Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

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");