xref: /openbmc/linux/kernel/irq/manage.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  * linux/kernel/irq/manage.c
3  *
4  * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
5  *
6  * This file contains driver APIs to the irq subsystem.
7  */
8 
9 #include <linux/config.h>
10 #include <linux/irq.h>
11 #include <linux/module.h>
12 #include <linux/random.h>
13 #include <linux/interrupt.h>
14 
15 #include "internals.h"
16 
17 #ifdef CONFIG_SMP
18 
19 cpumask_t irq_affinity[NR_IRQS] = { [0 ... NR_IRQS-1] = CPU_MASK_ALL };
20 
21 #if defined (CONFIG_GENERIC_PENDING_IRQ) || defined (CONFIG_IRQBALANCE)
22 cpumask_t __cacheline_aligned pending_irq_cpumask[NR_IRQS];
23 #endif
24 
25 /**
26  *	synchronize_irq - wait for pending IRQ handlers (on other CPUs)
27  *
28  *	This function waits for any pending IRQ handlers for this interrupt
29  *	to complete before returning. If you use this function while
30  *	holding a resource the IRQ handler may need you will deadlock.
31  *
32  *	This function may be called - with care - from IRQ context.
33  */
34 void synchronize_irq(unsigned int irq)
35 {
36 	struct irq_desc *desc = irq_desc + irq;
37 
38 	while (desc->status & IRQ_INPROGRESS)
39 		cpu_relax();
40 }
41 
42 EXPORT_SYMBOL(synchronize_irq);
43 
44 #endif
45 
46 /**
47  *	disable_irq_nosync - disable an irq without waiting
48  *	@irq: Interrupt to disable
49  *
50  *	Disable the selected interrupt line.  Disables and Enables are
51  *	nested.
52  *	Unlike disable_irq(), this function does not ensure existing
53  *	instances of the IRQ handler have completed before returning.
54  *
55  *	This function may be called from IRQ context.
56  */
57 void disable_irq_nosync(unsigned int irq)
58 {
59 	irq_desc_t *desc = irq_desc + irq;
60 	unsigned long flags;
61 
62 	spin_lock_irqsave(&desc->lock, flags);
63 	if (!desc->depth++) {
64 		desc->status |= IRQ_DISABLED;
65 		desc->handler->disable(irq);
66 	}
67 	spin_unlock_irqrestore(&desc->lock, flags);
68 }
69 
70 EXPORT_SYMBOL(disable_irq_nosync);
71 
72 /**
73  *	disable_irq - disable an irq and wait for completion
74  *	@irq: Interrupt to disable
75  *
76  *	Disable the selected interrupt line.  Enables and Disables are
77  *	nested.
78  *	This function waits for any pending IRQ handlers for this interrupt
79  *	to complete before returning. If you use this function while
80  *	holding a resource the IRQ handler may need you will deadlock.
81  *
82  *	This function may be called - with care - from IRQ context.
83  */
84 void disable_irq(unsigned int irq)
85 {
86 	irq_desc_t *desc = irq_desc + irq;
87 
88 	disable_irq_nosync(irq);
89 	if (desc->action)
90 		synchronize_irq(irq);
91 }
92 
93 EXPORT_SYMBOL(disable_irq);
94 
95 /**
96  *	enable_irq - enable handling of an irq
97  *	@irq: Interrupt to enable
98  *
99  *	Undoes the effect of one call to disable_irq().  If this
100  *	matches the last disable, processing of interrupts on this
101  *	IRQ line is re-enabled.
102  *
103  *	This function may be called from IRQ context.
104  */
105 void enable_irq(unsigned int irq)
106 {
107 	irq_desc_t *desc = irq_desc + irq;
108 	unsigned long flags;
109 
110 	spin_lock_irqsave(&desc->lock, flags);
111 	switch (desc->depth) {
112 	case 0:
113 		WARN_ON(1);
114 		break;
115 	case 1: {
116 		unsigned int status = desc->status & ~IRQ_DISABLED;
117 
118 		desc->status = status;
119 		if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
120 			desc->status = status | IRQ_REPLAY;
121 			hw_resend_irq(desc->handler,irq);
122 		}
123 		desc->handler->enable(irq);
124 		/* fall-through */
125 	}
126 	default:
127 		desc->depth--;
128 	}
129 	spin_unlock_irqrestore(&desc->lock, flags);
130 }
131 
132 EXPORT_SYMBOL(enable_irq);
133 
134 /*
135  * Internal function that tells the architecture code whether a
136  * particular irq has been exclusively allocated or is available
137  * for driver use.
138  */
139 int can_request_irq(unsigned int irq, unsigned long irqflags)
140 {
141 	struct irqaction *action;
142 
143 	if (irq >= NR_IRQS)
144 		return 0;
145 
146 	action = irq_desc[irq].action;
147 	if (action)
148 		if (irqflags & action->flags & SA_SHIRQ)
149 			action = NULL;
150 
151 	return !action;
152 }
153 
154 /*
155  * Internal function to register an irqaction - typically used to
156  * allocate special interrupts that are part of the architecture.
157  */
158 int setup_irq(unsigned int irq, struct irqaction * new)
159 {
160 	struct irq_desc *desc = irq_desc + irq;
161 	struct irqaction *old, **p;
162 	unsigned long flags;
163 	int shared = 0;
164 
165 	if (desc->handler == &no_irq_type)
166 		return -ENOSYS;
167 	/*
168 	 * Some drivers like serial.c use request_irq() heavily,
169 	 * so we have to be careful not to interfere with a
170 	 * running system.
171 	 */
172 	if (new->flags & SA_SAMPLE_RANDOM) {
173 		/*
174 		 * This function might sleep, we want to call it first,
175 		 * outside of the atomic block.
176 		 * Yes, this might clear the entropy pool if the wrong
177 		 * driver is attempted to be loaded, without actually
178 		 * installing a new handler, but is this really a problem,
179 		 * only the sysadmin is able to do this.
180 		 */
181 		rand_initialize_irq(irq);
182 	}
183 
184 	/*
185 	 * The following block of code has to be executed atomically
186 	 */
187 	spin_lock_irqsave(&desc->lock,flags);
188 	p = &desc->action;
189 	if ((old = *p) != NULL) {
190 		/* Can't share interrupts unless both agree to */
191 		if (!(old->flags & new->flags & SA_SHIRQ)) {
192 			spin_unlock_irqrestore(&desc->lock,flags);
193 			return -EBUSY;
194 		}
195 
196 		/* add new interrupt at end of irq queue */
197 		do {
198 			p = &old->next;
199 			old = *p;
200 		} while (old);
201 		shared = 1;
202 	}
203 
204 	*p = new;
205 
206 	if (!shared) {
207 		desc->depth = 0;
208 		desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT |
209 				  IRQ_WAITING | IRQ_INPROGRESS);
210 		if (desc->handler->startup)
211 			desc->handler->startup(irq);
212 		else
213 			desc->handler->enable(irq);
214 	}
215 	spin_unlock_irqrestore(&desc->lock,flags);
216 
217 	new->irq = irq;
218 	register_irq_proc(irq);
219 	new->dir = NULL;
220 	register_handler_proc(irq, new);
221 
222 	return 0;
223 }
224 
225 /**
226  *	free_irq - free an interrupt
227  *	@irq: Interrupt line to free
228  *	@dev_id: Device identity to free
229  *
230  *	Remove an interrupt handler. The handler is removed and if the
231  *	interrupt line is no longer in use by any driver it is disabled.
232  *	On a shared IRQ the caller must ensure the interrupt is disabled
233  *	on the card it drives before calling this function. The function
234  *	does not return until any executing interrupts for this IRQ
235  *	have completed.
236  *
237  *	This function must not be called from interrupt context.
