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, 642 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-ac100.c b/drivers/rtc/rtc-ac100.c
new file mode 100644
index 000000000..bba7115ff
--- /dev/null
+++ b/drivers/rtc/rtc-ac100.c
@@ -0,0 +1,642 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * RTC Driver for X-Powers AC100
+ *
+ * Copyright (c) 2016 Chen-Yu Tsai
+ *
+ * Chen-Yu Tsai <wens@csie.org>
+ */
+
+#include <linux/bcd.h>
+#include <linux/clk-provider.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mfd/ac100.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/rtc.h>
+#include <linux/types.h>
+
+/* Control register */
+#define AC100_RTC_CTRL_24HOUR	BIT(0)
+
+/* Clock output register bits */
+#define AC100_CLKOUT_PRE_DIV_SHIFT	5
+#define AC100_CLKOUT_PRE_DIV_WIDTH	3
+#define AC100_CLKOUT_MUX_SHIFT		4
+#define AC100_CLKOUT_MUX_WIDTH		1
+#define AC100_CLKOUT_DIV_SHIFT		1
+#define AC100_CLKOUT_DIV_WIDTH		3
+#define AC100_CLKOUT_EN			BIT(0)
+
+/* RTC */
+#define AC100_RTC_SEC_MASK	GENMASK(6, 0)
+#define AC100_RTC_MIN_MASK	GENMASK(6, 0)
+#define AC100_RTC_HOU_MASK	GENMASK(5, 0)
+#define AC100_RTC_WEE_MASK	GENMASK(2, 0)
+#define AC100_RTC_DAY_MASK	GENMASK(5, 0)
+#define AC100_RTC_MON_MASK	GENMASK(4, 0)
+#define AC100_RTC_YEA_MASK	GENMASK(7, 0)
+#define AC100_RTC_YEA_LEAP	BIT(15)
+#define AC100_RTC_UPD_TRIGGER	BIT(15)
+
+/* Alarm (wall clock) */
+#define AC100_ALM_INT_ENABLE	BIT(0)
+
+#define AC100_ALM_SEC_MASK	GENMASK(6, 0)
+#define AC100_ALM_MIN_MASK	GENMASK(6, 0)
+#define AC100_ALM_HOU_MASK	GENMASK(5, 0)
+#define AC100_ALM_WEE_MASK	GENMASK(2, 0)
+#define AC100_ALM_DAY_MASK	GENMASK(5, 0)
+#define AC100_ALM_MON_MASK	GENMASK(4, 0)
+#define AC100_ALM_YEA_MASK	GENMASK(7, 0)
+#define AC100_ALM_ENABLE_FLAG	BIT(15)
+#define AC100_ALM_UPD_TRIGGER	BIT(15)
+
+/*
+ * The year parameter passed to the driver is usually an offset relative to
+ * the year 1900. This macro is used to convert this offset to another one
+ * relative to the minimum year allowed by the hardware.
+ *
+ * The year range is 1970 - 2069. This range is selected to match Allwinner's
+ * driver.
+ */
+#define AC100_YEAR_MIN				1970
+#define AC100_YEAR_MAX				2069
+#define AC100_YEAR_OFF				(AC100_YEAR_MIN - 1900)
+
+struct ac100_clkout {
+	struct clk_hw hw;
+	struct regmap *regmap;
+	u8 offset;
+};
+
+#define to_ac100_clkout(_hw) container_of(_hw, struct ac100_clkout, hw)
+
+#define AC100_RTC_32K_NAME	"ac100-rtc-32k"
+#define AC100_RTC_32K_RATE	32768
+#define AC100_CLKOUT_NUM	3
+
+static const char * const ac100_clkout_names[AC100_CLKOUT_NUM] = {
+	"ac100-cko1-rtc",
+	"ac100-cko2-rtc",
+	"ac100-cko3-rtc",
+};
+
+struct ac100_rtc_dev {
+	struct rtc_device *rtc;
+	struct device *dev;
+	struct regmap *regmap;
+	int irq;
+	unsigned long alarm;
+
+	struct clk_hw *rtc_32k_clk;
+	struct ac100_clkout clks[AC100_CLKOUT_NUM];
+	struct clk_hw_onecell_data *clk_data;
+};
+
+/*
+ * Clock controls for 3 clock output pins
+ */
+
+static const struct clk_div_table ac100_clkout_prediv[] = {
