rtc: pcf2127: fix reading uninitialized value on RTC_READ_VL ioctl

The flag reported on the RTC_READ_VL ioctl is only initialized when the
date is read out. So the voltage low value doesn't represent reality but
the status at the time the date was read (or 0 if the date was not read
yet).

Moreover when userspace requests a value via an ioctl there is no added
benefit to also make a prosa representation of this (and other) values
appear in the kernel log so remove the calls to dev_info and the driver
data members to track their state.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

1 files changed, 22 insertions, 18 deletions

diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
index a26bae60826c..d83b2d8e3c2b 100644
--- a/drivers/rtc/rtc-pcf2127.c
+++ b/drivers/rtc/rtc-pcf2127.c
@@ -24,7 +24,10 @@
 
 #define PCF2127_REG_CTRL1       (0x00)  /* Control Register 1 */
 #define PCF2127_REG_CTRL2       (0x01)  /* Control Register 2 */
+
 #define PCF2127_REG_CTRL3       (0x02)  /* Control Register 3 */
+#define PCF2127_REG_CTRL3_BLF           BIT(2)
+
 #define PCF2127_REG_SC          (0x03)  /* datetime */
 #define PCF2127_REG_MN          (0x04)
 #define PCF2127_REG_HR          (0x05)
@@ -39,8 +42,6 @@ static struct i2c_driver pcf2127_driver;
 
 struct pcf2127 {
         struct rtc_device *rtc;
-        int voltage_low; /* indicates if a low_voltage was detected */
-        int oscillator_failed; /* OSF was detected and date is unreliable */
 };
 
 /*
@@ -49,7 +50,6 @@ struct pcf2127 {
  */
 static int pcf2127_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 {
-        struct pcf2127 *pcf2127 = i2c_get_clientdata(client);
         unsigned char buf[10] = { PCF2127_REG_CTRL1 };
 
         /* read registers */
@@ -59,18 +59,15 @@ static int pcf2127_get_datetime(struct i2c_client *client, struct rtc_time *tm)
                 return -EIO;
         }
 
-        if (buf[PCF2127_REG_CTRL3] & 0x04) {
-                pcf2127->voltage_low = 1;
+        if (buf[PCF2127_REG_CTRL3] & PCF2127_REG_CTRL3_BLF)
                 dev_info(&client->dev,
                         "low voltage detected, check/replace RTC battery.\n");
-        }
 
         if (buf[PCF2127_REG_SC] & PCF2127_OSF) {
                 /*
                  * no need clear the flag here,
                  * it will be cleared once the new date is saved
                  */
-                pcf2127->oscillator_failed = 1;
                 dev_warn(&client->dev,
                          "oscillator stop detected, date/time is not reliable\n");
                 return -EINVAL;
@@ -107,7 +104,6 @@ static int pcf2127_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 
 static int pcf2127_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 {
-        struct pcf2127 *pcf2127 = i2c_get_clientdata(client);
         unsigned char buf[8];
         int i = 0, err;
 
@@ -141,9 +137,6 @@ static int pcf2127_set_datetime(struct i2c_client *client, struct rtc_time *tm)
                 return -EIO;
         }
 
-        /* clear OSF flag in client data */
-        pcf2127->oscillator_failed = 0;
-
         return 0;
 }
 
@@ -151,17 +144,28 @@ static int pcf2127_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 static int pcf2127_rtc_ioctl(struct device *dev,
                                 unsigned int cmd, unsigned long arg)
 {
-        struct pcf2127 *pcf2127 = i2c_get_clientdata(to_i2c_client(dev));
+        struct i2c_client *client = to_i2c_client(dev);
+        unsigned char buf = PCF2127_REG_CTRL3;
+        int touser;
+        int ret;
 
         switch (cmd) {
         case RTC_VL_READ:
-                if (pcf2127->voltage_low)
-                        dev_info(dev, "low voltage detected, check/replace battery\n");
-                if (pcf2127->oscillator_failed)
-                        dev_info(dev, "oscillator stop detected, date/time is not reliable\n");
+                ret = i2c_master_send(client, &buf, 1);
+                if (!ret)
+                        ret = -EIO;
+                if (ret < 0)
+                        return ret;
+
+                ret = i2c_master_recv(client, &buf, 1);
+                if (!ret)
+                        ret = -EIO;
+                if (ret < 0)
+                        return ret;
+
+                touser = buf & PCF2127_REG_CTRL3_BLF ? 1 : 0;
 
-                if (copy_to_user((void __user *)arg, &pcf2127->voltage_low,
-                                        sizeof(int)))
+                if (copy_to_user((void __user *)arg, &touser, sizeof(int)))
                         return -EFAULT;
                 return 0;
         default: