Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 883 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-imxdi.c b/drivers/rtc/rtc-imxdi.c
new file mode 100644
index 000000000..80931114c
--- /dev/null
+++ b/drivers/rtc/rtc-imxdi.c
@@ -0,0 +1,883 @@
+/*
+ * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Copyright 2010 Orex Computed Radiography
+ */
+
+/*
+ * 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
+ */
+
+/* based on rtc-mc13892.c */
+
+/*
+ * This driver uses the 47-bit 32 kHz counter in the Freescale DryIce block
+ * to implement a Linux RTC. Times and alarms are truncated to seconds.
+ * Since the RTC framework performs API locking via rtc->ops_lock the
+ * only simultaneous accesses we need to deal with is updating DryIce
+ * registers while servicing an alarm.
+ *
+ * Note that reading the DSR (DryIce Status Register) automatically clears
+ * the WCF (Write Complete Flag). All DryIce writes are synchronized to the
+ * LP (Low Power) domain and set the WCF upon completion. Writes to the
+ * DIER (DryIce Interrupt Enable Register) are the only exception. These
+ * occur at normal bus speeds and do not set WCF.  Periodic interrupts are
+ * not supported by the hardware.
+ */
+
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/workqueue.h>
+#include <linux/of.h>
+
+/* DryIce Register Definitions */
+
+#define DTCMR     0x00           /* Time Counter MSB Reg */
+#define DTCLR     0x04           /* Time Counter LSB Reg */
+
+#define DCAMR     0x08           /* Clock Alarm MSB Reg */
+#define DCALR     0x0c           /* Clock Alarm LSB Reg */
+#define DCAMR_UNSET  0xFFFFFFFF  /* doomsday - 1 sec */
+
+#define DCR       0x10           /* Control Reg */
+#define DCR_TDCHL (1 << 30)      /* Tamper-detect configuration hard lock */
+#define DCR_TDCSL (1 << 29)      /* Tamper-detect configuration soft lock */
+#define DCR_KSSL  (1 << 27)      /* Key-select soft lock */
+#define DCR_MCHL  (1 << 20)      /* Monotonic-counter hard lock */
+#define DCR_MCSL  (1 << 19)      /* Monotonic-counter soft lock */
+#define DCR_TCHL  (1 << 18)      /* Timer-counter hard lock */
+#define DCR_TCSL  (1 << 17)      /* Timer-counter soft lock */
+#define DCR_FSHL  (1 << 16)      /* Failure state hard lock */
+#define DCR_TCE   (1 << 3)       /* Time Counter Enable */
+#define DCR_MCE   (1 << 2)       /* Monotonic Counter Enable */
+
+#define DSR       0x14           /* Status Reg */
+#define DSR_WTD   (1 << 23)      /* Wire-mesh tamper detected */
+#define DSR_ETBD  (1 << 22)      /* External tamper B detected */
+#define DSR_ETAD  (1 << 21)      /* External tamper A detected */
+#define DSR_EBD   (1 << 20)      /* External boot detected */
+#define DSR_SAD   (1 << 19)      /* SCC alarm detected */
+#define DSR_TTD   (1 << 18)      /* Temperature tamper detected */
+#define DSR_CTD   (1 << 17)      /* Clock tamper detected */
+#define DSR_VTD   (1 << 16)      /* Voltage tamper detected */
+#define DSR_WBF   (1 << 10)      /* Write Busy Flag (synchronous) */
+#define DSR_WNF   (1 << 9)       /* Write Next Flag (synchronous) */
+#define DSR_WCF   (1 << 8)       /* Write Complete Flag (synchronous)*/
+#define DSR_WEF   (1 << 7)       /* Write Error Flag */
+#define DSR_CAF   (1 << 4)       /* Clock Alarm Flag */
+#define DSR_MCO   (1 << 3)       /* monotonic counter overflow */
+#define DSR_TCO   (1 << 2)       /* time counter overflow */
+#define DSR_NVF   (1 << 1)       /* Non-Valid Flag */
+#define DSR_SVF   (1 << 0)       /* Security Violation Flag */
+
+#define DIER      0x18           /* Interrupt Enable Reg (synchronous) */
+#define DIER_WNIE (1 << 9)       /* Write Next Interrupt Enable */
+#define DIER_WCIE (1 << 8)       /* Write Complete Interrupt Enable */
+#define DIER_WEIE (1 << 7)       /* Write Error Interrupt Enable */
+#define DIER_CAIE (1 << 4)       /* Clock Alarm Interrupt Enable */
+#define DIER_SVIE (1 << 0)       /* Security-violation Interrupt Enable */
+
+#define DMCR      0x1c           /* DryIce Monotonic Counter Reg */
+
+#define DTCR      0x28           /* DryIce Tamper Configuration Reg */
+#define DTCR_MOE  (1 << 9)       /* monotonic overflow enabled */
+#define DTCR_TOE  (1 << 8)       /* time overflow enabled */
+#define DTCR_WTE  (1 << 7)       /* wire-mesh tamper enabled */
+#define DTCR_ETBE (1 << 6)       /* external B tamper enabled */
+#define DTCR_ETAE (1 << 5)       /* external A tamper enabled */
+#define DTCR_EBE  (1 << 4)       /* external boot tamper enabled */
+#define DTCR_SAIE (1 << 3)       /* SCC enabled */
+#define DTCR_TTE  (1 << 2)       /* temperature tamper enabled */
+#define DTCR_CTE  (1 << 1)       /* clock tamper enabled */
+#define DTCR_VTE  (1 << 0)       /* voltage tamper enabled */
+
+#define DGPR      0x3c           /* DryIce General Purpose Reg */
+
+/**
+ * struct imxdi_dev - private imxdi rtc data
+ * @pdev: pionter to platform dev
+ * @rtc: pointer to rtc struct
+ * @ioaddr: IO registers pointer
+ * @clk: input reference clock
+ * @dsr: copy of the DSR register
+ * @irq_lock: interrupt enable register (DIER) lock
+ * @write_wait: registers write complete queue
+ * @write_mutex: serialize registers write
+ * @work: schedule alarm work
+ */
+struct imxdi_dev {
+	struct platform_device *pdev;
+	struct rtc_device *rtc;
+	void __iomem *ioaddr;
+	struct clk *clk;
+	u32 dsr;
+	spinlock_t irq_lock;
+	wait_queue_head_t write_wait;
+	struct mutex write_mutex;
+	struct work_struct work;
+};
+
+/* Some background:
+ *
+ * The DryIce unit is a complex security/tamper monitor device. To be able do
+ * its job in a useful manner it runs a bigger statemachine to bring it into
+ * security/tamper failure state and once again to bring it out of this state.
+ *
+ * This unit can be in one of three states:
+ *
+ * - "NON-VALID STATE"
+ *   always after the battery power was removed
+ * - "FAILURE STATE"
+ *   if one of the enabled security events has happened
+ * - "VALID STATE"
+ *   if the unit works as expected
+ *
+ * Everything stops when the unit enters the failure state including the RTC
+ * counter (to be able to detect the time the security event happened).
+ *
+ * The following events (when enabled) let the DryIce unit enter the failure
+ * state:
+ *
+ * - wire-mesh-tamper detect
+ * - external tamper B detect
+ * - external tamper A detect
+ * - temperature tamper detect
+ * - clock tamper detect
+ * - voltage tamper detect
+ * - RTC counter overflow
+ * - monotonic counter overflow
+ * - external boot
+ *
+ * If we find the DryIce unit in "FAILURE STATE" and the TDCHL cleared, we
+ * can only detect this state. In this case the unit is completely locked and
+ * must force a second "SYSTEM POR" to bring the DryIce into the
+ * "NON-VALID STATE" + "FAILURE STATE" where a recovery is possible.
+ * If the TDCHL is set in the "FAILURE STATE" we are out of luck. In this case
+ * a battery power cycle is required.
+ *
+ * In the "NON-VALID STATE" + "FAILURE STATE" we can clear the "FAILURE STATE"
+ * and recover the DryIce unit. By clearing the "NON-VALID STATE" as the last
+ * task, we bring back this unit into life.
+ */
+
+/*
+ * Do a write into the unit without interrupt support.
+ * We do not need to check the WEF here, because the only reason this kind of
+ * write error can happen is if we write to the unit twice within the 122 us
+ * interval. This cannot happen, since we are using this function only while
+ * setting up the unit.
