rtc/ab8500: add calibration attribute to AB8500 RTC (dda367ac) · Commits · 戴 / test

Documentation/ABI/testing/sysfs-class-rtc-rtc0-device-rtc_calibration

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Original line number	Diff line number	Diff line
		What: Attribute for calibrating ST-Ericsson AB8500 Real Time Clock
		Date: Oct 2011
		KernelVersion: 3.0
		Contact: Mark Godfrey <mark.godfrey@stericsson.com>
		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.

drivers/rtc/rtc-ab8500.c

+112 −0

Original line number	Diff line number	Diff line
		@@ -258,6 +258,109 @@ static int ab8500_rtc_set_alarm(struct device dev, struct rtc_wkalrm alarm)
		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. -128 (0x80) is not permitted because the AB8500 uses
		* a sign-bit rather than two's complement, so 0x80 is just another
		* representation of zero.
		*/
		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 +430,13 @@ static int __devinit ab8500_rtc_probe(struct platform_device *pdev)

		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 +445,8 @@ static int __devexit ab8500_rtc_remove(struct platform_device *pdev)
		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);

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