arch/x86/kernel/i8259.c

   1 #include <linux/linkage.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/timex.h>
   8 #include <linux/random.h>
   9 #include <linux/init.h>
  10 #include <linux/kernel_stat.h>
  11 #include <linux/syscore_ops.h>
  12 #include <linux/bitops.h>
  13 #include <linux/acpi.h>
  14 #include <linux/io.h>
  15 #include <linux/delay.h>
  16
  17 #include <linux/atomic.h>
  18 #include <asm/timer.h>
  19 #include <asm/hw_irq.h>
  20 #include <asm/pgtable.h>
  21 #include <asm/desc.h>
  22 #include <asm/apic.h>
  23 #include <asm/i8259.h>
  24
  25 /*
  26  * This is the 'legacy' 8259A Programmable Interrupt Controller,
  27  * present in the majority of PC/AT boxes.
  28  * plus some generic x86 specific things if generic specifics makes
  29  * any sense at all.
  30  */
  31 static void init_8259A(int auto_eoi);
  32
  33 static int i8259A_auto_eoi;
  34 DEFINE_RAW_SPINLOCK(i8259A_lock);
  35
  36 /*
  37  * 8259A PIC functions to handle ISA devices:
  38  */
  39
  40 /*
  41  * This contains the irq mask for both 8259A irq controllers,
  42  */
  43 unsigned int cached_irq_mask = 0xffff;
  44
  45 /*
  46  * Not all IRQs can be routed through the IO-APIC, eg. on certain (older)
  47  * boards the timer interrupt is not really connected to any IO-APIC pin,
  48  * it's fed to the master 8259A's IR0 line only.
  49  *
  50  * Any '1' bit in this mask means the IRQ is routed through the IO-APIC.
  51  * this 'mixed mode' IRQ handling costs nothing because it's only used
  52  * at IRQ setup time.
  53  */
  54 unsigned long io_apic_irqs;
  55
  56 static void mask_8259A_irq(unsigned int irq)
  57 {
  58         unsigned int mask = 1 << irq;
  59         unsigned long flags;
  60
  61         raw_spin_lock_irqsave(&i8259A_lock, flags);
  62         cached_irq_mask |= mask;
  63         if (irq & 8)
  64                 outb(cached_slave_mask, PIC_SLAVE_IMR);
  65         else
  66                 outb(cached_master_mask, PIC_MASTER_IMR);
  67         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
  68 }
  69
  70 static void disable_8259A_irq(struct irq_data *data)
  71 {
  72         mask_8259A_irq(data->irq);
  73 }
  74
  75 static void unmask_8259A_irq(unsigned int irq)
  76 {
  77         unsigned int mask = ~(1 << irq);
  78         unsigned long flags;
  79
  80         raw_spin_lock_irqsave(&i8259A_lock, flags);
  81         cached_irq_mask &= mask;
  82         if (irq & 8)
  83                 outb(cached_slave_mask, PIC_SLAVE_IMR);
  84         else
  85                 outb(cached_master_mask, PIC_MASTER_IMR);
  86         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
  87 }
  88
  89 static void enable_8259A_irq(struct irq_data *data)
  90 {
  91         unmask_8259A_irq(data->irq);
  92 }
  93
  94 static int i8259A_irq_pending(unsigned int irq)
  95 {
  96         unsigned int mask = 1<<irq;
  97         unsigned long flags;
  98         int ret;
  99
 100         raw_spin_lock_irqsave(&i8259A_lock, flags);
 101         if (irq < 8)
 102                 ret = inb(PIC_MASTER_CMD) & mask;
 103         else
 104                 ret = inb(PIC_SLAVE_CMD) & (mask >> 8);
 105         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
 106
 107         return ret;
 108 }
 109
 110 static void make_8259A_irq(unsigned int irq)
 111 {
 112         disable_irq_nosync(irq);
 113         io_apic_irqs &= ~(1<<irq);
 114         irq_set_chip_and_handler(irq, &i8259A_chip, handle_level_irq);
 115         enable_irq(irq);
 116 }
 117
 118 /*
 119  * This function assumes to be called rarely. Switching between
 120  * 8259A registers is slow.
 121  * This has to be protected by the irq controller spinlock
 122  * before being called.
