通过/sys/class/rtc/rtcX/date 获取rtc的时间
每个rtc的driver都会调用rtc_device_register 来想系统注册rtc的驱动,在rtc_device_register中会自动为每个rtc device建立一个sys的接口
rtc->dev.class = rtc_class;
rtc->dev.groups = rtc_get_dev_attribute_groups();
为rtc建立的sys的入口的源码在drivers/rtc/rtc-sysfs.c 中
static struct attribute_group rtc_attr_group = {
.is_visible = rtc_attr_is_visible,
.attrs = rtc_attrs,
};
static const struct attribute_group *rtc_attr_groups[] = {
&rtc_attr_group,
NULL
};
const struct attribute_group **rtc_get_dev_attribute_groups(void)
{
return rtc_attr_groups;
}
static struct attribute *rtc_attrs[] = {
&dev_attr_name.attr,
&dev_attr_date.attr,
NULL,
};
这里以date命令为例
static ssize_t
date_show(struct device *dev, struct device_attribute *attr, char *buf)
{
ssize_t retval;
struct rtc_time tm;
retval = rtc_read_time(to_rtc_device(dev), &tm);
if (retval == 0) {
retval = sprintf(buf, "%04d-%02d-%02d\n",
tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
}
return retval;
}
static DEVICE_ATTR_RO(date);
实际运行效果如下图:
rtc->dev.class = rtc_class;
rtc->dev.groups = rtc_get_dev_attribute_groups();
为rtc建立的sys的入口的源码在drivers/rtc/rtc-sysfs.c 中
static struct attribute_group rtc_attr_group = {
.is_visible = rtc_attr_is_visible,
.attrs = rtc_attrs,
};
static const struct attribute_group *rtc_attr_groups[] = {
&rtc_attr_group,
NULL
};
const struct attribute_group **rtc_get_dev_attribute_groups(void)
{
return rtc_attr_groups;
}
static struct attribute *rtc_attrs[] = {
&dev_attr_name.attr,
&dev_attr_date.attr,
NULL,
};
这里以date命令为例
static ssize_t
date_show(struct device *dev, struct device_attribute *attr, char *buf)
{
ssize_t retval;
struct rtc_time tm;
retval = rtc_read_time(to_rtc_device(dev), &tm);
if (retval == 0) {
retval = sprintf(buf, "%04d-%02d-%02d\n",
tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
}
return retval;
}
static DEVICE_ATTR_RO(date);
实际运行效果如下图: