The patch titled
Subject: rtc/ab8500: Add calibration attribute to AB8500 RTC
has been added to the -mm tree. Its filename is
rtc-ab8500-add-calibration-attribute-to-ab8500-rtc.patch
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------------------------------------------------------
From: Mark Godfrey <mark.godfrey@xxxxxxxxxxxxxx>
Subject: rtc/ab8500: Add calibration attribute to AB8500 RTC
The rtc_calibration attribute allows user-space to get and set the
AB8500's RtcCalibration register. The AB8500 will then use the value in
this register to compensate for RTC drift every 60 seconds.
Signed-off-by: Mark Godfrey <mark.godfrey@xxxxxxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxxxxxx>
Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/ABI/testing/sysfs-class-rtc-rtc0-device-rtc_calibration | 12 +
drivers/rtc/rtc-ab8500.c | 109 ++++++++++
2 files changed, 121 insertions(+)
diff -puN /dev/null Documentation/ABI/testing/sysfs-class-rtc-rtc0-device-rtc_calibration
--- /dev/null
+++ a/Documentation/ABI/testing/sysfs-class-rtc-rtc0-device-rtc_calibration
@@ -0,0 +1,12 @@
+What: Attribute for calibrating ST-Ericsson AB8500 Real Time Clock
+Date: Oct 2011
+KernelVersion: 3.0
+Contact: Mark Godfrey <mark.godfrey@xxxxxxxxxxxxxx>
+Description: The rtc_calibration attribute allows the userspace to
+ calibrate the AB8500.s 32KHz Real Time Clock.
+ Every 60 seconds the AB8500 will correct the RTC's value
+ by adding to it the value of this attribute.
+ The range of the attribute is -127 to +127 in units of
+ 30.5 micro-seconds (half-parts-per-million of the 32KHz clock)
+Users: The /vendor/st-ericsson/base_utilities/core/rtc_calibration
+ daemon uses this interface.
diff -puN drivers/rtc/rtc-ab8500.c~rtc-ab8500-add-calibration-attribute-to-ab8500-rtc drivers/rtc/rtc-ab8500.c
--- a/drivers/rtc/rtc-ab8500.c~rtc-ab8500-add-calibration-attribute-to-ab8500-rtc
+++ a/drivers/rtc/rtc-ab8500.c
@@ -258,6 +258,106 @@ static int ab8500_rtc_set_alarm(struct d
return ab8500_rtc_irq_enable(dev, alarm->enabled);
}
+
+static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
+{
+ int retval;
+ u8 rtccal = 0;
+
+ /*
+ * Check that the calibration value (which is in units of 0.5 parts-per-million)
+ * is in the AB8500's range for RtcCalibration register.
+ */
+ if ((calibration < -127) || (calibration > 127)) {
+ dev_err(dev, "RtcCalibration value outside permitted range\n");
+ return -EINVAL;
+ }
+
+ /*
+ * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
+ * so need to convert to this sort of representation before writing
+ * into RtcCalibration register...
+ */
+ if (calibration >= 0)
+ rtccal = 0x7F & calibration;
+ else
+ rtccal = ~(calibration -1) | 0x80;
+
+ retval = abx500_set_register_interruptible(dev, AB8500_RTC,
+ AB8500_RTC_CALIB_REG, rtccal);
+
+ return retval;
+}
+
+static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
+{
+ int retval;
+ u8 rtccal = 0;
+
+ retval = abx500_get_register_interruptible(dev, AB8500_RTC,
+ AB8500_RTC_CALIB_REG, &rtccal);
+ if (retval >= 0) {
+ /*
+ * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
+ * so need to convert value from RtcCalibration register into
+ * a two's complement signed value...
+ */
+ if (rtccal & 0x80)
+ *calibration = 0 - (rtccal & 0x7F);
+ else
+ *calibration = 0x7F & rtccal;
+ }
+
+ return retval;
+}
+
+static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ int retval;
+ int calibration = 0;
+
+ if (sscanf(buf, " %i ", &calibration) != 1) {
+ dev_err(dev, "Failed to store RTC calibration attribute\n");
+ return -EINVAL;
+ }
+
+ retval = ab8500_rtc_set_calibration(dev, calibration);
+
+ return retval ? retval : count;
+}
+
+static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ int retval = 0;
+ int calibration = 0;
+
+ retval = ab8500_rtc_get_calibration(dev, &calibration);
+ if (retval < 0) {
+ dev_err(dev, "Failed to read RTC calibration attribute\n");
+ sprintf(buf, "0\n");
+ return retval;
+ }
+
+ return sprintf(buf, "%d\n", calibration);
+}
+
+static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
+ ab8500_sysfs_show_rtc_calibration,
+ ab8500_sysfs_store_rtc_calibration);
+
+static int ab8500_sysfs_rtc_register(struct device *dev)
+{
+ return device_create_file(dev, &dev_attr_rtc_calibration);
+}
+
+static void ab8500_sysfs_rtc_unregister(struct device *dev)
+{
+ device_remove_file(dev, &dev_attr_rtc_calibration);
+}
+
static irqreturn_t rtc_alarm_handler(int irq, void *data)
{
struct rtc_device *rtc = data;
@@ -327,6 +427,13 @@ static int __devinit ab8500_rtc_probe(st
platform_set_drvdata(pdev, rtc);
+
+ err = ab8500_sysfs_rtc_register(&pdev->dev);
+ if (err) {
+ dev_err(&pdev->dev, "sysfs RTC failed to register\n");
+ return err;
+ }
+
return 0;
}
@@ -335,6 +442,8 @@ static int __devexit ab8500_rtc_remove(s
struct rtc_device *rtc = platform_get_drvdata(pdev);
int irq = platform_get_irq_byname(pdev, "ALARM");
+ ab8500_sysfs_rtc_unregister(&pdev->dev);
+
free_irq(irq, rtc);
rtc_device_unregister(rtc);
platform_set_drvdata(pdev, NULL);
_
Subject: Subject: rtc/ab8500: Add calibration attribute to AB8500 RTC
Patches currently in -mm which might be from mark.godfrey@xxxxxxxxxxxxxx are
rtc-ab8500-add-calibration-attribute-to-ab8500-rtc.patch
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