Message-ID: <20171128073927.12035-1-linux-kernel-dev@beckhoff.com>
Date:   Tue, 28 Nov 2017 08:39:27 +0100
From:   <linux-kernel-dev@...khoff.com>
To:     Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...e-electrons.com>
CC:     Patrick Bruenn <p.bruenn@...khoff.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "open list:REAL TIME CLOCK (RTC) SUBSYSTEM" 
        <linux-rtc@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Fabio Estevam <fabio.estevam@....com>,
        Juergen Borleis <jbe@...gutronix.de>,
        Noel Vellemans <Noel.Vellemans@...ionbms.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>,
        Russell King <linux@...linux.org.uk>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: [PATCH] rtc: add mxc driver for i.MX53

From: Patrick Bruenn <p.bruenn@...khoff.com>

Neither rtc-imxdi nor rtc-mxc are compatible with i.MX53.
Add a modernized version of mxc_v2 from here:
http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/tree/drivers/rtc/rtc-mxc_v2.c?h=imx_2.6.35_11.09.01

Changes to that version:
- updated to v4.15-rc1
- removed ioctl()
- removed proc()
- removed manual(redundant) enable_irq flag

Signed-off-by: Patrick Bruenn <p.bruenn@...khoff.com>

---

Open issues:
- driver naming, should it be merged with rtc-mxc.c ?
- document DT binding "fsl,imx53-rtc" accordingly
- Should unused defines be removed or kept for someone else to be
  useful?
- Is the use of __raw_readl/writel() correct? Should it be replaced with
  readl/writel()?
- suspend/resume() seems different to existing rtc-mxc.c, should I apply
  the pattern from rtc-mxc.c?
- On Shawns tree imx53.dtsi has been reverted already[1][2]. Should I split
  the imx53.dtsi change into a separate patch based on his tree? Or can
  we still stop the full revert and just remove the imx25-rtc compatible?
  I am not in a hurry, so we could just wait until the revert landed in
  Linus tree. Whatever you think is best.

[1] https://www.spinics.net/lists/arm-kernel/msg617113.html
[2] commit ee76f7729babd2700afd6f3874449d8084dd85ea

To: Alessandro Zummo <a.zummo@...ertech.it>
To: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: Mark Rutland <mark.rutland@....com> (maintainer:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS)
Cc: linux-rtc@...r.kernel.org (open list:REAL TIME CLOCK (RTC) SUBSYSTEM)
Cc: devicetree@...r.kernel.org (open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS)
Cc: linux-kernel@...r.kernel.org (open list)
Cc: Fabio Estevam <fabio.estevam@....com>
Cc: Juergen Borleis <jbe@...gutronix.de>
Cc: Noel Vellemans <Noel.Vellemans@...ionbms.com>
Cc: Shawn Guo <shawnguo@...nel.org>
Cc: Sascha Hauer <kernel@...gutronix.de> (maintainer:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE)
Cc: Russell King <linux@...linux.org.uk> (maintainer:ARM PORT)
Cc: linux-arm-kernel@...ts.infradead.org (moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE)
---
 arch/arm/boot/dts/imx53.dtsi |   2 +-
 drivers/rtc/Makefile         |   1 +
 drivers/rtc/rtc-mxc_v2.c     | 531 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 533 insertions(+), 1 deletion(-)
 create mode 100644 drivers/rtc/rtc-mxc_v2.c

diff --git a/arch/arm/boot/dts/imx53.dtsi b/arch/arm/boot/dts/imx53.dtsi
index 589a67c5f796..3d1a55e11ea8 100644
--- a/arch/arm/boot/dts/imx53.dtsi
+++ b/arch/arm/boot/dts/imx53.dtsi
@@ -434,7 +434,7 @@
 			};
 
