linux中断处理体系结构
本人喜欢用代码+伪代码的方式写笔记。文中的花括号可能是方便记录而已。
如：
hw_get_module(LED_HARDWARE_MODULE_ID, (const hw_module_t**)&module)
{
问:怎么获得模块信息的?
答:hardware\libhardware\Hardware.c
...........
}
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作者email: dayhappyhappy@163.com
重要的数据结构
struct irq_desc {
irq_flow_handler_t handle_irq; /*当前中断处理函数入口*/
struct irq_chip *chip; /*底层的硬件访问*/
struct irqaction① *action; /*用户提供的中断处理函数链表 */
unsigned int status; /* IRQ status */
const char *name; /*中断名称*/
} ____cacheline_internodealigned_in_smp;
struct irqaction ①{
irq_handler_t handler; //中断处理函数
unsigned long flags; /*中断标志：是否共享中断，电平触发，边缘触发。。。*/
const char *name; /*/pro/interrupts 下显示*/
void *dev_id;
struct irqaction *next; /*链表 指向下一个*/
int irq; /*中断号*/
struct proc_dir_entry *dir;
irq_handler_t thread_fn;
struct task_struct *thread;
unsigned long thread_flags;
};
void __init start_kernel(void)//linux c语言入口
{
setup_arch(char **cmdline_p);
init_IRQ();
{
//初始化状态
for (irq = 0; irq < NR_IRQS; irq++)
irq_desc[irq].status |= IRQ_NOREQUEST | IRQ_NOPROBE;
init_arch_irq();
{
1.ask: 不同架构的处理器中断初始化函数是不一样的，该函数中怎么去处理?
1.answer: 在arch\arm\kernel\Setup.c中
struct machine_desc * mdesc = setup_machine(machine_arch_type);
init_arch_irq = mdesc->init_irq;
mdesc->init_irq在哪里定义？
架构相关: arch\arm\mach-s3c2440\mach-smdk2440.c
MACHINE_START(TCT_HAMMER, "TCT_HAMMER")
.phys_io = S3C2410_PA_UART,
.io_pg_offst = (((u32)S3C24XX_VA_UART) >> 18) & 0xfffc,
.boot_params = S3C2410_SDRAM_PA + 0x100,
.map_io = tct_hammer_map_io,
.init_irq = s3c24xx_init_irq,//★
.init_machine = tct_hammer_init,
.timer = &s3c24xx_timer,
MACHINE_END
2.ask: s3c24xx_init_irq 做了什么处理？
2.answer: arch\arm\plat-s3c24xx\Irq.c
for (irqno = IRQ_EINT4t7; irqno <= IRQ_ADCPARENT; irqno++) {
//(1)设置芯片
set_irq_chip(irqno, &s3c_irq_chip);
{
struct irq_desc *desc = irq_to_desc(irq);
desc->chip = chip;//填充chip
}
//(2)设置处理函数
set_irq_handler(irqno, handle_edge_irq);
{
__set_irq_handler(irq, handle, 0, NULL);
__set_irq_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
const char *name)
{
desc->handle_irq = handle; //处理函数
desc->name = name; //NULL
}
}
//(3)IRQF_VALID表示可以使用它们了
set_irq_flags(irqno, IRQF_VALID);
}
set_irq_chained_handler(IRQ_EINT4t7, s3c_irq_demux_extint4t7);
{
__set_irq_handler(irq, handle, 1, NULL);
}
set_irq_chained_handler(IRQ_EINT8t23, s3c_irq_demux_extint8);
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);
}
}
}
用户注册中断过程分析
include\linux\Interrupt.h
static inline int __must_check
request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
const char *name, void *dev)
{
return request_threaded_irq(irq, handler, NULL, flags, name, dev);
}
request_threaded_irq 分析
kernel\irq\Manage.c
/**
* request_threaded_irq - allocate an interrupt line
* @irq: Interrupt line to allocate
* @handler: Function to be called when the IRQ occurs.
