uboot一般不会要求开启rtc，只是还是支持rtc以备特殊需求的。
底层驱动移植前面两篇已经介绍。这里介绍顶层的调用过程。顶层在uboot/common/cmd_date.c
/*
* (C) Copyright 2001
* Wolfgang Denk, DENX Software Engineering, [email protected]
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
/*
* RTC, Date & Time support: get and set date & time
*/
include
include
include
include
ifdef CONFIG_RELOC_FIXUP_WORKS
define RELOC(a) a
else
define RELOC(a) ((typeof(a))((unsigned long)(a) + gd->reloc_off))
endif
int mk_date (char , struct rtc_time );
int do_date (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
{
struct rtc_time tm;
int rcode = 0;
int old_bus;
/* switch to correct I2C bus */
old_bus = I2C_GET_BUS();
I2C_SET_BUS(CONFIG_SYS_RTC_BUS_NUM);
switch (argc) {
case 2: /* set date & time */
if (strcmp(argv[1],"reset") == 0) {
puts ("Reset RTC...\n");
rtc_reset ();
} else {
/* initialize tm with current time */
rcode = rtc_get (&tm);
if(!rcode) {
/* insert new date & time */
if (mk_date (argv[1], &tm) != 0) {
puts ("## Bad date format\n");
break;
}
/* and write to RTC */
rcode = rtc_set (&tm);
if(rcode)
puts("## Set date failed\n");
} else {
puts("## Get date failed\n");
}
}
/* FALL TROUGH */
case 1: /* get date & time */
rcode = rtc_get (&tm);
if (rcode) {
puts("## Get date failed\n");
break;
}
printf ("Date: %4d-%02d-%02d (%sday) Time: %2d:%02d:%02d\n",
tm.tm_year, tm.tm_mon, tm.tm_mday,
(tm.tm_wday<0 || tm.tm_wday>6) ?
"unknown " : RELOC(weekdays[tm.tm_wday]),
tm.tm_hour, tm.tm_min, tm.tm_sec);
break;
default:
cmd_usage(cmdtp);
rcode = 1;
}
/* switch back to original I2C bus */
I2C_SET_BUS(old_bus);
return rcode;
}
/*
* simple conversion of two-digit string with error checking
*/
static int cnvrt2 (char *str, int *valp)
{
int val;
if ((*str < ‘0‘) || (*str > ‘9‘))
return (-1);
val = *str - ‘0‘;
++str;
if ((*str < ‘0‘) || (*str > ‘9‘))
return (-1);
*valp = 10 * val + (*str - ‘0‘);
return (0);
}
/*
* Convert date string: MMDDhhmm[[CC]YY][.ss]
*
* Some basic checking for valid values is done, but this will not catch
* all possible error conditions.
*/
int mk_date (char *datestr, struct rtc_time *tmp)
{
int len, val;
char *ptr;
ptr = strchr (datestr,‘.‘);
len = strlen (datestr);
/* Set seconds */
if (ptr) {
int sec;
*ptr++ = ‘\0‘;
if ((len - (ptr - datestr)) != 2)
return (-1);
len = strlen (datestr);
if (cnvrt2 (ptr, &sec))
return (-1);
tmp->tm_sec = sec;
} else {
tmp->tm_sec = 0;
}
if (len == 12) { /* MMDDhhmmCCYY */
int year, century;
if (cnvrt2 (datestr+ 8, ¢ury) ||
cnvrt2 (datestr+10, &year) ) {
return (-1);
}
tmp->tm_year = 100 * century + year;
} else if (len == 10) { /* MMDDhhmmYY */
int year, century;
century = tmp->tm_year / 100;
if (cnvrt2 (datestr+ 8, &year))
return (-1);
tmp->tm_year = 100 * century + year;
}
switch (len) {
case 8: /* MMDDhhmm */
/* fall thru */
case 10: /* MMDDhhmmYY */
/* fall thru */
case 12: /* MMDDhhmmCCYY */
if (cnvrt2 (datestr+0, &val) ||
val > 12) {
break;
}
tmp->tm_mon = val;
if (cnvrt2 (datestr+2, &val) ||
val > ((tmp->tm_mon==2) ? 29 : 31)) {
break;
}
tmp->tm_mday = val;
if (cnvrt2 (datestr+4, &val) ||
val > 23) {
break;
}
tmp->tm_hour = val;
if (cnvrt2 (datestr+6, &val) ||
val > 59) {
break;
}
tmp->tm_min = val;
/* calculate day of week */
GregorianDay (tmp);
return (0);
default:
break;
}
return (-1);
}
/*****************************************/
U_BOOT_CMD(
date, 2, 1, do_date,
“get/set/reset date & time”,
“[MMDDhhmm[[CC]YY][.ss]]\ndate reset\n”
” - without arguments: print date & time\n”
” - with numeric argument: set the system date & time\n”
” - with ‘reset’ argument: reset the RTC”
);
这里反向分析：
第一步是注冊 date命令
U_BOOT_CMD(
date, 2, 1, do_date,
“get/set/reset date & time”,
“[MMDDhhmm[[CC]YY][.ss]]\ndate reset\n”
” - without arguments: print date & time\n”
” - with numeric argument: set the system date & time\n”
” - with ‘reset’ argument: reset the RTC”
);
这个命令就是rtc的控制命令了 调用的函数是 do_date
int do_date (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
能够看到这命令是调用了rtc里面注冊的rtc_reset、rtc_get、rtc_set
分为case1 ：获取当年的时间
case2 设置时间；
时间转换函数mk_date 能够将我们输入的字符串转化成为时间的年月日 供rtc_set 配置下去去