专题1-按键驱动程序设计-第3课-按键驱动硬件操作实现

1、回顾裸机玩中断写的程序

底下这个程序主要就是把GPIO的功能设置为中断功能，这样当中断发生了就通过读该寄存器的值判断。

#define GPFCON  (volatile unsigned long *)0x56000050
/*
 * K1,K2,K3,K4对应GPF1、GPF4、GPF2、GPF0
 */
#define GPF0_int     (0x2<<(0*2))
#define GPF1_int     (0x2<<(1*2))
#define GPF2_int     (0x2<<(2*2))
#define GPF4_int     (0x2<<(4*2))

#define GPF0_msk    (3<<(0*2))
#define GPF1_msk    (3<<(1*2))
#define GPF2_msk    (3<<(2*2))
#define GPF4_msk    (3<<(4*2))

void button_init()
{   
    *(GPFCON) &= ~(GPF0_msk | GPF1_msk | GPF2_msk | GPF4_msk);
    *(GPFCON) |= GPF0_int | GPF1_int | GPF2_int | GPF4_int;
}

 

 

2、按键中断程序

#include <linux/module.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/interrupt.h>
#include <linux/fs.h>
#include <linux/io.h>

#define GPFCON 0x56000050

irqreturn_t key_int(int irq, void *dev_id)
{
    //1. 检测是否发生了按键中断

    //2. 清除已经发生的按键中断

    //3. 打印按键值
    printk("key down!\n");
    
    return 0;
        
}

void key_hw_init()//设置GPIO引脚功能
{
    unsigned short data; 
    unsigned int *gpio_config;
    
    gpio_config = ioremap(GPFCON,4);
    data = readw(gpio_config);//读一个32位的寄存器
    data &= ~0b11;
    data |= 0b10;
    writew(data,gpio_config);//写32位到该寄存器
}

int key_open(struct inode *node,struct file *filp)
{
    return 0;
}

struct file_operations key_fops = 
{
    .open = key_open,
};

struct miscdevice key_miscdev = {
    .minor = 200,
    .name = "tq2440key",
    .fops = &key_fops,
};

static int button_init()
{
    misc_register(&key_miscdev);
    
    //按键硬件初始化
    key_hw_init();
    
    //注册中断处理程序，按下的时候产生中断，如何查找中断号呢？？？
    request_irq(IRQ_EINT0,key_int,IRQF_TRIGGER_FALLING,"tq2440key",0);
    
    return 0;
}

static void button_exit()
{
    misc_deregister(&key_miscdev);  
}


module_init(button_init);
module_exit(button_exit);

makefile

obj-m := key.o
KDIR := /home/S5-driver/lesson7/linux-tq2440/
all:
    make -C $(KDIR) M=$(PWD) modules CROSS_COMPILE=arm-linux- ARCH=arm
clean:
    rm -f *.ko *.o *.mod.o *.mod.c *.symvers *.bak *.order