1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/linkage.h> 3 #include <linux/errno.h> 4 #include <linux/signal.h> 5 #include <linux/sched.h> 6 #include <linux/ioport.h> 7 #include <linux/interrupt.h> 8 #include <linux/irq.h> 9 #include <linux/timex.h> 10 #include <linux/random.h> 11 #include <linux/init.h> 12 #include <linux/kernel_stat.h> 13 #include <linux/syscore_ops.h> 14 #include <linux/bitops.h> 15 #include <linux/acpi.h> 16 #include <linux/io.h> 17 #include <linux/delay.h> 18 19 #include <linux/atomic.h> 20 #include <asm/timer.h> 21 #include <asm/hw_irq.h> 22 #include <asm/pgtable.h> 23 #include <asm/desc.h> 24 #include <asm/apic.h> 25 #include <asm/i8259.h> 26 27 /* 28 * This is the 'legacy' 8259A Programmable Interrupt Controller, 29 * present in the majority of PC/AT boxes. 30 * plus some generic x86 specific things if generic specifics makes 31 * any sense at all. 32 */ 33 static void init_8259A(int auto_eoi); 34 35 static int i8259A_auto_eoi; 36 DEFINE_RAW_SPINLOCK(i8259A_lock); 37 38 /* 39 * 8259A PIC functions to handle ISA devices: 40 */ 41 42 /* 43 * This contains the irq mask for both 8259A irq controllers, 44 */ 45 unsigned int cached_irq_mask = 0xffff; 46 47 /* 48 * Not all IRQs can be routed through the IO-APIC, eg. on certain (older) 49 * boards the timer interrupt is not really connected to any IO-APIC pin, 50 * it's fed to the master 8259A's IR0 line only. 51 * 52 * Any '1' bit in this mask means the IRQ is routed through the IO-APIC. 53 * this 'mixed mode' IRQ handling costs nothing because it's only used 54 * at IRQ setup time. 55 */ 56 unsigned long io_apic_irqs; 57 58 static void mask_8259A_irq(unsigned int irq) 59 { 60 unsigned int mask = 1 << irq; 61 unsigned long flags; 62 63 raw_spin_lock_irqsave(&i8259A_lock, flags); 64 cached_irq_mask |= mask; 65 if (irq & 8) 66 outb(cached_slave_mask, PIC_SLAVE_IMR); 67 else 68 outb(cached_master_mask, PIC_MASTER_IMR); 69 raw_spin_unlock_irqrestore(&i8259A_lock, flags); 70 } 71 72 static void disable_8259A_irq(struct irq_data *data) 73 { 74 mask_8259A_irq(data->irq); 75 } 76 77 static void unmask_8259A_irq(unsigned int irq) 78 { 79 unsigned int mask = ~(1 << irq); 80 unsigned long flags; 81 82 raw_spin_lock_irqsave(&i8259A_lock, flags); 83 cached_irq_mask &= mask; 84 if (irq & 8) 85 outb(cached_slave_mask, PIC_SLAVE_IMR); 86 else 87 outb(cached_master_mask, PIC_MASTER_IMR); 88 raw_spin_unlock_irqrestore(&i8259A_lock, flags); 89 } 90 91 static void enable_8259A_irq(struct irq_data *data) 92 { 93 unmask_8259A_irq(data->irq); 94 } 95 96 static int i8259A_irq_pending(unsigned int irq) 97 { 98 unsigned int mask = 1<<irq; 99 unsigned long flags; 100 int ret; 101 102 raw_spin_lock_irqsave(&i8259A_lock, flags); 103 if (irq < 8) 104 ret = inb(PIC_MASTER_CMD) & mask; 105 else 106 ret = inb(PIC_SLAVE_CMD) & (mask >> 8); 107 raw_spin_unlock_irqrestore(&i8259A_lock, flags); 108 109 return ret; 110 } 111 112 static void make_8259A_irq(unsigned int irq) 113 { 114 disable_irq_nosync(irq); 115 io_apic_irqs &= ~(1<<irq); 116 irq_set_chip_and_handler(irq, &i8259A_chip, handle_level_irq); 117 enable_irq(irq); 118 lapic_assign_legacy_vector(irq, true); 119 } 120 121 /* 122 * This function assumes to be called rarely. Switching between 123 * 8259A registers is slow. 124 * This has to be protected by the irq controller spinlock 125 * before being called. 