[PATCH] rtc: add support for Freescale SNVS RTC

Ying-Chun Liu (PaulLiu) paul.liu at linaro.org
Mon Mar 19 13:04:29 UTC 2012


From: "Ying-Chun Liu (PaulLiu)" <paul.liu at linaro.org>

This adds an RTC driver for the Low Power (LP) section of SNVS.
It hooks into the /dev/rtc interface and supports ioctl to complete RTC
features. This driver supports device tree bindings.
It only uses the RTC hw in non-secure mode.

Signed-off-by: Anish Trivedi <anish at freescale.com>
Signed-off-by: Eric Miao <eric.miao at linaro.org>
Signed-off-by: Anson Huang <b20788 at freescale.com>
Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu at linaro.org>
Cc: Alessandro Zummo <a.zummo at towertech.it>
Cc: Shawn Guo <shawn.guo at linaro.org>
---
 drivers/rtc/Kconfig    |   11 +
 drivers/rtc/Makefile   |    1 +
 drivers/rtc/rtc-snvs.c |  737 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 749 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-snvs.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 3a125b8..d58f4b7 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -634,6 +634,17 @@ config RTC_MXC
 	   This driver can also be built as a module, if so, the module
 	   will be called "rtc-mxc".
 
+config RTC_DRV_SNVS
+	tristate "Freescale SNVS Real Time Clock"
+	depends on ARCH_MXC
+	depends on RTC_CLASS
+	help
+	   If you say yes here you get support for the Freescale SNVS
+	   Low Power (LP) RTC module.
+
+	   This driver can also be built as a module, if so, the module
+	   will be called "rtc-snvs".
+
 config RTC_DRV_BQ4802
 	tristate "TI BQ4802"
 	help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 6e69823..8b30686 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -93,6 +93,7 @@ obj-$(CONFIG_RTC_DRV_S35390A)	+= rtc-s35390a.o
 obj-$(CONFIG_RTC_DRV_S3C)	+= rtc-s3c.o
 obj-$(CONFIG_RTC_DRV_SA1100)	+= rtc-sa1100.o
 obj-$(CONFIG_RTC_DRV_SH)	+= rtc-sh.o
+obj-$(CONFIG_RTC_DRV_SNVS)	+= rtc-snvs.o
 obj-$(CONFIG_RTC_DRV_SPEAR)	+= rtc-spear.o
 obj-$(CONFIG_RTC_DRV_STARFIRE)	+= rtc-starfire.o
 obj-$(CONFIG_RTC_DRV_STK17TA8)	+= rtc-stk17ta8.o
diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c
new file mode 100644
index 0000000..49ac8a5
--- /dev/null
+++ b/drivers/rtc/rtc-snvs.c
@@ -0,0 +1,737 @@
+/*
+ * Copyright (C) 2011 Freescale Semiconductor, Inc.
+ */
+
+/*
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+/*
+ * Implementation based on rtc-ds1553.c
+ */
+
+/*!
+ * @defgroup RTC Real Time Clock (RTC) Driver
+ */
+/*!
+ * @file rtc-snvs.c
+ * @brief Secure Real Time Clock (SRTC) interface in Freescale's SNVS module
+ *
+ * This file contains Real Time Clock interface for Linux. The Freescale
+ * SNVS module's Low Power (LP) SRTC functionality is utilized in this driver,
+ * in non-secure mode.
