[RTC] Read function in RTC Driver

1420 단어 function
read:  the standard read function call.
ssize_t read(int file_handler, viod *buf, size_t nbytes);



In the RTC driver, the read function is used to wait for the RTC device interrupt.
When call the read function, the application is locked until a interrupt is generated.

USAGE:
------
int fd;
int ret;
struct rtc_time rtc_tm;
unsigned long data;

   ===> why "unsigned long" type.





fd = open("/dev/rtc", O_RDONLY, 0);
ret = ioctl(fd, RTC_ALM_SET, &rtc_tm);
// call the read function to wait the Alarm interrupt
ret = read(fd, &data, sizeof(unsigned long));
...
close(fd);

Reference:


http://www.uclinux.org/pub/uClinux/ports/blackfin/docs/Device%20Driver%20Integration%20Notes%20and%20Tests/RTC_device_driver.txt

http://ww2.cs.fsu.edu/~rosentha/linux/2.6.26.5/docs/rtc.txt


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