/**
* handle_simple_irq - Simple and software-decoded IRQs.
* @irq: the interrupt number
* @desc: the interrupt description structure for this irq
*
* Simple interrupts are either sent from a demultiplexing interrupt
* handler or come from hardware, where no interrupt hardware control
* is necessary.
*
* Note: The caller is expected to handle the ack, clear, mask and
* unmask issues if necessary.
*/
void fastcall
handle_simple_irq(unsigned int irq, struct irq_desc *desc)
{
struct irqaction *action;
irqreturn_t action_ret;
const unsigned int cpu = smp_processor_id();
spin_lock(&desc->lock);
if (unlikely(desc->status & IRQ_INPROGRESS))
goto out_unlock;
kstat_cpu(cpu).irqs[irq]++;
action = desc->action;
if (unlikely(!action || (desc->status & IRQ_DISABLED))) {
if (desc->chip->mask)
desc->chip->mask(irq);
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
desc->status |= IRQ_PENDING;
goto out_unlock;
}
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING | IRQ_PENDING);
desc->status |= IRQ_INPROGRESS;
spin_unlock(&desc->lock);
action_ret = handle_IRQ_event(irq, action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
spin_lock(&desc->lock);
desc->status &= ~IRQ_INPROGRESS;
out_unlock:
spin_unlock(&desc->lock);
}
/**
* handle_edge_irq - edge type IRQ handler
* @irq: the interrupt number
* @desc: the interrupt description structure for this irq
*
* Interrupt occures on the falling and/or rising edge of a hardware
* signal. The occurence is latched into the irq controller hardware
* and must be acked in order to be reenabled. After the ack another
* interrupt can happen on the same source even before the first one
* is handled by the associated event handler. If this happens it
* might be necessary to disable (mask) the interrupt depending on the
* controller hardware. This requires to reenable the interrupt inside
* of the loop which handles the interrupts which have arrived while
* the handler was running. If all pending interrupts are handled, the
* loop is left.
*/
void
handle_edge_irq(unsigned int irq, struct irq_desc *desc)
{
raw_spin_lock(&desc->lock);
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
/*
* If we're currently running this IRQ, or its disabled,
* we shouldn't process the IRQ. Mark it pending, handle
* the necessary masking and go out
*/
if (unlikely((desc->status & (IRQ_INPROGRESS | IRQ_DISABLED)) ||
!desc->action)) {
desc->status |= (IRQ_PENDING | IRQ_MASKED);
mask_ack_irq(desc, irq);
goto out_unlock;
}
kstat_incr_irqs_this_cpu(irq, desc);
/* Start handling the irq */
if (desc->chip->ack)
desc->chip->ack(irq);
/* Mark the IRQ currently in progress.*/
desc->status |= IRQ_INPROGRESS;
do {
struct irqaction *action = desc->action;
irqreturn_t action_ret;
if (unlikely(!action)) {
mask_irq(desc, irq);
goto out_unlock;
}
/*
* When another irq arrived while we were handling
* one, we could have masked the irq.
* Renable it, if it was not disabled in meantime.
*/
if (unlikely((desc->status &
(IRQ_PENDING | IRQ_MASKED | IRQ_DISABLED)) ==
(IRQ_PENDING | IRQ_MASKED))) {
unmask_irq(desc, irq);
}
desc->status &= ~IRQ_PENDING;
raw_spin_unlock(&desc->lock);
action_ret = handle_IRQ_event(irq, action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
raw_spin_lock(&desc->lock);
} while ((desc->status & (IRQ_PENDING | IRQ_DISABLED)) == IRQ_PENDING);
desc->status &= ~IRQ_INPROGRESS;
out_unlock:
raw_spin_unlock(&desc->lock);
}
/**
* handle_simple_irq - Simple and software-decoded IRQs.
* @irq: the interrupt number
* @desc: the interrupt description structure for this irq
*
* Simple interrupts are either sent from a demultiplexing interrupt
* handler or come from hardware, where no interrupt hardware control
* is necessary.
*
* Note: The caller is expected to handle the ack, clear, mask and
* unmask issues if necessary.