+ *
+ * @ingroup RTC
+ */
+
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/rtc.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/uaccess.h>
+#include <linux/io.h>
+#include <linux/sched.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+/* Register definitions */
+#define	SNVS_HPSR	0x14	/* HP Status Register */
+#define	SNVS_LPCR	0x38	/* LP Control Register */
+#define	SNVS_LPSR	0x4C	/* LP Status Register */
+#define	SNVS_LPSRTCMR	0x50	/* LP Secure Real Time Counter MSB Register */
+#define	SNVS_LPSRTCLR	0x54	/* LP Secure Real Time Counter LSB Register */
+#define	SNVS_LPTAR	0x58	/* LP Time Alarm Register */
+#define	SNVS_LPSMCMR	0x5C	/* LP Secure Monotonic Counter MSB Register */
+#define	SNVS_LPSMCLR	0x60	/* LP Secure Monotonic Counter LSB Register */
+#define	SNVS_LPPGDR	0x64	/* LP Power Glitch Detector Register */
+#define	SNVS_LPGPR	0x68	/* LP General Purpose Register */
+
+/* Bit Definitions */
+#define	SNVS_HPSR_SSM_ST_MASK	0x00000F00
+#define	SNVS_HPSR_SSM_ST_SHIFT	8
+
+#define	SNVS_LPCR_SRTC_ENV	(1 << 0)
+#define	SNVS_LPCR_LPTA_EN	(1 << 1)
+#define	SNVS_LPCR_LPWUI_EN	(1 << 3)
+#define	SNVS_LPCR_ALL_INT_EN (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN)
+#define	SNVS_LPSR_LPTA		(1 << 0)
+#define	SNVS_LPPGDR_INIT	0x41736166
+
+/* Other defines */
+#define	SSM_ST_CHECK	0x9
+#define	SSM_ST_NON_SECURE	0xB
+#define	CNTR_TO_SECS_SH 15	/* Converts 47-bit counter to 32-bit seconds */
+
+#define RTC_READ_TIME_47BIT	_IOR('p', 0x20, unsigned long long)
+/* blocks until LPSCMR is set, returns difference */
+#define RTC_WAIT_TIME_SET	_IOR('p', 0x21, int64_t)
+
+struct rtc_drv_data {
+	struct rtc_device *rtc;
+	void __iomem *ioaddr;
+	int irq;
+	bool irq_enable;
+};
+
+static unsigned long rtc_status;
+
+static DEFINE_SPINLOCK(rtc_lock);
+DECLARE_COMPLETION(snvs_completion);
+static int64_t time_diff;
+
+/*!
+ * LP counter register reads should always use this function.
+ * This function reads 2 consective times from LP counter register
+ * until the 2 values match. This is to avoid reading corrupt
+ * value if the counter is in the middle of updating
+ */
+static inline u32 rtc_read_lp_counter(void __iomem *counter_reg)
+{
+	u64 read1, read2;
+	u32 counter_sec;
+
+	do {
+		/* MSB */
+		read1 = readl(counter_reg);
+		read1 <<= 32;
+		/* LSB */
+		read1 |= readl(counter_reg + 4);
+
+		/* MSB */
+		read2 = readl(counter_reg);
+		read2 <<= 32;
+		/* LSB */
+		read2 |= readl(counter_reg + 4);
+	} while (read1 != read2);
+
+	/* Convert 47-bit counter to 32-bit raw second count */
+	counter_sec = (u32) (read1 >> CNTR_TO_SECS_SH);
+
+	return counter_sec;
+}
+
+/*!
+ * This function does write synchronization for writes to the lp srtc block.
+ * To take care of the asynchronous CKIL clock, all writes from the IP domain
+ * will be synchronized to the CKIL domain.
+ */
+static inline void rtc_write_sync_lp(void __iomem *ioaddr)
+{
+	unsigned int i, count1, count2, count3;
+
+	/* Wait for 3 CKIL cycles */
+	for (i = 0; i < 3; i++) {
+
+		/* Do consective reads of LSB of counter to ensure integrity */
+		do {
+			count1 = readl(ioaddr + SNVS_LPSRTCLR);
+			count2 = readl(ioaddr + SNVS_LPSRTCLR);
+		} while (count1 != count2);
+
+		/* Now wait until counter value changes */
+		do {
+			do {
+				count2 = readl(ioaddr + SNVS_LPSRTCLR);
+				count3 = readl(ioaddr + SNVS_LPSRTCLR);
+			} while (count2 != count3);
+		} while (count3 == count1);
+	}
+}
+
+/*!
