Patchwork [V3] drivers: rtc: Add support for Qualcomm PMIC8xxx RTC

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Submitter Anirudh Ghayal
Date May 26, 2011, 5:15 a.m.
Message ID <1306386935-8806-1-git-send-email-aghayal@codeaurora.org>
Download mbox | patch
Permalink /patch/97499/
State New
Headers show

Comments

Anirudh Ghayal - May 26, 2011, 5:15 a.m.
This patch adds support for PMIC8xxx based RTC.
PMIC8xxx is Qualcomm's power management IC that
internally houses an RTC module. This driver
communicates with the PMIC module over SSBI bus.

Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>
---
 drivers/rtc/Kconfig            |   10 +
 drivers/rtc/Makefile           |    1 +
 drivers/rtc/rtc-pm8xxx.c       |  557 ++++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/pm8xxx/rtc.h |   25 ++
 4 files changed, 593 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-pm8xxx.c
 create mode 100644 include/linux/mfd/pm8xxx/rtc.h
Stephen Boyd - May 26, 2011, 5:37 p.m.
On 5/25/2011 10:15 PM, Anirudh Ghayal wrote:
> diff --git a/drivers/rtc/rtc-pm8xxx.c b/drivers/rtc/rtc-pm8xxx.c
> new file mode 100644
> index 0000000..4694c4e
> --- /dev/null
> +++ b/drivers/rtc/rtc-pm8xxx.c
> +
> +/**
> + * struct pm8xxx_rtc	rtc driver internal structure

This is missing a dash '-'.

> +static int pm8xxx_read_wrapper(struct pm8xxx_rtc *rtc_dd, u8 *rtc_val,
> +		int base, int count)
> +{
> +	int i, rc;
> +	struct device *parent = rtc_dd->rtc_dev->parent;
> +
> +	for (i = 0; i < count; i++) {
> +		rc = pm8xxx_readb(parent, base + i, &rtc_val[i]);
> +		if (rc < 0) {
> +			dev_err(rtc_dd->rtc_dev, "PMIC read failed\n");

I still think these printks are useless when you already have better
printks at the call sites on the error path.

