2 * 6522 Versatile Interface Adapter (VIA)
4 * There are two of these on the Mac II. Some IRQs are vectored
5 * via them as are assorted bits and bobs - eg RTC, ADB.
7 * CSA: Motorola seems to have removed documentation on the 6522 from
9 * http://nerini.drf.com/vectrex/other/text/chips/6522/
10 * http://www.zymurgy.net/classic/vic20/vicdet1.htm
12 * http://193.23.168.87/mikro_laborversuche/via_iobaustein/via6522_1.html
13 * for info. A full-text web search on 6522 AND VIA will probably also
14 * net some usefulness. <cananian@alumni.princeton.edu> 20apr1999
16 * Additional data is here (the SY6522 was used in the Mac II etc):
17 * http://www.6502.org/documents/datasheets/synertek/synertek_sy6522.pdf
18 * http://www.6502.org/documents/datasheets/synertek/synertek_sy6522_programming_reference.pdf
20 * PRAM/RTC access algorithms are from the NetBSD RTC toolkit version 1.08b
21 * by Erik Vogan and adapted to Linux by Joshua M. Thompson (funaho@jurai.org)
25 #include <linux/types.h>
26 #include <linux/kernel.h>
28 #include <linux/delay.h>
29 #include <linux/init.h>
30 #include <linux/module.h>
31 #include <linux/irq.h>
33 #include <asm/macintosh.h>
34 #include <asm/macints.h>
35 #include <asm/mac_via.h>
36 #include <asm/mac_psc.h>
37 #include <asm/mac_oss.h>
39 volatile __u8 *via1, *via2;
42 EXPORT_SYMBOL(via_alt_mapping);
43 static __u8 rbv_clear;
46 * Globals for accessing the VIA chip registers without having to
47 * check if we're hitting a real VIA or an RBV. Normally you could
48 * just hit the combined register (ie, vIER|rIER) but that seems to
49 * break on AV Macs...probably because they actually decode more than
50 * eight address bits. Why can't Apple engineers at least be
51 * _consistently_ lazy? - 1999-05-21 (jmt)
54 static int gIER,gIFR,gBufA,gBufB;
57 * On Macs with a genuine VIA chip there is no way to mask an individual slot
58 * interrupt. This limitation also seems to apply to VIA clone logic cores in
59 * Quadra-like ASICs. (RBV and OSS machines don't have this limitation.)
61 * We used to fake it by configuring the relevant VIA pin as an output
62 * (to mask the interrupt) or input (to unmask). That scheme did not work on
63 * (at least) the Quadra 700. A NuBus card's /NMRQ signal is an open-collector
64 * circuit (see Designing Cards and Drivers for Macintosh II and Macintosh SE,
65 * p. 10-11 etc) but VIA outputs are not (see datasheet).
67 * Driving these outputs high must cause the VIA to source current and the
68 * card to sink current when it asserts /NMRQ. Current will flow but the pin
69 * voltage is uncertain and so the /NMRQ condition may still cause a transition
70 * at the VIA2 CA1 input (which explains the lost interrupts). A side effect
71 * is that a disabled slot IRQ can never be tested as pending or not.
73 * Driving these outputs low doesn't work either. All the slot /NMRQ lines are
74 * (active low) OR'd together to generate the CA1 (aka "SLOTS") interrupt (see
75 * The Guide To Macintosh Family Hardware, 2nd edition p. 167). If we drive a
76 * disabled /NMRQ line low, the falling edge immediately triggers a CA1
77 * interrupt and all slot interrupts after that will generate no transition
78 * and therefore no interrupt, even after being re-enabled.
80 * So we make the VIA port A I/O lines inputs and use nubus_disabled to keep
81 * track of their states. When any slot IRQ becomes disabled we mask the CA1
82 * umbrella interrupt. Only when all slot IRQs become enabled do we unmask
83 * the CA1 interrupt. It must remain enabled even when cards have no interrupt
84 * handler registered. Drivers must therefore disable a slot interrupt at the
85 * device before they call free_irq (like shared and autovector interrupts).
87 * There is also a related problem when MacOS is used to boot Linux. A network
88 * card brought up by a MacOS driver may raise an interrupt while Linux boots.
89 * This can be fatal since it can't be handled until the right driver loads
90 * (if such a driver exists at all). Apparently related to this hardware
91 * limitation, "Designing Cards and Drivers", p. 9-8, says that a slot
92 * interrupt with no driver would crash MacOS (the book was written before
93 * the appearance of Macs with RBV or OSS).
