RTC: DaVinci RTC driver

This driver features:

* Alarm support.
* Periodic interrupt by using a timer include into the RTC module.
* The update interrupt is not supported by this RTC module.

This driver was tested on a DM365 EVM by using the rtc-test application
from the Documentation/rtc.txt.

Signed-off-by: Miguel Aguilar <miguel.aguilar@ridgerun.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>

3 files changed, 684 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 6a130375943..50ac047cd13 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -620,6 +620,16 @@ config RTC_DRV_NUC900
 
 comment "on-CPU RTC drivers"
 
+config RTC_DRV_DAVINCI
+	tristate "TI DaVinci RTC"
+	depends on ARCH_DAVINCI_DM365
+	help
+	  If you say yes here you get support for the RTC on the
+	  DaVinci platforms (DM365).
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-davinci.
+
 config RTC_DRV_OMAP
 	tristate "TI OMAP1"
 	depends on ARCH_OMAP15XX || ARCH_OMAP16XX || ARCH_OMAP730 || ARCH_DAVINCI_DA8XX
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 44ef194a957..245311a1348 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_RTC_DRV_BQ32K)	+= rtc-bq32k.o
 obj-$(CONFIG_RTC_DRV_BQ4802)	+= rtc-bq4802.o
 obj-$(CONFIG_RTC_DRV_CMOS)	+= rtc-cmos.o
 obj-$(CONFIG_RTC_DRV_COH901331)	+= rtc-coh901331.o
+obj-$(CONFIG_RTC_DRV_DAVINCI)	+= rtc-davinci.o
 obj-$(CONFIG_RTC_DRV_DM355EVM)	+= rtc-dm355evm.o
 obj-$(CONFIG_RTC_DRV_DS1216)	+= rtc-ds1216.o
 obj-$(CONFIG_RTC_DRV_DS1286)	+= rtc-ds1286.o
diff --git a/drivers/rtc/rtc-davinci.c b/drivers/rtc/rtc-davinci.c
new file mode 100644
index 00000000000..92a8f6cacda
--- /dev/null
+++ b/drivers/rtc/rtc-davinci.c
@@ -0,0 +1,673 @@
+/*
+ * DaVinci Power Management and Real Time Clock Driver for TI platforms
+ *
+ * Copyright (C) 2009 Texas Instruments, Inc
+ *
+ * Author: Miguel Aguilar <miguel.aguilar@ridgerun.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.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/ioport.h>
+#include <linux/delay.h>
+#include <linux/spinlock.h>
+#include <linux/rtc.h>
+#include <linux/bcd.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+
+/*
+ * The DaVinci RTC is a simple RTC with the following
+ * Sec: 0 - 59 : BCD count
+ * Min: 0 - 59 : BCD count
+ * Hour: 0 - 23 : BCD count
+ * Day: 0 - 0x7FFF(32767) : Binary count ( Over 89 years )
+ */
+
+/* PRTC interface registers */
+#define DAVINCI_PRTCIF_PID		0x00
+#define PRTCIF_CTLR			0x04
+#define PRTCIF_LDATA			0x08
+#define PRTCIF_UDATA			0x0C
+#define PRTCIF_INTEN			0x10
+#define PRTCIF_INTFLG			0x14
+
+/* PRTCIF_CTLR bit fields */
+#define PRTCIF_CTLR_BUSY		BIT(31)
+#define PRTCIF_CTLR_SIZE		BIT(25)
+#define PRTCIF_CTLR_DIR			BIT(24)
+#define PRTCIF_CTLR_BENU_MSB		BIT(23)