+ */
+static void di_write_busy_wait(const struct imxdi_dev *imxdi, u32 val,
+			       unsigned reg)
+{
+	/* do the register write */
+	writel(val, imxdi->ioaddr + reg);
+
+	/*
+	 * now it takes four 32,768 kHz clock cycles to take
+	 * the change into effect = 122 us
+	 */
+	usleep_range(130, 200);
+}
+
+static void di_report_tamper_info(struct imxdi_dev *imxdi,  u32 dsr)
+{
+	u32 dtcr;
+
+	dtcr = readl(imxdi->ioaddr + DTCR);
+
+	dev_emerg(&imxdi->pdev->dev, "DryIce tamper event detected\n");
+	/* the following flags force a transition into the "FAILURE STATE" */
+	if (dsr & DSR_VTD)
+		dev_emerg(&imxdi->pdev->dev, "%sVoltage Tamper Event\n",
+			  dtcr & DTCR_VTE ? "" : "Spurious ");
+
+	if (dsr & DSR_CTD)
+		dev_emerg(&imxdi->pdev->dev, "%s32768 Hz Clock Tamper Event\n",
+			  dtcr & DTCR_CTE ? "" : "Spurious ");
+
+	if (dsr & DSR_TTD)
+		dev_emerg(&imxdi->pdev->dev, "%sTemperature Tamper Event\n",
+			  dtcr & DTCR_TTE ? "" : "Spurious ");
+
+	if (dsr & DSR_SAD)
+		dev_emerg(&imxdi->pdev->dev,
+			  "%sSecure Controller Alarm Event\n",
+			  dtcr & DTCR_SAIE ? "" : "Spurious ");
+
+	if (dsr & DSR_EBD)
+		dev_emerg(&imxdi->pdev->dev, "%sExternal Boot Tamper Event\n",
+			  dtcr & DTCR_EBE ? "" : "Spurious ");
+
+	if (dsr & DSR_ETAD)
+		dev_emerg(&imxdi->pdev->dev, "%sExternal Tamper A Event\n",
+			  dtcr & DTCR_ETAE ? "" : "Spurious ");
+
+	if (dsr & DSR_ETBD)
+		dev_emerg(&imxdi->pdev->dev, "%sExternal Tamper B Event\n",
+			  dtcr & DTCR_ETBE ? "" : "Spurious ");
+
+	if (dsr & DSR_WTD)
+		dev_emerg(&imxdi->pdev->dev, "%sWire-mesh Tamper Event\n",
+			  dtcr & DTCR_WTE ? "" : "Spurious ");
+
+	if (dsr & DSR_MCO)
+		dev_emerg(&imxdi->pdev->dev,
+			  "%sMonotonic-counter Overflow Event\n",
+			  dtcr & DTCR_MOE ? "" : "Spurious ");
+
+	if (dsr & DSR_TCO)
+		dev_emerg(&imxdi->pdev->dev, "%sTimer-counter Overflow Event\n",
+			  dtcr & DTCR_TOE ? "" : "Spurious ");
+}
+
+static void di_what_is_to_be_done(struct imxdi_dev *imxdi,
+				  const char *power_supply)
+{
+	dev_emerg(&imxdi->pdev->dev, "Please cycle the %s power supply in order to get the DryIce/RTC unit working again\n",
+		  power_supply);
+}
+
+static int di_handle_failure_state(struct imxdi_dev *imxdi, u32 dsr)
+{
+	u32 dcr;
+
+	dev_dbg(&imxdi->pdev->dev, "DSR register reports: %08X\n", dsr);
+
+	/* report the cause */
+	di_report_tamper_info(imxdi, dsr);
+
+	dcr = readl(imxdi->ioaddr + DCR);
+
+	if (dcr & DCR_FSHL) {
+		/* we are out of luck */
+		di_what_is_to_be_done(imxdi, "battery");
+		return -ENODEV;
+	}
+	/*
+	 * with the next SYSTEM POR we will transit from the "FAILURE STATE"
+	 * into the "NON-VALID STATE" + "FAILURE STATE"
+	 */
+	di_what_is_to_be_done(imxdi, "main");
+
+	return -ENODEV;
+}
+
+static int di_handle_valid_state(struct imxdi_dev *imxdi, u32 dsr)
