Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 1440 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-ds1685.c b/drivers/rtc/rtc-ds1685.c
new file mode 100644
index 000000000..5fc8e36b1
--- /dev/null
+++ b/drivers/rtc/rtc-ds1685.c
@@ -0,0 +1,1440 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * An rtc driver for the Dallas/Maxim DS1685/DS1687 and related real-time
+ * chips.
+ *
+ * Copyright (C) 2011-2014 Joshua Kinard <linux@kumba.dev>.
+ * Copyright (C) 2009 Matthias Fuchs <matthias.fuchs@esd-electronics.com>.
+ *
+ * References:
+ *    DS1685/DS1687 3V/5V Real-Time Clocks, 19-5215, Rev 4/10.
+ *    DS17x85/DS17x87 3V/5V Real-Time Clocks, 19-5222, Rev 4/10.
+ *    DS1689/DS1693 3V/5V Serialized Real-Time Clocks, Rev 112105.
+ *    Application Note 90, Using the Multiplex Bus RTC Extended Features.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/bcd.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/workqueue.h>
+
+#include <linux/rtc/ds1685.h>
+
+#ifdef CONFIG_PROC_FS
+#include <linux/proc_fs.h>
+#endif
+
+
+/* ----------------------------------------------------------------------- */
+/*
+ *  Standard read/write
+ *  all registers are mapped in CPU address space
+ */
+
+/**
+ * ds1685_read - read a value from an rtc register.
+ * @rtc: pointer to the ds1685 rtc structure.
+ * @reg: the register address to read.
+ */
+static u8
+ds1685_read(struct ds1685_priv *rtc, int reg)
+{
+	return readb((u8 __iomem *)rtc->regs +
+		     (reg * rtc->regstep));
+}
+
+/**
+ * ds1685_write - write a value to an rtc register.
+ * @rtc: pointer to the ds1685 rtc structure.
+ * @reg: the register address to write.
+ * @value: value to write to the register.
+ */
+static void
+ds1685_write(struct ds1685_priv *rtc, int reg, u8 value)
+{
+	writeb(value, ((u8 __iomem *)rtc->regs +
+		       (reg * rtc->regstep)));
+}
+/* ----------------------------------------------------------------------- */
+
+/*
+ * Indirect read/write functions
+ * access happens via address and data register mapped in CPU address space
+ */
+
+/**
+ * ds1685_indirect_read - read a value from an rtc register.
+ * @rtc: pointer to the ds1685 rtc structure.
+ * @reg: the register address to read.
+ */
+static u8
+ds1685_indirect_read(struct ds1685_priv *rtc, int reg)
+{
+	writeb(reg, rtc->regs);
+	return readb(rtc->data);
+}
+
+/**
+ * ds1685_indirect_write - write a value to an rtc register.
+ * @rtc: pointer to the ds1685 rtc structure.
+ * @reg: the register address to write.
+ * @value: value to write to the register.
+ */
+static void
+ds1685_indirect_write(struct ds1685_priv *rtc, int reg, u8 value)
+{
+	writeb(reg, rtc->regs);
+	writeb(value, rtc->data);
+}
+
+/* ----------------------------------------------------------------------- */
+/* Inlined functions */
+
+/**
+ * ds1685_rtc_bcd2bin - bcd2bin wrapper in case platform doesn't support BCD.
+ * @rtc: pointer to the ds1685 rtc structure.
+ * @val: u8 time value to consider converting.
+ * @bcd_mask: u8 mask value if BCD mode is used.
+ * @bin_mask: u8 mask value if BIN mode is used.
+ *
+ * Returns the value, converted to BIN if originally in BCD and bcd_mode TRUE.
+ */
+static inline u8
+ds1685_rtc_bcd2bin(struct ds1685_priv *rtc, u8 val, u8 bcd_mask, u8 bin_mask)
+{
+	if (rtc->bcd_mode)
+		return (bcd2bin(val) & bcd_mask);
+
+	return (val & bin_mask);
+}
+
+/**
+ * ds1685_rtc_bin2bcd - bin2bcd wrapper in case platform doesn't support BCD.
+ * @rtc: pointer to the ds1685 rtc structure.
+ * @val: u8 time value to consider converting.
+ * @bin_mask: u8 mask value if BIN mode is used.
+ * @bcd_mask: u8 mask value if BCD mode is used.
+ *
+ * Returns the value, converted to BCD if originally in BIN and bcd_mode TRUE.
+ */
+static inline u8
+ds1685_rtc_bin2bcd(struct ds1685_priv *rtc, u8 val, u8 bin_mask, u8 bcd_mask)
+{
+	if (rtc->bcd_mode)
+		return (bin2bcd(val) & bcd_mask);
+
+	return (val & bin_mask);
+}
+
+/**
+ * ds1685_rtc_check_mday - check validity of the day of month.
+ * @rtc: pointer to the ds1685 rtc structure.
+ * @mday: day of month.
+ *
+ * Returns -EDOM if the day of month is not within 1..31 range.
+ */
+static inline int
+ds1685_rtc_check_mday(struct ds1685_priv *rtc, u8 mday)
+{
+	if (rtc->bcd_mode) {
+		if (mday < 0x01 || mday > 0x31 || (mday & 0x0f) > 0x09)
+			return -EDOM;
+	} else {
+		if (mday < 1 || mday > 31)
+			return -EDOM;
+	}
+	return 0;
+}
+
+/**
+ * ds1685_rtc_switch_to_bank0 - switch the rtc to bank 0.
+ * @rtc: pointer to the ds1685 rtc structure.
+ */
+static inline void
+ds1685_rtc_switch_to_bank0(struct ds1685_priv *rtc)
+{
+	rtc->write(rtc, RTC_CTRL_A,
+		   (rtc->read(rtc, RTC_CTRL_A) & ~(RTC_CTRL_A_DV0)));
+}
+
+/**
+ * ds1685_rtc_switch_to_bank1 - switch the rtc to bank 1.
+ * @rtc: pointer to the ds1685 rtc structure.
+ */
+static inline void
+ds1685_rtc_switch_to_bank1(struct ds1685_priv *rtc)
+{
+	rtc->write(rtc, RTC_CTRL_A,
+		   (rtc->read(rtc, RTC_CTRL_A) | RTC_CTRL_A_DV0));
+}
+
+/**
+ * ds1685_rtc_begin_data_access - prepare the rtc for data access.
+ * @rtc: pointer to the ds1685 rtc structure.
+ *
+ * This takes several steps to prepare the rtc for access to get/set time
+ * and alarm values from the rtc registers:
+ *  - Sets the SET bit in Control Register B.
+ *  - Reads Ext Control Register 4A and checks the INCR bit.
+ *  - If INCR is active, a short delay is added before Ext Control Register 4A
+ *    is read again in a loop until INCR is inactive.
+ *  - Switches the rtc to bank 1.  This allows access to all relevant
+ *    data for normal rtc operation, as bank 0 contains only the nvram.
+ */
+static inline void
+ds1685_rtc_begin_data_access(struct ds1685_priv *rtc)
+{
+	/* Set the SET bit in Ctrl B */
+	rtc->write(rtc, RTC_CTRL_B,
+		   (rtc->read(rtc, RTC_CTRL_B) | RTC_CTRL_B_SET));
+
+	/* Switch to Bank 1 */
+	ds1685_rtc_switch_to_bank1(rtc);
+
+	/* Read Ext Ctrl 4A and check the INCR bit to avoid a lockout. */
+	while (rtc->read(rtc, RTC_EXT_CTRL_4A) & RTC_CTRL_4A_INCR)
+		cpu_relax();
+}
+
+/**
+ * ds1685_rtc_end_data_access - end data access on the rtc.
+ * @rtc: pointer to the ds1685 rtc structure.
+ *
+ * This ends what was started by ds1685_rtc_begin_data_access:
+ *  - Switches the rtc back to bank 0.
+ *  - Clears the SET bit in Control Register B.
+ */
+static inline void
+ds1685_rtc_end_data_access(struct ds1685_priv *rtc)
+{
+	/* Switch back to Bank 0 */
+	ds1685_rtc_switch_to_bank0(rtc);
+
+	/* Clear the SET bit in Ctrl B */
+	rtc->write(rtc, RTC_CTRL_B,
+		   (rtc->read(rtc, RTC_CTRL_B) & ~(RTC_CTRL_B_SET)));
+}
+
+/**
+ * ds1685_rtc_get_ssn - retrieve the silicon serial number.
+ * @rtc: pointer to the ds1685 rtc structure.
+ * @ssn: u8 array to hold the bits of the silicon serial number.
+ *
+ * This number starts at 0x40, and is 8-bytes long, ending at 0x47. The
+ * first byte is the model number, the next six bytes are the serial number
+ * digits, and the final byte is a CRC check byte.  Together, they form the
+ * silicon serial number.
+ *
+ * These values are stored in bank1, so ds1685_rtc_switch_to_bank1 must be
+ * called first before calling this function, else data will be read out of
+ * the bank0 NVRAM.  Be sure to call ds1685_rtc_switch_to_bank0 when done.
+ */
+static inline void
+ds1685_rtc_get_ssn(struct ds1685_priv *rtc, u8 *ssn)
+{
+	ssn[0] = rtc->read(rtc, RTC_BANK1_SSN_MODEL);
+	ssn[1] = rtc->read(rtc, RTC_BANK1_SSN_BYTE_1);
+	ssn[2] = rtc->read(rtc, RTC_BANK1_SSN_BYTE_2);
+	ssn[3] = rtc->read(rtc, RTC_BANK1_SSN_BYTE_3);
+	ssn[4] = rtc->read(rtc, RTC_BANK1_SSN_BYTE_4);
+	ssn[5] = rtc->read(rtc, RTC_BANK1_SSN_BYTE_5);
+	ssn[6] = rtc->read(rtc, RTC_BANK1_SSN_BYTE_6);
+	ssn[7] = rtc->read(rtc, RTC_BANK1_SSN_CRC);
+}
+/* ----------------------------------------------------------------------- */
+
+
+/* ----------------------------------------------------------------------- */
+/* Read/Set Time & Alarm functions */
+
+/**
+ * ds1685_rtc_read_time - reads the time registers.
+ * @dev: pointer to device structure.
+ * @tm: pointer to rtc_time structure.
+ */
+static int
+ds1685_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct ds1685_priv *rtc = dev_get_drvdata(dev);
+	u8 century;
+	u8 seconds, minutes, hours, wday, mday, month, years;
+
+	/* Fetch the time info from the RTC registers. */
+	ds1685_rtc_begin_data_access(rtc);
+	seconds = rtc->read(rtc, RTC_SECS);
+	minutes = rtc->read(rtc, RTC_MINS);
+	hours   = rtc->read(rtc, RTC_HRS);
+	wday    = rtc->read(rtc, RTC_WDAY);
+	mday    = rtc->read(rtc, RTC_MDAY);
+	month   = rtc->read(rtc, RTC_MONTH);
+	years   = rtc->read(rtc, RTC_YEAR);
+	century = rtc->read(rtc, RTC_CENTURY);
+	ds1685_rtc_end_data_access(rtc);
+
+	/* bcd2bin if needed, perform fixups, and store to rtc_time. */
+	years        = ds1685_rtc_bcd2bin(rtc, years, RTC_YEAR_BCD_MASK,
+					  RTC_YEAR_BIN_MASK);
+	century      = ds1685_rtc_bcd2bin(rtc, century, RTC_CENTURY_MASK,
+					  RTC_CENTURY_MASK);
+	tm->tm_sec   = ds1685_rtc_bcd2bin(rtc, seconds, RTC_SECS_BCD_MASK,
+					  RTC_SECS_BIN_MASK);
+	tm->tm_min   = ds1685_rtc_bcd2bin(rtc, minutes, RTC_MINS_BCD_MASK,
+					  RTC_MINS_BIN_MASK);
+	tm->tm_hour  = ds1685_rtc_bcd2bin(rtc, hours, RTC_HRS_24_BCD_MASK,
+					  RTC_HRS_24_BIN_MASK);
+	tm->tm_wday  = (ds1685_rtc_bcd2bin(rtc, wday, RTC_WDAY_MASK,
+					   RTC_WDAY_MASK) - 1);
+	tm->tm_mday  = ds1685_rtc_bcd2bin(rtc, mday, RTC_MDAY_BCD_MASK,
+					  RTC_MDAY_BIN_MASK);
+	tm->tm_mon   = (ds1685_rtc_bcd2bin(rtc, month, RTC_MONTH_BCD_MASK,
+					   RTC_MONTH_BIN_MASK) - 1);
+	tm->tm_year  = ((years + (century * 100)) - 1900);
+	tm->tm_yday  = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
+	tm->tm_isdst = 0; /* RTC has hardcoded timezone, so don't use. */
+
+	return 0;
+}
+
+/**
+ * ds1685_rtc_set_time - sets the time registers.
+ * @dev: pointer to device structure.
+ * @tm: pointer to rtc_time structure.
+ */
+static int
+ds1685_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct ds1685_priv *rtc = dev_get_drvdata(dev);
+	u8 ctrlb, seconds, minutes, hours, wday, mday, month, years, century;
+
+	/* Fetch the time info from rtc_time. */
+	seconds = ds1685_rtc_bin2bcd(rtc, tm->tm_sec, RTC_SECS_BIN_MASK,
+				     RTC_SECS_BCD_MASK);
+	minutes = ds1685_rtc_bin2bcd(rtc, tm->tm_min, RTC_MINS_BIN_MASK,
+				     RTC_MINS_BCD_MASK);
+	hours   = ds1685_rtc_bin2bcd(rtc, tm->tm_hour, RTC_HRS_24_BIN_MASK,
+				     RTC_HRS_24_BCD_MASK);
+	wday    = ds1685_rtc_bin2bcd(rtc, (tm->tm_wday + 1), RTC_WDAY_MASK,
+				     RTC_WDAY_MASK);
+	mday    = ds1685_rtc_bin2bcd(rtc, tm->tm_mday, RTC_MDAY_BIN_MASK,
+				     RTC_MDAY_BCD_MASK);
+	month   = ds1685_rtc_bin2bcd(rtc, (tm->tm_mon + 1), RTC_MONTH_BIN_MASK,
+				     RTC_MONTH_BCD_MASK);
+	years   = ds1685_rtc_bin2bcd(rtc, (tm->tm_year % 100),
+				     RTC_YEAR_BIN_MASK, RTC_YEAR_BCD_MASK);
+	century = ds1685_rtc_bin2bcd(rtc, ((tm->tm_year + 1900) / 100),
+				     RTC_CENTURY_MASK, RTC_CENTURY_MASK);
+
+	/*
+	 * Perform Sanity Checks:
+	 *   - Months: !> 12, Month Day != 0.
+	 *   - Month Day !> Max days in current month.
+	 *   - Hours !>= 24, Mins !>= 60, Secs !>= 60, & Weekday !> 7.
+	 */
+	if ((tm->tm_mon > 11) || (mday == 0))
+		return -EDOM;
+
+	if (tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year))
+		return -EDOM;
+
+	if ((tm->tm_hour >= 24) || (tm->tm_min >= 60) ||
+	    (tm->tm_sec >= 60)  || (wday > 7))
+		return -EDOM;
+
+	/*
+	 * Set the data mode to use and store the time values in the
+	 * RTC registers.
