分类： LINUX
2009-03-06 22:59:53
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今天讲一下s3c2410等arm开发板下linux中断相关的操作。
首先当然是进入start_kernel了，这里有中断初始化的函数
asmlinkage void
__init start_kernel(void)
{
………….
………….
init_IRQ();
……………..
……………
}
void __init init_IRQ(void)
{
struct irqdesc *desc;
extern void init_dma(void);
int irq;
#ifdef CONFIG_SMP
bad_irq_desc.affinity = CPU_MASK_ALL;
bad_irq_desc.cpu = smp_processor_id();
#endif
for (irq = 0, desc = irq_desc; irq < NR_IRQS; irq++, desc++) {
*desc = bad_irq_desc;
INIT_LIST_HEAD(&desc->pend);
}
//前面注册了哑铃中断
init_arch_irq();//注册具体开发板的中断。
init_dma();
}
init_arch_irq()这个函数又在哪里呢，它就是在这里
MACHINE_START(QQ2440, "QQ2440")
.phys_ram = S3C2410_SDRAM_PA,
.phys_io = S3C2410_PA_UART,
.io_pg_offst = (((u32)S3C24XX_VA_UART) >> 18) & 0xfffc,
.boot_params = S3C2410_SDRAM_PA + 0x100,
.init_irq =
sbc2440_init_irq,
.map_io = sbc2440_map_io,
.init_machine = sbc2440_init,
.timer = &s3c24xx_timer,
MACHINE_END
因此就调用具体开发板的中断初始函数。
sbc2440_init_irq然后调用s3c24xx_init_irq,我们知道中断在Linux以全局变量struct irqdesc irq_desc[NR_IRQS]管理;
struct irqdesc {
irq_handler_t handle;
struct irqchip *chip;
struct irqaction *action;
struct list_head pend;
void *chipdata;
void *data;
unsigned int disable_depth;
………….
…………
};
下面分析上面三个重要的成员
chip 它是具体中断的操作函数集，如屏蔽开启此中断，设置中断类型。
struct irqchip {
/*
* Acknowledge the IRQ.
* If this is a level-based IRQ, then it is expected to mask the IRQ
* as well.
*/
void (*ack)(unsigned int);
/*
* Mask the IRQ in hardware.
*/
void (*mask)(unsigned int);
/*
* Unmask the IRQ in hardware.
*/
void (*unmask)(unsigned int);
/*
* Ask the hardware to re-trigger the IRQ.
* Note: This method _must_ _not_ call the interrupt handler.
* If you are unable to retrigger the interrupt, do not
* provide a function, or if you do, return non-zero.
*/
int (*retrigger)(unsigned int);
/*
* Set the type of the IRQ.
*/
int (*type)(unsigned int, unsigned int);//设置中断类型是上升沿还是下降沿
/*
* Set wakeup-enable on the selected IRQ
*/
int (*wake)(unsigned int, unsigned int);
#ifdef CONFIG_SMP
/*
* Route an interrupt to a CPU
*/
void (*set_cpu)(struct irqdesc *desc, unsigned int irq, unsigned int cpu);
#endif
};
因此我们可以猜想s3c24xx_init_irq主要是给板子上相应中断赋具体值，事实上就是这样。
void __init s3c24xx_init_irq(void)
{
unsigned long pend;
unsigned long last;
int irqno;
int i;
irqdbf("s3c2410_init_irq: clearing interrupt status flags\n");
/*
first, clear all interrupts pending... */
last = 0;
for (i = 0; i < 4; i++) {
pend = __raw_readl(S3C2410_EINTPEND);
if (pend == 0 || pend == last)
break;
__raw_writel(pend, S3C2410_EINTPEND);
printk("irq: clearing pending ext status %08x\n", (int)pend);
last = pend;
}
last = 0;
for (i = 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 */
irqdbf("s3c2410_init_irq: registering s3c2410 interrupt handlers\n");
for (irqno = IRQ_BATT_FLT; irqno <= IRQ_ADCPARENT; irqno++) {
/* set all the s3c2410 internal irqs */
switch (irqno) {
/* deal with the special IRQs (cascaded) */
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:
//irqdbf("registering irq %d (s3c irq)\n", irqno);
set_irq_chip(irqno, &s3c_irq_chip);
set_irq_handler(irqno, do_edge_IRQ);
set_irq_flags(irqno, IRQF_VALID);
}
}
/* setup the cascade irq handlers */
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");
static struct irqchip s3c_irq_eint0t4 = {
.ack = s3c_irq_ack,
.mask = s3c_irq_mask,
.unmask = s3c_irq_unmask,
.wake = s3c_irq_wake,
.type = s3c_irqext_type,
};
static int s3c_irqext_type(unsigned int irq, unsigned int type)
{
void __iomem *extint_reg;
void __iomem *gpcon_reg;
unsigned long gpcon_offset, extint_offset;
unsigned long newvalue = 0, value;
if ((irq >= IRQ_EINT0) && (irq <= IRQ_EINT3))
{
gpcon_reg = S3C2410_GPFCON;
extint_reg = S3C2410_EXTINT0;
gpcon_offset = (irq - IRQ_EINT0) * 2;
extint_offset = (irq - IRQ_EINT0) * 4;
}
else if ((irq >= IRQ_EINT4) && (irq <= IRQ_EINT7))
{
gpcon_reg = S3C2410_GPFCON;
extint_reg = S3C2410_EXTINT0;
gpcon_offset = (irq - (EXTINT_OFF)) * 2;
extint_offset = (irq - (EXTINT_OFF)) * 4;
}
else if ((irq >= IRQ_EINT8) && (irq <= IRQ_EINT15))
{
gpcon_reg = S3C2410_GPGCON;
extint_reg = S3C2410_EXTINT1;
gpcon_offset = (irq - IRQ_EINT8) * 2;
extint_offset = (irq - IRQ_EINT8) * 4;
}
else if ((irq >= IRQ_EINT16) && (irq <= IRQ_EINT23))
{
gpcon_reg = S3C2410_GPGCON;
extint_reg = S3C2410_EXTINT2;
gpcon_offset = (irq - IRQ_EINT8) * 2;
extint_offset = (irq - IRQ_EINT16) * 4;
} else
return -1;
/* Set the GPIO to external interrupt mode */
value = __raw_readl(gpcon_reg);
value = (value & ~(3 << gpcon_offset)) | (0x02 << gpcon_offset);
__raw_writel(value, gpcon_reg);
/* Set the external interrupt to pointed trigger type */
switch (type)
{
case IRQT_NOEDGE:
printk(KERN_WARNING "No edge setting!\n");
break;
case IRQT_RISING:
newvalue = S3C2410_EXTINT_RISEEDGE;
break;
case IRQT_FALLING:
newvalue = S3C2410_EXTINT_FALLEDGE;
break;
case IRQT_BOTHEDGE:
newvalue = S3C2410_EXTINT_BOTHEDGE;
break;
case IRQT_LOW:
newvalue = S3C2410_EXTINT_LOWLEV;
break;
case IRQT_HIGH:
newvalue = S3C2410_EXTINT_HILEV;
break;
default:
printk(KERN_ERR "No such irq type %d", type);
return -1;
}
value = __raw_readl(extint_reg);
value = (value & ~(7 << extint_offset)) | (newvalue << extint_offset);
__raw_writel(value, extint_reg);
return 0;
}
当中断初始化后我们在驱动中要使用中断时，就可以通过request_irq()申请，并且通过set_irq_type设置中断的类型，这个其实是调用具体中断的irq_chip->type函数设置的。
