1 /* 2 * linux/kernel/irq/handle.c 3 * 4 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar 5 * Copyright (C) 2005-2006, Thomas Gleixner, Russell King 6 * 7 * This file contains the core interrupt handling code. 8 * 9 * Detailed information is available in Documentation/DocBook/genericirq 10 * 11 */ 12 13 #include <linux/irq.h> 14 #include <linux/module.h> 15 #include <linux/random.h> 16 #include <linux/interrupt.h> 17 #include <linux/kernel_stat.h> 18 19 #include "internals.h" 20 21 /** 22 * handle_bad_irq - handle spurious and unhandled irqs 23 */ 24 void fastcall 25 handle_bad_irq(unsigned int irq, struct irq_desc *desc, struct pt_regs *regs) 26 { 27 print_irq_desc(irq, desc); 28 kstat_this_cpu.irqs[irq]++; 29 ack_bad_irq(irq); 30 } 31 32 /* 33 * Linux has a controller-independent interrupt architecture. 34 * Every controller has a 'controller-template', that is used 35 * by the main code to do the right thing. Each driver-visible 36 * interrupt source is transparently wired to the appropriate 37 * controller. Thus drivers need not be aware of the 38 * interrupt-controller. 39 * 40 * The code is designed to be easily extended with new/different 41 * interrupt controllers, without having to do assembly magic or 42 * having to touch the generic code. 43 * 44 * Controller mappings for all interrupt sources: 45 */ 46 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned = { 47 [0 ... NR_IRQS-1] = { 48 .status = IRQ_DISABLED, 49 .chip = &no_irq_chip, 50 .handle_irq = handle_bad_irq, 51 .depth = 1, 52 .lock = SPIN_LOCK_UNLOCKED, 53 #ifdef CONFIG_SMP 54 .affinity = CPU_MASK_ALL 55 #endif 56 } 57 }; 58 59 /* 60 * What should we do if we get a hw irq event on an illegal vector? 61 * Each architecture has to answer this themself. 62 */ 63 static void ack_bad(unsigned int irq) 64 { 65 print_irq_desc(irq, irq_desc + irq); 66 ack_bad_irq(irq); 67 } 68 69 /* 70 * NOP functions 71 */ 72 static void noop(unsigned int irq) 73 { 74 } 75 76 static unsigned int noop_ret(unsigned int irq) 77 { 78 return 0; 79 } 80 81 /* 82 * Generic no controller implementation 83 */ 84 struct irq_chip no_irq_chip = { 85 .name = "none", 86 .startup = noop_ret, 87 .shutdown = noop, 88 .enable = noop, 89 .disable = noop, 90 .ack = ack_bad, 91 .end = noop, 92 }; 93 94 /* 95 * Generic dummy implementation which can be used for 96 * real dumb interrupt sources 97 */ 98 struct irq_chip dummy_irq_chip = { 99 .name = "dummy", 100 .startup = noop_ret, 101 .shutdown = noop, 102 .enable = noop, 103 .disable = noop, 104 .ack = noop, 105 .mask = noop, 106 .unmask = noop, 107 .end = noop, 108 }; 109 110 /* 111 * Special, empty irq handler: 112 */ 113 irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs) 114 { 115 return IRQ_NONE; 116 } 117 118 /** 119 * handle_IRQ_event - irq action chain handler 120 * @irq: the interrupt number 121 * @regs: pointer to a register structure 122 * @action: the interrupt action chain for this irq 123 * 124 * Handles the action chain of an irq event 125 */ 126 irqreturn_t handle_IRQ_event(unsigned int irq, struct pt_regs *regs, 127 struct irqaction *action) 128 { 129 irqreturn_t ret, retval = IRQ_NONE; 130 unsigned int status = 0; 131 132 handle_dynamic_tick(action); 133 134 if (!