本文主要是介绍micro2440利用LEDS与BUTTONS驱动实现按键控制led灯【开发总结】，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
最近玩友善之臂的micro2440，实现了按键控制led灯亮灭的功能。在这里总结一下，有什么错误希望高手们能指点一下，同时也希望能够帮到刚学驱动的新手。
首先贴出leds驱动程序：
#include <linux/miscdevice.h>
#include <linux/delay.h>
#include <asm/irq.h>
#include <mach/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/ioctl.h>
#include <linux/cdev.h>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/pci.h>
#include <asm/uaccess.h>
#include <asm/atomic.h>
#include <asm/unistd.h>#define DEVICE_NAME "leds"static unsigned long led_table [] = {S3C2410_GPB5,S3C2410_GPB6,S3C2410_GPB7,S3C2410_GPB8,
};static unsigned int led_cfg_table [] = {S3C2410_GPB5_OUTP,S3C2410_GPB6_OUTP,S3C2410_GPB7_OUTP,S3C2410_GPB8_OUTP,
};static int sbc2440_leds_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{switch(cmd) {case 0:case 1:if (arg > 4) {return -EINVAL;}s3c2410_gpio_setpin(led_table[arg], !cmd);return 0;default:return -EINVAL;}
}static struct file_operations dev_fops = {.owner = THIS_MODULE,.ioctl = sbc2440_leds_ioctl,
};static struct miscdevice misc = {.minor = MISC_DYNAMIC_MINOR,.name = DEVICE_NAME,.fops = &dev_fops,
};static int __init dev_init(void)
{int ret;int i;for (i = 0; i < 4; i++) {s3c2410_gpio_cfgpin(led_table[i], led_cfg_table[i]);s3c2410_gpio_setpin(led_table[i], 0);}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.");
此驱动关键的地方是给出了一个ioctl的设备方法，在应用程序中使用ioctl（leds的fd，cmd，arg）系统调用时，系统会进入内核态并调用sbc2440_leds_ioctl(),以控制灯的亮灭。
下面贴出buttons的驱动程序：
#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>#define DEVICE_NAME "buttons"struct button_irq_desc {int irq;int pin;int pin_setting;int number;char *name;
};#if !defined (CONFIG_QQ2440_BUTTONS)
static struct button_irq_desc button_irqs [] = {{IRQ_EINT8 , S3C2410_GPG0 , S3C2410_GPG0_EINT8 , 0, "KEY0"},{IRQ_EINT11, S3C2410_GPG3 , S3C2410_GPG3_EINT11 , 1, "KEY1"},{IRQ_EINT13, S3C2410_GPG5 , S3C2410_GPG5_EINT13 , 2, "KEY2"},{IRQ_EINT14, S3C2410_GPG6 , S3C2410_GPG6_EINT14 , 3, "KEY3"},{IRQ_EINT15, S3C2410_GPG7 , S3C2410_GPG7_EINT15 , 4, "KEY4"},{IRQ_EINT19, S3C2410_GPG11, S3C2410_GPG11_EINT19, 5, "KEY5"},
};
#else /* means QQ */
static struct button_irq_desc button_irqs [] = {{IRQ_EINT19, S3C2410_GPG11, S3C2410_GPG11_EINT19, 0, "KEY0"},{IRQ_EINT11, S3C2410_GPG3, S3C2410_GPG3_EINT11, 1, "KEY1"},{IRQ_EINT2, S3C2410_GPF2, S3C2410_GPF2_EINT2, 2, "KEY2"},{IRQ_EINT0, S3C2410_GPF0, S3C2410_GPF0_EINT0, 3, "KEY3"},{ -1, -1, -1, 4, "KEY4"},{ -1, -1, -1, 5, "KEY5"},
};
#endif
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)) { // Changedkey_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;elsewait_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.");
该驱动的关键(按键驱动的具体分析请看我的另一篇博客 mini2440_buttons.c驱动程序解读)
1.是s3c24xx_buttons_read的设备方法，在应用程序中使用read（buttons的fs，按键状态数组，读多少位）系统调用时，会进入内核态调用该s3c24xx_buttons_read函数,改函数通过wait _event_interruptible()进入可中断的休眠状态，等待中断的到来。
2.是定义了buttons_interrupt中断服务函数，该函数对相应的键值进行处理，并唤醒休眠。
应用程序如下：
#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>
#include<string.h>
int main(void)
{int buttons_fd;char buttons[6] = {'0', '0', '0', '0', '0', '0'};int leds_fd;int save=0;int j = 0;unsigned char s=0;buttons_fd = open("/dev/buttons", 0);if (buttons_fd < 0) {perror("open device buttons");exit(1);}leds_fd = open("/dev/leds",0);if(leds_fd < 0){perror("open device leds");exit(1);}ioctl(leds_fd,0,0);ioctl(leds_fd,0,1);ioctl(leds_fd,0,2);ioctl(leds_fd,0,3);while (1) {// char current_buttons[6]={'0','0','0','0','0','0'};char save[6]={'0','0','0','0','0','0'};int i;//while((strncmp(save,current_buttons,6))==0)//{if (read(buttons_fd, current_buttons, sizeof current_buttons) != sizeof current_buttons) {perror("read buttons:");exit(1);} //}if((strncmp(save,current_buttons,6))==0)continue;for ( i = 0; i < sizeof (current_buttons) / sizeof (current_buttons[0]); i++) {if (save[i] != current_buttons[i]) {// buttons[i] = current_buttons[i];printf("The %d key is pressed!(s=%d)\n",i+1,s);ioctl(leds_fd,(~s)&1,i);}}// end of for s=~s;}//end of while(1)close(buttons_fd);close(leds_fd);return 0;
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