 123  */
 124 static inline int i8259A_irq_real(unsigned int irq)
 125 {
 126         int value;
 127         int irqmask = 1<<irq;
 128
 129         if (irq < 8) {
 130                 outb(0x0B, PIC_MASTER_CMD);     /* ISR register */
 131                 value = inb(PIC_MASTER_CMD) & irqmask;
 132                 outb(0x0A, PIC_MASTER_CMD);     /* back to the IRR register */
 133                 return value;
 134         }
 135         outb(0x0B, PIC_SLAVE_CMD);      /* ISR register */
 136         value = inb(PIC_SLAVE_CMD) & (irqmask >> 8);
 137         outb(0x0A, PIC_SLAVE_CMD);      /* back to the IRR register */
 138         return value;
 139 }
 140
 141 /*
 142  * Careful! The 8259A is a fragile beast, it pretty
 143  * much _has_ to be done exactly like this (mask it
 144  * first, _then_ send the EOI, and the order of EOI
 145  * to the two 8259s is important!
 146  */
 147 static void mask_and_ack_8259A(struct irq_data *data)
 148 {
 149         unsigned int irq = data->irq;
 150         unsigned int irqmask = 1 << irq;
 151         unsigned long flags;
 152
 153         raw_spin_lock_irqsave(&i8259A_lock, flags);
 154         /*
 155          * Lightweight spurious IRQ detection. We do not want
 156          * to overdo spurious IRQ handling - it's usually a sign
 157          * of hardware problems, so we only do the checks we can
 158          * do without slowing down good hardware unnecessarily.
 159          *
 160          * Note that IRQ7 and IRQ15 (the two spurious IRQs
 161          * usually resulting from the 8259A-1|2 PICs) occur
 162          * even if the IRQ is masked in the 8259A. Thus we
 163          * can check spurious 8259A IRQs without doing the
 164          * quite slow i8259A_irq_real() call for every IRQ.
 165          * This does not cover 100% of spurious interrupts,
 166          * but should be enough to warn the user that there
 167          * is something bad going on ...
 168          */
 169         if (cached_irq_mask & irqmask)
 170                 goto spurious_8259A_irq;
 171         cached_irq_mask |= irqmask;
 172
 173 handle_real_irq:
 174         if (irq & 8) {
 175                 inb(PIC_SLAVE_IMR);     /* DUMMY - (do we need this?) */
 176                 outb(cached_slave_mask, PIC_SLAVE_IMR);
 177                 /* 'Specific EOI' to slave */
 178                 outb(0x60+(irq&7), PIC_SLAVE_CMD);
 179                  /* 'Specific EOI' to master-IRQ2 */
 180                 outb(0x60+PIC_CASCADE_IR, PIC_MASTER_CMD);
 181         } else {
 182                 inb(PIC_MASTER_IMR);    /* DUMMY - (do we need this?) */
 183                 outb(cached_master_mask, PIC_MASTER_IMR);
 184                 outb(0x60+irq, PIC_MASTER_CMD); /* 'Specific EOI to master */
 185         }
 186         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
 187         return;
 188
 189 spurious_8259A_irq:
 190         /*
 191          * this is the slow path - should happen rarely.
 192          */
 193         if (i8259A_irq_real(irq))
 194                 /*
 195                  * oops, the IRQ _is_ in service according to the
 196                  * 8259A - not spurious, go handle it.
 197                  */
 198                 goto handle_real_irq;
 199
 200         {
 201                 static int spurious_irq_mask;
 202                 /*
 203                  * At this point we can be sure the IRQ is spurious,
 204                  * lets ACK and report it. [once per IRQ]
 205                  */
 206                 if (!(spurious_irq_mask & irqmask)) {
 207                         printk(KERN_DEBUG
 208                                "spurious 8259A interrupt: IRQ%d.\n", irq);
 209                         spurious_irq_mask |= irqmask;
 210                 }
 211                 atomic_inc(&irq_err_count);
 212                 /*
 213                  * Theoretically we do not have to handle this IRQ,
 214                  * but in Linux this does not cause problems and is
 215                  * simpler for us.