* Primary handler for threaded interrupts
* If NULL and thread_fn != NULL the default
* primary handler is installed
* @thread_fn: Function called from the irq handler thread
* If NULL, no irq thread is created
* @irqflags: Interrupt type flags
* @devname: An ascii name for the claiming device
* @dev_id: A cookie passed back to the handler function
*/
int request_threaded_irq(unsigned int irq, irq_handler_t handler,
irq_handler_t thread_fn, unsigned long irqflags,
const char *devname, void *dev_id)
{
struct irqaction *action; //中断处理程序
struct irq_desc *desc; //中断描述数组
action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
action->handler = handler;//中断处理程序
action->thread_fn = thread_fn;
action->flags = irqflags;
action->name = devname;
action->dev_id = dev_id;
desc = irq_to_desc(irq);//获取到相应的中断描述
__setup_irq(irq, desc, action);
__setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
{
old_ptr = &desc->action;
old = *old_ptr;
do {
old_ptr = &old->next;
old = *old_ptr;
} while (old); //找到用户中断处理函数的最后一个
*old_ptr = new;
irq_chip_set_defaults(desc->chip);
//设置触发方式
__irq_set_trigger(desc, irq,new->flags & IRQF_TRIGGER_MASK);
new->irq = irq;
//启动中断
desc->chip->startup(irq);
}
}
当IRQ中断发生时：C语言入口函数asm_do_IRQ
void __exception asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
{
generic_handle_irq(irq);
{
generic_handle_irq_desc(irq, irq_to_desc(irq));
{
//irq 中断号 , irq_to_desc(irq)中断描述
desc->handle_irq(irq, desc);
1.ask 这是怎么处理的？
2.answer 例子： desc初始化的时候
set_irq_handler(irqno, handle_edge_irq); //执行的是handle_edge_irq
void handle_edge_irq(unsigned int irq, struct irq_desc *desc)
{
do {
struct irqaction *action = desc->action;
handle_IRQ_event(irq, action);
{
do {
//★ 逐个调用用户在action链表中注册的处理函数
ret = action->handler(irq, action->dev_id);
action = action->next;
}while (action);
}
}while ((desc->status & (IRQ_PENDING | IRQ_DISABLED)) == IRQ_PENDING);
}
}
}
struct irq_desc {
irq_flow_handler_t handle_irq; /*当前中断处理函数入口*/
struct irq_chip *chip; /*底层的硬件访问*/
struct irqaction① *action; /*用户提供的中断处理函数链表 */
unsigned int status; /* IRQ status */
const char *name; /*中断名称*/
} ____cacheline_internodealigned_in_smp;
struct irqaction ①{
irq_handler_t handler; //中断处理函数
unsigned long flags; /*中断标志：是否共享中断，电平触发，边缘触发。。。*/
const char *name; /*/pro/interrupts 下显示*/
void *dev_id;
struct irqaction *next; /*链表 指向下一个*/
int irq; /*中断号*/
struct proc_dir_entry *dir;
irq_handler_t thread_fn;
struct task_struct *thread;
unsigned long thread_flags;
};
void __init start_kernel(void)//linux c语言入口
{
setup_arch(char **cmdline_p);
init_IRQ();
{
//初始化状态
for (irq = 0; irq < NR_IRQS; irq++)
irq_desc[irq].status |= IRQ_NOREQUEST | IRQ_NOPROBE;
init_arch_irq();
{
1.ask: 不同架构的处理器中断初始化函数是不一样的，该函数中怎么去处理?
