module_init(dev_init);//模块初始化,仅当使用 insmod/podprobe 命令加载时有用,如果设备不是通过模块方式加载,此处将不会被调用
module_exit(dev_exit);//卸载模块,当该设备通过模块方式加载后,可以通过 rmmod 命令卸载,将调用此函数
MODULE_LICENSE("GPL");//版权信息
MODULE_AUTHOR("tang");//作者名字
测试程序btn_test.c
#include #include #include #include #include #include #include #include #include #include
int main(void)
{
int buttons_fd;
char buttons[6] = {'0', '0', '0', '0', '0', '0'}; //定义按键值变量,对于驱动函数中的 key_values 数组
/*打开按键设备/dev/buttons*/
buttons_fd = open("/dev/buttons", 0);
if (buttons_fd < 0) {
/*打开失败则退出*/
perror("open device buttons");
exit(1);
}
/*永读按键并打印键值和状态*/
for (;;) {
char current_buttons[6];
int count_of_changed_key;
int i;
/*使用 read 函数读取一组按键值(6 个)*/
if (read(buttons_fd, current_buttons, sizeof current_buttons) != sizeof current_buttons) {
perror("read buttons:");
exit(1);
}
/*逐个分析读取到的按键值*/
for (i = 0, count_of_changed_key = 0; i < sizeof buttons / sizeof buttons[0]; i++) {
if (buttons[i] != current_buttons[i]) {
buttons[i] = current_buttons[i];
/*打印按键值,并标明按键按下/抬起的状态*/
printf("%skey %d is %s", count_of_changed_key? ", ": "", i+1, buttons[i] == '0' ? "up" :
"down");
count_of_changed_key++;
}
}
if (count_of_changed_key) {
printf("\n");
}
}
/*关闭按键设备文件*/
close(buttons_fd);
return 0;
}
arm-linux-gcc -o buttons_test buttons_test.c
以下是成功加载范例jd2440_buttons.c，位于linux-2.x.xx/drivers/char下
cp -f jd2440_buttons.c /linux-2.x.xx/drivers/char //把驱动源码复制到内核驱动的字符设备下
#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include
#define DEVICE_NAME "buttons"
struct button_irq_desc {
int irq;
int pin;
int pin_setting;
int number;
char *name;
};
static struct button_irq_desc button_irqs [] = {
{IRQ_EINT11,S3C2410_GPG3, S3C2410_GPG3_EINT11, 0, "KEY0"},//key_right
{IRQ_EINT8, S3C2410_GPG0, S3C2410_GPG0_EINT8, 1, "KEY1"},//key_down
{IRQ_EINT3, S3C2410_GPF3, S3C2410_GPF3_EINT3, 2, "KEY2"},//key_enter
{IRQ_EINT9, S3C2410_GPG1, S3C2410_GPG1_EINT9, 3, "KEY3"},//key_left
{IRQ_EINT1, S3C2410_GPF1, S3C2410_GPF1_EINT1, 4, "KEY4"},//key_up
{IRQ_EINT5, S3C2410_GPF5, S3C2410_GPF5_EINT5, 5, "KEY5"},//usb wakeup
{ -1, -1, -1, 6, "KEY6"},
};
static volatile char key_values [] = {'0', '0', '0', '0', '0', '0'};
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
static volatile int ev_press = 0;
static irqreturn_t buttons_interrupt(int irq, void *dev_id)
{
struct button_irq_desc *button_irqs = (struct button_irq_desc *)dev_id;
int down;
down = !s3c2410_gpio_getpin(button_irqs->pin);
if (down != (key_values[button_irqs->number] & 1)) {
key_values[button_irqs->number] = '0' + down;
ev_press = 1;
wake_up_interruptible(&button_waitq);
}
return IRQ_RETVAL(IRQ_HANDLED);
}
static int s3c24xx_buttons_open(struct inode *inode, struct file *file)
{
int i;
int err = 0;
for (i = 0; i < sizeof(button_irqs)/sizeof(button_irqs[0]); i++) {
if (button_irqs[i].irq < 0) {
continue;
}
err = request_irq(button_irqs[i].irq, buttons_interrupt, IRQ_TYPE_EDGE_BOTH,
button_irqs[i].name, (void *)&button_irqs[i]);
if (err)
break;
}
if (err) {
i--;
for (; i >= 0; i--) {
if (button_irqs[i].irq < 0) {
continue;
}
disable_irq(button_irqs[i].irq);
free_irq(button_irqs[i].irq, (void *)&button_irqs[i]);
}
return -EBUSY;
}
ev_press = 1;
return 0;
}
static int s3c24xx_buttons_close(struct inode *inode, struct file *file)
{
int i;
for (i = 0; i < sizeof(button_irqs)/sizeof(button_irqs[0]); i++) {
if (button_irqs[i].irq < 0) {
continue;
}
free_irq(button_irqs[i].irq, (void *)&button_irqs[i]);
}
return 0;
}
static int s3c24xx_buttons_read(struct file *filp, char __user *buff, size_t count, loff_t *offp)
{
unsigned long err;
if (!ev_press) {
if (filp->f_flags & O_NONBLOCK)
return -EAGAIN;
else
wait_event_interruptible(button_waitq, ev_press);
}
ev_press = 0;
err = copy_to_user(buff, (const void *)key_values, min(sizeof(key_values), count));
return err ? -EFAULT : min(sizeof(key_values), count);
}
static unsigned int s3c24xx_buttons_poll( struct file *file, struct poll_table_struct *wait)
{
unsigned int mask = 0;
poll_wait(file, &button_waitq, wait);
if (ev_press)
mask |= POLLIN | POLLRDNORM;
return mask;
}
static struct file_operations dev_fops = {
.owner = THIS_MODULE,
.open = s3c24xx_buttons_open,
.release = s3c24xx_buttons_close,
.read = s3c24xx_buttons_read,
.poll = s3c24xx_buttons_poll,
};
static struct miscdevice misc = {
.minor = MISC_DYNAMIC_MINOR,
.name = DEVICE_NAME,
.fops = &dev_fops,
};
static int __init dev_init(void)
{
int ret;
ret = misc_register(&misc);
printk (DEVICE_NAME"\tinitialized\n");
return ret;
}
static void __exit dev_exit(void)
{
misc_deregister(&misc);
}
module_init(dev_init);
module_exit(dev_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("modelsim");
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