rtc: pcf8563: stop caching voltage_low

voltage_low is only updated when reading the time, this means that using
RTC_VL_READ will miss the VL flag if the time has not been read before
using the ioctl. Always read the status from the hardware.

Link: https://lore.kernel.org/r/20191214220259.621996-9-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/rtc/rtc-pcf8563.c b/drivers/rtc/rtc-pcf8563.c
index 026192fc0c2aa46c1cec048298adecc9fa3c3ef8..7fc43950cf6c9f7cc4fc0de385f61e112eed1f32 100644 (file)
--- a/drivers/rtc/rtc-pcf8563.c
+++ b/drivers/rtc/rtc-pcf8563.c
@@ -76,7 +76,6 @@ struct pcf8563 {
         * 1970...2069.
         */
        int c_polarity; /* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
-       int voltage_low; /* incicates if a low_voltage was detected */
 
        struct i2c_client *client;
 #ifdef CONFIG_COMMON_CLK
@@ -208,7 +207,6 @@ static int pcf8563_rtc_read_time(struct device *dev, struct rtc_time *tm)
                return err;
 
        if (buf[PCF8563_REG_SC] & PCF8563_SC_LV) {
-               pcf8563->voltage_low = 1;
                dev_err(&client->dev,
                        "low voltage detected, date/time is not reliable.\n");
                return -EINVAL;
@@ -278,15 +276,19 @@ static int pcf8563_rtc_set_time(struct device *dev, struct rtc_time *tm)
 
 static int pcf8563_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 {
-       struct pcf8563 *pcf8563 = i2c_get_clientdata(to_i2c_client(dev));
+       struct i2c_client *client = to_i2c_client(dev);
+       int vl, ret;
 
        switch (cmd) {
        case RTC_VL_READ:
-               if (pcf8563->voltage_low)
-                       dev_info(dev, "low voltage detected, date/time is not reliable.\n");
 
-               if (copy_to_user((void __user *)arg, &pcf8563->voltage_low,
-                                       sizeof(int)))
+               ret = i2c_smbus_read_byte_data(client, PCF8563_REG_SC);
+               if (ret < 0)
+                       return ret;
+
+               vl = ret & PCF8563_SC_LV ? 1 : 0;
+
+               if (copy_to_user((void __user *)arg, &vl, sizeof(int)))
                        return -EFAULT;
                return 0;
        default: