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