linux led驱动,lcd背光驱动

led 驱动，lcd背光驱动，仿照杨创提供的驱动，写成misc 驱动。lcd 背光驱动的本质上也是个led 驱动。

/*
 *  LED  interface	driver for utu2440
 *
 * 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.
 *
 *	[email protected]
 */



#include <linux/types.h>
#include <linux/ioport.h>
#include <linux/fcntl.h>
#include <linux/miscdevice.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/arch/regs-gpio.h>

#define LED_DRIVER	"utu2440 LED Driver v1.00"

static unsigned long led_table [] = {
	S3C2410_GPF4,
	S3C2410_GPF5,
	S3C2410_GPF6,
	S3C2410_GPF7,
};

static int led_ioctl(struct inode *inode, struct file *file,
		     unsigned int cmd, unsigned long arg);

static int led_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);
	default:
		return -EINVAL;
	}
	return 0;
}

static struct file_operations led_fops = {
	.ioctl = led_ioctl,
};

static struct miscdevice led_dev = {
	MISC_DYNAMIC_MINOR,
	"myled",
	&led_fops
};

static int led_init(void)
{
	pr_info("%s\n", LED_DRIVER);
	misc_register(&led_dev);
	return 0;
}

static void __exit led_exit(void)
{
	misc_deregister(&led_dev);
}

module_init(led_init);
module_exit(led_exit);

MODULE_AUTHOR("[email protected]");
MODULE_LICENSE("GPL");

#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/init.h>
#include <linux/serio.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/miscdevice.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#include <mach/regs-clock.h>
#include <plat/regs-timer.h>
#include <mach/regs-gpio.h>
#include <linux/cdev.h>

#define DEVICE_NAME "backlight" //设备名称
#define DEVICE_MINOR 5 //次设备号，这里我们将设备注册为misc设备，这种设备的主设备号都为10

static int my2440_backlight_ioctl(struct inode *inode, 

                                  struct file *file, 

                                  unsigned int cmd, 

                                  unsigned long arg)
{
    switch(cmd)
    {
        case 0:

            //当接收的命令为0时，就将GPG4引脚设为低电平，关闭背光
            s3c2410_gpio_setpin(S3C2410_GPG4, 0); 
            printk(DEVICE_NAME " turn off!\n");
            return 0;
        case 1:

            //当接收的命令为1时，就将GPG4引脚设为高电平，开启背光
            s3c2410_gpio_setpin(S3C2410_GPG4, 1); 
            printk(DEVICE_NAME " turn on!\n");
            return 0;
        default:
            return -EINVAL;
    }
}

static struct file_operations dev_fops = 
{
    .owner = THIS_MODULE,
    .ioctl = my2440_backlight_ioctl, //这里只使用控制IO口的方式来控制背光
};

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

static int __init dev_init(void)
{
    int ret;

    ret = misc_register(&misc); //注册成misc设备

    if(ret < 0)
    {
        printk("Register misc device fiald!");
        return ret;
    }


    //将GPG4口配置成输出口
    s3c2410_gpio_cfgpin(S3C2410_GPG4, S3C2410_GPG4_OUTP); 

    return ret;
}

static void __exit dev_exit(void)
{
    misc_deregister(&misc); //注销该misc设备
}

module_init(dev_init);
module_exit(dev_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("xzf");
MODULE_DESCRIPTION("Backlight control for my2440");

 

分析如下

1.数据结构

  a.miscdevice,混杂设备，里面做了很多标准字符设备的封装

     这里直接申明led_dev使用，填充三个数据，次设备号，设备名称，驱动操作

   b.led 信息，这里用到了一个数组，与平台相关。

  c.lcd 背光，直接使用接口操作

2.驱动分析

a.入口，出口。module_init(led_init);module_exit(led_exit);

        led_init做了一件事：将led_dev注册成misc

      led_exit做了一件事：将led_dev从misc注销

b.标准文件驱动编写

   1.文件操作指针结构赋值

    2.完成相应操作