126 */ 127 static inline int i8259A_irq_real(unsigned int irq) 128 { 129 int value; 130 int irqmask = 1<<irq; 131 132 if (irq < 8) { 133 outb(0x0B, PIC_MASTER_CMD); /* ISR register */ 134 value = inb(PIC_MASTER_CMD) & irqmask; 135 outb(0x0A, PIC_MASTER_CMD); /* back to the IRR register */ 136 return value; 137 } 138 outb(0x0B, PIC_SLAVE_CMD); /* ISR register */ 139 value = inb(PIC_SLAVE_CMD) & (irqmask >> 8); 140 outb(0x0A, PIC_SLAVE_CMD); /* back to the IRR register */ 141 return value; 142 } 143 144 /* 145 * Careful! The 8259A is a fragile beast, it pretty 146 * much _has_ to be done exactly like this (mask it 147 * first, _then_ send the EOI, and the order of EOI 148 * to the two 8259s is important! 149 */ 150 static void mask_and_ack_8259A(struct irq_data *data) 151 { 152 unsigned int irq = data->irq; 153 unsigned int irqmask = 1 << irq; 154 unsigned long flags; 155 156 raw_spin_lock_irqsave(&i8259A_lock, flags); 157 /* 158 * Lightweight spurious IRQ detection. We do not want 159 * to overdo spurious IRQ handling - it's usually a sign 160 * of hardware problems, so we only do the checks we can 161 * do without slowing down good hardware unnecessarily. 162 * 163 * Note that IRQ7 and IRQ15 (the two spurious IRQs 164 * usually resulting from the 8259A-1|2 PICs) occur 165 * even if the IRQ is masked in the 8259A. Thus we 166 * can check spurious 8259A IRQs without doing the 167 * quite slow i8259A_irq_real() call for every IRQ. 168 * This does not cover 100% of spurious interrupts, 169 * but should be enough to warn the user that there 170 * is something bad going on ... 171 */ 172 if (cached_irq_mask & irqmask) 173 goto spurious_8259A_irq; 174 cached_irq_mask |= irqmask; 175 176 handle_real_irq: 177 if (irq & 8) { 178 inb(PIC_SLAVE_IMR); /* DUMMY - (do we need this?) */ 179 outb(cached_slave_mask, PIC_SLAVE_IMR); 180 /* 'Specific EOI' to slave */ 181 outb(0x60+(irq&7), PIC_SLAVE_CMD); 182 /* 'Specific EOI' to master-IRQ2 */ 183 outb(0x60+PIC_CASCADE_IR, PIC_MASTER_CMD); 184 } else { 185 inb(PIC_MASTER_IMR); /* DUMMY - (do we need this?) */ 186 outb(cached_master_mask, PIC_MASTER_IMR); 187 outb(0x60+irq, PIC_MASTER_CMD); /* 'Specific EOI to master */ 188 } 189 raw_spin_unlock_irqrestore(&i8259A_lock, flags); 190 return; 191 192 spurious_8259A_irq: 193 /* 194 * this is the slow path - should happen rarely. 195 */ 196 if (i8259A_irq_real(irq)) 197 /* 198 * oops, the IRQ _is_ in service according to the 199 * 8259A - not spurious, go handle it. 200 */ 201 goto handle_real_irq; 202 203 { 204 static int spurious_irq_mask; 205 /* 206 * At this point we can be sure the IRQ is spurious, 207 * lets ACK and report it. [once per IRQ] 208 */ 209 if (!(spurious_irq_mask & irqmask)) { 210 printk(KERN_DEBUG 211 "spurious 8259A interrupt: IRQ%d.