Patchwork [v2] rtc: tps65910: Add RTC driver for TPS65910 PMIC RTC

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Submitter Venu Byravarasu
Date Aug. 1, 2012, 6:22 a.m.
Message ID <1343802157-13600-1-git-send-email-vbyravarasu@nvidia.com>
Download mbox | patch
Permalink /patch/174391/
State New
Headers show

Comments

Venu Byravarasu - Aug. 1, 2012, 6:22 a.m.
TPS65910 PMIC is a MFD with RTC as one of the device.
Adding RTC driver for supporting RTC device present
inside TPS65910 PMIC.

Only support for RTC alarm is implemented as part of this patch.

Signed-off-by: Venu Byravarasu <vbyravarasu@nvidia.com>
---
delta from patch v1:

1. Added const qualifier to rtc_class_ops
2. Removed some of the local variables initialization
3. Passing string "rtc-tps65910" to devm_request_threaded_irq.
4. Changed driver name from "tps65910-rtc" to "rtc-tps65910"

 drivers/rtc/Kconfig          |   10 ++
 drivers/rtc/Makefile         |    1 +
 drivers/rtc/rtc-tps65910.c   |  353 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/tps65910.h |   10 ++
 4 files changed, 374 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-tps65910.c
Matthias Kaehlcke - Aug. 1, 2012, 8:18 p.m.
hi,

El Wed, Aug 01, 2012 at 11:52:37AM +0530 Venu Byravarasu ha dit:

> TPS65910 PMIC is a MFD with RTC as one of the device.
> Adding RTC driver for supporting RTC device present
> inside TPS65910 PMIC.
> 
> Only support for RTC alarm is implemented as part of this patch.
> 
> Signed-off-by: Venu Byravarasu <vbyravarasu@nvidia.com>
> ---

...

> +static irqreturn_t tps65910_rtc_interrupt(int irq, void *rtc)
> +{
> +	struct device *dev = rtc;
> +	unsigned long events = 0;
> +	struct tps65910 *tps = dev_get_drvdata(dev->parent);
> +	struct tps65910_rtc *tps_rtc = dev_get_drvdata(dev);
>
> ...
>
> +static int __devinit tps65910_rtc_probe(struct platform_device *pdev)
> +{
>
> ...
>
> +	ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
> +		tps65910_rtc_interrupt, IRQF_TRIGGER_LOW,
> +		"rtc-tps65910", &pdev->dev);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "IRQ is not free.\n");
> +		return ret;
> +	}
> +	device_init_wakeup(&pdev->dev, 1);
> +
> +	tps_rtc->rtc = rtc_device_register(pdev->name, &pdev->dev,
> +		&tps65910_rtc_ops, THIS_MODULE);
> +	if (IS_ERR(tps_rtc->rtc)) {
> +		ret = PTR_ERR(tps_rtc->rtc);
> +		dev_err(&pdev->dev, "RTC device register: err %d\n", ret);
> +		return ret;
> +	}
> +
> +	platform_set_drvdata(pdev, tps_rtc);

the interrupt should be requested after this call. otherwise
tps65910_rtc_interrupt() could be executed before the RTC device is
registered and the driver data set. normally this shouldn't happen as
the RTC interrupts are disabled after reset, but the interrupts could
have been enabled for example by the bootloader

