2012-02-14 16:13:56

by Alexander Stein

Subject: [PATCH 1/2 RFC] rtc: Add ioctl to get/clear battery low voltage status

Currently there is no generic way to get the RTC battery status within
an application. So add an ioctl to read the status bit.
The idea is that the bit is set once a low voltage is detected. It stays
there until it is reset using the RTC_VL_CLR ioctl.

Signed-off-by: Alexander Stein <[email protected]>
---
include/linux/rtc.h | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index 93f4d03..1a6ec5f 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -91,6 +91,9 @@ struct rtc_pll_info {
#define RTC_PLL_GET _IOR('p', 0x11, struct rtc_pll_info) /* Get PLL correction */
#define RTC_PLL_SET _IOW('p', 0x12, struct rtc_pll_info) /* Set PLL correction */

+#define RTC_VL_READ _IOR('p', 0x13, int) /* Voltage low detector */
+#define RTC_VL_CLR _IO('p', 0x14) /* Clear voltage low information */
+
/* interrupt flags */
#define RTC_IRQF 0x80 /* Any of the following is active */
#define RTC_PF 0x40 /* Periodic interrupt */
--
1.7.3.4

2012-02-14 16:14:00

by Alexander Stein

Subject: [PATCH 2/2 RFC] rtc-pcf8563: Add RTC_VL_READ/RTC_VL_CLR ioctl feature

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

Signed-off-by: Alexander Stein <[email protected]>
---
drivers/rtc/rtc-pcf8563.c | 44 +++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 43 insertions(+), 1 deletions(-)

diff --git a/drivers/rtc/rtc-pcf8563.c b/drivers/rtc/rtc-pcf8563.c
index 606fdfa..0ba4ae7 100644
--- 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((int *) 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,
};
--
1.7.3.4