238  */
239 void free_irq(unsigned int irq, void *dev_id)
240 {
241 	struct irq_desc *desc;
242 	struct irqaction **p;
243 	unsigned long flags;
244 
245 	if (irq >= NR_IRQS)
246 		return;
247 
248 	desc = irq_desc + irq;
249 	spin_lock_irqsave(&desc->lock,flags);
250 	p = &desc->action;
251 	for (;;) {
252 		struct irqaction * action = *p;
253 
254 		if (action) {
255 			struct irqaction **pp = p;
256 
257 			p = &action->next;
258 			if (action->dev_id != dev_id)
259 				continue;
260 
261 			/* Found it - now remove it from the list of entries */
262 			*pp = action->next;
263 
264 			/* Currently used only by UML, might disappear one day.*/
265 #ifdef CONFIG_IRQ_RELEASE_METHOD
266 			if (desc->handler->release)
267 				desc->handler->release(irq, dev_id);
268 #endif
269 
270 			if (!desc->action) {
271 				desc->status |= IRQ_DISABLED;
272 				if (desc->handler->shutdown)
273 					desc->handler->shutdown(irq);
274 				else
275 					desc->handler->disable(irq);
276 			}
277 			spin_unlock_irqrestore(&desc->lock,flags);
278 			unregister_handler_proc(irq, action);
279 
280 			/* Make sure it's not being used on another CPU */
281 			synchronize_irq(irq);
282 			kfree(action);
283 			return;
284 		}
285 		printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
286 		spin_unlock_irqrestore(&desc->lock,flags);
287 		return;
288 	}
289 }
290 
291 EXPORT_SYMBOL(free_irq);
292 
293 /**
294  *	request_irq - allocate an interrupt line
295  *	@irq: Interrupt line to allocate
296  *	@handler: Function to be called when the IRQ occurs
297  *	@irqflags: Interrupt type flags
298  *	@devname: An ascii name for the claiming device
299  *	@dev_id: A cookie passed back to the handler function
300  *
301  *	This call allocates interrupt resources and enables the
302  *	interrupt line and IRQ handling. From the point this
303  *	call is made your handler function may be invoked. Since
304  *	your handler function must clear any interrupt the board
305  *	raises, you must take care both to initialise your hardware
306  *	and to set up the interrupt handler in the right order.
307  *
308  *	Dev_id must be globally unique. Normally the address of the
309  *	device data structure is used as the cookie. Since the handler
310  *	receives this value it makes sense to use it.
311  *
312  *	If your interrupt is shared you must pass a non NULL dev_id
313  *	as this is required when freeing the interrupt.
314  *
315  *	Flags:
316  *
317  *	SA_SHIRQ		Interrupt is shared
318  *	SA_INTERRUPT		Disable local interrupts while processing
319  *	SA_SAMPLE_RANDOM	The interrupt can be used for entropy
320  *
321  */
322 int request_irq(unsigned int irq,
323 		irqreturn_t (*handler)(int, void *, struct pt_regs *),
324 		unsigned long irqflags, const char * devname, void *dev_id)
325 {
326 	struct irqaction * action;
327 	int retval;
328 
329 	/*
330 	 * Sanity-check: shared interrupts must pass in a real dev-ID,
331 	 * otherwise we'll have trouble later trying to figure out
332 	 * which interrupt is which (messes up the interrupt freeing
333 	 * logic etc).
334 	 */
335 	if ((irqflags & SA_SHIRQ) && !dev_id)
336 		return -EINVAL;
337 	if (irq >= NR_IRQS)
338 		return -EINVAL;
339 	if (!handler)
340 		return -EINVAL;
341 
342 	action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
343 	if (!action)
344 		return -ENOMEM;
345 
346 	action->handler = handler;
347 	action->flags = irqflags;
348 	cpus_clear(action->mask);
349 	action->name = devname;
350 	action->next = NULL;
351 	action->dev_id = dev_id;
352 
353 	retval = setup_irq(irq, action);
354 	if (retval)
355 		kfree(action);
356 
357 	return retval;
358 }
359 
360 EXPORT_SYMBOL(request_irq);
361 
362