arch/i386/kernel/i8259.c

   1 #include <linux/config.h>
   2 #include <linux/errno.h>
   3 #include <linux/signal.h>
   4 #include <linux/sched.h>
   5 #include <linux/ioport.h>
   6 #include <linux/interrupt.h>
   7 #include <linux/slab.h>
   8 #include <linux/random.h>
   9 #include <linux/smp_lock.h>
  10 #include <linux/init.h>
  11 #include <linux/kernel_stat.h>
  12 #include <linux/sysdev.h>
  13 #include <linux/bitops.h>
  14
  15 #include <asm/8253pit.h>
  16 #include <asm/atomic.h>
  17 #include <asm/system.h>
  18 #include <asm/io.h>
  19 #include <asm/irq.h>
  20 #include <asm/timer.h>
  21 #include <asm/pgtable.h>
  22 #include <asm/delay.h>
  23 #include <asm/desc.h>
  24 #include <asm/apic.h>
  25 #include <asm/arch_hooks.h>
  26 #include <asm/i8259.h>
  27
  28 #include <linux/irq.h>
  29
  30 #include <io_ports.h>
  31
  32 /*
  33  * This is the 'legacy' 8259A Programmable Interrupt Controller,
  34  * present in the majority of PC/AT boxes.
  35  * plus some generic x86 specific things if generic specifics makes
  36  * any sense at all.
  37  * this file should become arch/i386/kernel/irq.c when the old irq.c
  38  * moves to arch independent land
  39  */
  40
  41 DEFINE_SPINLOCK(i8259A_lock);
  42
  43 static void end_8259A_irq (unsigned int irq)
  44 {
  45         if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)) &&
  46                                                         irq_desc[irq].action)
  47                 enable_8259A_irq(irq);
  48 }
  49
  50 #define shutdown_8259A_irq      disable_8259A_irq
  51
  52 static void mask_and_ack_8259A(unsigned int);
  53
  54 unsigned int startup_8259A_irq(unsigned int irq)
  55 {
  56         enable_8259A_irq(irq);
  57         return 0; /* never anything pending */
  58 }
  59
  60 static struct hw_interrupt_type i8259A_irq_type = {
  61         .typename = "XT-PIC",
  62         .startup = startup_8259A_irq,
  63         .shutdown = shutdown_8259A_irq,
  64         .enable = enable_8259A_irq,
  65         .disable = disable_8259A_irq,
  66         .ack = mask_and_ack_8259A,
  67         .end = end_8259A_irq,
  68 };
  69
  70 /*
  71  * 8259A PIC functions to handle ISA devices:
  72  */
  73
  74 /*
  75  * This contains the irq mask for both 8259A irq controllers,
  76  */
  77 unsigned int cached_irq_mask = 0xffff;
  78
  79 /*
  80  * Not all IRQs can be routed through the IO-APIC, eg. on certain (older)
  81  * boards the timer interrupt is not really connected to any IO-APIC pin,
  82  * it's fed to the master 8259A's IR0 line only.
  83  *
  84  * Any '1' bit in this mask means the IRQ is routed through the IO-APIC.
  85  * this 'mixed mode' IRQ handling costs nothing because it's only used
  86  * at IRQ setup time.
  87  */
  88 unsigned long io_apic_irqs;
  89
  90 void disable_8259A_irq(unsigned int irq)
  91 {
  92         unsigned int mask = 1 << irq;
  93         unsigned long flags;
  94
  95         spin_lock_irqsave(&i8259A_lock, flags);
  96         cached_irq_mask |= mask;
  97         if (irq & 8)
  98                 outb(cached_slave_mask, PIC_SLAVE_IMR);
  99         else
 100                 outb(cached_master_mask, PIC_MASTER_IMR);
 101         spin_unlock_irqrestore(&i8259A_lock, flags);
 102 }
 103
 104 void enable_8259A_irq(unsigned int irq)
 105 {
 106         unsigned int mask = ~(1 << irq);
 107         unsigned long flags;
 108
 109         spin_lock_irqsave(&i8259A_lock, flags);
 110         cached_irq_mask &= mask;
 111         if (irq & 8)
 112                 outb(cached_slave_mask, PIC_SLAVE_IMR);
 113         else
 114                 outb(cached_master_mask, PIC_MASTER_IMR);
 115         spin_unlock_irqrestore(&i8259A_lock, flags);
 116 }
 117
 118 int i8259A_irq_pending(unsigned int irq)
 119 {
 120         unsigned int mask = 1<<irq;
 121         unsigned long flags;
 122         int ret;
 123
 124         spin_lock_irqsave(&i8259A_lock, flags);
 125         if (irq < 8)
 126                 ret = inb(PIC_MASTER_CMD) & mask;
 127         else
 128                 ret = inb(PIC_SLAVE_CMD) & (mask >> 8);
 129         spin_unlock_irqrestore(&i8259A_lock, flags);
 130
 131         return ret;
 132 }
 133
 134 void make_8259A_irq(unsigned int irq)
 135 {
 136         disable_irq_nosync(irq);
 137         io_apic_irqs &= ~(1<<irq);
 138         irq_desc[irq].handler = &i8259A_irq_type;
 139         enable_irq(irq);
 140 }
 141
 142 /*
 143  * This function assumes to be called rarely. Switching between
 144  * 8259A registers is slow.
