FL2440驱动添加（4）LED 驱动添加

硬件信息：FL2440板子，s3c2440CPU带四个LED，分别在链接GPB5，GPB6，GPB8，GPB10

内核版本：linux-3.8.0

led驱动代码如下：

值得注意地方地方：

1，定时器的使用：在include/linux/timer.h下定义struct timer_list

struct timer_list {
/*
* All fields that change during normal runtime grouped to the
* same cacheline
*/
struct list_head entry;
unsigned long expires;
struct tvec_base *base;

void (*function)(unsigned long);
unsigned long data;

int slack;

#ifdef CONFIG_TIMER_STATS
int start_pid;
void *start_site;
char start_comm[16];
#endif
#ifdef CONFIG_LOCKDEP
struct lockdep_map lockdep_map;
#endif
};

 详细参考：linux-2.4.18内核定时器的使用

2，设置GPIO函数有中，linux-3.8.0和linux-3.0.0有所不同，具体可以参考Documentation/arm/Samsung-S3C24XX/GPIO.txt中的说明,只列出遇到变换：

	linux-3.8.0	linux-3.0.0	参数是否变化
设置GPIO高或低	gpio_set_value（）	s3c2410_gpio_setpin()	不变
设置GPIO工作方式	s3c_gpio_cfgpin()	s3c2410_gpio_cfgpin()	不变

 

3，Linux核心几个重要跟时间有关的名词或变数，HZ、tick和jiffies之间关系。

HZ：Linux核心每隔固定周期会发出timer interrupt ，HZ是用来定义每一秒有几次timer interrupts，我的机器为100 timer interrupts。 

tick:就是HZ的倒数，以秒表示

jiffies：Jiffies为Linux核心变数(32位元变数，unsigned long)，它被用来纪录系统自开机以来的tick数，每发生一次timer interrupt，Jiffies变数会被加一。

4，设备节点自动创建函数：class_create()和device_create（）

从linux 内核2.6.24的某个版本之后，devfs不复存在，udev成为devfs的替代。udev处于应用层;加入对udev的支持很简单，以一个字符设备驱动led为例，在驱动初始化的代码里调用class_create为该设备创建一个class，再为每个设备调用 device_create创建对应的设备。

大致用法如下：
struct class *class = class_create(THIS_MODULE, “led”);
device_create(class, NULL, MKDEV(major_num, 0), NULL, “led”);
这样的module被加载时，udev daemon就会自动在/dev下创建led设备文件。

led驱动代码plat_led.c：

/*********************************************************************************
* Copyright: (C) 2011 Guo Wenxue<guowenxue@gmail.com> 
* All rights reserved.
*
* Filename: s3c_led.c
* Description: This is the common LED driver runs on S3C24XX.
* 
* Version: 1.0.0(10/27/2011~)
* Author: Guo Wenxue <guowenxue@gmail.com>
* ChangeLog: 1, Release initial version on "10/27/2011 11:39:10 AM"
* 
********************************************************************************/
#include "s3c_driver.h"

#define DRV_AUTHOR "Guo Wenxue <guowenxue@gmail.com>"
#define DRV_DESC "S3C24XX LED driver"

/* Driver version*/
#define DRV_MAJOR_VER 1
#define DRV_MINOR_VER 0
#define DRV_REVER_VER 0

#define DEV_NAME DEV_LED_NAME

//#define DEV_MAJOR DEV_LED_MAJOR
#ifndef DEV_MAJOR
#define DEV_MAJOR 0 /* dynamic major by default */


#define TIMER_TIMEOUT 40

static int debug = DISABLE;
static int dev_major = DEV_MAJOR;
static int dev_minor = 0;



/* ============================ Platform Device part ===============================*/
/* LED hardware informtation structure*/
struct s3c_led_info
{
unsigned char num; /* The LED number */
unsigned int gpio; /* Which GPIO the LED used */
unsigned char active_level; /* The GPIO pin level(HIGHLEVEL or LOWLEVEL) to turn on or off */
unsigned char status; /* Current LED status: OFF/ON */
unsigned char blink; /* Blink or not */
};

/* The LED platform device private data structure */
struct s3c_led_platform_data
{
struct s3c_led_info *leds;
int nleds;
};



/* LED hardware informtation data*/
static struct s3c_led_info s3c_leds[] = {
[0] = {
.num = 1,
.gpio = S3C2410_GPB(5),
.active_level = LOWLEVEL,
.status = ON,
.blink = DISABLE,
},
[1] = {
.num = 2,
.gpio = S3C2410_GPB(6),
.active_level = LOWLEVEL,
.status = OFF,
.blink = DISABLE,
},
[2] = {
.num = 3,
.gpio = S3C2410_GPB(8),
.active_level = LOWLEVEL,
.status = OFF,
.blink = DISABLE,
},
[3] = {
.num = 4,
.gpio = S3C2410_GPB(10),

.active_level = LOWLEVEL,
.status = OFF,
.blink = DISABLE,
},
};



/* The LED platform device private data */
static struct s3c_led_platform_data s3c_led_data = {
.leds = s3c_leds,
.nleds = ARRAY_SIZE(s3c_leds),
};

struct led_device
{
struct s3c_led_platform_data *data;
struct cdev cdev;
struct class *dev_class;
struct timer_list blink_timer;
} led_device;



static void platform_led_release(struct device * dev)
{
int i;
struct s3c_led_platform_data *pdata = dev->platform_data;

dbg_print("%s():%d
", __FUNCTION__,__LINE__);

/* Turn all LED off */
for(i=0; i<pdata->nleds; i++)
{
/* for linux-3.8.0 */
gpio_set_value(pdata->leds[i].gpio, ~pdata->leds[i].active_level);

#if 0
/* for linux-3.0.0 check in s3c2410_gpio_setpin() in Documentation/arm/Samsung-S3C24XX/GPIO.txt*/
s3c2410_gpio_setpin(pdata->leds[i].gpio, ~pdata->leds[i].active_level);
#endif
}
}



static struct platform_device s3c_led_device = {
.name = "s3c_led",
.id = 1,
.dev =
{
.platform_data = &s3c_led_data,
.release = platform_led_release,
},
};


/* ===================== led device driver part ===========================*/

void led_timer_handler(unsigned long data)
{
    int  i;
    struct s3c_led_platform_data *pdata = (struct s3c_led_platform_data *)data;

    for(i=0; i<pdata->nleds; i++)
    {
        if(ON == pdata->leds[i].status)
        {
              gpio_set_value(pdata->leds[i].gpio, pdata->leds[i].active_level);
        }
        else
        {
              gpio_set_value(pdata->leds[i].gpio, ~pdata->leds[i].active_level);
        }

        if(ENABLE == pdata->leds[i].blink )  /* LED should blink */
        {
            /* Switch status between 0 and 1 to turn LED ON or off */
            pdata->leds[i].status = pdata->leds[i].status ^ 0x01;
        }

        /* time clock */
        mod_timer(&(led_device.blink_timer), jiffies + TIMER_TIMEOUT);
    }
}


static int led_open(struct inode *inode, struct file *file)
{
    struct led_device *pdev ;
    struct s3c_led_platform_data *pdata;

    pdev = container_of(inode->i_cdev, struct led_device, cdev);
    pdata = pdev->data;

    file->private_data = pdata;

    return 0;
}


static int led_release(struct inode *inode, struct file *file)
{
    return 0;
}


static void print_led_help(void)
{
    printk("Follow is the ioctl() command for LED driver:
");
    printk("Enable Driver debug command: %u
", SET_DRV_DEBUG);
    printk("Get Driver verion  command : %u
", GET_DRV_VER);
    printk("Turn LED on command        : %u
", LED_ON);
    printk("Turn LED off command       : %u
", LED_OFF);
    printk("Turn LED blink command     : %u
", LED_BLINK);
}


