嵌入式Linux之我行——LED驱动在2440上的实例开发

#gedit arch/arm/plat-s3c24xx/common-smdk.c//注释掉以下内容

staticstructplatform_device __initdata*smdk_devs[]={
&s3c_device_nand,

};

void__init smdk_machine_init(void)
{



if(machine_is_smdk2443())
smdk_nand_info.twrph0=50;

s3c_device_nand.dev.platform_data=&smdk_nand_info;

platform_add_devices(smdk_devs,ARRAY_SIZE(smdk_devs));

s3c_pm_init();
}

#include
#include
#include
#include
#include
#include
#include

#define DEVICE_NAME "my2440_leds" //设备名称
#define LED_MAJOR 231 //主设备号
#define LED_ON 1 //LED亮状态
#define LED_OFF 0 //LED灭状态

static unsigned long led_table[] = //控制LED的IO口
{
S3C2410_GPB5,
S3C2410_GPB6,
S3C2410_GPB7,
S3C2410_GPB8,
};

static unsigned int led_cfg_table[] = //LED IO口的模式
{
S3C2410_GPB5_OUTP,
S3C2410_GPB6_OUTP,
S3C2410_GPB7_OUTP,
S3C2410_GPB8_OUTP,
};

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

static int leds_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
//检测是第几个LED，因开发板上只有4个，索引从0开始
if(arg < 0 || arg > 3)
{
return -EINVAL;
}

//判断LED要执行哪种状态
switch(cmd)
{
case LED_ON:
{
s3c2410_gpio_setpin(led_table[arg], ~(LED_ON));
break;
}
case LED_OFF:
{
s3c2410_gpio_setpin(led_table[arg], ~(LED_OFF));
break;
}
default:
{
return -EINVAL;
}
}

return 0;
}

static struct file_operations leds_fops =
{
.owner = THIS_MODULE,
.open = leds_open,
.ioctl = leds_ioctl,
};

static int __init led_init(void)
{
int ret, i;

for(i = 0; i < 4; i++)
{
//初始化各IO口为输出模式
s3c2410_gpio_cfgpin(led_table[i], led_cfg_table[i]);

//由原理图可知LED电路是共阳极的(即各IO口输出低电平0才会点亮)
//这里初始化为1，不让LED点亮
s3c2410_gpio_setpin(led_table[i], ~(LED_OFF));
}

//注册LED设备为字符设备
ret = register_chrdev(LED_MAJOR, DEVICE_NAME, &leds_fops);

if(ret < 0)
{
printk(DEVICE_NAME " register falid!n");
return ret;
}
}

static void __exit led_exit(void)
{
//注销设备
unregister_chrdev(LED_MAJOR, DEVICE_NAME);
}

module_init(led_init);
module_exit(led_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Huang Gang");
MODULE_DESCRIPTION("My2440 led driver");

#cp -f my2440_leds.c /linux-2.6.30.4/drivers/char//把驱动源码复制到内核驱动的字符设备下

#gedit /linux-2.6.30.4/drivers/char/Kconfig//添加LED设备配置

config MY2440_LEDS
tristate "My2440 Leds Device"
depends on ARCH_S3C2440
default y
---help---
My2440 User Leds

#gedit /linux-2.6.30.4/drivers/char/Makefile//添加LED设备配置

obj-$(CONFIG_MY2440_LEDS)+= my2440_leds.o

#make menuconfig

Device Drivers --->
Character devices --->
<*>My2440 Leds Device (NEW)

#include
#include
#include
#include

int main(int argc, char **argv)
{
int turn, index, fd;

//检测输入的参数合法性
if(argc != 3 || sscanf(argv[2], "%d", &index) != 1 || index < 1 || index > 4)
{
printf("Usage: leds_test on|off 1|2|3|4n");
exit(1);
}

if(strcmp(argv[1], "on") == 0)
{
turn = 1;
}
else if(strcmp(argv[1], "off") == 0)
{
turn = 0;
}
else
{
printf("Usage: leds_test on|off 1|2|3|4n");
exit(1);
}

//打开LED设备
fd = open("/dev/my2440_leds", 0);

if(fd < 0)
{
printf("Open Led Device Faild!n");
exit(1);
}

//IO控制
ioctl(fd, turn, index - 1);

//关闭LED设备
close(fd);

return 0;
}

#arm-linux-gcc -o leds_test leds_test.c