Linux驱动----使用probe和不使用probe

不使用probe的字符设备，实例程序如下图

module_init(myled_init); 代表驱动的入口函数
module_exit(myled_exit); 代表驱动的出口函数

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>

#define S3C2440_GPA(n)  (0<<16 | n)
#define S3C2440_GPB(n)  (1<<16 | n)
#define S3C2440_GPC(n)  (2<<16 | n)
#define S3C2440_GPD(n)  (3<<16 | n)
#define S3C2440_GPE(n)  (4<<16 | n)
#define S3C2440_GPF(n)  (5<<16 | n)
#define S3C2440_GPG(n)  (6<<16 | n)
#define S3C2440_GPH(n)  (7<<16 | n)
#define S3C2440_GPI(n)  (8<<16 | n)
#define S3C2440_GPJ(n)  (9<<16 | n)

static int led_pin = S3C2440_GPF(5);
static volatile unsigned int *gpio_con;
static volatile unsigned int *gpio_dat;

/* 123. 分配/设置/注册file_operations 
 * 4. 入口
 * 5. 出口
 */

static int major;
static struct class *led_class;

static unsigned int gpio_base[] = {
	0x56000000, /* GPACON */
	0x56000010, /* GPBCON */
	0x56000020, /* GPCCON */
	0x56000030, /* GPDCON */
	0x56000040, /* GPECON */
	0x56000050, /* GPFCON */
	0x56000060, /* GPGCON */
	0x56000070, /* GPHCON */
	0,          /* GPICON */
	0x560000D0, /* GPJCON */
};

static int led_open (struct inode *node, struct file *filp)
{
	/* 把LED引脚配置为输出引脚 */
	/* GPF5 - 0x56000050 */
	int bank = led_pin >> 16;
	int base = gpio_base[bank];

	int pin = led_pin & 0xffff;
	gpio_con = ioremap(base, 8);
	if (gpio_con) {
		printk("ioremap(0x%x) = 0x%x\n", base, gpio_con);
	}
	else {
		return -EINVAL;
	}
	
	gpio_dat = gpio_con + 1;

	*gpio_con &= ~(3<<(pin * 2));
	*gpio_con |= (1<<(pin * 2));  

	return 0;
}

static ssize_t led_write (struct file *filp, const char __user *buf, size_t size, loff_t *off)
{
	/* 根据APP传入的值来设置LED引脚 */
	unsigned char val;
	int pin = led_pin & 0xffff;
	
	copy_from_user(&val, buf, 1);

	if (val)
	{
		/* 点灯 */
		*gpio_dat &= ~(1<<pin);
	}
	else
	{
		/* 灭灯 */
		*gpio_dat |= (1<<pin);
	}

	return 1; /* 已写入1个数据 */
}

static int led_release (struct inode *node, struct file *filp)
{
	printk("iounmap(0x%x)\n", gpio_con);
	iounmap(gpio_con);
	return 0;
}


static struct file_operations myled_oprs = {
	.owner = THIS_MODULE,
	.open  = led_open,
	.write = led_write,
	.release = led_release,
};


static int myled_init(void)
{
	major = register_chrdev(0, "myled", &myled_oprs);

	led_class = class_create(THIS_MODULE, "myled");
	device_create(led_class, NULL, MKDEV(major, 0), NULL, "led"); /* /dev/led */

	return 0;
}

static void myled_exit(void)
{
	unregister_chrdev(major, "myled");
	device_destroy(led_class,  MKDEV(major, 0));
	class_destroy(led_class);
}

module_init(myled_init);
module_exit(myled_exit);


MODULE_LICENSE("GPL");

如果使用平台设备驱动，则需要probe函数，驱动分为device和driver两部分，最终由平台设备总线Platform的match匹配，生成设备文件节点。

device程序为：

#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>

#define S3C2440_GPA(n)  (0<<16 | n)
#define S3C2440_GPB(n)  (1<<16 | n)
#define S3C2440_GPC(n)  (2<<16 | n)
#define S3C2440_GPD(n)  (3<<16 | n)
#define S3C2440_GPE(n)  (4<<16 | n)
#define S3C2440_GPF(n)  (5<<16 | n)
#define S3C2440_GPG(n)  (6<<16 | n)
#define S3C2440_GPH(n)  (7<<16 | n)
#define S3C2440_GPI(n)  (8<<16 | n)
#define S3C2440_GPJ(n)  (9<<16 | n)


