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   1 /*
   2  *      linux/arch/i386/mach-visws/visws_apic.c
   3  *
   4  *      Copyright (C) 1999 Bent Hagemark, Ingo Molnar
   5  *
   6  *  SGI Visual Workstation interrupt controller
   7  *
   8  *  The Cobalt system ASIC in the Visual Workstation contains a "Cobalt" APIC
   9  *  which serves as the main interrupt controller in the system.  Non-legacy
  10  *  hardware in the system uses this controller directly.  Legacy devices
  11  *  are connected to the PIIX4 which in turn has its 8259(s) connected to
  12  *  a of the Cobalt APIC entry.
  13  *
  14  *  09/02/2000 - Updated for 2.4 by jbarnes@sgi.com
  15  *
  16  *  25/11/2002 - Updated for 2.5 by Andrey Panin <pazke@orbita1.ru>
  17  */
  18
  19 #include <linux/kernel_stat.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/init.h>
  22
  23 #include <asm/io.h>
  24 #include <asm/apic.h>
  25 #include <asm/i8259.h>
  26
  27 #include "cobalt.h"
  28 #include "irq_vectors.h"
  29
  30
  31 static DEFINE_SPINLOCK(cobalt_lock);
  32
  33 /*
  34  * Set the given Cobalt APIC Redirection Table entry to point
  35  * to the given IDT vector/index.
  36  */
  37 static inline void co_apic_set(int entry, int irq)
  38 {
  39         co_apic_write(CO_APIC_LO(entry), CO_APIC_LEVEL | (irq + FIRST_EXTERNAL_VECTOR));
  40         co_apic_write(CO_APIC_HI(entry), 0);
  41 }
  42
  43 /*
  44  * Cobalt (IO)-APIC functions to handle PCI devices.
  45  */
  46 static inline int co_apic_ide0_hack(void)
  47 {
  48         extern char visws_board_type;
  49         extern char visws_board_rev;
  50
  51         if (visws_board_type == VISWS_320 && visws_board_rev == 5)
  52                 return 5;
  53         return CO_APIC_IDE0;
  54 }
  55
  56 static int is_co_apic(unsigned int irq)
  57 {
  58         if (IS_CO_APIC(irq))
  59                 return CO_APIC(irq);
  60
  61         switch (irq) {
  62                 case 0: return CO_APIC_CPU;
  63                 case CO_IRQ_IDE0: return co_apic_ide0_hack();
  64                 case CO_IRQ_IDE1: return CO_APIC_IDE1;
  65                 default: return -1;
  66         }
  67 }
  68
  69
  70 /*
  71  * This is the SGI Cobalt (IO-)APIC:
  72  */
  73
  74 static void enable_cobalt_irq(unsigned int irq)
  75 {
  76         co_apic_set(is_co_apic(irq), irq);
  77 }
  78
  79 static void disable_cobalt_irq(unsigned int irq)
  80 {
  81         int entry = is_co_apic(irq);
  82
  83         co_apic_write(CO_APIC_LO(entry), CO_APIC_MASK);
  84         co_apic_read(CO_APIC_LO(entry));
  85 }
  86
  87 /*
  88  * "irq" really just serves to identify the device.  Here is where we
  89  * map this to the Cobalt APIC entry where it's physically wired.
  90  * This is called via request_irq -> setup_irq -> irq_desc->startup()
  91  */
  92 static unsigned int startup_cobalt_irq(unsigned int irq)
  93 {
  94         unsigned long flags;
  95
  96         spin_lock_irqsave(&cobalt_lock, flags);
  97         if ((irq_desc[irq].status & (IRQ_DISABLED | IRQ_INPROGRESS | IRQ_WAITING)))
  98                 irq_desc[irq].status &= ~(IRQ_DISABLED | IRQ_INPROGRESS | IRQ_WAITING);
  99         enable_cobalt_irq(irq);
 100         spin_unlock_irqrestore(&cobalt_lock, flags);
 101         return 0;
 102 }
 103
 104 static void ack_cobalt_irq(unsigned int irq)
 105 {
 106         unsigned long flags;
 107
 108         spin_lock_irqsave(&cobalt_lock, flags);
 109         disable_cobalt_irq(irq);
 110         apic_write(APIC_EOI, APIC_EIO_ACK);
 111         spin_unlock_irqrestore(&cobalt_lock, flags);
 112 }
 113
 114 static void end_cobalt_irq(unsigned int irq)
 115 {
 116         unsigned long flags;
 117
 118         spin_lock_irqsave(&cobalt_lock, flags);
 119         if (!(irq_desc[irq].status & (IRQ_DISABLED | IRQ_INPROGRESS)))
 120                 enable_cobalt_irq(irq);
 121         spin_unlock_irqrestore(&cobalt_lock, flags);
 122 }
 123
 124 static struct irq_chip cobalt_irq_type = {
 125         .typename =     "Cobalt-APIC",
 126         .startup =      startup_cobalt_irq,
 127         .shutdown =     disable_cobalt_irq,
 128         .enable =       enable_cobalt_irq,
 129         .disable =      disable_cobalt_irq,
 130         .ack =          ack_cobalt_irq,
 131         .end =          end_cobalt_irq,
 132 };
 133
 134
 135 /*
 136  * This is the PIIX4-based 8259 that is wired up indirectly to Cobalt
 137  * -- not the manner expected by the code in i8259.c.
 138  *
 139  * there is a 'master' physical interrupt source that gets sent to
 140  * the CPU. But in the chipset there are various 'virtual' interrupts
 141  * waiting to be handled. We represent this to Linux through a 'master'
 142  * interrupt controller type, and through a special virtual interrupt-
 143  * controller. Device drivers only see the virtual interrupt sources.