/* compatible with kernel version >=2.6.38*/
static long led_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    struct s3c_led_platform_data *pdata = file->private_data;

    switch (cmd)
    {
        case SET_DRV_DEBUG:
            dbg_print("%s driver debug now.
", DISABLE == arg ? "Disable" : "Enable");
            debug = (0==arg) ? DISABLE : ENABLE;
            break;
        case GET_DRV_VER:
            print_version(DRV_VERSION);
            return DRV_VERSION;

        case LED_OFF:
            if(pdata->nleds <= arg)
            {
               printk("LED%ld doesn't exist
", arg);
               return -ENOTTY;
            }
            pdata->leds[arg].status = OFF;
            pdata->leds[arg].blink = DISABLE;
            break;

        case LED_ON:
              if(pdata->nleds <= arg)
            {
               printk("LED%ld doesn't exist
", arg);
               return -ENOTTY;
            }
            pdata->leds[arg].status = ON;
            pdata->leds[arg].blink = DISABLE;
            break;

        case LED_BLINK:
            if(pdata->nleds <= arg)
            {
               printk("LED%ld doesn't exist
", arg);
               return -ENOTTY;
            }
            pdata->leds[arg].blink = ENABLE;
            pdata->leds[arg].status = ON;
            break;

        default:
            dbg_print("%s driver don't support ioctl command=%d
", DEV_NAME, cmd);
            print_led_help();
            return -EINVAL;
 
    }
    return 0;
}


static struct file_operations led_fops = {
    .owner = THIS_MODULE,
    .open = led_open,
    .release = led_release,
    .unlocked_ioctl = led_ioctl, /* compatible with kernel version >=2.6.38*/
};


static int s3c_led_probe(struct platform_device *dev)
{
    struct s3c_led_platform_data *pdata = dev->dev.platform_data;
    int result = 0;
    int i;
    dev_t devno;

    /* Initialize the LED status */
    for(i=0; i<pdata->nleds; i++)
    {
         s3c_gpio_cfgpin(pdata->leds[i].gpio, S3C2410_GPIO_OUTPUT);
         if(ON == pdata->leds[i].status)
         {
            gpio_set_value(pdata->leds[i].gpio, pdata->leds[i].active_level);
         }
         else
         {
            gpio_set_value(pdata->leds[i].gpio, ~pdata->leds[i].active_level);
         }
    }
    /*  Alloc the device for driver */
    if (0 != dev_major)
    {
        devno = MKDEV(dev_major, dev_minor);
        result = register_chrdev_region(devno, 1, DEV_NAME);
    }
    else
    {
        result = alloc_chrdev_region(&devno, dev_minor, 1, DEV_NAME);
        dev_major = MAJOR(devno);
    }

    /* Alloc for device major failure */
    if (result < 0)
    {
        printk("%s driver can't get major %d
", DEV_NAME, dev_major);
        return result;
    }


    /* Initialize button structure and register cdev*/
    memset(&led_device, 0, sizeof(led_device));
    led_device.data = dev->dev.platform_data;
    cdev_init (&(led_device.cdev), &led_fops);
    led_device.cdev.owner  = THIS_MODULE;

    result = cdev_add (&(led_device.cdev), devno , 1);
    if (result)
    {
        printk (KERN_NOTICE "error %d add %s device", result, DEV_NAME);
        goto ERROR;
    }

    led_device.dev_class = class_create(THIS_MODULE, DEV_NAME);
    if(IS_ERR(led_device.dev_class))
    {
        printk("%s driver create class failture
",DEV_NAME);
        result =  -ENOMEM;
        goto ERROR;
    }

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,24)     
    device_create(led_device.dev_class, NULL, devno, NULL, DEV_NAME);
#else
    device_create(led_device.dev_class, NULL, devno, DEV_NAME);
#endif

    /*  Initial the LED blink timer */
    init_timer(&(led_device.blink_timer));
    led_device.blink_timer.function = led_timer_handler;
    led_device.blink_timer.data = (unsigned long)pdata;  //pass to led_timer_handler()
    led_device.blink_timer.expires  = jiffies + TIMER_TIMEOUT;
    add_timer(&(led_device.blink_timer));

    printk("S3C %s driver version %d.%d.%d initiliazed.
", DEV_NAME, DRV_MAJOR_VER, DRV_MINOR_VER, DRV_REVER_VER);

    return 0;


ERROR:
    printk("S3C %s driver version %d.%d.%d install failure.
", DEV_NAME, DRV_MAJOR_VER, DRV_MINOR_VER, DRV_REVER_VER);
    cdev_del(&(led_device.cdev));

    unregister_chrdev_region(devno, 1);
    return result;

