老習慣先貼一波代碼再仔細分析消化。

#include <linux/module.h> #include <linux/kernel.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/delay.h> #include <linux/irq.h> #include <asm/uaccess.h> #include <asm/irq.h> #include <asm/io.h> #include <asm/arch/regs-gpio.h> #include <asm/hardware.h>static struct class *thirddrv_class; static struct class_device *thirddrv_class_dev;volatile unsigned long *gpfcon; volatile unsigned long *gpfdat;volatile unsigned long *gpgcon; volatile unsigned long *gpgdat;static DECLARE_WAIT_QUEUE_HEAD(button_waitq);/* 中斷事件標志, 中斷服務程序將它置1，third_drv_read將它清0 */ static volatile int ev_press = 0;struct pin_desc{unsigned int pin;unsigned int key_val; };/* 鍵值: 按下時, 0x01, 0x02, 0x03, 0x04 */ /* 鍵值: 松開時, 0x81, 0x82, 0x83, 0x84 */ static unsigned char key_val;struct pin_desc pins_desc[4] = {{S3C2410_GPF0, 0x01},{S3C2410_GPF2, 0x02},{S3C2410_GPG3, 0x03},{S3C2410_GPG11, 0x04}, };/** 確定按鍵值*/ static irqreturn_t buttons_irq(int irq, void *dev_id) {struct pin_desc * pindesc = (struct pin_desc *)dev_id;unsigned int pinval;pinval = s3c2410_gpio_getpin(pindesc->pin);if (pinval){/* 松開 */key_val = 0x80 | pindesc->key_val;}else{/* 按下 */key_val = pindesc->key_val;}ev_press = 1; /* 表示中斷發生了 */wake_up_interruptible(&button_waitq); /* 喚醒休眠的進程 */return IRQ_RETVAL(IRQ_HANDLED); }static int third_drv_open(struct inode *inode, struct file *file) {/* 配置GPF0,2為輸入引腳 *//* 配置GPG3,11為輸入引腳 */request_irq(IRQ_EINT0, buttons_irq, IRQT_BOTHEDGE, "S2", &pins_desc[0]);request_irq(IRQ_EINT2, buttons_irq, IRQT_BOTHEDGE, "S3", &pins_desc[1]);request_irq(IRQ_EINT11, buttons_irq, IRQT_BOTHEDGE, "S4", &pins_desc[2]);request_irq(IRQ_EINT19, buttons_irq, IRQT_BOTHEDGE, "S5", &pins_desc[3]); return 0; }ssize_t third_drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) {if (size != 1)return -EINVAL;/* 如果沒有按鍵動作, 休眠 */wait_event_interruptible(button_waitq, ev_press);/* 如果有按鍵動作, 返回鍵值 */copy_to_user(buf, &key_val, 1);ev_press = 0;return 1; }int third_drv_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 struct file_operations sencod_drv_fops = {.owner = THIS_MODULE, /* 這是一個宏，推向編譯模塊時自動創建的__this_module變量 */.open = third_drv_open, .read = third_drv_read, .release = third_drv_close, };int major; static int third_drv_init(void) {major = register_chrdev(0, "third_drv", &sencod_drv_fops);thirddrv_class = class_create(THIS_MODULE, "third_drv");thirddrv_class_dev = class_device_create(thirddrv_class, NULL, MKDEV(major, 0), NULL, "buttons"); /* /dev/buttons */gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);gpfdat = gpfcon + 1;gpgcon = (volatile unsigned long *)ioremap(0x56000060, 16);gpgdat = gpgcon + 1;return 0; }static void third_drv_exit(void) {unregister_chrdev(major, "third_drv");class_device_unregister(thirddrv_class_dev);class_destroy(thirddrv_class);iounmap(gpfcon);iounmap(gpgcon);return 0; }module_init(third_drv_init);module_exit(third_drv_exit);MODULE_LICENSE("GPL");

應用層代碼如下

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#include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <unistd.h>/* thirddrvtest */ int main(int argc, char **argv) {int fd;unsigned char key_val;fd = open("/dev/buttons", O_RDWR);if (fd < 0){printf("can't open!\n");}while (1){//read(fd, &key_val, 1);//printf("key_val = 0x%x\n", key_val);sleep(5);}return 0; }

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