kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 891 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-max77686.c b/drivers/rtc/rtc-max77686.c
new file mode 100644
index 000000000..375565a3b
--- /dev/null
+++ b/drivers/rtc/rtc-max77686.c
@@ -0,0 +1,891 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// RTC driver for Maxim MAX77686 and MAX77802
+//
+// Copyright (C) 2012 Samsung Electronics Co.Ltd
+//
+//  based on rtc-max8997.c
+
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/rtc.h>
+#include <linux/delay.h>
+#include <linux/mutex.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/max77686-private.h>
+#include <linux/irqdomain.h>
+#include <linux/regmap.h>
+
+#define MAX77686_I2C_ADDR_RTC		(0x0C >> 1)
+#define MAX77620_I2C_ADDR_RTC		0x68
+#define MAX77714_I2C_ADDR_RTC		0x48
+#define MAX77686_INVALID_I2C_ADDR	(-1)
+
+/* Define non existing register */
+#define MAX77686_INVALID_REG		(-1)
+
+/* RTC Control Register */
+#define BCD_EN_SHIFT			0
+#define BCD_EN_MASK			BIT(BCD_EN_SHIFT)
+#define MODEL24_SHIFT			1
+#define MODEL24_MASK			BIT(MODEL24_SHIFT)
+/* RTC Update Register1 */
+#define RTC_UDR_SHIFT			0
+#define RTC_UDR_MASK			BIT(RTC_UDR_SHIFT)
+#define RTC_RBUDR_SHIFT			4
+#define RTC_RBUDR_MASK			BIT(RTC_RBUDR_SHIFT)
+/* RTC Alarm Enable */
+#define ALARM_ENABLE_SHIFT		7
+#define ALARM_ENABLE_MASK		BIT(ALARM_ENABLE_SHIFT)
+
+#define REG_RTC_NONE			0xdeadbeef
+
+/*
+ * MAX77802 has separate register (RTCAE1) for alarm enable instead
+ * using 1 bit from registers RTC{SEC,MIN,HOUR,DAY,MONTH,YEAR,DATE}
+ * as in done in MAX77686.
+ */
+#define MAX77802_ALARM_ENABLE_VALUE	0x77
+
+enum {
+	RTC_SEC = 0,
+	RTC_MIN,
+	RTC_HOUR,
+	RTC_WEEKDAY,
+	RTC_MONTH,
+	RTC_YEAR,
+	RTC_MONTHDAY,
+	RTC_NR_TIME
+};
+
+/**
+ * struct max77686_rtc_driver_data - model-specific configuration
+ * @delay: Minimum usecs needed for a RTC update
+ * @mask: Mask used to read RTC registers value
+ * @map: Registers offset to I2C addresses map
+ * @alarm_enable_reg: Has a separate alarm enable register?
+ * @rtc_i2c_addr: I2C address for RTC block
+ * @rtc_irq_from_platform: RTC interrupt via platform resource
+ * @alarm_pending_status_reg: Pending alarm status register
+ * @rtc_irq_chip: RTC IRQ CHIP for regmap
+ * @regmap_config: regmap configuration for the chip
+ */
+struct max77686_rtc_driver_data {
+	unsigned long		delay;
+	u8			mask;
+	const unsigned int	*map;
+	bool			alarm_enable_reg;
+	int			rtc_i2c_addr;
+	bool			rtc_irq_from_platform;