+	{ .val = 0, .div = 1 },
+	{ .val = 1, .div = 2 },
+	{ .val = 2, .div = 4 },
+	{ .val = 3, .div = 8 },
+	{ .val = 4, .div = 16 },
+	{ .val = 5, .div = 32 },
+	{ .val = 6, .div = 64 },
+	{ .val = 7, .div = 122 },
+	{ },
+};
+
+/* Abuse the fact that one parent is 32768 Hz, and the other is 4 MHz */
+static unsigned long ac100_clkout_recalc_rate(struct clk_hw *hw,
+					      unsigned long prate)
+{
+	struct ac100_clkout *clk = to_ac100_clkout(hw);
+	unsigned int reg, div;
+
+	regmap_read(clk->regmap, clk->offset, &reg);
+
+	/* Handle pre-divider first */
+	if (prate != AC100_RTC_32K_RATE) {
+		div = (reg >> AC100_CLKOUT_PRE_DIV_SHIFT) &
+			((1 << AC100_CLKOUT_PRE_DIV_WIDTH) - 1);
+		prate = divider_recalc_rate(hw, prate, div,
+					    ac100_clkout_prediv, 0,
+					    AC100_CLKOUT_PRE_DIV_WIDTH);
+	}
+
+	div = (reg >> AC100_CLKOUT_DIV_SHIFT) &
+		(BIT(AC100_CLKOUT_DIV_WIDTH) - 1);
+	return divider_recalc_rate(hw, prate, div, NULL,
+				   CLK_DIVIDER_POWER_OF_TWO,
+				   AC100_CLKOUT_DIV_WIDTH);
+}
+
+static int ac100_clkout_determine_rate(struct clk_hw *hw,
+				       struct clk_rate_request *req)
+{
+	int i, ret, num_parents = clk_hw_get_num_parents(hw);
+	struct clk_hw *best_parent = NULL;
+	unsigned long best = 0;
+
+	for (i = 0; i < num_parents; i++) {
+		struct clk_hw *parent = clk_hw_get_parent_by_index(hw, i);
+		unsigned long prate;
+
+		/*
+		 * The clock has two parents, one is a fixed clock which is
+		 * internally registered by the ac100 driver. The other parent
+		 * is a clock from the codec side of the chip, which we
+		 * properly declare and reference in the devicetree and is
+		 * not implemented in any driver right now.
+		 * If the clock core looks for the parent of that second
+		 * missing clock, it can't find one that is registered and
+		 * returns NULL.
+		 * So we end up in a situation where clk_hw_get_num_parents
+		 * returns the amount of clocks we can be parented to, but
+		 * clk_hw_get_parent_by_index will not return the orphan
+		 * clocks.
+		 * Thus we need to check if the parent exists before
+		 * we get the parent rate, so we could use the RTC
+		 * without waiting for the codec to be supported.
+		 */
+		if (!parent)
+			continue;
+
+		prate = clk_hw_get_rate(parent);
+
+		if (prate == AC100_RTC_32K_RATE) {
+			struct clk_rate_request div_req = *req;
+
+			div_req.best_parent_rate = prate;
+
+			ret = divider_determine_rate(hw, &div_req, NULL,
+						     AC100_CLKOUT_DIV_WIDTH,
+						     CLK_DIVIDER_POWER_OF_TWO);
+			if (ret != 0 || div_req.rate > req->rate) {
+				continue;
+			} else if (req->rate - div_req.rate < req->rate - best) {
+				best = div_req.rate;
+				best_parent = parent;
+			}
+		} else {
+			int j;
+
+			for (j = 0; ac100_clkout_prediv[j].div; j++) {
+				struct clk_rate_request div_req = *req;
+				unsigned long tmp_prate;
+
+				tmp_prate = DIV_ROUND_UP(prate, ac100_clkout_prediv[j].div);
+				div_req.best_parent_rate = tmp_prate;
+
+				ret = divider_determine_rate(hw, &div_req, NULL,