*/
void
handle_simple_irq(unsigned int irq, struct irq_desc *desc)
{
struct irqaction *action;
irqreturn_t action_ret;
spin_lock(&desc->lock);
if (unlikely(desc->status & IRQ_INPROGRESS))
goto out_unlock;
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
kstat_incr_irqs_this_cpu(irq, desc);
action = desc->action;
if (unlikely(!action || (desc->status & IRQ_DISABLED)))
goto out_unlock;
desc->status |= IRQ_INPROGRESS;
spin_unlock(&desc->lock);
action_ret = handle_IRQ_event(irq, action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
spin_lock(&desc->lock);
desc->status &= ~IRQ_INPROGRESS;
out_unlock:
spin_unlock(&desc->lock);
}
static void do_8259A_IRQ(unsigned int irq, struct pt_regs * regs)
{
struct irqServer * iServer;
struct irqDescriptor *desc = &irq_desc[irq];
{
unsigned int status;
mask_and_ack_8259A(irq);
status = desc->id_status & ~(IRQ_REPLAY | IRQ_WAITING);
iServer = NULL;
if (!(status & (IRQ_DISABLED | IRQ_INPROGRESS))) {
iServer = desc->id_server;
status |= IRQ_INPROGRESS;
}
desc->id_status = status;
}
/* Exit early if we had no action or it was disabled */
if (!iServer)
return;
handle_IRQ_event(irq, regs, iServer);
{
unsigned int status = desc->id_status & ~IRQ_INPROGRESS;
desc->id_status = status;
if (!(status & IRQ_DISABLED))
enable_8259A_irq(irq);
}
}
/**
* handle_level_irq - Level type irq handler
* @irq: the interrupt number
* @desc: the interrupt description structure for this irq
*
* Level type interrupts are active as long as the hardware line has
* the active level. This may require to mask the interrupt and unmask
* it after the associated handler has acknowledged the device, so the
* interrupt line is back to inactive.
*/
void
handle_level_irq(unsigned int irq, struct irq_desc *desc)
{
struct irqaction *action;
irqreturn_t action_ret;
spin_lock(&desc->lock);
/*
调用中断线所属的中断控制的mask_ack函数.
如果没有定义该函数，就调用mask，然后调用ack函数.
总之，对于水平触发的来说，它就是屏蔽当前的中断线，应当当前中断..
比如ARM来说，就是清除SRCPND、SRCINTPND寄存器的位.
*/
mask_ack_irq(desc, irq);
desc = irq_remap_to_desc(irq, desc);
/*
在多处理器的系统上，可能中断已经被另外一个CPU开始处理..但是该CPU也
进入到进入处理..此时另外处理的CPU会设置状态为正在处理当中..
因此，当前CPU就直接退出。
*/
if (unlikely(desc->status & IRQ_INPROGRESS))
goto out_unlock;
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
kstat_incr_irqs_this_cpu(irq, desc);
/*
* If its disabled or no action available
* keep it masked and get out of here
*/
action = desc->action;
/*
如果该中断线上没有中断处理函数，那就直接退出.
或者说，该中断线当前状态是DISABLED，也就是要屏蔽掉该中断的..?
但是由于某种原因还产生了中断?不过确实状态就是DISABLED，那也直接退出。
*/
if (unlikely(!action || (desc->status & IRQ_DISABLED)))
goto out_unlock;
//好这里设置为正在处理当中...避免多处理的竞争...哦。这断代码的执行
//是在上锁的状态下的..下面解锁.
desc->status |= IRQ_INPROGRESS;
spin_unlock(&desc->lock);
action_ret = handle_IRQ_event(irq, action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
spin_lock(&desc->lock);
//处理完成之后..这里要修改当前中断线的状态了..一样是上锁.
desc->status &= ~IRQ_INPROGRESS;
//该中断线的状态是不屏蔽的，并且有unmask函数..那就调用unmask，它就是
//取消屏蔽该中断线...因为水平电流处理函数在一开始有mask_ack_irq给屏蔽掉了中断线了
if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
desc->chip->unmask(irq);
out_unlock:
spin_unlock(&desc->lock);
}
/**
* handle_fasteoi_irq - irq handler for transparent controllers
* @irq: the interrupt number
* @desc: the interrupt description structure for this irq
*
* Only a single callback will be issued to the chip: an ->eoi()
* call when the interrupt has been serviced. This enables support
* for modern forms of interrupt handlers, which handle the flow
* details in hardware, transparently.