+	int			alarm_pending_status_reg;
+	const struct regmap_irq_chip *rtc_irq_chip;
+	const struct regmap_config *regmap_config;
+};
+
+struct max77686_rtc_info {
+	struct device		*dev;
+	struct rtc_device	*rtc_dev;
+	struct mutex		lock;
+
+	struct regmap		*regmap;
+	struct regmap		*rtc_regmap;
+
+	const struct max77686_rtc_driver_data *drv_data;
+	struct regmap_irq_chip_data *rtc_irq_data;
+
+	int rtc_irq;
+	int virq;
+};
+
+enum MAX77686_RTC_OP {
+	MAX77686_RTC_WRITE,
+	MAX77686_RTC_READ,
+};
+
+/* These are not registers but just offsets that are mapped to addresses */
+enum max77686_rtc_reg_offset {
+	REG_RTC_CONTROLM = 0,
+	REG_RTC_CONTROL,
+	REG_RTC_UPDATE0,
+	REG_WTSR_SMPL_CNTL,
+	REG_RTC_SEC,
+	REG_RTC_MIN,
+	REG_RTC_HOUR,
+	REG_RTC_WEEKDAY,
+	REG_RTC_MONTH,
+	REG_RTC_YEAR,
+	REG_RTC_MONTHDAY,
+	REG_ALARM1_SEC,
+	REG_ALARM1_MIN,
+	REG_ALARM1_HOUR,
+	REG_ALARM1_WEEKDAY,
+	REG_ALARM1_MONTH,
+	REG_ALARM1_YEAR,
+	REG_ALARM1_DATE,
+	REG_ALARM2_SEC,
+	REG_ALARM2_MIN,
+	REG_ALARM2_HOUR,
+	REG_ALARM2_WEEKDAY,
+	REG_ALARM2_MONTH,
+	REG_ALARM2_YEAR,
+	REG_ALARM2_DATE,
+	REG_RTC_AE1,
+	REG_RTC_END,
+};
+
+/* Maps RTC registers offset to the MAX77686 register addresses */
+static const unsigned int max77686_map[REG_RTC_END] = {
+	[REG_RTC_CONTROLM]   = MAX77686_RTC_CONTROLM,
+	[REG_RTC_CONTROL]    = MAX77686_RTC_CONTROL,
+	[REG_RTC_UPDATE0]    = MAX77686_RTC_UPDATE0,
+	[REG_WTSR_SMPL_CNTL] = MAX77686_WTSR_SMPL_CNTL,
+	[REG_RTC_SEC]        = MAX77686_RTC_SEC,
+	[REG_RTC_MIN]        = MAX77686_RTC_MIN,
+	[REG_RTC_HOUR]       = MAX77686_RTC_HOUR,
+	[REG_RTC_WEEKDAY]    = MAX77686_RTC_WEEKDAY,
+	[REG_RTC_MONTH]      = MAX77686_RTC_MONTH,
+	[REG_RTC_YEAR]       = MAX77686_RTC_YEAR,
+	[REG_RTC_MONTHDAY]   = MAX77686_RTC_MONTHDAY,
+	[REG_ALARM1_SEC]     = MAX77686_ALARM1_SEC,
+	[REG_ALARM1_MIN]     = MAX77686_ALARM1_MIN,
+	[REG_ALARM1_HOUR]    = MAX77686_ALARM1_HOUR,
+	[REG_ALARM1_WEEKDAY] = MAX77686_ALARM1_WEEKDAY,
+	[REG_ALARM1_MONTH]   = MAX77686_ALARM1_MONTH,
+	[REG_ALARM1_YEAR]    = MAX77686_ALARM1_YEAR,
+	[REG_ALARM1_DATE]    = MAX77686_ALARM1_DATE,
+	[REG_ALARM2_SEC]     = MAX77686_ALARM2_SEC,
+	[REG_ALARM2_MIN]     = MAX77686_ALARM2_MIN,
+	[REG_ALARM2_HOUR]    = MAX77686_ALARM2_HOUR,
+	[REG_ALARM2_WEEKDAY] = MAX77686_ALARM2_WEEKDAY,
+	[REG_ALARM2_MONTH]   = MAX77686_ALARM2_MONTH,
+	[REG_ALARM2_YEAR]    = MAX77686_ALARM2_YEAR,
+	[REG_ALARM2_DATE]    = MAX77686_ALARM2_DATE,
+	[REG_RTC_AE1]	     = REG_RTC_NONE,
+};
+
+static const struct regmap_irq max77686_rtc_irqs[] = {
+	/* RTC interrupts */
+	REGMAP_IRQ_REG(0, 0, MAX77686_RTCINT_RTC60S_MSK),
+	REGMAP_IRQ_REG(1, 0, MAX77686_RTCINT_RTCA1_MSK),
+	REGMAP_IRQ_REG(2, 0, MAX77686_RTCINT_RTCA2_MSK),
+	REGMAP_IRQ_REG(3, 0, MAX77686_RTCINT_SMPL_MSK),
+	REGMAP_IRQ_REG(4, 0, MAX77686_RTCINT_RTC1S_MSK),
+	REGMAP_IRQ_REG(5, 0, MAX77686_RTCINT_WTSR_MSK),
+};
+
+static const struct regmap_irq_chip max77686_rtc_irq_chip = {
+	.name		= "max77686-rtc",
+	.status_base	= MAX77686_RTC_INT,
+	.mask_base	= MAX77686_RTC_INTM,
+	.num_regs	= 1,
+	.irqs		= max77686_rtc_irqs,
+	.num_irqs	= ARRAY_SIZE(max77686_rtc_irqs),
+};
+
+static const struct regmap_config max77686_rtc_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static const struct max77686_rtc_driver_data max77686_drv_data = {
+	.delay = 16000,
+	.mask  = 0x7f,
+	.map   = max77686_map,
+	.alarm_enable_reg  = false,
+	.rtc_irq_from_platform = false,
+	.alarm_pending_status_reg = MAX77686_REG_STATUS2,
+	.rtc_i2c_addr = MAX77686_I2C_ADDR_RTC,
+	.rtc_irq_chip = &max77686_rtc_irq_chip,
+	.regmap_config = &max77686_rtc_regmap_config,
+};
+
+static const struct regmap_irq_chip max77714_rtc_irq_chip = {
+	.name		= "max77714-rtc",
+	.status_base	= MAX77686_RTC_INT,
+	.mask_base	= MAX77686_RTC_INTM,
+	.num_regs	= 1,
+	.irqs		= max77686_rtc_irqs,
+	.num_irqs	= ARRAY_SIZE(max77686_rtc_irqs) - 1, /* no WTSR on 77714 */
+};
+
+static const struct max77686_rtc_driver_data max77714_drv_data = {
+	.delay = 16000,
+	.mask  = 0x7f,
+	.map   = max77686_map,
+	.alarm_enable_reg = false,
+	.rtc_irq_from_platform = false,
+	/* On MAX77714 RTCA1 is BIT 1 of RTCINT (0x00). Not supported by this driver. */
+	.alarm_pending_status_reg = MAX77686_INVALID_REG,
+	.rtc_i2c_addr = MAX77714_I2C_ADDR_RTC,
+	.rtc_irq_chip = &max77714_rtc_irq_chip,
+	.regmap_config = &max77686_rtc_regmap_config,
+};
+
+static const struct regmap_config max77620_rtc_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.use_single_write = true,
+};
+
+static const struct max77686_rtc_driver_data max77620_drv_data = {
+	.delay = 16000,
+	.mask  = 0x7f,
+	.map   = max77686_map,
+	.alarm_enable_reg  = false,
+	.rtc_irq_from_platform = true,
+	.alarm_pending_status_reg = MAX77686_INVALID_REG,
+	.rtc_i2c_addr = MAX77620_I2C_ADDR_RTC,
+	.rtc_irq_chip = &max77686_rtc_irq_chip,
+	.regmap_config = &max77620_rtc_regmap_config,
+};
+
+static const unsigned int max77802_map[REG_RTC_END] = {
+	[REG_RTC_CONTROLM]   = MAX77802_RTC_CONTROLM,