+							     AC100_CLKOUT_DIV_WIDTH,
+							     CLK_DIVIDER_POWER_OF_TWO);
+				if (ret != 0 || div_req.rate > req->rate) {
+					continue;
+				} else if (req->rate - div_req.rate < req->rate - best) {
+					best = div_req.rate;
+					best_parent = parent;
+				}
+			}
+		}
+	}
+
+	if (!best)
+		return -EINVAL;
+
+	req->best_parent_hw = best_parent;
+	req->best_parent_rate = clk_hw_get_rate(best_parent);
+	req->rate = best;
+
+	return 0;
+}
+
+static int ac100_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
+				 unsigned long prate)
+{
+	struct ac100_clkout *clk = to_ac100_clkout(hw);
+	int div = 0, pre_div = 0;
+
+	do {
+		div = divider_get_val(rate * ac100_clkout_prediv[pre_div].div,
+				      prate, NULL, AC100_CLKOUT_DIV_WIDTH,
+				      CLK_DIVIDER_POWER_OF_TWO);
+		if (div >= 0)
+			break;
+	} while (prate != AC100_RTC_32K_RATE &&
+		 ac100_clkout_prediv[++pre_div].div);
+
+	if (div < 0)
+		return div;
+
+	pre_div = ac100_clkout_prediv[pre_div].val;
+
+	regmap_update_bits(clk->regmap, clk->offset,
+			   ((1 << AC100_CLKOUT_DIV_WIDTH) - 1) << AC100_CLKOUT_DIV_SHIFT |
+			   ((1 << AC100_CLKOUT_PRE_DIV_WIDTH) - 1) << AC100_CLKOUT_PRE_DIV_SHIFT,
+			   (div - 1) << AC100_CLKOUT_DIV_SHIFT |
+			   (pre_div - 1) << AC100_CLKOUT_PRE_DIV_SHIFT);
+
+	return 0;
+}
+
+static int ac100_clkout_prepare(struct clk_hw *hw)
+{
+	struct ac100_clkout *clk = to_ac100_clkout(hw);
+
+	return regmap_update_bits(clk->regmap, clk->offset, AC100_CLKOUT_EN,
+				  AC100_CLKOUT_EN);
+}
+
+static void ac100_clkout_unprepare(struct clk_hw *hw)
+{
+	struct ac100_clkout *clk = to_ac100_clkout(hw);
+
+	regmap_update_bits(clk->regmap, clk->offset, AC100_CLKOUT_EN, 0);
+}
+
+static int ac100_clkout_is_prepared(struct clk_hw *hw)
+{
+	struct ac100_clkout *clk = to_ac100_clkout(hw);
+	unsigned int reg;
+
+	regmap_read(clk->regmap, clk->offset, &reg);
+
+	return reg & AC100_CLKOUT_EN;
+}
+
+static u8 ac100_clkout_get_parent(struct clk_hw *hw)
+{
+	struct ac100_clkout *clk = to_ac100_clkout(hw);
+	unsigned int reg;
+
+	regmap_read(clk->regmap, clk->offset, &reg);
+
+	return (reg >> AC100_CLKOUT_MUX_SHIFT) & 0x1;
+}
+
+static int ac100_clkout_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct ac100_clkout *clk = to_ac100_clkout(hw);
+
+	return regmap_update_bits(clk->regmap, clk->offset,
+				  BIT(AC100_CLKOUT_MUX_SHIFT),
+				  index ? BIT(AC100_CLKOUT_MUX_SHIFT) : 0);
+}
+
+static const struct clk_ops ac100_clkout_ops = {
+	.prepare	= ac100_clkout_prepare,
+	.unprepare	= ac100_clkout_unprepare,
+	.is_prepared	= ac100_clkout_is_prepared,
+	.recalc_rate	= ac100_clkout_recalc_rate,
+	.determine_rate	= ac100_clkout_determine_rate,
+	.get_parent	= ac100_clkout_get_parent,
+	.set_parent	= ac100_clkout_set_parent,
+	.set_rate	= ac100_clkout_set_rate,
+};
+
+static int ac100_rtc_register_clks(struct ac100_rtc_dev *chip)
+{
+	struct device_node *np = chip->dev->of_node;
+	const char *parents[2] = {AC100_RTC_32K_NAME};
+	int i, ret;
+
+	chip->clk_data = devm_kzalloc(chip->dev,
