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_name(irq, &i8259A_chip, handle_level_irq,
 115                                       i8259A_chip.name);
 116         enable_irq(irq);
 117 }
 118
 119 /*
 120  * This function assumes to be called rarely. Switching between
 121  * 8259A registers is slow.
 122  * This has to be protected by the irq controller spinlock
 123  * before being called.
 124  */
 125 static inline int i8259A_irq_real(unsigned int irq)
 126 {
 127         int value;
 128         int irqmask = 1<<irq;
 129
 130         if (irq < 8) {
 131                 outb(0x0B, PIC_MASTER_CMD);     /* ISR register */
 132                 value = inb(PIC_MASTER_CMD) & irqmask;
 133                 outb(0x0A, PIC_MASTER_CMD);     /* back to the IRR register */
 134                 return value;
 135         }
 136         outb(0x0B, PIC_SLAVE_CMD);      /* ISR register */
 137         value = inb(PIC_SLAVE_CMD) & (irqmask >> 8);
 138         outb(0x0A, PIC_SLAVE_CMD);      /* back to the IRR register */
 139         return value;
 140 }
 141
 142 /*
 143  * Careful! The 8259A is a fragile beast, it pretty
 144  * much _has_ to be done exactly like this (mask it
 145  * first, _then_ send the EOI, and the order of EOI
 146  * to the two 8259s is important!
 147  */
 148 static void mask_and_ack_8259A(struct irq_data *data)
 149 {
 150         unsigned int irq = data->irq;
 151         unsigned int irqmask = 1 << irq;
 152         unsigned long flags;
 153
 154         raw_spin_lock_irqsave(&i8259A_lock, flags);
 155         /*
 156          * Lightweight spurious IRQ detection. We do not want
 157          * to overdo spurious IRQ handling - it's usually a sign
 158          * of hardware problems, so we only do the checks we can
 159          * do without slowing down good hardware unnecessarily.
 160          *
 161          * Note that IRQ7 and IRQ15 (the two spurious IRQs
 162          * usually resulting from the 8259A-1|2 PICs) occur
 163          * even if the IRQ is masked in the 8259A. Thus we
 164          * can check spurious 8259A IRQs without doing the
 165          * quite slow i8259A_irq_real() call for every IRQ.
 166          * This does not cover 100% of spurious interrupts,
 167          * but should be enough to warn the user that there
 168          * is something bad going on ...
 169          */
 170         if (cached_irq_mask & irqmask)
 171                 goto spurious_8259A_irq;
 172         cached_irq_mask |= irqmask;
 173
 174 handle_real_irq:
 175         if (irq & 8) {
 176                 inb(PIC_SLAVE_IMR);     /* DUMMY - (do we need this?) */
 177                 outb(cached_slave_mask, PIC_SLAVE_IMR);
 178                 /* 'Specific EOI' to slave */
 179                 outb(0x60+(irq&7), PIC_SLAVE_CMD);
 180                  /* 'Specific EOI' to master-IRQ2 */
 181                 outb(0x60+PIC_CASCADE_IR, PIC_MASTER_CMD);
 182         } else {
 183                 inb(PIC_MASTER_IMR);    /* DUMMY - (do we need this?) */
 184                 outb(cached_master_mask, PIC_MASTER_IMR);
 185                 outb(0x60+irq, PIC_MASTER_CMD); /* 'Specific EOI to master */
 186         }
 187         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
 188         return;
 189
 190 spurious_8259A_irq:
 191         /*
 192          * this is the slow path - should happen rarely.
 193          */
 194         if (i8259A_irq_real(irq))
 195                 /*
 196                  * oops, the IRQ _is_ in service according to the
 197                  * 8259A - not spurious, go handle it.
