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;
61 #define TICK_SIZE 10000
62 #define MAC_CLOCK_TICK (783300/HZ) /* ticks per HZ */
63 #define MAC_CLOCK_LOW (MAC_CLOCK_TICK&0xFF)
64 #define MAC_CLOCK_HIGH (MAC_CLOCK_TICK>>8)
68 * On Macs with a genuine VIA chip there is no way to mask an individual slot
69 * interrupt. This limitation also seems to apply to VIA clone logic cores in
70 * Quadra-like ASICs. (RBV and OSS machines don't have this limitation.)
72 * We used to fake it by configuring the relevant VIA pin as an output
73 * (to mask the interrupt) or input (to unmask). That scheme did not work on
74 * (at least) the Quadra 700. A NuBus card's /NMRQ signal is an open-collector
75 * circuit (see Designing Cards and Drivers for Macintosh II and Macintosh SE,
76 * p. 10-11 etc) but VIA outputs are not (see datasheet).
78 * Driving these outputs high must cause the VIA to source current and the
79 * card to sink current when it asserts /NMRQ. Current will flow but the pin
80 * voltage is uncertain and so the /NMRQ condition may still cause a transition
81 * at the VIA2 CA1 input (which explains the lost interrupts). A side effect
82 * is that a disabled slot IRQ can never be tested as pending or not.
84 * Driving these outputs low doesn't work either. All the slot /NMRQ lines are
85 * (active low) OR'd together to generate the CA1 (aka "SLOTS") interrupt (see
86 * The Guide To Macintosh Family Hardware, 2nd edition p. 167). If we drive a
87 * disabled /NMRQ line low, the falling edge immediately triggers a CA1
88 * interrupt and all slot interrupts after that will generate no transition
89 * and therefore no interrupt, even after being re-enabled.
91 * So we make the VIA port A I/O lines inputs and use nubus_disabled to keep
92 * track of their states. When any slot IRQ becomes disabled we mask the CA1
93 * umbrella interrupt. Only when all slot IRQs become enabled do we unmask
94 * the CA1 interrupt. It must remain enabled even when cards have no interrupt
95 * handler registered. Drivers must therefore disable a slot interrupt at the
96 * device before they call free_irq (like shared and autovector interrupts).
98 * There is also a related problem when MacOS is used to boot Linux. A network
99 * card brought up by a MacOS driver may raise an interrupt while Linux boots.
100 * This can be fatal since it can't be handled until the right driver loads
101 * (if such a driver exists at all). Apparently related to this hardware
102 * limitation, "Designing Cards and Drivers", p. 9-8, says that a slot
103 * interrupt with no driver would crash MacOS (the book was written before
104 * the appearance of Macs with RBV or OSS).
107 static u8 nubus_disabled;
109 void via_debug_dump(void);
110 static void via_nubus_init(void);
113 * Initialize the VIAs
115 * First we figure out where they actually _are_ as well as what type of
116 * VIA we have for VIA2 (it could be a real VIA or an RBV or even an OSS.)
117 * Then we pretty much clear them out and disable all IRQ sources.
120 void __init via_init(void)
122 via1 = (void *)VIA1_BASE;
123 pr_debug("VIA1 detected at %p\n", via1);
129 switch (macintosh_config->via_type) {
131 /* IIci, IIsi, IIvx, IIvi (P6xx), LC series */
134 via2 = (void *)RBV_BASE;
135 pr_debug("VIA2 (RBV) detected at %p\n", via2);
137 if (macintosh_config->ident == MAC_MODEL_LCIII) {
140 /* on most RBVs (& unlike the VIAs), you */
141 /* need to set bit 7 when you write to IFR */
142 /* in order for your clear to occur. */
151 /* Quadra and early MacIIs agree on the VIA locations */
155 via2 = (void *) VIA2_BASE;
156 pr_debug("VIA2 detected at %p\n", via2);
166 panic("UNKNOWN VIA TYPE");
175 * Shut down all IRQ sources, reset the timers, and
176 * kill the timer latch on VIA1.
187 via1[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
188 via1[vACR] &= ~0x03; /* disable port A & B latches */
191 * SE/30: disable video IRQ
194 if (macintosh_config->ident == MAC_MODEL_SE30) {
199 switch (macintosh_config->adb_type) {
204 * Set the RTC bits to a known state: all lines to outputs and
205 * 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;
212 /* Everything below this point is VIA2/RBV only... */
217 if ((macintosh_config->via_type == MAC_VIA_QUADRA) &&
218 (macintosh_config->adb_type != MAC_ADB_PB1) &&
219 (macintosh_config->adb_type != MAC_ADB_PB2) &&
220 (macintosh_config->ident != MAC_MODEL_C660) &&
221 (macintosh_config->ident != MAC_MODEL_Q840)) {
224 via1[vBufB] &= ~0x40;
230 * Now initialize VIA2. For RBV we just kill all interrupts;
231 * for a regular VIA we also reset the timers and stuff.