\n", irq); 212 spurious_irq_mask |= irqmask; 213 } 214 atomic_inc(&irq_err_count); 215 /* 216 * Theoretically we do not have to handle this IRQ, 217 * but in Linux this does not cause problems and is 218 * simpler for us. 219 */ 220 goto handle_real_irq; 221 } 222 } 223 224 struct irq_chip i8259A_chip = { 225 .name = "XT-PIC", 226 .irq_mask = disable_8259A_irq, 227 .irq_disable = disable_8259A_irq, 228 .irq_unmask = enable_8259A_irq, 229 .irq_mask_ack = mask_and_ack_8259A, 230 }; 231 232 static char irq_trigger[2]; 233 /** 234 * ELCR registers (0x4d0, 0x4d1) control edge/level of IRQ 235 */ 236 static void restore_ELCR(char *trigger) 237 { 238 outb(trigger[0], 0x4d0); 239 outb(trigger[1], 0x4d1); 240 } 241 242 static void save_ELCR(char *trigger) 243 { 244 /* IRQ 0,1,2,8,13 are marked as reserved */ 245 trigger[0] = inb(0x4d0) & 0xF8; 246 trigger[1] = inb(0x4d1) & 0xDE; 247 } 248 249 static void i8259A_resume(void) 250 { 251 init_8259A(i8259A_auto_eoi); 252 restore_ELCR(irq_trigger); 253 } 254 255 static int i8259A_suspend(void) 256 { 257 save_ELCR(irq_trigger); 258 return 0; 259 } 260 261 static void i8259A_shutdown(void) 262 { 263 /* Put the i8259A into a quiescent state that 264 * the kernel initialization code can get it 265 * out of. 266 */ 267 outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */ 268 outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */ 269 } 270 271 static struct syscore_ops i8259_syscore_ops = { 272 .suspend = i8259A_suspend, 273 .resume = i8259A_resume, 274 .shutdown = i8259A_shutdown, 275 }; 276 277 static void mask_8259A(void) 278 { 279 unsigned long flags; 280 281 raw_spin_lock_irqsave(&i8259A_lock, flags); 282 283 outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */ 284 outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */ 285 286 raw_spin_unlock_irqrestore(&i8259A_lock, flags); 287 } 288 289 static void unmask_8259A(void) 290 { 291 unsigned long flags; 292 293 raw_spin_lock_irqsave(&i8259A_lock, flags); 294 295 outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */ 296 outb(cached_slave_mask, PIC_SLAVE_IMR); /* restore slave IRQ mask */ 297 298 raw_spin_unlock_irqrestore(&i8259A_lock, flags); 299 } 300 301 static int probe_8259A(void) 302 { 303 unsigned long flags; 304 unsigned char probe_val = ~(1 << PIC_CASCADE_IR); 305 unsigned char new_val; 306 /* 307 * Check to see if we have a PIC. 308 * Mask all except the cascade and read 309 * back the value we just wrote. If we don't 310 * have a PIC, we will read 0xff as opposed to the 311 * value we wrote. 312 */ 313 raw_spin_lock_irqsave(&i8259A_lock, flags); 314 315 outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */ 316 outb(probe_val, PIC_MASTER_IMR); 317 new_val = inb(PIC_MASTER_IMR); 318 if (new_val != probe_val) { 319 printk(KERN_INFO "Using NULL legacy PIC\n"); 320 legacy_pic = &null_legacy_pic; 321 } 322 323 raw_spin_unlock_irqrestore(&i8259A_lock, flags); 324 return nr_legacy_irqs(); 325 } 326 327 static void init_8259A(int auto_eoi) 328 { 329 unsigned long flags; 330 331 i8259A_auto_eoi = auto_eoi; 332 333 raw_spin_lock_irqsave(&i8259A_lock, flags); 334 335 outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */ 336 337 /* 338 * outb_pic - this has to work on a wide range of PC hardware. 