+#define PRTCIF_CTLR_BENU_3RD_BYTE	BIT(22)
+#define PRTCIF_CTLR_BENU_2ND_BYTE	BIT(21)
+#define PRTCIF_CTLR_BENU_LSB		BIT(20)
+#define PRTCIF_CTLR_BENU_MASK		(0x00F00000)
+#define PRTCIF_CTLR_BENL_MSB		BIT(19)
+#define PRTCIF_CTLR_BENL_3RD_BYTE	BIT(18)
+#define PRTCIF_CTLR_BENL_2ND_BYTE	BIT(17)
+#define PRTCIF_CTLR_BENL_LSB		BIT(16)
+#define PRTCIF_CTLR_BENL_MASK		(0x000F0000)
+
+/* PRTCIF_INTEN bit fields */
+#define PRTCIF_INTEN_RTCSS		BIT(1)
+#define PRTCIF_INTEN_RTCIF		BIT(0)
+#define PRTCIF_INTEN_MASK		(PRTCIF_INTEN_RTCSS \
+					| PRTCIF_INTEN_RTCIF)
+
+/* PRTCIF_INTFLG bit fields */
+#define PRTCIF_INTFLG_RTCSS		BIT(1)
+#define PRTCIF_INTFLG_RTCIF		BIT(0)
+#define PRTCIF_INTFLG_MASK		(PRTCIF_INTFLG_RTCSS \
+					| PRTCIF_INTFLG_RTCIF)
+
+/* PRTC subsystem registers */
+#define PRTCSS_RTC_INTC_EXTENA1		(0x0C)
+#define PRTCSS_RTC_CTRL			(0x10)
+#define PRTCSS_RTC_WDT			(0x11)
+#define PRTCSS_RTC_TMR0			(0x12)
+#define PRTCSS_RTC_TMR1			(0x13)
+#define PRTCSS_RTC_CCTRL		(0x14)
+#define PRTCSS_RTC_SEC			(0x15)
+#define PRTCSS_RTC_MIN			(0x16)
+#define PRTCSS_RTC_HOUR			(0x17)
+#define PRTCSS_RTC_DAY0			(0x18)
+#define PRTCSS_RTC_DAY1			(0x19)
+#define PRTCSS_RTC_AMIN			(0x1A)
+#define PRTCSS_RTC_AHOUR		(0x1B)
+#define PRTCSS_RTC_ADAY0		(0x1C)
+#define PRTCSS_RTC_ADAY1		(0x1D)
+#define PRTCSS_RTC_CLKC_CNT		(0x20)
+
+/* PRTCSS_RTC_INTC_EXTENA1 */
+#define PRTCSS_RTC_INTC_EXTENA1_MASK	(0x07)
+
+/* PRTCSS_RTC_CTRL bit fields */
+#define PRTCSS_RTC_CTRL_WDTBUS		BIT(7)
+#define PRTCSS_RTC_CTRL_WEN		BIT(6)
+#define PRTCSS_RTC_CTRL_WDRT		BIT(5)
+#define PRTCSS_RTC_CTRL_WDTFLG		BIT(4)
+#define PRTCSS_RTC_CTRL_TE		BIT(3)
+#define PRTCSS_RTC_CTRL_TIEN		BIT(2)
+#define PRTCSS_RTC_CTRL_TMRFLG		BIT(1)
+#define PRTCSS_RTC_CTRL_TMMD		BIT(0)
+
+/* PRTCSS_RTC_CCTRL bit fields */
+#define PRTCSS_RTC_CCTRL_CALBUSY	BIT(7)
+#define PRTCSS_RTC_CCTRL_DAEN		BIT(5)
+#define PRTCSS_RTC_CCTRL_HAEN		BIT(4)
+#define PRTCSS_RTC_CCTRL_MAEN		BIT(3)
+#define PRTCSS_RTC_CCTRL_ALMFLG		BIT(2)
+#define PRTCSS_RTC_CCTRL_AIEN		BIT(1)
+#define PRTCSS_RTC_CCTRL_CAEN		BIT(0)
+
+static DEFINE_SPINLOCK(davinci_rtc_lock);
+
+struct davinci_rtc {
+	struct rtc_device 		*rtc;
+	void __iomem			*base;
+	resource_size_t			pbase;
+	size_t				base_size;
+	int				irq;
+};
+
+static inline void rtcif_write(struct davinci_rtc *davinci_rtc,
+			       u32 val, u32 addr)
+{
+	writel(val, davinci_rtc->base + addr);
+}
+
+static inline u32 rtcif_read(struct davinci_rtc *davinci_rtc, u32 addr)
+{
+	return readl(davinci_rtc->base + addr);
+}
+
+static inline void rtcif_wait(struct davinci_rtc *davinci_rtc)
+{
+	while (rtcif_read(davinci_rtc, PRTCIF_CTLR) & PRTCIF_CTLR_BUSY)
+		cpu_relax();
+}
+
+static inline void rtcss_write(struct davinci_rtc *davinci_rtc,