*/
void
handle_fasteoi_irq(unsigned int irq, struct irq_desc *desc)
{
struct irqaction *action;
irqreturn_t action_ret;
raw_spin_lock(&desc->lock);
if (unlikely(desc->status & IRQ_INPROGRESS))
goto out;
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
kstat_incr_irqs_this_cpu(irq, desc);
/*
* If its disabled or no action available
* then mask it and get out of here:
*/
action = desc->action;
if (unlikely(!action || (desc->status & IRQ_DISABLED))) {
desc->status |= IRQ_PENDING;
mask_irq(desc);
goto out;
}
if (desc->status & IRQ_ONESHOT)
mask_irq(desc);
desc->status |= IRQ_INPROGRESS;
desc->status &= ~IRQ_PENDING;
raw_spin_unlock(&desc->lock);
action_ret = handle_IRQ_event(irq, action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
raw_spin_lock(&desc->lock);
desc->status &= ~IRQ_INPROGRESS;
#ifdef CONFIG_IPIPE
if (!(desc->status & IRQ_MASKED))
desc->irq_data.chip->irq_unmask(&desc->irq_data);
out:
#else
out:
desc->irq_data.chip->irq_eoi(&desc->irq_data);
#endif
raw_spin_unlock(&desc->lock);
}
/**
* handle_percpu_IRQ - Per CPU local irq handler
* @irq: the interrupt number
* @desc: the interrupt description structure for this irq
*
* Per CPU interrupts on SMP machines without locking requirements
*/
void fastcall
handle_percpu_irq(unsigned int irq, struct irq_desc *desc)
{
irqreturn_t action_ret;
kstat_this_cpu.irqs[irq]++;
if (desc->chip->ack)
desc->chip->ack(irq);
action_ret = handle_IRQ_event(irq, desc->action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
if (desc->chip->eoi)
desc->chip->eoi(irq);
}
/**
* handle_percpu_irq - Per CPU local irq handler
* @irq: the interrupt number
* @desc: the interrupt description structure for this irq
*
* Per CPU interrupts on SMP machines without locking requirements
*/
void
handle_percpu_irq(unsigned int irq, struct irq_desc *desc)
{
irqreturn_t action_ret;
kstat_incr_irqs_this_cpu(irq, desc);
if (desc->irq_data.chip->irq_ack)
desc->irq_data.chip->irq_ack(&desc->irq_data);
action_ret = handle_IRQ_event(irq, desc->action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
if (desc->irq_data.chip->irq_eoi)
desc->irq_data.chip->irq_eoi(&desc->irq_data);
}
/**
* handle_percpu_IRQ - Per CPU local irq handler
* @irq: the interrupt number
* @desc: the interrupt description structure for this irq
*
* Per CPU interrupts on SMP machines without locking requirements
*/
void
handle_percpu_irq(unsigned int irq, struct irq_desc *desc)
{
irqreturn_t action_ret;
kstat_incr_irqs_this_cpu(irq, desc);
if (desc->chip->ack)
desc->chip->ack(irq);
action_ret = handle_IRQ_event(irq, desc->action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
if (desc->chip->eoi) {
desc->chip->eoi(irq);
desc = irq_remap_to_desc(irq, desc);
}
}
/**
* handle_fasteoi_irq - irq handler for transparent controllers
* @irq: the interrupt number
* @desc: the interrupt description structure for this irq
*
* Only a single callback will be issued to the chip: an ->eoi()
* call when the interrupt has been serviced. This enables support
* for modern forms of interrupt handlers, which handle the flow
* details in hardware, transparently.
*/
void fastcall
handle_fasteoi_irq(unsigned int irq, struct irq_desc *desc)
{
unsigned int cpu = smp_processor_id();
struct irqaction *action;
irqreturn_t action_ret;
spin_lock(&desc->lock);
if (unlikely(desc->status & IRQ_INPROGRESS))
goto out;
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
kstat_cpu(cpu).irqs[irq]++;
/*
* If its disabled or no action available
* then mask it and get out of here:
*/
action = desc->action;
if (unlikely(!action || (desc->status & IRQ_DISABLED))) {
desc->status |= IRQ_PENDING;
if (desc->chip->mask)
desc->chip->mask(irq);
goto out;
}
desc->status |= IRQ_INPROGRESS;
desc->status &= ~IRQ_PENDING;
spin_unlock(&desc->lock);
action_ret = handle_IRQ_event(irq, action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
spin_lock(&desc->lock);
desc->status &= ~IRQ_INPROGRESS;
out:
desc->chip->eoi(irq);
spin_unlock(&desc->lock);
}
/**
* handle_level_irq - Level type irq handler
* @irq: the interrupt number
* @desc: the interrupt description structure for this irq
*
* Level type interrupts are active as long as the hardware line has
* the active level. This may require to mask the interrupt and unmask
* it after the associated handler has acknowledged the device, so the
* interrupt line is back to inactive.