 			srtc: srtc@...a4000 {
-				compatible = "fsl,imx53-rtc", "fsl,imx25-rtc";
+				compatible = "fsl,imx53-rtc";
 				reg = <0x53fa4000 0x4000>;
 				interrupts = <24>;
 				interrupt-parent = <&tzic>;
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index f2f50c11dc38..fb3dc458c185 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -106,6 +106,7 @@ obj-$(CONFIG_RTC_DRV_MT6397)	+= rtc-mt6397.o
 obj-$(CONFIG_RTC_DRV_MT7622)	+= rtc-mt7622.o
 obj-$(CONFIG_RTC_DRV_MV)	+= rtc-mv.o
 obj-$(CONFIG_RTC_DRV_MXC)	+= rtc-mxc.o
+obj-$(CONFIG_RTC_DRV_MXC)	+= rtc-mxc_v2.o
 obj-$(CONFIG_RTC_DRV_NUC900)	+= rtc-nuc900.o
 obj-$(CONFIG_RTC_DRV_OMAP)	+= rtc-omap.o
 obj-$(CONFIG_RTC_DRV_OPAL)	+= rtc-opal.o
diff --git a/drivers/rtc/rtc-mxc_v2.c b/drivers/rtc/rtc-mxc_v2.c
new file mode 100644
index 000000000000..5049b521b38e
--- /dev/null
+++ b/drivers/rtc/rtc-mxc_v2.c
@@ -0,0 +1,531 @@
+/*
+ * Copyright (C) 2004-2011 Freescale Semiconductor, Inc. All Rights Reserved.
+ */
+
+/*
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ */
+/*
+ * Implementation based on rtc-ds1553.c
+ */
+
+/*!
+ * @defgroup RTC Real Time Clock (RTC) Driver for i.MX53
+ */
+/*!
+ * @file rtc-mxc_v2.c
+ * @brief Real Time Clock interface
+ *
+ * This file contains Real Time Clock interface for Linux.
+ *
+ * @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/clk.h>
+#include <linux/device.h>
+#include <linux/uaccess.h>
+#include <linux/io.h>
+//#include <linux/mxc_srtc.h>
+#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)
+
+#define SRTC_LPSCLR_LLPSC_LSH	17	/* start bit for LSB time value */
+
+#define SRTC_LPPDR_INIT       0x41736166	/* init for glitch detect */
+
+#define SRTC_LPCR_SWR_LP      (1 << 0)	/* lp software reset */
+#define SRTC_LPCR_EN_LP       (1 << 3)	/* lp enable */
+#define SRTC_LPCR_WAE         (1 << 4)	/* lp wakeup alarm enable */
+#define SRTC_LPCR_SAE         (1 << 5)	/* lp security alarm enable */
+#define SRTC_LPCR_SI          (1 << 6)	/* lp security interrupt enable */
+#define SRTC_LPCR_ALP         (1 << 7)	/* lp alarm flag */
+#define SRTC_LPCR_LTC         (1 << 8)	/* lp lock time counter */
+#define SRTC_LPCR_LMC         (1 << 9)	/* lp lock monotonic counter */
+#define SRTC_LPCR_SV          (1 << 10)	/* lp security violation */
+#define SRTC_LPCR_NSA         (1 << 11)	/* lp non secure access */
+#define SRTC_LPCR_NVEIE       (1 << 12)	/* lp non valid state exit int en */
+#define SRTC_LPCR_IEIE        (1 << 13)	/* lp init state exit int enable */
+#define SRTC_LPCR_NVE         (1 << 14)	/* lp non valid state exit bit */
+#define SRTC_LPCR_IE          (1 << 15)	/* lp init state exit bit */
+
+#define SRTC_LPCR_ALL_INT_EN (SRTC_LPCR_WAE | SRTC_LPCR_SAE | \
+			      SRTC_LPCR_SI | SRTC_LPCR_ALP | \
+			      SRTC_LPCR_NVEIE | SRTC_LPCR_IEIE)
+
+#define SRTC_LPSR_TRI         (1 << 0)	/* lp time read invalidate */
+#define SRTC_LPSR_PGD         (1 << 1)	/* lp power supply glitc detected */
+#define SRTC_LPSR_CTD         (1 << 2)	/* lp clock tampering detected */
+#define SRTC_LPSR_ALP         (1 << 3)	/* lp alarm flag */
+#define SRTC_LPSR_MR          (1 << 4)	/* lp monotonic counter rollover */
+#define SRTC_LPSR_TR          (1 << 5)	/* lp time rollover */
+#define SRTC_LPSR_EAD         (1 << 6)	/* lp external alarm detected */
+#define SRTC_LPSR_IT0         (1 << 7)	/* lp IIM throttle */