235 via2[gIFR] = 0x7F | rbv_clear;
243 via2[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
244 via2[vACR] &= ~0x03; /* disable port A & B latches */
249 /* Everything below this point is VIA2 only... */
255 * Set vPCR for control line interrupts.
257 * CA1 (SLOTS IRQ), CB1 (ASC IRQ): negative edge trigger.
259 * Macs with ESP SCSI have a negative edge triggered SCSI interrupt.
260 * Testing reveals that PowerBooks do too. However, the SE/30
261 * schematic diagram shows an active high NCR5380 IRQ line.
264 pr_debug("VIA2 vPCR is 0x%02X\n", via2[vPCR]);
265 if (macintosh_config->via_type == MAC_VIA_II) {
266 /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, pos. edge */
269 /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, neg. edge */
275 * Start the 100 Hz clock
278 void __init via_init_clock(irq_handler_t func)
281 via1[vT1LL] = MAC_CLOCK_LOW;
282 via1[vT1LH] = MAC_CLOCK_HIGH;
283 via1[vT1CL] = MAC_CLOCK_LOW;
284 via1[vT1CH] = MAC_CLOCK_HIGH;
286 if (request_irq(IRQ_MAC_TIMER_1, func, 0, "timer", func))
287 pr_err("Couldn't register %s interrupt\n", "timer");
291 * Debugging dump, used in various places to see what's going on.
294 void via_debug_dump(void)
296 printk(KERN_DEBUG "VIA1: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
297 (uint) via1[vDirA], (uint) via1[vDirB], (uint) via1[vACR]);
298 printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
299 (uint) via1[vPCR], (uint) via1[vIFR], (uint) via1[vIER]);
303 printk(KERN_DEBUG "VIA2: IFR = 0x%02X IER = 0x%02X\n",
304 (uint) via2[rIFR], (uint) via2[rIER]);
305 printk(KERN_DEBUG " SIFR = 0x%02X SIER = 0x%02X\n",
306 (uint) via2[rSIFR], (uint) via2[rSIER]);
308 printk(KERN_DEBUG "VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
309 (uint) via2[vDirA], (uint) via2[vDirB],
311 printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
313 (uint) via2[vIFR], (uint) via2[vIER]);
318 * This is always executed with interrupts disabled.
320 * TBI: get time offset between scheduling timer ticks
323 u32 mac_gettimeoffset(void)
325 unsigned long ticks, offset = 0;
327 /* read VIA1 timer 2 current value */
328 ticks = via1[vT1CL] | (via1[vT1CH] << 8);
329 /* The probability of underflow is less than 2% */
330 if (ticks > MAC_CLOCK_TICK - MAC_CLOCK_TICK / 50)
331 /* Check for pending timer interrupt in VIA1 IFR */
332 if (via1[vIFR] & 0x40) offset = TICK_SIZE;
334 ticks = MAC_CLOCK_TICK - ticks;
335 ticks = ticks * 10000L / MAC_CLOCK_TICK;
337 return (ticks + offset) * 1000;
341 * Flush the L2 cache on Macs that have it by flipping
342 * the system into 24-bit mode for an instant.
345 void via_flush_cache(void)
347 via2[gBufB] &= ~VIA2B_vMode32;
348 via2[gBufB] |= VIA2B_vMode32;
352 * Return the status of the L2 cache on a IIci
355 int via_get_cache_disable(void)
357 /* Safeguard against being called accidentally */
359 printk(KERN_ERR "via_get_cache_disable called on a non-VIA machine!\n");
363 return (int) via2[gBufB] & VIA2B_vCDis;
367 * Initialize VIA2 for Nubus access
370 static void __init via_nubus_init(void)
372 /* unlock nubus transactions */
374 if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
375 (macintosh_config->adb_type != MAC_ADB_PB2)) {
376 /* set the line to be an output on non-RBV machines */
380 /* this seems to be an ADB bit on PMU machines */
381 /* according to MkLinux. -- jmt */
386 * Disable the slot interrupts. On some hardware that's not possible.
387 * On some hardware it's unclear what all of these I/O lines do.
