arm linux 下中断流程简要分析初始化

0; i < 4; i++) {

pend = __raw_readl(S3C2410_INTPND);

if (pend == 0 || pend == last)

break;

__raw_writel(pend, S3C2410_SRCPND);

__raw_writel(pend, S3C2410_INTPND);

printk("irq: clearing pending status %08x/n", (int)pend);

last = pend;

}

last = 0;

for (i = 0; i < 4; i++) {

pend = __raw_readl(S3C2410_SUBSRCPND);

if (pend == 0 || pend == last)

break;

printk("irq: clearing subpending status %08x/n", (int)pend);

__raw_writel(pend, S3C2410_SUBSRCPND);

last = pend;

}

/* register the main interrupts */

/*注册主要的中断*/

irqdbf("s3c2410_init_irq: registering s3c2410 interrupt handlers/n");

for (irqno = IRQ_EINT4t7; irqno <= IRQ_ADCPARENT; irqno++) {

/* set all the s3c2410 internal irqs */

switch (irqno) {

/* deal with the special IRQs (cascaded) */

case IRQ_EINT4t7:

case IRQ_EINT8t23:

case IRQ_UART0:

case IRQ_UART1:

case IRQ_UART2:

case IRQ_ADCPARENT:

set_irq_chip(irqno, &s3c_irq_level_chip);

set_irq_handler(irqno, do_level_IRQ);

break;

case IRQ_RESERVED6:

case IRQ_RESERVED24:

/* no IRQ here */

break;

default:/*IRQ_WDT就是这条通路*/

//irqdbf("registering irq %d (s3c irq)/n", irqno);

set_irq_chip(irqno, &s3c_irq_chip); /*为中断号设置chip*/

set_irq_handler(irqno, do_edge_IRQ); /*设置中断例程*/

set_irq_flags(irqno, IRQF_VALID);/*设置中断ready的标记*/

}

}

/* setup the cascade irq handlers */

set_irq_chained_handler(IRQ_EINT4t7, s3c_irq_demux_extint);

set_irq_chained_handler(IRQ_EINT8t23, s3c_irq_demux_extint);

set_irq_chained_handler(IRQ_UART0, s3c_irq_demux_uart0);

set_irq_chained_handler(IRQ_UART1, s3c_irq_demux_uart1);

set_irq_chained_handler(IRQ_UART2, s3c_irq_demux_uart2);

set_irq_chained_handler(IRQ_ADCPARENT, s3c_irq_demux_adc);

/* external interrupts */

for (irqno = IRQ_EINT0; irqno <= IRQ_EINT3; irqno++) {

irqdbf("registering irq %d (ext int)/n", irqno);

set_irq_chip(irqno, &s3c_irq_eint0t4);

set_irq_handler(irqno, do_edge_IRQ);

set_irq_flags(irqno, IRQF_VALID);

}

for (irqno = IRQ_EINT4; irqno <= IRQ_EINT23; irqno++) {

irqdbf("registering irq %d (extended s3c irq)/n", irqno);

set_irq_chip(irqno, &s3c_irqext_chip);

set_irq_handler(irqno, do_edge_IRQ);

set_irq_flags(irqno, IRQF_VALID);

}

/* register the uart interrupts */

irqdbf("s3c2410: registering external interrupts/n");

for (irqno = IRQ_S3CUART_RX0; irqno <= IRQ_S3CUART_ERR0; irqno++) {

irqdbf("registering irq %d (s3c uart0 irq)/n", irqno);

set_irq_chip(irqno, &s3c_irq_uart0);

set_irq_handler(irqno, do_level_IRQ);

set_irq_flags(irqno, IRQF_VALID);

}

for (irqno = IRQ_S3CUART_RX1; irqno <= IRQ_S3CUART_ERR1; irqno++) {

irqdbf("registering irq %d (s3c uart1 irq)/n", irqno);

set_irq_chip(irqno, &s3c_irq_uart1);

set_irq_handler(irqno, do_level_IRQ);

set_irq_flags(irqno, IRQF_VALID);

}

for (irqno = IRQ_S3CUART_RX2; irqno <= IRQ_S3CUART_ERR2; irqno++) {

irqdbf("registering irq %d (s3c uart2 irq)/n", irqno);

set_irq_chip(irqno, &s3c_irq_uart2);

set_irq_handler(irqno, do_level_IRQ);

set_irq_flags(irqno, IRQF_VALID);

}

for (irqno = IRQ_TC; irqno <= IRQ_ADC; irqno++) {

irqdbf("registering irq %d (s3c adc irq)/n", irqno);

set_irq_chip(irqno, &s3c_irq_adc);

set_irq_handler(irqno, do_edge_IRQ);

set_irq_flags(irqno, IRQF_VALID);

}

irqdbf("s3c2410: registered interrupt handlers/n");

}

上面这个函数结合s3c2410的data sheet很好理解，就是注册各个必要的中断，注意这里为每个中断号注册的中断例程只是个整体的函数，该函数只是处理一些共性的操作如清中断标记位等，他会进一步调用我们注册的中断例程来处理特定的中断。如何注册中断会在后面分析。

这个初始化函数调用了很多与中断相关的函数，我们逐个分析：

先看set_irq_chip

kernel/irq/chip.c:

/

*set_irq_chip - set the irq chip for an irq

*@irq:irq number

*@chip:pointer to irq chip description structure

*/

/*为某个中断号设置一个chip*/

int set_irq_chip(unsigned int irq, struct irq_chip *chip)

{

struct irq_desc *desc;

unsigned long flags;

if (irq >= NR_IRQS) {

printk(KERN_ERR "Trying to install chip for IRQ%d/n", irq);

WARN_ON(1);

return -EINVAL;

}

if (!chip)

chip = &no_irq_chip;

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