[deliverable/linux.git] / arch / metag / kernel / kick.c

/*
 *  Copyright (C) 2009 Imagination Technologies
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 *
 * The Meta KICK interrupt mechanism is generally a useful feature, so
 * we provide an interface for registering multiple interrupt
 * handlers. All the registered interrupt handlers are "chained". When
 * a KICK interrupt is received the first function in the list is
 * called. If that interrupt handler cannot handle the KICK the next
 * one is called, then the next until someone handles it (or we run
 * out of functions). As soon as one function handles the interrupt no
 * other handlers are called.
 *
 * The only downside of chaining interrupt handlers is that each
 * handler must be able to detect whether the KICK was intended for it
 * or not.  For example, when the IPI handler runs and it sees that
 * there are no IPI messages it must not signal that the KICK was
 * handled, thereby giving the other handlers a chance to run.
 *
 * The reason that we provide our own interface for calling KICK
 * handlers instead of using the generic kernel infrastructure is that
 * the KICK handlers require access to a CPU's pTBI structure. So we
 * pass it as an argument.
 */
#include <linux/export.h>
#include <linux/hardirq.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/types.h>

#include <asm/traps.h>

/*
 * All accesses/manipulations of kick_handlers_list should be
 * performed while holding kick_handlers_lock.
 */
static DEFINE_SPINLOCK(kick_handlers_lock);
static LIST_HEAD(kick_handlers_list);

void kick_register_func(struct kick_irq_handler *kh)
{
	unsigned long flags;

	spin_lock_irqsave(&kick_handlers_lock, flags);

	list_add_tail(&kh->list, &kick_handlers_list);

	spin_unlock_irqrestore(&kick_handlers_lock, flags);
}
EXPORT_SYMBOL(kick_register_func);

void kick_unregister_func(struct kick_irq_handler *kh)
{
	unsigned long flags;

	spin_lock_irqsave(&kick_handlers_lock, flags);

	list_del(&kh->list);

	spin_unlock_irqrestore(&kick_handlers_lock, flags);
}
EXPORT_SYMBOL(kick_unregister_func);

TBIRES
kick_handler(TBIRES State, int SigNum, int Triggers, int Inst, PTBI pTBI)
{
	struct pt_regs *old_regs;
	struct kick_irq_handler *kh;
	struct list_head *lh;
	int handled = 0;
	TBIRES ret;

	head_end(State, ~INTS_OFF_MASK);

	/* If we interrupted user code handle any critical sections. */
	if (State.Sig.SaveMask & TBICTX_PRIV_BIT)
		restart_critical_section(State);

	trace_hardirqs_off();

	old_regs = set_irq_regs((struct pt_regs *)State.Sig.pCtx);
	irq_enter();

	/*
	 * There is no need to disable interrupts here because we
	 * can't nest KICK interrupts in a KICK interrupt handler.
	 */
	spin_lock(&kick_handlers_lock);

	list_for_each(lh, &kick_handlers_list) {
		kh = list_entry(lh, struct kick_irq_handler, list);

		ret = kh->func(State, SigNum, Triggers, Inst, pTBI, &handled);
		if (handled)
			break;
	}

	spin_unlock(&kick_handlers_lock);

	WARN_ON(!handled);

	irq_exit();
	set_irq_regs(old_regs);

