arch/mips/kernel/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/kernel.h>
  16 #include <linux/spinlock.h>
  17 #include <linux/sysdev.h>
  18
  19 #include <asm/i8259.h>
  20 #include <asm/io.h>
  21
  22 void enable_8259A_irq(unsigned int irq);
  23 void disable_8259A_irq(unsigned int irq);
  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  * this file should become arch/i386/kernel/irq.c when the old irq.c
  31  * moves to arch independent land
  32  */
  33
  34 DEFINE_SPINLOCK(i8259A_lock);
  35
  36 static void end_8259A_irq (unsigned int irq)
  37 {
  38         if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)) &&
  39             irq_desc[irq].action)
  40                 enable_8259A_irq(irq);
  41 }
  42
  43 #define shutdown_8259A_irq      disable_8259A_irq
  44
  45 void mask_and_ack_8259A(unsigned int);
  46
  47 static unsigned int startup_8259A_irq(unsigned int irq)
  48 {
  49         enable_8259A_irq(irq);
  50
  51         return 0; /* never anything pending */
  52 }
  53
  54 static struct hw_interrupt_type i8259A_irq_type = {
  55         .typename = "XT-PIC",
  56         .startup = startup_8259A_irq,
  57         .shutdown = shutdown_8259A_irq,
  58         .enable = enable_8259A_irq,
  59         .disable = disable_8259A_irq,
  60         .ack = mask_and_ack_8259A,
  61         .end = end_8259A_irq,
  62 };
  63
  64 /*
  65  * 8259A PIC functions to handle ISA devices:
  66  */
  67
  68 /*
  69  * This contains the irq mask for both 8259A irq controllers,
  70  */
  71 static unsigned int cached_irq_mask = 0xffff;
  72
  73 #define cached_21       (cached_irq_mask)
  74 #define cached_A1       (cached_irq_mask >> 8)
  75
  76 void disable_8259A_irq(unsigned int irq)
  77 {
  78         unsigned int mask = 1 << irq;
  79         unsigned long flags;
  80
  81         spin_lock_irqsave(&i8259A_lock, flags);
  82         cached_irq_mask |= mask;
  83         if (irq & 8)
  84                 outb(cached_A1,0xA1);
  85         else
  86                 outb(cached_21,0x21);
  87         spin_unlock_irqrestore(&i8259A_lock, flags);
  88 }
  89
  90 void enable_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_A1,0xA1);
  99         else
 100                 outb(cached_21,0x21);
 101         spin_unlock_irqrestore(&i8259A_lock, flags);
 102 }
 103
 104 int i8259A_irq_pending(unsigned int irq)
 105 {
 106         unsigned int mask = 1 << irq;
 107         unsigned long flags;
 108         int ret;
 109
 110         spin_lock_irqsave(&i8259A_lock, flags);
 111         if (irq < 8)
 112                 ret = inb(0x20) & mask;
 113         else
 114                 ret = inb(0xA0) & (mask >> 8);
 115         spin_unlock_irqrestore(&i8259A_lock, flags);
 116
 117         return ret;
 118 }
 119
 120 void make_8259A_irq(unsigned int irq)
 121 {
 122         disable_irq_nosync(irq);
 123         irq_desc[irq].handler = &i8259A_irq_type;
 124         enable_irq(irq);
 125 }
 126
 127 /*
 128  * This function assumes to be called rarely. Switching between
 129  * 8259A registers is slow.
 130  * This has to be protected by the irq controller spinlock
 131  * before being called.
 132  */
 133 static inline int i8259A_irq_real(unsigned int irq)
 134 {
 135         int value;
 136         int irqmask = 1 << irq;
 137
 138         if (irq < 8) {
 139                 outb(0x0B,0x20);                /* ISR register */
 140                 value = inb(0x20) & irqmask;
 141                 outb(0x0A,0x20);                /* back to the IRR register */
 142                 return value;
 143         }
 144         outb(0x0B,0xA0);                /* ISR register */
 145         value = inb(0xA0) & (irqmask >> 8);
 146         outb(0x0A,0xA0);                /* back to the IRR register */
 147         return value;
 148 }
 149
 150 /*
 151  * Careful! The 8259A is a fragile beast, it pretty
 152  * much _has_ to be done exactly like this (mask it
 153  * first, _then_ send the EOI, and the order of EOI
 154  * to the two 8259s is important!
