clock cycles per jiffy */
567
568 #define VIA_TC (VIA_TIMER_CYCLES - 2) /* including 0 and -1 */
569 #define VIA_TC_LOW (VIA_TC & 0xFF)
570 #define VIA_TC_HIGH (VIA_TC >> 8)
571
572 static u64 mac_read_clk(struct clocksource *cs);
573
574 static struct clocksource mac_clk = {
575 .name = "via1",
576 .rating = 250,
577 .read = mac_read_clk,
578 .mask = CLOCKSOURCE_MASK(32),
579 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
580 };
581
582 static u32 clk_total, clk_offset;
583
via_timer_handler(int irq,void * dev_id)584 static irqreturn_t via_timer_handler(int irq, void *dev_id)
585 {
586 clk_total += VIA_TIMER_CYCLES;
587 clk_offset = 0;
588 legacy_timer_tick(1);
589
590 return IRQ_HANDLED;
591 }
592
via_init_clock(void)593 void __init via_init_clock(void)
594 {
595 if (request_irq(IRQ_MAC_TIMER_1, via_timer_handler, IRQF_TIMER, "timer",
596 NULL)) {
597 pr_err("Couldn't register %s interrupt\n", "timer");
598 return;
599 }
600
601 via1[vT1CL] = VIA_TC_LOW;
602 via1[vT1CH] = VIA_TC_HIGH;
603 via1[vACR] |= 0x40;
604
605 clocksource_register_hz(&mac_clk, VIA_CLOCK_FREQ);
606 }
607
mac_read_clk(struct clocksource * cs)608 static u64 mac_read_clk(struct clocksource *cs)
609 {
610 unsigned long flags;
611 u8 count_high;
612 u16 count;
613 u32 ticks;
614
615 /*
616 * Timer counter wrap-around is detected with the timer interrupt flag
617 * but reading the counter low byte (vT1CL) would reset the flag.
618 * Also, accessing both counter registers is essentially a data race.
619 * These problems are avoided by ignoring the low byte. Clock accuracy
620 * is 256 times worse (error can reach 0.327 ms) but CPU overhead is
621 * reduced by avoiding slow VIA register accesses.
622 */
623
624 local_irq_save(flags);
625 count_high = via1[vT1CH];
626 if (count_high == 0xFF)
627 count_high = 0;
628 if (count_high > 0 && (via1[vIFR] & VIA_TIMER_1_INT))
629 clk_offset = VIA_TIMER_CYCLES;
630 count = count_high << 8;
631 ticks = VIA_TIMER_CYCLES - count;
632 ticks += clk_offset + clk_total;
633 local_irq_restore(flags);
634
635 return ticks;
636 }
637