> +			return rc;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int pm8xxx_write_wrapper(struct pm8xxx_rtc *rtc_dd, u8 *rtc_val,
> +		int base, int count)
> +{
> +	int i, rc;
> +	struct device *parent = rtc_dd->rtc_dev->parent;
> +
> +	for (i = 0; i < count; i++) {
> +		rc = pm8xxx_writeb(parent, base + i, rtc_val[i]);
> +		if (rc < 0) {
> +			dev_err(rtc_dd->rtc_dev, "PMIC write failed\n");
> +			return rc;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * Steps to write the RTC registers.
> + * 1. Disable alarm if enabled.
> + * 2. Write 0x00 to LSB.
> + * 3. Write Byte[1], Byte[2], Byte[3] then Byte[0].
> + * 4. Enable alarm if disabled in step 1.
> + */
> +static int
> +pm8xxx_rtc_set_time(struct device *dev, struct rtc_time *tm)
> +{
> +	int rc, i;
> +	unsigned long secs, irq_flags;
> +	u8 value[NUM_8_BIT_RTC_REGS], reg = 0, alarm_enabled = 0, ctrl_reg;
> +	struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
> +
> +	rtc_tm_to_time(tm, &secs);
> +
> +	for (i = 0; i < NUM_8_BIT_RTC_REGS; i++) {
> +		value[i] = secs & 0xFF;
> +		secs >>= 8;
> +	}
> +
> +	dev_dbg(dev, "Seconds value to be written to RTC = %lu\n", secs);
> +
> +	spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);
> +	ctrl_reg = rtc_dd->ctrl_reg;
> +
> +	if (ctrl_reg & PM8xxx_RTC_ALARM_ENABLE) {
> +		alarm_enabled = 1;
> +		ctrl_reg &= ~PM8xxx_RTC_ALARM_ENABLE;
> +		rc = pm8xxx_write_wrapper(rtc_dd, &ctrl_reg, rtc_dd->rtc_base,
> +				1);
> +		if (rc < 0) {
> +			dev_err(dev, "Write to RTC control register "
> +								"failed\n");
> +			goto rtc_rw_fail;
> +		}
> +		rtc_dd->ctrl_reg = ctrl_reg;
> +	} else
> +		spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
> +
> +	/* Write 0 to Byte[0] */
> +	reg = 0;
> +	rc = pm8xxx_write_wrapper(rtc_dd, &reg, rtc_dd->rtc_write_base, 1);
> +	if (rc < 0) {
> +		dev_err(dev, "Write to RTC write data register failed\n");
> +		goto rtc_rw_fail;
> +	}
> +
> +	/* Write Byte[1], Byte[2], Byte[3] */
> +	rc = pm8xxx_write_wrapper(rtc_dd, value + 1,
> +					rtc_dd->rtc_write_base + 1, 3);
> +	if (rc < 0) {
> +		dev_err(dev, "Write to RTC write data register failed\n");
> +		goto rtc_rw_fail;
> +	}
> +
> +	/* Write Byte[0] */
> +	rc = pm8xxx_write_wrapper(rtc_dd, value, rtc_dd->rtc_write_base, 1);
> +	if (rc < 0) {
> +		dev_err(dev, "Write to RTC write data register failed\n");
> +		goto rtc_rw_fail;
> +	}
> +
> +	if (alarm_enabled) {
> +		ctrl_reg |= PM8xxx_RTC_ALARM_ENABLE;
> +		rc = pm8xxx_write_wrapper(rtc_dd, &ctrl_reg, rtc_dd->rtc_base,
> +									1);
> +		if (rc < 0) {
> +			dev_err(dev, "Write to RTC control register "
> +								"failed\n");
> +			goto rtc_rw_fail;
> +		}
> +		rtc_dd->ctrl_reg = ctrl_reg;
> +	}
> +
> +rtc_rw_fail:
> +	if (alarm_enabled)
> +		spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
> +

This could be simplified by putting the label inside the if and then
putting the spin_unlock at the end of the if. You would save a branch.
Not sure it really matters though since the compiler should be doing it
anyway.

Is it really that bad to take the lock all the time? It would simplify
this function a bit if you did.

If you fix the kernel-doc error you can add a

Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Kenneth Heitke - May 26, 2011, 10:22 p.m.
On 05/26/2011 11:37 AM, Stephen Boyd wrote:
> On 5/25/2011 10:15 PM, Anirudh Ghayal wrote:
>> diff --git a/drivers/rtc/rtc-pm8xxx.c b/drivers/rtc/rtc-pm8xxx.c
>> new file mode 100644
>> index 0000000..4694c4e
>> --- /dev/null
>> +++ b/drivers/rtc/rtc-pm8xxx.c
>> +
>> +/**
>> + * struct pm8xxx_rtc	rtc driver internal structure
>
> This is missing a dash '-'.
>
>> +static int pm8xxx_read_wrapper(struct pm8xxx_rtc *rtc_dd, u8 *rtc_val,
>> +		int base, int count)
>> +{
>> +	int i, rc;
>> +	struct device *parent = rtc_dd->rtc_dev->parent;
>> +
>> +	for (i = 0; i<  count; i++) {
>> +		rc = pm8xxx_readb(parent, base + i,&rtc_val[i]);
>> +		if (rc<  0) {
>> +			dev_err(rtc_dd->rtc_dev, "PMIC read failed\n");
>
> I still think these printks are useless when you already have better
> printks at the call sites on the error path.

I actually don't mind seeing the entire error flow in the log. 
pm8xxx_readb() might report a failure but it is sometimes help to know 
who the caller was that may have triggered the error.

Patch

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index e187887..39b7032 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -985,6 +985,16 @@  config RTC_DRV_LPC32XX
 	  This driver can also be buillt as a module. If so, the module
 	  will be called rtc-lpc32xx.
 
+config RTC_DRV_PM8XXX
+	tristate "Qualcomm PMIC8XXX RTC"
+	depends on MFD_PM8XXX
+	help
+	  If you say yes here you get support for the
+	  Qualcomm PMIC8XXX RTC.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called rtc-pm8xxx.
+
 config RTC_DRV_TEGRA
 	tristate "NVIDIA Tegra Internal RTC driver"
 	depends on RTC_CLASS && ARCH_TEGRA
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index ca91c3c..f13337c 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -74,6 +74,7 @@  obj-$(CONFIG_RTC_DRV_PCF2123)	+= rtc-pcf2123.o
 obj-$(CONFIG_RTC_DRV_PCF50633)	+= rtc-pcf50633.o
 obj-$(CONFIG_RTC_DRV_PL030)	+= rtc-pl030.o
 obj-$(CONFIG_RTC_DRV_PL031)	+= rtc-pl031.o
+obj-$(CONFIG_RTC_DRV_PM8XXX)	+= rtc-pm8xxx.o
 obj-$(CONFIG_RTC_DRV_PS3)	+= rtc-ps3.o
 obj-$(CONFIG_RTC_DRV_PXA)	+= rtc-pxa.o
 obj-$(CONFIG_RTC_DRV_R9701)	+= rtc-r9701.o
diff --git a/drivers/rtc/rtc-pm8xxx.c b/drivers/rtc/rtc-pm8xxx.c
new file mode 100644
index 0000000..4694c4e
--- /dev/null
+++ b/drivers/rtc/rtc-pm8xxx.c
@@ -0,0 +1,557 @@ 
+/* Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/rtc.h>
+#include <linux/pm.h>
+#include <linux/slab.h>
+#include<linux/spinlock.h>
+
+#include <linux/mfd/pm8xxx/core.h>
+#include <linux/mfd/pm8xxx/rtc.h>
+
+
+/* RTC Register offsets from RTC CTRL REG */
+#define PM8XXX_ALARM_CTRL_OFFSET	0x01
+#define PM8XXX_RTC_WRITE_OFFSET		0x02
+#define PM8XXX_RTC_READ_OFFSET		0x06
+#define PM8XXX_ALARM_RW_OFFSET		0x0A
+
+/* RTC_CTRL register bit fields */
+#define PM8xxx_RTC_ENABLE		BIT(7)
+#define PM8xxx_RTC_ALARM_ENABLE		BIT(1)
+#define PM8xxx_RTC_ALARM_CLEAR		BIT(0)
+
+#define NUM_8_BIT_RTC_REGS		0x4
+
+/**
+ * struct pm8xxx_rtc	rtc driver internal structure
+ * @rtc:		rtc device for this driver.
+ * @rtc_alarm_irq:	rtc alarm irq number.
+ * @rtc_base:		address of rtc control register.
+ * @rtc_read_base:	base address of read registers.
+ * @rtc_write_base:	base address of write registers.
+ * @alarm_rw_base:	base address of alarm registers.
+ * @ctrl_reg:		rtc control register.
+ * @rtc_dev:		device structure.
+ * @ctrl_reg_lock:	spinlock protecting access to ctrl_reg.
+ */
+
+struct pm8xxx_rtc {
+	struct rtc_device *rtc;
+	int rtc_alarm_irq;
+	int rtc_base;
+	int rtc_read_base;
+	int rtc_write_base;
+	int alarm_rw_base;
+	u8  ctrl_reg;
+	struct device *rtc_dev;
+	spinlock_t ctrl_reg_lock;
+};
+
+/*
+ * The RTC registers need to be read/written one byte at a time. This is a
+ * hardware limitation.
+ */
+
+static int pm8xxx_read_wrapper(struct pm8xxx_rtc *rtc_dd, u8 *rtc_val,
+		int base, int count)
+{
+	int i, rc;
+	struct device *parent = rtc_dd->rtc_dev->parent;
+
+	for (i = 0; i < count; i++) {
+		rc = pm8xxx_readb(parent, base + i, &rtc_val[i]);
+		if (rc < 0) {
+			dev_err(rtc_dd->rtc_dev, "PMIC read failed\n");
+			return rc;
+		}
+	}
+
+	return 0;
+}
+
+static int pm8xxx_write_wrapper(struct pm8xxx_rtc *rtc_dd, u8 *rtc_val,
+		int base, int count)
+{
+	int i, rc;
+	struct device *parent = rtc_dd->rtc_dev->parent;
+
+	for (i = 0; i < count; i++) {
+		rc = pm8xxx_writeb(parent, base + i, rtc_val[i]);
+		if (rc < 0) {
+			dev_err(rtc_dd->rtc_dev, "PMIC write failed\n");
+			return rc;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Steps to write the RTC registers.
+ * 1. Disable alarm if enabled.
+ * 2. Write 0x00 to LSB.
+ * 3. Write Byte[1], Byte[2], Byte[3] then Byte[0].
+ * 4. Enable alarm if disabled in step 1.
+ */
+static int
+pm8xxx_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	int rc, i;
+	unsigned long secs, irq_flags;
+	u8 value[NUM_8_BIT_RTC_REGS], reg = 0, alarm_enabled = 0, ctrl_reg;
+	struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
+
+	rtc_tm_to_time(tm, &secs);
+
+	for (i = 0; i < NUM_8_BIT_RTC_REGS; i++) {
+		value[i] = secs & 0xFF;
+		secs >>= 8;
+	}
+
+	dev_dbg(dev, "Seconds value to be written to RTC = %lu\n", secs);
+
+	spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);
+	ctrl_reg = rtc_dd->ctrl_reg;
+
+	if (ctrl_reg & PM8xxx_RTC_ALARM_ENABLE) {
+		alarm_enabled = 1;
+		ctrl_reg &= ~PM8xxx_RTC_ALARM_ENABLE;
+		rc = pm8xxx_write_wrapper(rtc_dd, &ctrl_reg, rtc_dd->rtc_base,
+				1);
+		if (rc < 0) {
+			dev_err(dev, "Write to RTC control register "
+								"failed\n");
+			goto rtc_rw_fail;
+		}
+		rtc_dd->ctrl_reg = ctrl_reg;
+	} else
+		spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
+
+	/* Write 0 to Byte[0] */
+	reg = 0;
+	rc = pm8xxx_write_wrapper(rtc_dd, &reg, rtc_dd->rtc_write_base, 1);
+	if (rc < 0) {
+		dev_err(dev, "Write to RTC write data register failed\n");
+		goto rtc_rw_fail;
+	}
+
+	/* Write Byte[1], Byte[2], Byte[3] */
+	rc = pm8xxx_write_wrapper(rtc_dd, value + 1,
+					rtc_dd->rtc_write_base + 1, 3);
+	if (rc < 0) {
+		dev_err(dev, "Write to RTC write data register failed\n");
+		goto rtc_rw_fail;
+	}
+
+	/* Write Byte[0] */
+	rc = pm8xxx_write_wrapper(rtc_dd, value, rtc_dd->rtc_write_base, 1);
+	if (rc < 0) {
+		dev_err(dev, "Write to RTC write data register failed\n");
+		goto rtc_rw_fail;
+	}
+
+	if (alarm_enabled) {
+		ctrl_reg |= PM8xxx_RTC_ALARM_ENABLE;
+		rc = pm8xxx_write_wrapper(rtc_dd, &ctrl_reg, rtc_dd->rtc_base,
