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List: linux-rtc
Subject: [PATCH 5/5] rtc: rv8803: invalidate date/time if alarm time is invalid
From: Sascha Hauer <s.hauer () pengutronix ! de>
Date: 2022-04-26 7:10:56
Message-ID: 20220426071056.1187235-6-s.hauer () pengutronix ! de
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From: Ahmad Fatoum <a.fatoum@pengutronix.de>
RTC core never calls rv8803_set_alarm with an invalid alarm time,
so if an invalid alarm time > 0 is set, external factors must have
corrupted the RTC's alarm time and possibly other registers.
Play it safe by marking the date/time invalid, so all registers are
reinitialized on a ->set_time.
This may cause existing setups to lose time if they so far set only
date/time, but ignored that the alarm registers had an invalid date
value, e.g.:
rtc rtc0: invalid alarm value: 2020-3-27 7:82:0
These systems will have their ->get_time return -EINVAL till
->set_time initializes the alarm value (and sets a new time).
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
drivers/rtc/rtc-rv8803.c | 46 +++++++++++++++++++++++++++++++---------
1 file changed, 36 insertions(+), 10 deletions(-)
diff --git a/drivers/rtc/rtc-rv8803.c b/drivers/rtc/rtc-rv8803.c
index fe1247e771b98..036c449cf1c20 100644
--- a/drivers/rtc/rtc-rv8803.c
+++ b/drivers/rtc/rtc-rv8803.c
@@ -70,6 +70,7 @@ struct rv8803_data {
struct mutex flags_lock;
u8 ctrl;
u8 backup;
+ u8 alarm_invalid:1;
enum rv8803_type type;
};
@@ -165,13 +166,13 @@ static int rv8803_regs_init(struct rv8803_data *rv8803)
static int rv8803_regs_configure(struct rv8803_data *rv8803);
-static int rv8803_regs_reset(struct rv8803_data *rv8803)
+static int rv8803_regs_reset(struct rv8803_data *rv8803, bool full)
{
/*
* The RV-8803 resets all registers to POR defaults after voltage-loss,
* the Epson RTCs don't, so we manually reset the remainder here.
*/
- if (rv8803->type == rx_8803 || rv8803->type == rx_8900) {
+ if (full || rv8803->type == rx_8803 || rv8803->type == rx_8900) {
int ret = rv8803_regs_init(rv8803);
if (ret)
return ret;
@@ -238,6 +239,11 @@ static int rv8803_get_time(struct device *dev, struct rtc_time *tm)
u8 *date = date1;
int ret, flags;
+ if (rv8803->alarm_invalid) {
+ dev_warn(dev, "Corruption detected, data may be invalid.\n");
+ return -EINVAL;
+ }
+
flags = rv8803_read_reg(rv8803->client, RV8803_FLAG);
if (flags < 0)
return flags;
@@ -313,10 +319,16 @@ static int rv8803_set_time(struct device *dev, struct rtc_time *tm)
return flags;
}
- if (flags & RV8803_FLAG_V2F) {
- ret = rv8803_regs_reset(rv8803);
+ if ((flags & RV8803_FLAG_V2F) || rv8803->alarm_invalid) {
+ /*
+ * If we sense corruption in the alarm registers, but see no
+ * voltage loss flag, we can't rely on other registers having
+ * sensible values. Reset them fully.
+ */
+ ret = rv8803_regs_reset(rv8803, rv8803->alarm_invalid);
if (ret)
return ret;
+ rv8803->alarm_invalid = false;
}
ret = rv8803_write_reg(rv8803->client, RV8803_FLAG,
@@ -342,13 +354,27 @@ static int rv8803_get_alarm(struct device *dev, struct rtc_wkalrm *alrm)
if (flags < 0)
return flags;
- alrm->time.tm_sec = 0;
- alrm->time.tm_min = bcd2bin(alarmvals[0] & 0x7f);
- alrm->time.tm_hour = bcd2bin(alarmvals[1] & 0x3f);
- alrm->time.tm_mday = bcd2bin(alarmvals[2] & 0x3f);
+ alarmvals[0] &= 0x7f;
+ alarmvals[1] &= 0x3f;
+ alarmvals[2] &= 0x3f;
+
+ if (bcd_is_valid(alarmvals[0]) && bcd_is_valid(alarmvals[1]) &&
+ bcd_is_valid(alarmvals[2])) {
+ alrm->time.tm_sec = 0;
+ alrm->time.tm_min = bcd2bin(alarmvals[0]);
+ alrm->time.tm_hour = bcd2bin(alarmvals[1]);
+ alrm->time.tm_mday = bcd2bin(alarmvals[2]);
- alrm->enabled = !!(rv8803->ctrl & RV8803_CTRL_AIE);
- alrm->pending = (flags & RV8803_FLAG_AF) && alrm->enabled;
+ alrm->enabled = !!(rv8803->ctrl & RV8803_CTRL_AIE);
+ alrm->pending = (flags & RV8803_FLAG_AF) && alrm->enabled;
+ }
+
+ if ((unsigned)alrm->time.tm_mday > 31 ||
+ (unsigned)alrm->time.tm_hour >= 24 ||
+ (unsigned)alrm->time.tm_min >= 60) {
+ rv8803->alarm_invalid = true;
+ return -EINVAL;
+ }
return 0;
}
--
2.30.2
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