The patch titled
Subject: drivers/rtc/rtc-isl12057.c: add support for century bit
has been added to the -mm tree. Its filename is
rtc-rtc-isl12057-add-support-for-century-bit.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/rtc-rtc-isl12057-add-support-for-century-bit.patch
echo and later at
echo http://ozlabs.org/~akpm/mmotm/broken-out/rtc-rtc-isl12057-add-support-for-century-bit.patch
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From: Arnaud Ebalard <arno@xxxxxxxxxxxx>
Subject: drivers/rtc/rtc-isl12057.c: add support for century bit
The month register of ISL12057 RTC chip includes a century bit which
reports overflow of year register from 99 to 0. This bit can also be
written, which allows using it to extend the time interval the chip can
support from 99 to 199 years.
This patch adds support for century overflow bit in tm to regs and regs to
tm helpers in ISL12057 driver.
This was tested by putting a device 100 years in the future (using a
specific kernel due to the inability of userland tools such as date or
hwclock to pass year 2038), rebooting on a kernel w/ this patch applied
and verifying the device was still 100 years in the future.
Signed-off-by: Arnaud Ebalard <arno@xxxxxxxxxxxx>
Suggested-by: Uwe Kleine-König <uwe@xxxxxxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
Cc: Peter Huewe <peter.huewe@xxxxxxxxxxxx>
Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
Cc: Thierry Reding <treding@xxxxxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Grant Likely <grant.likely@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/rtc/rtc-isl12057.c | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
diff -puN drivers/rtc/rtc-isl12057.c~rtc-rtc-isl12057-add-support-for-century-bit drivers/rtc/rtc-isl12057.c
--- a/drivers/rtc/rtc-isl12057.c~rtc-rtc-isl12057-add-support-for-century-bit
+++ a/drivers/rtc/rtc-isl12057.c
@@ -41,6 +41,7 @@
#define ISL12057_REG_RTC_DW 0x03 /* Day of the Week */
#define ISL12057_REG_RTC_DT 0x04 /* Date */
#define ISL12057_REG_RTC_MO 0x05 /* Month */
+#define ISL12057_REG_RTC_MO_CEN BIT(7) /* Century bit */
#define ISL12057_REG_RTC_YR 0x06 /* Year */
#define ISL12057_RTC_SEC_LEN 7
@@ -99,24 +100,35 @@ static void isl12057_rtc_regs_to_tm(stru
tm->tm_wday = bcd2bin(regs[ISL12057_REG_RTC_DW]) - 1; /* starts at 1 */
tm->tm_mon = bcd2bin(regs[ISL12057_REG_RTC_MO] & 0x1f) - 1; /* ditto */
tm->tm_year = bcd2bin(regs[ISL12057_REG_RTC_YR]) + 100;
+
+ /* Check if years register has overflown from 99 to 00 */
+ if (regs[ISL12057_REG_RTC_MO] & ISL12057_REG_RTC_MO_CEN)
+ tm->tm_year += 100;
}
static int isl12057_rtc_tm_to_regs(u8 *regs, struct rtc_time *tm)
{
+ u8 century_bit;
+
/*
* The clock has an 8 bit wide bcd-coded register for the year.
+ * It also has a century bit encoded in MO flag which provides
+ * information about overflow of year register from 99 to 00.
* tm_year is an offset from 1900 and we are interested in the
- * 2000-2099 range, so any value less than 100 is invalid.
+ * 2000-2199 range, so any value less than 100 or larger than
+ * 299 is invalid.
*/
- if (tm->tm_year < 100)
+ if (tm->tm_year < 100 || tm->tm_year > 299)
return -EINVAL;
+ century_bit = (tm->tm_year > 199) ? ISL12057_REG_RTC_MO_CEN : 0;
+
regs[ISL12057_REG_RTC_SC] = bin2bcd(tm->tm_sec);
regs[ISL12057_REG_RTC_MN] = bin2bcd(tm->tm_min);
regs[ISL12057_REG_RTC_HR] = bin2bcd(tm->tm_hour); /* 24-hour format */
regs[ISL12057_REG_RTC_DT] = bin2bcd(tm->tm_mday);
- regs[ISL12057_REG_RTC_MO] = bin2bcd(tm->tm_mon + 1);
- regs[ISL12057_REG_RTC_YR] = bin2bcd(tm->tm_year - 100);
+ regs[ISL12057_REG_RTC_MO] = bin2bcd(tm->tm_mon + 1) | century_bit;
+ regs[ISL12057_REG_RTC_YR] = bin2bcd(tm->tm_year % 100);
regs[ISL12057_REG_RTC_DW] = bin2bcd(tm->tm_wday + 1);
return 0;
_
Patches currently in -mm which might be from arno@xxxxxxxxxxxx are
rtc-rtc-isl12057-fix-masking-of-register-values.patch
rtc-rtc-isl12057-add-support-for-century-bit.patch
rtc-rtc-isl12057-add-proper-handling-of-oscillator-failure-bit.patch
rtc-rtc-isl12057-fix-isil-vs-isl-naming-for-intersil.patch
rtc-rtc-isl12057-report-error-code-upon-failure-in-dev_err-calls.patch
rtc-rtc-isl12057-add-alarm-support-to-intersil-isl12057-rtc-driver.patch
linux-next.patch
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