UM0851 datasheet(41/245 Pages) STMICROELECTRONICS

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UM0851

Platform section

Doc ID 16604 Rev 2

41/245

&spear_rtc_ops, THIS_MODULE);

The following system calls are supported by Linux RTC framework.

Opening the RTC device

The open function is used to establish the connection between the RTC device and a file

descriptor.

int fd;

fd = open("/dev/rtc", O_RDONLY, 0);

IOCTL operations

The ioctl command is used to configure the RTC device.

int fd;

struct rtc_time rtc_tm;

int ret;

fd = open("/dev/rtc", O_RDONLY, 0);

...

/* the ioctl command RTC_RD_TIME is used

* to read the current timer.

ret = ioctl(rtc_fd, RTC_RD_TIME, &rtc_tm);

...

close(fd);

Read from RTC device

This is the standard read function call. In the RTC driver, the read function is used to wait for

the RTC device interrupt. When the read function is called, the application is locked until an

interrupt is generated.

int fd;

int ret;

struct rtc_time rtc_tm;

unsigned long data;

Table 13.

RTC ioctl requests

Request

Description

RTC_AIE_OFF

This ioctl does not need an argument, and it can be used to disable the

RTC alarm interrupt.

RTC_AIE_ON

This ioctl does not need an argument, and it can be used to enable the

RTC alarm interrupt.

RTC_ALM_READ

This ioctl needs one argument (struct rtc_time *), and it can be used to

get the current RTC alarm parameter.

RTC_ALM_SET

This ioctl needs one argument (struct rtc_time *), and it can be used to

set the RTC alarm.

RTC_RD_TIME

This ioctl needs one argument (struct rtc_time *), and it can be used to

get the current RTC time.

RTC_SET_TIME

This ioctl needs one argument (struct rtc_time *), and it can be used to

set the current RTC time.

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