1 // SPDX-License-Identifier: GPL-2.0
3 * 6522 Versatile Interface Adapter (VIA)
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.
8 * CSA: Motorola seems to have removed documentation on the 6522 from
10 * http://nerini.drf.com/vectrex/other/text/chips/6522/
11 * http://www.zymurgy.net/classic/vic20/vicdet1.htm
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
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
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)
26 #include <linux/types.h>
27 #include <linux/kernel.h>
29 #include <linux/delay.h>
30 #include <linux/init.h>
31 #include <linux/module.h>
32 #include <linux/irq.h>
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>
40 volatile __u8 *via1, *via2;
43 EXPORT_SYMBOL(via_alt_mapping);
44 static __u8 rbv_clear;
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)
55 static int gIER,gIFR,gBufA,gBufB;
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.)
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).
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.
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.
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).
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).
97 static u8 nubus_disabled;
99 void via_debug_dump(void);
100 static void via_nubus_init(void);
103 * Initialize the VIAs
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.
110 void __init via_init(void)
112 via1 = (void *)VIA1_BASE;
113 pr_debug("VIA1 detected at %p\n", via1);
119 switch (macintosh_config->via_type) {
121 /* IIci, IIsi, IIvx, IIvi (P6xx), LC series */
124 via2 = (void *)RBV_BASE;
125 pr_debug("VIA2 (RBV) detected at %p\n", via2);
127 if (macintosh_config->ident == MAC_MODEL_LCIII) {
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. */
141 /* Quadra and early MacIIs agree on the VIA locations */
145 via2 = (void *) VIA2_BASE;
146 pr_debug("VIA2 detected at %p\n", via2);
156 panic("UNKNOWN VIA TYPE");
165 * Shut down all IRQ sources, reset the timers, and
166 * kill the timer latch on VIA1.
177 via1[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
178 via1[vACR] &= ~0x03; /* disable port A & B latches */
181 * SE/30: disable video IRQ
182 * XXX: testing for SE/30 VBL
185 if (macintosh_config->ident == MAC_MODEL_SE30) {
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).
195 via1[vDirB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk | VIA1B_vRTCData);
196 via1[vBufB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk);
198 /* Everything below this point is VIA2/RBV only... */
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)) {
210 via1[vBufB] &= ~0x40;
216 * Now initialize VIA2. For RBV we just kill all interrupts;
217 * for a regular VIA we also reset the timers and stuff.
221 via2[gIFR] = 0x7F | rbv_clear;
229 via2[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
230 via2[vACR] &= ~0x03; /* disable port A & B latches */
235 /* Everything below this point is VIA2 only... */
241 * Set vPCR for control line interrupts.
243 * CA1 (SLOTS IRQ), CB1 (ASC IRQ): negative edge trigger.
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.
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 */
255 /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, neg. edge */
261 * Debugging dump, used in various places to see what's going on.
264 void via_debug_dump(void)
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]);
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]);
278 printk(KERN_DEBUG "VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
279 (uint) via2[vDirA], (uint) via2[vDirB],
281 printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
283 (uint) via2[vIFR], (uint) via2[vIER]);
288 * Flush the L2 cache on Macs that have it by flipping
289 * the system into 24-bit mode for an instant.
292 void via_l2_flush(int writeback)
296 local_irq_save(flags);
297 via2[gBufB] &= ~VIA2B_vMode32;
298 via2[gBufB] |= VIA2B_vMode32;
299 local_irq_restore(flags);
303 * Return the status of the L2 cache on a IIci
306 int via_get_cache_disable(void)
308 /* Safeguard against being called accidentally */
310 printk(KERN_ERR "via_get_cache_disable called on a non-VIA machine!\n");
314 return (int) via2[gBufB] & VIA2B_vCDis;
318 * Initialize VIA2 for Nubus access
321 static void __init via_nubus_init(void)
323 /* unlock nubus transactions */
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 */
331 /* this seems to be an ADB bit on PMU machines */
332 /* according to MkLinux. -- jmt */
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.
341 switch (macintosh_config->via_type) {
344 pr_debug("VIA2 vDirA is 0x%02X\n", via2[vDirA]);
347 /* RBV. Disable all the slot interrupts. SIER works like IER. */
353 void via_nubus_irq_startup(int irq)
355 int irq_idx = IRQ_IDX(irq);
357 switch (macintosh_config->via_type) {
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);
365 /* Allow NuBus slots 9 through F. */
366 via2[vDirA] &= 0x80 | ~(1 << irq_idx);
375 void via_nubus_irq_shutdown(int irq)
377 switch (macintosh_config->via_type) {
380 /* Ensure that the umbrella CA1 interrupt remains enabled. */
384 via_irq_disable(irq);
390 * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
391 * via6522.c :-), disable/pending masks added.