+ * This function updates the RTC alarm registers and then clears all the
+ * interrupt status bits.
+ *
+ * @param  alrm         the new alarm value to be updated in the RTC
+ *
+ * @return  0 if successful; non-zero otherwise.
+ */
+static int rtc_update_alarm(struct device *dev, struct rtc_time *alrm)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	struct rtc_time alarm_tm, now_tm;
+	unsigned long now, time, lp_cr;
+	int ret;
+
+	now = rtc_read_lp_counter(ioaddr + SNVS_LPSRTCMR);
+	rtc_time_to_tm(now, &now_tm);
+
+	alarm_tm.tm_year = now_tm.tm_year;
+	alarm_tm.tm_mon = now_tm.tm_mon;
+	alarm_tm.tm_mday = now_tm.tm_mday;
+
+	alarm_tm.tm_hour = alrm->tm_hour;
+	alarm_tm.tm_min = alrm->tm_min;
+	alarm_tm.tm_sec = alrm->tm_sec;
+
+	rtc_tm_to_time(&now_tm, &now);
+	rtc_tm_to_time(&alarm_tm, &time);
+
+	if (time < now) {
+		time += 60 * 60 * 24;
+		rtc_time_to_tm(time, &alarm_tm);
+	}
+	ret = rtc_tm_to_time(&alarm_tm, &time);
+
+	/* Have to clear LPTA_EN before programming new alarm time in LPTAR */
+	lp_cr = readl(ioaddr + SNVS_LPCR);
+	writel(lp_cr & ~SNVS_LPCR_LPTA_EN, ioaddr + SNVS_LPCR);
+	rtc_write_sync_lp(ioaddr);
+
+	writel(time, ioaddr + SNVS_LPTAR);
+
+	/* clear alarm interrupt status bit */
+	writel(SNVS_LPSR_LPTA, ioaddr + SNVS_LPSR);
+
+	return ret;
+}
+
+/*!
+ * This function is the RTC interrupt service routine.
+ *
+ * @param  irq          RTC IRQ number
+ * @param  dev_id       device ID which is not used
+ *
+ * @return IRQ_HANDLED as defined in the include/linux/interrupt.h file.
+ */
+static irqreturn_t snvs_rtc_interrupt(int irq, void *dev_id)
+{
+	struct platform_device *pdev = dev_id;
+	struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	u32 lp_status, lp_cr;
+	u32 events = 0;
+
+	lp_status = readl(ioaddr + SNVS_LPSR);
+	lp_cr = readl(ioaddr + SNVS_LPCR);
+
+	/* update irq data & counter */
+	if (lp_status & SNVS_LPSR_LPTA) {
+		if (lp_cr & SNVS_LPCR_LPTA_EN)
+			events |= (RTC_AF | RTC_IRQF);
+
+		/* disable further lp alarm interrupts */
+		lp_cr &= ~(SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
+	}
+
+	/* Update interrupt enables */
+	writel(lp_cr, ioaddr + SNVS_LPCR);
+
+	/* If no interrupts are enabled, turn off interrupts in kernel */
+	if (((lp_cr & SNVS_LPCR_ALL_INT_EN) == 0) && (pdata->irq_enable)) {
+		disable_irq_nosync(pdata->irq);
+		pdata->irq_enable = false;
+	}
+
+	/* clear interrupt status */
+	writel(lp_status, ioaddr + SNVS_LPSR);
+
+	rtc_write_sync_lp(ioaddr);
+	rtc_update_irq(pdata->rtc, 1, events);
+
+	return IRQ_HANDLED;
+}
+
+/*!
+ * This function is used to open the RTC driver.
+ *
+ * @return  0 if successful; non-zero otherwise.
