From: Baruch Siach baruch@tkos.co.il
commit ecb4a353d3afd45b9bb30c85d03ee113a0589079 upstream.
The RTC_VL_READ ioctl reports the low battery condition. Still, pcf8523_rtc_read_time() happily returns invalid dates in this case. Check the battery health on pcf8523_rtc_read_time() to avoid that.
Reported-by: Erik Čuk erik.cuk@domel.com Signed-off-by: Baruch Siach baruch@tkos.co.il Signed-off-by: Alexandre Belloni alexandre.belloni@bootlin.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/rtc/rtc-pcf8523.c | 32 ++++++++++++++++++++++++-------- 1 file changed, 24 insertions(+), 8 deletions(-)
--- a/drivers/rtc/rtc-pcf8523.c +++ b/drivers/rtc/rtc-pcf8523.c @@ -85,6 +85,18 @@ static int pcf8523_write(struct i2c_clie return 0; }
+static int pcf8523_voltage_low(struct i2c_client *client) +{ + u8 value; + int err; + + err = pcf8523_read(client, REG_CONTROL3, &value); + if (err < 0) + return err; + + return !!(value & REG_CONTROL3_BLF); +} + static int pcf8523_select_capacitance(struct i2c_client *client, bool high) { u8 value; @@ -167,6 +179,14 @@ static int pcf8523_rtc_read_time(struct struct i2c_msg msgs[2]; int err;
+ err = pcf8523_voltage_low(client); + if (err < 0) { + return err; + } else if (err > 0) { + dev_err(dev, "low voltage detected, time is unreliable\n"); + return -EINVAL; + } + msgs[0].addr = client->addr; msgs[0].flags = 0; msgs[0].len = 1; @@ -251,17 +271,13 @@ static int pcf8523_rtc_ioctl(struct devi unsigned long arg) { struct i2c_client *client = to_i2c_client(dev); - u8 value; - int ret = 0, err; + int ret;
switch (cmd) { case RTC_VL_READ: - err = pcf8523_read(client, REG_CONTROL3, &value); - if (err < 0) - return err; - - if (value & REG_CONTROL3_BLF) - ret = 1; + ret = pcf8523_voltage_low(client); + if (ret < 0) + return ret;
if (copy_to_user((void __user *)arg, &ret, sizeof(int))) return -EFAULT;