ARM Linux中断机制分析

/* arch/arm/mach-tegra/include/mach/entry-macro.S

/* Uses the GIC interrupt controller built into the cpu */

#define ICTRL_BASE (IO_CPU_VIRT + 0x40100)// #define IO_CPU_VIRT 0xFE000000

.macroget_irqnr_preamble, base, tmp

movw \base, #(ICTRL_BASE & 0x0000ffff)

movt \base, #((ICTRL_BASE & 0xffff0000) >> 16)

.endm

/* arch/arm/mach-tegra/include/mach/entry-macro.S

.macro get_irqnr_and_base, irqnr, irqstat, base, tmp

ldr \irqnr, [\base, #0x20] @ EVT_IRQ_STS

cmp \irqnr, #0x80

.endm

linux/arch/arm/kernel/irq.c

asmlinkage void __exception_irq_entry

asm_do_IRQ(unsigned int irq, struct pt_regs *regs)

{

struct pt_regs *old_regs = set_irq_regs(regs);//获得寄存器值

irq_enter();

/*

* Some hardware gives randomly wrong interrupts. Rather

* than crashing, do something sensible.

*/

if (unlikely(irq >= nr_irqs)) {

if (printk_ratelimit())

printk(KERN_WARNING "Bad IRQ%u\n", irq);

ack_bad_irq(irq);

} else {

generic_handle_irq(irq);

}

/* AT91 specific workaround */

irq_finish(irq);

irq_exit();

set_irq_regs(old_regs);

}

linux/kernel/softirq.c

voidirq_enter(void)

{

int cpu = smp_processor_id();

rcu_irq_enter();

if (idle_cpu(cpu) && !in_interrupt()) {

/* Prevent raise_softirq from needlessly waking up ksoftirqd

* here, as softirq will be serviced on return from interrupt.*/

local_bh_disable();

tick_check_idle(cpu);

_local_bh_enable();

}

__irq_enter();

}

#define __irq_enter() \

do { \

account_system_vtime(current); \

add_preempt_count(HARDIRQ_OFFSET); \

trace_hardirq_enter(); \

} while (0)

~/include /linux/Irqdesc.h

/*

* Architectures call this to let the generic IRQ layer

* handle an interrupt. If the descriptor is attached to an

* irqchip-style controller then we call the ->handle_irq() handler,

* and it calls __do_IRQ() if its attached to an irqtype-style controller.

*/

static inline void generic_handle_irq_desc(unsigned int irq,struct irq_desc *desc)

{

desc->handle_irq(irq, desc);//调用该irq注册的函数处理，该函数在注册中断时填写irq_desc结构体时指定。

}// handle_irq是