+{
+	/* initialize alarm */
+	di_write_busy_wait(imxdi, DCAMR_UNSET, DCAMR);
+	di_write_busy_wait(imxdi, 0, DCALR);
+
+	/* clear alarm flag */
+	if (dsr & DSR_CAF)
+		di_write_busy_wait(imxdi, DSR_CAF, DSR);
+
+	return 0;
+}
+
+static int di_handle_invalid_state(struct imxdi_dev *imxdi, u32 dsr)
+{
+	u32 dcr, sec;
+
+	/*
+	 * lets disable all sources which can force the DryIce unit into
+	 * the "FAILURE STATE" for now
+	 */
+	di_write_busy_wait(imxdi, 0x00000000, DTCR);
+	/* and lets protect them at runtime from any change */
+	di_write_busy_wait(imxdi, DCR_TDCSL, DCR);
+
+	sec = readl(imxdi->ioaddr + DTCMR);
+	if (sec != 0)
+		dev_warn(&imxdi->pdev->dev,
+			 "The security violation has happened at %u seconds\n",
+			 sec);
+	/*
+	 * the timer cannot be set/modified if
+	 * - the TCHL or TCSL bit is set in DCR
+	 */
+	dcr = readl(imxdi->ioaddr + DCR);
+	if (!(dcr & DCR_TCE)) {
+		if (dcr & DCR_TCHL) {
+			/* we are out of luck */
+			di_what_is_to_be_done(imxdi, "battery");
+			return -ENODEV;
+		}
+		if (dcr & DCR_TCSL) {
+			di_what_is_to_be_done(imxdi, "main");
+			return -ENODEV;
+		}
+	}
+	/*
+	 * - the timer counter stops/is stopped if
+	 *   - its overflow flag is set (TCO in DSR)
+	 *      -> clear overflow bit to make it count again
+	 *   - NVF is set in DSR
+	 *      -> clear non-valid bit to make it count again
+	 *   - its TCE (DCR) is cleared
+	 *      -> set TCE to make it count
+	 *   - it was never set before
+	 *      -> write a time into it (required again if the NVF was set)
+	 */
+	/* state handled */
+	di_write_busy_wait(imxdi, DSR_NVF, DSR);
+	/* clear overflow flag */
+	di_write_busy_wait(imxdi, DSR_TCO, DSR);
+	/* enable the counter */
+	di_write_busy_wait(imxdi, dcr | DCR_TCE, DCR);
+	/* set and trigger it to make it count */
+	di_write_busy_wait(imxdi, sec, DTCMR);
+
+	/* now prepare for the valid state */
+	return di_handle_valid_state(imxdi, __raw_readl(imxdi->ioaddr + DSR));
+}
+
+static int di_handle_invalid_and_failure_state(struct imxdi_dev *imxdi, u32 dsr)
+{
+	u32 dcr;
+
+	/*
+	 * now we must first remove the tamper sources in order to get the
+	 * device out of the "FAILURE STATE"
+	 * To disable any of the following sources we need to modify the DTCR
+	 */
+	if (dsr & (DSR_WTD | DSR_ETBD | DSR_ETAD | DSR_EBD | DSR_SAD |
+			DSR_TTD | DSR_CTD | DSR_VTD | DSR_MCO | DSR_TCO)) {
+		dcr = __raw_readl(imxdi->ioaddr + DCR);
+		if (dcr & DCR_TDCHL) {
+			/*
+			 * the tamper register is locked. We cannot disable the
+			 * tamper detection. The TDCHL can only be reset by a
+			 * DRYICE POR, but we cannot force a DRYICE POR in
+			 * softwere because we are still in "FAILURE STATE".
+			 * We need a DRYICE POR via battery power cycling....
+			 */
+			/*
+			 * out of luck!
+			 * we cannot disable them without a DRYICE POR
+			 */
+			di_what_is_to_be_done(imxdi, "battery");
+			return -ENODEV;
+		}
+		if (dcr & DCR_TDCSL) {
+			/* a soft lock can be removed by a SYSTEM POR */
+			di_what_is_to_be_done(imxdi, "main");
+			return -ENODEV;
+		}
+	}
+
+	/* disable all sources */
+	di_write_busy_wait(imxdi, 0x00000000, DTCR);
+
+	/* clear the status bits now */
+	di_write_busy_wait(imxdi, dsr & (DSR_WTD | DSR_ETBD | DSR_ETAD |
+			DSR_EBD | DSR_SAD | DSR_TTD | DSR_CTD | DSR_VTD |
+			DSR_MCO | DSR_TCO), DSR);
+
+	dsr = readl(imxdi->ioaddr + DSR);
+	if ((dsr & ~(DSR_NVF | DSR_SVF | DSR_WBF | DSR_WNF |
+			DSR_WCF | DSR_WEF)) != 0)
+		dev_warn(&imxdi->pdev->dev,
+			 "There are still some sources of pain in DSR: %08x!\n",
+			 dsr & ~(DSR_NVF | DSR_SVF | DSR_WBF | DSR_WNF |
+				 DSR_WCF | DSR_WEF));
+
+	/*
+	 * now we are trying to clear the "Security-violation flag" to
+	 * get the DryIce out of this state
+	 */
+	di_write_busy_wait(imxdi, DSR_SVF, DSR);
+
+	/* success? */
+	dsr = readl(imxdi->ioaddr + DSR);
+	if (dsr & DSR_SVF) {
+		dev_crit(&imxdi->pdev->dev,
+			 "Cannot clear the security violation flag. We are ending up in an endless loop!\n");
+		/* last resort */
+		di_what_is_to_be_done(imxdi, "battery");
+		return -ENODEV;
+	}
+
+	/*
+	 * now we have left the "FAILURE STATE" and ending up in the
+	 * "NON-VALID STATE" time to recover everything
+	 */
+	return di_handle_invalid_state(imxdi, dsr);
+}
+
+static int di_handle_state(struct imxdi_dev *imxdi)
+{
+	int rc;
+	u32 dsr;
+
+	dsr = readl(imxdi->ioaddr + DSR);
+
+	switch (dsr & (DSR_NVF | DSR_SVF)) {
+	case DSR_NVF:
+		dev_warn(&imxdi->pdev->dev, "Invalid stated unit detected\n");
+		rc = di_handle_invalid_state(imxdi, dsr);
+		break;
+	case DSR_SVF:
+		dev_warn(&imxdi->pdev->dev, "Failure stated unit detected\n");
+		rc = di_handle_failure_state(imxdi, dsr);
+		break;
+	case DSR_NVF | DSR_SVF:
+		dev_warn(&imxdi->pdev->dev,
+			 "Failure+Invalid stated unit detected\n");
+		rc = di_handle_invalid_and_failure_state(imxdi, dsr);
+		break;
+	default:
+		dev_notice(&imxdi->pdev->dev, "Unlocked unit detected\n");
+		rc = di_handle_valid_state(imxdi, dsr);
+	}
+
+	return rc;
+}
+
+/*
+ * enable a dryice interrupt
+ */
+static void di_int_enable(struct imxdi_dev *imxdi, u32 intr)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&imxdi->irq_lock, flags);
+	writel(readl(imxdi->ioaddr + DIER) | intr,
+	       imxdi->ioaddr + DIER);
+	spin_unlock_irqrestore(&imxdi->irq_lock, flags);
+}
+
+/*
+ * disable a dryice interrupt
+ */
+static void di_int_disable(struct imxdi_dev *imxdi, u32 intr)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&imxdi->irq_lock, flags);
+	writel(readl(imxdi->ioaddr + DIER) & ~intr,
+	       imxdi->ioaddr + DIER);
+	spin_unlock_irqrestore(&imxdi->irq_lock, flags);
+}
+
+/*
+ * This function attempts to clear the dryice write-error flag.
+ *
+ * A dryice write error is similar to a bus fault and should not occur in
+ * normal operation.  Clearing the flag requires another write, so the root
+ * cause of the problem may need to be fixed before the flag can be cleared.
+ */
+static void clear_write_error(struct imxdi_dev *imxdi)
+{
+	int cnt;
+
+	dev_warn(&imxdi->pdev->dev, "WARNING: Register write error!\n");
+
+	/* clear the write error flag */
+	writel(DSR_WEF, imxdi->ioaddr + DSR);
+
+	/* wait for it to take effect */
+	for (cnt = 0; cnt < 1000; cnt++) {
+		if ((readl(imxdi->ioaddr + DSR) & DSR_WEF) == 0)
+			return;
+		udelay(10);
+	}
+	dev_err(&imxdi->pdev->dev,
+			"ERROR: Cannot clear write-error flag!\n");
+}
+
+/*
+ * Write a dryice register and wait until it completes.
+ *
+ * This function uses interrupts to determine when the
+ * write has completed.
+ */
+static int di_write_wait(struct imxdi_dev *imxdi, u32 val, int reg)
+{
+	int ret;
+	int rc = 0;
+
+	/* serialize register writes */
+	mutex_lock(&imxdi->write_mutex);
+
+	/* enable the write-complete interrupt */
+	di_int_enable(imxdi, DIER_WCIE);
+
+	imxdi->dsr = 0;
+
+	/* do the register write */
+	writel(val, imxdi->ioaddr + reg);
+
+	/* wait for the write to finish */
+	ret = wait_event_interruptible_timeout(imxdi->write_wait,
+			imxdi->dsr & (DSR_WCF | DSR_WEF), msecs_to_jiffies(1));
+	if (ret < 0) {
+		rc = ret;
+		goto out;
+	} else if (ret == 0) {
+		dev_warn(&imxdi->pdev->dev,
+				"Write-wait timeout "
+				"val = 0x%08x reg = 0x%08x\n", val, reg);
+	}
+
+	/* check for write error */
+	if (imxdi->dsr & DSR_WEF) {
+		clear_write_error(imxdi);
+		rc = -EIO;
+	}
+
+out:
+	mutex_unlock(&imxdi->write_mutex);
+
+	return rc;
+}
+
+/*
+ * read the seconds portion of the current time from the dryice time counter
+ */
+static int dryice_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct imxdi_dev *imxdi = dev_get_drvdata(dev);
+	unsigned long now;
+
+	now = readl(imxdi->ioaddr + DTCMR);
+	rtc_time_to_tm(now, tm);
+
+	return 0;
+}
+
+/*
+ * set the seconds portion of dryice time counter and clear the
+ * fractional part.
+ */
+static int dryice_rtc_set_mmss(struct device *dev, unsigned long secs)
+{
+	struct imxdi_dev *imxdi = dev_get_drvdata(dev);
+	u32 dcr, dsr;
+	int rc;
+
+	dcr = readl(imxdi->ioaddr + DCR);
+	dsr = readl(imxdi->ioaddr + DSR);
+
+	if (!(dcr & DCR_TCE) || (dsr & DSR_SVF)) {
+		if (dcr & DCR_TCHL) {
+			/* we are even more out of luck */
+			di_what_is_to_be_done(imxdi, "battery");
+			return -EPERM;
+		}
+		if ((dcr & DCR_TCSL) || (dsr & DSR_SVF)) {
+			/* we are out of luck for now */
+			di_what_is_to_be_done(imxdi, "main");
+			return -EPERM;
+		}
+	}
+
+	/* zero the fractional part first */
+	rc = di_write_wait(imxdi, 0, DTCLR);
+	if (rc != 0)
+		return rc;
+
+	rc = di_write_wait(imxdi, secs, DTCMR);
+	if (rc != 0)
+		return rc;
+
+	return di_write_wait(imxdi, readl(imxdi->ioaddr + DCR) | DCR_TCE, DCR);
+}
+
+static int dryice_rtc_alarm_irq_enable(struct device *dev,
+		unsigned int enabled)
+{
+	struct imxdi_dev *imxdi = dev_get_drvdata(dev);
+
+	if (enabled)
+		di_int_enable(imxdi, DIER_CAIE);
+	else
+		di_int_disable(imxdi, DIER_CAIE);
+
+	return 0;
+}
+
+/*
+ * read the seconds portion of the alarm register.
+ * the fractional part of the alarm register is always zero.
+ */
+static int dryice_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	struct imxdi_dev *imxdi = dev_get_drvdata(dev);
+	u32 dcamr;
+
+	dcamr = readl(imxdi->ioaddr + DCAMR);
+	rtc_time_to_tm(dcamr, &alarm->time);
+
+	/* alarm is enabled if the interrupt is enabled */
+	alarm->enabled = (readl(imxdi->ioaddr + DIER) & DIER_CAIE) != 0;
+
+	/* don't allow the DSR read to mess up DSR_WCF */
+	mutex_lock(&imxdi->write_mutex);
+
+	/* alarm is pending if the alarm flag is set */
+	alarm->pending = (readl(imxdi->ioaddr + DSR) & DSR_CAF) != 0;
+
+	mutex_unlock(&imxdi->write_mutex);
+
+	return 0;
+}
+
+/*
+ * set the seconds portion of dryice alarm register
+ */
+static int dryice_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	struct imxdi_dev *imxdi = dev_get_drvdata(dev);
+	unsigned long now;
+	unsigned long alarm_time;
+	int rc;
+
+	rc = rtc_tm_to_time(&alarm->time, &alarm_time);
+	if (rc)
+		return rc;
+
+	/* don't allow setting alarm in the past */
+	now = readl(imxdi->ioaddr + DTCMR);
+	if (alarm_time < now)
+		return -EINVAL;
+
+	/* write the new alarm time */
+	rc = di_write_wait(imxdi, (u32)alarm_time, DCAMR);
+	if (rc)
+		return rc;
+
+	if (alarm->enabled)
+		di_int_enable(imxdi, DIER_CAIE);  /* enable alarm intr */
+	else
+		di_int_disable(imxdi, DIER_CAIE); /* disable alarm intr */
+
+	return 0;
+}
+
+static const struct rtc_class_ops dryice_rtc_ops = {
+	.read_time		= dryice_rtc_read_time,
+	.set_mmss		= dryice_rtc_set_mmss,
+	.alarm_irq_enable	= dryice_rtc_alarm_irq_enable,
+	.read_alarm		= dryice_rtc_read_alarm,
+	.set_alarm		= dryice_rtc_set_alarm,
+};
+
+/*
+ * interrupt handler for dryice "normal" and security violation interrupt
+ */
+static irqreturn_t dryice_irq(int irq, void *dev_id)
+{
+	struct imxdi_dev *imxdi = dev_id;
+	u32 dsr, dier;
+	irqreturn_t rc = IRQ_NONE;
+
+	dier = readl(imxdi->ioaddr + DIER);
+	dsr = readl(imxdi->ioaddr + DSR);
+
+	/* handle the security violation event */
+	if (dier & DIER_SVIE) {
+		if (dsr & DSR_SVF) {
+			/*
+			 * Disable the interrupt when this kind of event has
+			 * happened.
+			 * There cannot be more than one event of this type,
+			 * because it needs a complex state change
+			 * including a main power cycle to get again out of
+			 * this state.
+			 */
+			di_int_disable(imxdi, DIER_SVIE);
+			/* report the violation */
+			di_report_tamper_info(imxdi, dsr);
+			rc = IRQ_HANDLED;
+		}
+	}
+
+	/* handle write complete and write error cases */
+	if (dier & DIER_WCIE) {
+		/*If the write wait queue is empty then there is no pending
+		  operations. It means the interrupt is for DryIce -Security.
+		  IRQ must be returned as none.*/
+		if (list_empty_careful(&imxdi->write_wait.head))
+			return rc;
+
+		/* DSR_WCF clears itself on DSR read */
+		if (dsr & (DSR_WCF | DSR_WEF)) {
+			/* mask the interrupt */
+			di_int_disable(imxdi, DIER_WCIE);
+
+			/* save the dsr value for the wait queue */
+			imxdi->dsr |= dsr;
+
+			wake_up_interruptible(&imxdi->write_wait);
+			rc = IRQ_HANDLED;
+		}
+	}
+
+	/* handle the alarm case */
+	if (dier & DIER_CAIE) {
+		/* DSR_WCF clears itself on DSR read */
+		if (dsr & DSR_CAF) {
+			/* mask the interrupt */
+			di_int_disable(imxdi, DIER_CAIE);
+
+			/* finish alarm in user context */
+			schedule_work(&imxdi->work);
+			rc = IRQ_HANDLED;
+		}
+	}
+	return rc;
+}
+
+/*
+ * post the alarm event from user context so it can sleep
+ * on the write completion.
+ */
+static void dryice_work(struct work_struct *work)
+{
+	struct imxdi_dev *imxdi = container_of(work,
+			struct imxdi_dev, work);
+
+	/* dismiss the interrupt (ignore error) */
+	di_write_wait(imxdi, DSR_CAF, DSR);
+
+	/* pass the alarm event to the rtc framework. */
+	rtc_update_irq(imxdi->rtc, 1, RTC_AF | RTC_IRQF);
+}
+
+/*
+ * probe for dryice rtc device
+ */
+static int __init dryice_rtc_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct imxdi_dev *imxdi;
+	int norm_irq, sec_irq;
+	int rc;
+
+	imxdi = devm_kzalloc(&pdev->dev, sizeof(*imxdi), GFP_KERNEL);
+	if (!imxdi)
+		return -ENOMEM;
+
+	imxdi->pdev = pdev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	imxdi->ioaddr = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(imxdi->ioaddr))
+		return PTR_ERR(imxdi->ioaddr);
+
+	spin_lock_init(&imxdi->irq_lock);
+
+	norm_irq = platform_get_irq(pdev, 0);
+	if (norm_irq < 0)
+		return norm_irq;
+
+	/* the 2nd irq is the security violation irq
+	 * make this optional, don't break the device tree ABI
+	 */
+	sec_irq = platform_get_irq(pdev, 1);
+	if (sec_irq <= 0)
+		sec_irq = IRQ_NOTCONNECTED;
+
+	init_waitqueue_head(&imxdi->write_wait);
+
+	INIT_WORK(&imxdi->work, dryice_work);
+
+	mutex_init(&imxdi->write_mutex);
+
+	imxdi->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(imxdi->clk))
+		return PTR_ERR(imxdi->clk);
+	rc = clk_prepare_enable(imxdi->clk);
+	if (rc)
+		return rc;
+
+	/*
+	 * Initialize dryice hardware
+	 */
+
+	/* mask all interrupts */
+	writel(0, imxdi->ioaddr + DIER);
+
+	rc = di_handle_state(imxdi);
+	if (rc != 0)
+		goto err;
+
+	rc = devm_request_irq(&pdev->dev, norm_irq, dryice_irq,
+			      IRQF_SHARED, pdev->name, imxdi);
+	if (rc) {
+		dev_warn(&pdev->dev, "interrupt not available.\n");
+		goto err;
+	}
+
+	rc = devm_request_irq(&pdev->dev, sec_irq, dryice_irq,
+			      IRQF_SHARED, pdev->name, imxdi);
+	if (rc) {
+		dev_warn(&pdev->dev, "security violation interrupt not available.\n");
+		/* this is not an error, see above */
+	}
+
+	platform_set_drvdata(pdev, imxdi);
+	imxdi->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
+				  &dryice_rtc_ops, THIS_MODULE);
+	if (IS_ERR(imxdi->rtc)) {
+		rc = PTR_ERR(imxdi->rtc);
+		goto err;
+	}
+
+	return 0;
+
+err:
+	clk_disable_unprepare(imxdi->clk);
+
+	return rc;
+}
+
+static int __exit dryice_rtc_remove(struct platform_device *pdev)
+{
+	struct imxdi_dev *imxdi = platform_get_drvdata(pdev);
+
+	flush_work(&imxdi->work);
+
+	/* mask all interrupts */
+	writel(0, imxdi->ioaddr + DIER);
+
+	clk_disable_unprepare(imxdi->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id dryice_dt_ids[] = {
+	{ .compatible = "fsl,imx25-rtc" },
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, dryice_dt_ids);
+#endif
+
+static struct platform_driver dryice_rtc_driver = {
+	.driver = {
+		   .name = "imxdi_rtc",
+		   .of_match_table = of_match_ptr(dryice_dt_ids),
+		   },
+	.remove = __exit_p(dryice_rtc_remove),
+};
+
+module_platform_driver_probe(dryice_rtc_driver, dryice_rtc_probe);
+
+MODULE_AUTHOR("Freescale Semiconductor, Inc.");
+MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
+MODULE_DESCRIPTION("IMX DryIce Realtime Clock Driver (RTC)");
+MODULE_LICENSE("GPL");