best regards
Venu Byravarasu - Aug. 2, 2012, 4:58 a.m.
> -----Original Message-----
> From: Matthias Kaehlcke [mailto:matthias.list@kaehlcke.net]
> Sent: Thursday, August 02, 2012 1:48 AM
> To: Venu Byravarasu
> Cc: a.zummo@towertech.it; sameo@linux.intel.com;
> broonie@opensource.wolfsonmicro.com; Laxman Dewangan;
> kyle.manna@fuel7.com; sboyd@codeaurora.org; rtc-
> linux@googlegroups.com; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v2] rtc: tps65910: Add RTC driver for TPS65910 PMIC RTC
> 
> hi,
> 
> El Wed, Aug 01, 2012 at 11:52:37AM +0530 Venu Byravarasu ha dit:
> 
> > TPS65910 PMIC is a MFD with RTC as one of the device.
> > Adding RTC driver for supporting RTC device present
> > inside TPS65910 PMIC.
> >
> > Only support for RTC alarm is implemented as part of this patch.
> >
> > Signed-off-by: Venu Byravarasu <vbyravarasu@nvidia.com>
> > ---
> 
> ...
> 
> > +static irqreturn_t tps65910_rtc_interrupt(int irq, void *rtc)
> > +{
> > +	struct device *dev = rtc;
> > +	unsigned long events = 0;
> > +	struct tps65910 *tps = dev_get_drvdata(dev->parent);
> > +	struct tps65910_rtc *tps_rtc = dev_get_drvdata(dev);
> >
> > ...
> >
> > +static int __devinit tps65910_rtc_probe(struct platform_device *pdev)
> > +{
> >
> > ...
> >
> > +	ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
> > +		tps65910_rtc_interrupt, IRQF_TRIGGER_LOW,
> > +		"rtc-tps65910", &pdev->dev);
> > +	if (ret < 0) {
> > +		dev_err(&pdev->dev, "IRQ is not free.\n");
> > +		return ret;
> > +	}
> > +	device_init_wakeup(&pdev->dev, 1);
> > +
> > +	tps_rtc->rtc = rtc_device_register(pdev->name, &pdev->dev,
> > +		&tps65910_rtc_ops, THIS_MODULE);
> > +	if (IS_ERR(tps_rtc->rtc)) {
> > +		ret = PTR_ERR(tps_rtc->rtc);
> > +		dev_err(&pdev->dev, "RTC device register: err %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	platform_set_drvdata(pdev, tps_rtc);
> 
> the interrupt should be requested after this call. otherwise
> tps65910_rtc_interrupt() could be executed before the RTC device is
> registered and the driver data set. normally this shouldn't happen as
> the RTC interrupts are disabled after reset, but the interrupts could
> have been enabled for example by the bootloader

Hi Matthias,

Thanks for your comments.
All pending RTC interrupts are being cleared in probe, before enabling RTC itself.
Hence chances of stray interrupts from boot loader cannot cause any trouble here.

The only possible way of getting interrupt by kernel driver is by enabling 
tps65910_rtc_alarm_irq_enable() && setting alarm time using tps65910_rtc_set_alarm.
However before probe gets completed as these two APIs will not get 
called together by the client, I do not see any false interrupt getting generated.

Please let me know if I miss something.

Thanks,
Venu
> 
> best regards
> 
> --
> Matthias Kaehlcke
> Embedded Linux Developer
> Amsterdam
> 
>       Anyone who has never made a mistake has never tried anything new
>                             (Albert Einstein)
>                                                                  .''`.
>     using free software / Debian GNU/Linux | http://debian.org  : :'  :
>                                                                 `. `'`
> gpg --keyserver pgp.mit.edu --recv-keys 47D8E5D4                  `-
Matthias Kaehlcke - Aug. 2, 2012, 8 p.m.
Hi Venu,

thanks for you reply

El Thu, Aug 02, 2012 at 10:28:47AM +0530 Venu Byravarasu ha dit:

