drivers/irqchip/irq-i8259.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Code to handle x86 style IRQs plus some generic interrupt stuff.
   7  *
   8  * Copyright (C) 1992 Linus Torvalds
   9  * Copyright (C) 1994 - 2000 Ralf Baechle
  10  */
  11 #include <linux/delay.h>
  12 #include <linux/init.h>
  13 #include <linux/ioport.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/irqchip.h>
  16 #include <linux/irqdomain.h>
  17 #include <linux/kernel.h>
  18 #include <linux/of_irq.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/syscore_ops.h>
  21 #include <linux/irq.h>
  22
  23 #include <asm/i8259.h>
  24 #include <asm/io.h>
  25
  26 /*
  27  * This is the 'legacy' 8259A Programmable Interrupt Controller,
  28  * present in the majority of PC/AT boxes.
  29  * plus some generic x86 specific things if generic specifics makes
  30  * any sense at all.
  31  * this file should become arch/i386/kernel/irq.c when the old irq.c
  32  * moves to arch independent land
  33  */
  34
  35 static int i8259A_auto_eoi = -1;
  36 DEFINE_RAW_SPINLOCK(i8259A_lock);
  37 static void disable_8259A_irq(struct irq_data *d);
  38 static void enable_8259A_irq(struct irq_data *d);
  39 static void mask_and_ack_8259A(struct irq_data *d);
  40 static void init_8259A(int auto_eoi);
  41
  42 static struct irq_chip i8259A_chip = {
  43         .name                   = "XT-PIC",
  44         .irq_mask               = disable_8259A_irq,
  45         .irq_disable            = disable_8259A_irq,
  46         .irq_unmask             = enable_8259A_irq,
  47         .irq_mask_ack           = mask_and_ack_8259A,
  48 };
  49
  50 /*
  51  * 8259A PIC functions to handle ISA devices:
  52  */
  53
  54 /*
  55  * This contains the irq mask for both 8259A irq controllers,
  56  */
  57 static unsigned int cached_irq_mask = 0xffff;
  58
  59 #define cached_master_mask      (cached_irq_mask)
  60 #define cached_slave_mask       (cached_irq_mask >> 8)
  61
  62 static void disable_8259A_irq(struct irq_data *d)
  63 {
  64         unsigned int mask, irq = d->irq - I8259A_IRQ_BASE;
  65         unsigned long flags;
  66
  67         mask = 1 << irq;
  68         raw_spin_lock_irqsave(&i8259A_lock, flags);
  69         cached_irq_mask |= mask;
  70         if (irq & 8)
  71                 outb(cached_slave_mask, PIC_SLAVE_IMR);
  72         else
  73                 outb(cached_master_mask, PIC_MASTER_IMR);
  74         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
  75 }
  76
  77 static void enable_8259A_irq(struct irq_data *d)
  78 {
  79         unsigned int mask, irq = d->irq - I8259A_IRQ_BASE;
  80         unsigned long flags;
  81
  82         mask = ~(1 << irq);
  83         raw_spin_lock_irqsave(&i8259A_lock, flags);
  84         cached_irq_mask &= mask;
  85         if (irq & 8)
  86                 outb(cached_slave_mask, PIC_SLAVE_IMR);
  87         else
  88                 outb(cached_master_mask, PIC_MASTER_IMR);
  89         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
  90 }
  91
  92 int i8259A_irq_pending(unsigned int irq)
  93 {
  94         unsigned int mask;
  95         unsigned long flags;
  96         int ret;
  97
  98         irq -= I8259A_IRQ_BASE;
  99         mask = 1 << irq;
 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 void make_8259A_irq(unsigned int irq)
 111 {
 112         disable_irq_nosync(irq);
 113         irq_set_chip_and_handler(irq, &i8259A_chip, handle_level_irq);
 114         enable_irq(irq);
 115 }
 116
 117 /*
 118  * This function assumes to be called rarely. Switching between
 119  * 8259A registers is slow.
 120  * This has to be protected by the irq controller spinlock
 121  * before being called.
 122  */
 123 static inline int i8259A_irq_real(unsigned int irq)
 124 {
 125         int value;
 126         int irqmask = 1 << irq;
 127
 128         if (irq < 8) {
 129                 outb(0x0B, PIC_MASTER_CMD);     /* ISR register */
 130                 value = inb(PIC_MASTER_CMD) & irqmask;
 131                 outb(0x0A, PIC_MASTER_CMD);     /* back to the IRR register */
 132                 return value;
 133         }
 134         outb(0x0B, PIC_SLAVE_CMD);      /* ISR register */
 135         value = inb(PIC_SLAVE_CMD) & (irqmask >> 8);
 136         outb(0x0A, PIC_SLAVE_CMD);      /* back to the IRR register */
 137         return value;
 138 }
 139
 140 /*
 141  * Careful! The 8259A is a fragile beast, it pretty
 142  * much _has_ to be done exactly like this (mask it
 143  * first, _then_ send the EOI, and the order of EOI
 144  * to the two 8259s is important!