+ */
+static int snvs_rtc_open(struct device *dev)
+{
+	if (test_and_set_bit(1, &rtc_status))
+		return -EBUSY;
+
+	return 0;
+}
+
+/*!
+ * clear all interrupts and release the IRQ
+ */
+static void snvs_rtc_release(struct device *dev)
+{
+	rtc_status = 0;
+}
+
+/*!
+ * This function reads the current RTC time into tm in Gregorian date.
+ *
+ * @param  tm           contains the RTC time value upon return
+ *
+ * @return  0 if successful; non-zero otherwise.
+ */
+static int snvs_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+
+	rtc_time_to_tm(rtc_read_lp_counter(ioaddr + SNVS_LPSRTCMR), tm);
+
+	return 0;
+}
+
+/*!
+ * This function sets the internal RTC time based on tm in Gregorian date.
+ *
+ * @param  tm           the time value to be set in the RTC
+ *
+ * @return  0 if successful; non-zero otherwise.
+ */
+static int snvs_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	unsigned long time;
+	int ret;
+	u32 lp_cr;
+	u64 old_time_47bit, new_time_47bit;
+
+	ret = rtc_tm_to_time(tm, &time);
+	if (ret != 0)
+		return ret;
+
+	old_time_47bit = (((u64) (readl(ioaddr + SNVS_LPSRTCMR) &
+		((0x1 << CNTR_TO_SECS_SH) - 1)) << 32) |
+		((u64) readl(ioaddr + SNVS_LPSRTCLR)));
+
+	/* Disable RTC first */
+	lp_cr = readl(ioaddr + SNVS_LPCR) & ~SNVS_LPCR_SRTC_ENV;
+	writel(lp_cr, ioaddr + SNVS_LPCR);
+	while (readl(ioaddr + SNVS_LPCR) & SNVS_LPCR_SRTC_ENV)
+		;
+
+	/* Write 32-bit time to 47-bit timer, leaving 15 LSBs blank */
+	writel(time << CNTR_TO_SECS_SH, ioaddr + SNVS_LPSRTCLR);
+	writel(time >> (32 - CNTR_TO_SECS_SH), ioaddr + SNVS_LPSRTCMR);
+
+	/* Enable RTC again */
+	writel(lp_cr | SNVS_LPCR_SRTC_ENV, ioaddr + SNVS_LPCR);
+	while (!(readl(ioaddr + SNVS_LPCR) & SNVS_LPCR_SRTC_ENV))
+		;
+
+	rtc_write_sync_lp(ioaddr);
+
+	new_time_47bit = (((u64) (readl(ioaddr + SNVS_LPSRTCMR) &
+		((0x1 << CNTR_TO_SECS_SH) - 1)) << 32) |
+		((u64) readl(ioaddr + SNVS_LPSRTCLR)));
+
+	time_diff = new_time_47bit - old_time_47bit;
+
+	/* signal all waiting threads that time changed */
+	complete_all(&snvs_completion);
+
+	/* allow signalled threads to handle the time change notification */
+	schedule();
+
+	/* reinitialize completion variable */
+	INIT_COMPLETION(snvs_completion);
+
+	return 0;
+}
+
+/*!
+ * This function reads the current alarm value into the passed in \b alrm
+ * argument. It updates the \b alrm's pending field value based on the whether
+ * an alarm interrupt occurs or not.
+ *
+ * @param  alrm         contains the RTC alarm value upon return
+ *
+ * @return  0 if successful; non-zero otherwise.
+ */
+static int snvs_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+
+	rtc_time_to_tm(readl(ioaddr + SNVS_LPTAR), &alrm->time);
+	alrm->pending =
+	    ((readl(ioaddr + SNVS_LPSR) & SNVS_LPSR_LPTA) != 0) ? 1 : 0;
+
+	return 0;
+}
+
+/*!
+ * This function sets the RTC alarm based on passed in alrm.
+ *
+ * @param  alrm         the alarm value to be set in the RTC
+ *
+ * @return  0 if successful; non-zero otherwise.
+ */
+static int snvs_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	unsigned long lock_flags = 0;
+	u32 lp_cr;
+	int ret;
+
+	if (rtc_valid_tm(&alrm->time)) {
+		if (alrm->time.tm_sec > 59 ||
+		    alrm->time.tm_hour > 23 || alrm->time.tm_min > 59) {
+			return -EINVAL;
+		}
+	}
+
+	spin_lock_irqsave(&rtc_lock, lock_flags);
+
+	ret = rtc_update_alarm(dev, &alrm->time);
+	if (ret)
+		goto out;
+
+	lp_cr = readl(ioaddr + SNVS_LPCR);
+
+	if (alrm->enabled)
+		lp_cr |= (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
+	else
+		lp_cr &= ~(SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
+
+	if (lp_cr & SNVS_LPCR_ALL_INT_EN) {
+		if (!pdata->irq_enable) {
+			enable_irq(pdata->irq);
+			pdata->irq_enable = true;
+		}
+	} else {
+		if (pdata->irq_enable) {
+			disable_irq(pdata->irq);
+			pdata->irq_enable = false;
+		}
+	}
+
+	writel(lp_cr, ioaddr + SNVS_LPCR);
+
+out:
+	rtc_write_sync_lp(ioaddr);
+	spin_unlock_irqrestore(&rtc_lock, lock_flags);
+
+	return ret;
+}
+
+/*!
+ * This function is used to provide the content for the /proc/driver/rtc
+ * file.
+ *
+ * @param  seq  buffer to hold the information that the driver wants to write
+ *
+ * @return  The number of bytes written into the rtc file.
+ */
+static int snvs_rtc_proc(struct device *dev, struct seq_file *seq)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+
+	seq_printf(seq, "alarm_IRQ\t: %s\n",
+		   (((readl(ioaddr + SNVS_LPCR)) & SNVS_LPCR_LPTA_EN) !=
+		    0) ? "yes" : "no");
+
+	return 0;
+}
+
+static int snvs_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	u32 lp_cr;
+	unsigned long lock_flags = 0;
+
+	spin_lock_irqsave(&rtc_lock, lock_flags);
+
+	if (enable) {
+		if (!pdata->irq_enable) {
+			enable_irq(pdata->irq);
+			pdata->irq_enable = true;
+		}
+		lp_cr = readl(ioaddr + SNVS_LPCR);
+		lp_cr |= (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
+		writel(lp_cr, ioaddr + SNVS_LPCR);
+	} else {
+		lp_cr = readl(ioaddr + SNVS_LPCR);
+		lp_cr &= ~(SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
+		if (((lp_cr & SNVS_LPCR_ALL_INT_EN) == 0)
+		    && (pdata->irq_enable)) {
+			disable_irq(pdata->irq);
+			pdata->irq_enable = false;
+		}
+		writel(lp_cr, ioaddr + SNVS_LPCR);
+	}
+
+	rtc_write_sync_lp(ioaddr);
+	spin_unlock_irqrestore(&rtc_lock, lock_flags);
+
+	return 0;
+}
+
+/*!
+ * This function is used to support some ioctl calls directly.
+ * Other ioctl calls are supported indirectly through the
+ * arm/common/rtctime.c file.
+ *
+ * @param  cmd          ioctl command as defined in include/linux/rtc.h
+ * @param  arg          value for the ioctl command
+ *
+ * @return  0 if successful or negative value otherwise.
