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-rw-r--r--arch/powerpc/platforms/maple/time.c24
1 files changed, 2 insertions, 22 deletions
diff --git a/arch/powerpc/platforms/maple/time.c b/arch/powerpc/platforms/maple/time.c
index 5e6981d17379..b9a2b3d4bf33 100644
--- a/arch/powerpc/platforms/maple/time.c
+++ b/arch/powerpc/platforms/maple/time.c
@@ -60,34 +60,14 @@ static void maple_clock_write(unsigned long val, int addr)
60 60
61void maple_get_rtc_time(struct rtc_time *tm) 61void maple_get_rtc_time(struct rtc_time *tm)
62{ 62{
63 int uip, i; 63 do {
64
65 /* The Linux interpretation of the CMOS clock register contents:
66 * When the Update-In-Progress (UIP) flag goes from 1 to 0, the
67 * RTC registers show the second which has precisely just started.
68 * Let's hope other operating systems interpret the RTC the same way.
69 */
70
71 /* Since the UIP flag is set for about 2.2 ms and the clock
72 * is typically written with a precision of 1 jiffy, trying
73 * to obtain a precision better than a few milliseconds is
74 * an illusion. Only consistency is interesting, this also
75 * allows to use the routine for /dev/rtc without a potential
76 * 1 second kernel busy loop triggered by any reader of /dev/rtc.
77 */
78
79 for (i = 0; i<1000000; i++) {
80 uip = maple_clock_read(RTC_FREQ_SELECT);
81 tm->tm_sec = maple_clock_read(RTC_SECONDS); 64 tm->tm_sec = maple_clock_read(RTC_SECONDS);
82 tm->tm_min = maple_clock_read(RTC_MINUTES); 65 tm->tm_min = maple_clock_read(RTC_MINUTES);
83 tm->tm_hour = maple_clock_read(RTC_HOURS); 66 tm->tm_hour = maple_clock_read(RTC_HOURS);
84 tm->tm_mday = maple_clock_read(RTC_DAY_OF_MONTH); 67 tm->tm_mday = maple_clock_read(RTC_DAY_OF_MONTH);
85 tm->tm_mon = maple_clock_read(RTC_MONTH); 68 tm->tm_mon = maple_clock_read(RTC_MONTH);
86 tm->tm_year = maple_clock_read(RTC_YEAR); 69 tm->tm_year = maple_clock_read(RTC_YEAR);
87 uip |= maple_clock_read(RTC_FREQ_SELECT); 70 } while (tm->tm_sec != maple_clock_read(RTC_SECONDS));
88 if ((uip & RTC_UIP)==0)
89 break;
90 }
91 71
92 if (!(maple_clock_read(RTC_CONTROL) & RTC_DM_BINARY) 72 if (!(maple_clock_read(RTC_CONTROL) & RTC_DM_BINARY)
93 || RTC_ALWAYS_BCD) { 73 || RTC_ALWAYS_BCD) {