> > -----Original Message-----
> > From: Matthias Kaehlcke [mailto:matthias.list@kaehlcke.net]
> > Sent: Thursday, August 02, 2012 1:48 AM
> > To: Venu Byravarasu
> > Cc: a.zummo@towertech.it; sameo@linux.intel.com;
> > broonie@opensource.wolfsonmicro.com; Laxman Dewangan;
> > kyle.manna@fuel7.com; sboyd@codeaurora.org; rtc-
> > linux@googlegroups.com; linux-kernel@vger.kernel.org
> > Subject: Re: [PATCH v2] rtc: tps65910: Add RTC driver for TPS65910 PMIC RTC
> > 
> > hi,
> > 
> > El Wed, Aug 01, 2012 at 11:52:37AM +0530 Venu Byravarasu ha dit:
> > 
> > > TPS65910 PMIC is a MFD with RTC as one of the device.
> > > Adding RTC driver for supporting RTC device present
> > > inside TPS65910 PMIC.
> > >
> > > Only support for RTC alarm is implemented as part of this patch.
> > >
> > > Signed-off-by: Venu Byravarasu <vbyravarasu@nvidia.com>
> > > ---
> > 
> > ...
> > 
> > > +static irqreturn_t tps65910_rtc_interrupt(int irq, void *rtc)
> > > +{
> > > +	struct device *dev = rtc;
> > > +	unsigned long events = 0;
> > > +	struct tps65910 *tps = dev_get_drvdata(dev->parent);
> > > +	struct tps65910_rtc *tps_rtc = dev_get_drvdata(dev);
> > >
> > > ...
> > >
> > > +static int __devinit tps65910_rtc_probe(struct platform_device *pdev)
> > > +{
> > >
> > > ...
> > >
> > > +	ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
> > > +		tps65910_rtc_interrupt, IRQF_TRIGGER_LOW,
> > > +		"rtc-tps65910", &pdev->dev);
> > > +	if (ret < 0) {
> > > +		dev_err(&pdev->dev, "IRQ is not free.\n");
> > > +		return ret;
> > > +	}
> > > +	device_init_wakeup(&pdev->dev, 1);
> > > +
> > > +	tps_rtc->rtc = rtc_device_register(pdev->name, &pdev->dev,
> > > +		&tps65910_rtc_ops, THIS_MODULE);
> > > +	if (IS_ERR(tps_rtc->rtc)) {
> > > +		ret = PTR_ERR(tps_rtc->rtc);
> > > +		dev_err(&pdev->dev, "RTC device register: err %d\n", ret);
> > > +		return ret;
> > > +	}
> > > +
> > > +	platform_set_drvdata(pdev, tps_rtc);
> > 
> > the interrupt should be requested after this call. otherwise
> > tps65910_rtc_interrupt() could be executed before the RTC device is
> > registered and the driver data set. normally this shouldn't happen as
> > the RTC interrupts are disabled after reset, but the interrupts could
> > have been enabled for example by the bootloader
> 
> Hi Matthias,
> 
> Thanks for your comments.
> All pending RTC interrupts are being cleared in probe, before enabling RTC itself.
> Hence chances of stray interrupts from boot loader cannot cause any trouble here.
> 
> The only possible way of getting interrupt by kernel driver is by enabling 
> tps65910_rtc_alarm_irq_enable() && setting alarm time using tps65910_rtc_set_alarm.
> However before probe gets completed as these two APIs will not get 
> called together by the client, I do not see any false interrupt getting generated.

i was thinking in the periodic interrupts, but now noticed that the
driver only registers to the alarm interrupts, so this is not a
problem

kind regards

Patch

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index fabc99a..b4f1234 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -333,6 +333,16 @@  config RTC_DRV_TWL4030
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-twl.
 