 155  */
 156 void mask_and_ack_8259A(unsigned int irq)
 157 {
 158         unsigned int irqmask = 1 << irq;
 159         unsigned long flags;
 160
 161         spin_lock_irqsave(&i8259A_lock, flags);
 162         /*
 163          * Lightweight spurious IRQ detection. We do not want to overdo
 164          * spurious IRQ handling - it's usually a sign of hardware problems, so
 165          * we only do the checks we can do without slowing down good hardware
 166          * nnecesserily.
 167          *
 168          * Note that IRQ7 and IRQ15 (the two spurious IRQs usually resulting
 169          * rom the 8259A-1|2 PICs) occur even if the IRQ is masked in the 8259A.
 170          * Thus we can check spurious 8259A IRQs without doing the quite slow
 171          * i8259A_irq_real() call for every IRQ.  This does not cover 100% of
 172          * spurious interrupts, but should be enough to warn the user that
 173          * there is something bad going on ...
 174          */
 175         if (cached_irq_mask & irqmask)
 176                 goto spurious_8259A_irq;
 177         cached_irq_mask |= irqmask;
 178
 179 handle_real_irq:
 180         if (irq & 8) {
 181                 inb(0xA1);              /* DUMMY - (do we need this?) */
 182                 outb(cached_A1,0xA1);
 183                 outb(0x60+(irq&7),0xA0);/* 'Specific EOI' to slave */
 184                 outb(0x62,0x20);        /* 'Specific EOI' to master-IRQ2 */
 185         } else {
 186                 inb(0x21);              /* DUMMY - (do we need this?) */
 187                 outb(cached_21,0x21);
 188                 outb(0x60+irq,0x20);    /* 'Specific EOI' to master */
 189         }
 190 #ifdef CONFIG_MIPS_MT_SMTC
 191         if (irq_hwmask[irq] & ST0_IM)
 192                 set_c0_status(irq_hwmask[irq] & ST0_IM);
 193 #endif /* CONFIG_MIPS_MT_SMTC */
 194         spin_unlock_irqrestore(&i8259A_lock, flags);
 195         return;
 196
 197 spurious_8259A_irq:
 198         /*
 199          * this is the slow path - should happen rarely.
 200          */
 201         if (i8259A_irq_real(irq))
 202                 /*
 203                  * oops, the IRQ _is_ in service according to the
 204                  * 8259A - not spurious, go handle it.
 205                  */
 206                 goto handle_real_irq;
 207
 208         {
 209                 static int spurious_irq_mask = 0;
 210                 /*
 211                  * At this point we can be sure the IRQ is spurious,
 212                  * lets ACK and report it. [once per IRQ]
 213                  */
 214                 if (!(spurious_irq_mask & irqmask)) {
 215                         printk(KERN_DEBUG "spurious 8259A interrupt: IRQ%d.\n", irq);
 216                         spurious_irq_mask |= irqmask;
 217                 }
 218                 atomic_inc(&irq_err_count);
 219                 /*
 220                  * Theoretically we do not have to handle this IRQ,
 221                  * but in Linux this does not cause problems and is
 222                  * simpler for us.