339 */ 340 outb_pic(0x11, PIC_MASTER_CMD); /* ICW1: select 8259A-1 init */ 341 342 /* ICW2: 8259A-1 IR0-7 mapped to ISA_IRQ_VECTOR(0) */ 343 outb_pic(ISA_IRQ_VECTOR(0), PIC_MASTER_IMR); 344 345 /* 8259A-1 (the master) has a slave on IR2 */ 346 outb_pic(1U << PIC_CASCADE_IR, PIC_MASTER_IMR); 347 348 if (auto_eoi) /* master does Auto EOI */ 349 outb_pic(MASTER_ICW4_DEFAULT | PIC_ICW4_AEOI, PIC_MASTER_IMR); 350 else /* master expects normal EOI */ 351 outb_pic(MASTER_ICW4_DEFAULT, PIC_MASTER_IMR); 352 353 outb_pic(0x11, PIC_SLAVE_CMD); /* ICW1: select 8259A-2 init */ 354 355 /* ICW2: 8259A-2 IR0-7 mapped to ISA_IRQ_VECTOR(8) */ 356 outb_pic(ISA_IRQ_VECTOR(8), PIC_SLAVE_IMR); 357 /* 8259A-2 is a slave on master's IR2 */ 358 outb_pic(PIC_CASCADE_IR, PIC_SLAVE_IMR); 359 /* (slave's support for AEOI in flat mode is to be investigated) */ 360 outb_pic(SLAVE_ICW4_DEFAULT, PIC_SLAVE_IMR); 361 362 if (auto_eoi) 363 /* 364 * In AEOI mode we just have to mask the interrupt 365 * when acking. 366 */ 367 i8259A_chip.irq_mask_ack = disable_8259A_irq; 368 else 369 i8259A_chip.irq_mask_ack = mask_and_ack_8259A; 370 371 udelay(100); /* wait for 8259A to initialize */ 372 373 outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */ 374 outb(cached_slave_mask, PIC_SLAVE_IMR); /* restore slave IRQ mask */ 375 376 raw_spin_unlock_irqrestore(&i8259A_lock, flags); 377 } 378 379 /* 380 * make i8259 a driver so that we can select pic functions at run time. the goal 381 * is to make x86 binary compatible among pc compatible and non-pc compatible 382 * platforms, such as x86 MID. 383 */ 384 385 static void legacy_pic_noop(void) { }; 386 static void legacy_pic_uint_noop(unsigned int unused) { }; 387 static void legacy_pic_int_noop(int unused) { }; 388 static int legacy_pic_irq_pending_noop(unsigned int irq) 389 { 390 return 0; 391 } 392 static int legacy_pic_probe(void) 393 { 394 return 0; 395 } 396 397 struct legacy_pic null_legacy_pic = { 398 .nr_legacy_irqs = 0, 399 .chip = &dummy_irq_chip, 400 .mask = legacy_pic_uint_noop, 401 .unmask = legacy_pic_uint_noop, 402 .mask_all = legacy_pic_noop, 403 .restore_mask = legacy_pic_noop, 404 .init = legacy_pic_int_noop, 405 .probe = legacy_pic_probe, 406 .irq_pending = legacy_pic_irq_pending_noop, 407 .make_irq = legacy_pic_uint_noop, 408 }; 409 410 struct legacy_pic default_legacy_pic = { 411 .nr_legacy_irqs = NR_IRQS_LEGACY, 412 .chip = &i8259A_chip, 413 .mask = mask_8259A_irq, 414 .unmask = unmask_8259A_irq, 415 .mask_all = mask_8259A, 416 .restore_mask = unmask_8259A, 417 .init = init_8259A, 418 .probe = probe_8259A, 419 .irq_pending = i8259A_irq_pending, 420 .make_irq = make_8259A_irq, 421 }; 422 423 struct legacy_pic *legacy_pic = &default_legacy_pic; 424 EXPORT_SYMBOL(legacy_pic); 425 426 static int __init i8259A_init_ops(void) 427 { 428 if (legacy_pic == &default_legacy_pic) 429 register_syscore_ops(&i8259_syscore_ops); 430 431 return 0; 432 } 433 434 device_initcall(i8259A_init_ops); 435