+				      struct_size(chip->clk_data, hws,
+						  AC100_CLKOUT_NUM),
+				      GFP_KERNEL);
+	if (!chip->clk_data)
+		return -ENOMEM;
+
+	chip->rtc_32k_clk = clk_hw_register_fixed_rate(chip->dev,
+						       AC100_RTC_32K_NAME,
+						       NULL, 0,
+						       AC100_RTC_32K_RATE);
+	if (IS_ERR(chip->rtc_32k_clk)) {
+		ret = PTR_ERR(chip->rtc_32k_clk);
+		dev_err(chip->dev, "Failed to register RTC-32k clock: %d\n",
+			ret);
+		return ret;
+	}
+
+	parents[1] = of_clk_get_parent_name(np, 0);
+	if (!parents[1]) {
+		dev_err(chip->dev, "Failed to get ADDA 4M clock\n");
+		return -EINVAL;
+	}
+
+	for (i = 0; i < AC100_CLKOUT_NUM; i++) {
+		struct ac100_clkout *clk = &chip->clks[i];
+		struct clk_init_data init = {
+			.name = ac100_clkout_names[i],
+			.ops = &ac100_clkout_ops,
+			.parent_names = parents,
+			.num_parents = ARRAY_SIZE(parents),
+			.flags = 0,
+		};
+
+		of_property_read_string_index(np, "clock-output-names",
+					      i, &init.name);
+		clk->regmap = chip->regmap;
+		clk->offset = AC100_CLKOUT_CTRL1 + i;
+		clk->hw.init = &init;
+
+		ret = devm_clk_hw_register(chip->dev, &clk->hw);
+		if (ret) {
+			dev_err(chip->dev, "Failed to register clk '%s': %d\n",
+				init.name, ret);
+			goto err_unregister_rtc_32k;
+		}
+
+		chip->clk_data->hws[i] = &clk->hw;
+	}
+
+	chip->clk_data->num = i;
+	ret = of_clk_add_hw_provider(np, of_clk_hw_onecell_get, chip->clk_data);
+	if (ret)
+		goto err_unregister_rtc_32k;
+
+	return 0;
+
+err_unregister_rtc_32k:
+	clk_unregister_fixed_rate(chip->rtc_32k_clk->clk);
+
+	return ret;
+}
+
+static void ac100_rtc_unregister_clks(struct ac100_rtc_dev *chip)
+{
+	of_clk_del_provider(chip->dev->of_node);
+	clk_unregister_fixed_rate(chip->rtc_32k_clk->clk);
+}
+
+/*
+ * RTC related bits
+ */
+static int ac100_rtc_get_time(struct device *dev, struct rtc_time *rtc_tm)
+{
+	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
+	struct regmap *regmap = chip->regmap;
+	u16 reg[7];
+	int ret;
+
+	ret = regmap_bulk_read(regmap, AC100_RTC_SEC, reg, 7);
+	if (ret)
+		return ret;
+
+	rtc_tm->tm_sec  = bcd2bin(reg[0] & AC100_RTC_SEC_MASK);
+	rtc_tm->tm_min  = bcd2bin(reg[1] & AC100_RTC_MIN_MASK);
+	rtc_tm->tm_hour = bcd2bin(reg[2] & AC100_RTC_HOU_MASK);
+	rtc_tm->tm_wday = bcd2bin(reg[3] & AC100_RTC_WEE_MASK);
+	rtc_tm->tm_mday = bcd2bin(reg[4] & AC100_RTC_DAY_MASK);
+	rtc_tm->tm_mon  = bcd2bin(reg[5] & AC100_RTC_MON_MASK) - 1;
+	rtc_tm->tm_year = bcd2bin(reg[6] & AC100_RTC_YEA_MASK) +
+			  AC100_YEAR_OFF;
+
+	return 0;
+}
+
+static int ac100_rtc_set_time(struct device *dev, struct rtc_time *rtc_tm)
+{
+	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
+	struct regmap *regmap = chip->regmap;
+	int year;
+	u16 reg[8];
+
+	/* our RTC has a limited year range... */
+	year = rtc_tm->tm_year - AC100_YEAR_OFF;
+	if (year < 0 || year > (AC100_YEAR_MAX - 1900)) {
+		dev_err(dev, "rtc only supports year in range %d - %d\n",
+			AC100_YEAR_MIN, AC100_YEAR_MAX);
+		return -EINVAL;
+	}
+
+	/* convert to BCD */
