九、【interrupt】按键中断

一、linux内核中中断的使用

1、申请中断

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1	static inline int __must_check request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,const char *name, void *dev)

参数：

• irq: 中断号
• handler:中断处理程序
• flags:中断标志，

对应外部中断，flags表示中断触发的方式：

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#define IRQF_TRIGGER_NONE   0x00000000 #define IRQF_TRIGGER_RISING 0x00000001 #define IRQF_TRIGGER_FALLING    0x00000002 #define IRQF_TRIGGER_HIGH   0x00000004 #define IRQF_TRIGGER_LOW    0x00000008

对于其他一般中断，flags用于设置中断的处理方式：

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#define IRQF_DISABLED       0x00000020 #define IRQF_SAMPLE_RANDOM  0x00000040 #define IRQF_SHARED     0x00000080

• name:自定义的中断名。
• dev:传递给中断处理程序的实参。

返回值：

　　成功返回0，否则返回负值。

2、中断处理程序

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1	irqreturn_t xxx_handler(int irq, void * dev

参数：

• irq：中断号。
• dev:中断申请函数传过来的参数。

返回值：

　　返回值为以下三个枚举值，IR_HANDLED表示中断被正确处理了

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enum irqreturn { 　　IRQ_NONE = (0 << 0), 　　IRQ_HANDLED = (1 << 0), 　　IRQ_WAKE_THREAD = (1 << 1), };

3、中断注销

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1	void free_irq(unsigned int irq, void *dev_id)

参数：

• irq:中断号。
• dev_id:中断的结构体

 

二、查看中断

 

三、中断号

中断号其实就是一个整数，该整数是内核给每个中断源的唯一编号。

6818主板的中断号定义在s5p6818_irq.h中

1、外部中断号

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#define IRQ_GPIO_A_START        (IRQ_GPIO_START + PAD_GPIO_A) #define IRQ_GPIO_B_START        (IRQ_GPIO_START + PAD_GPIO_B) #define IRQ_GPIO_C_START        (IRQ_GPIO_START + PAD_GPIO_C) #define IRQ_GPIO_D_START        (IRQ_GPIO_START + PAD_GPIO_D) #define IRQ_GPIO_E_START        (IRQ_GPIO_START + PAD_GPIO_E)

2、其他一般中断的中断号

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#define IRQ_PHY_MCUSTOP                 (0  + 32) #define IRQ_PHY_DMA0                    (1  + 32) #define IRQ_PHY_DMA1                    (2  + 32) #define IRQ_PHY_CLKPWR_INTREQPWR        (3  + 32) #define IRQ_PHY_CLKPWR_ALIVEIRQ         (4  + 32) #define IRQ_PHY_CLKPWR_RTCIRQ           (5  + 32) #define IRQ_PHY_UART1                   (6  + 32) // pl01115_Uart_modem #define IRQ_PHY_UART0                   (7  + 32) // UART0_MODULE #define IRQ_PHY_UART2                   (8  + 32) // UART1_MODULE #define IRQ_PHY_UART3                   (9  + 32) // pl01115_Uart_nodma0 #define IRQ_PHY_UART4                   (10 + 32)   // pl01115_Uart_nodma1 #define IRQ_PHY_UART5                   (11 + 32)   // pl01115_Uart_nodma2 #define IRQ_PHY_SSP0                    (12 + 32) #define IRQ_PHY_SSP1                    (13 + 32) #define IRQ_PHY_SSP2                    (14 + 32) #define IRQ_PHY_I2C0                    (15 + 32) #define IRQ_PHY_I2C1                    (16 + 32) #define IRQ_PHY_I2C2                    (17 + 32) #define IRQ_PHY_DEINTERLACE             (18 + 32) #define IRQ_PHY_SCALER                  (19 + 32) #define IRQ_PHY_AC97                    (20 + 32) #define IRQ_PHY_SPDIFRX                 (21 + 32) #define IRQ_PHY_SPDIFTX                 (22 + 32) #define IRQ_PHY_TIMER_INT0              (23 + 32) #define IRQ_PHY_TIMER_INT1              (24 + 32) #define IRQ_PHY_TIMER_INT2              (25 + 32) #define IRQ_PHY_TIMER_INT3              (26 + 32) #define IRQ_PHY_PWM_INT0                (27 + 32) #define IRQ_PHY_PWM_INT1                (28 + 32) #define IRQ_PHY_PWM_INT2                (29 + 32) #define IRQ_PHY_PWM_INT3                (30 + 32) #define IRQ_PHY_WDT                     (31 + 32) #define IRQ_PHY_MPEGTSI                 (32 + 32) #define IRQ_PHY_DPC_P                   (33 + 32) #define IRQ_PHY_DPC_S                   (34 + 32) #define IRQ_PHY_RESCONV                 (35 + 32) #define IRQ_PHY_HDMI                    (36 + 32) #define IRQ_PHY_VIP0                    (37 + 32) #define IRQ_PHY_VIP1                    (38 + 32) #define IRQ_PHY_MIPI                    (39 + 32) #define IRQ_PHY_VR                      (40 + 32) #define IRQ_PHY_ADC                     (41 + 32) #define IRQ_PHY_PPM                     (42 + 32) #define IRQ_PHY_SDMMC0                  (43 + 32) #define IRQ_PHY_SDMMC1                  (44 + 32) #define IRQ_PHY_SDMMC2                  (45 + 32) #define IRQ_PHY_CODA960_HOST            (46 + 32) #define IRQ_PHY_CODA960_JPG             (47 + 32) #define IRQ_PHY_GMAC                    (48 + 32) #define IRQ_PHY_USB20OTG                (49 + 32) #define IRQ_PHY_USB20HOST               (50 + 32) #define IRQ_PHY_CAN0                    (51 + 32) #define IRQ_PHY_CAN1                    (52 + 32) #define IRQ_PHY_GPIOA                   (53 + 32) #define IRQ_PHY_GPIOB                   (54 + 32) #define IRQ_PHY_GPIOC                   (55 + 32) #define IRQ_PHY_GPIOD                   (56 + 32) #define IRQ_PHY_GPIOE                   (57 + 32) #define IRQ_PHY_CRYPTO                  (58 + 32) #define IRQ_PHY_PDM                     (59 + 32) #define IRQ_PHY_TMU0                    (60 + 32) #define IRQ_PHY_TMU1                    (61 + 32) #define IRQ_PHY_VIP2                    (72 + 32)

3、三个中断共用一个中断处理程序

如何区分是哪个中断发生导致中断处理程序被内核调用的？
（1）通过中断号----某个中断发生，该中断的中断号会传递给中断处理程序的第一个形参
（2）通过注册时，传递给中断处理程序不同 (void * dev)

4、中断处理程序是一个原子过程

中断处理过程是原子的，不能在中断处理程序中使用可能导致阻塞的函数，例如：

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1	ssleep 、copy_to_user/copy_from_user、获取信号量..

不然会导致如下错误：

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[   39.085000] Exception stack(0xc0a93f58 to 0xc0a93fa0) [   39.085000] 3f40:                                                       ffffffed 00000000 [   39.085000] 3f60: 00000000 00000000 c0a92000 c0b2c248 c0738290 c0a92000 c0a92000 c0ab0128 [   39.085000] 3f80: 00000000 00000000 00000019 c0a93fa0 c000f83c c000f840 600d0013 ffffffff [   39.085000] [<c000e840>] (__irq_svc+0x40/0x70) from [<c000f840>] (default_idle+0x2c/0x30) [   39.085000] [<c000f840>] (default_idle+0x2c/0x30) from [<c000fb90>] (cpu_idle+0xd8/0x104) [   39.085000] [<c000fb90>] (cpu_idle+0xd8/0x104) from [<c0a5483c>] (start_kernel+0x328/0x334) [   39.085000] ---[ end trace 340d61c57173f93b ]--- [   39.085000] BUG: scheduling while atomic: swapper/0/0/0x00010002---------在原子过程中启动了调度器

内核中提供的延时函数：以下的函数是忙等延时，不会休眠。ssleep是休眠延时，我们中断处理程序中不能使用忙等延时。

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1 2	udelay() ndelay()

 

四、按键驱动程序

key_drv.c

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#include <linux/init.h> #include <linux/module.h> #include <linux/kernel.h> #include <linux/cdev.h> #include <linux/fs.h> #include <linux/device.h> #include <linux/ioport.h> #include <linux/io.h> #include <linux/uaccess.h> #include <linux/types.h> #include <linux/gpio.h> #include <cfg_type.h> #include <linux/interrupt.h> #include <linux/miscdevice.h> #include <linux/delay.h> struct key_gpio_t{     unsigned int irq;     char irqname[20];     unsigned char keyvalue; };     static struct key_gpio_t key_gpio[]= {     {IRQ_GPIO_A_START+28,"KEY2_GPIOA28",2},     {IRQ_GPIO_B_START+30,"KEY3_GPIOB30",3},     {IRQ_GPIO_B_START+31,"KEY4_GPIOB31",4},     {IRQ_GPIO_B_START+9,  "KEY6_GPIOB9",6}, }; static char keyvalue = 0; ssize_t key_read(struct file *filp, char __user * buf, size_t size, loff_t *oft) {                 int ret;       if(size !=1)       {         return -EINVAL;       }       ret = copy_to_user(buf, &keyvalue, sizeof(keyvalue));       if(ret != 0)       {         return (size -ret);       }       keyvalue=0;       return size; } static irqreturn_t key_handler(int irq, void * dev) {           struct key_gpio_t keytmp=*(struct key_gpio_t *)dev;     keyvalue =keytmp.keyvalue;     mdelay(500);  //按键防抖     return IRQ_HANDLED; }     struct file_operations key_misc_fops= {     .read = key_read, }; static struct miscdevice key_misc={     .minor = MISC_DYNAMIC_MINOR,     .name = "key_misc",     .fops =  &key_misc_fops,     }; static int __init  key_init(void) {       int ret,i;        printk(KERN_INFO"key_init\n");       ret = misc_register(&key_misc);       if(ret < 0)       {             printk(KERN_INFO"key misc register fail.\n");         goto misc_register_err;       }     for(i=0;i<4;i++)     {          ret = request_irq(key_gpio[i].irq, key_handler,IRQF_TRIGGER_FALLING,key_gpio[i].irqname,(void*)&key_gpio[i]);          if(ret < 0)          {             printk(KERN_INFO"request_irq fail.\n");             goto irq_request_err;          }     }     return 0;   irq_request_err:     while(i--)     {         free_irq(key_gpio[i].irq,NULL);     } misc_register_err:         return 0; }   static void __exit key_exit(void) {     int i;     printk(KERN_INFO"key_exit\n");     misc_deregister(&key_misc);         for(i=0;i<4;i++)      {         free_irq(key_gpio[i].irq,(void *)&key_gpio[i]);      }     }   module_init(key_init); module_exit(key_exit); MODULE_LICENSE("GPL");

　　

 

main.c

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#include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> #include <stdio.h> #include <sys/ioctl.h>     int main() {     int fd,ret;       char keyvalue=0;     fd = open("/dev/key_misc",O_RDWR);     if(fd<0)     {         perror("open key_misc error!");            }     while(1)     {         ret=read(fd,&keyvalue,1);         if(ret !=1)         {             perror("read error");             continue;         }         if(keyvalue!=0)         {              printf("keyvalue=%d\n",keyvalue);         }     }            close(fd); }

　　

 相关链接：

　　　　Linux设备树语法详解-中断