96 static u8 nubus_disabled;
98 void via_debug_dump(void);
101 * Initialize the VIAs
103 * First we figure out where they actually _are_ as well as what type of
104 * VIA we have for VIA2 (it could be a real VIA or an RBV or even an OSS.)
105 * Then we pretty much clear them out and disable all IRQ sources.
107 * Note: the OSS is actually "detected" here and not in oss_init(). It just
108 * seems more logical to do it here since via_init() needs to know
109 * these things anyways.
112 void __init via_init(void)
114 switch(macintosh_config->via_type) {
116 /* IIci, IIsi, IIvx, IIvi (P6xx), LC series */
119 via1 = (void *) VIA1_BASE;
120 if (macintosh_config->ident == MAC_MODEL_IIFX) {
125 via2 = (void *) RBV_BASE;
129 if (macintosh_config->ident == MAC_MODEL_LCIII) {
132 /* on most RBVs (& unlike the VIAs), you */
133 /* need to set bit 7 when you write to IFR */
134 /* in order for your clear to occur. */
143 /* Quadra and early MacIIs agree on the VIA locations */
147 via1 = (void *) VIA1_BASE;
148 via2 = (void *) VIA2_BASE;
158 panic("UNKNOWN VIA TYPE");
161 printk(KERN_INFO "VIA1 at %p is a 6522 or clone\n", via1);
163 printk(KERN_INFO "VIA2 at %p is ", via2);
166 } else if (oss_present) {
169 printk("a 6522 or clone\n");
177 * Shut down all IRQ sources, reset the timers, and
178 * kill the timer latch on VIA1.
189 via1[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
190 via1[vACR] &= ~0x03; /* disable port A & B latches */
193 * SE/30: disable video IRQ
194 * XXX: testing for SE/30 VBL
197 if (macintosh_config->ident == MAC_MODEL_SE30) {
203 * Set the RTC bits to a known state: all lines to outputs and
204 * RTC disabled (yes that's 0 to enable and 1 to disable).
207 via1[vDirB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk | VIA1B_vRTCData);
208 via1[vBufB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk);
210 /* Everything below this point is VIA2/RBV only... */
215 if ((macintosh_config->via_type == MAC_VIA_QUADRA) &&
216 (macintosh_config->adb_type != MAC_ADB_PB1) &&
217 (macintosh_config->adb_type != MAC_ADB_PB2) &&
218 (macintosh_config->ident != MAC_MODEL_C660) &&
219 (macintosh_config->ident != MAC_MODEL_Q840)) {
222 via1[vBufB] &= ~0x40;
228 * Now initialize VIA2. For RBV we just kill all interrupts;
229 * for a regular VIA we also reset the timers and stuff.
233 via2[gIFR] = 0x7F | rbv_clear;
241 via2[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
242 via2[vACR] &= ~0x03; /* disable port A & B latches */
245 /* Everything below this point is VIA2 only... */
251 * Set vPCR for control line interrupts.
253 * CA1 (SLOTS IRQ), CB1 (ASC IRQ): negative edge trigger.
255 * Macs with ESP SCSI have a negative edge triggered SCSI interrupt.
256 * Testing reveals that PowerBooks do too. However, the SE/30
257 * schematic diagram shows an active high NCR5380 IRQ line.
260 pr_debug("VIA2 vPCR is 0x%02X\n", via2[vPCR]);
261 if (macintosh_config->via_type == MAC_VIA_II) {
262 /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, pos. edge */
265 /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, neg. edge */
271 * Debugging dump, used in various places to see what's going on.
274 void via_debug_dump(void)
276 printk(KERN_DEBUG "VIA1: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
277 (uint) via1[vDirA], (uint) via1[vDirB], (uint) via1[vACR]);
278 printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
279 (uint) via1[vPCR], (uint) via1[vIFR], (uint) via1[vIER]);
281 printk(KERN_DEBUG "VIA2: <OSS>\n");
282 } else if (rbv_present) {
283 printk(KERN_DEBUG "VIA2: IFR = 0x%02X IER = 0x%02X\n",
284 (uint) via2[rIFR], (uint) via2[rIER]);
285 printk(KERN_DEBUG " SIFR = 0x%02X SIER = 0x%02X\n",
286 (uint) via2[rSIFR], (uint) via2[rSIER]);
288 printk(KERN_DEBUG "VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
289 (uint) via2[vDirA], (uint) via2[vDirB],
291 printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
293 (uint) via2[vIFR], (uint) via2[vIER]);
298 * Flush the L2 cache on Macs that have it by flipping
299 * the system into 24-bit mode for an instant.