1.answer: 在arch\arm\kernel\Setup.c中
struct machine_desc * mdesc = setup_machine(machine_arch_type);
init_arch_irq = mdesc->init_irq;
mdesc->init_irq在哪里定义？
架构相关: arch\arm\mach-s3c2440\mach-smdk2440.c
MACHINE_START(TCT_HAMMER, "TCT_HAMMER")
.phys_io = S3C2410_PA_UART,
.io_pg_offst = (((u32)S3C24XX_VA_UART) >> 18) & 0xfffc,
.boot_params = S3C2410_SDRAM_PA + 0x100,
.map_io = tct_hammer_map_io,
.init_irq = s3c24xx_init_irq,//★
.init_machine = tct_hammer_init,
.timer = &s3c24xx_timer,
MACHINE_END
2.ask: s3c24xx_init_irq 做了什么处理？
2.answer: arch\arm\plat-s3c24xx\Irq.c
for (irqno = IRQ_EINT4t7; irqno <= IRQ_ADCPARENT; irqno++) {
//(1)设置芯片
set_irq_chip(irqno, &s3c_irq_chip);
{
struct irq_desc *desc = irq_to_desc(irq);
desc->chip = chip;//填充chip
}
//(2)设置处理函数
set_irq_handler(irqno, handle_edge_irq);
{
__set_irq_handler(irq, handle, 0, NULL);
__set_irq_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
const char *name)
{
desc->handle_irq = handle; //处理函数
desc->name = name; //NULL
}
}
//(3)IRQF_VALID表示可以使用它们了
set_irq_flags(irqno, IRQF_VALID);
}
set_irq_chained_handler(IRQ_EINT4t7, s3c_irq_demux_extint4t7);
{
__set_irq_handler(irq, handle, 1, NULL);
}
set_irq_chained_handler(IRQ_EINT8t23, s3c_irq_demux_extint8);
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);
}
}
}
用户注册中断过程分析
include\linux\Interrupt.h
static inline int __must_check
request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
const char *name, void *dev)
{
return request_threaded_irq(irq, handler, NULL, flags, name, dev);
}
request_threaded_irq 分析
kernel\irq\Manage.c
/**
* request_threaded_irq - allocate an interrupt line
* @irq: Interrupt line to allocate
* @handler: Function to be called when the IRQ occurs.
* Primary handler for threaded interrupts
* If NULL and thread_fn != NULL the default
* primary handler is installed
* @thread_fn: Function called from the irq handler thread
* If NULL, no irq thread is created
* @irqflags: Interrupt type flags
* @devname: An ascii name for the claiming device
* @dev_id: A cookie passed back to the handler function
*/
int request_threaded_irq(unsigned int irq, irq_handler_t handler,
irq_handler_t thread_fn, unsigned long irqflags,
const char *devname, void *dev_id)
{
struct irqaction *action; //中断处理程序
struct irq_desc *desc; //中断描述数组
action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
action->handler = handler;//中断处理程序
action->thread_fn = thread_fn;
action->flags = irqflags;
action->name = devname;
action->dev_id = dev_id;
desc = irq_to_desc(irq);//获取到相应的中断描述
__setup_irq(irq, desc, action);
__setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
{
old_ptr = &desc->action;
old = *old_ptr;
do {
old_ptr = &old->next;
old = *old_ptr;
} while (old); //找到用户中断处理函数的最后一个
*old_ptr = new;
irq_chip_set_defaults(desc->chip);
//设置触发方式
__irq_set_trigger(desc, irq,new->flags & IRQF_TRIGGER_MASK);
new->irq = irq;
//启动中断
desc->chip->startup(irq);
}
}
当IRQ中断发生时：C语言入口函数asm_do_IRQ
void __exception asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
{
generic_handle_irq(irq);
{
generic_handle_irq_desc(irq, irq_to_desc(irq));
{
//irq 中断号 , irq_to_desc(irq)中断描述
desc->handle_irq(irq, desc);
1.ask 这是怎么处理的？
2.answer 例子： desc初始化的时候
set_irq_handler(irqno, handle_edge_irq); //执行的是handle_edge_irq
void handle_edge_irq(unsigned int irq, struct irq_desc *desc)
{
do {
struct irqaction *action = desc->action;
handle_IRQ_event(irq, action);
{
do {
//★ 逐个调用用户在action链表中注册的处理函数
ret = action->handler(irq, action->dev_id);
action = action->next;
}while (action);
}
}while ((desc->status & (IRQ_PENDING | IRQ_DISABLED)) == IRQ_PENDING);
}
}
}
}
