/*
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* Copyright (C) 2009 Imagination Technologies
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file COPYING in the main directory of this archive
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* for more details.
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*
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* The Meta KICK interrupt mechanism is generally a useful feature, so
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* we provide an interface for registering multiple interrupt
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* handlers. All the registered interrupt handlers are "chained". When
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* a KICK interrupt is received the first function in the list is
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* called. If that interrupt handler cannot handle the KICK the next
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* one is called, then the next until someone handles it (or we run
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* out of functions). As soon as one function handles the interrupt no
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* other handlers are called.
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*
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* The only downside of chaining interrupt handlers is that each
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* handler must be able to detect whether the KICK was intended for it
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* or not. For example, when the IPI handler runs and it sees that
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* there are no IPI messages it must not signal that the KICK was
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* handled, thereby giving the other handlers a chance to run.
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*
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* The reason that we provide our own interface for calling KICK
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* handlers instead of using the generic kernel infrastructure is that
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* the KICK handlers require access to a CPU's pTBI structure. So we
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* pass it as an argument.
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*/
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#include <linux/export.h>
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#include <linux/hardirq.h>
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#include <linux/irq.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/types.h>
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#include <asm/traps.h>
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/*
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* All accesses/manipulations of kick_handlers_list should be
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* performed while holding kick_handlers_lock.
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*/
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static DEFINE_SPINLOCK(kick_handlers_lock);
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static LIST_HEAD(kick_handlers_list);
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void kick_register_func(struct kick_irq_handler *kh)
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{
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unsigned long flags;
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spin_lock_irqsave(&kick_handlers_lock, flags);
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list_add_tail(&kh->list, &kick_handlers_list);
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spin_unlock_irqrestore(&kick_handlers_lock, flags);
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}
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EXPORT_SYMBOL(kick_register_func);
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void kick_unregister_func(struct kick_irq_handler *kh)
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{
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unsigned long flags;
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spin_lock_irqsave(&kick_handlers_lock, flags);
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list_del(&kh->list);
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spin_unlock_irqrestore(&kick_handlers_lock, flags);
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}
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EXPORT_SYMBOL(kick_unregister_func);
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TBIRES
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kick_handler(TBIRES State, int SigNum, int Triggers, int Inst, PTBI pTBI)
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{
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struct pt_regs *old_regs;
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struct kick_irq_handler *kh;
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struct list_head *lh;
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int handled = 0;
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TBIRES ret;
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head_end(State, ~INTS_OFF_MASK);
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/* If we interrupted user code handle any critical sections. */
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if (State.Sig.SaveMask & TBICTX_PRIV_BIT)
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restart_critical_section(State);
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trace_hardirqs_off();
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old_regs = set_irq_regs((struct pt_regs *)State.Sig.pCtx);
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irq_enter();
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/*
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* There is no need to disable interrupts here because we
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* can't nest KICK interrupts in a KICK interrupt handler.
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*/
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spin_lock(&kick_handlers_lock);
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list_for_each(lh, &kick_handlers_list) {
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kh = list_entry(lh, struct kick_irq_handler, list);
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ret = kh->func(State, SigNum, Triggers, Inst, pTBI, &handled);
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if (handled)
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break;
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}
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spin_unlock(&kick_handlers_lock);
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WARN_ON(!handled);
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irq_exit();
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set_irq_regs(old_regs);
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return tail_end(ret);
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}
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