+	[REG_RTC_CONTROL]    = MAX77802_RTC_CONTROL,
+	[REG_RTC_UPDATE0]    = MAX77802_RTC_UPDATE0,
+	[REG_WTSR_SMPL_CNTL] = MAX77802_WTSR_SMPL_CNTL,
+	[REG_RTC_SEC]        = MAX77802_RTC_SEC,
+	[REG_RTC_MIN]        = MAX77802_RTC_MIN,
+	[REG_RTC_HOUR]       = MAX77802_RTC_HOUR,
+	[REG_RTC_WEEKDAY]    = MAX77802_RTC_WEEKDAY,
+	[REG_RTC_MONTH]      = MAX77802_RTC_MONTH,
+	[REG_RTC_YEAR]       = MAX77802_RTC_YEAR,
+	[REG_RTC_MONTHDAY]   = MAX77802_RTC_MONTHDAY,
+	[REG_ALARM1_SEC]     = MAX77802_ALARM1_SEC,
+	[REG_ALARM1_MIN]     = MAX77802_ALARM1_MIN,
+	[REG_ALARM1_HOUR]    = MAX77802_ALARM1_HOUR,
+	[REG_ALARM1_WEEKDAY] = MAX77802_ALARM1_WEEKDAY,
+	[REG_ALARM1_MONTH]   = MAX77802_ALARM1_MONTH,
+	[REG_ALARM1_YEAR]    = MAX77802_ALARM1_YEAR,
+	[REG_ALARM1_DATE]    = MAX77802_ALARM1_DATE,
+	[REG_ALARM2_SEC]     = MAX77802_ALARM2_SEC,
+	[REG_ALARM2_MIN]     = MAX77802_ALARM2_MIN,
+	[REG_ALARM2_HOUR]    = MAX77802_ALARM2_HOUR,
+	[REG_ALARM2_WEEKDAY] = MAX77802_ALARM2_WEEKDAY,
+	[REG_ALARM2_MONTH]   = MAX77802_ALARM2_MONTH,
+	[REG_ALARM2_YEAR]    = MAX77802_ALARM2_YEAR,
+	[REG_ALARM2_DATE]    = MAX77802_ALARM2_DATE,
+	[REG_RTC_AE1]	     = MAX77802_RTC_AE1,
+};
+
+static const struct regmap_irq_chip max77802_rtc_irq_chip = {
+	.name		= "max77802-rtc",
+	.status_base	= MAX77802_RTC_INT,
+	.mask_base	= MAX77802_RTC_INTM,
+	.num_regs	= 1,
+	.irqs		= max77686_rtc_irqs, /* same masks as 77686 */
+	.num_irqs	= ARRAY_SIZE(max77686_rtc_irqs),
+};
+
+static const struct max77686_rtc_driver_data max77802_drv_data = {
+	.delay = 200,
+	.mask  = 0xff,
+	.map   = max77802_map,
+	.alarm_enable_reg  = true,
+	.rtc_irq_from_platform = false,
+	.alarm_pending_status_reg = MAX77686_REG_STATUS2,
+	.rtc_i2c_addr = MAX77686_INVALID_I2C_ADDR,
+	.rtc_irq_chip = &max77802_rtc_irq_chip,
+};
+
+static void max77686_rtc_data_to_tm(u8 *data, struct rtc_time *tm,
+				    struct max77686_rtc_info *info)
+{
+	u8 mask = info->drv_data->mask;
+
+	tm->tm_sec = data[RTC_SEC] & mask;
+	tm->tm_min = data[RTC_MIN] & mask;
+	tm->tm_hour = data[RTC_HOUR] & 0x1f;
+
+	/* Only a single bit is set in data[], so fls() would be equivalent */
+	tm->tm_wday = ffs(data[RTC_WEEKDAY] & mask) - 1;
+	tm->tm_mday = data[RTC_MONTHDAY] & 0x1f;
+	tm->tm_mon = (data[RTC_MONTH] & 0x0f) - 1;
+	tm->tm_year = data[RTC_YEAR] & mask;
+	tm->tm_yday = 0;
+	tm->tm_isdst = 0;
+
+	/*
+	 * MAX77686 uses 1 bit from sec/min/hour/etc RTC registers and the
+	 * year values are just 0..99 so add 100 to support up to 2099.
