[PATCH] rtc: rs5c372: Fix read the time from RTC is illegal When reading time from an uninitialized RTC chip, The value may be illegal

qxj511mail
2021-05-20T03:32:15Z

From: qiuxiaojin <qiuxiaojin@cvte.com>

Signed-off-by: qiuxiaojin <qiuxiaojin@cvte.com>
---
drivers/rtc/rtc-rs5c372.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/drivers/rtc/rtc-rs5c372.c b/drivers/rtc/rtc-rs5c372.c
index 3bd6eaa0dcf6..ce61e15d5f3a 100644
--- a/drivers/rtc/rtc-rs5c372.c
+++ b/drivers/rtc/rtc-rs5c372.c
@@ -212,6 +212,7 @@ static int rs5c372_rtc_read_time(struct device *dev, struct rtc_time *tm)
struct rs5c372 *rs5c = i2c_get_clientdata(client);
int status = rs5c_get_regs(rs5c);
unsigned char ctrl2 = rs5c->regs[RS5C_REG_CTRL2];
+ int flags_utime = 0;

if (status < 0)
return status;
@@ -239,12 +240,27 @@ static int rs5c372_rtc_read_time(struct device *dev, struct rtc_time *tm)
tm->tm_wday = bcd2bin(rs5c->regs[RS5C372_REG_WDAY] & 0x07);
tm->tm_mday = bcd2bin(rs5c->regs[RS5C372_REG_DAY] & 0x3f);

+ if (tm->tm_mday < 1) {
+ // The value read from the register may be zero, which is an illegal value
+ flags_utime = flags_utime + 1;
+ tm->tm_mday = 1;
+ }
+
/* tm->tm_mon is zero-based */
tm->tm_mon = bcd2bin(rs5c->regs[RS5C372_REG_MONTH] & 0x1f) - 1;

+ if (tm->tm_mon < 0) {
+ flags_utime = flags_utime + 1;
+ tm->tm_mday = 0;
+ }
+
/* year is 1900 + tm->tm_year */
tm->tm_year = bcd2bin(rs5c->regs[RS5C372_REG_YEAR]) + 100;

+ if (flags_utime > 0) {
+ rs5c372_rtc_set_time(dev, tm);
+ }
+
dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
"mday=%d, mon=%d, year=%d, wday=%d\n",
__func__,
--
2.29.0