分層分離而來，用QT6410實踐

本例為點亮LED：

最簡單的led驅動就是從埠輸出0或1來關閉或點亮燈。而我們這裡講的led子系統，主要是對led事件進行了分裝和優化，這裡我們主要講的是可以實現跨平臺的led驅動。不管你是使用三星的平臺，還是Atmel的平臺，你只要知道如何在你的BSP中新增平臺數據，並且知道如何在應用程式中使用這個驅動，那麼你就不用因為新的平臺而再次編寫led驅動。

程式碼如下：

led_dev.c

#include <linux/module.h>
#include <linux/version.h>

#include <linux/init.h>

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <linux/serial_core.h>
#include <linux/platform_device.h>


/* 分配/設定/註冊一個platform_device */

static struct resource led_resource[] = {
    [0] = {
        .start = 0x7F008820,
        .end   = 0x7F008820 + 16 - 1,
        .flags = IORESOURCE_MEM,
    },
    [1] = {
        .start = 0,
        .end   = 0,
        .flags = IORESOURCE_IRQ,
    }

};

static void led_release(struct device * dev)
{
}


static struct platform_device led_dev = {
    .name         = "myled",
    .id       = -1,
    .num_resources    = ARRAY_SIZE(led_resource),
    .resource     = led_resource,
    .dev = { 
    	.release = led_release, 
	},
};

static int led_dev_init(void)
{
	platform_device_register(&led_dev);
	return 0;
}

static void led_dev_exit(void)
{
	platform_device_unregister(&led_dev);
}

module_init(led_dev_init);
module_exit(led_dev_exit);

MODULE_LICENSE("GPL");
 

led_drv.c

/* 分配/設定/註冊一個platform_driver */

#include <linux/module.h>
#include <linux/version.h>

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/sched.h>
#include <linux/pm.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/input.h>
#include <linux/irq.h>
#include <asm/uaccess.h>
#include <asm/io.h>

static int major;


static struct class *cls;
static struct class_device *led_cls;
static volatile unsigned long *gpio_con;
static volatile unsigned long *gpio_dat;
static int pin;

static int led_open(struct inode *inode, struct file *file)
{
	//printk("first_drv_open\n");
	/* 配置為輸出 */
	*gpio_con &= ~(0xf<<(pin*4));
	*gpio_con |= (0x1<<(pin*4));
	return 0;	
}

static ssize_t led_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
	int val;

	//printk("first_drv_write\n");

	copy_from_user(&val, buf, count); //	copy_to_user();

	if (val == 1)
	{
		// 點燈
		*gpio_dat &= ~(1<<pin);
	}
	else
	{
		// 滅燈
		*gpio_dat |= (1<<pin);
	}
	
	return 0;
}


static struct file_operations led_fops = {
    .owner  =   THIS_MODULE,    /* 這是一個巨集，推向編譯模組時自動建立的__this_module變數 */
    .open   =   led_open,     
	.write	=	led_write,	   
};

static int led_probe(struct platform_device *pdev)
{
	struct resource		*res;

	/* 根據platform_device的資源進行ioremap */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	gpio_con = ioremap(res->start, res->end - res->start + 1);
	gpio_dat = gpio_con + 1;

	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	pin = res->start;

	/* 註冊字元裝置驅動程式 */

	printk("led_probe, found led\n");

	major = register_chrdev(0, "myled", &led_fops);

	cls = class_create(THIS_MODULE, "myled");

	led_cls = device_create(cls, NULL, MKDEV(major, 0), NULL, "led"); /* /dev/led */
	
	return 0;
}

static int led_remove(struct platform_device *pdev)
{
	/* 解除安裝字元裝置驅動程式 */
	/* iounmap */
	printk("led_remove, remove led\n");

	device_unregister(led_cls);
	class_destroy(cls);
	unregister_chrdev(major, "myled");
	iounmap(gpio_con);
	
	return 0;
}


struct platform_driver led_drv = {
	.probe		= led_probe,
	.remove		= led_remove,
	.driver		= {
		.name	= "myled",
	}
};


static int led_drv_init(void)
{
	platform_driver_register(&led_drv);
	return 0;
}

static void led_drv_exit(void)
{
	platform_driver_unregister(&led_drv);
}

module_init(led_drv_init);
module_exit(led_drv_exit);

MODULE_LICENSE("GPL");



 

Makefile:

KERN_DIR = /work/work/linux

all:
	make -C $(KERN_DIR) M=`pwd` modules 
	cp *.ko /work/nfsroot
	

clean:
	make -C $(KERN_DIR) M=`pwd` modules clean
	

obj-m	+= led_drv.o
obj-m	+= led_dev.o

led_test.c

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <stdio.h>



/* led_test on

 * led_test off

 */

int main(int argc, char **argv)

{

	int fd;

	int val = 1;

	fd = open("/dev/led", O_RDWR);

	if (fd < 0)

	{

		printf("can't open!\n");

	}

	if (argc != 2)

	{

		printf("Usage :\n");

		printf("%s <on|off>\n", argv[0]);

		return 0;

	}



	if (strcmp(argv[1], "on") == 0)

	{

		val  = 1;

	}

	else

	{

		val = 0;

	}

	

	write(fd, &val, 4);

	return 0;

}
 

執行

 ./led_test on

時點亮第一盞燈；

執行

 ./led_test off

時熄滅第一盞燈；