 145  * This has to be protected by the irq controller spinlock
 146  * before being called.
 147  */
 148 static inline int i8259A_irq_real(unsigned int irq)
 149 {
 150         int value;
 151         int irqmask = 1<<irq;
 152
 153         if (irq < 8) {
 154                 outb(0x0B,PIC_MASTER_CMD);      /* ISR register */
 155                 value = inb(PIC_MASTER_CMD) & irqmask;
 156                 outb(0x0A,PIC_MASTER_CMD);      /* back to the IRR register */
 157                 return value;
 158         }
 159         outb(0x0B,PIC_SLAVE_CMD);       /* ISR register */
 160         value = inb(PIC_SLAVE_CMD) & (irqmask >> 8);
 161         outb(0x0A,PIC_SLAVE_CMD);       /* back to the IRR register */
 162         return value;
 163 }
 164
 165 /*
 166  * Careful! The 8259A is a fragile beast, it pretty
 167  * much _has_ to be done exactly like this (mask it
 168  * first, _then_ send the EOI, and the order of EOI
 169  * to the two 8259s is important!
 170  */
 171 static void mask_and_ack_8259A(unsigned int irq)
 172 {
 173         unsigned int irqmask = 1 << irq;
 174         unsigned long flags;
 175
 176         spin_lock_irqsave(&i8259A_lock, flags);
 177         /*
 178          * Lightweight spurious IRQ detection. We do not want
 179          * to overdo spurious IRQ handling - it's usually a sign
 180          * of hardware problems, so we only do the checks we can
 181          * do without slowing down good hardware unnecesserily.
 182          *
 183          * Note that IRQ7 and IRQ15 (the two spurious IRQs
 184          * usually resulting from the 8259A-1|2 PICs) occur
 185          * even if the IRQ is masked in the 8259A. Thus we
 186          * can check spurious 8259A IRQs without doing the
 187          * quite slow i8259A_irq_real() call for every IRQ.
 188          * This does not cover 100% of spurious interrupts,
 189          * but should be enough to warn the user that there
 190          * is something bad going on ...
 191          */
 192         if (cached_irq_mask & irqmask)
 193                 goto spurious_8259A_irq;
 194         cached_irq_mask |= irqmask;
 195
 196 handle_real_irq:
 197         if (irq & 8) {
 198                 inb(PIC_SLAVE_IMR);     /* DUMMY - (do we need this?) */
 199                 outb(cached_slave_mask, PIC_SLAVE_IMR);
 200                 outb(0x60+(irq&7),PIC_SLAVE_CMD);/* 'Specific EOI' to slave */
 201                 outb(0x60+PIC_CASCADE_IR,PIC_MASTER_CMD); /* 'Specific EOI' to master-IRQ2 */
 202         } else {
 203                 inb(PIC_MASTER_IMR);    /* DUMMY - (do we need this?) */
 204                 outb(cached_master_mask, PIC_MASTER_IMR);
 205                 outb(0x60+irq,PIC_MASTER_CMD);  /* 'Specific EOI to master */
 206         }
 207         spin_unlock_irqrestore(&i8259A_lock, flags);
 208         return;
 209
 210 spurious_8259A_irq:
 211         /*
 212          * this is the slow path - should happen rarely.