+	 */
+	if (!info->drv_data->alarm_enable_reg)
+		tm->tm_year += 100;
+}
+
+static int max77686_rtc_tm_to_data(struct rtc_time *tm, u8 *data,
+				   struct max77686_rtc_info *info)
+{
+	data[RTC_SEC] = tm->tm_sec;
+	data[RTC_MIN] = tm->tm_min;
+	data[RTC_HOUR] = tm->tm_hour;
+	data[RTC_WEEKDAY] = 1 << tm->tm_wday;
+	data[RTC_MONTHDAY] = tm->tm_mday;
+	data[RTC_MONTH] = tm->tm_mon + 1;
+
+	if (info->drv_data->alarm_enable_reg) {
+		data[RTC_YEAR] = tm->tm_year;
+		return 0;
+	}
+
+	data[RTC_YEAR] = tm->tm_year > 100 ? (tm->tm_year - 100) : 0;
+
+	if (tm->tm_year < 100) {
+		dev_err(info->dev, "RTC cannot handle the year %d.\n",
+			1900 + tm->tm_year);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int max77686_rtc_update(struct max77686_rtc_info *info,
+			       enum MAX77686_RTC_OP op)
+{
+	int ret;
+	unsigned int data;
+	unsigned long delay = info->drv_data->delay;
+
+	if (op == MAX77686_RTC_WRITE)
+		data = 1 << RTC_UDR_SHIFT;
+	else
+		data = 1 << RTC_RBUDR_SHIFT;
+
+	ret = regmap_update_bits(info->rtc_regmap,
+				 info->drv_data->map[REG_RTC_UPDATE0],
+				 data, data);
+	if (ret < 0)
+		dev_err(info->dev, "Fail to write update reg(ret=%d, data=0x%x)\n",
+			ret, data);
+	else {
+		/* Minimum delay required before RTC update. */
+		usleep_range(delay, delay * 2);
+	}
+
+	return ret;
+}
+
+static int max77686_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct max77686_rtc_info *info = dev_get_drvdata(dev);
+	u8 data[RTC_NR_TIME];
+	int ret;
+
+	mutex_lock(&info->lock);
+
+	ret = max77686_rtc_update(info, MAX77686_RTC_READ);
+	if (ret < 0)
+		goto out;
+
+	ret = regmap_bulk_read(info->rtc_regmap,
+			       info->drv_data->map[REG_RTC_SEC],
+			       data, ARRAY_SIZE(data));
+	if (ret < 0) {
+		dev_err(info->dev, "Fail to read time reg(%d)\n", ret);
+		goto out;
+	}
+
+	max77686_rtc_data_to_tm(data, tm, info);
+
+out:
+	mutex_unlock(&info->lock);
+	return ret;
+}
+
+static int max77686_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct max77686_rtc_info *info = dev_get_drvdata(dev);
+	u8 data[RTC_NR_TIME];
+	int ret;
+
+	ret = max77686_rtc_tm_to_data(tm, data, info);
+	if (ret < 0)
+		return ret;
+
+	mutex_lock(&info->lock);
+
+	ret = regmap_bulk_write(info->rtc_regmap,
+				info->drv_data->map[REG_RTC_SEC],
+				data, ARRAY_SIZE(data));
+	if (ret < 0) {
+		dev_err(info->dev, "Fail to write time reg(%d)\n", ret);
+		goto out;
+	}
+
+	ret = max77686_rtc_update(info, MAX77686_RTC_WRITE);
+
+out:
+	mutex_unlock(&info->lock);
+	return ret;
+}
+
+static int max77686_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct max77686_rtc_info *info = dev_get_drvdata(dev);
+	u8 data[RTC_NR_TIME];
+	unsigned int val;
+	const unsigned int *map = info->drv_data->map;
+	int i, ret;
+
+	mutex_lock(&info->lock);
+
+	ret = max77686_rtc_update(info, MAX77686_RTC_READ);
+	if (ret < 0)
+		goto out;
+
+	ret = regmap_bulk_read(info->rtc_regmap, map[REG_ALARM1_SEC],
+			       data, ARRAY_SIZE(data));
+	if (ret < 0) {
+		dev_err(info->dev, "Fail to read alarm reg(%d)\n", ret);
+		goto out;
+	}
+
+	max77686_rtc_data_to_tm(data, &alrm->time, info);
+
+	alrm->enabled = 0;
+
+	if (info->drv_data->alarm_enable_reg) {
+		if (map[REG_RTC_AE1] == REG_RTC_NONE) {
+			ret = -EINVAL;
+			dev_err(info->dev,
