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 18#include <asm/io.h> 19 20void enable_8259A_irq(unsigned int irq); 21void disable_8259A_irq(unsigned int irq); 22 23/* 24 * This is the 'legacy' 8259A Programmable Interrupt Controller, 25 * present in the majority of PC/AT boxes. 26 * plus some generic x86 specific things if generic specifics makes 27 * any sense at all. 28 * this file should become arch/i386/kernel/irq.c when the old irq.c 29 * moves to arch independent land 30 */ 31 32static spinlock_t i8259A_lock = SPIN_LOCK_UNLOCKED; 33 34static void end_8259A_irq (unsigned int irq) 35{ 36 if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS))) 37 enable_8259A_irq(irq); 38} 39 40#define shutdown_8259A_irq disable_8259A_irq 41 42void mask_and_ack_8259A(unsigned int); 43 44static unsigned int startup_8259A_irq(unsigned int irq) 45{ 46 enable_8259A_irq(irq); 47 48 return 0; /* never anything pending */ 49} 50 51static struct hw_interrupt_type i8259A_irq_type = { 52 "XT-PIC", 53 startup_8259A_irq, 54 shutdown_8259A_irq, 55 enable_8259A_irq, 56 disable_8259A_irq, 57 mask_and_ack_8259A, 58 end_8259A_irq, 59 NULL 60}; 61 62/* 63 * 8259A PIC functions to handle ISA devices: 64 */ 65 66/* 67 * This contains the irq mask for both 8259A irq controllers, 68 */ 69static unsigned int cached_irq_mask = 0xffff; 70 71#define cached_21 (cached_irq_mask) 72#define cached_A1 (cached_irq_mask >> 8) 73 74void disable_8259A_irq(unsigned int irq) 75{ 76 unsigned int mask = 1 << irq; 77 unsigned long flags; 78 79 spin_lock_irqsave(&i8259A_lock, flags); 80 cached_irq_mask |= mask; 81 if (irq & 8) 82 outb(cached_A1,0xA1); 83 else 84 outb(cached_21,0x21); 85 spin_unlock_irqrestore(&i8259A_lock, flags); 86} 87 88void enable_8259A_irq(unsigned int irq) 89{ 90 unsigned int mask = ~(1 << irq); 91 unsigned long flags; 92 93 spin_lock_irqsave(&i8259A_lock, flags); 94 cached_irq_mask &= mask; 95 if (irq & 8) 96 outb(cached_A1,0xA1); 97 else 98 outb(cached_21,0x21); 99 spin_unlock_irqrestore(&i8259A_lock, flags); 100} 101 102int i8259A_irq_pending(unsigned int irq) 103{ 104 unsigned int mask = 1 << irq; 105 unsigned long flags; 106 int ret; 107 108 spin_lock_irqsave(&i8259A_lock, flags); 109 if (irq < 8) 110 ret = inb(0x20) & mask; 111 else 112 ret = inb(0xA0) & (mask >> 8); 113 spin_unlock_irqrestore(&i8259A_lock, flags); 114 115 return ret; 116} 117 118void make_8259A_irq(unsigned int irq) 119{ 120 disable_irq_nosync(irq); 121 irq_desc[irq].handler = &i8259A_irq_type; 122 enable_irq(irq); 123} 124 125/* 126 * This function assumes to be called rarely. Switching between 127 * 8259A registers is slow. 128 * This has to be protected by the irq controller spinlock 129 * before being called. 130 */ 131static inline int i8259A_irq_real(unsigned int irq) 132{ 133 int value; 134 int irqmask = 1 << irq; 135 136 if (irq < 8) { 137 outb(0x0B,0x20); /* ISR register */ 138 value = inb(0x20) & irqmask; 139 outb(0x0A,0x20); /* back to the IRR register */ 140 return value; 141 } 142 outb(0x0B,0xA0); /* ISR register */ 143 value = inb(0xA0) & (irqmask >> 8); 144 outb(0x0A,0xA0); /* back to the IRR register */ 145 return value; 146} 147 148/* 149 * Careful! The 8259A is a fragile beast, it pretty 150 * much _has_ to be done exactly like this (mask it 151 * first, _then_ send the EOI, and the order of EOI 152 * to the two 8259s is important! 153 */ 154void mask_and_ack_8259A(unsigned int irq) 155{ 156 unsigned int irqmask = 1 << irq; 157 unsigned long flags; 158 159 spin_lock_irqsave(&i8259A_lock, flags); 160 /* 161 * Lightweight spurious IRQ detection. We do not want to overdo 162 * spurious IRQ handling - it's usually a sign of hardware problems, so 163 * we only do the checks we can do without slowing down good hardware 164 * nnecesserily. 