+	reg[0] = bin2bcd(rtc_tm->tm_sec)     & AC100_RTC_SEC_MASK;
+	reg[1] = bin2bcd(rtc_tm->tm_min)     & AC100_RTC_MIN_MASK;
+	reg[2] = bin2bcd(rtc_tm->tm_hour)    & AC100_RTC_HOU_MASK;
+	reg[3] = bin2bcd(rtc_tm->tm_wday)    & AC100_RTC_WEE_MASK;
+	reg[4] = bin2bcd(rtc_tm->tm_mday)    & AC100_RTC_DAY_MASK;
+	reg[5] = bin2bcd(rtc_tm->tm_mon + 1) & AC100_RTC_MON_MASK;
+	reg[6] = bin2bcd(year)		     & AC100_RTC_YEA_MASK;
+	/* trigger write */
+	reg[7] = AC100_RTC_UPD_TRIGGER;
+
+	/* Is it a leap year? */
+	if (is_leap_year(year + AC100_YEAR_OFF + 1900))
+		reg[6] |= AC100_RTC_YEA_LEAP;
+
+	return regmap_bulk_write(regmap, AC100_RTC_SEC, reg, 8);
+}
+
+static int ac100_rtc_alarm_irq_enable(struct device *dev, unsigned int en)
+{
+	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
+	struct regmap *regmap = chip->regmap;
+	unsigned int val;
+
+	val = en ? AC100_ALM_INT_ENABLE : 0;
+
+	return regmap_write(regmap, AC100_ALM_INT_ENA, val);
+}
+
+static int ac100_rtc_get_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
+	struct regmap *regmap = chip->regmap;
+	struct rtc_time *alrm_tm = &alrm->time;
+	u16 reg[7];
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(regmap, AC100_ALM_INT_ENA, &val);
+	if (ret)
+		return ret;
+
+	alrm->enabled = !!(val & AC100_ALM_INT_ENABLE);
+
+	ret = regmap_bulk_read(regmap, AC100_ALM_SEC, reg, 7);
+	if (ret)
+		return ret;
+
+	alrm_tm->tm_sec  = bcd2bin(reg[0] & AC100_ALM_SEC_MASK);
+	alrm_tm->tm_min  = bcd2bin(reg[1] & AC100_ALM_MIN_MASK);
+	alrm_tm->tm_hour = bcd2bin(reg[2] & AC100_ALM_HOU_MASK);
+	alrm_tm->tm_wday = bcd2bin(reg[3] & AC100_ALM_WEE_MASK);
+	alrm_tm->tm_mday = bcd2bin(reg[4] & AC100_ALM_DAY_MASK);
+	alrm_tm->tm_mon  = bcd2bin(reg[5] & AC100_ALM_MON_MASK) - 1;
+	alrm_tm->tm_year = bcd2bin(reg[6] & AC100_ALM_YEA_MASK) +
+			   AC100_YEAR_OFF;
+
+	return 0;
+}
+
+static int ac100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
+	struct regmap *regmap = chip->regmap;
+	struct rtc_time *alrm_tm = &alrm->time;
+	u16 reg[8];
+	int year;
+	int ret;
+
+	/* our alarm has a limited year range... */
+	year = alrm_tm->tm_year - AC100_YEAR_OFF;
+	if (year < 0 || year > (AC100_YEAR_MAX - 1900)) {
+		dev_err(dev, "alarm only supports year in range %d - %d\n",
+			AC100_YEAR_MIN, AC100_YEAR_MAX);
+		return -EINVAL;
+	}
+
+	/* convert to BCD */
+	reg[0] = (bin2bcd(alrm_tm->tm_sec)  & AC100_ALM_SEC_MASK) |
+			AC100_ALM_ENABLE_FLAG;
+	reg[1] = (bin2bcd(alrm_tm->tm_min)  & AC100_ALM_MIN_MASK) |
+			AC100_ALM_ENABLE_FLAG;
+	reg[2] = (bin2bcd(alrm_tm->tm_hour) & AC100_ALM_HOU_MASK) |
+			AC100_ALM_ENABLE_FLAG;
+	/* Do not enable weekday alarm */
+	reg[3] = bin2bcd(alrm_tm->tm_wday) & AC100_ALM_WEE_MASK;
+	reg[4] = (bin2bcd(alrm_tm->tm_mday) & AC100_ALM_DAY_MASK) |
+			AC100_ALM_ENABLE_FLAG;
+	reg[5] = (bin2bcd(alrm_tm->tm_mon + 1)  & AC100_ALM_MON_MASK) |
+			AC100_ALM_ENABLE_FLAG;
+	reg[6] = (bin2bcd(year) & AC100_ALM_YEA_MASK) |
+			AC100_ALM_ENABLE_FLAG;
+	/* trigger write */
+	reg[7] = AC100_ALM_UPD_TRIGGER;
+
+	ret = regmap_bulk_write(regmap, AC100_ALM_SEC, reg, 8);