*/
void
handle_level_irq(unsigned int irq, struct irq_desc *desc)
{
struct irqaction *action;
irqreturn_t action_ret;
spin_lock(&desc->lock);
mask_ack_irq(desc, irq);
if (unlikely(desc->status & IRQ_INPROGRESS))
goto out_unlock;
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
kstat_incr_irqs_this_cpu(irq, desc);
/*
* If its disabled or no action available
* keep it masked and get out of here
*/
action = desc->action;
if (unlikely(!action || (desc->status & IRQ_DISABLED)))
{
printk(KERN_ERR "IRQ %d enter bad status!\n", irq);
goto out_unlock;
}
desc->status |= IRQ_INPROGRESS;
spin_unlock(&desc->lock);
action_ret = handle_IRQ_event(irq, action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
spin_lock(&desc->lock);
desc->status &= ~IRQ_INPROGRESS;
if (unlikely(desc->status & IRQ_ONESHOT))
desc->status |= IRQ_MASKED;
else if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
desc->chip->unmask(irq);
out_unlock:
spin_unlock(&desc->lock);
}
static void handle_prio_irq(unsigned int irq, struct irq_desc *desc)
{
unsigned int cpu = smp_processor_id();
struct irqaction *action;
irqreturn_t action_ret;
spin_lock(&desc->lock);
BUG_ON(desc->status & IRQ_INPROGRESS);
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
kstat_cpu(cpu).irqs[irq]++;
action = desc->action;
if (unlikely(!action || (desc->status & IRQ_DISABLED)))
goto out_mask;
desc->status |= IRQ_INPROGRESS;
spin_unlock(&desc->lock);
action_ret = handle_IRQ_event(irq, action);
/* XXX: There is no direct way to access noirqdebug, so check
* unconditionally for spurious irqs...
* Maybe this function should go to kernel/irq/chip.c? */
note_interrupt(irq, desc, action_ret);
spin_lock(&desc->lock);
desc->status &= ~IRQ_INPROGRESS;
if (desc->status & IRQ_DISABLED)
out_mask:
desc->chip->mask(irq);
/* ack unconditionally to unmask lower prio irqs */
desc->chip->ack(irq);
spin_unlock(&desc->lock);
}
/**
* handle_level_irq - Level type irq handler
* @irq: the interrupt number
* @desc: the interrupt description structure for this irq
*
* Level type interrupts are active as long as the hardware line has
* the active level. This may require to mask the interrupt and unmask
* it after the associated handler has acknowledged the device, so the
* interrupt line is back to inactive.
*/
void
handle_level_irq(unsigned int irq, struct irq_desc *desc)
{
struct irqaction *action;
irqreturn_t action_ret;
raw_spin_lock(&desc->lock);
#ifndef CONFIG_IPIPE
mask_ack_irq(desc);
#endif
if (unlikely(desc->status & IRQ_INPROGRESS))
goto out_unlock;
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
kstat_incr_irqs_this_cpu(irq, desc);
/*
* If its disabled or no action available
* keep it masked and get out of here
*/
action = desc->action;
if (unlikely(!action || (desc->status & IRQ_DISABLED)))
goto out_unlock;
desc->status |= IRQ_INPROGRESS;
raw_spin_unlock(&desc->lock);
action_ret = handle_IRQ_event(irq, action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
raw_spin_lock(&desc->lock);
desc->status &= ~IRQ_INPROGRESS;
if (!(desc->status & (IRQ_DISABLED | IRQ_ONESHOT)))
unmask_irq(desc);
out_unlock:
raw_spin_unlock(&desc->lock);
}
/**
* handle_level_irq - Level type irq handler
* @irq: the interrupt number
* @desc: the interrupt description structure for this irq
*
* Level type interrupts are active as long as the hardware line has
* the active level. This may require to mask the interrupt and unmask
* it after the associated handler has acknowledged the device, so the
* interrupt line is back to inactive.
*/
void
handle_level_irq(unsigned int irq, struct irq_desc *desc)
{
unsigned int cpu = smp_processor_id();
struct irqaction *action;
irqreturn_t action_ret;
spin_lock(&desc->lock);
mask_ack_irq(desc, irq);
if (unlikely(desc->status & IRQ_INPROGRESS))
goto out_unlock;
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
kstat_cpu(cpu).irqs[irq]++;
/*
* If its disabled or no action available
* keep it masked and get out of here
*/
action = desc->action;
if (unlikely(!action || (desc->status & IRQ_DISABLED)))
goto out_unlock;
desc->status |= IRQ_INPROGRESS;
spin_unlock(&desc->lock);
action_ret = handle_IRQ_event(irq, action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
spin_lock(&desc->lock);
desc->status &= ~IRQ_INPROGRESS;
if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
desc->chip->unmask(irq);
out_unlock:
spin_unlock(&desc->lock);
}
/*
* PIIX4-8259 master/virtual functions to handle interrupt requests
* from legacy devices: floppy, parallel, serial, rtc.
*
* None of these get Cobalt APIC entries, neither do they have IDT
* entries. These interrupts are purely virtual and distributed from
* the 'master' interrupt source: CO_IRQ_8259.
*
* When the 8259 interrupts its handler figures out which of these
* devices is interrupting and dispatches to its handler.
*
* CAREFUL: devices see the 'virtual' interrupt only. Thus disable/
* enable_irq gets the right irq. This 'master' irq is never directly
* manipulated by any driver.
*/
static irqreturn_t piix4_master_intr(int irq, void *dev_id)
{
int realirq;
irq_desc_t *desc;
unsigned long flags;
spin_lock_irqsave(&i8259A_lock, flags);
/* Find out what's interrupting in the PIIX4 master 8259 */
outb(0x0c, 0x20); /* OCW3 Poll command */
realirq = inb(0x20);
/*
* Bit 7 == 0 means invalid/spurious
*/
if (unlikely(!(realirq & 0x80)))
goto out_unlock;
realirq &= 7;
if (unlikely(realirq == 2)) {
outb(0x0c, 0xa0);
realirq = inb(0xa0);
if (unlikely(!(realirq & 0x80)))
goto out_unlock;
realirq = (realirq & 7) + 8;
}
/* mask and ack interrupt */
cached_irq_mask |= 1 << realirq;
if (unlikely(realirq > 7)) {
inb(0xa1);
outb(cached_slave_mask, 0xa1);
outb(0x60 + (realirq & 7), 0xa0);
outb(0x60 + 2, 0x20);
} else {
inb(0x21);
outb(cached_master_mask, 0x21);
outb(0x60 + realirq, 0x20);
}
spin_unlock_irqrestore(&i8259A_lock, flags);
desc = irq_desc + realirq;
/*
* handle this 'virtual interrupt' as a Cobalt one now.
*/
kstat_cpu(smp_processor_id()).irqs[realirq]++;
if (likely(desc->action != NULL))
handle_IRQ_event(realirq, desc->action);
if (!(desc->status & IRQ_DISABLED))
enable_8259A_irq(realirq);
return IRQ_HANDLED;
out_unlock:
spin_unlock_irqrestore(&i8259A_lock, flags);
return IRQ_NONE;
}
/**
* __do_IRQ - original all in one highlevel IRQ handler
* @irq: the interrupt number
*
* __do_IRQ handles all normal device IRQ's (the special
* SMP cross-CPU interrupts have their own specific
* handlers).
*
* This is the original x86 implementation which is used for every
* interrupt type.
*/
unsigned int __do_IRQ(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
struct irqaction *action;
unsigned int status;
kstat_incr_irqs_this_cpu(irq, desc);
if (CHECK_IRQ_PER_CPU(desc->status)) {
irqreturn_t action_ret;
/*
* No locking required for CPU-local interrupts:
*/
if (desc->chip->ack)
desc->chip->ack(irq);
if (likely(!(desc->status & IRQ_DISABLED))) {
action_ret = handle_IRQ_event(irq, desc->action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
}
desc->chip->end(irq);
return 1;
}
spin_lock(&desc->lock);
if (desc->chip->ack)
desc->chip->ack(irq);
/*
* REPLAY is when Linux resends an IRQ that was dropped earlier
* WAITING is used by probe to mark irqs that are being tested
*/
status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
status |= IRQ_PENDING; /* we _want_ to handle it */
/*
* If the IRQ is disabled for whatever reason, we cannot
* use the action we have.
