RTC驱动模型分析

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static struct resource s3c_rtc_resource[] = {
	[0] = {
		.start = S3C24XX_PA_RTC,
		.end   = S3C24XX_PA_RTC + 0xff,
		.flags = IORESOURCE_MEM,
	},
	[1] = {
		.start = IRQ_RTC,
		.end   = IRQ_RTC,
		.flags = IORESOURCE_IRQ,
	},
	[2] = {
		.start = IRQ_TICK,
		.end   = IRQ_TICK,
		.flags = IORESOURCE_IRQ
	}
};
struct platform_device s3c_device_rtc = {
	.name		  = "s3c2410-rtc",
	.id		  = -1,
	.num_resources	  = ARRAY_SIZE(s3c_rtc_resource),
	.resource	  = s3c_rtc_resource,  //##
};

static struct platform_device *tq2440_devices[] __initdata = {
	......,
	&s3c_device_rtc, //##
	......,
};

platform_add_devices(tq2440_devices, ARRAY_SIZE(tq2440_devices));//注意：是platform_add_devices是通过for循环调用platform_devices_add()函数
//通过这个函数就把这个数组里边所有的设备资源都注册到了platform设备总线下

static struct platform_driver s3c2410_rtc_driver = {
	.probe		= s3c_rtc_probe,
	......
	.driver		= {
		.name	= "s3c2410-rtc",
		.owner	= THIS_MODULE,
	},
};

return platform_driver_register(&s3c2410_rtc_driver);//这样就把RTC驱动注册到platform总线上去了

s3c_rtc_probe(struct platform_device *pdev)
{
	......
	s3c_rtc_tickno = platform_get_irq(pdev, 1);
	......
	s3c_rtc_alarmno = platform_get_irq(pdev, 0);
	......
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	......
	s3c_rtc_base = ioremap(res->start, res->end - res->start + 1);
	......
	s3c_rtc_enable(pdev, 1);
	......
	s3c_rtc_setfreq(&pdev->dev, 1);
	......
	rtc = rtc_device_register("s3c", &pdev->dev, &s3c_rtcops,THIS_MODULE);//【进去分析】
}

rtc_device_register(const char *name, struct device *dev,const struct rtc_class_ops *ops,struct module *owner)
{
	struct rtc_device *rtc;
	......
	//①申请这么一个结构体往后就初始化他的成员
	rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
	......
	rtc->id = id;
	rtc->ops = ops;
	rtc->owner = owner;
	rtc->max_user_freq = 64;
	rtc->dev.parent = dev;
	rtc->dev.class = rtc_class;
	rtc->dev.release = rtc_device_release;
	......
	rtc_dev_prepare(rtc);//这个函数在/drivers/rtc/rtc-dev.c:定义
	//②把这个结构的dev结构成员往上注册
	err = device_register(&rtc->dev); //这个函数最终就是调用device_add(&pdev->dev);
	......
	rtc_dev_add_device(rtc);
	rtc_sysfs_add_device(rtc);
	rtc_proc_add_device(rtc);
	......
}

struct rtc_device
{
	struct device dev;
	struct module *owner;
	int id;
	char name[RTC_DEVICE_NAME_SIZE];
	.......
	const struct rtc_class_ops *ops; //##
	struct mutex ops_lock;
	.......
	struct cdev char_dev;
	unsigned long flags;
	int max_user_freq;
}

static const struct rtc_class_ops s3c_rtcops = {
	.open		= s3c_rtc_open,
	.release	= s3c_rtc_release,
	.read_time	= s3c_rtc_gettime,
	.set_time	= s3c_rtc_settime,
	.read_alarm	= s3c_rtc_getalarm,
	.set_alarm	= s3c_rtc_setalarm,
	.irq_set_freq	= s3c_rtc_setfreq,
	.irq_set_state	= s3c_rtc_setpie,
	.proc	        = s3c_rtc_proc,
};

static const struct file_operations rtc_dev_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.read		= rtc_dev_read,
	.poll		= rtc_dev_poll,
	.unlocked_ioctl	= rtc_dev_ioctl,//**ioctl()函数里边命令的响应函数在/drivers/rtc/intreface.c中定义
	.open		= rtc_dev_open,
	.release	= rtc_dev_release,
	.fasync		= rtc_dev_fasync,
};

rtc_dev_prepare(struct rtc_device *rtc)
{
	......
	rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
	......
	cdev_init(&rtc->char_dev, &rtc_dev_fops);//在这里被用来注册字符设备
	rtc->char_dev.owner = rtc->owner;
}

rtc_device_register(const char *name, struct device *dev,const struct rtc_class_ops *ops,struct module *owner)
{
	struct rtc_device *rtc;
	......
	//①申请这么一个结构体往后就初始化他的成员
	rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
	......
	rtc->id = id;
	rtc->ops = ops;
	......
	rtc->dev.class = rtc_class;
	......
	rtc_dev_prepare(rtc);//##
	//②把这个结构的dev结构成员往上注册
	err = device_register(&rtc->dev); //这个函数最终就是调用device_add(&pdev->dev);
	......
	rtc_dev_add_device(rtc);
	......
}

rtc_device_register(const char *name, struct device *dev,const struct rtc_class_ops *ops,struct module *owner)
{
	struct rtc_device *rtc;
	......
	//①申请这么一个结构体往后就初始化他的成员
	rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
	......
	rtc->ops = ops;
	......
	rtc->dev.class = rtc_class;
	rtc_dev_prepare(rtc);//这个函数在最终完成字符设备的注册
	//②从根源的角度来说以下就是probe函数最终多做的事情
	err = device_register(&rtc->dev); //这个函数最终就是调用device_add(&pdev->dev);
	......
	rtc_dev_add_device(rtc);
	rtc_sysfs_add_device(rtc);
	rtc_proc_add_device(rtc);
	......
}

rtc_init(void)
{
	rtc_class = class_create(THIS_MODULE, "rtc"); /* 创建了一个类--rtc */
	......
	rtc_class->suspend = rtc_suspend;
	rtc_class->resume = rtc_resume;
	rtc_dev_init(); /* 为RTC设备动态分配设备号 */
	rtc_sysfs_init(rtc_class);
	return 0;
}

error = device_add_class_symlinks(dev);

static int device_add_class_symlinks(struct device *dev)//从函数的名字猜测：在类下创建设备的符号链接文件
{
	int error;
	......
	error = sysfs_create_link(&dev->kobj,&dev->class->p->class_subsys.kobj,"subsystem");//创建链接文件
	......
	class_name = make_class_name(dev->class->name,&dev->kobj);//设置类下的设备名
}

最后来个高度总结

RTC驱动模型分析

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原文地址：http://blog.csdn.net/clb1609158506/article/details/45165539