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Diffstat (limited to 'arch/m68k/mac/via.c')
| -rw-r--r-- | arch/m68k/mac/via.c | 636 |
1 files changed, 636 insertions, 0 deletions
diff --git a/arch/m68k/mac/via.c b/arch/m68k/mac/via.c new file mode 100644 index 000000000..3d11d6219 --- /dev/null +++ b/arch/m68k/mac/via.c @@ -0,0 +1,636 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * 6522 Versatile Interface Adapter (VIA) + * + * There are two of these on the Mac II. Some IRQs are vectored + * via them as are assorted bits and bobs - eg RTC, ADB. + * + * CSA: Motorola seems to have removed documentation on the 6522 from + * their web site; try + * http://nerini.drf.com/vectrex/other/text/chips/6522/ + * http://www.zymurgy.net/classic/vic20/vicdet1.htm + * and + * http://193.23.168.87/mikro_laborversuche/via_iobaustein/via6522_1.html + * for info. A full-text web search on 6522 AND VIA will probably also + * net some usefulness. <cananian@alumni.princeton.edu> 20apr1999 + * + * Additional data is here (the SY6522 was used in the Mac II etc): + * http://www.6502.org/documents/datasheets/synertek/synertek_sy6522.pdf + * http://www.6502.org/documents/datasheets/synertek/synertek_sy6522_programming_reference.pdf + * + * PRAM/RTC access algorithms are from the NetBSD RTC toolkit version 1.08b + * by Erik Vogan and adapted to Linux by Joshua M. Thompson (funaho@jurai.org) + * + */ + +#include <linux/clocksource.h> +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/delay.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/irq.h> + +#include <asm/macintosh.h> +#include <asm/macints.h> +#include <asm/mac_via.h> +#include <asm/mac_psc.h> +#include <asm/mac_oss.h> + +volatile __u8 *via1, *via2; +int rbv_present; +int via_alt_mapping; +EXPORT_SYMBOL(via_alt_mapping); +static __u8 rbv_clear; + +/* + * Globals for accessing the VIA chip registers without having to + * check if we're hitting a real VIA or an RBV. Normally you could + * just hit the combined register (ie, vIER|rIER) but that seems to + * break on AV Macs...probably because they actually decode more than + * eight address bits. Why can't Apple engineers at least be + * _consistently_ lazy? - 1999-05-21 (jmt) + */ + +static int gIER,gIFR,gBufA,gBufB; + +/* + * On Macs with a genuine VIA chip there is no way to mask an individual slot + * interrupt. This limitation also seems to apply to VIA clone logic cores in + * Quadra-like ASICs. (RBV and OSS machines don't have this limitation.) + * + * We used to fake it by configuring the relevant VIA pin as an output + * (to mask the interrupt) or input (to unmask). That scheme did not work on + * (at least) the Quadra 700. A NuBus card's /NMRQ signal is an open-collector + * circuit (see Designing Cards and Drivers for Macintosh II and Macintosh SE, + * p. 10-11 etc) but VIA outputs are not (see datasheet). + * + * Driving these outputs high must cause the VIA to source current and the + * card to sink current when it asserts /NMRQ. Current will flow but the pin + * voltage is uncertain and so the /NMRQ condition may still cause a transition + * at the VIA2 CA1 input (which explains the lost interrupts). A side effect + * is that a disabled slot IRQ can never be tested as pending or not. + * + * Driving these outputs low doesn't work either. All the slot /NMRQ lines are + * (active low) OR'd together to generate the CA1 (aka "SLOTS") interrupt (see + * The Guide To Macintosh Family Hardware, 2nd