165 * 166 * Note that IRQ7 and IRQ15 (the two spurious IRQs usually resulting 167 * rom the 8259A-1|2 PICs) occur even if the IRQ is masked in the 8259A. 168 * Thus we can check spurious 8259A IRQs without doing the quite slow 169 * i8259A_irq_real() call for every IRQ. This does not cover 100% of 170 * spurious interrupts, but should be enough to warn the user that 171 * there is something bad going on ... 172 */ 173 if (cached_irq_mask & irqmask) 174 goto spurious_8259A_irq; 175 cached_irq_mask |= irqmask; 176 177handle_real_irq: 178 if (irq & 8) { 179 inb(0xA1); /* DUMMY - (do we need this?) */ 180 outb(cached_A1,0xA1); 181 outb(0x60+(irq&7),0xA0);/* 'Specific EOI' to slave */ 182 outb(0x62,0x20); /* 'Specific EOI' to master-IRQ2 */ 183 } else { 184 inb(0x21); /* DUMMY - (do we need this?) */ 185 outb(cached_21,0x21); 186 outb(0x60+irq,0x20); /* 'Specific EOI' to master */ 187 } 188 spin_unlock_irqrestore(&i8259A_lock, flags); 189 return; 190 191spurious_8259A_irq: 192 /* 193 * this is the slow path - should happen rarely. 194 */ 195 if (i8259A_irq_real(irq)) 196 /* 197 * oops, the IRQ _is_ in service according to the 198 * 8259A - not spurious, go handle it. 199 */ 200 goto handle_real_irq; 201 202 { 203 static int spurious_irq_mask = 0; 204 /* 205 * At this point we can be sure the IRQ is spurious, 206 * lets ACK and report it. [once per IRQ] 207 */ 208 if (!(spurious_irq_mask & irqmask)) { 209 printk("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 222void __init init_8259A(int auto_eoi) 223{ 224 unsigned long flags; 225 226 spin_lock_irqsave(&i8259A_lock, flags); 227 228 outb(0xff, 0x21); /* mask all of 8259A-1 */ 229 outb(0xff, 0xA1); /* mask all of 8259A-2 */ 230 231 /* 232 * outb_p - this has to work on a wide range of PC hardware. 233 */ 234 outb_p(0x11, 0x20); /* ICW1: select 8259A-1 init */ 235 outb_p(0x00, 0x21); /* ICW2: 8259A-1 IR0-7 mapped to 0x00-0x07 */ 236 outb_p(0x04, 0x21); /* 8259A-1 (the master) has a slave on IR2 */ 237 if (auto_eoi) 238 outb_p(0x03, 0x21); /* master does Auto EOI */ 239 else 240 outb_p(0x01, 0x21); /* master expects normal EOI */ 241 242 outb_p(0x11, 0xA0); /* ICW1: select 8259A-2 init */ 243 outb_p(0x08, 0xA1); /* ICW2: 8259A-2 IR0-7 mapped to 0x08-0x0f */ 244 outb_p(0x02, 0xA1); /* 8259A-2 is a slave on master's IR2 */ 245 outb_p(0x01, 0xA1); /* (slave's support for AEOI in flat mode 246 is to be investigated) */ 247 248 if (auto_eoi) 249 /* 250 * in AEOI mode we just have to mask the interrupt 251 * when acking. 252 */ 253 i8259A_irq_type.ack = disable_8259A_irq; 254 else 255 i8259A_irq_type.ack = mask_and_ack_8259A; 256 257 udelay(100); /* wait for 8259A to initialize */ 258 259 outb(cached_21, 0x21); /* restore master IRQ mask */ 260 outb(cached_A1, 0xA1); /* restore slave IRQ mask */ 261 262 spin_unlock_irqrestore(&i8259A_lock, flags); 263} 264 265asmlinkage void i8259_do_irq(int irq, struct pt_regs regs) 266{ 267 panic("i8259_do_irq: I want to be implemented"); 268} 269 270/* 271 * IRQ2 is cascade interrupt to second interrupt controller 272 */ 273static struct irqaction irq2 = { 274 no_action, 0, 0, "cascade", NULL, NULL 275}; 276 277static struct resource pic1_io_resource = { 278 "pic1", 0x20, 0x3f, IORESOURCE_BUSY 279}; 280 281static struct resource pic2_io_resource = { 282 "pic2", 0xa0, 0xbf, IORESOURCE_BUSY 283}; 284 285/* 286 * On systems with i8259-style interrupt controllers we assume for 287 * driver compatibility reasons interrupts 0 - 15 to be the i8295 288 * interrupts even if the hardware uses a different interrupt numbering. 289 */ 290void __init init_i8259_irqs (void) 291{ 292 int i; 293 294 request_resource(&ioport_resource, &pic1_io_resource); 295 request_resource(&ioport_resource, &pic2_io_resource); 296 297 init_8259A(0); 298 299 for (i = 0; i < 16; i++) { 300 irq_desc[i].status = IRQ_DISABLED; 301 irq_desc[i].action = 0; 302 irq_desc[i].depth = 1; 303 irq_desc[i].handler = &i8259A_irq_type; 304 } 305 306 setup_irq(2, &irq2); 307} 308