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

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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>
This commit is contained in:
Baruch Siach
2018-12-05 17:00:09 +02:00
committed by Alexandre Belloni
parent 2cb5e4743a
commit ecb4a353d3
1 changed files with 24 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
drivers/rtc/rtc-pcf8523.c
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@@ -85,6 +85,18 @@ static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value)
return 0; 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) static int pcf8523_select_capacitance(struct i2c_client *client, bool high)
{ {
u8 value; u8 value;
@@ -167,6 +179,14 @@ static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
struct i2c_msg msgs[2]; struct i2c_msg msgs[2];
int err; 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].addr = client->addr;
msgs[0].flags = 0; msgs[0].flags = 0;
msgs[0].len = 1; msgs[0].len = 1;
@@ -251,17 +271,13 @@ static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd,
unsigned long arg) unsigned long arg)
{ {
struct i2c_client *client = to_i2c_client(dev); struct i2c_client *client = to_i2c_client(dev);
u8 value; int ret;
int ret = 0, err;
switch (cmd) { switch (cmd) {
case RTC_VL_READ: case RTC_VL_READ:
err = pcf8523_read(client, REG_CONTROL3, &value); ret = pcf8523_voltage_low(client);
if (err < 0) if (ret < 0)
return err; return ret;
if (value & REG_CONTROL3_BLF)
ret = 1;
if (copy_to_user((void __user *)arg, &ret, sizeof(int))) if (copy_to_user((void __user *)arg, &ret, sizeof(int)))
return -EFAULT; return -EFAULT;