edition p. 167). If we drive a + * disabled /NMRQ line low, the falling edge immediately triggers a CA1 + * interrupt and all slot interrupts after that will generate no transition + * and therefore no interrupt, even after being re-enabled. + * + * So we make the VIA port A I/O lines inputs and use nubus_disabled to keep + * track of their states. When any slot IRQ becomes disabled we mask the CA1 + * umbrella interrupt. Only when all slot IRQs become enabled do we unmask + * the CA1 interrupt. It must remain enabled even when cards have no interrupt + * handler registered. Drivers must therefore disable a slot interrupt at the + * device before they call free_irq (like shared and autovector interrupts). + * + * There is also a related problem when MacOS is used to boot Linux. A network + * card brought up by a MacOS driver may raise an interrupt while Linux boots. + * This can be fatal since it can't be handled until the right driver loads + * (if such a driver exists at all). Apparently related to this hardware + * limitation, "Designing Cards and Drivers", p. 9-8, says that a slot + * interrupt with no driver would crash MacOS (the book was written before + * the appearance of Macs with RBV or OSS). + */ + +static u8 nubus_disabled; + +void via_debug_dump(void); +static void via_nubus_init(void); + +/* + * Initialize the VIAs + * + * First we figure out where they actually _are_ as well as what type of + * VIA we have for VIA2 (it could be a real VIA or an RBV or even an OSS.) + * Then we pretty much clear them out and disable all IRQ sources. + */ + +void __init via_init(void) +{ + via1 = (void *)VIA1_BASE; + pr_debug("VIA1 detected at %p\n", via1); + + if (oss_present) { + via2 = NULL; + rbv_present = 0; + } else { + switch (macintosh_config->via_type) { + + /* IIci, IIsi, IIvx, IIvi (P6xx), LC series */ + + case MAC_VIA_IICI: + via2 = (void *)RBV_BASE; + pr_debug("VIA2 (RBV) detected at %p\n", via2); + rbv_present = 1; + if (macintosh_config->ident == MAC_MODEL_LCIII) { + rbv_clear = 0x00; + } else { + /* on most RBVs (& unlike the VIAs), you */ + /* need to set bit 7 when you write to IFR */ + /* in order for your clear to occur. */ + rbv_clear = 0x80; + } + gIER = rIER; + gIFR = rIFR; + gBufA = rSIFR; + gBufB = rBufB; + break; + + /* Quadra and early MacIIs agree on the VIA locations */ + + case MAC_VIA_QUADRA: + case MAC_VIA_II: + via2 = (void *) VIA2_BASE; + pr_debug("VIA2 detected at %p\n", via2); + rbv_present = 0; + rbv_clear = 0x00; + gIER = vIER; + gIFR = vIFR; + gBufA = vBufA; + gBufB = vBufB; + break; + + default: + panic("UNKNOWN VIA TYPE"); + } + } + +#ifdef DEBUG_VIA + via_debug_dump(); +#endif + + /* + * Shut down all IRQ sources, reset the timers, and + * kill the timer latch on VIA1. + */ + + via1[vIER] = 0x7F; + via1[vIFR] = 0x7F; + via1[vT1CL] = 0; + via1[vT1CH] = 0; + via1[vT2CL] = 0; + via1[vT2CH] = 0; + via1[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */ + via1[vACR] &= ~0x03; /* disable port A & B latches */ + + /* + * SE/30: disable video IRQ + */ + + if (macintosh_config->ident == MAC_MODEL_SE30) { + via1[vDirB] |= 0x40; + via1[vBufB] |= 0x40; + } + + switch (macintosh_config->adb_type) { + case MAC_ADB_IOP: + case MAC_ADB_II: + case MAC_ADB_PB1: + /* + * Set the RTC bits to a known state: all lines to outputs and + * RTC disabled (yes that's 0 to enable and 1 to disable). + */ + via1[vDirB] |= VIA1B_vRTCEnb | VIA1B_vRTCClk | VIA1B_vRTCData; + via1[vBufB] |= VIA1B_vRTCEnb | VIA1B_vRTCClk; + break; + } + + /* Everything below this point is VIA2/RBV only... */ + + if (oss_present) + return; + + if ((macintosh_config->via_type == MAC_VIA_QUADRA) && + (macintosh_config->adb_type != MAC_ADB_PB1) && + (macintosh_config->adb_type != MAC_ADB_PB2) && + (macintosh_config->ident != MAC_MODEL_C660) && + (macintosh_config->ident != MAC_MODEL_Q840)) { + via_alt_mapping = 1; + via1[vDirB] |= 0x40; + via1[vBufB] &= ~0x40; + } else { + via_alt_mapping = 0; + } + + /* + * Now initialize VIA2. For RBV we just kill all interrupts; + * for a regular VIA we also reset the timers and stuff. + */ + + via2[gIER] = 0x7F; + via2[gIFR] = 0x7F | rbv_clear; + if (!rbv_present) { + via2[vT1CL] = 0; + via2[vT1CH] = 0; + via2[vT2CL] = 0; + via2[vT2CH] = 0; + via2[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */ + via2[vACR] &= ~0x03; /* disable port A & B latches */ + } + + via_nubus_init(); + + /* Everything below this point is VIA2 only... */ + + if (rbv_present) + return; + + /* + * Set vPCR for control line interrupts. + * + * CA1 (SLOTS IRQ), CB1 (ASC IRQ): negative edge trigger. + * + * Macs with ESP SCSI have a negative edge triggered SCSI interrupt. + * Testing reveals that PowerBooks do too. However, the SE/30 + * schematic diagram shows an active high NCR5380 IRQ line. + */ + + pr_debug("VIA2 vPCR is 0x%02X\n", via2[vPCR]); + if (macintosh_config->via_type == MAC_VIA_II) { + /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, pos. edge */ + via2[vPCR] = 0x66; + } else { + /* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, neg. edge */ + via2[vPCR] = 0x22; + } +} + +/* + * Debugging dump, used in various places to see what's going on. + */ + +void via_debug_dump(void) +{ + printk(KERN_DEBUG "VIA1: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n", + (uint) via1[vDirA], (uint) via1[vDirB], (uint) via1[vACR]); + printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n", + (uint) via1[vPCR], (uint) via1[vIFR], (uint) via1[vIER]); + if (!via2) + return; + if (rbv_present) { + printk(KERN_DEBUG "VIA2: IFR = 0x%02X IER = 0x%02X\n", + (uint) via2[rIFR], (uint) via2[rIER]); + printk(KERN_DEBUG " SIFR = 0x%02X SIER = 0x%02X\n", + (uint) via2[rSIFR], (uint) via2[rSIER]); + } else { + printk(KERN_DEBUG "VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n", + (uint) via2[vDirA], (uint) via2[vDirB], + (uint) via2[vACR]); + printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n", + (uint) via2[vPCR], + (uint) via2[vIFR], (uint) via2[vIER]); + } +} + +/* + * Flush the L2 cache on Macs that have it by flipping + * the system into 24-bit mode for an instant. + */ + +void via_l2_flush(int writeback) +{ + unsigned long flags; + + local_irq_save(flags); + via2[gBufB] &= ~VIA2B_vMode32; + via2[gBufB] |= VIA2B_vMode32; + local_irq_restore(flags); +} + +/* + * Initialize VIA2 for Nubus access + */ + +static void __init via_nubus_init(void) +{ + /* unlock nubus transactions */ + + if ((macintosh_config->adb_type != MAC_ADB_PB1) && + (macintosh_config->adb_type != MAC_ADB_PB2)) { + /* set the line to be an output on non-RBV machines */ + if (!rbv_present) + via2[vDirB] |= 0x02; + + /* this seems to be an ADB bit on PMU machines */ + /* according to MkLinux. -- jmt */ + via2[gBufB] |= 0x02; + } + + /* + * Disable the slot interrupts. On some hardware that's not possible. + * On some hardware it's unclear what all of these I/O lines do. + */ + + switch (macintosh_config->via_type) { + case