+			       unsigned long val, u8 addr)
+{
+	rtcif_wait(davinci_rtc);
+
+	rtcif_write(davinci_rtc, PRTCIF_CTLR_BENL_LSB | addr, PRTCIF_CTLR);
+	rtcif_write(davinci_rtc, val, PRTCIF_LDATA);
+
+	rtcif_wait(davinci_rtc);
+}
+
+static inline u8 rtcss_read(struct davinci_rtc *davinci_rtc, u8 addr)
+{
+	rtcif_wait(davinci_rtc);
+
+	rtcif_write(davinci_rtc, PRTCIF_CTLR_DIR | PRTCIF_CTLR_BENL_LSB | addr,
+		    PRTCIF_CTLR);
+
+	rtcif_wait(davinci_rtc);
+
+	return rtcif_read(davinci_rtc, PRTCIF_LDATA);
+}
+
+static inline void davinci_rtcss_calendar_wait(struct davinci_rtc *davinci_rtc)
+{
+	while (rtcss_read(davinci_rtc, PRTCSS_RTC_CCTRL) &
+	       PRTCSS_RTC_CCTRL_CALBUSY)
+		cpu_relax();
+}
+
+static irqreturn_t davinci_rtc_interrupt(int irq, void *class_dev)
+{
+	struct davinci_rtc *davinci_rtc = class_dev;
+	unsigned long events = 0;
+	u32 irq_flg;
+	u8 alm_irq, tmr_irq;
+	u8 rtc_ctrl, rtc_cctrl;
+	int ret = IRQ_NONE;
+
+	irq_flg = rtcif_read(davinci_rtc, PRTCIF_INTFLG) &
+		  PRTCIF_INTFLG_RTCSS;
+
+	alm_irq = rtcss_read(davinci_rtc, PRTCSS_RTC_CCTRL) &
+		  PRTCSS_RTC_CCTRL_ALMFLG;
+
+	tmr_irq = rtcss_read(davinci_rtc, PRTCSS_RTC_CTRL) &
+		  PRTCSS_RTC_CTRL_TMRFLG;
+
+	if (irq_flg) {
+		if (alm_irq) {
+			events |= RTC_IRQF | RTC_AF;
+			rtc_cctrl = rtcss_read(davinci_rtc, PRTCSS_RTC_CCTRL);
+			rtc_cctrl |=  PRTCSS_RTC_CCTRL_ALMFLG;
+			rtcss_write(davinci_rtc, rtc_cctrl, PRTCSS_RTC_CCTRL);
+		} else if (tmr_irq) {
+			events |= RTC_IRQF | RTC_PF;
+			rtc_ctrl = rtcss_read(davinci_rtc, PRTCSS_RTC_CTRL);
+			rtc_ctrl |=  PRTCSS_RTC_CTRL_TMRFLG;
+			rtcss_write(davinci_rtc, rtc_ctrl, PRTCSS_RTC_CTRL);
+		}
+
+		rtcif_write(davinci_rtc, PRTCIF_INTFLG_RTCSS,
+				    PRTCIF_INTFLG);
+		rtc_update_irq(davinci_rtc->rtc, 1, events);
+
+		ret = IRQ_HANDLED;
+	}
+
+	return ret;
+}
+
+static int
+davinci_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
+{
+	struct davinci_rtc *davinci_rtc = dev_get_drvdata(dev);
+	u8 rtc_ctrl;
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(&davinci_rtc_lock, flags);
+
+	rtc_ctrl = rtcss_read(davinci_rtc, PRTCSS_RTC_CTRL);
+
+	switch (cmd) {
+	case RTC_WIE_ON:
+		rtc_ctrl |= PRTCSS_RTC_CTRL_WEN | PRTCSS_RTC_CTRL_WDTFLG;
+		break;
+	case RTC_WIE_OFF:
+		rtc_ctrl &= ~PRTCSS_RTC_CTRL_WEN;
+		break;
+	case RTC_UIE_OFF:
+	case RTC_UIE_ON:
+		ret = -ENOTTY;
+		break;
+	default:
+		ret = -ENOIOCTLCMD;
+	}
+
+	rtcss_write(davinci_rtc, rtc_ctrl, PRTCSS_RTC_CTRL);
+
+	spin_unlock_irqrestore(&davinci_rtc_lock, flags);
+
+	return ret;
+}
+
+static int convertfromdays(u16 days, struct rtc_time *tm)
+{
+	int tmp_days, year, mon;
+
+	for (year = 2000;; year++) {
+		tmp_days = rtc_year_days(1, 12, year);
+		if (days >= tmp_days)
+			days -= tmp_days;
+		else {
+			for (mon = 0;; mon++) {
