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Commit ecb4a353 authored by Baruch Siach's avatar Baruch Siach Committed by Alexandre Belloni
Browse files

rtc: pcf8523: don't return invalid date when battery is low 



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: default avatarErik Čuk <erik.cuk@domel.com>
Signed-off-by: default avatarBaruch Siach <baruch@tkos.co.il>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
parent 2cb5e474

drivers/rtc/rtc-pcf8523.c

+24 −8
Original line number Diff line number Diff line
@@ -85,6 +85,18 @@ static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value) 
	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 device *dev, struct rtc_time *tm) 
	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 device *dev, unsigned int cmd, 
			     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;