按键驱动分析：
#include <linux/module.h> #include <linux/kernel.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/delay.h> #include <linux/poll.h> #include <linux/irq.h> #include <asm/irq.h> #include <linux/wait.h> #include <linux/sched.h> #include <linux/interrupt.h> #include <asm/uaccess.h> #include <linux/gpio.h> #include <mach/regs-gpio.h> #include <mach/hardware.h> #include <linux/platform_device.h> #include <linux/cdev.h> #include <linux/miscdevice.h> #include <linux/miscdevice.h> //#include <linux/time.h> #include <linux/device.h> struct class *key_class;//udev机制自动创建文件结点 #define USING_TASKLET //struct timespec start_time; //struct timespec end_time; static int key_major = 0; struct key_irq_desc { // unsigned int irq;//对拥鼻暗膇 irq 号 int pin; //对应的管脚 int pin_setting;//将邋邋GPIO口设置为外部中断源 int number; char *name; }; /* 用来指定按键所用的外部中断引脚及中断触发方式, 名字 */ static struct key_irq_desc key_irqs [] = { {S5PV210_GPH0(3), S3C_GPIO_SFN(0xf), 0, "KEY1"}, /* K1 */ {S5PV210_GPH0(4), S3C_GPIO_SFN(0xf), 1, "KEY2"}, /* K2 */ {S5PV210_GPH0(5), S3C_GPIO_SFN(0xf), 2, "KEY3"}, /* K3 */ {S5PV210_GPH0(6), S3C_GPIO_SFN(0xf), 3, "KEY4"}, /* K4 */ {S5PV210_GPH0(7), S3C_GPIO_SFN(0xf), 4, "KEY5"}, /* K5 */ }; /* 按键被按下的次数(准确地说，是发生中断的次数) */ static volatile int key_values[] = {0, 0, 0, 0, 0}; /* 等待队列: * 当没有按键被按下时，如果有进程调用key_read函数， * 它将休眠 */ static DECLARE_WAIT_QUEUE_HEAD(key_waitq); //初始化一个等待队列头key_waitq /* 中断事件标志, 中断服务程序将它置1，key_read将它清0 */ static volatile int ev_press = 0;//按下为1，抬起为0 #ifdef USING_TASKLET static struct tasklet_struct key_tasklet; static void key_do_tasklet(unsigned long); //DECLARE_TASKLET(key_tasklet, key_do_tasklet, 0);//在init中初始化 static void key_do_tasklet(unsigned long data) { printk("key_do_tasklet\n"); } #endif static irqreturn_t key_interrupt(int irq, void *dev_id) { printk("in the key_interrupt before wake_up!!\n"); // clock_gettime(CLOCK_REALTIME, &start_time); // printk("%d\n%d\n",start_time.tvsec,start_time.tv_nsec); struct key_irq_desc *key_irqs = (struct key_irq_desc *)dev_id;//see at request_irq int up = gpio_get_value(key_irqs->pin); printk("<1>up=%d\n",up); if (up) key_values[key_irqs->number] = (key_irqs->number + 1) + 0x80; else key_values[key_irqs->number] += 1; ev_press = 1; /* 表示中断发生了 */ wake_up_interruptible(&key_waitq); /* 唤醒休眠的进程 */ printk("in the key_interrupt after wake_up!!\n"); #ifdef USING_TASKLET tasklet_schedule(&key_tasklet);//调度key_do_tasklet #endif return IRQ_RETVAL(IRQ_HANDLED); // clock_gettime(CLOCK_REALTIME, &end_time); // printf("%d\n%d\n",end_time.tvsec,end_time.tv_nsec); } /* 应用程序对设备文件/dev/key执行open(...)时， * 就会调用key_open函数 */ static int key_open(struct inode *inode, struct file *file) { printk("in the key_open!\n"); int i; int err; int irq; for (i = 0; i < sizeof(key_irqs)/sizeof(key_irqs[0]); i++) { // 注册中断处理函数 s3c_gpio_cfgpin(key_irqs[i].pin,key_irqs[i].pin_setting);//配置邋邋GPIO口 irq=gpio_to_irq(key_irqs[i].pin); err = request_irq(irq, key_interrupt, IRQ_TYPE_EDGE_BOTH, key_irqs[i].name, (void *)&key_irqs[i]);// 设备ID号 //set_irq_type(key_irqs[i].irq, IRQ_TYPE_EDGE_FALLING);//<linux/irq.h> 下降沿触发 // IRQ_TYPE_EDGE_RISING, IRQ_TYPE_EDGE_BOTH, IRQ_TYPE_EDGE_HIGH, // IRQ_TYPE_EDGE_LOW if (err) break; } if (err) { // 释放已经注册的中断 i--; for (; i >= 0; i--) { irq=gpio_to_irq(key_irqs[i].pin); disable_irq(irq); free_irq(irq, (void *)&key_irqs[i]); } return -EBUSY; } return 0; } /* 应用程序对设备文件/dev/key执行close(...)