+				"alarm enable register not set(%d)\n", ret);
+			goto out;
+		}
+
+		ret = regmap_read(info->rtc_regmap, map[REG_RTC_AE1], &val);
+		if (ret < 0) {
+			dev_err(info->dev,
+				"fail to read alarm enable(%d)\n", ret);
+			goto out;
+		}
+
+		if (val)
+			alrm->enabled = 1;
+	} else {
+		for (i = 0; i < ARRAY_SIZE(data); i++) {
+			if (data[i] & ALARM_ENABLE_MASK) {
+				alrm->enabled = 1;
+				break;
+			}
+		}
+	}
+
+	alrm->pending = 0;
+
+	if (info->drv_data->alarm_pending_status_reg == MAX77686_INVALID_REG)
+		goto out;
+
+	ret = regmap_read(info->regmap,
+			  info->drv_data->alarm_pending_status_reg, &val);
+	if (ret < 0) {
+		dev_err(info->dev,
+			"Fail to read alarm pending status reg(%d)\n", ret);
+		goto out;
+	}
+
+	if (val & (1 << 4)) /* RTCA1 */
+		alrm->pending = 1;
+
+out:
+	mutex_unlock(&info->lock);
+	return ret;
+}
+
+static int max77686_rtc_stop_alarm(struct max77686_rtc_info *info)
+{
+	u8 data[RTC_NR_TIME];
+	int ret, i;
+	struct rtc_time tm;
+	const unsigned int *map = info->drv_data->map;
+
+	if (!mutex_is_locked(&info->lock))
+		dev_warn(info->dev, "%s: should have mutex locked\n", __func__);
+
+	ret = max77686_rtc_update(info, MAX77686_RTC_READ);
+	if (ret < 0)
+		goto out;
+
+	if (info->drv_data->alarm_enable_reg) {
+		if (map[REG_RTC_AE1] == REG_RTC_NONE) {
+			ret = -EINVAL;
+			dev_err(info->dev,
+				"alarm enable register not set(%d)\n", ret);
+			goto out;
+		}
+
+		ret = regmap_write(info->rtc_regmap, map[REG_RTC_AE1], 0);
+	} else {
+		ret = regmap_bulk_read(info->rtc_regmap, map[REG_ALARM1_SEC],
+				       data, ARRAY_SIZE(data));
+		if (ret < 0) {
+			dev_err(info->dev, "Fail to read alarm reg(%d)\n", ret);
+			goto out;
+		}
+
+		max77686_rtc_data_to_tm(data, &tm, info);
+
+		for (i = 0; i < ARRAY_SIZE(data); i++)
+			data[i] &= ~ALARM_ENABLE_MASK;
+
+		ret = regmap_bulk_write(info->rtc_regmap, map[REG_ALARM1_SEC],
+					data, ARRAY_SIZE(data));
+	}
+
+	if (ret < 0) {
+		dev_err(info->dev, "Fail to write alarm reg(%d)\n", ret);
+		goto out;
+	}
+
+	ret = max77686_rtc_update(info, MAX77686_RTC_WRITE);
+out:
+	return ret;
+}
+
+static int max77686_rtc_start_alarm(struct max77686_rtc_info *info)
+{
+	u8 data[RTC_NR_TIME];
+	int ret;
+	struct rtc_time tm;
+	const unsigned int *map = info->drv_data->map;
+
+	if (!mutex_is_locked(&info->lock))
+		dev_warn(info->dev, "%s: should have mutex locked\n", __func__);
+
+	ret = max77686_rtc_update(info, MAX77686_RTC_READ);
+	if (ret < 0)
+		goto out;
+
+	if (info->drv_data->alarm_enable_reg) {
+		ret = regmap_write(info->rtc_regmap, map[REG_RTC_AE1],
+				   MAX77802_ALARM_ENABLE_VALUE);
+	} else {
+		ret = regmap_bulk_read(info->rtc_regmap, map[REG_ALARM1_SEC],
+				       data, ARRAY_SIZE(data));
+		if (ret < 0) {
+			dev_err(info->dev, "Fail to read alarm reg(%d)\n", ret);
+			goto out;
+		}
+
+		max77686_rtc_data_to_tm(data, &tm, info);
+
+		data[RTC_SEC] |= (1 << ALARM_ENABLE_SHIFT);
+		data[RTC_MIN] |= (1 << ALARM_ENABLE_SHIFT);
+		data[RTC_HOUR] |= (1 << ALARM_ENABLE_SHIFT);
+		data[RTC_WEEKDAY] &= ~ALARM_ENABLE_MASK;
+		if (data[RTC_MONTH] & 0xf)
+			data[RTC_MONTH] |= (1 << ALARM_ENABLE_SHIFT);
+		if (data[RTC_YEAR] & info->drv_data->mask)
+			data[RTC_YEAR] |= (1 << ALARM_ENABLE_SHIFT);
+		if (data[RTC_MONTHDAY] & 0x1f)