+config RTC_DRV_TPS65910
+	tristate "TI TPS65910 RTC driver"
+	depends on RTC_CLASS && MFD_TPS65910
+	help
+	  If you say yes here you get support for the RTC on the
+	  TPS65910 chips.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-tps65910.
+
 config RTC_DRV_S35390A
 	tristate "Seiko Instruments S-35390A"
 	select BITREVERSE
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 0d5b2b6..3b596af 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -105,6 +105,7 @@  obj-$(CONFIG_RTC_DRV_TEGRA)	+= rtc-tegra.o
 obj-$(CONFIG_RTC_DRV_TEST)	+= rtc-test.o
 obj-$(CONFIG_RTC_DRV_TILE)	+= rtc-tile.o
 obj-$(CONFIG_RTC_DRV_TWL4030)	+= rtc-twl.o
+obj-$(CONFIG_RTC_DRV_TPS65910)	+= rtc-tps65910.o
 obj-$(CONFIG_RTC_DRV_TX4939)	+= rtc-tx4939.o
 obj-$(CONFIG_RTC_DRV_V3020)	+= rtc-v3020.o
 obj-$(CONFIG_RTC_DRV_VR41XX)	+= rtc-vr41xx.o
diff --git a/drivers/rtc/rtc-tps65910.c b/drivers/rtc/rtc-tps65910.c
new file mode 100644
index 0000000..1b8991c
--- /dev/null
+++ b/drivers/rtc/rtc-tps65910.c
@@ -0,0 +1,353 @@ 
+/*
+ * rtc-tps65910.c -- TPS65910 Real Time Clock interface
+ *
+ * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
+ * Author: Venu Byravarasu <vbyravarasu@nvidia.com>
+ *
+ * Based on original TI driver rtc-twl.c
+ *   Copyright (C) 2007 MontaVista Software, Inc
+ *   Author: Alexandre Rusev <source@mvista.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/rtc.h>
+#include <linux/bcd.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/tps65910.h>
+
+struct tps65910_rtc {
+	struct rtc_device	*rtc;
+	/* To store the list of enabled interrupts */
+	u32 irqstat;
+};
+
+/* Total number of RTC registers needed to set time*/
+#define NUM_TIME_REGS	(TPS65910_YEARS - TPS65910_SECONDS + 1)
+
+static int tps65910_rtc_alarm_irq_enable(struct device *dev, unsigned enabled)
+{
+	struct tps65910 *tps = dev_get_drvdata(dev->parent);
+	u8 val = 0;
+
+	if (enabled)
+		val = TPS65910_RTC_INTERRUPTS_IT_ALARM;
+
+	return regmap_write(tps->regmap, TPS65910_RTC_INTERRUPTS, val);
+}
+
+/*
+ * Gets current tps65910 RTC time and date parameters.
+ *
+ * The RTC's time/alarm representation is not what gmtime(3) requires
+ * Linux to use:
+ *
+ *  - Months are 1..12 vs Linux 0-11
+ *  - Years are 0..99 vs Linux 1900..N (we assume 21st century)
+ */
+static int tps65910_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	unsigned char rtc_data[NUM_TIME_REGS];
+	struct tps65910 *tps = dev_get_drvdata(dev->parent);
+	int ret;
+
+	/* Copy RTC counting registers to static registers or latches */
+	ret = regmap_update_bits(tps->regmap, TPS65910_RTC_CTRL,
+		TPS65910_RTC_CTRL_GET_TIME, TPS65910_RTC_CTRL_GET_TIME);
+	if (ret < 0) {
+		dev_err(dev, "RTC CTRL reg update failed with err:%d\n", ret);
+		return ret;
+	}
+
+	ret = regmap_bulk_read(tps->regmap, TPS65910_SECONDS, rtc_data,
+		NUM_TIME_REGS);
+	if (ret < 0) {
+		dev_err(dev, "reading from RTC failed with err:%d\n", ret);
+		return ret;
+	}
+
+	tm->tm_sec = bcd2bin(rtc_data[0]);
+	tm->tm_min = bcd2bin(rtc_data[1]);
+	tm->tm_hour = bcd2bin(rtc_data[2]);
+	tm->tm_mday = bcd2bin(rtc_data[3]);
+	tm->tm_mon = bcd2bin(rtc_data[4]) - 1;
+	tm->tm_year = bcd2bin(rtc_data[5]) + 100;
+
+	return ret;
+}
+
+static int tps65910_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	unsigned char rtc_data[NUM_TIME_REGS];
+	struct tps65910 *tps = dev_get_drvdata(dev->parent);
+	int ret;
+
+	rtc_data[0] = bin2bcd(tm->tm_sec);
+	rtc_data[1] = bin2bcd(tm->tm_min);
+	rtc_data[2] = bin2bcd(tm->tm_hour);
+	rtc_data[3] = bin2bcd(tm->tm_mday);
+	rtc_data[4] = bin2bcd(tm->tm_mon + 1);
+	rtc_data[5] = bin2bcd(tm->tm_year - 100);
+
+	/* Stop RTC while updating the RTC time registers */
