#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/interrupt.h>
#include < asm/uaccess.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/sched.h>
#include < linux/gpio.h>
#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_EINT8 , S3C2410_GPG(0) , S3C2410_GPG0_EINT8 , 0, "KEY0"},
{IRQ_EINT11, S3C2410_GPG(3) , S3C2410_GPG3_EINT11 , 1, "KEY1"},
{IRQ_EINT13, S3C2410_GPG(5) , S3C2410_GPG5_EINT13 , 2, "KEY2"},
{IRQ_EINT14, S3C2410_GPG(6) , S3C2410_GPG6_EINT14 , 3, "KEY3"},
{IRQ_EINT15, S3C2410_GPG(7) , S3C2410_GPG7_EINT15 , 4, "KEY4"},
{IRQ_EINT19, S3C2410_GPG(11), S3C2410_GPG11_EINT19, 5, "KEY5"},
};
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;
// udelay(0);
down = !s3c2410_gpio_getpin(button_irqs->pin);
if (down != (key_values[button_irqs->number] & 1)) { // Changed
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("FriendlyARM Inc.");下面用程式碼片段，拆開來一步一步學習。
首先，先說linux device driver的架構，大致上的linux device driver，都會長的像下面這樣，
#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/interrupt.h>
#include < asm/uaccess.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/sched.h>
#include < linux/gpio.h>
static int s3c24xx_buttons_open(struct inode *inode, struct file *file)
{
...
}
static int s3c24xx_buttons_close(struct inode *inode, struct file *file)
{
...
}
static int s3c24xx_buttons_read(struct file *filp, char __user *buff, size_t count, loff_t *offp)
{
...
}
static struct file_operations dev_fops = {
.owner = THIS_MODULE,
.open = s3c24xx_buttons_open,
.release = s3c24xx_buttons_close,
.read = s3c24xx_buttons_read,
};
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("FriendlyARM Inc.");
