r1, sp
           adrsvc        ne, lr, 1b
           @
           @ routine called with r0 = irq number, r1 = struct pt_regs *
           @
           bne    do_IRQ    @ 調(diào)用do_IRQ來(lái)實(shí)現(xiàn)具體的中斷處理
           mov  why, #0
           get_current_task tsk
           b       ret_to_user 

對(duì)于以上代碼，在很多文章中都有過(guò)分析，這里不再贅述。 

    Linux每個(gè)中斷通過(guò)一個(gè)結(jié)構(gòu)irqdesc來(lái)描述，各中斷的信息都在這個(gè)結(jié)構(gòu)中得以體現(xiàn)：

struct irqdesc {
unsigned int         nomask   : 1;            /* IRQ does not mask in IRQ   */
unsigned int         enabled  : 1;              /* IRQ is currently enabled   */
unsigned int         triggered: 1;                 /* IRQ has occurred           */
unsigned int         probing  : 1;              /* IRQ in use for a probe     */
unsigned int         probe_ok : 1;              /* IRQ can be used for probe  */
unsigned int         valid    : 1;               /* IRQ claimable       */
unsigned int         noautoenable : 1;        /* don't automatically enable IRQ */
unsigned int         unused   :25;
void (*mask_ack)(unsigned int irq);         /* Mask and acknowledge IRQ   */
void (*mask)(unsigned int irq);                /* Mask IRQ                      */
void (*unmask)(unsigned int irq);