302 void via_l2_flush(int writeback)
306 local_irq_save(flags);
307 via2[gBufB] &= ~VIA2B_vMode32;
308 via2[gBufB] |= VIA2B_vMode32;
309 local_irq_restore(flags);
313 * Return the status of the L2 cache on a IIci
316 int via_get_cache_disable(void)
318 /* Safeguard against being called accidentally */
320 printk(KERN_ERR "via_get_cache_disable called on a non-VIA machine!\n");
324 return (int) via2[gBufB] & VIA2B_vCDis;
328 * Initialize VIA2 for Nubus access
331 void __init via_nubus_init(void)
333 /* unlock nubus transactions */
335 if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
336 (macintosh_config->adb_type != MAC_ADB_PB2)) {
337 /* set the line to be an output on non-RBV machines */
341 /* this seems to be an ADB bit on PMU machines */
342 /* according to MkLinux. -- jmt */
347 * Disable the slot interrupts. On some hardware that's not possible.
348 * On some hardware it's unclear what all of these I/O lines do.
351 switch (macintosh_config->via_type) {
354 pr_debug("VIA2 vDirA is 0x%02X\n", via2[vDirA]);
357 /* RBV. Disable all the slot interrupts. SIER works like IER. */
363 void via_nubus_irq_startup(int irq)
365 int irq_idx = IRQ_IDX(irq);
367 switch (macintosh_config->via_type) {
370 /* Make the port A line an input. Probably redundant. */
371 if (macintosh_config->via_type == MAC_VIA_II) {
372 /* The top two bits are RAM size outputs. */
373 via2[vDirA] &= 0xC0 | ~(1 << irq_idx);
375 /* Allow NuBus slots 9 through F. */
376 via2[vDirA] &= 0x80 | ~(1 << irq_idx);
385 void via_nubus_irq_shutdown(int irq)
387 switch (macintosh_config->via_type) {
390 /* Ensure that the umbrella CA1 interrupt remains enabled. */
394 via_irq_disable(irq);
400 * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
401 * via6522.c :-), disable/pending masks added.
404 #define VIA_TIMER_1_INT BIT(6)
406 void via1_irq(struct irq_desc *desc)
409 unsigned char irq_bit, events;
411 events = via1[vIFR] & via1[vIER] & 0x7F;
415 irq_num = IRQ_MAC_TIMER_1;
416 irq_bit = VIA_TIMER_1_INT;
417 if (events & irq_bit) {
420 local_irq_save(flags);
421 via1[vIFR] = irq_bit;
422 generic_handle_irq(irq_num);
423 local_irq_restore(flags);
430 irq_num = VIA1_SOURCE_BASE;
433 if (events & irq_bit) {
434 via1[vIFR] = irq_bit;
435 generic_handle_irq(irq_num);
439 } while (events >= irq_bit);
442 static void via2_irq(struct irq_desc *desc)
445 unsigned char irq_bit, events;
447 events = via2[gIFR] & via2[gIER] & 0x7F;
451 irq_num = VIA2_SOURCE_BASE;
454 if (events & irq_bit) {
455 via2[gIFR] = irq_bit | rbv_clear;
456 generic_handle_irq(irq_num);
460 } while (events >= irq_bit);
464 * Dispatch Nubus interrupts. We are called as a secondary dispatch by the
465 * VIA2 dispatcher as a fast interrupt handler.
468 static void via_nubus_irq(struct irq_desc *desc)
471 unsigned char slot_bit, events;
473 events = ~via2[gBufA] & 0x7F;
475 events &= via2[rSIER];
477 events &= ~via2[vDirA];
482 slot_irq = IRQ_NUBUS_F;
485 if (events & slot_bit) {
487 generic_handle_irq(slot_irq);
493 /* clear the CA1 interrupt and make certain there's no more. */
494 via2[gIFR] = 0x02 | rbv_clear;
495 events = ~via2[gBufA] & 0x7F;
497 events &= via2[rSIER];
499 events &= ~via2[vDirA];
504 * Register the interrupt dispatchers for VIA or RBV machines only.
