* [PATCH] rtc: pcf8523: don't return invalid date when battery is low
@ 2018-12-05 15:00 Baruch Siach
2018-12-10 23:47 ` Alexandre Belloni
0 siblings, 1 reply; 2+ messages in thread
From: Baruch Siach @ 2018-12-05 15:00 UTC (permalink / raw)
To: Alessandro Zummo, Alexandre Belloni
Cc: linux-rtc, Jon Nettleton, Erik Čuk, Baruch Siach
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>
---
drivers/rtc/rtc-pcf8523.c | 32 ++++++++++++++++++++++++--------
1 file changed, 24 insertions(+), 8 deletions(-)
diff --git a/drivers/rtc/rtc-pcf8523.c b/drivers/rtc/rtc-pcf8523.c
index 453615f8ac9a..3fcd2cbafc84 100644
--- a/drivers/rtc/rtc-pcf8523.c
+++ b/drivers/rtc/rtc-pcf8523.c
@@ -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;
--
2.19.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] rtc: pcf8523: don't return invalid date when battery is low
2018-12-05 15:00 [PATCH] rtc: pcf8523: don't return invalid date when battery is low Baruch Siach
@ 2018-12-10 23:47 ` Alexandre Belloni
0 siblings, 0 replies; 2+ messages in thread
From: Alexandre Belloni @ 2018-12-10 23:47 UTC (permalink / raw)
To: Baruch Siach; +Cc: Alessandro Zummo, linux-rtc, Jon Nettleton, Erik Čuk
On 05/12/2018 17:00:09+0200, Baruch Siach wrote:
> 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>
> ---
> drivers/rtc/rtc-pcf8523.c | 32 ++++++++++++++++++++++++--------
> 1 file changed, 24 insertions(+), 8 deletions(-)
>
Applied, thanks.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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