+ */
+static int snvs_rtc_ioctl(struct device *dev, unsigned int cmd,
+			 unsigned long arg)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	u64 time_47bit;
+	int retVal;
+
+	switch (cmd) {
+	case RTC_READ_TIME_47BIT:
+		time_47bit = (((u64) (readl(ioaddr + SNVS_LPSRTCMR) &
+			((0x1 << CNTR_TO_SECS_SH) - 1)) << 32) |
+			((u64) readl(ioaddr + SNVS_LPSRTCLR)));
+
+		if (arg && copy_to_user((u64 *) arg, &time_47bit, sizeof(u64)))
+			return -EFAULT;
+
+		return 0;
+
+	/* This IOCTL to be used by processes to be notified of time changes */
+	case RTC_WAIT_TIME_SET:
+		/* don't block without releasing mutex first */
+		mutex_unlock(&pdata->rtc->ops_lock);
+
+		/* sleep till awakened by SRTC driver when LPSCMR is changed */
+		wait_for_completion(&snvs_completion);
+
+		/* relock mutex because rtc_dev_ioctl will unlock again */
+		retVal = mutex_lock_interruptible(&pdata->rtc->ops_lock);
+
+		/* copy the new time difference = new time - previous time
+		 * to the user param. The difference is a signed value */
+		if (arg && copy_to_user((int64_t *) arg, &time_diff,
+			sizeof(int64_t)))
+			return -EFAULT;
+
+		return retVal;
+
+	}
+
+	return -ENOIOCTLCMD;
+}
+
+/*!
+ * The RTC driver structure
+ */
+static struct rtc_class_ops snvs_rtc_ops = {
+	.open = snvs_rtc_open,
+	.release = snvs_rtc_release,
+	.read_time = snvs_rtc_read_time,
+	.set_time = snvs_rtc_set_time,
+	.read_alarm = snvs_rtc_read_alarm,
+	.set_alarm = snvs_rtc_set_alarm,
+	.proc = snvs_rtc_proc,
+	.ioctl = snvs_rtc_ioctl,
+	.alarm_irq_enable = snvs_rtc_alarm_irq_enable,
+};
+
+/*! SNVS RTC Power management control */
+static int __devinit snvs_rtc_probe(struct platform_device *pdev)
+{
+	struct timespec tv;
+	struct resource *res;
+	struct rtc_device *rtc;
+	struct rtc_drv_data *pdata = NULL;
+	void __iomem *ioaddr;
+	u32 lp_cr;
+	int ret = 0;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	ioaddr = ioremap(res->start, resource_size(res));
+	if (!ioaddr)
+		return -EADDRNOTAVAIL;
+
+	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return -ENOMEM;
+
+	pdata->ioaddr = ioaddr;
+
+	/* Configure and enable the RTC */
+	pdata->irq = platform_get_irq(pdev, 0);
+	if (pdata->irq >= 0) {
+		if (request_irq(pdata->irq, snvs_rtc_interrupt, IRQF_SHARED,
+				pdev->name, pdev) < 0) {
+			dev_warn(&pdev->dev, "interrupt not available.\n");
+			pdata->irq = -1;
+		} else {
+			disable_irq(pdata->irq);
+			pdata->irq_enable = false;
+		}
+	}
+
+	/* initialize glitch detect */
+	writel(SNVS_LPPGDR_INIT, ioaddr + SNVS_LPPGDR);
+	udelay(100);
+
+	/* clear lp interrupt status */
+	writel(0xFFFFFFFF, ioaddr + SNVS_LPSR);
+
+	/* Enable RTC */
+	lp_cr = readl(ioaddr + SNVS_LPCR);
+	if ((lp_cr & SNVS_LPCR_SRTC_ENV) == 0)
+		writel(lp_cr | SNVS_LPCR_SRTC_ENV, ioaddr + SNVS_LPCR);
+
+	udelay(100);
+
+	writel(0xFFFFFFFF, ioaddr + SNVS_LPSR);
+	udelay(100);
+
+	platform_set_drvdata(pdev, pdata);
+
+	rtc = rtc_device_register(pdev->name, &pdev->dev,
+				  &snvs_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc)) {
+		ret = PTR_ERR(rtc);
+		goto err_out;
+	}
+
+	pdata->rtc = rtc;
+
+	tv.tv_nsec = 0;
+	tv.tv_sec = rtc_read_lp_counter(ioaddr + SNVS_LPSRTCMR);
+
+	/* By default, devices should wakeup if they can */
+	/* So snvs is set as "should wakeup" as it can */
+	device_init_wakeup(&pdev->dev, 1);
+
+	return ret;
+
+err_out:
+	iounmap(ioaddr);
+	if (pdata->irq >= 0)
+		free_irq(pdata->irq, pdev);
+
+	return ret;
+}
+
+static int __devexit snvs_rtc_remove(struct platform_device *pdev)
+{
+	struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
+	rtc_device_unregister(pdata->rtc);
+	if (pdata->irq >= 0)
+		free_irq(pdata->irq, pdev);
+	iounmap(pdata->ioaddr);
+
+	return 0;
+}
+
+/*!