+			data[RTC_MONTHDAY] |= (1 << ALARM_ENABLE_SHIFT);
+
+		ret = regmap_bulk_write(info->rtc_regmap, map[REG_ALARM1_SEC],
+					data, ARRAY_SIZE(data));
+	}
+
+	if (ret < 0) {
+		dev_err(info->dev, "Fail to write alarm reg(%d)\n", ret);
+		goto out;
+	}
+
+	ret = max77686_rtc_update(info, MAX77686_RTC_WRITE);
+out:
+	return ret;
+}
+
+static int max77686_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct max77686_rtc_info *info = dev_get_drvdata(dev);
+	u8 data[RTC_NR_TIME];
+	int ret;
+
+	ret = max77686_rtc_tm_to_data(&alrm->time, data, info);
+	if (ret < 0)
+		return ret;
+
+	mutex_lock(&info->lock);
+
+	ret = max77686_rtc_stop_alarm(info);
+	if (ret < 0)
+		goto out;
+
+	ret = regmap_bulk_write(info->rtc_regmap,
+				info->drv_data->map[REG_ALARM1_SEC],
+				data, ARRAY_SIZE(data));
+
+	if (ret < 0) {
+		dev_err(info->dev, "Fail to write alarm reg(%d)\n", ret);
+		goto out;
+	}
+
+	ret = max77686_rtc_update(info, MAX77686_RTC_WRITE);
+	if (ret < 0)
+		goto out;
+
+	if (alrm->enabled)
+		ret = max77686_rtc_start_alarm(info);
+out:
+	mutex_unlock(&info->lock);
+	return ret;
+}
+
+static int max77686_rtc_alarm_irq_enable(struct device *dev,
+					 unsigned int enabled)
+{
+	struct max77686_rtc_info *info = dev_get_drvdata(dev);
+	int ret;
+
+	mutex_lock(&info->lock);
+	if (enabled)
+		ret = max77686_rtc_start_alarm(info);
+	else
+		ret = max77686_rtc_stop_alarm(info);
+	mutex_unlock(&info->lock);
+
+	return ret;
+}
+
+static irqreturn_t max77686_rtc_alarm_irq(int irq, void *data)
+{
+	struct max77686_rtc_info *info = data;
+
+	dev_dbg(info->dev, "RTC alarm IRQ: %d\n", irq);
+
+	rtc_update_irq(info->rtc_dev, 1, RTC_IRQF | RTC_AF);
+
+	return IRQ_HANDLED;
+}
+
+static const struct rtc_class_ops max77686_rtc_ops = {
+	.read_time = max77686_rtc_read_time,
+	.set_time = max77686_rtc_set_time,
+	.read_alarm = max77686_rtc_read_alarm,
+	.set_alarm = max77686_rtc_set_alarm,
+	.alarm_irq_enable = max77686_rtc_alarm_irq_enable,
+};
+
+static int max77686_rtc_init_reg(struct max77686_rtc_info *info)
+{
+	u8 data[2];
+	int ret;
+
+	/* Set RTC control register : Binary mode, 24hour mdoe */
+	data[0] = (1 << BCD_EN_SHIFT) | (1 << MODEL24_SHIFT);
+	data[1] = (0 << BCD_EN_SHIFT) | (1 << MODEL24_SHIFT);
+
+	ret = regmap_bulk_write(info->rtc_regmap,
+				info->drv_data->map[REG_RTC_CONTROLM],
+				data, ARRAY_SIZE(data));
+	if (ret < 0) {
+		dev_err(info->dev, "Fail to write controlm reg(%d)\n", ret);
+		return ret;
+	}
+
+	ret = max77686_rtc_update(info, MAX77686_RTC_WRITE);
+	return ret;
+}
+
+static void max77686_rtc_release_dev(void *client)
+{
+	i2c_unregister_device(client);
+}
+
+static int max77686_init_rtc_regmap(struct max77686_rtc_info *info)
+{
+	struct device *parent = info->dev->parent;
+	struct i2c_client *parent_i2c = to_i2c_client(parent);
+	struct i2c_client *client;
+	int ret;
+
+	if (info->drv_data->rtc_irq_from_platform) {
+		struct platform_device *pdev = to_platform_device(info->dev);
+
+		info->rtc_irq = platform_get_irq(pdev, 0);
+		if (info->rtc_irq < 0)
+			return info->rtc_irq;
+	} else {
+		info->rtc_irq =  parent_i2c->irq;
+	}
+
+	info->regmap = dev_get_regmap(parent, NULL);
+	if (!info->regmap)
+		return dev_err_probe(info->dev, -ENODEV,
+				     "Failed to get rtc regmap\n");
+
