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Diffstat (limited to 'arch/metag/kernel/kick.c')
-rw-r--r-- | arch/metag/kernel/kick.c | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/arch/metag/kernel/kick.c b/arch/metag/kernel/kick.c new file mode 100644 index 0000000..c309096 --- /dev/null +++ b/arch/metag/kernel/kick.c @@ -0,0 +1,98 @@ +/* + * 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/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); +} + +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); +} + +TBIRES +kick_handler(TBIRES State, int SigNum, int Triggers, int Inst, PTBI pTBI) +{ + 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(); + + /* + * 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); + + return tail_end(ret); +} |