+ * This function is called to save the system time delta relative to
+ * the SNVS RTC when enterring a low power state. This time delta is
+ * then used on resume to adjust the system time to account for time
+ * loss while suspended.
+ *
+ * @param   pdev  not used
+ * @param   state Power state to enter.
+ *
+ * @return  The function always returns 0.
+ */
+static int snvs_rtc_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
+
+	if (device_may_wakeup(&pdev->dev)) {
+		enable_irq_wake(pdata->irq);
+	} else {
+		if (pdata->irq_enable)
+			disable_irq(pdata->irq);
+	}
+
+	return 0;
+}
+
+/*!
+ * This function is called to correct the system time based on the
+ * current SNVS RTC time relative to the time delta saved during
+ * suspend.
+ *
+ * @param   pdev  not used
+ *
+ * @return  The function always returns 0.
+ */
+static int snvs_rtc_resume(struct platform_device *pdev)
+{
+	struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
+
+	if (device_may_wakeup(&pdev->dev)) {
+		disable_irq_wake(pdata->irq);
+	} else {
+		if (pdata->irq_enable)
+			enable_irq(pdata->irq);
+	}
+
+	return 0;
+}
+
+static const struct of_device_id __devinitdata snvs_dt_ids[] = {
+	{ .compatible = "fsl,snvs" },
+	{ /* sentinel */ }
+};
+
+/*!
+ * Contains pointers to the power management callback functions.
+ */
+static struct platform_driver snvs_rtc_driver = {
+	.driver = {
+		.name	= "snvs_rtc",
+		.owner	= THIS_MODULE,
+		.of_match_table = snvs_dt_ids,
+	},
+	.probe = snvs_rtc_probe,
+	.remove = __exit_p(snvs_rtc_remove),
+	.suspend = snvs_rtc_suspend,
+	.resume = snvs_rtc_resume,
+};
+
+/*!
+ * This function creates the /proc/driver/rtc file and registers the device RTC
+ * in the /dev/misc directory. It also reads the RTC value from external source
+ * and setup the internal RTC properly.
+ *
+ * @return  -1 if RTC is failed to initialize; 0 is successful.
+ */
+static int __init snvs_rtc_init(void)
+{
+	return platform_driver_register(&snvs_rtc_driver);
+}
+module_init(snvs_rtc_init);
+
+/*!
+ * This function removes the /proc/driver/rtc file and un-registers the
+ * device RTC from the /dev/misc directory.
+ */
+static void __exit snvs_rtc_exit(void)
+{
+	platform_driver_unregister(&snvs_rtc_driver);
+}
+module_exit(snvs_rtc_exit);
+
+MODULE_AUTHOR("Anish Trivedi <anish at freescale.com>, "
+	      "Eric Miao <eric.miao at linaro.org>, "
+	      "Anson Huang <b20788 at freescale.com>, "
+	      "Ying-Chun Liu (PaulLiu) <paul.liu at linaro.org>");
+MODULE_DESCRIPTION("SNVS Realtime Clock Driver (RTC)");
+MODULE_LICENSE("GPL v2");
-- 
1.7.9.1




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