507 void __init via_register_interrupts(void)
509 if (via_alt_mapping) {
510 /* software interrupt */
511 irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
513 irq_set_chained_handler(IRQ_AUTO_6, via1_irq);
515 irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
517 irq_set_chained_handler(IRQ_AUTO_2, via2_irq);
518 irq_set_chained_handler(IRQ_MAC_NUBUS, via_nubus_irq);
521 void via_irq_enable(int irq) {
522 int irq_src = IRQ_SRC(irq);
523 int irq_idx = IRQ_IDX(irq);
526 printk(KERN_DEBUG "via_irq_enable(%d)\n", irq);
530 via1[vIER] = IER_SET_BIT(irq_idx);
531 } else if (irq_src == 2) {
532 if (irq != IRQ_MAC_NUBUS || nubus_disabled == 0)
533 via2[gIER] = IER_SET_BIT(irq_idx);
534 } else if (irq_src == 7) {
535 switch (macintosh_config->via_type) {
538 nubus_disabled &= ~(1 << irq_idx);
539 /* Enable the CA1 interrupt when no slot is disabled. */
541 via2[gIER] = IER_SET_BIT(1);
544 /* On RBV, enable the slot interrupt.
545 * SIER works like IER.
547 via2[rSIER] = IER_SET_BIT(irq_idx);
553 void via_irq_disable(int irq) {
554 int irq_src = IRQ_SRC(irq);
555 int irq_idx = IRQ_IDX(irq);
558 printk(KERN_DEBUG "via_irq_disable(%d)\n", irq);
562 via1[vIER] = IER_CLR_BIT(irq_idx);
563 } else if (irq_src == 2) {
564 via2[gIER] = IER_CLR_BIT(irq_idx);
565 } else if (irq_src == 7) {
566 switch (macintosh_config->via_type) {
569 nubus_disabled |= 1 << irq_idx;
571 via2[gIER] = IER_CLR_BIT(1);
574 via2[rSIER] = IER_CLR_BIT(irq_idx);
580 void via1_set_head(int head)
583 via1[vBufA] &= ~VIA1A_vHeadSel;
585 via1[vBufA] |= VIA1A_vHeadSel;
587 EXPORT_SYMBOL(via1_set_head);
589 int via2_scsi_drq_pending(void)
591 return via2[gIFR] & (1 << IRQ_IDX(IRQ_MAC_SCSIDRQ));
593 EXPORT_SYMBOL(via2_scsi_drq_pending);
595 /* timer and clock source */
597 #define VIA_CLOCK_FREQ 783360 /* VIA "phase 2" clock in Hz */
598 #define VIA_TIMER_INTERVAL (1000000 / HZ) /* microseconds per jiffy */
599 #define VIA_TIMER_CYCLES (VIA_CLOCK_FREQ / HZ) /* clock cycles per jiffy */
601 #define VIA_TC (VIA_TIMER_CYCLES - 2) /* including 0 and -1 */
602 #define VIA_TC_LOW (VIA_TC & 0xFF)
603 #define VIA_TC_HIGH (VIA_TC >> 8)
605 void __init via_init_clock(irq_handler_t timer_routine)
607 if (request_irq(IRQ_MAC_TIMER_1, timer_routine, 0, "timer", NULL)) {
608 pr_err("Couldn't register %s interrupt\n", "timer");
612 via1[vT1LL] = VIA_TC_LOW;
613 via1[vT1LH] = VIA_TC_HIGH;
614 via1[vT1CL] = VIA_TC_LOW;
615 via1[vT1CH] = VIA_TC_HIGH;
619 u32 mac_gettimeoffset(void)
623 u16 count, offset = 0;
626 * Timer counter wrap-around is detected with the timer interrupt flag
627 * but reading the counter low byte (vT1CL) would reset the flag.
628 * Also, accessing both counter registers is essentially a data race.
629 * These problems are avoided by ignoring the low byte. Clock accuracy
630 * is 256 times worse (error can reach 0.327 ms) but CPU overhead is
631 * reduced by avoiding slow VIA register accesses.
634 local_irq_save(flags);
635 count_high = via1[vT1CH];
636 if (count_high == 0xFF)
638 if (count_high > 0 && (via1[vIFR] & VIA_TIMER_1_INT))
639 offset = VIA_TIMER_CYCLES;
640 local_irq_restore(flags);
642 count = count_high << 8;
643 count = VIA_TIMER_CYCLES - count + offset;
645 return ((count * VIA_TIMER_INTERVAL) / VIA_TIMER_CYCLES) * 1000;