 213          */
 214         if (i8259A_irq_real(irq))
 215                 /*
 216                  * oops, the IRQ _is_ in service according to the
 217                  * 8259A - not spurious, go handle it.
 218                  */
 219                 goto handle_real_irq;
 220
 221         {
 222                 static int spurious_irq_mask;
 223                 /*
 224                  * At this point we can be sure the IRQ is spurious,
 225                  * lets ACK and report it. [once per IRQ]
 226                  */
 227                 if (!(spurious_irq_mask & irqmask)) {
 228                         printk(KERN_DEBUG "spurious 8259A interrupt: IRQ%d.\n", irq);
 229                         spurious_irq_mask |= irqmask;
 230                 }
 231                 atomic_inc(&irq_err_count);
 232                 /*
 233                  * Theoretically we do not have to handle this IRQ,
 234                  * but in Linux this does not cause problems and is
 235                  * simpler for us.
 236                  */
 237                 goto handle_real_irq;
 238         }
 239 }
 240
 241 static char irq_trigger[2];
 242 /**
 243  * ELCR registers (0x4d0, 0x4d1) control edge/level of IRQ
 244  */
 245 static void restore_ELCR(char *trigger)
 246 {
 247         outb(trigger[0], 0x4d0);
 248         outb(trigger[1], 0x4d1);
 249 }
 250
 251 static void save_ELCR(char *trigger)
 252 {
 253         /* IRQ 0,1,2,8,13 are marked as reserved */
 254         trigger[0] = inb(0x4d0) & 0xF8;
 255         trigger[1] = inb(0x4d1) & 0xDE;
 256 }
 257
 258 static int i8259A_resume(struct sys_device *dev)
 259 {
 260         init_8259A(0);
 261         restore_ELCR(irq_trigger);
 262         return 0;
 263 }
 264
 265 static int i8259A_suspend(struct sys_device *dev, u32 state)
 266 {
 267         save_ELCR(irq_trigger);
 268         return 0;
 269 }
 270
 271 static struct sysdev_class i8259_sysdev_class = {
 272         set_kset_name("i8259"),
 273         .suspend = i8259A_suspend,
 274         .resume = i8259A_resume,
 275 };
 276
 277 static struct sys_device device_i8259A = {
 278         .id     = 0,
 279         .cls    = &i8259_sysdev_class,
 280 };
 281
 282 static int __init i8259A_init_sysfs(void)
 283 {
 284         int error = sysdev_class_register(&i8259_sysdev_class);
 285         if (!error)
 286                 error = sysdev_register(&device_i8259A);
 287         return error;
 288 }
 289
 290 device_initcall(i8259A_init_sysfs);
 291
 292 void init_8259A(int auto_eoi)
 293 {
 294         unsigned long flags;
 295
 296         spin_lock_irqsave(&i8259A_lock, flags);
 297
 298         outb(0xff, PIC_MASTER_IMR);     /* mask all of 8259A-1 */
 299         outb(0xff, PIC_SLAVE_IMR);      /* mask all of 8259A-2 */
 300
 301         /*
 302          * outb_p - this has to work on a wide range of PC hardware.
 303          */
 304         outb_p(0x11, PIC_MASTER_CMD);   /* ICW1: select 8259A-1 init */
 305         outb_p(0x20 + 0, PIC_MASTER_IMR);       /* ICW2: 8259A-1 IR0-7 mapped to 0x20-0x27 */
 306         outb_p(1U << PIC_CASCADE_IR, PIC_MASTER_IMR);   /* 8259A-1 (the master) has a slave on IR2 */
 307         if (auto_eoi)   /* master does Auto EOI */
 308                 outb_p(MASTER_ICW4_DEFAULT | PIC_ICW4_AEOI, PIC_MASTER_IMR);
 309         else            /* master expects normal EOI */
 310                 outb_p(MASTER_ICW4_DEFAULT, PIC_MASTER_IMR);
 311
 312         outb_p(0x11, PIC_SLAVE_CMD);    /* ICW1: select 8259A-2 init */
 313         outb_p(0x20 + 8, PIC_SLAVE_IMR);        /* ICW2: 8259A-2 IR0-7 mapped to 0x28-0x2f */
 314         outb_p(PIC_CASCADE_IR, PIC_SLAVE_IMR);  /* 8259A-2 is a slave on master's IR2 */
 315         outb_p(SLAVE_ICW4_DEFAULT, PIC_SLAVE_IMR); /* (slave's support for AEOI in flat mode is to be investigated) */
 316         if (auto_eoi)
 317                 /*
 318                  * in AEOI mode we just have to mask the interrupt
 319                  * when acking.