}



static int s3c_led_remove(struct platform_device *dev)
{
    dev_t devno = MKDEV(dev_major, dev_minor);

    del_timer(&(led_device.blink_timer));

    cdev_del(&(led_device.cdev));
    device_destroy(led_device.dev_class, devno);
    class_destroy(led_device.dev_class);

    unregister_chrdev_region(devno, 1);
    printk("S3C %s driver removed
", DEV_NAME);

    return 0;
}


static struct platform_driver s3c_led_driver = {
    .probe      = s3c_led_probe,
    .remove     = s3c_led_remove,
    .driver     = {
        .name       = "s3c_led",
        .owner      = THIS_MODULE,
    },
};


static int __init s3c_led_init(void)
{
   int       ret = 0;

   ret = platform_device_register(&s3c_led_device);
   if(ret)
   {
        printk(KERN_ERR "%s:%d: Can't register platform device %d
", __FUNCTION__,__LINE__, ret);
        goto fail_reg_plat_dev;
   }
   dbg_print("Regist S3C LED Platform Device successfully.
");

   ret = platform_driver_register(&s3c_led_driver);
   if(ret)
   {
        printk(KERN_ERR "%s:%d: Can't register platform driver %d
", __FUNCTION__,__LINE__, ret);
        goto fail_reg_plat_drv;
   }
   dbg_print("Regist S3C LED Platform Driver successfully.
");

   return 0;

fail_reg_plat_drv:
   platform_driver_unregister(&s3c_led_driver);
fail_reg_plat_dev:
   return ret;
}


static void s3c_led_exit(void)
{
    dbg_print("%s():%d remove LED platform drvier
", __FUNCTION__,__LINE__);
    platform_driver_unregister(&s3c_led_driver);
    dbg_print("%s():%d remove LED platform device
", __FUNCTION__,__LINE__);
    platform_device_unregister(&s3c_led_device);
}

module_init(s3c_led_init);
module_exit(s3c_led_exit);

module_param(debug, int, S_IRUGO);
module_param(dev_major, int, S_IRUGO);
module_param(dev_minor, int, S_IRUGO);

MODULE_AUTHOR(DRV_AUTHOR);
MODULE_DESCRIPTION(DRV_DESC);
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:S3C24XX_led");




s3c_driver.h头文件:

/********************************************************************************
* Copyright: (C) GuoWenxue <guowenxue@gmail.com>
* All rights reserved.
*
* Filename: s3c_driver.h
* Description: This is the common head file for S3C24XX common driver
*
* Version: 1.0.0(10/29/2011~)
* Author: Guo Wenxue <guowenxue@gmail.com>
* ChangeLog: 1, Release initial version on "10/29/2011 11:27:50 AM"
*
********************************************************************************/

#ifndef __S3C_DRIVER_H
#define __S3C_DRIVER_H

#include <linux/version.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/kref.h>
#include <linux/spinlock.h>
#include <asm/uaccess.h>
#include <linux/mutex.h>
#include <linux/delay.h>

#include <linux/fs.h>
#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/string.h>
#include <linux/bcd.h>
#include <linux/miscdevice.h>
#include <linux/poll.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/sysfs.h>
#include <linux/proc_fs.h>
#include <linux/rtc.h>
#include <linux/spinlock.h>
#include <linux/usb.h>
#include <asm/uaccess.h>
#include <asm/delay.h>
#include <linux/syscalls.h> /* For sys_access*/
#include <linux/platform_device.h>
#include <linux/unistd.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>
#include <linux/serial_core.h>
#include <linux/irq.h>
#include <mach/regs-gpio.h>
#include <linux/gpio.h> //linux-3.8.0的GPIO控制

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,32)
#include <mach/hardware.h>
#include <mach/gpio.h>
#include <asm/irq.h>
#else
#include <asm-arm/irq.h>
#include <asm/arch/gpio.h>
#include <asm/arch/hardware.h>
#endif
#include "plat_ioctl.h"

/* ===========================================================================
* S3C24XX device driver common macro definition
*===========================================================================*/