+	 */
+	ds1685_rtc_begin_data_access(rtc);
+	ctrlb = rtc->read(rtc, RTC_CTRL_B);
+	if (rtc->bcd_mode)
+		ctrlb &= ~(RTC_CTRL_B_DM);
+	else
+		ctrlb |= RTC_CTRL_B_DM;
+	rtc->write(rtc, RTC_CTRL_B, ctrlb);
+	rtc->write(rtc, RTC_SECS, seconds);
+	rtc->write(rtc, RTC_MINS, minutes);
+	rtc->write(rtc, RTC_HRS, hours);
+	rtc->write(rtc, RTC_WDAY, wday);
+	rtc->write(rtc, RTC_MDAY, mday);
+	rtc->write(rtc, RTC_MONTH, month);
+	rtc->write(rtc, RTC_YEAR, years);
+	rtc->write(rtc, RTC_CENTURY, century);
+	ds1685_rtc_end_data_access(rtc);
+
+	return 0;
+}
+
+/**
+ * ds1685_rtc_read_alarm - reads the alarm registers.
+ * @dev: pointer to device structure.
+ * @alrm: pointer to rtc_wkalrm structure.
+ *
+ * There are three primary alarm registers: seconds, minutes, and hours.
+ * A fourth alarm register for the month date is also available in bank1 for
+ * kickstart/wakeup features.  The DS1685/DS1687 manual states that a
+ * "don't care" value ranging from 0xc0 to 0xff may be written into one or
+ * more of the three alarm bytes to act as a wildcard value.  The fourth
+ * byte doesn't support a "don't care" value.
+ */
+static int
+ds1685_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct ds1685_priv *rtc = dev_get_drvdata(dev);
+	u8 seconds, minutes, hours, mday, ctrlb, ctrlc;
+	int ret;
+
+	/* Fetch the alarm info from the RTC alarm registers. */
+	ds1685_rtc_begin_data_access(rtc);
+	seconds	= rtc->read(rtc, RTC_SECS_ALARM);
+	minutes	= rtc->read(rtc, RTC_MINS_ALARM);
+	hours	= rtc->read(rtc, RTC_HRS_ALARM);
+	mday	= rtc->read(rtc, RTC_MDAY_ALARM);
+	ctrlb	= rtc->read(rtc, RTC_CTRL_B);
+	ctrlc	= rtc->read(rtc, RTC_CTRL_C);
+	ds1685_rtc_end_data_access(rtc);
+
+	/* Check the month date for validity. */
+	ret = ds1685_rtc_check_mday(rtc, mday);
+	if (ret)
+		return ret;
+
+	/*
+	 * Check the three alarm bytes.
+	 *
+	 * The Linux RTC system doesn't support the "don't care" capability
+	 * of this RTC chip.  We check for it anyways in case support is
+	 * added in the future and only assign when we care.
+	 */
+	if (likely(seconds < 0xc0))
+		alrm->time.tm_sec = ds1685_rtc_bcd2bin(rtc, seconds,
+						       RTC_SECS_BCD_MASK,
+						       RTC_SECS_BIN_MASK);
+
+	if (likely(minutes < 0xc0))
+		alrm->time.tm_min = ds1685_rtc_bcd2bin(rtc, minutes,
+						       RTC_MINS_BCD_MASK,
+						       RTC_MINS_BIN_MASK);
+
+	if (likely(hours < 0xc0))
+		alrm->time.tm_hour = ds1685_rtc_bcd2bin(rtc, hours,
+							RTC_HRS_24_BCD_MASK,
+							RTC_HRS_24_BIN_MASK);
+
+	/* Write the data to rtc_wkalrm. */
+	alrm->time.tm_mday = ds1685_rtc_bcd2bin(rtc, mday, RTC_MDAY_BCD_MASK,
+						RTC_MDAY_BIN_MASK);
+	alrm->enabled = !!(ctrlb & RTC_CTRL_B_AIE);
+	alrm->pending = !!(ctrlc & RTC_CTRL_C_AF);
+
+	return 0;
+}
+
+/**
+ * ds1685_rtc_set_alarm - sets the alarm in registers.
+ * @dev: pointer to device structure.
+ * @alrm: pointer to rtc_wkalrm structure.
+ */
+static int
+ds1685_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct ds1685_priv *rtc = dev_get_drvdata(dev);
+	u8 ctrlb, seconds, minutes, hours, mday;
+	int ret;
+
+	/* Fetch the alarm info and convert to BCD. */
+	seconds	= ds1685_rtc_bin2bcd(rtc, alrm->time.tm_sec,
+				     RTC_SECS_BIN_MASK,
+				     RTC_SECS_BCD_MASK);
+	minutes	= ds1685_rtc_bin2bcd(rtc, alrm->time.tm_min,
+				     RTC_MINS_BIN_MASK,
+				     RTC_MINS_BCD_MASK);
+	hours	= ds1685_rtc_bin2bcd(rtc, alrm->time.tm_hour,
+				     RTC_HRS_24_BIN_MASK,
+				     RTC_HRS_24_BCD_MASK);
+	mday	= ds1685_rtc_bin2bcd(rtc, alrm->time.tm_mday,
+				     RTC_MDAY_BIN_MASK,
+				     RTC_MDAY_BCD_MASK);
+
+	/* Check the month date for validity. */
+	ret = ds1685_rtc_check_mday(rtc, mday);
+	if (ret)
+		return ret;
+
+	/*
+	 * Check the three alarm bytes.
+	 *
+	 * The Linux RTC system doesn't support the "don't care" capability
+	 * of this RTC chip because rtc_valid_tm tries to validate every
+	 * field, and we only support four fields.  We put the support
+	 * here anyways for the future.
+	 */
+	if (unlikely(seconds >= 0xc0))
+		seconds = 0xff;
+
+	if (unlikely(minutes >= 0xc0))
+		minutes = 0xff;
+
+	if (unlikely(hours >= 0xc0))
+		hours = 0xff;
+
+	alrm->time.tm_mon	= -1;
+	alrm->time.tm_year	= -1;
+	alrm->time.tm_wday	= -1;
+	alrm->time.tm_yday	= -1;
+	alrm->time.tm_isdst	= -1;
+
+	/* Disable the alarm interrupt first. */
+	ds1685_rtc_begin_data_access(rtc);
+	ctrlb = rtc->read(rtc, RTC_CTRL_B);
+	rtc->write(rtc, RTC_CTRL_B, (ctrlb & ~(RTC_CTRL_B_AIE)));
+
+	/* Read ctrlc to clear RTC_CTRL_C_AF. */
+	rtc->read(rtc, RTC_CTRL_C);
+
+	/*
+	 * Set the data mode to use and store the time values in the
+	 * RTC registers.
+	 */
+	ctrlb = rtc->read(rtc, RTC_CTRL_B);
+	if (rtc->bcd_mode)
+		ctrlb &= ~(RTC_CTRL_B_DM);
+	else
+		ctrlb |= RTC_CTRL_B_DM;
+	rtc->write(rtc, RTC_CTRL_B, ctrlb);
+	rtc->write(rtc, RTC_SECS_ALARM, seconds);
+	rtc->write(rtc, RTC_MINS_ALARM, minutes);
+	rtc->write(rtc, RTC_HRS_ALARM, hours);
+	rtc->write(rtc, RTC_MDAY_ALARM, mday);
+
+	/* Re-enable the alarm if needed. */
+	if (alrm->enabled) {
+		ctrlb = rtc->read(rtc, RTC_CTRL_B);
+		ctrlb |= RTC_CTRL_B_AIE;
+		rtc->write(rtc, RTC_CTRL_B, ctrlb);
+	}
+
+	/* Done! */
+	ds1685_rtc_end_data_access(rtc);
+
+	return 0;
+}
+/* ----------------------------------------------------------------------- */
+
+
+/* ----------------------------------------------------------------------- */
+/* /dev/rtcX Interface functions */
+
+/**
+ * ds1685_rtc_alarm_irq_enable - replaces ioctl() RTC_AIE on/off.