+									1);
+		if (rc < 0) {
+			dev_err(dev, "Write to RTC control register "
+								"failed\n");
+			goto rtc_rw_fail;
+		}
+		rtc_dd->ctrl_reg = ctrl_reg;
+	}
+
+rtc_rw_fail:
+	if (alarm_enabled)
+		spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
+
+	return rc;
+}
+
+static int
+pm8xxx_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	int rc;
+	u8 value[NUM_8_BIT_RTC_REGS], reg;
+	unsigned long secs;
+	struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
+
+	rc = pm8xxx_read_wrapper(rtc_dd, value, rtc_dd->rtc_read_base,
+							NUM_8_BIT_RTC_REGS);
+	if (rc < 0) {
+		dev_err(dev, "RTC read data register failed\n");
+		return rc;
+	}
+
+	/*
+	 * Read the LSB again and check if there has been a carry over.
+	 * If there is, redo the read operation.
+	 */
+	rc = pm8xxx_read_wrapper(rtc_dd, &reg, rtc_dd->rtc_read_base, 1);
+	if (rc < 0) {
+		dev_err(dev, "RTC read data register failed\n");
+		return rc;
+	}
+
+	if (unlikely(reg < value[0])) {
+		rc = pm8xxx_read_wrapper(rtc_dd, value,
+				rtc_dd->rtc_read_base, NUM_8_BIT_RTC_REGS);
+		if (rc < 0) {
+			dev_err(dev, "RTC read data register failed\n");
+			return rc;
+		}
+	}
+
+	secs = value[0] | (value[1] << 8) | (value[2] << 16) | (value[3] << 24);
+
+	rtc_time_to_tm(secs, tm);
+
+	rc = rtc_valid_tm(tm);
+	if (rc < 0) {
+		dev_err(dev, "Invalid time read from RTC\n");
+		return rc;
+	}
+
+	dev_dbg(dev, "secs = %lu, h:m:s == %d:%d:%d, d/m/y = %d/%d/%d\n",
+				secs, tm->tm_hour, tm->tm_min, tm->tm_sec,
+				tm->tm_mday, tm->tm_mon, tm->tm_year);
+
+	return 0;
+}
+
+static int
+pm8xxx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	int rc, i;
+	u8 value[NUM_8_BIT_RTC_REGS], ctrl_reg;
+	unsigned long secs, irq_flags;
+	struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
+
+	rtc_tm_to_time(&alarm->time, &secs);
+
+	for (i = 0; i < NUM_8_BIT_RTC_REGS; i++) {
+		value[i] = secs & 0xFF;
+		secs >>= 8;
+	}
+
+	spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);
+
+	rc = pm8xxx_write_wrapper(rtc_dd, value, rtc_dd->alarm_rw_base,
+							NUM_8_BIT_RTC_REGS);
+	if (rc < 0) {
+		dev_err(dev, "Write to RTC ALARM register failed\n");
+		goto rtc_rw_fail;
+	}
+
+	ctrl_reg = rtc_dd->ctrl_reg;
+	ctrl_reg = alarm->enabled ? (ctrl_reg | PM8xxx_RTC_ALARM_ENABLE) :
+					(ctrl_reg & ~PM8xxx_RTC_ALARM_ENABLE);
+
+	rc = pm8xxx_write_wrapper(rtc_dd, &ctrl_reg, rtc_dd->rtc_base, 1);
+	if (rc < 0) {
+		dev_err(dev, "Write to RTC control register failed\n");
+		goto rtc_rw_fail;
+	}
+
+	rtc_dd->ctrl_reg = ctrl_reg;
+
+	dev_dbg(dev, "Alarm Set for h:r:s=%d:%d:%d, d/m/y=%d/%d/%d\n",
+				alarm->time.tm_hour, alarm->time.tm_min,
+				alarm->time.tm_sec, alarm->time.tm_mday,
