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本节实验目标实现按键触发中断终端显示按键松开或按下

实验平台 芯灵思Sinlinx A33 开发板

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step1 查看原理图，三个按键都连接到LRADC0引脚，通过判断电压大小来确定是按的哪个键。

step2 内核关于 CPU 的中断号linux 中断注册函数中的 irq 中断号并不是芯片物理上的编号，而是由芯片商在移植 Linux 系统时定在构架相

关的头文件中定义好的， 在内核源码中，名字一般是 irqs.h。

      打开vim /root/work/sinlinx/a33/lichee/linux-3.4/arch/arm/mach-sunxi/include/mach/irqs.h

这里全志A33 是#include "sun8i/irqs-sun8iw5p1.h"

打开vim /root/work/sinlinx/a33/lichee/linux-3.4/arch/arm/mach-sunxi/include/mach/sun8i/irqs-sun8iw5p1.h 

不知道开发板用的哪个平台，直接在.config中找

由此找到芯片在内核中的中断号

step 3  简要介绍中断驱动要用到的函数

查看 irq.h 文件  里面有关于中断的函数结构体声明 /root/work/sinlinx/a33/lichee/linux-3.4/include/linux/irq.h 

/**

 * struct irq_data - per irq and irq chip data passed down to chip functions

 * @irq:                interrupt number

 * @hwirq:              hardware interrupt number, local to the interrupt domain

 * @node:               node index useful for balancing

 * @state_use_accessors: status information for irq chip functions.

 *                      Use accessor functions to deal with it

 * @chip:               low level interrupt hardware access

 * @domain:             Interrupt translation domain; responsible for mapping

 *                      between hwirq number and linux irq number.

 * @handler_data:       per-IRQ data for the irq_chip methods

 * @chip_data:          platform-specific per-chip private data for the chip

 *                      methods, to allow shared chip implementations

 * @msi_desc:           MSI descriptor

 * @affinity:           IRQ affinity on SMP

 *

 * The fields here need to overlay the ones in irq_desc until we

 * cleaned up the direct references and switched everything over to

 * irq_data.

 */

struct irq_data {

        unsigned int            irq;

        unsigned long           hwirq;

        unsigned int            node;

        unsigned int            state_use_accessors;

        struct irq_chip         *chip;

        struct irq_domain       *domain;

        void                    *handler_data;

        void                    *chip_data;

        struct msi_desc         *msi_desc;

#ifdef CONFIG_SMP

        cpumask_var_t           affinity;

#endif

};

struct irqaction 结构体在 /root/work/sinlinx/a33/lichee/linux-3.4/include/linux/interrupt.h 

/**

 * struct irqaction - per interrupt action descriptor

 * @handler:    interrupt handler function

 * @flags:      flags (see IRQF_* above)

 * @name:       name of the device

 * @dev_id:     cookie to identify the device

 * @percpu_dev_id:      cookie to identify the device

 * @next:       pointer to the next irqaction for shared interrupts

 * @irq:        interrupt number

 * @dir:        pointer to the proc/irq/NN/name entry

 * @thread_fn:  interrupt handler function for threaded interrupts

 * @thread:     thread pointer for threaded interrupts

 * @thread_flags:       flags related to @thread

 * @thread_mask:        bitmask for keeping track of @thread activity

 */

struct irqaction {

        irq_handler_t           handler;      中断服务函数 handler

        unsigned long           flags;

        void                    *dev_id;

        void __percpu           *percpu_dev_id;

        struct irqaction        *next;

        int                     irq;

        irq_handler_t           thread_fn;

        struct task_struct      *thread;

        unsigned long           thread_flags;

        unsigned long           thread_mask;

        const char              *name;

        struct proc_dir_entry   *dir;

} ____cacheline_internodealigned_in_smp;

共享中断是指多个设备共享一根中断线的情况， 在中断到来时，会遍历共享此中断的所有中断处理程序， 直

到某一个中断服务函数时返回 IRQ_HANDLED。