+ * @dev: pointer to device structure.
+ * @enabled: flag indicating whether to enable or disable.
+ */
+static int
+ds1685_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct ds1685_priv *rtc = dev_get_drvdata(dev);
+
+	/* Flip the requisite interrupt-enable bit. */
+	if (enabled)
+		rtc->write(rtc, RTC_CTRL_B, (rtc->read(rtc, RTC_CTRL_B) |
+					     RTC_CTRL_B_AIE));
+	else
+		rtc->write(rtc, RTC_CTRL_B, (rtc->read(rtc, RTC_CTRL_B) &
+					     ~(RTC_CTRL_B_AIE)));
+
+	/* Read Control C to clear all the flag bits. */
+	rtc->read(rtc, RTC_CTRL_C);
+
+	return 0;
+}
+/* ----------------------------------------------------------------------- */
+
+
+/* ----------------------------------------------------------------------- */
+/* IRQ handler */
+
+/**
+ * ds1685_rtc_extended_irq - take care of extended interrupts
+ * @rtc: pointer to the ds1685 rtc structure.
+ * @pdev: platform device pointer.
+ */
+static void
+ds1685_rtc_extended_irq(struct ds1685_priv *rtc, struct platform_device *pdev)
+{
+	u8 ctrl4a, ctrl4b;
+
+	ds1685_rtc_switch_to_bank1(rtc);
+	ctrl4a = rtc->read(rtc, RTC_EXT_CTRL_4A);
+	ctrl4b = rtc->read(rtc, RTC_EXT_CTRL_4B);
+
+	/*
+	 * Check for a kickstart interrupt. With Vcc applied, this
+	 * typically means that the power button was pressed, so we
+	 * begin the shutdown sequence.
+	 */
+	if ((ctrl4b & RTC_CTRL_4B_KSE) && (ctrl4a & RTC_CTRL_4A_KF)) {
+		/* Briefly disable kickstarts to debounce button presses. */
+		rtc->write(rtc, RTC_EXT_CTRL_4B,
+			   (rtc->read(rtc, RTC_EXT_CTRL_4B) &
+			    ~(RTC_CTRL_4B_KSE)));
+
+		/* Clear the kickstart flag. */
+		rtc->write(rtc, RTC_EXT_CTRL_4A,
+			   (ctrl4a & ~(RTC_CTRL_4A_KF)));
+
+
+		/*
+		 * Sleep 500ms before re-enabling kickstarts.  This allows
+		 * adequate time to avoid reading signal jitter as additional
+		 * button presses.
+		 */
+		msleep(500);
+		rtc->write(rtc, RTC_EXT_CTRL_4B,
+			   (rtc->read(rtc, RTC_EXT_CTRL_4B) |
+			    RTC_CTRL_4B_KSE));
+
+		/* Call the platform pre-poweroff function. Else, shutdown. */
+		if (rtc->prepare_poweroff != NULL)
+			rtc->prepare_poweroff();
+		else
+			ds1685_rtc_poweroff(pdev);
+	}
+
+	/*
+	 * Check for a wake-up interrupt.  With Vcc applied, this is
+	 * essentially a second alarm interrupt, except it takes into
+	 * account the 'date' register in bank1 in addition to the
+	 * standard three alarm registers.
+	 */
+	if ((ctrl4b & RTC_CTRL_4B_WIE) && (ctrl4a & RTC_CTRL_4A_WF)) {
+		rtc->write(rtc, RTC_EXT_CTRL_4A,
+			   (ctrl4a & ~(RTC_CTRL_4A_WF)));
+
+		/* Call the platform wake_alarm function if defined. */
+		if (rtc->wake_alarm != NULL)
+			rtc->wake_alarm();
+		else
+			dev_warn(&pdev->dev,
+				 "Wake Alarm IRQ just occurred!\n");
+	}
+
+	/*
+	 * Check for a ram-clear interrupt.  This happens if RIE=1 and RF=0
+	 * when RCE=1 in 4B.  This clears all NVRAM bytes in bank0 by setting
+	 * each byte to a logic 1.  This has no effect on any extended
+	 * NV-SRAM that might be present, nor on the time/calendar/alarm
+	 * registers.  After a ram-clear is completed, there is a minimum
+	 * recovery time of ~150ms in which all reads/writes are locked out.
+	 * NOTE: A ram-clear can still occur if RCE=1 and RIE=0.  We cannot
+	 * catch this scenario.
+	 */
+	if ((ctrl4b & RTC_CTRL_4B_RIE) && (ctrl4a & RTC_CTRL_4A_RF)) {
+		rtc->write(rtc, RTC_EXT_CTRL_4A,
+			   (ctrl4a & ~(RTC_CTRL_4A_RF)));
+		msleep(150);
+
+		/* Call the platform post_ram_clear function if defined. */
+		if (rtc->post_ram_clear != NULL)
+			rtc->post_ram_clear();
+		else
+			dev_warn(&pdev->dev,
+				 "RAM-Clear IRQ just occurred!\n");
+	}
+	ds1685_rtc_switch_to_bank0(rtc);
+}
+
+/**
+ * ds1685_rtc_irq_handler - IRQ handler.
+ * @irq: IRQ number.
+ * @dev_id: platform device pointer.
+ */
+static irqreturn_t
+ds1685_rtc_irq_handler(int irq, void *dev_id)
+{
+	struct platform_device *pdev = dev_id;
+	struct ds1685_priv *rtc = platform_get_drvdata(pdev);
+	u8 ctrlb, ctrlc;
+	unsigned long events = 0;
+	u8 num_irqs = 0;
+
+	/* Abort early if the device isn't ready yet (i.e., DEBUG_SHIRQ). */
+	if (unlikely(!rtc))
+		return IRQ_HANDLED;
+
+	rtc_lock(rtc->dev);
+
+	/* Ctrlb holds the interrupt-enable bits and ctrlc the flag bits. */
+	ctrlb = rtc->read(rtc, RTC_CTRL_B);
+	ctrlc = rtc->read(rtc, RTC_CTRL_C);
+
+	/* Is the IRQF bit set? */
+	if (likely(ctrlc & RTC_CTRL_C_IRQF)) {
+		/*
+		 * We need to determine if it was one of the standard
+		 * events: PF, AF, or UF.  If so, we handle them and
+		 * update the RTC core.
+		 */
+		if (likely(ctrlc & RTC_CTRL_B_PAU_MASK)) {
+			events = RTC_IRQF;
+
+			/* Check for a periodic interrupt. */
+			if ((ctrlb & RTC_CTRL_B_PIE) &&
+			    (ctrlc & RTC_CTRL_C_PF)) {
+				events |= RTC_PF;
+				num_irqs++;
+			}
+
+			/* Check for an alarm interrupt. */
+			if ((ctrlb & RTC_CTRL_B_AIE) &&
+			    (ctrlc & RTC_CTRL_C_AF)) {
+				events |= RTC_AF;
+				num_irqs++;
+			}
+
+			/* Check for an update interrupt. */
+			if ((ctrlb & RTC_CTRL_B_UIE) &&
+			    (ctrlc & RTC_CTRL_C_UF)) {
+				events |= RTC_UF;
+				num_irqs++;
+			}
+		} else {
+			/*
+			 * One of the "extended" interrupts was received that
+			 * is not recognized by the RTC core.
+			 */
+			ds1685_rtc_extended_irq(rtc, pdev);
+		}
+	}
+	rtc_update_irq(rtc->dev, num_irqs, events);
+	rtc_unlock(rtc->dev);
+
+	return events ? IRQ_HANDLED : IRQ_NONE;
+}
+/* ----------------------------------------------------------------------- */
+
+
+/* ----------------------------------------------------------------------- */
+/* ProcFS interface */
+
+#ifdef CONFIG_PROC_FS
+#define NUM_REGS	6	/* Num of control registers. */
+#define NUM_BITS	8	/* Num bits per register. */
+#define NUM_SPACES	4	/* Num spaces between each bit. */
+
+/*
+ * Periodic Interrupt Rates.
