EPC-6708 按键驱动

/*
 * linux/drivers/char/tiny4412_buttons.c
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */


#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/sched.h>
#include <linux/irq.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
#include <mach/hardware.h>
#include <linux/platform_device.h>
#include <linux/cdev.h>
#include <linux/miscdevice.h>
#include <linux/gpio.h>


#include <mach/gpio.h>
#define DEVICE_NAME "mybutton"


struct button_desc {
int gpio;
int number;
char *name;
struct timer_list timer;
};


static struct button_desc buttons[] = {
{ IMX_GPIO_NR(1,0), 0, "KEY0" },
{ IMX_GPIO_NR(1,2), 1, "KEY1" },
{ IMX_GPIO_NR(1,4), 2, "KEY2" },
{ IMX_GPIO_NR(1,5), 3, "KEY3" },
};


static volatile char key_values[] = {
'0', '0', '0', '0', '0', '0', '0', '0'
};


static DECLARE_WAIT_QUEUE_HEAD(button_waitq);


static volatile int ev_press = 0;


static void tiny4412_buttons_timer(unsigned long _data)
{
struct button_desc *bdata = (struct button_desc *)_data;
int down;
int number;
unsigned tmp;


tmp = gpio_get_value(bdata->gpio);


/* active low */
down = !tmp;
printk(KERN_DEBUG "KEY %d: %08x\n", bdata->number, down);


number = bdata->number;
if (down != (key_values[number] & 1)) {
key_values[number] = '0' + down;


ev_press = 1;
wake_up_interruptible(&button_waitq);
}
}


static irqreturn_t button_interrupt(int irq, void *dev_id)
{
struct button_desc *bdata = (struct button_desc *)dev_id;


mod_timer(&bdata->timer, jiffies + msecs_to_jiffies(40));


return IRQ_HANDLED;
}


static int tiny4412_buttons_open(struct inode *inode, struct file *file)
{
int irq;
int i;
int err = 0;


for (i = 0; i < ARRAY_SIZE(buttons); i++) {
if (!buttons[i].gpio)
continue;
//初始化定时器。
setup_timer(&buttons[i].timer, tiny4412_buttons_timer,
(unsigned long)&buttons[i]);


irq = gpio_to_irq(buttons[i].gpio);
//上升沿和下降沿触发
err = request_irq(irq, button_interrupt, IRQ_TYPE_EDGE_BOTH, 
buttons[i].name, (void *)&buttons[i]);
if (err)
break;
}


if (err) {
i--;
for (; i >= 0; i--) {
if (!buttons[i].gpio)
continue;


irq = gpio_to_irq(buttons[i].gpio);
disable_irq(irq);
free_irq(irq, (void *)&buttons[i]);


del_timer_sync(&buttons[i].timer);
}


return -EBUSY;
}


ev_press = 1;
return 0;
}


static int tiny4412_buttons_close(struct inode *inode, struct file *file)
{
int irq, i;


for (i = 0; i < ARRAY_SIZE(buttons); i++) {
if (!buttons[i].gpio)
continue;


irq = gpio_to_irq(buttons[i].gpio);
free_irq(irq, (void *)&buttons[i]);


del_timer_sync(&buttons[i].timer);
}


return 0;
}


static int tiny4412_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((void *)buff, (const void *)(&key_values),
min(sizeof(key_values), count));


return err ? -EFAULT : min(sizeof(key_values), count);
}


static unsigned int tiny4412_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 = tiny4412_buttons_open,
.release = tiny4412_buttons_close, 
.read = tiny4412_buttons_read,
.poll = tiny4412_buttons_poll,
};


static struct miscdevice misc = {
.minor = MISC_DYNAMIC_MINOR,
.name = DEVICE_NAME,
.fops = &dev_fops,
};


static int __init button_dev_init(void)
{
int ret;


ret = misc_register(&misc);


printk(DEVICE_NAME"\tinitialized\n");


return ret;
}


static void __exit button_dev_exit(void)
{
misc_deregister(&misc);
}


module_init(button_dev_init);
module_exit(button_dev_exit);


MODULE_LICENSE("GPL");

MODULE_AUTHOR("FriendlyARM Inc.");

Makefile

ifneq ($(KERNELRELEASE),)
obj-m:=my4412_buttons.o
else
#KDIR := /lib/modules/$(shell uname -r)/build
KDIR = /home/xxq/kernel-imx/
PWD := $(shell pwd)
all:
make -C  $(KDIR) M=$(PWD)  modules
clean:
rm *.mod.c *.o *.ko *.order *.symvers
endif

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/select.h>
#include <sys/time.h>
#include <errno.h>
int main(void)
{
int buttons_fd;
char buttons[6] = {'0', '0', '0', '0', '0', '0'};
buttons_fd = open("/dev/mybutton", 0);
if (buttons_fd < 0) {
perror("open device buttons");
exit(1);
}
for (;;) {
char current_buttons[6];
int count_of_changed_key;
int i;
if (read(buttons_fd, current_buttons, sizeof current_buttons) != sizeof
current_buttons) {
perror("read buttons:");
exit(1);
}
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];
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");
}
}
close(buttons_fd);
return 0;
}

测试说明：

1.文件目录make ARCH=arm CROSS_COMPILE=arm-linux- ，生成my4412_buttons.ko

2.arm-none-linux-gnueabi-gcc test.c -o test 生成test

2.加载驱动模块：insmod my4412_buttons.ko

3.运行test测试。