+				alarm->time.tm_mon, alarm->time.tm_year);
+rtc_rw_fail:
+	spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
+	return rc;
+}
+
+static int
+pm8xxx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	int rc;
+	u8 value[NUM_8_BIT_RTC_REGS];
+	unsigned long secs;
+	struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
+
+	rc = pm8xxx_read_wrapper(rtc_dd, value, rtc_dd->alarm_rw_base,
+			NUM_8_BIT_RTC_REGS);
+	if (rc < 0) {
+		dev_err(dev, "RTC alarm time read failed\n");
+		return rc;
+	}
+
+	secs = value[0] | (value[1] << 8) | (value[2] << 16) | (value[3] << 24);
+
+	rtc_time_to_tm(secs, &alarm->time);
+
+	rc = rtc_valid_tm(&alarm->time);
+	if (rc < 0) {
+		dev_err(dev, "Invalid alarm time read from RTC\n");
+		return rc;
+	}
+
+	dev_dbg(dev, "Alarm set for - h:r:s=%d:%d:%d, d/m/y=%d/%d/%d\n",
+				alarm->time.tm_hour, alarm->time.tm_min,
+				alarm->time.tm_sec, alarm->time.tm_mday,
+				alarm->time.tm_mon, alarm->time.tm_year);
+
+	return 0;
+}
+
+
+static int
+pm8xxx_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
+{
+	int rc;
+	unsigned long irq_flags;
+	struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
+	u8 ctrl_reg;
+
+	spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);
+	ctrl_reg = rtc_dd->ctrl_reg;
+	ctrl_reg = (enable) ? (ctrl_reg | PM8xxx_RTC_ALARM_ENABLE) :
+				(ctrl_reg & ~PM8xxx_RTC_ALARM_ENABLE);
+
+	rc = pm8xxx_write_wrapper(rtc_dd, &ctrl_reg, rtc_dd->rtc_base, 1);
+	if (rc < 0) {
+		dev_err(dev, "Write to RTC control register failed\n");
+		goto rtc_rw_fail;
+	}
+
+	rtc_dd->ctrl_reg = ctrl_reg;
+
+rtc_rw_fail:
+	spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
+	return rc;
+}
+
+static struct rtc_class_ops pm8xxx_rtc_ops = {
+	.read_time	= pm8xxx_rtc_read_time,
+	.set_alarm	= pm8xxx_rtc_set_alarm,
+	.read_alarm	= pm8xxx_rtc_read_alarm,
+	.alarm_irq_enable = pm8xxx_rtc_alarm_irq_enable,
+};
+
+static irqreturn_t pm8xxx_alarm_trigger(int irq, void *dev_id)
+{
+	struct pm8xxx_rtc *rtc_dd = dev_id;
+	u8 ctrl_reg;
+	int rc;
+	unsigned long irq_flags;
+
+	rtc_update_irq(rtc_dd->rtc, 1, RTC_IRQF | RTC_AF);
+
+	spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);
+
+	/* Clear the alarm enable bit */
+	ctrl_reg = rtc_dd->ctrl_reg;
+	ctrl_reg &= ~PM8xxx_RTC_ALARM_ENABLE;
+
+	rc = pm8xxx_write_wrapper(rtc_dd, &ctrl_reg, rtc_dd->rtc_base, 1);
+	if (rc < 0) {
+		spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
+		dev_err(rtc_dd->rtc_dev, "Write to RTC control register "
+								"failed\n");
+		goto rtc_alarm_handled;
+	}
+
+	rtc_dd->ctrl_reg = ctrl_reg;
+	spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
+
+	/* Clear RTC alarm register */
+	rc = pm8xxx_read_wrapper(rtc_dd, &ctrl_reg, rtc_dd->rtc_base +