*/
action = NULL;
if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
action = desc->action;
status &= ~IRQ_PENDING; /* we commit to handling */
status |= IRQ_INPROGRESS; /* we are handling it */
}
desc->status = status;
/*
* If there is no IRQ handler or it was disabled, exit early.
* Since we set PENDING, if another processor is handling
* a different instance of this same irq, the other processor
* will take care of it.
*/
if (unlikely(!action))
goto out;
/*
* Edge triggered interrupts need to remember
* pending events.
* This applies to any hw interrupts that allow a second
* instance of the same irq to arrive while we are in do_IRQ
* or in the handler. But the code here only handles the _second_
* instance of the irq, not the third or fourth. So it is mostly
* useful for irq hardware that does not mask cleanly in an
* SMP environment.
*/
for (;;) {
irqreturn_t action_ret;
spin_unlock(&desc->lock);
action_ret = handle_IRQ_event(irq, action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
spin_lock(&desc->lock);
if (likely(!(desc->status & IRQ_PENDING)))
break;
desc->status &= ~IRQ_PENDING;
}
desc->status &= ~IRQ_INPROGRESS;
out:
/*
* The ->end() handler has to deal with interrupts which got
* disabled while the handler was running.
*/
desc->chip->end(irq);
spin_unlock(&desc->lock);
return 1;
}
/**
* handle_edge_irq - edge type IRQ handler
* @irq: the interrupt number
* @desc: the interrupt description structure for this irq
*
* Interrupt occures on the falling and/or rising edge of a hardware
* signal. The occurence is latched into the irq controller hardware
* and must be acked in order to be reenabled. After the ack another
* interrupt can happen on the same source even before the first one
* is handled by the assosiacted event handler. If this happens it
* might be necessary to disable (mask) the interrupt depending on the
* controller hardware. This requires to reenable the interrupt inside
* of the loop which handles the interrupts which have arrived while
* the handler was running. If all pending interrupts are handled, the
* loop is left.
*/
void
handle_edge_irq(unsigned int irq, struct irq_desc *desc)
{
spin_lock(&desc->lock);
/*
需要同水平电流处理函数对比，这里并没有调用mask_ack函数，来屏蔽中断线.
*/
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
/*
* If we're currently running this IRQ, or its disabled,
* we shouldn't process the IRQ. Mark it pending, handle
* the necessary masking and go out
*/
/*
如果边缘电平的触发，然后引起了一个中断，处理函数会对该中断线设置为正在处理当中.
也就是IRQ_INPROGRESS标记..此时判断判断IRQ_INPROGRESS如果置位，代表是又一个中断发生了
因为是边缘触发的..那就设置status为PENDING挂机，等待处理.
*/
if (unlikely((desc->status & (IRQ_INPROGRESS | IRQ_DISABLED)) ||
!desc->action)) {
desc->status |= (IRQ_PENDING | IRQ_MASKED);
//已经PENDING了一次处理，这时候特殊处理，屏蔽掉该中断..然后应答该中断线.
//上面status设置为IRQ_MASKED，也可以证实这个情况.
mask_ack_irq(desc, irq);
desc = irq_remap_to_desc(irq, desc);
goto out_unlock;
}
kstat_incr_irqs_this_cpu(irq, desc);
/*
当然..更一般的情况是下面这种...它会调用应答ack.!!注意注意...和水平触发的区别来了.
水平触发是mask_ack!!!
*/
/* Start handling the irq */
if (desc->chip->ack)
desc->chip->ack(irq);
desc = irq_remap_to_desc(irq, desc);
/* Mark the IRQ currently in progress.*/
desc->status |= IRQ_INPROGRESS;
do {
struct irqaction *action = desc->action;
irqreturn_t action_ret;
//如果该中断线没有中断处理函数..那屏蔽掉该中断线..然后退出.
if (unlikely(!action)) {
desc->chip->mask(irq);
goto out_unlock;
}
/*
* When another irq arrived while we were handling
* one, we could have masked the irq.
