#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include <linux/spinlock.h>
#include <linux/irq.h>
#include <linux/delay.h>
#include <asm/hardware.h>
#define DEVICE_NAME "buttons" /*定義按鍵設備名*/
#define BUTTON_MAJOR 232 /*定義按鍵主設備號*/
static struct key_info {
int irq_no;
unsigned int gpio_port;
int key_no;
} key_info_tab[4] = { /*按鍵所使用的CPU資源*/
{ IRQ_EINT1, GPIO_F1, 1 },
{ IRQ_EINT2, GPIO_F2, 2 },
{ IRQ_EINT3, GPIO_F3, 3 },
{ IRQ_EINT7, GPIO_F7, 4 },
};
static int ready = 0;
static int key_value = 0;
static DECLARE_WAIT_QUEUE_HEAD(buttons_wait);
/*按鍵的中斷服務程序*/
static void buttons_irq(int irq, void *dev_id, struct pt_regs *reg)
{
struct key_info *k;
int i;
int found = 0;
int up;
int flags;
for (i = 0; i < sizeof key_info_tab / sizeof key_info_tab[1]; i++) {
k = key_info_tab + i;
if (k->irq_no == irq) {
found = 1;
break;
}
}
if (!found) {
printk("bad irq %d in button\n", irq);
return;
}
save_flags(flags);
cli();
set_gpio_mode_user(k->gpio_port, GPIO_MODE_IN);
up = read_gpio_bit(k->gpio_port);
set_external_irq(k->irq_no, EXT_BOTH_EDGES, GPIO_PULLUP_DIS);
restore_flags(flags);
if (up) {
key_value = k->key_no + 0x80;
} else {
key_value = k->key_no;
}
ready = 1;
wake_up_interruptible(&buttons_wait);
}
/*申請系統中斷，中斷方式為雙邊觸發，即在上升沿和下降沿均發生中斷*/
static int request_irqs(void)
{
struct key_info *k;
int i;
for (i = 0; i < sizeof key_info_tab / sizeof key_info_tab[1]; i++) {
k = key_info_tab + i;
set_external_irq(k->irq_no, EXT_BOTH_EDGES, GPIO_PULLUP_DIS);
if (request_irq(k->irq_no, &buttons_irq, SA_INTERRUPT, DEVICE_NAME, &buttons_irq)) {
return -1;
}
}
return 0;
}
/*釋放中斷*/
static void free_irqs(void)
{struct key_info *k;
int i;
for (i = 0; i < sizeof key_info_tab / sizeof key_info_tab[1]; i++) {
k = key_info_tab + i;
free_irq(k->irq_no, buttons_irq);
}
}
/*file_operations的“讀“指針函數實現*/
static int matrix4_buttons_read(struct file * file, char * buffer, size_t count, loff_t *ppos)
{
static int key;
int flags;
int repeat;
if (!ready)
return -EAGAIN;
if (count != sizeof key_value)
return -EINVAL;
save_flags(flags);
if (key != key_value) {
key = key_value;
repeat = 0;
} else {
repeat = 1;
}
restore_flags(flags);
if (repeat) {
return -EAGAIN;
}
/*使用copy_to_user把鍵值送到用戶空間*/
copy_to_user(buffer, &key, sizeof key);
ready = 0;
return sizeof key_value;
}
static unsigned int matrix4_buttons_select(
struct file *file,
struct poll_table_struct *wait)
{
if (ready)
return 1;
poll_wait(file, &buttons_wait, wait);
return 0;
}
static int matrix4_buttons_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
switch(cmd) {
default:
return -EINVAL;
}
}
static struct file_operations matrix4_buttons_fops = {
owner: THIS_MODULE,
ioctl: matrix4_buttons_ioctl,
poll: matrix4_buttons_select,
read: matrix4_buttons_read,
};
static devfs_handle_t devfs_handle;
/*按鍵初始化*/
static int __init matrix4_buttons_init(void)
{
int ret;
ready = 0;
/*注冊按鍵設備*/
ret = register_chrdev(BUTTON_MAJOR, DEVICE_NAME, &matrix4_buttons_fops);
if (ret < 0) {
printk(DEVICE_NAME " can't register major number\n");
return ret;
}
ret = request_irqs();
if (ret) {
unregister_chrdev(BUTTON_MAJOR, DEVICE_NAME);
printk(DEVICE_NAME " can't request irqs\n");
return ret;
}
devfs_handle = devfs_register(NULL, DEVICE_NAME, DEVFS_FL_DEFAULT,
BUTTON_MAJOR, 0, S_IFCHR | S_IRUSR | S_IWUSR, &matrix4_buttons_fops, NULL);
return 0;
}
static void __exit matrix4_buttons_exit(void)
{
devfs_unregister(devfs_handle);
free_irqs();
unregister_chrdev(BUTTON_MAJOR, DEVICE_NAME);
}
module_init(matrix4_buttons_init);
module_exit(matrix4_buttons_exit);
MODULE_LICENSE("GPL");