+#define SRTC_LPSR_IT1         (1 << 8)
+#define SRTC_LPSR_IT2         (1 << 9)
+#define SRTC_LPSR_SM0         (1 << 10)	/* lp security mode */
+#define SRTC_LPSR_SM1         (1 << 11)
+#define SRTC_LPSR_STATE_LP0   (1 << 12)	/* lp state */
+#define SRTC_LPSR_STATE_LP1   (1 << 13)
+#define SRTC_LPSR_NVES        (1 << 14)	/* lp non-valid state exit status */
+#define SRTC_LPSR_IES         (1 << 15)	/* lp init state exit status */
+
+#define MAX_PIE_NUM     15
+#define MAX_PIE_FREQ    32768
+#define MIN_PIE_FREQ	1
+
+#define SRTC_PI0         (1 << 0)
+#define SRTC_PI1         (1 << 1)
+#define SRTC_PI2         (1 << 2)
+#define SRTC_PI3         (1 << 3)
+#define SRTC_PI4         (1 << 4)
+#define SRTC_PI5         (1 << 5)
+#define SRTC_PI6         (1 << 6)
+#define SRTC_PI7         (1 << 7)
+#define SRTC_PI8         (1 << 8)
+#define SRTC_PI9         (1 << 9)
+#define SRTC_PI10        (1 << 10)
+#define SRTC_PI11        (1 << 11)
+#define SRTC_PI12        (1 << 12)
+#define SRTC_PI13        (1 << 13)
+#define SRTC_PI14        (1 << 14)
+#define SRTC_PI15        (1 << 15)
+
+#define PIT_ALL_ON      (SRTC_PI1 | SRTC_PI2 | SRTC_PI3 | \
+			SRTC_PI4 | SRTC_PI5 | SRTC_PI6 | SRTC_PI7 | \
+			SRTC_PI8 | SRTC_PI9 | SRTC_PI10 | SRTC_PI11 | \
+			SRTC_PI12 | SRTC_PI13 | SRTC_PI14 | SRTC_PI15)
+
+#define SRTC_SWR_HP      (1 << 0)	/* hp software reset */
+#define SRTC_EN_HP       (1 << 3)	/* hp enable */
+#define SRTC_TS          (1 << 4)	/* time synchronize hp with lp */
+
+#define SRTC_IE_AHP      (1 << 16)	/* Alarm HP Interrupt Enable bit */
+#define SRTC_IE_WDHP     (1 << 18)	/* Write Done HP Interrupt Enable bit */
+#define SRTC_IE_WDLP     (1 << 19)	/* Write Done LP Interrupt Enable bit */
+
+#define SRTC_ISR_AHP     (1 << 16)	/* interrupt status: alarm hp */
+#define SRTC_ISR_WDHP    (1 << 18)	/* interrupt status: write done hp */
+#define SRTC_ISR_WDLP    (1 << 19)	/* interrupt status: write done lp */
+#define SRTC_ISR_WPHP    (1 << 20)	/* interrupt status: write pending hp */
+#define SRTC_ISR_WPLP    (1 << 21)	/* interrupt status: write pending lp */
+
+#define SRTC_LPSCMR	0x00	/* LP Secure Counter MSB Reg */
+#define SRTC_LPSCLR	0x04	/* LP Secure Counter LSB Reg */
+#define SRTC_LPSAR	0x08	/* LP Secure Alarm Reg */
+#define SRTC_LPSMCR	0x0C	/* LP Secure Monotonic Counter Reg */
+#define SRTC_LPCR	0x10	/* LP Control Reg */
+#define SRTC_LPSR	0x14	/* LP Status Reg */
+#define SRTC_LPPDR	0x18	/* LP Power Supply Glitch Detector Reg */
+#define SRTC_LPGR	0x1C	/* LP General Purpose Reg */
+#define SRTC_HPCMR	0x20	/* HP Counter MSB Reg */
+#define SRTC_HPCLR	0x24	/* HP Counter LSB Reg */
+#define SRTC_HPAMR	0x28	/* HP Alarm MSB Reg */
+#define SRTC_HPALR	0x2C	/* HP Alarm LSB Reg */
+#define SRTC_HPCR	0x30	/* HP Control Reg */
+#define SRTC_HPISR	0x34	/* HP Interrupt Status Reg */
+#define SRTC_HPIENR	0x38	/* HP Interrupt Enable Reg */
+
+#define SRTC_SECMODE_MASK	0x3	/* the mask of SRTC security mode */
+#define SRTC_SECMODE_LOW	0x0	/* Low Security */
+#define SRTC_SECMODE_MED	0x1	/* Medium Security */
+#define SRTC_SECMODE_HIGH	0x2	/* High Security */
+#define SRTC_SECMODE_RESERVED	0x3	/* Reserved */
+
+struct rtc_drv_data {
+	struct rtc_device *rtc;
+	void __iomem *ioaddr;
+	int irq;
+	struct clk *clk;
+};
+
+static DEFINE_SPINLOCK(rtc_lock);
+
+/*!
+ * 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, count;
+	/* Wait for 3 CKIL cycles */
+	for (i = 0; i < 3; i++) {
+		count = readl(ioaddr + SRTC_LPSCLR);
+		while ((readl(ioaddr + SRTC_LPSCLR)) == count)
+			;
+	}
+}
+
+/*!
+ * 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;
+	int ret;
+
+	now = __raw_readl(ioaddr + SRTC_LPSCMR);
+	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);
+
+	__raw_writel(time, ioaddr + SRTC_LPSAR);
+
+	/* clear alarm interrupt status bit */
+	__raw_writel(SRTC_LPSR_ALP, ioaddr + SRTC_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 mxc_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 = __raw_readl(ioaddr + SRTC_LPSR);
+	lp_cr = __raw_readl(ioaddr + SRTC_LPCR);
+
+	/* update irq data & counter */
+	if (lp_status & SRTC_LPSR_ALP) {
+		if (lp_cr & SRTC_LPCR_ALP)
+			events |= (RTC_AF | RTC_IRQF);
+
+		/* disable further lp alarm interrupts */
+		lp_cr &= ~(SRTC_LPCR_ALP | SRTC_LPCR_WAE);
+	}
+
+	/* Update interrupt enables */
+	__raw_writel(lp_cr, ioaddr + SRTC_LPCR);
+
+	/* clear interrupt status */
+	__raw_writel(lp_status, ioaddr + SRTC_LPSR);
+
+	rtc_write_sync_lp(ioaddr);
+	rtc_update_irq(pdata->rtc, 1, events);
+	return IRQ_HANDLED;
+}
+
+/*!
+ * 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 mxc_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	time_t now = readl(pdata->ioaddr + SRTC_LPSCMR);
+
+	rtc_time_to_tm(now, tm);
+	return rtc_valid_tm(tm);
+}
+
+/*!
+ * 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 mxc_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	time64_t time = rtc_tm_to_time64(tm);
+
+	if (time > UINT_MAX) {
+		dev_warn(dev, "time_t has overflow\n");
+	}
+
+	writel(time, pdata->ioaddr + SRTC_LPSCMR);
+	rtc_write_sync_lp(pdata->ioaddr);
+	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 mxc_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(__raw_readl(ioaddr + SRTC_LPSAR), &alrm->time);
+	alrm->pending =
+	    ((__raw_readl(ioaddr + SRTC_LPSR) & SRTC_LPSR_ALP) != 0) ? 1 : 0;
+
+	return 0;
+}
+
+static int mxc_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	unsigned long lock_flags = 0;
+	u32 lp_cr;
+
+	spin_lock_irqsave(&rtc_lock, lock_flags);
+	lp_cr = __raw_readl(pdata->ioaddr + SRTC_LPCR);
+
+	if (enable)
+		lp_cr |= (SRTC_LPCR_ALP | SRTC_LPCR_WAE);
+	else
+		lp_cr &= ~(SRTC_LPCR_ALP | SRTC_LPCR_WAE);
+
+	__raw_writel(lp_cr, pdata->ioaddr + SRTC_LPCR);
+	spin_unlock_irqrestore(&rtc_lock, lock_flags);
+	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 mxc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	int ret;
+
+	ret = rtc_update_alarm(dev, &alrm->time);
+	if (!ret)
+		mxc_rtc_alarm_irq_enable(dev, alrm->enabled);
+
+	rtc_write_sync_lp(ioaddr);
+	return ret;
+}
+
+/*!
+ * The RTC driver structure
+ */
+static const struct rtc_class_ops mxc_rtc_ops = {
+	.read_time = mxc_rtc_read_time,
+	.set_time = mxc_rtc_set_time,
+	.read_alarm = mxc_rtc_read_alarm,
+	.set_alarm = mxc_rtc_set_alarm,
+	.alarm_irq_enable = mxc_rtc_alarm_irq_enable,
+};
+
+/*! MXC RTC Power management control */
+static int mxc_rtc_probe(struct platform_device *pdev)
+{
+	struct timespec tv;
+	struct resource *res;
+	struct rtc_drv_data *pdata = NULL;
+	void __iomem *ioaddr;
+	int ret = 0;
+
+	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	pdata->ioaddr = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(pdata->ioaddr))
+		return PTR_ERR(pdata->ioaddr);
+
+	ioaddr = pdata->ioaddr;
+
+	pdata->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(pdata->clk)) {
+		dev_err(&pdev->dev, "unable to get rtc clock!\n");
+		return PTR_ERR(pdata->clk);
+	}
+	ret = clk_prepare_enable(pdata->clk);
+	if (ret)
+		return ret;
+
+	/* Configure and enable the RTC */
+	pdata->irq = platform_get_irq(pdev, 0);
+	if (pdata->irq >= 0
+	    && devm_request_irq(&pdev->dev, pdata->irq, mxc_rtc_interrupt,
+				IRQF_SHARED, pdev->name, pdev) < 0) {
+		dev_warn(&pdev->dev, "interrupt not available.\n");
+		pdata->irq = -1;
+	}
+
+	if (pdata->irq >= 0)
+		device_init_wakeup(&pdev->dev, 1);
+
+	/* initialize glitch detect */
+	__raw_writel(SRTC_LPPDR_INIT, ioaddr + SRTC_LPPDR);
+	udelay(100);
+
+	/* clear lp interrupt status */
+	__raw_writel(0xFFFFFFFF, ioaddr + SRTC_LPSR);
+	udelay(100);
+
+	/* move out of init state */
+	__raw_writel((SRTC_LPCR_IE | SRTC_LPCR_NSA), ioaddr + SRTC_LPCR);
+
+	udelay(100);
+
+	while ((__raw_readl(ioaddr + SRTC_LPSR) & SRTC_LPSR_IES) == 0)
+		;
+
+	/* move out of non-valid state */
+	__raw_writel((SRTC_LPCR_IE | SRTC_LPCR_NVE | SRTC_LPCR_NSA |
+		      SRTC_LPCR_EN_LP), ioaddr + SRTC_LPCR);
+
+	udelay(100);
+
+	while ((__raw_readl(ioaddr + SRTC_LPSR) & SRTC_LPSR_NVES) == 0)
+		;
+
+	__raw_writel(0xFFFFFFFF, ioaddr + SRTC_LPSR);
+	udelay(100);
+
+	platform_set_drvdata(pdev, pdata);
+	pdata->rtc =
+	    devm_rtc_device_register(&pdev->dev, pdev->name, &mxc_rtc_ops,
+				     THIS_MODULE);
+	if (IS_ERR(pdata->rtc)) {
+		ret = PTR_ERR(pdata->rtc);
+		goto exit_put_clk;
+	}
+
+	tv.tv_nsec = 0;
+	tv.tv_sec = __raw_readl(ioaddr + SRTC_LPSCMR);
+
+	/* By default, devices should wakeup if they can */
+	/* So srtc is set as "should wakeup" as it can */
+	device_init_wakeup(&pdev->dev, 1);
+
+	return ret;
+
+exit_put_clk:
+	clk_disable_unprepare(pdata->clk);
+	return ret;
+}
+
+static int __exit mxc_rtc_remove(struct platform_device *pdev)
+{
+	struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
+
+	clk_disable_unprepare(pdata->clk);
+	return 0;
+}
+
+/*!
+ * This function is called to save the system time delta relative to
+ * the MXC 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 mxc_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);
+
+	return 0;
+}
+
+/*!
+ * This function is called to correct the system time based on the
+ * current MXC RTC time relative to the time delta saved during
+ * suspend.
+ *
+ * @param   pdev  not used
+ *
+ * @return  The function always returns 0.
+ */
+static int mxc_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);
+
+	return 0;
+}
+
+static const struct of_device_id mxc_ids[] = {
+	{.compatible = "fsl,imx53-rtc",},
+	{}
+};
+
+/*!
+ * Contains pointers to the power management callback functions.
+ */
+static struct platform_driver mxc_rtc_driver = {
+	.driver = {
+		   .name = "mxc_rtc_v8",
+		   .of_match_table = mxc_ids,
+		   },
+	.probe = mxc_rtc_probe,
+	.remove = mxc_rtc_remove,
+	.suspend = mxc_rtc_suspend,
+	.resume = mxc_rtc_resume,
+};
+
+module_platform_driver(mxc_rtc_driver);
+
+MODULE_AUTHOR("Freescale Semiconductor, Inc.");
+MODULE_DESCRIPTION("Realtime Clock Driver (RTC)");
+MODULE_LICENSE("GPL");
-- 
2.11.0

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