 144  */
 145 static unsigned int startup_piix4_master_irq(unsigned int irq)
 146 {
 147         init_8259A(0);
 148
 149         return startup_cobalt_irq(irq);
 150 }
 151
 152 static void end_piix4_master_irq(unsigned int irq)
 153 {
 154         unsigned long flags;
 155
 156         spin_lock_irqsave(&cobalt_lock, flags);
 157         enable_cobalt_irq(irq);
 158         spin_unlock_irqrestore(&cobalt_lock, flags);
 159 }
 160
 161 static struct irq_chip piix4_master_irq_type = {
 162         .typename =     "PIIX4-master",
 163         .startup =      startup_piix4_master_irq,
 164         .ack =          ack_cobalt_irq,
 165         .end =          end_piix4_master_irq,
 166 };
 167
 168
 169 static struct irq_chip piix4_virtual_irq_type = {
 170         .typename =     "PIIX4-virtual",
 171         .shutdown =     disable_8259A_irq,
 172         .enable =       enable_8259A_irq,
 173         .disable =      disable_8259A_irq,
 174 };
 175
 176
 177 /*
 178  * PIIX4-8259 master/virtual functions to handle interrupt requests
 179  * from legacy devices: floppy, parallel, serial, rtc.
 180  *
 181  * None of these get Cobalt APIC entries, neither do they have IDT
 182  * entries. These interrupts are purely virtual and distributed from
 183  * the 'master' interrupt source: CO_IRQ_8259.
 184  *
 185  * When the 8259 interrupts its handler figures out which of these
 186  * devices is interrupting and dispatches to its handler.
 187  *
 188  * CAREFUL: devices see the 'virtual' interrupt only. Thus disable/
 189  * enable_irq gets the right irq. This 'master' irq is never directly
 190  * manipulated by any driver.
 191  */
 192 static irqreturn_t piix4_master_intr(int irq, void *dev_id)
 193 {
 194         int realirq;
 195         irq_desc_t *desc;
 196         unsigned long flags;
 197
 198         spin_lock_irqsave(&i8259A_lock, flags);
 199
 200         /* Find out what's interrupting in the PIIX4 master 8259 */
 201         outb(0x0c, 0x20);               /* OCW3 Poll command */
 202         realirq = inb(0x20);
 203
 204         /*
 205          * Bit 7 == 0 means invalid/spurious
 206          */
 207         if (unlikely(!(realirq & 0x80)))
 208                 goto out_unlock;
 209
 210         realirq &= 7;
 211
 212         if (unlikely(realirq == 2)) {
 213                 outb(0x0c, 0xa0);
 214                 realirq = inb(0xa0);
 215
 216                 if (unlikely(!(realirq & 0x80)))
 217                         goto out_unlock;
 218
 219                 realirq = (realirq & 7) + 8;
 220         }
 221
 222         /* mask and ack interrupt */
 223         cached_irq_mask |= 1 << realirq;
 224         if (unlikely(realirq > 7)) {
 225                 inb(0xa1);
 226                 outb(cached_slave_mask, 0xa1);
 227                 outb(0x60 + (realirq & 7), 0xa0);
 228                 outb(0x60 + 2, 0x20);
 229         } else {
 230                 inb(0x21);
 231                 outb(cached_master_mask, 0x21);
 232                 outb(0x60 + realirq, 0x20);
 233         }
 234
 235         spin_unlock_irqrestore(&i8259A_lock, flags);
 236
 237         desc = irq_desc + realirq;
 238
 239         /*
 240          * handle this 'virtual interrupt' as a Cobalt one now.
 241          */
 242         kstat_cpu(smp_processor_id()).irqs[realirq]++;
 243
 244         if (likely(desc->action != NULL))
 245                 handle_IRQ_event(realirq, desc->action);
 246
 247         if (!(desc->status & IRQ_DISABLED))
 248                 enable_8259A_irq(realirq);
 249
 250         return IRQ_HANDLED;
 251
 252 out_unlock:
 253         spin_unlock_irqrestore(&i8259A_lock, flags);
 254         return IRQ_NONE;
 255 }
 256
 257 static struct irqaction master_action = {
 258         .handler =      piix4_master_intr,
 259         .name =         "PIIX4-8259",
 260 };
 261
 262 static struct irqaction cascade_action = {
 263         .handler =      no_action,
 264         .name =         "cascade",
 265 };
 266
 267
 268 void init_VISWS_APIC_irqs(void)
 269 {
 270         int i;
 271
 272         for (i = 0; i < CO_IRQ_APIC0 + CO_APIC_LAST + 1; i++) {
 273                 irq_desc[i].status = IRQ_DISABLED;
 274                 irq_desc[i].action = 0;
 275                 irq_desc[i].depth = 1;
 276
 277                 if (i == 0) {
 278                         irq_desc[i].chip = &cobalt_irq_type;
 279                 }
 280                 else if (i == CO_IRQ_IDE0) {
 281                         irq_desc[i].chip = &cobalt_irq_type;
 282                 }
 283                 else if (i == CO_IRQ_IDE1) {
 284                         irq_desc[i].chip = &cobalt_irq_type;
 285                 }
 286                 else if (i == CO_IRQ_8259) {
 287                         irq_desc[i].chip = &piix4_master_irq_type;
 288                 }
 289                 else if (i < CO_IRQ_APIC0) {
 290                         irq_desc[i].chip = &piix4_virtual_irq_type;
 291                 }
 292                 else if (IS_CO_APIC(i)) {
 293                         irq_desc[i].chip = &cobalt_irq_type;
 294                 }
 295         }
 296
 297         setup_irq(CO_IRQ_8259, &master_action);
 298         setup_irq(2, &cascade_action);
 299 }