 198                  */
 199                 goto handle_real_irq;
 200
 201         {
 202                 static int spurious_irq_mask;
 203                 /*
 204                  * At this point we can be sure the IRQ is spurious,
 205                  * lets ACK and report it. [once per IRQ]
 206                  */
 207                 if (!(spurious_irq_mask & irqmask)) {
 208                         printk(KERN_DEBUG
 209                                "spurious 8259A interrupt: IRQ%d.\n", irq);
 210                         spurious_irq_mask |= irqmask;
 211                 }
 212                 atomic_inc(&irq_err_count);
 213                 /*
 214                  * Theoretically we do not have to handle this IRQ,
 215                  * but in Linux this does not cause problems and is
 216                  * simpler for us.
 217                  */
 218                 goto handle_real_irq;
 219         }
 220 }
 221
 222 struct irq_chip i8259A_chip = {
 223         .name           = "XT-PIC",
 224         .irq_mask       = disable_8259A_irq,
 225         .irq_disable    = disable_8259A_irq,
 226         .irq_unmask     = enable_8259A_irq,
 227         .irq_mask_ack   = mask_and_ack_8259A,
 228 };
 229
 230 static char irq_trigger[2];
 231 /**
 232  * ELCR registers (0x4d0, 0x4d1) control edge/level of IRQ
 233  */
 234 static void restore_ELCR(char *trigger)
 235 {
 236         outb(trigger[0], 0x4d0);
 237         outb(trigger[1], 0x4d1);
 238 }
 239
 240 static void save_ELCR(char *trigger)
 241 {
 242         /* IRQ 0,1,2,8,13 are marked as reserved */
 243         trigger[0] = inb(0x4d0) & 0xF8;
 244         trigger[1] = inb(0x4d1) & 0xDE;
 245 }
 246
 247 static void i8259A_resume(void)
 248 {
 249         init_8259A(i8259A_auto_eoi);
 250         restore_ELCR(irq_trigger);
 251 }
 252
 253 static int i8259A_suspend(void)
 254 {
 255         save_ELCR(irq_trigger);
 256         return 0;
 257 }
 258
 259 static void i8259A_shutdown(void)
 260 {
 261         /* Put the i8259A into a quiescent state that
 262          * the kernel initialization code can get it
 263          * out of.
 264          */
 265         outb(0xff, PIC_MASTER_IMR);     /* mask all of 8259A-1 */
 266         outb(0xff, PIC_SLAVE_IMR);      /* mask all of 8259A-2 */
 267 }
 268
 269 static struct syscore_ops i8259_syscore_ops = {
 270         .suspend = i8259A_suspend,
 271         .resume = i8259A_resume,
 272         .shutdown = i8259A_shutdown,
 273 };
 274
 275 static void mask_8259A(void)
 276 {
 277         unsigned long flags;
 278
 279         raw_spin_lock_irqsave(&i8259A_lock, flags);
 280
 281         outb(0xff, PIC_MASTER_IMR);     /* mask all of 8259A-1 */
 282         outb(0xff, PIC_SLAVE_IMR);      /* mask all of 8259A-2 */
 283
 284         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
 285 }
 286
 287 static void unmask_8259A(void)
 288 {
 289         unsigned long flags;
 290
 291         raw_spin_lock_irqsave(&i8259A_lock, flags);
 292
 293         outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */
 294         outb(cached_slave_mask, PIC_SLAVE_IMR);   /* restore slave IRQ mask */
 295
 296         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
 297 }
 298
 299 static void init_8259A(int auto_eoi)
 300 {
 301         unsigned long flags;
 302
 303         i8259A_auto_eoi = auto_eoi;
 304
 305         raw_spin_lock_irqsave(&i8259A_lock, flags);
 306
 307         outb(0xff, PIC_MASTER_IMR);     /* mask all of 8259A-1 */
 308         outb(0xff, PIC_SLAVE_IMR);      /* mask all of 8259A-2 */
 309
 310         /*
 311          * outb_pic - this has to work on a wide range of PC hardware.