394 #define VIA_TIMER_1_INT BIT(6)
396 void via1_irq(struct irq_desc *desc)
399 unsigned char irq_bit, events;
401 events = via1[vIFR] & via1[vIER] & 0x7F;
405 irq_num = IRQ_MAC_TIMER_1;
406 irq_bit = VIA_TIMER_1_INT;
407 if (events & irq_bit) {
410 local_irq_save(flags);
411 via1[vIFR] = irq_bit;
412 generic_handle_irq(irq_num);
413 local_irq_restore(flags);
420 irq_num = VIA1_SOURCE_BASE;
423 if (events & irq_bit) {
424 via1[vIFR] = irq_bit;
425 generic_handle_irq(irq_num);
429 } while (events >= irq_bit);
432 static void via2_irq(struct irq_desc *desc)
435 unsigned char irq_bit, events;
437 events = via2[gIFR] & via2[gIER] & 0x7F;
441 irq_num = VIA2_SOURCE_BASE;
444 if (events & irq_bit) {
445 via2[gIFR] = irq_bit | rbv_clear;
446 generic_handle_irq(irq_num);
450 } while (events >= irq_bit);
454 * Dispatch Nubus interrupts. We are called as a secondary dispatch by the
455 * VIA2 dispatcher as a fast interrupt handler.
458 static void via_nubus_irq(struct irq_desc *desc)
461 unsigned char slot_bit, events;
463 events = ~via2[gBufA] & 0x7F;
465 events &= via2[rSIER];
467 events &= ~via2[vDirA];
472 slot_irq = IRQ_NUBUS_F;
475 if (events & slot_bit) {
477 generic_handle_irq(slot_irq);
483 /* clear the CA1 interrupt and make certain there's no more. */
484 via2[gIFR] = 0x02 | rbv_clear;
485 events = ~via2[gBufA] & 0x7F;
487 events &= via2[rSIER];
489 events &= ~via2[vDirA];
494 * Register the interrupt dispatchers for VIA or RBV machines only.
497 void __init via_register_interrupts(void)
499 if (via_alt_mapping) {
500 /* software interrupt */
501 irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
503 irq_set_chained_handler(IRQ_AUTO_6, via1_irq);
505 irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
507 irq_set_chained_handler(IRQ_AUTO_2, via2_irq);
508 irq_set_chained_handler(IRQ_MAC_NUBUS, via_nubus_irq);
511 void via_irq_enable(int irq) {
512 int irq_src = IRQ_SRC(irq);
513 int irq_idx = IRQ_IDX(irq);
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) {
524 nubus_disabled &= ~(1 << irq_idx);
525 /* Enable the CA1 interrupt when no slot is disabled. */
527 via2[gIER] = IER_SET_BIT(1);
530 /* On RBV, enable the slot interrupt.
531 * SIER works like IER.
533 via2[rSIER] = IER_SET_BIT(irq_idx);
539 void via_irq_disable(int irq) {
540 int irq_src = IRQ_SRC(irq);
541 int irq_idx = IRQ_IDX(irq);
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) {
551 nubus_disabled |= 1 << irq_idx;
553 via2[gIER] = IER_CLR_BIT(1);
556 via2[rSIER] = IER_CLR_BIT(irq_idx);
562 void via1_set_head(int head)
565 via1[vBufA] &= ~VIA1A_vHeadSel;
567 via1[vBufA] |= VIA1A_vHeadSel;
569 EXPORT_SYMBOL(via1_set_head);
571 int via2_scsi_drq_pending(void)
573 return via2[gIFR] & (1 << IRQ_IDX(IRQ_MAC_SCSIDRQ));
575 EXPORT_SYMBOL(via2_scsi_drq_pending);
577 /* timer and clock source */
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 */
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)
587 void __init via_init_clock(irq_handler_t timer_routine)
589 if (request_irq(IRQ_MAC_TIMER_1, timer_routine, 0, "timer", NULL)) {
590 pr_err("Couldn't register %s interrupt\n", "timer");
594 via1[vT1LL] = VIA_TC_LOW;
595 via1[vT1LH] = VIA_TC_HIGH;
596 via1[vT1CL] = VIA_TC_LOW;
597 via1[vT1CH] = VIA_TC_HIGH;
601 u32 mac_gettimeoffset(void)
605 u16 count, offset = 0;
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.
616 local_irq_save(flags);
617 count_high = via1[vT1CH];
618 if (count_high == 0xFF)
620 if (count_high > 0 && (via1[vIFR] & VIA_TIMER_1_INT))
621 offset = VIA_TIMER_CYCLES;
622 local_irq_restore(flags);
624 count = count_high << 8;
625 count = VIA_TIMER_CYCLES - count + offset;
627 return ((count * VIA_TIMER_INTERVAL) / VIA_TIMER_CYCLES) * 1000;