rtc-core-$（CONFIG_RTC_INTF_DEV） += rtc-dev.o rtc-core-$（CONFIG_RTC_INTF_PROC） += rtc-proc.o rtc-core-$（CONFIG_RTC_INTF_SYSFS） += rtc-sysfs.o下面这些是对应的具体的实现，根据自己的情况进行选择。obj-$（CONFIG_RTC_DRV_RX8581）+= rtc-rx8581.o obj-$（CONFIG_RTC_DRV_S35390A） += rtc-s35390a.o obj-$（CONFIG_RTC_DRV_S3C） += rtc-s3c.o obj-$（CONFIG_RTC_DRV_SA1100） += rtc-sa1100.o 应该能从中看出，rtc的驱动大致和那些文件有关，再看对应的kconfig文件，可以看出对应文件的用途，我们就不列出对应的kconfig文件了，因为内容太多了。2、现在的RTC驱动架构，当然看一下Rtc.txt （linux2.6.28documentation）文件，对我们理解此架构是很有帮助的，列出部分： New portable "RTC Class" drivers: /dev/rtcN -------------------------------------------- Because Linux supports many non-ACPI and non-PC platforms, some of which have more than one RTC style clock, it needed a more portable solution than expecting a single battery-backed MC146818 clone on every system. Accordingly, a new "RTC Class" framework has been defined.讲述了新架构建立的原因。 It offers three different userspace interfaces:讲述了与用户空间的三种接口 * /dev/rtcN ... much the same as the older /dev/rtc interface * /sys/class/rtc/rtcN ... sysfs attributes support readonly access to some RTC attributes. * /proc/driver/rtc ... the first RTC （rtc0） may expose itself using a procfs interface. More information is （currently） shown here than through sysfs. The RTC Class framework supports a wide variety of RTCs, ranging from those integrated into embeddable system-on-chip （SOC） processors to discrete chips using I2C, SPI, or some other bus to communicate with the host CPU. There"s even support for PC-style RTCs ... including the features exposed on newer PCs through ACPI.这种分类的架构，支持更广阔的RTC设备。 The new framework also removes the "one RTC per system" restriction. For example, maybe the low-power battery-backed RTC is a discrete I2C chip, but a high functionality RTC is integrated into the SOC. That system might read the system clock from the discrete RTC, but use the integrated one for all other tasks, because of its greater functionality. The ioctl（） calls supported by /dev/rtc are also supported by the RTC class framework. However, because the chips and systems are not standardized, some PC/AT functionality might not be provided. And in the same way, some newer features -- including those enabled by ACPI -- are exposed by the RTC class framework, but can"t be supported by the older driver. 3、有关文件的作用与RTC核心有关的文件有： （1）、/drivers/rtc/class.c 这个文件向linux设备驱动模型核心注册了一个RTC类，然后向具体的驱动程序提供了rtc_device_register用于注册和rtc_device_unregister用于注销设备。还实现的rtc类设备的注册。列出部分源码：static int __init rtc_init（void） { rtc_class = class_create（THIS_MODULE, "rtc"）; if （IS_ERR（rtc_class）） { printk（KERN_ERR "%s: couldn"t create class
", __FILE__）; return PTR_ERR（rtc_class）; } rtc_class->suspend = rtc_suspend; rtc_class->resume = rtc_resume; rtc_dev_init（）; rtc_sysfs_init（rtc_class）; return 0; } static void __exit rtc_exit（void） { rtc_dev_exit（）; class_destroy（rtc_class）; }
subsys_initcall（rtc_init）; module_exit（rtc_exit）; （2）、/drivers/rtc/rtc-dev.c 这个文件定义了顶层基本的字符设备文件操作函数，如：open,read等，有个结构体，如下所示：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, .open = rtc_dev_open, .release = rtc_dev_release, .fasync = rtc_dev_fasync, };此结构体用于字符设备注册是使用。 （3）、/drivers/rtc/interface.c 这个文件主要提供了用户程序与RTC驱动的接口函数，用户程序一般通过ioctl与RTC驱动交互，这里定义了每个ioctl命令需要调用的函数。看函数名，也能猜出大概：EXPORT_SYMBOL_GPL（rtc_set_time）;EXPORT_SYMBOL_GPL（rtc_read_alarm）; （4）、/drivers/rtc/rtc-sysfs.c 看名字就很清楚，与sysfs有关，看注释：/* * RTC subsystem, sysfs interface */ （5）、/drivers/rtc/rtc-proc.c 与proc文件系统有关，同样：/* * RTC subsystem, proc interface */ （6）、/drivers/rtc/rtc-lib.c 主要和时间转化有关，列出一个函数，看函数名就能看出大概，int rtc_year_days（unsigned int day, unsigned int month, unsigned int year） { return rtc_ydays[LEAP_YEAR（year）][month] + day-1; } （7）、/drivers/rtc/hctosys.c 和系统时钟有关,就一个函数，/* * RTC subsystem, initialize system time on startup */static int __init rtc_hctosys（void） （8）、/include/linux/rtc.h 定义了与RTC有关的数据结构，如下所示：structrtc_class_ops { 用于具体设备的驱动接口 int （*open）（struct device *）; void （*release）（struct device *）; int （*ioctl）（struct device *, unsigned int, unsigned long）; int （*read_time）（struct device *, struct rtc_time *）; int （*set_time）（struct device *, struct rtc_time *）; int （*read_alarm）（struct device *, struct rtc_wkalrm *）; int （*set_alarm）（struct device *, struct rtc_wkalrm *）; int （*proc）（struct device *, struct seq_file *）; int （*set_mmss）（struct device *, unsigned long secs）; int （*irq_set_state）（struct device *, int enabled）; int （*irq_set_freq）（struct device *, int freq）; int （*read_callback）（struct device *, int data）; }; struct rtc_device { struct device dev; struct module *owner;
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