MAC_VIA_II: + case MAC_VIA_QUADRA: + pr_debug("VIA2 vDirA is 0x%02X\n", via2[vDirA]); + break; + case MAC_VIA_IICI: + /* RBV. Disable all the slot interrupts. SIER works like IER. */ + via2[rSIER] = 0x7F; + break; + } +} + +void via_nubus_irq_startup(int irq) +{ + int irq_idx = IRQ_IDX(irq); + + switch (macintosh_config->via_type) { + case MAC_VIA_II: + case MAC_VIA_QUADRA: + /* Make the port A line an input. Probably redundant. */ + if (macintosh_config->via_type == MAC_VIA_II) { + /* The top two bits are RAM size outputs. */ + via2[vDirA] &= 0xC0 | ~(1 << irq_idx); + } else { + /* Allow NuBus slots 9 through F. */ + via2[vDirA] &= 0x80 | ~(1 << irq_idx); + } + fallthrough; + case MAC_VIA_IICI: + via_irq_enable(irq); + break; + } +} + +void via_nubus_irq_shutdown(int irq) +{ + switch (macintosh_config->via_type) { + case MAC_VIA_II: + case MAC_VIA_QUADRA: + /* Ensure that the umbrella CA1 interrupt remains enabled. */ + via_irq_enable(irq); + break; + case MAC_VIA_IICI: + via_irq_disable(irq); + break; + } +} + +/* + * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's + * via6522.c :-), disable/pending masks added. + */ + +#define VIA_TIMER_1_INT BIT(6) + +void via1_irq(struct irq_desc *desc) +{ + int irq_num; + unsigned char irq_bit, events; + + events = via1[vIFR] & via1[vIER] & 0x7F; + if (!events) + return; + + irq_num = IRQ_MAC_TIMER_1; + irq_bit = VIA_TIMER_1_INT; + if (events & irq_bit) { + unsigned long flags; + + local_irq_save(flags); + via1[vIFR] = irq_bit; + generic_handle_irq(irq_num); + local_irq_restore(flags); + + events &= ~irq_bit; + if (!events) + return; + } + + irq_num = VIA1_SOURCE_BASE; + irq_bit = 1; + do { + if (events & irq_bit) { + via1[vIFR] = irq_bit; + generic_handle_irq(irq_num); + } + ++irq_num; + irq_bit <<= 1; + } while (events >= irq_bit); +} + +static void via2_irq(struct irq_desc *desc) +{ + int irq_num; + unsigned char irq_bit, events; + + events = via2[gIFR] & via2[gIER] & 0x7F; + if (!events) + return; + + irq_num = VIA2_SOURCE_BASE; + irq_bit = 1; + do { + if (events & irq_bit) { + via2[gIFR] = irq_bit | rbv_clear; + generic_handle_irq(irq_num); + } + ++irq_num; + irq_bit <<= 1; + } while (events >= irq_bit); +} + +/* + * Dispatch Nubus interrupts. We are called as a secondary dispatch by the + * VIA2 dispatcher as a fast interrupt handler. + */ + +static void via_nubus_irq(struct irq_desc *desc) +{ + int slot_irq; + unsigned char slot_bit, events; + + events = ~via2[gBufA] & 0x7F; + if (rbv_present) + events &= via2[rSIER]; + else + events &= ~via2[vDirA]; + if (!events) + return; + + do { + slot_irq = IRQ_NUBUS_F; + slot_bit = 0x40; + do { + if (events & slot_bit) { + events &= ~slot_bit; + generic_handle_irq(slot_irq); + } + --slot_irq; + slot_bit >>= 1; + } while (events); + + /* clear the CA1 interrupt and make certain there's no more. */ + via2[gIFR] = 0x02 | rbv_clear; + events = ~via2[gBufA] & 0x7F; + if (rbv_present) + events &= via2[rSIER]; + else + events &= ~via2[vDirA]; + } while (events); +} + +/* + * Register the interrupt dispatchers for VIA or RBV machines only. + */ + +void __init via_register_interrupts(void) +{ + if (via_alt_mapping) { + /* software interrupt */ + irq_set_chained_handler(IRQ_AUTO_1, via1_irq); + /* via1 interrupt */ + irq_set_chained_handler(IRQ_AUTO_6, via1_irq); + } else { + irq_set_chained_handler(IRQ_AUTO_1, via1_irq); + } + irq_set_chained_handler(IRQ_AUTO_2, via2_irq); + irq_set_chained_handler(IRQ_MAC_NUBUS, via_nubus_irq); +} + +void via_irq_enable(int irq) { + int irq_src = IRQ_SRC(irq); + int irq_idx = IRQ_IDX(irq); + + if (irq_src == 1) { + via1[vIER] = IER_SET_BIT(irq_idx); + } else if (irq_src == 2) { + if (irq != IRQ_MAC_NUBUS || nubus_disabled == 0) + via2[gIER] = IER_SET_BIT(irq_idx); + } else if (irq_src == 7) { + switch (macintosh_config->via_type) { + case MAC_VIA_II: + case MAC_VIA_QUADRA: + nubus_disabled &= ~(1 << irq_idx); + /* Enable the CA1 interrupt when no slot is disabled. */ + if (!nubus_disabled) + via2[gIER] = IER_SET_BIT(1); + break; + case MAC_VIA_IICI: + /* On RBV, enable the slot interrupt. + * SIER works like IER. + */ + via2[rSIER] = IER_SET_BIT(irq_idx); + break; + } + } +} + +void via_irq_disable(int irq) { + int irq_src = IRQ_SRC(irq); + int irq_idx = IRQ_IDX(irq); + + if (irq_src == 1) { + via1[vIER] = IER_CLR_BIT(irq_idx); + } else if (irq_src == 2) { + via2[gIER] = IER_CLR_BIT(irq_idx); + } else if (irq_src == 7) { + switch (macintosh_config->via_type) { + case MAC_VIA_II: + case MAC_VIA_QUADRA: + nubus_disabled |= 1 << irq_idx; + if (nubus_disabled) + via2[gIER] = IER_CLR_BIT(1); + break; + case MAC_VIA_IICI: + via2[rSIER] = IER_CLR_BIT(irq_idx); + break; + } + } +} + +void via1_set_head(int head) +{ + if (head == 0) + via1[vBufA] &= ~VIA1A_vHeadSel; + else + via1[vBufA] |= VIA1A_vHeadSel; +} +EXPORT_SYMBOL(via1_set_head); + +int via2_scsi_drq_pending(void) +{ + return via2[gIFR] & (1 << IRQ_IDX(IRQ_MAC_SCSIDRQ)); +} +EXPORT_SYMBOL(via2_scsi_drq_pending); + +/* timer and clock source */ + +#define VIA_CLOCK_FREQ 783360 /* VIA "phase 2" clock in Hz */ +#define VIA_TIMER_CYCLES (VIA_CLOCK_FREQ / HZ) /* clock cycles per jiffy */ + +#define VIA_TC (VIA_TIMER_CYCLES - 2) /* including 0 and -1 */ +#define VIA_TC_LOW (VIA_TC & 0xFF) +#define VIA_TC_HIGH (VIA_TC >> 8) + +static u64 mac_read_clk(struct clocksource *cs); + +static struct clocksource mac_clk = { + .name = "via1", + .rating = 250, + .read = mac_read_clk, + .mask = CLOCKSOURCE_MASK(32), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +static u32 clk_total, clk_offset; + +static irqreturn_t via_timer_handler(int irq, void *dev_id) +{ + clk_total += VIA_TIMER_CYCLES; + clk_offset = 0; + legacy_timer_tick(1); + + return IRQ_HANDLED; +} + +void __init via_init_clock(void) +{ + if (request_irq(IRQ_MAC_TIMER_1, via_timer_handler, IRQF_TIMER, "timer", + NULL)) { + pr_err("Couldn't register %s interrupt\n", "timer"); + return; + } + + via1[vT1CL] = VIA_TC_LOW; + via1[vT1CH] = VIA_TC_HIGH; + via1[vACR] |= 0x40; + + clocksource_register_hz(&mac_clk, VIA_CLOCK_FREQ); +} + +static u64 mac_read_clk(struct clocksource *cs) +{ + unsigned long flags; + u8 count_high; + u16 count; + u32 ticks; + + /* + * Timer counter wrap-around is detected with the timer interrupt flag + * but reading the counter low byte (vT1CL) would reset the flag. + * Also, accessing both counter registers is essentially a data race. + * These problems are avoided by ignoring the low byte. Clock accuracy + * is 256 times worse (error can reach 0.327 ms) but CPU overhead is + * reduced by avoiding slow VIA register accesses. + */ + + local_irq_save(flags); + count_high = via1[vT1CH]; + if (count_high == 0xFF) + count_high = 0; + if (count_high > 0 && (via1[vIFR] & VIA_TIMER_1_INT)) + clk_offset = VIA_TIMER_CYCLES; + count = count_high << 8; + ticks = VIA_TIMER_CYCLES - count; + ticks += clk_offset + clk_total; + local_irq_restore(flags); + + return ticks; +} |