+				tmp_days = rtc_month_days(mon, year);
+				if (days >= tmp_days) {
+					days -= tmp_days;
+				} else {
+					tm->tm_year = year - 1900;
+					tm->tm_mon = mon;
+					tm->tm_mday = days + 1;
+					break;
+				}
+			}
+			break;
+		}
+	}
+	return 0;
+}
+
+static int convert2days(u16 *days, struct rtc_time *tm)
+{
+	int i;
+	*days = 0;
+
+	/* epoch == 1900 */
+	if (tm->tm_year < 100 || tm->tm_year > 199)
+		return -EINVAL;
+
+	for (i = 2000; i < 1900 + tm->tm_year; i++)
+		*days += rtc_year_days(1, 12, i);
+
+	*days += rtc_year_days(tm->tm_mday, tm->tm_mon, 1900 + tm->tm_year);
+
+	return 0;
+}
+
+static int davinci_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct davinci_rtc *davinci_rtc = dev_get_drvdata(dev);
+	u16 days = 0;
+	u8 day0, day1;
+	unsigned long flags;
+
+	spin_lock_irqsave(&davinci_rtc_lock, flags);
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	tm->tm_sec = bcd2bin(rtcss_read(davinci_rtc, PRTCSS_RTC_SEC));
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	tm->tm_min = bcd2bin(rtcss_read(davinci_rtc, PRTCSS_RTC_MIN));
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	tm->tm_hour = bcd2bin(rtcss_read(davinci_rtc, PRTCSS_RTC_HOUR));
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	day0 = rtcss_read(davinci_rtc, PRTCSS_RTC_DAY0);
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	day1 = rtcss_read(davinci_rtc, PRTCSS_RTC_DAY1);
+
+	spin_unlock_irqrestore(&davinci_rtc_lock, flags);
+
+	days |= day1;
+	days <<= 8;
+	days |= day0;
+
+	if (convertfromdays(days, tm) < 0)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int davinci_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct davinci_rtc *davinci_rtc = dev_get_drvdata(dev);
+	u16 days;
+	u8 rtc_cctrl;
+	unsigned long flags;
+
+	if (convert2days(&days, tm) < 0)
+		return -EINVAL;
+
+	spin_lock_irqsave(&davinci_rtc_lock, flags);
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	rtcss_write(davinci_rtc, bin2bcd(tm->tm_sec), PRTCSS_RTC_SEC);
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	rtcss_write(davinci_rtc, bin2bcd(tm->tm_min), PRTCSS_RTC_MIN);
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	rtcss_write(davinci_rtc, bin2bcd(tm->tm_hour), PRTCSS_RTC_HOUR);
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	rtcss_write(davinci_rtc, days & 0xFF, PRTCSS_RTC_DAY0);
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	rtcss_write(davinci_rtc, (days & 0xFF00) >> 8, PRTCSS_RTC_DAY1);
+
+	rtc_cctrl = rtcss_read(davinci_rtc, PRTCSS_RTC_CCTRL);
+	rtc_cctrl |= PRTCSS_RTC_CCTRL_CAEN;
+	rtcss_write(davinci_rtc, rtc_cctrl, PRTCSS_RTC_CCTRL);
+
+	spin_unlock_irqrestore(&davinci_rtc_lock, flags);
+
+	return 0;
+}
+
+static int davinci_rtc_alarm_irq_enable(struct device *dev,