 320                  */
 321                 i8259A_irq_type.ack = disable_8259A_irq;
 322         else
 323                 i8259A_irq_type.ack = mask_and_ack_8259A;
 324
 325         udelay(100);            /* wait for 8259A to initialize */
 326
 327         outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */
 328         outb(cached_slave_mask, PIC_SLAVE_IMR);   /* restore slave IRQ mask */
 329
 330         spin_unlock_irqrestore(&i8259A_lock, flags);
 331 }
 332
 333 /*
 334  * Note that on a 486, we don't want to do a SIGFPE on an irq13
 335  * as the irq is unreliable, and exception 16 works correctly
 336  * (ie as explained in the intel literature). On a 386, you
 337  * can't use exception 16 due to bad IBM design, so we have to
 338  * rely on the less exact irq13.
 339  *
 340  * Careful.. Not only is IRQ13 unreliable, but it is also
 341  * leads to races. IBM designers who came up with it should
 342  * be shot.
 343  */
 344
 345
 346 static irqreturn_t math_error_irq(int cpl, void *dev_id, struct pt_regs *regs)
 347 {
 348         extern void math_error(void __user *);
 349         outb(0,0xF0);
 350         if (ignore_fpu_irq || !boot_cpu_data.hard_math)
 351                 return IRQ_NONE;
 352         math_error((void __user *)regs->eip);
 353         return IRQ_HANDLED;
 354 }
 355
 356 /*
 357  * New motherboards sometimes make IRQ 13 be a PCI interrupt,
 358  * so allow interrupt sharing.
 359  */
 360 static struct irqaction fpu_irq = { math_error_irq, 0, CPU_MASK_NONE, "fpu", NULL, NULL };
 361
 362 void __init init_ISA_irqs (void)
 363 {
 364         int i;
 365
 366 #ifdef CONFIG_X86_LOCAL_APIC
 367         init_bsp_APIC();
 368 #endif
 369         init_8259A(0);
 370
 371         for (i = 0; i < NR_IRQS; i++) {
 372                 irq_desc[i].status = IRQ_DISABLED;
 373                 irq_desc[i].action = NULL;
 374                 irq_desc[i].depth = 1;
 375
 376                 if (i < 16) {
 377                         /*
 378                          * 16 old-style INTA-cycle interrupts:
 379                          */
 380                         irq_desc[i].handler = &i8259A_irq_type;
 381                 } else {
 382                         /*
 383                          * 'high' PCI IRQs filled in on demand
 384                          */
 385                         irq_desc[i].handler = &no_irq_type;
 386                 }
 387         }
 388 }
 389
 390 void __init init_IRQ(void)
 391 {
 392         int i;
 393
 394         /* all the set up before the call gates are initialised */
 395         pre_intr_init_hook();
 396
 397         /*
 398          * Cover the whole vector space, no vector can escape
 399          * us. (some of these will be overridden and become
 400          * 'special' SMP interrupts)
 401          */
 402         for (i = 0; i < (NR_VECTORS - FIRST_EXTERNAL_VECTOR); i++) {
 403                 int vector = FIRST_EXTERNAL_VECTOR + i;
 404                 if (i >= NR_IRQS)
 405                         break;
 406                 if (vector != SYSCALL_VECTOR)
 407                         set_intr_gate(vector, interrupt[i]);
 408         }
 409
 410         /* setup after call gates are initialised (usually add in
 411          * the architecture specific gates)
 412          */
 413         intr_init_hook();
 414
 415         /*
 416          * Set the clock to HZ Hz, we already have a valid
 417          * vector now:
 418          */
 419         setup_pit_timer();
 420
 421         /*
 422          * External FPU? Set up irq13 if so, for
 423          * original braindamaged IBM FERR coupling.
 424          */
 425         if (boot_cpu_data.hard_math && !cpu_has_fpu)
 426                 setup_irq(FPU_IRQ, &fpu_irq);
 427
 428         irq_ctx_init(smp_processor_id());
 429 }