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    Subject[PATCH 3.11 175/233] rtc: max8907: weekday encoding fixes
    Date
    3.11.10.4 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Stephen Warren <swarren@nvidia.com>

    commit 75ea799df4cb07e505c91b4abaa87bc28aad3e66 upstream.

    The current MAX8907 driver has two issues related to weekday value
    handling:

    1)

    The HW WEEKDAY register has range 0..6 rather than 1..7 as documented.
    Note that I validated the actual HW range by observing the HW register
    roll from 6->0 rather than 6->7->1 as would otherwise be expected.

    This matches Linux's tm_wday range of 0..6.

    When the CMOS RAM content is lost, the date returned from the device is
    2007-01-01 00:00:00, which is a Monday. The WEEKDAY register reads 1 in
    this case. This matches the numbering in Linux's tm_wday field.

    Hence we should write Linux's tm_wday value to the register without
    modifying it. Hence, remove the +1/-1 calculations for WEEKDAY/tm_wday.

    2)

    There's no need to make alarms match on the WEEKDAY register, since the
    other fields together uniquely define the alarm date/time. Ignoring the
    WEEKDAY value in the match isolates the driver from any incorrect value in
    the current time copy of the WEEKDAY register.

    Each change individually, or both together, solves an issue that I
    observed; "hwclock -r" would time out waiting for its alarm to fire if the
    CMOS RAM content had been lost, and hence the WEEKDAY register value
    mismatched what the driver expected it to be. "hwclock -w" would solve
    this by over-writing the HW default WEEKDAY register value with what the
    driver expected.

    Signed-off-by: Stephen Warren <swarren@nvidia.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
    ---
    drivers/rtc/rtc-max8907.c | 11 +++++------
    1 file changed, 5 insertions(+), 6 deletions(-)

    diff --git a/drivers/rtc/rtc-max8907.c b/drivers/rtc/rtc-max8907.c
    index 8e45b3c..3032178 100644
    --- a/drivers/rtc/rtc-max8907.c
    +++ b/drivers/rtc/rtc-max8907.c
    @@ -51,7 +51,7 @@ static irqreturn_t max8907_irq_handler(int irq, void *data)
    {
    struct max8907_rtc *rtc = data;

    - regmap_update_bits(rtc->regmap, MAX8907_REG_ALARM0_CNTL, 0x7f, 0);
    + regmap_write(rtc->regmap, MAX8907_REG_ALARM0_CNTL, 0);

    rtc_update_irq(rtc->rtc_dev, 1, RTC_IRQF | RTC_AF);

    @@ -64,7 +64,7 @@ static void regs_to_tm(u8 *regs, struct rtc_time *tm)
    bcd2bin(regs[RTC_YEAR1]) - 1900;
    tm->tm_mon = bcd2bin(regs[RTC_MONTH] & 0x1f) - 1;
    tm->tm_mday = bcd2bin(regs[RTC_DATE] & 0x3f);
    - tm->tm_wday = (regs[RTC_WEEKDAY] & 0x07) - 1;
    + tm->tm_wday = (regs[RTC_WEEKDAY] & 0x07);
    if (regs[RTC_HOUR] & HOUR_12) {
    tm->tm_hour = bcd2bin(regs[RTC_HOUR] & 0x01f);
    if (tm->tm_hour == 12)
    @@ -88,7 +88,7 @@ static void tm_to_regs(struct rtc_time *tm, u8 *regs)
    regs[RTC_YEAR1] = bin2bcd(low);
    regs[RTC_MONTH] = bin2bcd(tm->tm_mon + 1);
    regs[RTC_DATE] = bin2bcd(tm->tm_mday);
    - regs[RTC_WEEKDAY] = tm->tm_wday + 1;
    + regs[RTC_WEEKDAY] = tm->tm_wday;
    regs[RTC_HOUR] = bin2bcd(tm->tm_hour);
    regs[RTC_MIN] = bin2bcd(tm->tm_min);
    regs[RTC_SEC] = bin2bcd(tm->tm_sec);
    @@ -153,7 +153,7 @@ static int max8907_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
    tm_to_regs(&alrm->time, regs);

    /* Disable alarm while we update the target time */
    - ret = regmap_update_bits(rtc->regmap, MAX8907_REG_ALARM0_CNTL, 0x7f, 0);
    + ret = regmap_write(rtc->regmap, MAX8907_REG_ALARM0_CNTL, 0);
    if (ret < 0)
    return ret;

    @@ -163,8 +163,7 @@ static int max8907_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
    return ret;

    if (alrm->enabled)
    - ret = regmap_update_bits(rtc->regmap, MAX8907_REG_ALARM0_CNTL,
    - 0x7f, 0x7f);
    + ret = regmap_write(rtc->regmap, MAX8907_REG_ALARM0_CNTL, 0x77);

    return ret;
    }
    --
    1.8.3.2


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