+					unsigned int enabled)
+{
+	struct davinci_rtc *davinci_rtc = dev_get_drvdata(dev);
+	unsigned long flags;
+	u8 rtc_cctrl = rtcss_read(davinci_rtc, PRTCSS_RTC_CCTRL);
+
+	spin_lock_irqsave(&davinci_rtc_lock, flags);
+
+	if (enabled)
+		rtc_cctrl |= PRTCSS_RTC_CCTRL_DAEN |
+			     PRTCSS_RTC_CCTRL_HAEN |
+			     PRTCSS_RTC_CCTRL_MAEN |
+			     PRTCSS_RTC_CCTRL_ALMFLG |
+			     PRTCSS_RTC_CCTRL_AIEN;
+	else
+		rtc_cctrl &= ~PRTCSS_RTC_CCTRL_AIEN;
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	rtcss_write(davinci_rtc, rtc_cctrl, PRTCSS_RTC_CCTRL);
+
+	spin_unlock_irqrestore(&davinci_rtc_lock, flags);
+
+	return 0;
+}
+
+static int davinci_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
+{
+	struct davinci_rtc *davinci_rtc = dev_get_drvdata(dev);
+	u16 days = 0;
+	u8 day0, day1;
+	unsigned long flags;
+
+	spin_lock_irqsave(&davinci_rtc_lock, flags);
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	alm->time.tm_min = bcd2bin(rtcss_read(davinci_rtc, PRTCSS_RTC_AMIN));
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	alm->time.tm_hour = bcd2bin(rtcss_read(davinci_rtc, PRTCSS_RTC_AHOUR));
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	day0 = rtcss_read(davinci_rtc, PRTCSS_RTC_ADAY0);
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	day1 = rtcss_read(davinci_rtc, PRTCSS_RTC_ADAY1);
+
+	spin_unlock_irqrestore(&davinci_rtc_lock, flags);
+	days |= day1;
+	days <<= 8;
+	days |= day0;
+
+	if (convertfromdays(days, &alm->time) < 0)
+		return -EINVAL;
+
+	alm->pending = !!(rtcss_read(davinci_rtc,
+			  PRTCSS_RTC_CCTRL) &
+			PRTCSS_RTC_CCTRL_AIEN);
+	alm->enabled = alm->pending && device_may_wakeup(dev);
+
+	return 0;
+}
+
+static int davinci_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
+{
+	struct davinci_rtc *davinci_rtc = dev_get_drvdata(dev);
+	unsigned long flags;
+	u16 days;
+
+	if (alm->time.tm_mday <= 0 && alm->time.tm_mon < 0
+	    && alm->time.tm_year < 0) {
+		struct rtc_time tm;
+		unsigned long now, then;
+
+		davinci_rtc_read_time(dev, &tm);
+		rtc_tm_to_time(&tm, &now);
+
+		alm->time.tm_mday = tm.tm_mday;
+		alm->time.tm_mon = tm.tm_mon;
+		alm->time.tm_year = tm.tm_year;
+		rtc_tm_to_time(&alm->time, &then);
+
+		if (then < now) {
+			rtc_time_to_tm(now + 24 * 60 * 60, &tm);
+			alm->time.tm_mday = tm.tm_mday;
+			alm->time.tm_mon = tm.tm_mon;
+			alm->time.tm_year = tm.tm_year;
+		}
+	}
+
+	if (convert2days(&days, &alm->time) < 0)
+		return -EINVAL;
+
+	spin_lock_irqsave(&davinci_rtc_lock, flags);
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	rtcss_write(davinci_rtc, bin2bcd(alm->time.tm_min), PRTCSS_RTC_AMIN);
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	rtcss_write(davinci_rtc, bin2bcd(alm->time.tm_hour), PRTCSS_RTC_AHOUR);
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	rtcss_write(davinci_rtc, days & 0xFF, PRTCSS_RTC_ADAY0);
+
+	davinci_rtcss_calendar_wait(davinci_rtc);
+	rtcss_write(davinci_rtc, (days & 0xFF00) >> 8, PRTCSS_RTC_ADAY1);
+
+	spin_unlock_irqrestore(&davinci_rtc_lock, flags);
+
+	return 0;
+}
+
+static int davinci_rtc_irq_set_state(struct device *dev, int enabled)
+{
+	struct davinci_rtc *davinci_rtc = dev_get_drvdata(dev);
+	unsigned long flags;
+	u8 rtc_ctrl;
+
+	spin_lock_irqsave(&davinci_rtc_lock, flags);
+
+	rtc_ctrl = rtcss_read(davinci_rtc, PRTCSS_RTC_CTRL);
+
+	if (enabled) {
+		while (rtcss_read(davinci_rtc, PRTCSS_RTC_CTRL)
+		       & PRTCSS_RTC_CTRL_WDTBUS)
+			cpu_relax();
+
+		rtc_ctrl |= PRTCSS_RTC_CTRL_TE;
+		rtcss_write(davinci_rtc, rtc_ctrl, PRTCSS_RTC_CTRL);
+
+		rtcss_write(davinci_rtc, 0x0, PRTCSS_RTC_CLKC_CNT);
+
+		rtc_ctrl |= PRTCSS_RTC_CTRL_TIEN |
+			    PRTCSS_RTC_CTRL_TMMD |
+			    PRTCSS_RTC_CTRL_TMRFLG;
+	} else
+		rtc_ctrl &= ~PRTCSS_RTC_CTRL_TIEN;
+
+	rtcss_write(davinci_rtc, rtc_ctrl, PRTCSS_RTC_CTRL);
+
+	spin_unlock_irqrestore(&davinci_rtc_lock, flags);
+
+	return 0;
+}
+
+static int davinci_rtc_irq_set_freq(struct device *dev, int freq)
+{
+	struct davinci_rtc *davinci_rtc = dev_get_drvdata(dev);
+	unsigned long flags;
+	u16 tmr_counter = (0x8000 >> (ffs(freq) - 1));
+
+	spin_lock_irqsave(&davinci_rtc_lock, flags);
+
+	rtcss_write(davinci_rtc, tmr_counter & 0xFF, PRTCSS_RTC_TMR0);
+	rtcss_write(davinci_rtc, (tmr_counter & 0xFF00) >> 8, PRTCSS_RTC_TMR1);
+
+	spin_unlock_irqrestore(&davinci_rtc_lock, flags);
+
+	return 0;
+}
+
+static struct rtc_class_ops davinci_rtc_ops = {
+	.ioctl			= davinci_rtc_ioctl,
+	.read_time		= davinci_rtc_read_time,
+	.set_time		= davinci_rtc_set_time,
+	.alarm_irq_enable	= davinci_rtc_alarm_irq_enable,
+	.read_alarm		= davinci_rtc_read_alarm,
+	.set_alarm		= davinci_rtc_set_alarm,
+	.irq_set_state		= davinci_rtc_irq_set_state,
+	.irq_set_freq		= davinci_rtc_irq_set_freq,
+};
+
+static int __init davinci_rtc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct davinci_rtc *davinci_rtc;
+	struct resource *res, *mem;
+	int ret = 0;
+
+	davinci_rtc = kzalloc(sizeof(struct davinci_rtc), GFP_KERNEL);
+	if (!davinci_rtc) {
+		dev_dbg(dev, "could not allocate memory for private data\n");
+		return -ENOMEM;
+	}
+
+	davinci_rtc->irq = platform_get_irq(pdev, 0);
+	if (davinci_rtc->irq < 0) {
+		dev_err(dev, "no RTC irq\n");
+		ret = davinci_rtc->irq;
+		goto fail1;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(dev, "no mem resource\n");
+		ret = -EINVAL;
+		goto fail1;
+	}
+
+	davinci_rtc->pbase = res->start;
+	davinci_rtc->base_size = resource_size(res);
+
+	mem = request_mem_region(davinci_rtc->pbase, davinci_rtc->base_size,