+	ret = regmap_update_bits(tps->regmap, TPS65910_RTC_CTRL,
+		TPS65910_RTC_CTRL_STOP_RTC, 0);
+	if (ret < 0) {
+		dev_err(dev, "RTC stop failed with err:%d\n", ret);
+		return ret;
+	}
+
+	/* update all the time registers in one shot */
+	ret = regmap_bulk_write(tps->regmap, TPS65910_SECONDS, rtc_data,
+		NUM_TIME_REGS);
+	if (ret < 0) {
+		dev_err(dev, "rtc_set_time error %d\n", ret);
+		return ret;
+	}
+
+	/* Start back RTC */
+	ret = regmap_update_bits(tps->regmap, TPS65910_RTC_CTRL,
+		TPS65910_RTC_CTRL_STOP_RTC, 1);
+	if (ret < 0)
+		dev_err(dev, "RTC start failed with err:%d\n", ret);
+
+	return ret;
+}
+
+/*
+ * Gets current tps65910 RTC alarm time.
+ */
+static int tps65910_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
+{
+	unsigned char alarm_data[NUM_TIME_REGS];
+	u32 int_val;
+	struct tps65910 *tps = dev_get_drvdata(dev->parent);
+	int ret;
+
+	ret = regmap_bulk_read(tps->regmap, TPS65910_SECONDS, alarm_data,
+		NUM_TIME_REGS);
+	if (ret < 0) {
+		dev_err(dev, "rtc_read_alarm error %d\n", ret);
+		return ret;
+	}
+
+	alm->time.tm_sec = bcd2bin(alarm_data[0]);
+	alm->time.tm_min = bcd2bin(alarm_data[1]);
+	alm->time.tm_hour = bcd2bin(alarm_data[2]);
+	alm->time.tm_mday = bcd2bin(alarm_data[3]);
+	alm->time.tm_mon = bcd2bin(alarm_data[4]) - 1;
+	alm->time.tm_year = bcd2bin(alarm_data[5]) + 100;
+
+	ret = regmap_read(tps->regmap, TPS65910_RTC_INTERRUPTS, &int_val);
+	if (ret < 0)
+		return ret;
+
+	if (int_val & TPS65910_RTC_INTERRUPTS_IT_ALARM)
+		alm->enabled = 1;
+
+	return ret;
+}
+
+static int tps65910_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
+{
+	unsigned char alarm_data[NUM_TIME_REGS];
+	struct tps65910 *tps = dev_get_drvdata(dev->parent);
+	int ret;
+
+	ret = tps65910_rtc_alarm_irq_enable(dev, 0);
+	if (ret)
+		return ret;
+
+	alarm_data[0] = bin2bcd(alm->time.tm_sec);
+	alarm_data[1] = bin2bcd(alm->time.tm_min);
+	alarm_data[2] = bin2bcd(alm->time.tm_hour);
+	alarm_data[3] = bin2bcd(alm->time.tm_mday);
+	alarm_data[4] = bin2bcd(alm->time.tm_mon + 1);
+	alarm_data[5] = bin2bcd(alm->time.tm_year - 100);
+
+	/* update all the alarm registers in one shot */
+	ret = regmap_bulk_write(tps->regmap, TPS65910_ALARM_SECONDS,
+		alarm_data, NUM_TIME_REGS);
+	if (ret) {
+		dev_err(dev, "rtc_set_alarm error %d\n", ret);
+		return ret;
+	}
+
+	if (alm->enabled)
+		ret = tps65910_rtc_alarm_irq_enable(dev, 1);
+
+	return ret;
+}
+
+static irqreturn_t tps65910_rtc_interrupt(int irq, void *rtc)
+{
+	struct device *dev = rtc;
+	unsigned long events = 0;
+	struct tps65910 *tps = dev_get_drvdata(dev->parent);
+	struct tps65910_rtc *tps_rtc = dev_get_drvdata(dev);
+	int ret;
+	u32 rtc_reg;
+
+	ret = regmap_read(tps->regmap, TPS65910_RTC_STATUS, &rtc_reg);
+	if (ret)
+		return IRQ_NONE;
+
+	if (rtc_reg & TPS65910_RTC_STATUS_ALARM)
+		events = RTC_IRQF | RTC_AF;
+
+	ret = regmap_write(tps->regmap, TPS65910_RTC_STATUS, rtc_reg);
+	if (ret)
+		return IRQ_NONE;
+
+	/* Notify RTC core on event */
+	rtc_update_irq(tps_rtc->rtc, 1, events);
+
+	return IRQ_HANDLED;
+}
+
+static const struct rtc_class_ops tps65910_rtc_ops = {
+	.read_time	= tps65910_rtc_read_time,
+	.set_time	= tps65910_rtc_set_time,
+	.read_alarm	= tps65910_rtc_read_alarm,
+	.set_alarm	= tps65910_rtc_set_alarm,
+	.alarm_irq_enable = tps65910_rtc_alarm_irq_enable,
+};
+
+static int __devinit tps65910_rtc_probe(struct platform_device *pdev)
+{
+	struct tps65910 *tps65910 = NULL;
+	struct tps65910_rtc *tps_rtc = NULL;
+	struct tps65910_board *pmic_plat_data;
+	int ret;
+	int irq;
+	u32 rtc_reg;
+
+	tps65910 = dev_get_drvdata(pdev->dev.parent);
+
+	tps_rtc = devm_kzalloc(&pdev->dev, sizeof(struct tps65910_rtc),
+			GFP_KERNEL);
+	if (!tps_rtc)
+		return -ENOMEM;