#define ENPULLUP 1
#define DISPULLUP 0

#define HIGHLEVEL 1
#define LOWLEVEL 0

#define INPUT 1
#define OUTPUT 0

#define OFF 0
#define ON 1

#define ENABLE 1
#define DISABLE 0

#define TRUE 1
#define FALSE 0

/* ===========================================================================
* S3C24XX device driver name and Major number define
*===========================================================================*/

#define DEV_LED_NAME "led"
#define DEV_LED_MAJOR 203

#define DEV_BUTTON_NAME "button"
#define DEV_BUTTON_MAJOR "211"

#define DEV_ADC_NAME "adc"
#define DEV_ADC_MAJOR "212"

/* ***** Bit Operate Define *****/
#define SET_BIT(data, i) ((data) |= (1 << (i))) /* Set the bit "i" in "data" to 1 */
#define CLR_BIT(data, i) ((data) &= ~(1 << (i))) /* Clear the bit "i" in "data" to 0 */
#define NOT_BIT(data, i) ((data) ^= (1 << (i))) /* Inverse the bit "i" in "data" */
#define GET_BIT(data, i) ((data) >> (i) & 1) /* Get the value of bit "i" in "data" */
#define L_SHIFT(data, i) ((data) << (i)) /* Shift "data" left for "i" bit */
#define R_SHIFT(data, i) ((data) >> (i)) /* Shift "data" Right for "i" bit */

/* ===========================================================================
* S3C24XX device driver common function definition
*===========================================================================*/

#define SLEEP(x) {DECLARE_WAIT_QUEUE_HEAD (stSleep); if (10 > x) mdelay ((x * 1000));
else wait_event_interruptible_timeout (stSleep, 0, (x / 10));}

#define VERSION_CODE(a,b,c) ( ((a)<<16) + ((b)<<8) + (c))
#define DRV_VERSION VERSION_CODE(DRV_MAJOR_VER, DRV_MINOR_VER, DRV_REVER_VER)
#define MAJOR_VER(a) ((a)>>16&0xFF)
#define MINOR_VER(a) ((a)>>8&0xFF)
#define REVER_VER(a) ((a)&0xFF)

#define dbg_print(format,args...) if(DISABLE!=debug)
{printk("[kernel] ");printk(format, ##args);}

static inline void print_version(int version)
{
#ifdef __KERNEL__
printk("%d.%d.%d ", MAJOR_VER(version), MINOR_VER(version), REVER_VER(version));
#else
printf("%d.%d.%d ", MAJOR_VER(version), MINOR_VER(version), REVER_VER(version));
#endif
}

#endif /* __S3C_DRIVER_H */

plat_ioctl.h头文件:

/*********************************************************************************
* Copyright(c) 2011, Guo Wenxue <guowenxue@gmail.com>
* All ringhts reserved.
*
* Filename: s3c_ioctl.h
* Description: ioctl() cmd argument definition here
*
* ChangLog:
* 1, Version: 1.0.0
* Date: 2011-08-10
* Author: guowenxue <guowenxue@gmail.com>
* Descrtipion: Initial first version
*
*
********************************************************************************/

#ifndef __PLAT_IOCTL_H
#define __PLAT_IOCTL_H

#include <asm/ioctl.h>

/*===========================================================================
* Common ioctl command definition
*===========================================================================*/

#define PLATDRV_MAGIC 0x60

/*===========================================================================
* ioctl command for all the drivers 0x01~0x0F
*===========================================================================*/

/*args is enable or disable*/
#define SET_DRV_DEBUG _IO (PLATDRV_MAGIC, 0x01)
#define GET_DRV_VER _IO (PLATDRV_MAGIC, 0x02)

/*===========================================================================
* ioctl command for few ioctl() cmd driver 0x10~0x2F
*===========================================================================*/

/* LED driver */
#define LED_OFF _IO (PLATDRV_MAGIC, 0x18)
#define LED_ON _IO (PLATDRV_MAGIC, 0x19)
#define LED_BLINK _IO (PLATDRV_MAGIC, 0x1A)
#define ADC_SET_CHANNEL _IO (PLATDRV_MAGIC, 0x1B)

