Linux-RTC Archive on lore.kernel.org
 help / Atom feed
* [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	[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

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, back to index

Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
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

Linux-RTC Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-rtc/0 linux-rtc/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-rtc linux-rtc/ https://lore.kernel.org/linux-rtc \
		linux-rtc@vger.kernel.org linux-rtc@archiver.kernel.org
	public-inbox-index linux-rtc


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-rtc


AGPL code for this site: git clone https://public-inbox.org/ public-inbox