+						PM8XXX_ALARM_CTRL_OFFSET, 1);
+	if (rc < 0) {
+		dev_err(rtc_dd->rtc_dev, "RTC Alarm control register read "
+								"failed\n");
+		goto rtc_alarm_handled;
+	}
+
+	ctrl_reg &= ~PM8xxx_RTC_ALARM_CLEAR;
+	rc = pm8xxx_write_wrapper(rtc_dd, &ctrl_reg, rtc_dd->rtc_base +
+						PM8XXX_ALARM_CTRL_OFFSET, 1);
+	if (rc < 0)
+		dev_err(rtc_dd->rtc_dev, "Write to RTC Alarm control register"
+								" failed\n");
+
+rtc_alarm_handled:
+	return IRQ_HANDLED;
+}
+
+static int __devinit pm8xxx_rtc_probe(struct platform_device *pdev)
+{
+	int rc;
+	u8 ctrl_reg;
+	bool rtc_write_enable = false;
+	struct pm8xxx_rtc *rtc_dd;
+	struct resource *rtc_resource;
+	const struct pm8xxx_rtc_platform_data *pdata = mfd_get_data(pdev);
+
+	if (pdata != NULL)
+		rtc_write_enable = pdata->rtc_write_enable;
+
+	rtc_dd = kzalloc(sizeof(*rtc_dd), GFP_KERNEL);
+	if (rtc_dd == NULL) {
+		dev_err(&pdev->dev, "Unable to allocate memory!\n");
+		return -ENOMEM;
+	}
+
+	/* Initialise spinlock to protect RTC control register */
+	spin_lock_init(&rtc_dd->ctrl_reg_lock);
+
+	rtc_dd->rtc_alarm_irq = platform_get_irq(pdev, 0);
+	if (rtc_dd->rtc_alarm_irq < 0) {
+		dev_err(&pdev->dev, "Alarm IRQ resource absent!\n");
+		rc = -ENXIO;
+		goto fail_rtc_enable;
+	}
+
+	rtc_resource = platform_get_resource_byname(pdev, IORESOURCE_IO,
+							"pmic_rtc_base");
+	if (!(rtc_resource && rtc_resource->start)) {
+		dev_err(&pdev->dev, "RTC IO resource absent!\n");
+		rc = -ENXIO;
+		goto fail_rtc_enable;
+	}
+
+	rtc_dd->rtc_base = rtc_resource->start;
+
+	/* Setup RTC register addresses */
+	rtc_dd->rtc_write_base = rtc_dd->rtc_base + PM8XXX_RTC_WRITE_OFFSET;
+	rtc_dd->rtc_read_base = rtc_dd->rtc_base + PM8XXX_RTC_READ_OFFSET;
+	rtc_dd->alarm_rw_base = rtc_dd->rtc_base + PM8XXX_ALARM_RW_OFFSET;
+
+	rtc_dd->rtc_dev = &pdev->dev;
+
+	/* Check if the RTC is on, else turn it on */
+	rc = pm8xxx_read_wrapper(rtc_dd, &ctrl_reg, rtc_dd->rtc_base, 1);
+	if (rc < 0) {
+		dev_err(&pdev->dev, "RTC control register read failed!\n");
+		goto fail_rtc_enable;
+	}
+
+	if (!(ctrl_reg & PM8xxx_RTC_ENABLE)) {
+		ctrl_reg |= PM8xxx_RTC_ENABLE;
+		rc = pm8xxx_write_wrapper(rtc_dd, &ctrl_reg, rtc_dd->rtc_base,
+									1);
+		if (rc < 0) {
+			dev_err(&pdev->dev, "Write to RTC control register "
+								"failed\n");
+			goto fail_rtc_enable;
+		}
+	}
+
+	rtc_dd->ctrl_reg = ctrl_reg;
+	if (rtc_write_enable == true)
+		pm8xxx_rtc_ops.set_time = pm8xxx_rtc_set_time;
+
+	platform_set_drvdata(pdev, rtc_dd);
+
+	/* Register the RTC device */
+	rtc_dd->rtc = rtc_device_register("pm8xxx_rtc", &pdev->dev,
+				&pm8xxx_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc_dd->rtc)) {