+ */
+static const char *ds1685_rtc_pirq_rate[16] = {
+	"none", "3.90625ms", "7.8125ms", "0.122070ms", "0.244141ms",
+	"0.488281ms", "0.9765625ms", "1.953125ms", "3.90625ms", "7.8125ms",
+	"15.625ms", "31.25ms", "62.5ms", "125ms", "250ms", "500ms"
+};
+
+/*
+ * Square-Wave Output Frequencies.
+ */
+static const char *ds1685_rtc_sqw_freq[16] = {
+	"none", "256Hz", "128Hz", "8192Hz", "4096Hz", "2048Hz", "1024Hz",
+	"512Hz", "256Hz", "128Hz", "64Hz", "32Hz", "16Hz", "8Hz", "4Hz", "2Hz"
+};
+
+/**
+ * ds1685_rtc_proc - procfs access function.
+ * @dev: pointer to device structure.
+ * @seq: pointer to seq_file structure.
+ */
+static int
+ds1685_rtc_proc(struct device *dev, struct seq_file *seq)
+{
+	struct ds1685_priv *rtc = dev_get_drvdata(dev);
+	u8 ctrla, ctrlb, ctrld, ctrl4a, ctrl4b, ssn[8];
+	char *model;
+
+	/* Read all the relevant data from the control registers. */
+	ds1685_rtc_switch_to_bank1(rtc);
+	ds1685_rtc_get_ssn(rtc, ssn);
+	ctrla = rtc->read(rtc, RTC_CTRL_A);
+	ctrlb = rtc->read(rtc, RTC_CTRL_B);
+	ctrld = rtc->read(rtc, RTC_CTRL_D);
+	ctrl4a = rtc->read(rtc, RTC_EXT_CTRL_4A);
+	ctrl4b = rtc->read(rtc, RTC_EXT_CTRL_4B);
+	ds1685_rtc_switch_to_bank0(rtc);
+
+	/* Determine the RTC model. */
+	switch (ssn[0]) {
+	case RTC_MODEL_DS1685:
+		model = "DS1685/DS1687\0";
+		break;
+	case RTC_MODEL_DS1689:
+		model = "DS1689/DS1693\0";
+		break;
+	case RTC_MODEL_DS17285:
+		model = "DS17285/DS17287\0";
+		break;
+	case RTC_MODEL_DS17485:
+		model = "DS17485/DS17487\0";
+		break;
+	case RTC_MODEL_DS17885:
+		model = "DS17885/DS17887\0";
+		break;
+	default:
+		model = "Unknown\0";
+		break;
+	}
+
+	/* Print out the information. */
+	seq_printf(seq,
+	   "Model\t\t: %s\n"
+	   "Oscillator\t: %s\n"
+	   "12/24hr\t\t: %s\n"
+	   "DST\t\t: %s\n"
+	   "Data mode\t: %s\n"
+	   "Battery\t\t: %s\n"
+	   "Aux batt\t: %s\n"
+	   "Update IRQ\t: %s\n"
+	   "Periodic IRQ\t: %s\n"
+	   "Periodic Rate\t: %s\n"
+	   "SQW Freq\t: %s\n"
+	   "Serial #\t: %8phC\n",
+	   model,
+	   ((ctrla & RTC_CTRL_A_DV1) ? "enabled" : "disabled"),
+	   ((ctrlb & RTC_CTRL_B_2412) ? "24-hour" : "12-hour"),
+	   ((ctrlb & RTC_CTRL_B_DSE) ? "enabled" : "disabled"),
+	   ((ctrlb & RTC_CTRL_B_DM) ? "binary" : "BCD"),
+	   ((ctrld & RTC_CTRL_D_VRT) ? "ok" : "exhausted or n/a"),
+	   ((ctrl4a & RTC_CTRL_4A_VRT2) ? "ok" : "exhausted or n/a"),
+	   ((ctrlb & RTC_CTRL_B_UIE) ? "yes" : "no"),
+	   ((ctrlb & RTC_CTRL_B_PIE) ? "yes" : "no"),
+	   (!(ctrl4b & RTC_CTRL_4B_E32K) ?
+	    ds1685_rtc_pirq_rate[(ctrla & RTC_CTRL_A_RS_MASK)] : "none"),
+	   (!((ctrl4b & RTC_CTRL_4B_E32K)) ?
+	    ds1685_rtc_sqw_freq[(ctrla & RTC_CTRL_A_RS_MASK)] : "32768Hz"),
+	   ssn);
+	return 0;
+}
+#else
+#define ds1685_rtc_proc NULL
+#endif /* CONFIG_PROC_FS */
+/* ----------------------------------------------------------------------- */
+
+
+/* ----------------------------------------------------------------------- */
+/* RTC Class operations */
+
+static const struct rtc_class_ops
+ds1685_rtc_ops = {
+	.proc = ds1685_rtc_proc,
+	.read_time = ds1685_rtc_read_time,
+	.set_time = ds1685_rtc_set_time,
+	.read_alarm = ds1685_rtc_read_alarm,
+	.set_alarm = ds1685_rtc_set_alarm,
+	.alarm_irq_enable = ds1685_rtc_alarm_irq_enable,
+};
+/* ----------------------------------------------------------------------- */
+
+static int ds1685_nvram_read(void *priv, unsigned int pos, void *val,
+			     size_t size)
+{
+	struct ds1685_priv *rtc = priv;
+	struct mutex *rtc_mutex = &rtc->dev->ops_lock;
+	ssize_t count;
+	u8 *buf = val;
+	int err;
+
+	err = mutex_lock_interruptible(rtc_mutex);
+	if (err)
+		return err;
+
+	ds1685_rtc_switch_to_bank0(rtc);
+
+	/* Read NVRAM in time and bank0 registers. */
+	for (count = 0; size > 0 && pos < NVRAM_TOTAL_SZ_BANK0;
+	     count++, size--) {
+		if (count < NVRAM_SZ_TIME)
+			*buf++ = rtc->read(rtc, (NVRAM_TIME_BASE + pos++));
+		else
+			*buf++ = rtc->read(rtc, (NVRAM_BANK0_BASE + pos++));
+	}
+
+#ifndef CONFIG_RTC_DRV_DS1689
+	if (size > 0) {
+		ds1685_rtc_switch_to_bank1(rtc);
+
+#ifndef CONFIG_RTC_DRV_DS1685
+		/* Enable burst-mode on DS17x85/DS17x87 */
+		rtc->write(rtc, RTC_EXT_CTRL_4A,
+			   (rtc->read(rtc, RTC_EXT_CTRL_4A) |
+			    RTC_CTRL_4A_BME));
+
+		/* We need one write to RTC_BANK1_RAM_ADDR_LSB to start
+		 * reading with burst-mode */
+		rtc->write(rtc, RTC_BANK1_RAM_ADDR_LSB,
+			   (pos - NVRAM_TOTAL_SZ_BANK0));
+#endif
+
+		/* Read NVRAM in bank1 registers. */
+		for (count = 0; size > 0 && pos < NVRAM_TOTAL_SZ;
+		     count++, size--) {
+#ifdef CONFIG_RTC_DRV_DS1685
+			/* DS1685/DS1687 has to write to RTC_BANK1_RAM_ADDR
+			 * before each read. */
+			rtc->write(rtc, RTC_BANK1_RAM_ADDR,
+				   (pos - NVRAM_TOTAL_SZ_BANK0));
+#endif
+			*buf++ = rtc->read(rtc, RTC_BANK1_RAM_DATA_PORT);