* Renable it, if it was not disabled in meantime.
*/
if (unlikely((desc->status &
(IRQ_PENDING | IRQ_MASKED | IRQ_DISABLED)) ==
(IRQ_PENDING | IRQ_MASKED))) {
//前面有看到..到中断处理过程中再次引起中断，就会挂机该中断，然后屏蔽中断线.
//此时这里，就是重新设置为不屏蔽的..
desc->chip->unmask(irq);
desc->status &= ~IRQ_MASKED;
}
desc->status &= ~IRQ_PENDING;
spin_unlock(&desc->lock);
//释放锁...进入到处理中断函数中去.
action_ret = handle_IRQ_event(irq, action);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
//中断处理函数处理完成了...然后还要继续判断在处理过程中是否有新的中断产生.
spin_lock(&desc->lock);
//因为对于边缘触发的中断来说，它的处理过程，可能有引起了中断了的发生了.
//此时会设置status带IRQ_PENDING标记.那就需要在继续执行一遍处理函数.
} while ((desc->status & (IRQ_PENDING | IRQ_DISABLED)) == IRQ_PENDING);
desc->status &= ~IRQ_INPROGRESS;
out_unlock:
spin_unlock(&desc->lock);
}
/*
* Recovery handler for misrouted interrupts.
*/
static int try_one_irq(int irq, struct irq_desc *desc)
{
struct irqaction *action;
int ok = 0, work = 0;
spin_lock(&desc->lock);
/* Already running on another processor */
if (desc->status & IRQ_INPROGRESS) {
/*
* Already running: If it is shared get the other
* CPU to go looking for our mystery interrupt too
*/
if (desc->action && (desc->action->flags & IRQF_SHARED))
desc->status |= IRQ_PENDING;
spin_unlock(&desc->lock);
return ok;
}
/* Honour the normal IRQ locking */
desc->status |= IRQ_INPROGRESS;
action = desc->action;
spin_unlock(&desc->lock);
while (action) {
/* Only shared IRQ handlers are safe to call */
if (action->flags & IRQF_SHARED) {
if (action->handler(irq, action->dev_id) ==
IRQ_HANDLED)
ok = 1;
}
action = action->next;
}
local_irq_disable();
/* Now clean up the flags */
spin_lock(&desc->lock);
action = desc->action;
/*
* While we were looking for a fixup someone queued a real
* IRQ clashing with our walk:
*/
while ((desc->status & IRQ_PENDING) && action) {
/*
* Perform real IRQ processing for the IRQ we deferred
*/
work = 1;
spin_unlock(&desc->lock);
handle_IRQ_event(irq, action);
spin_lock(&desc->lock);
desc->status &= ~IRQ_PENDING;
}
desc->status &= ~IRQ_INPROGRESS;
/*
* If we did actual work for the real IRQ line we must let the
* IRQ controller clean up too
*/
if (work && desc->chip && desc->chip->end)
desc->chip->end(irq);
spin_unlock(&desc->lock);
return ok;
}
/**
* __do_IRQ - original all in one highlevel IRQ handler
* @irq: the interrupt number
* @regs: pointer to a register structure
*
* __do_IRQ handles all normal device IRQ's (the special
* SMP cross-CPU interrupts have their own specific
* handlers).
*
* This is the original x86 implementation which is used for every
* interrupt type.
*/
fastcall notrace unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs)
{
struct irq_desc *desc = irq_desc + irq;
struct irqaction *action;
unsigned int status;
kstat_this_cpu.irqs[irq]++;
if (CHECK_IRQ_PER_CPU(desc->status)) {
irqreturn_t action_ret;
/*
* No locking required for CPU-local interrupts:
*/
if (desc->chip->ack)
desc->chip->ack(irq);
action_ret = handle_IRQ_event(irq, regs, desc->action);
desc->chip->end(irq);
return 1;
}
/*
* If the task is currently running in user mode, don't
* detect soft lockups. If CONFIG_DETECT_SOFTLOCKUP is not
* configured, this should be optimized out.