 145  */
 146 static void mask_and_ack_8259A(struct irq_data *d)
 147 {
 148         unsigned int irqmask, irq = d->irq - I8259A_IRQ_BASE;
 149         unsigned long flags;
 150
 151         irqmask = 1 << irq;
 152         raw_spin_lock_irqsave(&i8259A_lock, flags);
 153         /*
 154          * Lightweight spurious IRQ detection. We do not want
 155          * to overdo spurious IRQ handling - it's usually a sign
 156          * of hardware problems, so we only do the checks we can
 157          * do without slowing down good hardware unnecessarily.
 158          *
 159          * Note that IRQ7 and IRQ15 (the two spurious IRQs
 160          * usually resulting from the 8259A-1|2 PICs) occur
 161          * even if the IRQ is masked in the 8259A. Thus we
 162          * can check spurious 8259A IRQs without doing the
 163          * quite slow i8259A_irq_real() call for every IRQ.
 164          * This does not cover 100% of spurious interrupts,
 165          * but should be enough to warn the user that there
 166          * is something bad going on ...
 167          */
 168         if (cached_irq_mask & irqmask)
 169                 goto spurious_8259A_irq;
 170         cached_irq_mask |= irqmask;
 171
 172 handle_real_irq:
 173         if (irq & 8) {
 174                 inb(PIC_SLAVE_IMR);     /* DUMMY - (do we need this?) */
 175                 outb(cached_slave_mask, PIC_SLAVE_IMR);
 176                 outb(0x60+(irq&7), PIC_SLAVE_CMD);/* 'Specific EOI' to slave */
 177                 outb(0x60+PIC_CASCADE_IR, PIC_MASTER_CMD); /* 'Specific EOI' to master-IRQ2 */
 178         } else {
 179                 inb(PIC_MASTER_IMR);    /* DUMMY - (do we need this?) */
 180                 outb(cached_master_mask, PIC_MASTER_IMR);
 181                 outb(0x60+irq, PIC_MASTER_CMD); /* 'Specific EOI to master */
 182         }
 183         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
 184         return;
 185
 186 spurious_8259A_irq:
 187         /*
 188          * this is the slow path - should happen rarely.
 189          */
 190         if (i8259A_irq_real(irq))
 191                 /*
 192                  * oops, the IRQ _is_ in service according to the
 193                  * 8259A - not spurious, go handle it.
 194                  */
 195                 goto handle_real_irq;
 196
 197         {
 198                 static int spurious_irq_mask;
 199                 /*
 200                  * At this point we can be sure the IRQ is spurious,
 201                  * lets ACK and report it. [once per IRQ]
 202                  */
 203                 if (!(spurious_irq_mask & irqmask)) {
 204                         printk(KERN_DEBUG "spurious 8259A interrupt: IRQ%d.\n", irq);
 205                         spurious_irq_mask |= irqmask;
 206                 }
 207                 atomic_inc(&irq_err_count);
 208                 /*
 209                  * Theoretically we do not have to handle this IRQ,
 210                  * but in Linux this does not cause problems and is
 211                  * simpler for us.
 212                  */
 213                 goto handle_real_irq;
 214         }
 215 }
 216
 217 static void i8259A_resume(void)
 218 {
 219         if (i8259A_auto_eoi >= 0)
 220                 init_8259A(i8259A_auto_eoi);
 221 }
 222
 223 static void i8259A_shutdown(void)
 224 {
 225         /* Put the i8259A into a quiescent state that
 226          * the kernel initialization code can get it
 227          * out of.
 228          */
 229         if (i8259A_auto_eoi >= 0) {
 230                 outb(0xff, PIC_MASTER_IMR);     /* mask all of 8259A-1 */
 231                 outb(0xff, PIC_SLAVE_IMR);      /* mask all of 8259A-2 */
 232         }
 233 }
 234
 235 static struct syscore_ops i8259_syscore_ops = {
 236         .resume = i8259A_resume,
 237         .shutdown = i8259A_shutdown,
 238 };
 239
 240 static int __init i8259A_init_sysfs(void)
 241 {
 242         register_syscore_ops(&i8259_syscore_ops);
 243         return 0;
 244 }
 245
 246 device_initcall(i8259A_init_sysfs);
 247
 248 static void init_8259A(int auto_eoi)
 249 {
 250         unsigned long flags;
 251
 252         i8259A_auto_eoi = auto_eoi;
 253
 254         raw_spin_lock_irqsave(&i8259A_lock, flags);
 255
 256         outb(0xff, PIC_MASTER_IMR);     /* mask all of 8259A-1 */
 257         outb(0xff, PIC_SLAVE_IMR);      /* mask all of 8259A-2 */
 258
 259         /*
 260          * outb_p - this has to work on a wide range of PC hardware.
