按键驱动程序防止抖动的源代码

#include <linux/module.h> #include <linux/kernel.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/delay.h> #include <linux/device.h> #include <linux/kdev_t.h> #include <linux/interrupt.h> #include <linux/irqreturn.h> #include <linux/irqflags.h> #include <linux/irq.h> #include <asm/arch/regs-irq.h> #include <asm/arch/regs-gpio.h> #include <linux/wait.h> #include <linux/poll.h> #include <asm/uaccess.h> #include <asm/hardware.h> #include <asm/io.h> #include <asm/plat-s3c24xx/irq.h> /* GPIO引脚地址 */ #define S3C2440_GPFCON 0x56000050 #define S3C2440_GPGCON 0x56000060 #define DEVICE_NAME "s3c2440_buttons_poll" static unsigned int major; static struct class *s3c2440_buttons_class; static struct class_device *s3c2440_buttons_dev; static DECLARE_WAIT_QUEUE_HEAD(button_waitq); static struct fasync_struct *s3c2440_buttons_async_queue; static struct timer_list s3c2440_button_timer; struct timer_data { int irq; void *dev_id; }; static struct timer_data s3c2440_timer_data; /* 中断事件标志，中断服务程序将它设置为1，read函数内将它清0 */ static unsigned long ev_press = 0; static unsigned char key_val; struct pin_desc { unsigned int pin; unsigned char key_val; }; static struct pin_desc pins_desc[4] = { {S3C2410_GPF0, 0x01}, {S3C2410_GPF2, 0x02}, {S3C2410_GPG3, 0x03}, {S3C2410_GPG11, 0x04}, }; /* * 确定按键值 */ static irqreturn_t s3c2440_buttons_handler(int irq, void *dev_id) { /* 10ms后启动定时器 */ mod_timer(&s3c2440_button_timer, jiffies + (HZ/100)); s3c2440_timer_data.irq = irq; s3c2440_timer_data.dev_id = dev_id; return IRQ_HANDLED; } static void s3c2440_buttons_timer(unsigned long data) { struct pin_desc *pindesc = (struct pin_desc *)s3c2440_timer_data.dev_id; if (pindesc == NULL) return; unsigned char pinval; pinval = s3c2410_gpio_getpin(pindesc->pin); /* 读出引脚值 */ if (pinval) { /* 按键松开 */ key_val = 0x80 | pindesc->key_val; } else { /* 按键按下 */ key_val = pindesc->key_val; } ev_press = 1; wake_up_interruptible(&button_waitq); kill_fasync(&s3c2440_buttons_async_queue, SIGIO, POLL_IN); } static unsigned s3c2440_buttons_poll(struct file *file, poll_table *wait) { unsigned int mask = 0; poll_wait(file, &button_waitq, wait); if (ev_press) mask |= POLLIN | POLLRDBAND; return mask; } static ssize_t s3c2440_buttons_close(struct inode *inode, struct file *file) { free_irq(IRQ_EINT0, &pins_desc[0]); free_irq(IRQ_EINT2, &pins_desc[1]); free_irq(IRQ_EINT11, &pins_desc[2]); free_irq(IRQ_EINT19, &pins_desc[3]); return 0; } static ssize_t s3c2440_buttons_open(struct inode *inode, struct file *file) { /* 配置按键：GPF0\2和GPG3的引脚为中断引脚 * 注册irqaction处理函数 */ request_irq(IRQ_EINT0, s3c2440_buttons_handler, IRQT_BOTHEDGE, "s2", &pins_desc[0]); request_irq(IRQ_EINT2, s3c2440_buttons_handler, IRQT_BOTHEDGE, "s3", &pins_desc[1]); request_irq(IRQ_EINT11, s3c2440_buttons_handler, IRQT_BOTHEDGE, "s4", &pins_desc[2]); request_irq(IRQ_EINT19, s3c2440_buttons_handler, IRQT_BOTHEDGE, "s5", &pins_desc[3]); return 0; } static ssize_t s3c2440_buttons_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { return 0; } static ssize_t s3c2440_buttons_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { unsigned long ret; if (count < sizeof(key_val)) return -EINVAL; /* 如果没有按键按下，就休眠 */ wait_event_interruptible(button_waitq, ev_press); /* 如果有按键被按下，从休眠状态唤醒 */ ret = copy_to_user(buf, &key_val, sizeof(key_val)); ev_press = 0; return ret; } int s3c2440_buttons_fasync(int fd, struct file * file, int on) { return fasync_helper(fd, file, on, &s3c2440_buttons_async_queue); } static struct file_operations s3c2440_buttons_fops = { .owner = THIS_MODULE, .open = s3c2440_buttons_open, .read = s3c2440_buttons_read, .write = s3c2440_buttons_write, .release = s3c2440_buttons_close, .poll = s3c2440_buttons_poll, .fasync = s3c2440_buttons_fasync, }; static int __init s3c2440_buttons_init(void) { major = register_chrdev(0, DEVICE_NAME, &s3c2440_buttons_fops); if (major < 0) { printk(DEVICE_NAME " can't register major number\n"); return major; } s3c2440_buttons_class = class_create(THIS_MODULE, "s3c2440_buttons_poll"); if (IS_ERR(s3c2440_buttons_class)) return PTR_ERR(s3c2440_buttons_class); /* 在/sys/s3c2440_leds目录下创建一个设备，设备的目录为leds * 同时触发mdev在/dev目录下生成一个名为leds的设备节点 */ s3c2440_buttons_dev = class_device_create(s3c2440_buttons_class, NULL, MKDEV(major, 0), NULL, "button_shake"); if (unlikely(IS_ERR(s3c2440_buttons_dev))) return PTR_ERR(s3c2440_buttons_dev); init_timer(&s3c2440_button_timer); s3c2440_button_timer.data = NULL; s3c2440_button_timer.function = s3c2440_buttons_timer; add_timer(&s3c2440_button_timer); printk(DEVICE_NAME " initialized!\n"); return 0; } static void __exit s3c2440_buttons_exit(void) { /* 卸载驱动程序 */ class_device_destroy(s3c2440_buttons_class, MKDEV(major, 0)); class_destroy(s3c2440_buttons_class); unregister_chrdev(major, DEVICE_NAME); del_timer(&s3c2440_button_timer); printk(DEVICE_NAME " unregister\n"); } module_init(s3c2440_buttons_init); module_exit(s3c2440_buttons_exit); MODULE_LICENSE("GPL");