1 From ecb4a353d3afd45b9bb30c85d03ee113a0589079 Mon Sep 17 00:00:00 2001
2 From: Baruch Siach <baruch@tkos.co.il>
3 Date: Wed, 5 Dec 2018 17:00:09 +0200
4 Subject: rtc: pcf8523: don't return invalid date when battery is low
6 Content-Type: text/plain; charset=UTF-8
7 Content-Transfer-Encoding: 8bit
9 From: Baruch Siach <baruch@tkos.co.il>
11 commit ecb4a353d3afd45b9bb30c85d03ee113a0589079 upstream.
13 The RTC_VL_READ ioctl reports the low battery condition. Still,
14 pcf8523_rtc_read_time() happily returns invalid dates in this case.
15 Check the battery health on pcf8523_rtc_read_time() to avoid that.
17 Reported-by: Erik Čuk <erik.cuk@domel.com>
18 Signed-off-by: Baruch Siach <baruch@tkos.co.il>
19 Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
20 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
23 drivers/rtc/rtc-pcf8523.c | 32 ++++++++++++++++++++++++--------
24 1 file changed, 24 insertions(+), 8 deletions(-)
26 --- a/drivers/rtc/rtc-pcf8523.c
27 +++ b/drivers/rtc/rtc-pcf8523.c
28 @@ -82,6 +82,18 @@ static int pcf8523_write(struct i2c_clie
32 +static int pcf8523_voltage_low(struct i2c_client *client)
37 + err = pcf8523_read(client, REG_CONTROL3, &value);
41 + return !!(value & REG_CONTROL3_BLF);
44 static int pcf8523_select_capacitance(struct i2c_client *client, bool high)
47 @@ -164,6 +176,14 @@ static int pcf8523_rtc_read_time(struct
48 struct i2c_msg msgs[2];
51 + err = pcf8523_voltage_low(client);
54 + } else if (err > 0) {
55 + dev_err(dev, "low voltage detected, time is unreliable\n");
59 msgs[0].addr = client->addr;
62 @@ -248,17 +268,13 @@ static int pcf8523_rtc_ioctl(struct devi
65 struct i2c_client *client = to_i2c_client(dev);
72 - err = pcf8523_read(client, REG_CONTROL3, &value);
76 - if (value & REG_CONTROL3_BLF)
78 + ret = pcf8523_voltage_low(client);
82 if (copy_to_user((void __user *)arg, &ret, sizeof(int)))