 216                  */
 217                 goto handle_real_irq;
 218         }
 219 }
 220
 221 struct irq_chip i8259A_chip = {
 222         .name           = "XT-PIC",
 223         .irq_mask       = disable_8259A_irq,
 224         .irq_disable    = disable_8259A_irq,
 225         .irq_unmask     = enable_8259A_irq,
 226         .irq_mask_ack   = mask_and_ack_8259A,
 227 };
 228
 229 static char irq_trigger[2];
 230 /**
 231  * ELCR registers (0x4d0, 0x4d1) control edge/level of IRQ
 232  */
 233 static void restore_ELCR(char *trigger)
 234 {
 235         outb(trigger[0], 0x4d0);
 236         outb(trigger[1], 0x4d1);
 237 }
 238
 239 static void save_ELCR(char *trigger)
 240 {
 241         /* IRQ 0,1,2,8,13 are marked as reserved */
 242         trigger[0] = inb(0x4d0) & 0xF8;
 243         trigger[1] = inb(0x4d1) & 0xDE;
 244 }
 245
 246 static void i8259A_resume(void)
 247 {
 248         init_8259A(i8259A_auto_eoi);
 249         restore_ELCR(irq_trigger);
 250 }
 251
 252 static int i8259A_suspend(void)
 253 {
 254         save_ELCR(irq_trigger);
 255         return 0;
 256 }
 257
 258 static void i8259A_shutdown(void)
 259 {
 260         /* Put the i8259A into a quiescent state that
 261          * the kernel initialization code can get it
 262          * out of.
 263          */
 264         outb(0xff, PIC_MASTER_IMR);     /* mask all of 8259A-1 */
 265         outb(0xff, PIC_SLAVE_IMR);      /* mask all of 8259A-2 */
 266 }
 267
 268 static struct syscore_ops i8259_syscore_ops = {
 269         .suspend = i8259A_suspend,
 270         .resume = i8259A_resume,
 271         .shutdown = i8259A_shutdown,
 272 };
 273
 274 static void mask_8259A(void)
 275 {
 276         unsigned long flags;
 277
 278         raw_spin_lock_irqsave(&i8259A_lock, flags);
 279
 280         outb(0xff, PIC_MASTER_IMR);     /* mask all of 8259A-1 */
 281         outb(0xff, PIC_SLAVE_IMR);      /* mask all of 8259A-2 */
 282
 283         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
 284 }
 285
 286 static void unmask_8259A(void)
 287 {
 288         unsigned long flags;
 289
 290         raw_spin_lock_irqsave(&i8259A_lock, flags);
 291
 292         outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */
 293         outb(cached_slave_mask, PIC_SLAVE_IMR);   /* restore slave IRQ mask */
 294
 295         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
 296 }
 297
 298 static int probe_8259A(void)
 299 {
 300         unsigned long flags;
 301         unsigned char probe_val = ~(1 << PIC_CASCADE_IR);
 302         unsigned char new_val;
 303         /*
 304          * Check to see if we have a PIC.
 305          * Mask all except the cascade and read
 306          * back the value we just wrote. If we don't
 307          * have a PIC, we will read 0xff as opposed to the
 308          * value we wrote.
 309          */
 310         raw_spin_lock_irqsave(&i8259A_lock, flags);
 311
 312         outb(0xff, PIC_SLAVE_IMR);      /* mask all of 8259A-2 */
 313         outb(probe_val, PIC_MASTER_IMR);
 314         new_val = inb(PIC_MASTER_IMR);
 315         if (new_val != probe_val) {
 316                 printk(KERN_INFO "Using NULL legacy PIC\n");
 317                 legacy_pic = &null_legacy_pic;
 318         }
 319
 320         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
 321         return nr_legacy_irqs();
 322 }
 323
 324 static void init_8259A(int auto_eoi)
 325 {
 326         unsigned long flags;
 327
 328         i8259A_auto_eoi = auto_eoi;
 329
 330         raw_spin_lock_irqsave(&i8259A_lock, flags);
 331
 332         outb(0xff, PIC_MASTER_IMR);     /* mask all of 8259A-1 */
 333
 334         /*
 335          * outb_pic - this has to work on a wide range of PC hardware.