+
+	/* Clear pending interrupts */
+	ret = regmap_read(tps65910->regmap, TPS65910_RTC_STATUS, &rtc_reg);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_write(tps65910->regmap, TPS65910_RTC_STATUS, rtc_reg);
+	if (ret < 0)
+		return ret;
+
+	dev_dbg(&pdev->dev, "Enabling rtc-tps65910.\n");
+	rtc_reg = TPS65910_RTC_CTRL_STOP_RTC;
+	ret = regmap_write(tps65910->regmap, TPS65910_RTC_CTRL, rtc_reg);
+	if (ret < 0)
+		return ret;
+
+	pmic_plat_data = dev_get_platdata(tps65910->dev);
+	irq = pmic_plat_data->irq_base;
+	if (irq <= 0) {
+		dev_warn(&pdev->dev, "Wake up is not possible as irq = %d\n",
+			irq);
+		return ret;
+	}
+
+	irq += TPS65910_IRQ_RTC_ALARM;
+	ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
+		tps65910_rtc_interrupt, IRQF_TRIGGER_LOW,
+		"rtc-tps65910", &pdev->dev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "IRQ is not free.\n");
+		return ret;
+	}
+	device_init_wakeup(&pdev->dev, 1);
+
+	tps_rtc->rtc = rtc_device_register(pdev->name, &pdev->dev,
+		&tps65910_rtc_ops, THIS_MODULE);
+	if (IS_ERR(tps_rtc->rtc)) {
+		ret = PTR_ERR(tps_rtc->rtc);
+		dev_err(&pdev->dev, "RTC device register: err %d\n", ret);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, tps_rtc);
+
+	return 0;
+}
+
+/*
+ * Disable tps65910 RTC interrupts.
+ * Sets status flag to free.
+ */
+static int __devexit tps65910_rtc_remove(struct platform_device *pdev)
+{
+	/* leave rtc running, but disable irqs */
+	struct rtc_device *rtc = platform_get_drvdata(pdev);
+
+	tps65910_rtc_alarm_irq_enable(&rtc->dev, 0);
+
+	rtc_device_unregister(rtc);
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+
+static int tps65910_rtc_suspend(struct platform_device *pdev,
+		pm_message_t state)
+{
+	struct tps65910 *tps = dev_get_drvdata(pdev->dev.parent);
+	u8 alarm = TPS65910_RTC_INTERRUPTS_IT_ALARM;
+	int ret;
+
+	/* Store current list of enabled interrupts*/
+	ret = regmap_read(tps->regmap, TPS65910_RTC_INTERRUPTS,
+		&tps->rtc.irqstat);
+	if (ret < 0)
+		return ret;
+
+	/* Enable RTC ALARM interrupt only */
+	return regmap_write(tps->regmap, TPS65910_RTC_INTERRUPTS, alarm);
+}
+
+static int tps65910_rtc_resume(struct platform_device *pdev)
+{
+	struct tps65910 *tps = dev_get_drvdata(pdev->dev.parent);
+
+	/* Restore list of enabled interrupts before suspend */
+	return regmap_write(tps->regmap, TPS65910_RTC_INTERRUPTS,
+		tps->rtc.irqstat);
+}
+
+static const struct dev_pm_ops tps65910_rtc_pm_ops = {
+	.suspend	= tps65910_rtc_suspend,
+	.resume		= tps65910_rtc_resume,
+};
+
+#define DEV_PM_OPS     (&tps65910_rtc_pm_ops)
+#else
+#define DEV_PM_OPS     NULL
+#endif
+
+static struct platform_driver tps65910_rtc_driver = {
+	.probe		= tps65910_rtc_probe,
+	.remove		= __devexit_p(tps65910_rtc_remove),
+	.driver		= {
+		.owner	= THIS_MODULE,
+		.name	= "rtc-tps65910",
+		.pm	= DEV_PM_OPS,
+	},
+};
+
+module_platform_driver(tps65910_rtc_driver);
+MODULE_ALIAS("platform:rtc-tps65910");
+MODULE_AUTHOR("Venu Byravarasu <vbyravarasu@nvidia.com>");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/mfd/tps65910.h b/include/linux/mfd/tps65910.h
index 9bf8767..ba2eb25 100644
--- a/include/linux/mfd/tps65910.h
+++ b/include/linux/mfd/tps65910.h
@@ -132,6 +132,16 @@ 
  *
  */
 
+/* RTC_CTRL_REG bitfields */
+#define TPS65910_RTC_CTRL_STOP_RTC			0x01 /*0=stop, 1=run */
+#define TPS65910_RTC_CTRL_GET_TIME			0x40
+
+/* RTC_STATUS_REG bitfields */
+#define TPS65910_RTC_STATUS_ALARM               0x40
+
+/* RTC_INTERRUPTS_REG bitfields */
+#define TPS65910_RTC_INTERRUPTS_EVERY           0x03
+#define TPS65910_RTC_INTERRUPTS_IT_ALARM        0x08
 
 /*Register BCK1  (0x80) register.RegisterDescription */
 #define BCK1_BCKUP_MASK					0xFF