时， * 就会调用key_close函数 */ static int key_close(struct inode *inode, struct file *file) { int i; int irq; for (i = 0; i < sizeof(key_irqs)/sizeof(key_irqs[0]); i++) { irq=gpio_to_irq(key_irqs[i].pin); // 释放已经注册的中断 disable_irq(irq); free_irq(irq, (void *)&key_irqs[i]); //释放gpio口 gpio_free(key_irqs[i].pin); } return 0; } /* 应用程序对设备文件/dev/key执行read(...)时， * 就会调用key_read函数 */ static int key_read(struct file *filp, char __user *buff, size_t count, loff_t *offp) { printk("in the key_read before wait_event!!\n"); unsigned long err; if (!ev_press) { if (filp->f_flags & O_NONBLOCK) return -EAGAIN;//如果是阻塞访问则直接返回 else { /* 如果ev_press等于0，休眠,直到key_waitq被唤醒,并且ev_press为真*/ wait_event_interruptible(key_waitq, ev_press); printk("(1)in the key_read after wait_event!!\n"); } } printk("(2)in the key_read after wait_event!!\n"); /* 执行到这里时，ev_press等于1，将它清0 */ ev_press = 0; /* 将按键状态复制给用户，并清0 */ //copy_to_user(void __user * to,const void * from,unsigned long n) err = copy_to_user(buff, (const void *)key_values, min(sizeof(key_values), count)); memset((void *)key_values, 0, sizeof(key_values));//清零 return err ? -EFAULT : min(sizeof(key_values), count); } /************************************************** * 当用户程序调用select函数时，本函数被调用 * 如果有按键数据，则select函数会立刻返回 * 如果没有按键数据，本函数使用poll_wait等待 **************************************************/ static unsigned int key_poll(struct file *file, struct poll_table_struct *wait) { printk("in the key_poll!!\n"); unsigned int mask = 0; poll_wait(file, &key_waitq, wait);//将等待队列添加到poll_table if (ev_press) mask |= POLLIN | POLLRDNORM;/*数据可获得*/ return mask;//mask=0;休眠timeout } /* 这个结构是字符设备驱动程序的核心 * 当应用程序操作设备文件时所调用的open、read、write等函数， * 最终会调用这个结构中的对应函数 */ static struct file_operations key_fops = { .owner = THIS_MODULE, /* 这是一个宏，指向编译模块时自动创建的__this_module变量 */ .open = key_open, .release = key_close, .read = key_read, .poll = key_poll, }; /* * Set up the cdev structure for a device. */ static void key_setup_cdev(struct cdev *dev, int minor, struct file_operations *fops) { int err, devno = MKDEV(key_major, minor); cdev_init(dev, fops); dev->owner = THIS_MODULE; dev->ops = fops; err = cdev_add (dev, devno, 1); /* Fail gracefully if need be */ if (err) printk (KERN_NOTICE "Error %d adding key%d", err, minor); } /* * We export one key device. There's no need for us to maintain any * special housekeeping info, so we just deal with raw cdev. */ static struct cdev key_cdev; /* * 执行"insmod key_drv.ko" 命令时就会调用这个函数 */ static int __init userkey_init(void) //static int key_init(void) { int result; dev_t dev = MKDEV(key_major, 0); char dev_name[]="key"; /*request gpio*/ int ret; int i=0; for(i=0;i<5;i++) { ret = gpio_request(key_irqs[i].pin, "KEY"); if (ret) { printk("%s:request GPIO %d for KEY failed,ret= %d\n",dev_name,key_irqs[i],ret); } } /* Figure out our device number. */ if (key_major) result = register_chrdev_region(dev, 1, dev_name); else { result = alloc_chrdev_region(&dev, 0, 1, dev_name); key_major = MAJOR(dev); } if (result < 0) { printk(KERN_WARNING "key: unable to get major %d\n", key_major); return result; } if (key_major == 0) key_major = result; #ifdef USING_TASKLET tasklet_init(&key_tasklet, key_do_tasklet, 0);//初始化底半部机制tasklet #endif /* Now set up cdev. */ key_setup_cdev(&key_cdev, 0, &key_fops); /*udev自动创建文件结点*/ key_class = class_create(THIS_MODULE, "key_class"); device_create(key_class, NULL, dev, NULL,dev_name); printk("key device installed, with major %d\n", key_major); printk("The device name is: /dev/%s\n", dev_name); return 0; } /* * 执行rmod key_drv”命令时就会调用这个函数 */ static void __exit userkey_exit(void) { device_destroy(key_class, key_cdev.dev); class_destroy(key_class); cdev_del(&key_cdev); unregister_chrdev_region(MKDEV(key_major, 0), 1); #ifdef USING_TASKLET tasklet_kill(&key_tasklet); #endif printk("key device uninstalled\n"); } /* 这两行指定驱动程序的初始化函数和卸载函数 */ module_init(userkey_init); module_exit(userkey_exit); /* 描述驱动程序的一些信息，不是必须的 */ MODULE_AUTHOR("mhb@SEU"); // 驱动程序的作者 MODULE_DESCRIPTION("KEY Driver"); // 一些描述信息 MODULE_LICENSE("Dual BSD/GPL"); // 遵循的协议
测试实例代码：
#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/ioctl.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <sys/select.h> #include <sys/time.h> #include <errno.h> int main(void) { int i; int key_fd; int key_value[]={0,0,0,0,0}; /*打开键盘设备文件*/ key_fd = open("/dev/key", 0); printf("key_fd=%d!!\n",key_fd); if (key_fd < 0) { perror("open device key"); exit(1); } for (;;) { fd_set rds; int ret; FD_ZERO(&rds); FD_SET(key_fd, &rds); /*使用系统调用select检查是否能够从/dev/key设备读取数据*/ ret = select(key_fd + 1, &rds, NULL, NULL, NULL); /*读取出错则退出程序*/ if (ret < 0) { perror("select"); exit(1); } if (ret == 0) { printf("Timeout.\n"); } /*能够读取到数据*/ else if (FD_ISSET(key_fd, &rds)) { /*开始读取键盘驱动发出的数据，注意key_value和键盘驱动中定义为一致的类型*/ int ret = read(key_fd, key_value, sizeof key_value); if (ret != sizeof key_value) { if (errno != EAGAIN) perror("read key\n"); continue; } else { /*打印键值*/ for (i = 0; i < 5; i++) printf("K%d %s, key value = 0x%02x\n", \ i+1, (key_value[i] & 0x80) ? "released": \ key_value[i] ? "pressed down" : "", key_value[i]); key_value[i] = 0; } } } /*关闭设备文件句柄*/ close(key_fd); return 0; }
输出：
/*output [root@FORLINX210]# insmod int_key_drv.ko [ 27.114321] key device installed, with major 247 [ 27.118175] The device name is: /dev/key [root@FORLINX210]# ./key_test [ 30.396897] in the key_open! [ 30.398527] in the key_poll!! key_fd=3!! [ 33.959336] in the key_interrupt before wake_up!! [ 33.962558] up=0 [ 33.964379] in the key_interrupt after wake_up!! [ 33.968974] key_do_tasklet [ 33.971669] in the key_poll!! [ 33.974631] in the key_read before wait_event!! [ 33.979124] (2)in the key_read after wait_event!! [ 33.983897] in the key_poll!! K1 pressed down, key value = 0x01 K2 , key value = 0x00 K3 , key value = 0x00 K4 , key value = 0x00 K5 , key value = 0x00 [ 37.173298] in the key_interrupt before wake_up!! [ 37.176516] up=1 [ 37.178338] in the key_interrupt after wake_up!! [ 37.182932] key_do_tasklet [ 37.185625] in the key_poll!! [ 37.188582] in the key_read before wait_event!! [ 37.193085] (2)in the key_read after wait_event!! [ 37.197830] in the key_poll!! K1 released, key value = 0x81 K2 , key value = 0x00 K3 , key value = 0x00 K4 , key value = 0x00 K5 , key value = 0x00 [ 42.013178] in the key_interrupt before wake_up!! [ 42.016393] up=0 [ 42.018213] in the key_interrupt after wake_up!! [ 42.022808] key_do_tasklet [ 42.025501] in the key_poll!! [ 42.028457] in the key_read before wait_event!! [ 42.032961] (2)in the key_read after wait_event!! [ 42.037702] in the key_poll!! K1 , key value = 0x00 K2 pressed down, key value = 0x01 K3 , key value = 0x00 K4 , key value = 0x00 K5 , key value = 0x00 [ 51.785335] in the key_interrupt before wake_up!! [ 51.788557] up=1 [ 51.790377] in the key_interrupt after wake_up!! [ 51.794971] key_do_tasklet [ 51.797664] in the key_poll!! [ 51.800603] in the key_read before wait_event!! [ 51.805127] (2)in the key_read after wait_event!! [ 51.809867] in the key_poll!! K1 , key value = 0x00 K2 released, key value = 0x82 K3 , key value = 0x00 K4 , key value = 0x00 K5 , key value = 0x00 */