+	if (ret)
+		return ret;
+
+	return ac100_rtc_alarm_irq_enable(dev, alrm->enabled);
+}
+
+static irqreturn_t ac100_rtc_irq(int irq, void *data)
+{
+	struct ac100_rtc_dev *chip = data;
+	struct regmap *regmap = chip->regmap;
+	unsigned int val = 0;
+	int ret;
+
+	rtc_lock(chip->rtc);
+
+	/* read status */
+	ret = regmap_read(regmap, AC100_ALM_INT_STA, &val);
+	if (ret)
+		goto out;
+
+	if (val & AC100_ALM_INT_ENABLE) {
+		/* signal rtc framework */
+		rtc_update_irq(chip->rtc, 1, RTC_AF | RTC_IRQF);
+
+		/* clear status */
+		ret = regmap_write(regmap, AC100_ALM_INT_STA, val);
+		if (ret)
+			goto out;
+
+		/* disable interrupt */
+		ret = ac100_rtc_alarm_irq_enable(chip->dev, 0);
+		if (ret)
+			goto out;
+	}
+
+out:
+	rtc_unlock(chip->rtc);
+	return IRQ_HANDLED;
+}
+
+static const struct rtc_class_ops ac100_rtc_ops = {
+	.read_time	  = ac100_rtc_get_time,
+	.set_time	  = ac100_rtc_set_time,
+	.read_alarm	  = ac100_rtc_get_alarm,
+	.set_alarm	  = ac100_rtc_set_alarm,
+	.alarm_irq_enable = ac100_rtc_alarm_irq_enable,
+};
+
+static int ac100_rtc_probe(struct platform_device *pdev)
+{
+	struct ac100_dev *ac100 = dev_get_drvdata(pdev->dev.parent);
+	struct ac100_rtc_dev *chip;
+	int ret;
+
+	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, chip);
+	chip->dev = &pdev->dev;
+	chip->regmap = ac100->regmap;
+
+	chip->irq = platform_get_irq(pdev, 0);
+	if (chip->irq < 0)
+		return chip->irq;
+
+	chip->rtc = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(chip->rtc))
+		return PTR_ERR(chip->rtc);
+
+	chip->rtc->ops = &ac100_rtc_ops;
+
+	ret = devm_request_threaded_irq(&pdev->dev, chip->irq, NULL,
+					ac100_rtc_irq,
+					IRQF_SHARED | IRQF_ONESHOT,
+					dev_name(&pdev->dev), chip);
+	if (ret) {
+		dev_err(&pdev->dev, "Could not request IRQ\n");
+		return ret;
+	}
+
+	/* always use 24 hour mode */
+	regmap_write_bits(chip->regmap, AC100_RTC_CTRL, AC100_RTC_CTRL_24HOUR,
+			  AC100_RTC_CTRL_24HOUR);
+
+	/* disable counter alarm interrupt */
+	regmap_write(chip->regmap, AC100_ALM_INT_ENA, 0);
+
+	/* clear counter alarm pending interrupts */
+	regmap_write(chip->regmap, AC100_ALM_INT_STA, AC100_ALM_INT_ENABLE);
+
+	ret = ac100_rtc_register_clks(chip);
+	if (ret)
+		return ret;
+
+	return devm_rtc_register_device(chip->rtc);
+}
+
+static void ac100_rtc_remove(struct platform_device *pdev)
+{
+	struct ac100_rtc_dev *chip = platform_get_drvdata(pdev);
+
+	ac100_rtc_unregister_clks(chip);
+}
+
+static const struct of_device_id ac100_rtc_match[] = {
+	{ .compatible = "x-powers,ac100-rtc" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ac100_rtc_match);
+
+static struct platform_driver ac100_rtc_driver = {
+	.probe		= ac100_rtc_probe,
+	.remove		= ac100_rtc_remove,
+	.driver		= {
+		.name		= "ac100-rtc",
+		.of_match_table	= of_match_ptr(ac100_rtc_match),
+	},
+};
+module_platform_driver(ac100_rtc_driver);
+
+MODULE_DESCRIPTION("X-Powers AC100 RTC driver");
+MODULE_AUTHOR("Chen-Yu Tsai <wens@csie.org>");
+MODULE_LICENSE("GPL v2");