+				 pdev->name);
+	if (!mem) {
+		dev_err(dev, "RTC registers at %08x are not free\n",
+			davinci_rtc->pbase);
+		ret = -EBUSY;
+		goto fail1;
+	}
+
+	davinci_rtc->base = ioremap(davinci_rtc->pbase, davinci_rtc->base_size);
+	if (!davinci_rtc->base) {
+		dev_err(dev, "unable to ioremap MEM resource\n");
+		ret = -ENOMEM;
+		goto fail2;
+	}
+
+	davinci_rtc->rtc = rtc_device_register(pdev->name, &pdev->dev,
+				    &davinci_rtc_ops, THIS_MODULE);
+	if (IS_ERR(davinci_rtc->rtc)) {
+		dev_err(dev, "unable to register RTC device, err %ld\n",
+				PTR_ERR(davinci_rtc->rtc));
+		goto fail3;
+	}
+
+	rtcif_write(davinci_rtc, PRTCIF_INTFLG_RTCSS, PRTCIF_INTFLG);
+	rtcif_write(davinci_rtc, 0, PRTCIF_INTEN);
+	rtcss_write(davinci_rtc, 0, PRTCSS_RTC_INTC_EXTENA1);
+
+	rtcss_write(davinci_rtc, 0, PRTCSS_RTC_CTRL);
+	rtcss_write(davinci_rtc, 0, PRTCSS_RTC_CCTRL);
+
+	ret = request_irq(davinci_rtc->irq, davinci_rtc_interrupt,
+			  IRQF_DISABLED, "davinci_rtc", davinci_rtc);
+	if (ret < 0) {
+		dev_err(dev, "unable to register davinci RTC interrupt\n");
+		goto fail4;
+	}
+
+	/* Enable interrupts */
+	rtcif_write(davinci_rtc, PRTCIF_INTEN_RTCSS, PRTCIF_INTEN);
+	rtcss_write(davinci_rtc, PRTCSS_RTC_INTC_EXTENA1_MASK,
+			    PRTCSS_RTC_INTC_EXTENA1);
+
+	rtcss_write(davinci_rtc, PRTCSS_RTC_CCTRL_CAEN, PRTCSS_RTC_CCTRL);
+
+	platform_set_drvdata(pdev, davinci_rtc);
+
+	device_init_wakeup(&pdev->dev, 0);
+
+	return 0;
+
+fail4:
+	rtc_device_unregister(davinci_rtc->rtc);
+fail3:
+	iounmap(davinci_rtc->base);
+fail2:
+	release_mem_region(davinci_rtc->pbase, davinci_rtc->base_size);
+fail1:
+	kfree(davinci_rtc);
+
+	return ret;
+}
+
+static int __devexit davinci_rtc_remove(struct platform_device *pdev)
+{
+	struct davinci_rtc *davinci_rtc = platform_get_drvdata(pdev);
+
+	device_init_wakeup(&pdev->dev, 0);
+
+	rtcif_write(davinci_rtc, 0, PRTCIF_INTEN);
+
+	free_irq(davinci_rtc->irq, davinci_rtc);
+
+	rtc_device_unregister(davinci_rtc->rtc);
+
+	iounmap(davinci_rtc->base);
+	release_mem_region(davinci_rtc->pbase, davinci_rtc->base_size);
+
+	platform_set_drvdata(pdev, NULL);
+
+	kfree(davinci_rtc);
+
+	return 0;
+}
+
+static struct platform_driver davinci_rtc_driver = {
+	.probe		= davinci_rtc_probe,
+	.remove		= __devexit_p(davinci_rtc_remove),
+	.driver		= {
+		.name = "rtc_davinci",
+		.owner = THIS_MODULE,
+	},
+};
+
+static int __init rtc_init(void)
+{
+	return platform_driver_probe(&davinci_rtc_driver, davinci_rtc_probe);
+}
+module_init(rtc_init);
+
+static void __exit rtc_exit(void)
+{
+	platform_driver_unregister(&davinci_rtc_driver);
+}
+module_exit(rtc_exit);
+
+MODULE_AUTHOR("Miguel Aguilar <miguel.aguilar@ridgerun.com>");
+MODULE_DESCRIPTION("Texas Instruments DaVinci PRTC Driver");
+MODULE_LICENSE("GPL");