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Subject[PATCH v2 1/1] rtc: ds1685: correct check of day of month
Date
The day of month is checked in ds1685_rtc_read_alarm
and ds1685_rtc_set_alarm.

Multiple errors exist in the day of month check.

Operator ! has a higher priority than &&.
(!(mday >= 1) && (mday <= 31)) is false for mday == 32.

When verifying the day of month the binary and the BCD mode
have to be considered.

v2:
consider ds1685_rtc_read_alarm
consider rtc->bcd_mode as indicated by Alexandre Belloni

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
---
drivers/rtc/rtc-ds1685.c | 34 +++++++++++++++++++++++++++++-----
1 file changed, 29 insertions(+), 5 deletions(-)

diff --git a/drivers/rtc/rtc-ds1685.c b/drivers/rtc/rtc-ds1685.c
index b3ce3c6..92e2f27 100644
--- a/drivers/rtc/rtc-ds1685.c
+++ b/drivers/rtc/rtc-ds1685.c
@@ -103,6 +103,26 @@ ds1685_rtc_bin2bcd(struct ds1685_priv *rtc, u8 val, u8 bin_mask, u8 bcd_mask)
}

/**
+ * s1685_rtc_check_mday - check validity of the day of month.
+ * @rtc: pointer to the ds1685 rtc structure.
+ * @mday: day of month.
+ *
+ * Returns -EDOM if the day of month is not within 1..31 range.
+ */
+static inline int
+ds1685_rtc_check_mday(struct ds1685_priv *rtc, u8 mday)
+{
+ if (rtc->bcd_mode) {
+ if (mday < 0x01 || mday > 0x31 || (mday & 0x0f) > 0x09)
+ return -EDOM;
+ } else {
+ if (mday < 1 || mday > 31)
+ return -EDOM;
+ }
+ return 0;
+}
+
+/**
* ds1685_rtc_switch_to_bank0 - switch the rtc to bank 0.
* @rtc: pointer to the ds1685 rtc structure.
*/
@@ -377,6 +397,7 @@ ds1685_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
struct platform_device *pdev = to_platform_device(dev);
struct ds1685_priv *rtc = platform_get_drvdata(pdev);
u8 seconds, minutes, hours, mday, ctrlb, ctrlc;
+ int ret;

/* Fetch the alarm info from the RTC alarm registers. */
ds1685_rtc_begin_data_access(rtc);
@@ -388,9 +409,10 @@ ds1685_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
ctrlc = rtc->read(rtc, RTC_CTRL_C);
ds1685_rtc_end_data_access(rtc);

- /* Check month date. */
- if (!(mday >= 1) && (mday <= 31))
- return -EDOM;
+ /* Check the month date for validity. */
+ ret = ds1685_rtc_check_mday(rtc, mday);
+ if (ret)
+ return ret;

/*
* Check the three alarm bytes.
@@ -445,6 +467,7 @@ ds1685_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
struct platform_device *pdev = to_platform_device(dev);
struct ds1685_priv *rtc = platform_get_drvdata(pdev);
u8 ctrlb, seconds, minutes, hours, mday;
+ int ret;

/* Fetch the alarm info and convert to BCD. */
seconds = ds1685_rtc_bin2bcd(rtc, alrm->time.tm_sec,
@@ -461,8 +484,9 @@ ds1685_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
RTC_MDAY_BCD_MASK);

/* Check the month date for validity. */
- if (!(mday >= 1) && (mday <= 31))
- return -EDOM;
+ ret = ds1685_rtc_check_mday(rtc, mday);
+ if (ret)
+ return ret;

/*
* Check the three alarm bytes.
--
2.1.4
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