drivers/rtc/rtc-pcf8563.c: add RTC_VL_READ/RTC_VL_CLR ioctl feature

Changes are based on arch/cris/arch-v10/drivers/pcf8563.c

[akpm@linux-foundation.org: fix sparse warning]
Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Mikael Starvik <starvik@axis.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Wu Fengguang <wfg@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/rtc/rtc-pcf8563.c b/drivers/rtc/rtc-pcf8563.c
index bc0677d..97a3284 100644 (file)
--- a/drivers/rtc/rtc-pcf8563.c
+++ b/drivers/rtc/rtc-pcf8563.c
@@ -64,6 +64,7 @@ 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 */
 };
 
 /*
@@ -86,9 +87,11 @@ static int pcf8563_get_datetime(struct i2c_client *client, struct rtc_time *tm)
                return -EIO;
        }
 
-       if (buf[PCF8563_REG_SC] & PCF8563_SC_LV)
+       if (buf[PCF8563_REG_SC] & PCF8563_SC_LV) {
+               pcf8563->voltage_low = 1;
                dev_info(&client->dev,
                        "low voltage detected, date/time is not reliable.\n");
+       }
 
        dev_dbg(&client->dev,
                "%s: raw data is st1=%02x, st2=%02x, sec=%02x, min=%02x, hr=%02x, "
@@ -173,6 +176,44 @@ static int pcf8563_set_datetime(struct i2c_client *client, struct rtc_time *tm)
        return 0;
 }
 
+#ifdef CONFIG_RTC_INTF_DEV
+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 rtc_time tm;
+
+       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)))
+                       return -EFAULT;
+               return 0;
+       case RTC_VL_CLR:
+               /*
+                * Clear the VL bit in the seconds register in case
+                * the time has not been set already (which would
+                * have cleared it). This does not really matter
+                * because of the cached voltage_low value but do it
+                * anyway for consistency.
+                */
+               if (pcf8563_get_datetime(to_i2c_client(dev), &tm))
+                       pcf8563_set_datetime(to_i2c_client(dev), &tm);
+
+               /* Clear the cached value. */
+               pcf8563->voltage_low = 0;
+
+               return 0;
+       default:
+               return -ENOIOCTLCMD;
+       }
+}
+#else
+#define pcf8563_rtc_ioctl NULL
+#endif
+
 static int pcf8563_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
        return pcf8563_get_datetime(to_i2c_client(dev), tm);
@@ -184,6 +225,7 @@ static int pcf8563_rtc_set_time(struct device *dev, struct rtc_time *tm)
 }
 
 static const struct rtc_class_ops pcf8563_rtc_ops = {
+       .ioctl          = pcf8563_rtc_ioctl,
        .read_time      = pcf8563_rtc_read_time,
        .set_time       = pcf8563_rtc_set_time,
 };