+			pos++;
+		}
+
+#ifndef CONFIG_RTC_DRV_DS1685
+		/* Disable burst-mode on DS17x85/DS17x87 */
+		rtc->write(rtc, RTC_EXT_CTRL_4A,
+			   (rtc->read(rtc, RTC_EXT_CTRL_4A) &
+			    ~(RTC_CTRL_4A_BME)));
+#endif
+		ds1685_rtc_switch_to_bank0(rtc);
+	}
+#endif /* !CONFIG_RTC_DRV_DS1689 */
+	mutex_unlock(rtc_mutex);
+
+	return 0;
+}
+
+static int ds1685_nvram_write(void *priv, unsigned int pos, void *val,
+			      size_t size)
+{
+	struct ds1685_priv *rtc = priv;
+	struct mutex *rtc_mutex = &rtc->dev->ops_lock;
+	ssize_t count;
+	u8 *buf = val;
+	int err;
+
+	err = mutex_lock_interruptible(rtc_mutex);
+	if (err)
+		return err;
+
+	ds1685_rtc_switch_to_bank0(rtc);
+
+	/* Write NVRAM in time and bank0 registers. */
+	for (count = 0; size > 0 && pos < NVRAM_TOTAL_SZ_BANK0;
+	     count++, size--)
+		if (count < NVRAM_SZ_TIME)
+			rtc->write(rtc, (NVRAM_TIME_BASE + pos++),
+				   *buf++);
+		else
+			rtc->write(rtc, (NVRAM_BANK0_BASE), *buf++);
+
+#ifndef CONFIG_RTC_DRV_DS1689
+	if (size > 0) {
+		ds1685_rtc_switch_to_bank1(rtc);
+
+#ifndef CONFIG_RTC_DRV_DS1685
+		/* Enable burst-mode on DS17x85/DS17x87 */
+		rtc->write(rtc, RTC_EXT_CTRL_4A,
+			   (rtc->read(rtc, RTC_EXT_CTRL_4A) |
+			    RTC_CTRL_4A_BME));
+
+		/* We need one write to RTC_BANK1_RAM_ADDR_LSB to start
+		 * writing with burst-mode */
+		rtc->write(rtc, RTC_BANK1_RAM_ADDR_LSB,
+			   (pos - NVRAM_TOTAL_SZ_BANK0));
+#endif
+
+		/* Write NVRAM in bank1 registers. */
+		for (count = 0; size > 0 && pos < NVRAM_TOTAL_SZ;
+		     count++, size--) {
+#ifdef CONFIG_RTC_DRV_DS1685
+			/* DS1685/DS1687 has to write to RTC_BANK1_RAM_ADDR
+			 * before each read. */
+			rtc->write(rtc, RTC_BANK1_RAM_ADDR,
+				   (pos - NVRAM_TOTAL_SZ_BANK0));
+#endif
+			rtc->write(rtc, RTC_BANK1_RAM_DATA_PORT, *buf++);
+			pos++;
+		}
+
+#ifndef CONFIG_RTC_DRV_DS1685
+		/* Disable burst-mode on DS17x85/DS17x87 */
+		rtc->write(rtc, RTC_EXT_CTRL_4A,
+			   (rtc->read(rtc, RTC_EXT_CTRL_4A) &
+			    ~(RTC_CTRL_4A_BME)));
+#endif
+		ds1685_rtc_switch_to_bank0(rtc);
+	}
+#endif /* !CONFIG_RTC_DRV_DS1689 */
+	mutex_unlock(rtc_mutex);
+
+	return 0;
+}
+
+/* ----------------------------------------------------------------------- */
+/* SysFS interface */
+
+/**
+ * ds1685_rtc_sysfs_battery_show - sysfs file for main battery status.
+ * @dev: pointer to device structure.
+ * @attr: pointer to device_attribute structure.
+ * @buf: pointer to char array to hold the output.
+ */
+static ssize_t
+ds1685_rtc_sysfs_battery_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct ds1685_priv *rtc = dev_get_drvdata(dev->parent);
+	u8 ctrld;
+
+	ctrld = rtc->read(rtc, RTC_CTRL_D);
+
+	return sprintf(buf, "%s\n",
+			(ctrld & RTC_CTRL_D_VRT) ? "ok" : "not ok or N/A");
+}
+static DEVICE_ATTR(battery, S_IRUGO, ds1685_rtc_sysfs_battery_show, NULL);
+
+/**
+ * ds1685_rtc_sysfs_auxbatt_show - sysfs file for aux battery status.
+ * @dev: pointer to device structure.
+ * @attr: pointer to device_attribute structure.
+ * @buf: pointer to char array to hold the output.
+ */
+static ssize_t
+ds1685_rtc_sysfs_auxbatt_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct ds1685_priv *rtc = dev_get_drvdata(dev->parent);
+	u8 ctrl4a;
+
+	ds1685_rtc_switch_to_bank1(rtc);
+	ctrl4a = rtc->read(rtc, RTC_EXT_CTRL_4A);
+	ds1685_rtc_switch_to_bank0(rtc);
+
+	return sprintf(buf, "%s\n",
+			(ctrl4a & RTC_CTRL_4A_VRT2) ? "ok" : "not ok or N/A");
+}
+static DEVICE_ATTR(auxbatt, S_IRUGO, ds1685_rtc_sysfs_auxbatt_show, NULL);
+
+/**
+ * ds1685_rtc_sysfs_serial_show - sysfs file for silicon serial number.
+ * @dev: pointer to device structure.
+ * @attr: pointer to device_attribute structure.
+ * @buf: pointer to char array to hold the output.
+ */
+static ssize_t
+ds1685_rtc_sysfs_serial_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct ds1685_priv *rtc = dev_get_drvdata(dev->parent);
+	u8 ssn[8];
+
+	ds1685_rtc_switch_to_bank1(rtc);
+	ds1685_rtc_get_ssn(rtc, ssn);
+	ds1685_rtc_switch_to_bank0(rtc);
+
+	return sprintf(buf, "%8phC\n", ssn);
+}
+static DEVICE_ATTR(serial, S_IRUGO, ds1685_rtc_sysfs_serial_show, NULL);
+
+/*
+ * struct ds1685_rtc_sysfs_misc_attrs - list for misc RTC features.
+ */
+static struct attribute*
+ds1685_rtc_sysfs_misc_attrs[] = {
+	&dev_attr_battery.attr,
+	&dev_attr_auxbatt.attr,
+	&dev_attr_serial.attr,
+	NULL,
+};
+
+/*
+ * struct ds1685_rtc_sysfs_misc_grp - attr group for misc RTC features.
+ */
+static const struct attribute_group
+ds1685_rtc_sysfs_misc_grp = {
+	.name = "misc",
+	.attrs = ds1685_rtc_sysfs_misc_attrs,
+};
+
+/* ----------------------------------------------------------------------- */
+/* Driver Probe/Removal */
+
+/**
+ * ds1685_rtc_probe - initializes rtc driver.
+ * @pdev: pointer to platform_device structure.
+ */
+static int
+ds1685_rtc_probe(struct platform_device *pdev)
+{
+	struct rtc_device *rtc_dev;
+	struct ds1685_priv *rtc;
+	struct ds1685_rtc_platform_data *pdata;
+	u8 ctrla, ctrlb, hours;
+	unsigned char am_pm;
+	int ret = 0;
+	struct nvmem_config nvmem_cfg = {
+		.name = "ds1685_nvram",
+		.size = NVRAM_TOTAL_SZ,
+		.reg_read = ds1685_nvram_read,
+		.reg_write = ds1685_nvram_write,
+	};
+
+	/* Get the platform data. */
+	pdata = (struct ds1685_rtc_platform_data *) pdev->dev.platform_data;
+	if (!pdata)
+		return -ENODEV;
+
+	/* Allocate memory for the rtc device. */
+	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
+	if (!rtc)
+		return -ENOMEM;
+
+	/* Setup resources and access functions */
+	switch (pdata->access_type) {
+	case ds1685_reg_direct:
+		rtc->regs = devm_platform_ioremap_resource(pdev, 0);
+		if (IS_ERR(rtc->regs))
+			return PTR_ERR(rtc->regs);
+		rtc->read = ds1685_read;
+		rtc->write = ds1685_write;
+		break;
+	case ds1685_reg_indirect:
+		rtc->regs = devm_platform_ioremap_resource(pdev, 0);
+		if (IS_ERR(rtc->regs))
+			return PTR_ERR(rtc->regs);
+		rtc->data = devm_platform_ioremap_resource(pdev, 1);
+		if (IS_ERR(rtc->data))
+			return PTR_ERR(rtc->data);
+		rtc->read = ds1685_indirect_read;
+		rtc->write = ds1685_indirect_write;
+		break;
+	}
+
+	if (!rtc->read || !rtc->write)
+		return -ENXIO;
+
+	/* Get the register step size. */
+	if (pdata->regstep > 0)
+		rtc->regstep = pdata->regstep;
+	else
+		rtc->regstep = 1;
+
+	/* Platform pre-shutdown function, if defined. */
+	if (pdata->plat_prepare_poweroff)
+		rtc->prepare_poweroff = pdata->plat_prepare_poweroff;
+
+	/* Platform wake_alarm function, if defined. */
+	if (pdata->plat_wake_alarm)
+		rtc->wake_alarm = pdata->plat_wake_alarm;
+
+	/* Platform post_ram_clear function, if defined. */
+	if (pdata->plat_post_ram_clear)
+		rtc->post_ram_clear = pdata->plat_post_ram_clear;
+
+	/* set the driver data. */
+	platform_set_drvdata(pdev, rtc);
+
+	/* Turn the oscillator on if is not already on (DV1 = 1). */
+	ctrla = rtc->read(rtc, RTC_CTRL_A);
+	if (!(ctrla & RTC_CTRL_A_DV1))
+		ctrla |= RTC_CTRL_A_DV1;
+
+	/* Enable the countdown chain (DV2 = 0) */
+	ctrla &= ~(RTC_CTRL_A_DV2);
+
+	/* Clear RS3-RS0 in Control A. */
+	ctrla &= ~(RTC_CTRL_A_RS_MASK);
+
+	/*
+	 * All done with Control A.  Switch to Bank 1 for the remainder of
+	 * the RTC setup so we have access to the extended functions.
+	 */
+	ctrla |= RTC_CTRL_A_DV0;
+	rtc->write(rtc, RTC_CTRL_A, ctrla);
+
+	/* Default to 32768kHz output. */
+	rtc->write(rtc, RTC_EXT_CTRL_4B,
+		   (rtc->read(rtc, RTC_EXT_CTRL_4B) | RTC_CTRL_4B_E32K));
+
+	/* Set the SET bit in Control B so we can do some housekeeping. */
+	rtc->write(rtc, RTC_CTRL_B,
+		   (rtc->read(rtc, RTC_CTRL_B) | RTC_CTRL_B_SET));
+
+	/* Read Ext Ctrl 4A and check the INCR bit to avoid a lockout. */
+	while (rtc->read(rtc, RTC_EXT_CTRL_4A) & RTC_CTRL_4A_INCR)
+		cpu_relax();
+
+	/*
+	 * If the platform supports BCD mode, then set DM=0 in Control B.
+	 * Otherwise, set DM=1 for BIN mode.
+	 */
+	ctrlb = rtc->read(rtc, RTC_CTRL_B);
+	if (pdata->bcd_mode)
+		ctrlb &= ~(RTC_CTRL_B_DM);
+	else
+		ctrlb |= RTC_CTRL_B_DM;
+	rtc->bcd_mode = pdata->bcd_mode;
+
+	/*
+	 * Disable Daylight Savings Time (DSE = 0).
+	 * The RTC has hardcoded timezone information that is rendered
+	 * obselete.  We'll let the OS deal with DST settings instead.
+	 */
+	if (ctrlb & RTC_CTRL_B_DSE)
+		ctrlb &= ~(RTC_CTRL_B_DSE);
+
+	/* Force 24-hour mode (2412 = 1). */
+	if (!(ctrlb & RTC_CTRL_B_2412)) {
+		/* Reinitialize the time hours. */
+		hours = rtc->read(rtc, RTC_HRS);
+		am_pm = hours & RTC_HRS_AMPM_MASK;
+		hours = ds1685_rtc_bcd2bin(rtc, hours, RTC_HRS_12_BCD_MASK,
+					   RTC_HRS_12_BIN_MASK);
+		hours = ((hours == 12) ? 0 : ((am_pm) ? hours + 12 : hours));
+
+		/* Enable 24-hour mode. */
+		ctrlb |= RTC_CTRL_B_2412;
+
+		/* Write back to Control B, including DM & DSE bits. */
+		rtc->write(rtc, RTC_CTRL_B, ctrlb);
+
+		/* Write the time hours back. */
+		rtc->write(rtc, RTC_HRS,
+			   ds1685_rtc_bin2bcd(rtc, hours,
+					      RTC_HRS_24_BIN_MASK,
+					      RTC_HRS_24_BCD_MASK));
+
+		/* Reinitialize the alarm hours. */
+		hours = rtc->read(rtc, RTC_HRS_ALARM);
+		am_pm = hours & RTC_HRS_AMPM_MASK;
+		hours = ds1685_rtc_bcd2bin(rtc, hours, RTC_HRS_12_BCD_MASK,
+					   RTC_HRS_12_BIN_MASK);
+		hours = ((hours == 12) ? 0 : ((am_pm) ? hours + 12 : hours));
+
+		/* Write the alarm hours back. */
+		rtc->write(rtc, RTC_HRS_ALARM,
+			   ds1685_rtc_bin2bcd(rtc, hours,
+					      RTC_HRS_24_BIN_MASK,
+					      RTC_HRS_24_BCD_MASK));
+	} else {
+		/* 24-hour mode is already set, so write Control B back. */
+		rtc->write(rtc, RTC_CTRL_B, ctrlb);
+	}
+
+	/* Unset the SET bit in Control B so the RTC can update. */
+	rtc->write(rtc, RTC_CTRL_B,
+		   (rtc->read(rtc, RTC_CTRL_B) & ~(RTC_CTRL_B_SET)));
+
+	/* Check the main battery. */
+	if (!(rtc->read(rtc, RTC_CTRL_D) & RTC_CTRL_D_VRT))
+		dev_warn(&pdev->dev,
+			 "Main battery is exhausted! RTC may be invalid!\n");
+
+	/* Check the auxillary battery.  It is optional. */
+	if (!(rtc->read(rtc, RTC_EXT_CTRL_4A) & RTC_CTRL_4A_VRT2))
+		dev_warn(&pdev->dev,
+			 "Aux battery is exhausted or not available.\n");
+
+	/* Read Ctrl B and clear PIE/AIE/UIE. */
+	rtc->write(rtc, RTC_CTRL_B,
+		   (rtc->read(rtc, RTC_CTRL_B) & ~(RTC_CTRL_B_PAU_MASK)));
+
+	/* Reading Ctrl C auto-clears PF/AF/UF. */
+	rtc->read(rtc, RTC_CTRL_C);
+
+	/* Read Ctrl 4B and clear RIE/WIE/KSE. */
+	rtc->write(rtc, RTC_EXT_CTRL_4B,
+		   (rtc->read(rtc, RTC_EXT_CTRL_4B) & ~(RTC_CTRL_4B_RWK_MASK)));
+
+	/* Clear RF/WF/KF in Ctrl 4A. */
+	rtc->write(rtc, RTC_EXT_CTRL_4A,
+		   (rtc->read(rtc, RTC_EXT_CTRL_4A) & ~(RTC_CTRL_4A_RWK_MASK)));
+
+	/*
+	 * Re-enable KSE to handle power button events.  We do not enable
+	 * WIE or RIE by default.
