mini2440 buttons的驱动-linux3.10.59-优快云博客

本文介绍了一个针对mini2440开发板的按钮驱动程序实现，该驱动基于Linux 3.10.59内核，通过IRQ中断处理实现了按钮的状态读取功能。

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mini2440 buttons的驱动-linux3.10.59

/* linux/drivers/char/mini2440_buttons.c
 *	Copyright (c) 2013 Feng Guoqing
 *
 * mini2440 buttons Driver
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive for
 * more details.
 *
*/

#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; 

    down = !gpio_get_value(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("FriendlyARM Inc.");