 223                  */
 224                 goto handle_real_irq;
 225         }
 226 }
 227
 228 static int i8259A_resume(struct sys_device *dev)
 229 {
 230         init_8259A(0);
 231         return 0;
 232 }
 233
 234 static struct sysdev_class i8259_sysdev_class = {
 235         set_kset_name("i8259"),
 236         .resume = i8259A_resume,
 237 };
 238
 239 static struct sys_device device_i8259A = {
 240         .id     = 0,
 241         .cls    = &i8259_sysdev_class,
 242 };
 243
 244 static int __init i8259A_init_sysfs(void)
 245 {
 246         int error = sysdev_class_register(&i8259_sysdev_class);
 247         if (!error)
 248                 error = sysdev_register(&device_i8259A);
 249         return error;
 250 }
 251
 252 device_initcall(i8259A_init_sysfs);
 253
 254 void __init init_8259A(int auto_eoi)
 255 {
 256         unsigned long flags;
 257
 258         spin_lock_irqsave(&i8259A_lock, flags);
 259
 260         outb(0xff, 0x21);       /* mask all of 8259A-1 */
 261         outb(0xff, 0xA1);       /* mask all of 8259A-2 */
 262
 263         /*
 264          * outb_p - this has to work on a wide range of PC hardware.
 265          */
 266         outb_p(0x11, 0x20);     /* ICW1: select 8259A-1 init */
 267         outb_p(0x00, 0x21);     /* ICW2: 8259A-1 IR0-7 mapped to 0x00-0x07 */
 268         outb_p(0x04, 0x21);     /* 8259A-1 (the master) has a slave on IR2 */
 269         if (auto_eoi)
 270                 outb_p(0x03, 0x21);     /* master does Auto EOI */
 271         else
 272                 outb_p(0x01, 0x21);     /* master expects normal EOI */
 273
 274         outb_p(0x11, 0xA0);     /* ICW1: select 8259A-2 init */
 275         outb_p(0x08, 0xA1);     /* ICW2: 8259A-2 IR0-7 mapped to 0x08-0x0f */
 276         outb_p(0x02, 0xA1);     /* 8259A-2 is a slave on master's IR2 */
 277         outb_p(0x01, 0xA1);     /* (slave's support for AEOI in flat mode
 278                                     is to be investigated) */
 279
 280         if (auto_eoi)
 281                 /*
 282                  * in AEOI mode we just have to mask the interrupt
 283                  * when acking.
 284                  */
 285                 i8259A_irq_type.ack = disable_8259A_irq;
 286         else
 287                 i8259A_irq_type.ack = mask_and_ack_8259A;
 288
 289         udelay(100);            /* wait for 8259A to initialize */
 290
 291         outb(cached_21, 0x21);  /* restore master IRQ mask */
 292         outb(cached_A1, 0xA1);  /* restore slave IRQ mask */
 293
 294         spin_unlock_irqrestore(&i8259A_lock, flags);
 295 }
 296
 297 /*
 298  * IRQ2 is cascade interrupt to second interrupt controller
 299  */
 300 static struct irqaction irq2 = {
 301         no_action, 0, CPU_MASK_NONE, "cascade", NULL, NULL
 302 };
 303
 304 static struct resource pic1_io_resource = {
 305         "pic1", 0x20, 0x3f, IORESOURCE_BUSY
 306 };
 307
 308 static struct resource pic2_io_resource = {
 309         "pic2", 0xa0, 0xbf, IORESOURCE_BUSY
 310 };
 311
 312 /*
 313  * On systems with i8259-style interrupt controllers we assume for
 314  * driver compatibility reasons interrupts 0 - 15 to be the i8259
 315  * interrupts even if the hardware uses a different interrupt numbering.
 316  */
 317 void __init init_i8259_irqs (void)
 318 {
 319         int i;
 320
 321         request_resource(&ioport_resource, &pic1_io_resource);
 322         request_resource(&ioport_resource, &pic2_io_resource);
 323
 324         init_8259A(0);
 325
 326         for (i = 0; i < 16; i++) {
 327                 irq_desc[i].status = IRQ_DISABLED;
 328                 irq_desc[i].action = NULL;
 329                 irq_desc[i].depth = 1;
 330                 irq_desc[i].handler = &i8259A_irq_type;
 331         }
 332
 333         setup_irq(2, &irq2);
 334 }