[经验]

【MYD-YA157C开发板试用连载】+ 字符设备驱动之RTC

casy

2020-6-12 09:07:57

2560 STM32MP157

STM32mp1内部已经集成了RTC模块，所以我们操作起来就非常方便了。在嵌入式系统中，RTC还是使用的非常广泛的。

STM32MP1系列芯片已经内置RTC功能，可以直接配置使用，需要硬件连接RTC的备份电池。Linux kernel代码中启用RTC功能就可以使用了。

1.连接到Cortex-A7 GIC的安全中断，未在OpenSTLinux发行版中使用。

这里有两个步骤非常关键：

2. 设备与驱动成功匹配；

等待Linux启动完成后，我们可以在uart console中查看TRC是否正常工作：

root@pangu:~# dmesg| grep rtc
[ 1.859046] stm32_rtc 5c004000.rtc: rtc core: registered 5c004000.rtc as rtc0
[ 1.865008] stm32_rtc 5c004000.rtc: Date/time must be initialized
[ 1.870915] stm32_rtc 5c004000.rtc: registered rev:1.2
[ 2.327185] stm32_rtc 5c004000.rtc: setting system clock to 2000-01-01 05:19:06 UTC (946703946)
root@pangu:~# ls -la /dev/rtc*
lrwxrwxrwx 1 root root 4 Jul 16 06:58 /dev/rtc -> rtc0
crw------- 1 root root 253, 0 Jul 16 06:58 /dev/rtc0

复制代码

此时，我们就可以编写应用程序。
应用程先贴一个demo上来，主要功能就是设置和读取内核态的RTC硬件时间。

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
static const char default_rtc[] = "/dev/rtc0";
static char *program_name;
/**
* @brief: print help message
*/
static void help(void)
{
fprintf(stderr,
"tUsage: %s [OPTION]...n"
"t-h,--help helpn"
"t-s,--set set date/time given with you.ntinput format:./rtc_test [hour] [minute] [second] [year] [month] [day]n"
"t-r,--show read hardware clock and print resultn"
"n", program_name);
}
/**
* @brief: read RTC date and time
* @Param: fd: the file descriptor of rtc device
*/
void rtc_read_time(int fd)
{
int retval;
struct rtc_time rtc_tm;
/*read the RTC time/date*/
retval = ioctl(fd, RTC_RD_TIME, &rtc_tm);
if (retval == -1) {
perror("RTC_RD_TIME ioctl");
exit(errno);
}
fprintf(stderr, "ntCurrent RTC date/time is %d-%d-%d, %02d:%02d:%02d.nn",
rtc_tm.tm_mday, rtc_tm.tm_mon + 1, rtc_tm.tm_year + 1900,
rtc_tm.tm_hour, rtc_tm.tm_min, rtc_tm.tm_sec);
}
/**
* @brief: set rtc date and time
* @Param: fd: the file descriptor of rtc device
* @Param: hour: the hour to set
* @Param: minute: the minute to set
* @Param: second: the hour to set
* @Param: year: the year to set
* @Param: month: the month to set
* @Param: day: the day to set
*/
void rtc_set_time(int fd, int hour, int minute, int second, int year, int month, int day)
{
int retval;
struct rtc_time rtc_tm;
rtc_tm.tm_mday = day;
rtc_tm.tm_mon = month - 1;
rtc_tm.tm_year = year - 1900;
rtc_tm.tm_hour = hour;
rtc_tm.tm_min = minute;
rtc_tm.tm_wday = rtc_tm.tm_yday = rtc_tm.tm_isdst = 0;
rtc_tm.tm_sec = second;
/*set the RTC time/date*/
retval = ioctl(fd, RTC_SET_TIME, &rtc_tm);
if (retval == -1) {
perror("RTC_SET_TIME ioctl");
exit(errno);
}
fprintf(stderr, "nttdate/time is updated to: %d-%d-%d, %02d:%02d:%02d.nn",
rtc_tm.tm_mday, rtc_tm.tm_mon + 1, rtc_tm.tm_year + 1900,
rtc_tm.tm_hour, rtc_tm.tm_min, rtc_tm.tm_sec);
}
/**
* @brief: main function
* @Param: argc: number of parameters
* @Param: argv: parameters list
*/
int main(int argc, char *argv[])
{
int fd, retval, c;
int set_flag = 0, read_flag = 0;
struct rtc_time rtc_tm;
const char *rtc = default_rtc;
struct option long_option[] =
{
{"help", 0, NULL, 'h'},
{"set", 1, NULL, 's'},
{"show", 0, NULL, 'r'},
{NULL, 0, NULL, 0},
};
program_name = argv[0];
while (1) {
if ((c = getopt_long(argc, argv, "hs:r", long_option, NULL)) < 0)
break;
switch (c) {
case 'h':
help();
break;
case 's':
if (argc < 8) {
fprintf(stderr, "ntttime format error!nn");
exit(errno);
}
set_flag = 1;
break;
case 'r':
read_flag = 1;
break;
case '?':
help();
break;
default:
abort ();
}
}
/* open rtc device */
fd = open(rtc, O_RDWR);
if (fd == -1) {
perror(rtc);
exit(errno);
}
if (argc == 1) {
rtc_read_time(fd);
}
if (set_flag)
rtc_set_time(fd, atoi(argv[2]), atoi(argv[3]), atoi(argv[4]), atoi(argv[5]), atoi(argv[6]), atoi(argv[7]));
if (read_flag)
rtc_read_time(fd);
close(fd);
return 0;
}