+		dev_err(&pdev->dev, "%s: RTC registration failed (%ld)\n",
+					__func__, PTR_ERR(rtc_dd->rtc));
+		rc = PTR_ERR(rtc_dd->rtc);
+		goto fail_rtc_enable;
+	}
+
+	/* Request the alarm IRQ */
+	rc = request_any_context_irq(rtc_dd->rtc_alarm_irq,
+				 pm8xxx_alarm_trigger, IRQF_TRIGGER_RISING,
+				 "pm8xxx_rtc_alarm", rtc_dd);
+	if (rc < 0) {
+		dev_err(&pdev->dev, "Request IRQ failed (%d)\n", rc);
+		goto fail_req_irq;
+	}
+
+	device_init_wakeup(&pdev->dev, 1);
+
+	dev_dbg(&pdev->dev, "Probe success !!\n");
+
+	return 0;
+
+fail_req_irq:
+	rtc_device_unregister(rtc_dd->rtc);
+fail_rtc_enable:
+	platform_set_drvdata(pdev, NULL);
+	kfree(rtc_dd);
+	return rc;
+}
+
+static int __devexit pm8xxx_rtc_remove(struct platform_device *pdev)
+{
+	struct pm8xxx_rtc *rtc_dd = platform_get_drvdata(pdev);
+
+	device_init_wakeup(&pdev->dev, 0);
+	free_irq(rtc_dd->rtc_alarm_irq, rtc_dd);
+	rtc_device_unregister(rtc_dd->rtc);
+	platform_set_drvdata(pdev, NULL);
+	kfree(rtc_dd);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int pm8xxx_rtc_resume(struct device *dev)
+{
+	struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev))
+		disable_irq_wake(rtc_dd->rtc_alarm_irq);
+
+	return 0;
+}
+
+static int pm8xxx_rtc_suspend(struct device *dev)
+{
+	struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev))
+		enable_irq_wake(rtc_dd->rtc_alarm_irq);
+
+	return 0;
+}
+#endif
+
+SIMPLE_DEV_PM_OPS(pm8xxx_rtc_pm_ops, pm8xxx_rtc_suspend, pm8xxx_rtc_resume);
+
+static struct platform_driver pm8xxx_rtc_driver = {
+	.probe		= pm8xxx_rtc_probe,
+	.remove		= __devexit_p(pm8xxx_rtc_remove),
+	.driver	= {
+		.name	= PM8XXX_RTC_DEV_NAME,
+		.owner	= THIS_MODULE,
+		.pm	= &pm8xxx_rtc_pm_ops,
+	},
+};
+
+static int __init pm8xxx_rtc_init(void)
+{
+	return platform_driver_register(&pm8xxx_rtc_driver);
+}
+module_init(pm8xxx_rtc_init);
+
+static void __exit pm8xxx_rtc_exit(void)
+{
+	platform_driver_unregister(&pm8xxx_rtc_driver);
+}
+module_exit(pm8xxx_rtc_exit);
+
+MODULE_ALIAS("platform:rtc-pm8xxx");
+MODULE_DESCRIPTION("PMIC8xxx RTC driver");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Anirudh Ghayal <aghayal@codeaurora.org>");
diff --git a/include/linux/mfd/pm8xxx/rtc.h b/include/linux/mfd/pm8xxx/rtc.h
new file mode 100644
index 0000000..14f1983
--- /dev/null
+++ b/include/linux/mfd/pm8xxx/rtc.h
@@ -0,0 +1,25 @@ 
+/* Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __RTC_PM8XXX_H__
+#define __RTC_PM8XXX_H__
+
+#define PM8XXX_RTC_DEV_NAME     "rtc-pm8xxx"
+/**
+ * struct pm8xxx_rtc_pdata - RTC driver platform data
+ * @rtc_write_enable: variable stating RTC write capability
+ */
+struct pm8xxx_rtc_platform_data {
+	bool rtc_write_enable;
+};
+
+#endif /* __RTC_PM8XXX_H__ */