 336          */
 337         outb_pic(0x11, PIC_MASTER_CMD); /* ICW1: select 8259A-1 init */
 338
 339         /* ICW2: 8259A-1 IR0-7 mapped to ISA_IRQ_VECTOR(0) */
 340         outb_pic(ISA_IRQ_VECTOR(0), PIC_MASTER_IMR);
 341
 342         /* 8259A-1 (the master) has a slave on IR2 */
 343         outb_pic(1U << PIC_CASCADE_IR, PIC_MASTER_IMR);
 344
 345         if (auto_eoi)   /* master does Auto EOI */
 346                 outb_pic(MASTER_ICW4_DEFAULT | PIC_ICW4_AEOI, PIC_MASTER_IMR);
 347         else            /* master expects normal EOI */
 348                 outb_pic(MASTER_ICW4_DEFAULT, PIC_MASTER_IMR);
 349
 350         outb_pic(0x11, PIC_SLAVE_CMD);  /* ICW1: select 8259A-2 init */
 351
 352         /* ICW2: 8259A-2 IR0-7 mapped to ISA_IRQ_VECTOR(8) */
 353         outb_pic(ISA_IRQ_VECTOR(8), PIC_SLAVE_IMR);
 354         /* 8259A-2 is a slave on master's IR2 */
 355         outb_pic(PIC_CASCADE_IR, PIC_SLAVE_IMR);
 356         /* (slave's support for AEOI in flat mode is to be investigated) */
 357         outb_pic(SLAVE_ICW4_DEFAULT, PIC_SLAVE_IMR);
 358
 359         if (auto_eoi)
 360                 /*
 361                  * In AEOI mode we just have to mask the interrupt
 362                  * when acking.
 363                  */
 364                 i8259A_chip.irq_mask_ack = disable_8259A_irq;
 365         else
 366                 i8259A_chip.irq_mask_ack = mask_and_ack_8259A;
 367
 368         udelay(100);            /* wait for 8259A to initialize */
 369
 370         outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */
 371         outb(cached_slave_mask, PIC_SLAVE_IMR);   /* restore slave IRQ mask */
 372
 373         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
 374 }
 375
 376 /*
 377  * make i8259 a driver so that we can select pic functions at run time. the goal
 378  * is to make x86 binary compatible among pc compatible and non-pc compatible
 379  * platforms, such as x86 MID.
 380  */
 381
 382 static void legacy_pic_noop(void) { };
 383 static void legacy_pic_uint_noop(unsigned int unused) { };
 384 static void legacy_pic_int_noop(int unused) { };
 385 static int legacy_pic_irq_pending_noop(unsigned int irq)
 386 {
 387         return 0;
 388 }
 389 static int legacy_pic_probe(void)
 390 {
 391         return 0;
 392 }
 393
 394 struct legacy_pic null_legacy_pic = {
 395         .nr_legacy_irqs = 0,
 396         .chip = &dummy_irq_chip,
 397         .mask = legacy_pic_uint_noop,
 398         .unmask = legacy_pic_uint_noop,
 399         .mask_all = legacy_pic_noop,
 400         .restore_mask = legacy_pic_noop,
 401         .init = legacy_pic_int_noop,
 402         .probe = legacy_pic_probe,
 403         .irq_pending = legacy_pic_irq_pending_noop,
 404         .make_irq = legacy_pic_uint_noop,
 405 };
 406
 407 struct legacy_pic default_legacy_pic = {
 408         .nr_legacy_irqs = NR_IRQS_LEGACY,
 409         .chip  = &i8259A_chip,
 410         .mask = mask_8259A_irq,
 411         .unmask = unmask_8259A_irq,
 412         .mask_all = mask_8259A,
 413         .restore_mask = unmask_8259A,
 414         .init = init_8259A,
 415         .probe = probe_8259A,
 416         .irq_pending = i8259A_irq_pending,
 417         .make_irq = make_8259A_irq,
 418 };
 419
 420 struct legacy_pic *legacy_pic = &default_legacy_pic;
 421
 422 static int __init i8259A_init_ops(void)
 423 {
 424         if (legacy_pic == &default_legacy_pic)
 425                 register_syscore_ops(&i8259_syscore_ops);
 426
 427         return 0;
 428 }
 429
 430 device_initcall(i8259A_init_ops);