	return tail_end(ret);
}
Commit	Line	Data
ac919f08 JH	1	/*
	2	* Copyright (C) 2009 Imagination Technologies
	3	*
	4	* This file is subject to the terms and conditions of the GNU General Public
	5	* License. See the file COPYING in the main directory of this archive
	6	* for more details.
	7	*
	8	* The Meta KICK interrupt mechanism is generally a useful feature, so
	9	* we provide an interface for registering multiple interrupt
	10	* handlers. All the registered interrupt handlers are "chained". When
	11	* a KICK interrupt is received the first function in the list is
	12	* called. If that interrupt handler cannot handle the KICK the next
	13	* one is called, then the next until someone handles it (or we run
	14	* out of functions). As soon as one function handles the interrupt no
	15	* other handlers are called.
	16	*
	17	* The only downside of chaining interrupt handlers is that each
	18	* handler must be able to detect whether the KICK was intended for it
	19	* or not. For example, when the IPI handler runs and it sees that
	20	* there are no IPI messages it must not signal that the KICK was
	21	* handled, thereby giving the other handlers a chance to run.
	22	*
	23	* The reason that we provide our own interface for calling KICK
	24	* handlers instead of using the generic kernel infrastructure is that
	25	* the KICK handlers require access to a CPU's pTBI structure. So we
	26	* pass it as an argument.
	27	*/
aa29ec5f	28	#include <linux/export.h>
f6b30d32 JH	29	#include <linux/hardirq.h>
f6b30d32 JH	30	#include <linux/irq.h>
ac919f08 JH	31	#include <linux/kernel.h>
	32	#include <linux/mm.h>
	33	#include <linux/types.h>
	34
	35	#include <asm/traps.h>
	36
	37	/*
	38	* All accesses/manipulations of kick_handlers_list should be
	39	* performed while holding kick_handlers_lock.
	40	*/
	41	static DEFINE_SPINLOCK(kick_handlers_lock);
	42	static LIST_HEAD(kick_handlers_list);
	43
	44	void kick_register_func(struct kick_irq_handler *kh)
	45	{
	46	unsigned long flags;
	47
	48	spin_lock_irqsave(&kick_handlers_lock, flags);
	49
	50	list_add_tail(&kh->list, &kick_handlers_list);
	51
	52	spin_unlock_irqrestore(&kick_handlers_lock, flags);
	53	}
aa29ec5f	54	EXPORT_SYMBOL(kick_register_func);
ac919f08 JH	55
	56	void kick_unregister_func(struct kick_irq_handler *kh)
	57	{
	58	unsigned long flags;
	59
	60	spin_lock_irqsave(&kick_handlers_lock, flags);
	61
	62	list_del(&kh->list);
	63
	64	spin_unlock_irqrestore(&kick_handlers_lock, flags);
	65	}
aa29ec5f	66	EXPORT_SYMBOL(kick_unregister_func);
ac919f08 JH	67
	68	TBIRES
	69	kick_handler(TBIRES State, int SigNum, int Triggers, int Inst, PTBI pTBI)
	70	{
f6b30d32	71	struct pt_regs *old_regs;
ac919f08 JH	72	struct kick_irq_handler *kh;
	73	struct list_head *lh;
	74	int handled = 0;
	75	TBIRES ret;
	76
	77	head_end(State, ~INTS_OFF_MASK);
	78
	79	/* If we interrupted user code handle any critical sections. */
	80	if (State.Sig.SaveMask & TBICTX_PRIV_BIT)
	81	restart_critical_section(State);
	82
	83	trace_hardirqs_off();
	84
f6b30d32 JH	85	old_regs = set_irq_regs((struct pt_regs *)State.Sig.pCtx);
	86	irq_enter();
	87
ac919f08 JH	88	/*
	89	* There is no need to disable interrupts here because we
	90	* can't nest KICK interrupts in a KICK interrupt handler.
	91	*/
	92	spin_lock(&kick_handlers_lock);
	93
	94	list_for_each(lh, &kick_handlers_list) {
	95	kh = list_entry(lh, struct kick_irq_handler, list);
	96
	97	ret = kh->func(State, SigNum, Triggers, Inst, pTBI, &handled);
	98	if (handled)
	99	break;
	100	}
	101
	102	spin_unlock(&kick_handlers_lock);
	103
	104	WARN_ON(!handled);
	105
f6b30d32 JH	106	irq_exit();
	107	set_irq_regs(old_regs);
	108
ac919f08 JH	109	return tail_end(ret);
ac919f08 JH	110	}