 261          */
 262         outb_p(0x11, PIC_MASTER_CMD);   /* ICW1: select 8259A-1 init */
 263         outb_p(I8259A_IRQ_BASE + 0, PIC_MASTER_IMR);    /* ICW2: 8259A-1 IR0 mapped to I8259A_IRQ_BASE + 0x00 */
 264         outb_p(1U << PIC_CASCADE_IR, PIC_MASTER_IMR);   /* 8259A-1 (the master) has a slave on IR2 */
 265         if (auto_eoi)   /* master does Auto EOI */
 266                 outb_p(MASTER_ICW4_DEFAULT | PIC_ICW4_AEOI, PIC_MASTER_IMR);
 267         else            /* master expects normal EOI */
 268                 outb_p(MASTER_ICW4_DEFAULT, PIC_MASTER_IMR);
 269
 270         outb_p(0x11, PIC_SLAVE_CMD);    /* ICW1: select 8259A-2 init */
 271         outb_p(I8259A_IRQ_BASE + 8, PIC_SLAVE_IMR);     /* ICW2: 8259A-2 IR0 mapped to I8259A_IRQ_BASE + 0x08 */
 272         outb_p(PIC_CASCADE_IR, PIC_SLAVE_IMR);  /* 8259A-2 is a slave on master's IR2 */
 273         outb_p(SLAVE_ICW4_DEFAULT, PIC_SLAVE_IMR); /* (slave's support for AEOI in flat mode is to be investigated) */
 274         if (auto_eoi)
 275                 /*
 276                  * In AEOI mode we just have to mask the interrupt
 277                  * when acking.
 278                  */
 279                 i8259A_chip.irq_mask_ack = disable_8259A_irq;
 280         else
 281                 i8259A_chip.irq_mask_ack = mask_and_ack_8259A;
 282
 283         udelay(100);            /* wait for 8259A to initialize */
 284
 285         outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */
 286         outb(cached_slave_mask, PIC_SLAVE_IMR);   /* restore slave IRQ mask */
 287
 288         raw_spin_unlock_irqrestore(&i8259A_lock, flags);
 289 }
 290
 291 /*
 292  * IRQ2 is cascade interrupt to second interrupt controller
 293  */
 294 static struct irqaction irq2 = {
 295         .handler = no_action,
 296         .name = "cascade",
 297         .flags = IRQF_NO_THREAD,
 298 };
 299
 300 static struct resource pic1_io_resource = {
 301         .name = "pic1",
 302         .start = PIC_MASTER_CMD,
 303         .end = PIC_MASTER_IMR,
 304         .flags = IORESOURCE_BUSY
 305 };
 306
 307 static struct resource pic2_io_resource = {
 308         .name = "pic2",
 309         .start = PIC_SLAVE_CMD,
 310         .end = PIC_SLAVE_IMR,
 311         .flags = IORESOURCE_BUSY
 312 };
 313
 314 static int i8259A_irq_domain_map(struct irq_domain *d, unsigned int virq,
 315                                  irq_hw_number_t hw)
 316 {
 317         irq_set_chip_and_handler(virq, &i8259A_chip, handle_level_irq);
 318         irq_set_probe(virq);
 319         return 0;
 320 }
 321
 322 static struct irq_domain_ops i8259A_ops = {
 323         .map = i8259A_irq_domain_map,
 324         .xlate = irq_domain_xlate_onecell,
 325 };
 326
 327 /*
 328  * On systems with i8259-style interrupt controllers we assume for
 329  * driver compatibility reasons interrupts 0 - 15 to be the i8259
 330  * interrupts even if the hardware uses a different interrupt numbering.
 331  */
 332 struct irq_domain * __init __init_i8259_irqs(struct device_node *node)
 333 {
 334         struct irq_domain *domain;
 335
 336         insert_resource(&ioport_resource, &pic1_io_resource);
 337         insert_resource(&ioport_resource, &pic2_io_resource);
 338
 339         init_8259A(0);
 340
 341         domain = irq_domain_add_legacy(node, 16, I8259A_IRQ_BASE, 0,
 342                                        &i8259A_ops, NULL);
 343         if (!domain)
 344                 panic("Failed to add i8259 IRQ domain");
 345
 346         setup_irq(I8259A_IRQ_BASE + PIC_CASCADE_IR, &irq2);
 347         return domain;
 348 }
 349
 350 void __init init_i8259_irqs(void)
 351 {
 352         __init_i8259_irqs(NULL);
 353 }
 354
 355 static void i8259_irq_dispatch(struct irq_desc *desc)
 356 {
 357         struct irq_domain *domain = irq_desc_get_handler_data(desc);
 358         int hwirq = i8259_irq();
 359         unsigned int irq;
 360
 361         if (hwirq < 0)
 362                 return;
 363
 364         irq = irq_linear_revmap(domain, hwirq);
 365         generic_handle_irq(irq);
 366 }
 367
 368 int __init i8259_of_init(struct device_node *node, struct device_node *parent)
 369 {
 370         struct irq_domain *domain;
 371         unsigned int parent_irq;
 372
 373         parent_irq = irq_of_parse_and_map(node, 0);
 374         if (!parent_irq) {
 375                 pr_err("Failed to map i8259 parent IRQ\n");
 376                 return -ENODEV;
 377         }
 378
 379         domain = __init_i8259_irqs(node);
 380         irq_set_chained_handler_and_data(parent_irq, i8259_irq_dispatch,
 381                                          domain);
 382         return 0;
 383 }
 384 IRQCHIP_DECLARE(i8259, "intel,i8259", i8259_of_init);