390 switch (macintosh_config->via_type) {
393 pr_debug("VIA2 vDirA is 0x%02X\n", via2[vDirA]);
396 /* RBV. Disable all the slot interrupts. SIER works like IER. */
402 void via_nubus_irq_startup(int irq)
404 int irq_idx = IRQ_IDX(irq);
406 switch (macintosh_config->via_type) {
409 /* Make the port A line an input. Probably redundant. */
410 if (macintosh_config->via_type == MAC_VIA_II) {
411 /* The top two bits are RAM size outputs. */
412 via2[vDirA] &= 0xC0 | ~(1 << irq_idx);
414 /* Allow NuBus slots 9 through F. */
415 via2[vDirA] &= 0x80 | ~(1 << irq_idx);
424 void via_nubus_irq_shutdown(int irq)
426 switch (macintosh_config->via_type) {
429 /* Ensure that the umbrella CA1 interrupt remains enabled. */
433 via_irq_disable(irq);
439 * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
440 * via6522.c :-), disable/pending masks added.
443 void via1_irq(struct irq_desc *desc)
446 unsigned char irq_bit, events;
448 events = via1[vIFR] & via1[vIER] & 0x7F;
452 irq_num = VIA1_SOURCE_BASE;
455 if (events & irq_bit) {
456 via1[vIFR] = irq_bit;
457 generic_handle_irq(irq_num);
461 } while (events >= irq_bit);
464 static void via2_irq(struct irq_desc *desc)
467 unsigned char irq_bit, events;
469 events = via2[gIFR] & via2[gIER] & 0x7F;
473 irq_num = VIA2_SOURCE_BASE;
476 if (events & irq_bit) {
477 via2[gIFR] = irq_bit | rbv_clear;
478 generic_handle_irq(irq_num);
482 } while (events >= irq_bit);
486 * Dispatch Nubus interrupts. We are called as a secondary dispatch by the
487 * VIA2 dispatcher as a fast interrupt handler.
490 static void via_nubus_irq(struct irq_desc *desc)
493 unsigned char slot_bit, events;
495 events = ~via2[gBufA] & 0x7F;
497 events &= via2[rSIER];
499 events &= ~via2[vDirA];
504 slot_irq = IRQ_NUBUS_F;
507 if (events & slot_bit) {
509 generic_handle_irq(slot_irq);
515 /* clear the CA1 interrupt and make certain there's no more. */
516 via2[gIFR] = 0x02 | rbv_clear;
517 events = ~via2[gBufA] & 0x7F;
519 events &= via2[rSIER];
521 events &= ~via2[vDirA];
526 * Register the interrupt dispatchers for VIA or RBV machines only.
529 void __init via_register_interrupts(void)
531 if (via_alt_mapping) {
532 /* software interrupt */
533 irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
535 irq_set_chained_handler(IRQ_AUTO_6, via1_irq);
537 irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
539 irq_set_chained_handler(IRQ_AUTO_2, via2_irq);
540 irq_set_chained_handler(IRQ_MAC_NUBUS, via_nubus_irq);
543 void via_irq_enable(int irq) {
544 int irq_src = IRQ_SRC(irq);
545 int irq_idx = IRQ_IDX(irq);
548 via1[vIER] = IER_SET_BIT(irq_idx);
549 } else if (irq_src == 2) {
550 if (irq != IRQ_MAC_NUBUS || nubus_disabled == 0)
551 via2[gIER] = IER_SET_BIT(irq_idx);
552 } else if (irq_src == 7) {
553 switch (macintosh_config->via_type) {
556 nubus_disabled &= ~(1 << irq_idx);
557 /* Enable the CA1 interrupt when no slot is disabled. */
559 via2[gIER] = IER_SET_BIT(1);
562 /* On RBV, enable the slot interrupt.
563 * SIER works like IER.
565 via2[rSIER] = IER_SET_BIT(irq_idx);
571 void via_irq_disable(int irq) {
572 int irq_src = IRQ_SRC(irq);
573 int irq_idx = IRQ_IDX(irq);
576 via1[vIER] = IER_CLR_BIT(irq_idx);
577 } else if (irq_src == 2) {
578 via2[gIER] = IER_CLR_BIT(irq_idx);
579 } else if (irq_src == 7) {
580 switch (macintosh_config->via_type) {
583 nubus_disabled |= 1 << irq_idx;
585 via2[gIER] = IER_CLR_BIT(1);
588 via2[rSIER] = IER_CLR_BIT(irq_idx);
594 void via1_set_head(int head)
597 via1[vBufA] &= ~VIA1A_vHeadSel;
599 via1[vBufA] |= VIA1A_vHeadSel;
601 EXPORT_SYMBOL(via1_set_head);
603 int via2_scsi_drq_pending(void)
605 return via2[gIFR] & (1 << IRQ_IDX(IRQ_MAC_SCSIDRQ));
607 EXPORT_SYMBOL(via2_scsi_drq_pending);