 312          */
 313         outb_pic(0x11, PIC_MASTER_CMD); /* ICW1: select 8259A-1 init */
 314
 315         /* ICW2: 8259A-1 IR0-7 mapped to 0x30-0x37 */
 316         outb_pic(IRQ0_VECTOR, PIC_MASTER_IMR);
 317
 318         /* 8259A-1 (the master) has a slave on IR2 */
 319         outb_pic(1U << PIC_CASCADE_IR, PIC_MASTER_IMR);
 320
 321         if (auto_eoi)   /* master does Auto EOI */
 322                 outb_pic(MASTER_ICW4_DEFAULT | PIC_ICW4_AEOI, PIC_MASTER_IMR);
 323         else            /* master expects normal EOI */
 324                 outb_pic(MASTER_ICW4_DEFAULT, PIC_MASTER_IMR);
 325
 326         outb_pic(0x11, PIC_SLAVE_CMD);  /* ICW1: select 8259A-2 init */
 327
 328         /* ICW2: 8259A-2 IR0-7 mapped to IRQ8_VECTOR */
 329         outb_pic(IRQ8_VECTOR, PIC_SLAVE_IMR);
 330         /* 8259A-2 is a slave on master's IR2 */
 331         outb_pic(PIC_CASCADE_IR, PIC_SLAVE_IMR);
 332         /* (slave's support for AEOI in flat mode is to be investigated) */
 333         outb_pic(SLAVE_ICW4_DEFAULT, PIC_SLAVE_IMR);
 334
 335         if (auto_eoi)
 336                 /*
 337                  * In AEOI mode we just have to mask the interrupt
 338                  * when acking.
 339                  */
 340                 i8259A_chip.irq_mask_ack = disable_8259A_irq;
 341         else
 342                 i8259A_chip.irq_mask_ack = mask_and_ack_8259A;
 343
 344         udelay(100);            /* wait for 8259A to initialize */
 345
 346         outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */
 347         outb(cached_slave_mask, PIC_SLAVE_IMR);   /* restore slave IRQ mask */
 348
 349         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
 350 }
 351
 352 /*
 353  * make i8259 a driver so that we can select pic functions at run time. the goal
 354  * is to make x86 binary compatible among pc compatible and non-pc compatible
 355  * platforms, such as x86 MID.
 356  */
 357
 358 static void legacy_pic_noop(void) { };
 359 static void legacy_pic_uint_noop(unsigned int unused) { };
 360 static void legacy_pic_int_noop(int unused) { };
 361 static int legacy_pic_irq_pending_noop(unsigned int irq)
 362 {
 363         return 0;
 364 }
 365
 366 struct legacy_pic null_legacy_pic = {
 367         .nr_legacy_irqs = 0,
 368         .chip = &dummy_irq_chip,
 369         .mask = legacy_pic_uint_noop,
 370         .unmask = legacy_pic_uint_noop,
 371         .mask_all = legacy_pic_noop,
 372         .restore_mask = legacy_pic_noop,
 373         .init = legacy_pic_int_noop,
 374         .irq_pending = legacy_pic_irq_pending_noop,
 375         .make_irq = legacy_pic_uint_noop,
 376 };
 377
 378 struct legacy_pic default_legacy_pic = {
 379         .nr_legacy_irqs = NR_IRQS_LEGACY,
 380         .chip  = &i8259A_chip,
 381         .mask = mask_8259A_irq,
 382         .unmask = unmask_8259A_irq,
 383         .mask_all = mask_8259A,
 384         .restore_mask = unmask_8259A,
 385         .init = init_8259A,
 386         .irq_pending = i8259A_irq_pending,
 387         .make_irq = make_8259A_irq,
 388 };
 389
 390 struct legacy_pic *legacy_pic = &default_legacy_pic;
 391
 392 static int __init i8259A_init_ops(void)
 393 {
 394         if (legacy_pic == &default_legacy_pic)
 395                 register_syscore_ops(&i8259_syscore_ops);
 396
 397         return 0;
 398 }
 399
 400 device_initcall(i8259A_init_ops);