/* 分配/设置/注册一个platform_device */

static struct resource led_resource[] = {
    [0] = {
        .start = S3C2440_GPF(5),
        .end   = S3C2440_GPF(5),
        .flags = IORESOURCE_MEM,
    },
};

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");

driver程序为：

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>

#define S3C2440_GPA(n)  (0<<16 | n)
#define S3C2440_GPB(n)  (1<<16 | n)
#define S3C2440_GPC(n)  (2<<16 | n)
#define S3C2440_GPD(n)  (3<<16 | n)
#define S3C2440_GPE(n)  (4<<16 | n)
#define S3C2440_GPF(n)  (5<<16 | n)
#define S3C2440_GPG(n)  (6<<16 | n)
#define S3C2440_GPH(n)  (7<<16 | n)
#define S3C2440_GPI(n)  (8<<16 | n)
#define S3C2440_GPJ(n)  (9<<16 | n)

static int led_pin;
static volatile unsigned int *gpio_con;
static volatile unsigned int *gpio_dat;

/* 123. 分配/设置/注册file_operations 
 * 4. 入口
 * 5. 出口
 */

static int major;
static struct class *led_class;

static unsigned int gpio_base[] = {
	0x56000000, /* GPACON */
	0x56000010, /* GPBCON */
	0x56000020, /* GPCCON */
	0x56000030, /* GPDCON */
	0x56000040, /* GPECON */
	0x56000050, /* GPFCON */
	0x56000060, /* GPGCON */
	0x56000070, /* GPHCON */
	0,          /* GPICON */
	0x560000D0, /* GPJCON */
};

static int led_open (struct inode *node, struct file *filp)
{
	/* 把LED引脚配置为输出引脚 */
	/* GPF5 - 0x56000050 */
	int bank = led_pin >> 16;
	int base = gpio_base[bank];

	int pin = led_pin & 0xffff;
	gpio_con = ioremap(base, 8);
	if (gpio_con) {
		printk("ioremap(0x%x) = 0x%x\n", base, gpio_con);
	}
	else {
		return -EINVAL;
	}
	
	gpio_dat = gpio_con + 1;

	*gpio_con &= ~(3<<(pin * 2));
	*gpio_con |= (1<<(pin * 2));  

	return 0;
}

static ssize_t led_write (struct file *filp, const char __user *buf, size_t size, loff_t *off)
{
	/* 根据APP传入的值来设置LED引脚 */
	unsigned char val;
	int pin = led_pin & 0xffff;
	
	copy_from_user(&val, buf, 1);

	if (val)
	{
		/* 点灯 */
		*gpio_dat &= ~(1<<pin);
	}
	else
	{
		/* 灭灯 */
		*gpio_dat |= (1<<pin);
	}

	return 1; /* 已写入1个数据 */
}

static int led_release (struct inode *node, struct file *filp)
{
	printk("iounmap(0x%x)\n", gpio_con);
	iounmap(gpio_con);
	return 0;
}


static struct file_operations myled_oprs = {
	.owner = THIS_MODULE,
	.open  = led_open,
	.write = led_write,
	.release = led_release,
};


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

	/* 根据platform_device的资源进行ioremap */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	led_pin = res->start;

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

	led_class = class_create(THIS_MODULE, "myled");
	device_create(led_class, NULL, MKDEV(major, 0), NULL, "led"); /* /dev/led */
	
	return 0;
}

static int led_remove(struct platform_device *pdev)
{
	unregister_chrdev(major, "myled");
	device_destroy(led_class,  MKDEV(major, 0));
	class_destroy(led_class);
	
	return 0;
}


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


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

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

module_init(myled_init);
module_exit(myled_exit);


MODULE_LICENSE("GPL");

与不调用probe函数相比，入口函数myled_init调用的是platform_driver_register(&led_drv)，此时调用的是平台设备驱动结构体

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

在probe函数中，首先调用platform_get_resource(pdev, IORESOURCE_MEM, 0)获取底层device的硬件资源，然后再去去分配、设置、注册 file_operations。

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

	/* 根据platform_device的资源进行ioremap */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	led_pin = res->start;

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

	led_class = class_create(THIS_MODULE, "myled");
	device_create(led_class, NULL, MKDEV(major, 0), NULL, "led"); /* /dev/led */
	
	return 0;
}

此文章结合韦东山老师讲解视频编写而成。

Linux驱动----使用probe和不使用probe

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