十 編寫LED驅動程式

結合前面介紹的linux字元驅動編寫的流程（申請裝置號-裝置註冊-生成裝置節點），開始對led驅動進行編寫。編寫驅動的流程：檢視原理圖以及資料手冊-核心尋找相似驅動進行開發，有時從零開始-字元驅動編寫以及實現功能，方便呼叫-編譯核心或者insmod載入-測試驅動。

檢視原理圖以及資料手冊（如下圖），從圖中可以看出kp_col0和vdd50_en控制led的點亮。

當kp_col0 和vdd50_en 網路時高電平的時候，三極體l9014 的be 導通，ce 導通，相當於5v 的vsys 電壓加到1k 和led 小燈上，小燈就會亮；當kp_col0 和vdd50_en 網路時低電平的時候，三極體l9014 的be 會截止，ce 截止，相當於5v 的vsys 電壓加到1k、led 小燈和乙個無限大的電阻上，電流為零，小燈就會滅。

從上圖可以看出led巨集定義為exynos4_gpl2(0)，exynos4_gpk1(1)。

標頭檔案char_driver.h

#ifndef _char_driver_leds_h_

#define _char_driver_leds_h_
#ifndef device_name
#define device_name "chdriver"
#endif
#ifndef device_minor_num
#define device_minor_num 2
#endif
#ifndef dev_major
#define dev_major 0
#endif
#ifndef dev_minor
#define dev_minor 0
#endif
#ifndef regdev_size
#define regdev_size 3000
#endif
struct reg_dev
;#endif

#include 

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include "char_driver.h"
module_license("dual bsd/gpl");
module_author("flywang");
static
int led_gpios = ;
#define led_num     array_size(led_gpios)
int numdev_major = dev_major;
int numdev_minor = dev_minor;
module_param(numdev_major,int,s_irusr);
module_param(numdev_minor,int,s_irusr);
static
struct
class *myclass;
struct reg_dev *my_devices;
static
int chardevnode_open(struct inode *inode, struct file *file)
/*關閉操作*/
static
int chardevnode_release(struct inode *inode, struct file *file)
/*io操作*/
static
long chardevnode_ioctl(struct file *file, unsigned
int cmd, unsigned
long arg)
gpio_set_value(led_gpios[arg], cmd);
break;
default:
return -einval;
}printk(kern_emerg "chardevnode_ioctl is success! cmd is %d,arg is %d \n",cmd,arg);
return0;}
ssize_t chardevnode_read(struct file *file, char __user *buf, size_t count, loff_t *f_ops)
ssize_t chardevnode_write(struct file *file, const
char __user *buf, size_t count, loff_t *f_ops)
loff_t chardevnode_llseek(struct file *file, loff_t offset, int ence)
struct file_operations my_fops = ;
/*裝置註冊到系統*/
static
void reg_init_cdev(struct reg_dev *dev,int index)
else
}static
int gpio_init(void)
else
}return0;}
static
int led_init(void)
else
if(ret<0)
myclass = class_create(this_module,device_name);
my_devices = kmalloc(device_minor_num * sizeof(struct reg_dev),gfp_kernel);
if(!my_devices)
memset(my_devices,0,device_minor_num * sizeof(struct reg_dev));
/*裝置初始化*/
for(i=0;imemset(my_devices[i].data,0,regdev_size);
/*裝置註冊到系統*/
reg_init_cdev(&my_devices[i],i);
device_create(myclass,null,     mkdev(numdev_major,numdev_minor+i),
null,device_name"%d",i);
}ret = gpio_init();
if(ret)   
printk(kern_emerg "scdev_init!\n");
return
0;fail:
/*登出裝置號*/
unregister_chrdev_region(mkdev(numdev_major,numdev_minor),device_minor_num);
printk(kern_emerg "kmalloc is fail!\n");
return ret;
}static
void led_exit(void)
else
close(fd);
}

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