(action->flags & IRQF_DISABLED)) 135 local_irq_enable_in_hardirq(); 136 137 do { 138 ret = action->handler(irq, action->dev_id, regs); 139 if (ret == IRQ_HANDLED) 140 status |= action->flags; 141 retval |= ret; 142 action = action->next; 143 } while (action); 144 145 if (status & IRQF_SAMPLE_RANDOM) 146 add_interrupt_randomness(irq); 147 local_irq_disable(); 148 149 return retval; 150 } 151 152 /** 153 * __do_IRQ - original all in one highlevel IRQ handler 154 * @irq: the interrupt number 155 * @regs: pointer to a register structure 156 * 157 * __do_IRQ handles all normal device IRQ's (the special 158 * SMP cross-CPU interrupts have their own specific 159 * handlers). 160 * 161 * This is the original x86 implementation which is used for every 162 * interrupt type. 163 */ 164 fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs) 165 { 166 struct irq_desc *desc = irq_desc + irq; 167 struct irqaction *action; 168 unsigned int status; 169 170 kstat_this_cpu.irqs[irq]++; 171 if (CHECK_IRQ_PER_CPU(desc->status)) { 172 irqreturn_t action_ret; 173 174 /* 175 * No locking required for CPU-local interrupts: 176 */ 177 if (desc->chip->ack) 178 desc->chip->ack(irq); 179 action_ret = handle_IRQ_event(irq, regs, desc->action); 180 desc->chip->end(irq); 181 return 1; 182 } 183 184 spin_lock(&desc->lock); 185 if (desc->chip->ack) 186 desc->chip->ack(irq); 187 /* 188 * REPLAY is when Linux resends an IRQ that was dropped earlier 189 * WAITING is used by probe to mark irqs that are being tested 190 */ 191 status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING); 192 status |= IRQ_PENDING; /* we _want_ to handle it */ 193 194 /* 195 * If the IRQ is disabled for whatever reason, we cannot 196 * use the action we have. 197 */ 198 action = NULL; 199 if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) { 200 action = desc->action; 201 status &= ~IRQ_PENDING; /* we commit to handling */ 202 status |= IRQ_INPROGRESS; /* we are handling it */ 203 } 204 desc->status = status; 205 206 /* 207 * If there is no IRQ handler or it was disabled, exit early. 208 * Since we set PENDING, if another processor is handling 209 * a different instance of this same irq, the other processor 210 * will take care of it. 211 */ 212 if (unlikely(!action)) 213 goto out; 214 215 /* 216 * Edge triggered interrupts need to remember 217 * pending events. 218 * This applies to any hw interrupts that allow a second 219 * instance of the same irq to arrive while we are in do_IRQ 220 * or in the handler. But the code here only handles the _second_ 221 * instance of the irq, not the third or fourth. So it is mostly 222 * useful for irq hardware that does not mask cleanly in an 223 * SMP environment. 224 */ 225 for (;;) { 226 irqreturn_t action_ret; 227 228 spin_unlock(&desc->lock); 229 230 action_ret = handle_IRQ_event(irq, regs, action); 231 232 spin_lock(&desc->lock); 233 if (!noirqdebug) 234 note_interrupt(irq, desc, action_ret, regs); 235 if (likely(!(desc->status & IRQ_PENDING))) 236 break; 237 desc->status &= ~IRQ_PENDING; 238 } 239 desc->status &= ~IRQ_INPROGRESS; 240 241 out: 242 /* 243 * The ->end() handler has to deal with interrupts which got 244 * disabled while the handler was running. 245 */ 246 desc->chip->end(irq); 247 spin_unlock(&desc->lock); 248 249 return 1; 250 } 251 252 #ifdef CONFIG_TRACE_IRQFLAGS 253 254 /* 255 * lockdep: we want to handle all irq_desc locks as a single lock-class: 256 */ 257 static struct lock_class_key irq_desc_lock_class; 258 259 void early_init_irq_lock_class(void) 260 { 261 int i; 262 263 for (i = 0; i < NR_IRQS; i++) 264 lockdep_set_class(&irq_desc[i].lock, &irq_desc_lock_class); 265 } 266 267 #endif 268