drivers/rtc/bfin_rtc.c

   1 /*
   2  * Copyright (c) 2004-2008 Analog Devices Inc.
   3  *
   4  * (C) Copyright 2001
   5  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   6  *
   7  * Licensed under the GPL-2 or later.
   8  */
   9
  10 #include <common.h>
  11 #include <command.h>
  12 #include <rtc.h>
  13
  14 #if defined(CONFIG_CMD_DATE)
  15
  16 #include <asm/blackfin.h>
  17 #include <asm/mach-common/bits/rtc.h>
  18
  19 #define pr_stamp() debug("%s:%s:%i: here i am\n", __FILE__, __func__, __LINE__)
  20
  21 #define MIN_TO_SECS(x)    (60 * (x))
  22 #define HRS_TO_SECS(x)    (60 * MIN_TO_SECS(x))
  23 #define DAYS_TO_SECS(x)   (24 * HRS_TO_SECS(x))
  24
  25 #define NUM_SECS_IN_MIN   MIN_TO_SECS(1)
  26 #define NUM_SECS_IN_HR    HRS_TO_SECS(1)
  27 #define NUM_SECS_IN_DAY   DAYS_TO_SECS(1)
  28
  29 /* Enable the RTC prescaler enable register */
  30 void rtc_init(void)
  31 {
  32         if (!(bfin_read_RTC_PREN() & 0x1))
  33                 bfin_write_RTC_PREN(0x1);
  34 }
  35
  36 /* Our on-chip RTC has no notion of "reset" */
  37 void rtc_reset(void)
  38 {
  39         rtc_init();
  40 }
  41
  42 /* Wait for pending writes to complete */
  43 static void wait_for_complete(void)
  44 {
  45         pr_stamp();
  46         while (!(bfin_read_RTC_ISTAT() & WRITE_COMPLETE))
  47                 if (!(bfin_read_RTC_ISTAT() & WRITE_PENDING))
  48                         break;
  49         bfin_write_RTC_ISTAT(WRITE_COMPLETE);
  50 }
  51
  52 /* Set the time. Get the time_in_secs which is the number of seconds since Jan 1970 and set the RTC registers
  53  * based on this value.
  54  */
  55 int rtc_set(struct rtc_time *tmp)
  56 {
  57         unsigned long remain, days, hrs, mins, secs;
  58
  59         pr_stamp();
  60
  61         if (tmp == NULL) {
  62                 puts("Error setting the date/time\n");
  63                 return -1;
  64         }
  65
  66         rtc_init();
  67         wait_for_complete();
  68
  69         /* Calculate number of seconds this incoming time represents */
  70         remain = rtc_mktime(tmp);
  71
  72         /* Figure out how many days since epoch */
  73         days = remain / NUM_SECS_IN_DAY;
  74
  75         /* From the remaining secs, compute the hrs(0-23), mins(0-59) and secs(0-59) */
  76         remain = remain % NUM_SECS_IN_DAY;
  77         hrs = remain / NUM_SECS_IN_HR;
  78         remain = remain % NUM_SECS_IN_HR;
  79         mins = remain / NUM_SECS_IN_MIN;
  80         secs = remain % NUM_SECS_IN_MIN;
  81
  82         /* Encode these time values into our RTC_STAT register */
  83         bfin_write_RTC_STAT(SET_ALARM(days, hrs, mins, secs));
  84
  85         return 0;
  86 }
  87
  88 /* Read the time from the RTC_STAT. time_in_seconds is seconds since Jan 1970 */
  89 int rtc_get(struct rtc_time *tmp)
  90 {
  91         uint32_t cur_rtc_stat;
  92         int time_in_sec;
  93         int tm_sec, tm_min, tm_hr, tm_day;
  94
  95         pr_stamp();
  96
  97         if (tmp == NULL) {
  98                 puts("Error getting the date/time\n");
  99                 return -1;
 100         }
 101
 102         rtc_init();
 103         wait_for_complete();
 104
 105         /* Read the RTC_STAT register */
 106         cur_rtc_stat = bfin_read_RTC_STAT();
 107
 108         /* Convert our encoded format into actual time values */
 109         tm_sec = (cur_rtc_stat & RTC_SEC) >> RTC_SEC_P;
 110         tm_min = (cur_rtc_stat & RTC_MIN) >> RTC_MIN_P;
 111         tm_hr  = (cur_rtc_stat & RTC_HR ) >> RTC_HR_P;
 112         tm_day = (cur_rtc_stat & RTC_DAY) >> RTC_DAY_P;
 113
 114         /* Calculate the total number of seconds since epoch */
 115         time_in_sec = (tm_sec) + MIN_TO_SECS(tm_min) + HRS_TO_SECS(tm_hr) + DAYS_TO_SECS(tm_day);
 116         rtc_to_tm(time_in_sec, tmp);
 117
 118         return 0;
 119 }
 120
 121 #endif