*/
if (user_mode(regs))
touch_softlockup_watchdog();
spin_lock(&desc->lock);
if (desc->chip->ack)
desc->chip->ack(irq);
/*
* REPLAY is when Linux resends an IRQ that was dropped earlier
* WAITING is used by probe to mark irqs that are being tested
*/
status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
status |= IRQ_PENDING; /* we _want_ to handle it */
/*
* If the IRQ is disabled for whatever reason, we cannot
* use the action we have.
*/
action = NULL;
if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
action = desc->action;
status &= ~IRQ_PENDING; /* we commit to handling */
status |= IRQ_INPROGRESS; /* we are handling it */
}
desc->status = status;
/*
* If there is no IRQ handler or it was disabled, exit early.
* Since we set PENDING, if another processor is handling
* a different instance of this same irq, the other processor
* will take care of it.
*/
if (unlikely(!action))
goto out;
/*
* hardirq redirection to the irqd process context:
*/
if (redirect_hardirq(desc))
goto out_no_end;
/*
* Edge triggered interrupts need to remember
* pending events.
* This applies to any hw interrupts that allow a second
* instance of the same irq to arrive while we are in do_IRQ
* or in the handler. But the code here only handles the _second_
* instance of the irq, not the third or fourth. So it is mostly
* useful for irq hardware that does not mask cleanly in an
* SMP environment.
*/
for (;;) {
irqreturn_t action_ret;
spin_unlock(&desc->lock);
action_ret = handle_IRQ_event(irq, regs, action);
spin_lock(&desc->lock);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret, regs);
if (likely(!(desc->status & IRQ_PENDING)))
break;
desc->status &= ~IRQ_PENDING;
}
desc->status &= ~IRQ_INPROGRESS;
out:
/*
* The ->end() handler has to deal with interrupts which got
* disabled while the handler was running.
*/
desc->chip->end(irq);
out_no_end:
spin_unlock(&desc->lock);
return 1;
}
/*
* do_IRQ handles all normal device IRQ's (the special
* SMP cross-CPU interrupts have their own specific
* handlers).
*/
asmlinkage unsigned int do_IRQ(int irq, struct pt_regs *regs)
{
/*
* We ack quickly, we don't want the irq controller
* thinking we're snobs just because some other CPU has
* disabled global interrupts (we have already done the
* INT_ACK cycles, it's too late to try to pretend to the
* controller that we aren't taking the interrupt).
*
* 0 return value means that this irq is already being
* handled by some other CPU. (or is disabled)
*/
int cpu = smp_processor_id();
irq_desc_t *desc = irq_desc + irq;
struct irqaction * action;
unsigned int status;
kstat.irqs[cpu][irq]++;
spin_lock(&desc->lock);
desc->handler->ack(irq);
/*
REPLAY is when Linux resends an IRQ that was dropped earlier
WAITING is used by probe to mark irqs that are being tested
*/
status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
status |= IRQ_PENDING; /* we _want_ to handle it */
/*
* If the IRQ is disabled for whatever reason, we cannot
* use the action we have.
*/
action = NULL;
if (!(status & (IRQ_DISABLED | IRQ_INPROGRESS))) {
action = desc->action;
status &= ~IRQ_PENDING; /* we commit to handling */
status |= IRQ_INPROGRESS; /* we are handling it */
}
desc->status = status;
/*
* If there is no IRQ handler or it was disabled, exit early.
Since we set PENDING, if another processor is handling
a different instance of this same irq, the other processor
will take care of it.
*/
if (!action) {
goto out;
}
/*
* Edge triggered interrupts need to remember
* pending events.
* This applies to any hw interrupts that allow a second
* instance of the same irq to arrive while we are in do_IRQ
* or in the handler. But the code here only handles the _second_
* instance of the irq, not the third or fourth. So it is mostly
* useful for irq hardware that does not mask cleanly in an
* SMP environment.
*/
for (;;) {
spin_unlock(&desc->lock);
handle_IRQ_event(irq, regs, action);
spin_lock(&desc->lock);
if (!(desc->status & IRQ_PENDING))
break;
desc->status &= ~IRQ_PENDING;
}
desc->status &= ~IRQ_INPROGRESS;
out:
/*
* The ->end() handler has to deal with interrupts which got
* disabled while the handler was running.
*/
desc->handler->end(irq);
spin_unlock(&desc->lock);
if (softirq_pending(cpu))
do_softirq();
return 1;
}