+	 */
+	rtc->write(rtc, RTC_EXT_CTRL_4B,
+		   (rtc->read(rtc, RTC_EXT_CTRL_4B) | RTC_CTRL_4B_KSE));
+
+	rtc_dev = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(rtc_dev))
+		return PTR_ERR(rtc_dev);
+
+	rtc_dev->ops = &ds1685_rtc_ops;
+
+	/* Century bit is useless because leap year fails in 1900 and 2100 */
+	rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_2000;
+	rtc_dev->range_max = RTC_TIMESTAMP_END_2099;
+
+	/* See if the platform doesn't support UIE. */
+	if (pdata->uie_unsupported)
+		clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc_dev->features);
+
+	rtc->dev = rtc_dev;
+
+	/*
+	 * Fetch the IRQ and setup the interrupt handler.
+	 *
+	 * Not all platforms have the IRQF pin tied to something.  If not, the
+	 * RTC will still set the *IE / *F flags and raise IRQF in ctrlc, but
+	 * there won't be an automatic way of notifying the kernel about it,
+	 * unless ctrlc is explicitly polled.
+	 */
+	rtc->irq_num = platform_get_irq(pdev, 0);
+	if (rtc->irq_num <= 0) {
+		clear_bit(RTC_FEATURE_ALARM, rtc_dev->features);
+	} else {
+		/* Request an IRQ. */
+		ret = devm_request_threaded_irq(&pdev->dev, rtc->irq_num,
+				       NULL, ds1685_rtc_irq_handler,
+				       IRQF_SHARED | IRQF_ONESHOT,
+				       pdev->name, pdev);
+
+		/* Check to see if something came back. */
+		if (unlikely(ret)) {
+			dev_warn(&pdev->dev,
+				 "RTC interrupt not available\n");
+			rtc->irq_num = 0;
+		}
+	}
+
+	/* Setup complete. */
+	ds1685_rtc_switch_to_bank0(rtc);
+
+	ret = rtc_add_group(rtc_dev, &ds1685_rtc_sysfs_misc_grp);
+	if (ret)
+		return ret;
+
+	nvmem_cfg.priv = rtc;
+	ret = devm_rtc_nvmem_register(rtc_dev, &nvmem_cfg);
+	if (ret)
+		return ret;
+
+	return devm_rtc_register_device(rtc_dev);
+}
+
+/**
+ * ds1685_rtc_remove - removes rtc driver.
+ * @pdev: pointer to platform_device structure.
+ */
+static void
+ds1685_rtc_remove(struct platform_device *pdev)
+{
+	struct ds1685_priv *rtc = platform_get_drvdata(pdev);
+
+	/* Read Ctrl B and clear PIE/AIE/UIE. */
+	rtc->write(rtc, RTC_CTRL_B,
+		   (rtc->read(rtc, RTC_CTRL_B) &
+		    ~(RTC_CTRL_B_PAU_MASK)));
+
+	/* Reading Ctrl C auto-clears PF/AF/UF. */
+	rtc->read(rtc, RTC_CTRL_C);
+
+	/* Read Ctrl 4B and clear RIE/WIE/KSE. */
+	rtc->write(rtc, RTC_EXT_CTRL_4B,
+		   (rtc->read(rtc, RTC_EXT_CTRL_4B) &
+		    ~(RTC_CTRL_4B_RWK_MASK)));
+
+	/* Manually clear RF/WF/KF in Ctrl 4A. */
+	rtc->write(rtc, RTC_EXT_CTRL_4A,
+		   (rtc->read(rtc, RTC_EXT_CTRL_4A) &
+		    ~(RTC_CTRL_4A_RWK_MASK)));
+}
+
+/*
+ * ds1685_rtc_driver - rtc driver properties.
+ */
+static struct platform_driver ds1685_rtc_driver = {
+	.driver		= {
+		.name	= "rtc-ds1685",
+	},
+	.probe		= ds1685_rtc_probe,
+	.remove		= ds1685_rtc_remove,
+};
+module_platform_driver(ds1685_rtc_driver);
+/* ----------------------------------------------------------------------- */
+
+
+/* ----------------------------------------------------------------------- */
+/* Poweroff function */
+
+/**
+ * ds1685_rtc_poweroff - uses the RTC chip to power the system off.
+ * @pdev: pointer to platform_device structure.
+ */
+void __noreturn
+ds1685_rtc_poweroff(struct platform_device *pdev)
+{
+	u8 ctrla, ctrl4a, ctrl4b;
+	struct ds1685_priv *rtc;
+
+	/* Check for valid RTC data, else, spin forever. */
+	if (unlikely(!pdev)) {
+		pr_emerg("platform device data not available, spinning forever ...\n");
+		while(1);
+		unreachable();
+	} else {
+		/* Get the rtc data. */
+		rtc = platform_get_drvdata(pdev);
+
+		/*
+		 * Disable our IRQ.  We're powering down, so we're not
+		 * going to worry about cleaning up.  Most of that should
+		 * have been taken care of by the shutdown scripts and this
+		 * is the final function call.
+		 */
+		if (rtc->irq_num)
+			disable_irq_nosync(rtc->irq_num);
+
+		/* Oscillator must be on and the countdown chain enabled. */
+		ctrla = rtc->read(rtc, RTC_CTRL_A);
+		ctrla |= RTC_CTRL_A_DV1;
+		ctrla &= ~(RTC_CTRL_A_DV2);
+		rtc->write(rtc, RTC_CTRL_A, ctrla);
+
+		/*
+		 * Read Control 4A and check the status of the auxillary
+		 * battery.  This must be present and working (VRT2 = 1)
+		 * for wakeup and kickstart functionality to be useful.
+		 */
+		ds1685_rtc_switch_to_bank1(rtc);
+		ctrl4a = rtc->read(rtc, RTC_EXT_CTRL_4A);
+		if (ctrl4a & RTC_CTRL_4A_VRT2) {
+			/* Clear all of the interrupt flags on Control 4A. */
+			ctrl4a &= ~(RTC_CTRL_4A_RWK_MASK);
+			rtc->write(rtc, RTC_EXT_CTRL_4A, ctrl4a);
+
+			/*
+			 * The auxillary battery is present and working.
+			 * Enable extended functions (ABE=1), enable
+			 * wake-up (WIE=1), and enable kickstart (KSE=1)
+			 * in Control 4B.
+			 */
+			ctrl4b = rtc->read(rtc, RTC_EXT_CTRL_4B);
+			ctrl4b |= (RTC_CTRL_4B_ABE | RTC_CTRL_4B_WIE |
+				   RTC_CTRL_4B_KSE);
+			rtc->write(rtc, RTC_EXT_CTRL_4B, ctrl4b);
+		}
+
+		/* Set PAB to 1 in Control 4A to power the system down. */
+		dev_warn(&pdev->dev, "Powerdown.\n");
+		msleep(20);
+		rtc->write(rtc, RTC_EXT_CTRL_4A,
+			   (ctrl4a | RTC_CTRL_4A_PAB));
+
+		/* Spin ... we do not switch back to bank0. */
+		while(1);
+		unreachable();
+	}
+}
+EXPORT_SYMBOL_GPL(ds1685_rtc_poweroff);
+/* ----------------------------------------------------------------------- */
+
+
+MODULE_AUTHOR("Joshua Kinard <linux@kumba.dev>");
+MODULE_AUTHOR("Matthias Fuchs <matthias.fuchs@esd-electronics.com>");
+MODULE_DESCRIPTION("Dallas/Maxim DS1685/DS1687-series RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:rtc-ds1685");