/*===========================================================================
* ioctl command for GPRS driver 0x30~0x4F
*===========================================================================*/
#define GPRS_POWERDOWN _IO (PLATDRV_MAGIC, 0x30)
#define GPRS_POWERON _IO (PLATDRV_MAGIC, 0x31)
#define GPRS_RESET _IO (PLATDRV_MAGIC, 0x32)
#define GPRS_POWERMON _IO (PLATDRV_MAGIC, 0x33)
#define GPRS_CHK_SIMDOOR _IO (PLATDRV_MAGIC, 0x36)
#define GPRS_SET_DTR _IO (PLATDRV_MAGIC, 0x37)
#define GPRS_SET_RTS _IO (PLATDRV_MAGIC, 0x38)
#define GPRS_GET_RING _IO (PLATDRV_MAGIC, 0x39)
#define SET_PWUP_TIME _IO (PLATDRV_MAGIC, 0x3A)
#define SET_PWDOWN_TIME _IO (PLATDRV_MAGIC, 0x3B)
#define SET_RESET_TIME _IO (PLATDRV_MAGIC, 0x3C)
#define GPRS_CHK_MODEL _IO (PLATDRV_MAGIC, 0x3E)

/*===========================================================================
* ioctl command for EEPROM driver 0x50~0x5F
*===========================================================================*/

#define LL_POWEROFF _IO (PLATDRV_MAGIC, 0x50)
#define LL_POWERON _IO (PLATDRV_MAGIC, 0x51)
#define LL_STOP _IO (PLATDRV_MAGIC, 0x52)
#define LL_START _IO (PLATDRV_MAGIC, 0x53)
#define LL_READ _IO (PLATDRV_MAGIC, 0x54)
#define LL_WRITE _IO (PLATDRV_MAGIC, 0x55)
#define LL_DATALOW _IO (PLATDRV_MAGIC, 0x56)
#define LL_ACKNAK _IO (PLATDRV_MAGIC, 0x57)

#endif /* __PLAT_IOCTL_H */

Makefil文件：

ARCH=arm920t
PROJ=fl2440
PWD=$(shell pwd)

ifneq ("${ARCH}", "x86")
CROSS_COMPILE ?= /opt/buildroot-2011.11/${ARCH}/usr/bin/arm-linux-   /*指定交叉编译器*/
KERNEL_DIR = ../../kernel/linux-3.8/       /*指定内核路径*/
else
KERNEL_DIR = /lib/modules/$(shell uname -r)/build
endif

obj-m += plat_led.o

all:
make -C $(KERNEL_DIR) SUBDIRS=$(PWD) modules
@make clear

clear:
@rm -f *.o *.cmd *.mod.c
@rm -rf *~ core .depend .tmp_versions Module.symvers modules.order -f
@rm -f .*ko.* *ko.* .*.o.cmd

clean:
rm -f *.ko *.o

led测试程序：
/*********************************************************************************
 *      Copyright:  (C) 2014 zhouguangfeng<zhouguangfeng91@gmail.com>
 *                  All rights reserved.
 *
 *       Filename:  test_plat_led.c
 *    Description:  This file is used to test led platform drvier
 *                 
 *        Version:  1.0.0(08/25/2014)
 *         Author:  zhouguangfeng <zhouguangfeng91@gmail.com>
 *      ChangeLog:  1, Release initial version on "08/25/2014 04:04:26 PM"
 *                 
 ********************************************************************************/
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>

#define PLATDRV_MAGIC           0x60

#define LED_OFF                     _IO (PLATDRV_MAGIC, 0x18)
#define LED_ON                      _IO (PLATDRV_MAGIC, 0x19)
#define LED_BLINK                   _IO (PLATDRV_MAGIC, 0x1A)



/********************************************************************************
 *  Description:
 *   Input Args:
 *  Output Args:
 * Return Value:
 ********************************************************************************/
int main (int argc, char **argv)
{
    int fd;
    int i;

    fd = open("/dev/led", O_RDWR, 0755);
    if(fd<0)
    {
        printf("cannot open.
");
        goto open_err;
    }

    ioctl(fd, LED_BLINK, 0);
    ioctl(fd, LED_OFF, 1);
    ioctl(fd, LED_ON, 2);
    ioctl(fd, LED_OFF, 3);

open_err:
    close(fd);
    return 0;
} /* ----- End of main() ----- */