+	if (info->drv_data->rtc_i2c_addr == MAX77686_INVALID_I2C_ADDR) {
+		info->rtc_regmap = info->regmap;
+		goto add_rtc_irq;
+	}
+
+	client = i2c_new_ancillary_device(parent_i2c, "rtc",
+					  info->drv_data->rtc_i2c_addr);
+	if (IS_ERR(client))
+		return dev_err_probe(info->dev, PTR_ERR(client),
+				     "Failed to allocate I2C device for RTC\n");
+
+	ret = devm_add_action_or_reset(info->dev, max77686_rtc_release_dev,
+				       client);
+	if (ret)
+		return ret;
+
+	info->rtc_regmap = devm_regmap_init_i2c(client,
+						info->drv_data->regmap_config);
+	if (IS_ERR(info->rtc_regmap))
+		return dev_err_probe(info->dev, PTR_ERR(info->rtc_regmap),
+				     "Failed to allocate RTC regmap\n");
+
+add_rtc_irq:
+	ret = regmap_add_irq_chip(info->rtc_regmap, info->rtc_irq,
+				  IRQF_ONESHOT | IRQF_SHARED,
+				  0, info->drv_data->rtc_irq_chip,
+				  &info->rtc_irq_data);
+	if (ret < 0)
+		return dev_err_probe(info->dev, ret,
+				     "Failed to add RTC irq chip\n");
+
+	return 0;
+}
+
+static int max77686_rtc_probe(struct platform_device *pdev)
+{
+	struct max77686_rtc_info *info;
+	const struct platform_device_id *id = platform_get_device_id(pdev);
+	int ret;
+
+	info = devm_kzalloc(&pdev->dev, sizeof(struct max77686_rtc_info),
+			    GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	mutex_init(&info->lock);
+	info->dev = &pdev->dev;
+	info->drv_data = (const struct max77686_rtc_driver_data *)
+		id->driver_data;
+
+	ret = max77686_init_rtc_regmap(info);
+	if (ret < 0)
+		return ret;
+
+	platform_set_drvdata(pdev, info);
+
+	ret = max77686_rtc_init_reg(info);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to initialize RTC reg:%d\n", ret);
+		goto err_rtc;
+	}
+
+	device_init_wakeup(&pdev->dev, true);
+
+	info->rtc_dev = devm_rtc_device_register(&pdev->dev, id->name,
+					&max77686_rtc_ops, THIS_MODULE);
+
+	if (IS_ERR(info->rtc_dev)) {
+		ret = PTR_ERR(info->rtc_dev);
+		dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
+		if (ret == 0)
+			ret = -EINVAL;
+		goto err_rtc;
+	}
+
+	info->virq = regmap_irq_get_virq(info->rtc_irq_data,
+					 MAX77686_RTCIRQ_RTCA1);
+	if (info->virq <= 0) {
+		ret = -ENXIO;
+		goto err_rtc;
+	}
+
+	ret = request_threaded_irq(info->virq, NULL, max77686_rtc_alarm_irq, 0,
+				   "rtc-alarm1", info);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to request alarm IRQ: %d: %d\n",
+			info->virq, ret);
+		goto err_rtc;
+	}
+
+	return 0;
+
+err_rtc:
+	regmap_del_irq_chip(info->rtc_irq, info->rtc_irq_data);
+
+	return ret;
+}
+
+static void max77686_rtc_remove(struct platform_device *pdev)
+{
+	struct max77686_rtc_info *info = platform_get_drvdata(pdev);
+
+	free_irq(info->virq, info);
+	regmap_del_irq_chip(info->rtc_irq, info->rtc_irq_data);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int max77686_rtc_suspend(struct device *dev)
+{
+	struct max77686_rtc_info *info = dev_get_drvdata(dev);
+	int ret = 0;
+
+	if (device_may_wakeup(dev)) {
+		struct max77686_rtc_info *info = dev_get_drvdata(dev);
+
+		ret = enable_irq_wake(info->virq);
+	}
+
+	/*
+	 * If the main IRQ (not virtual) is the parent IRQ, then it must be
+	 * disabled during suspend because if it happens while suspended it
+	 * will be handled before resuming I2C.
+	 *
+	 * Since Main IRQ is shared, all its users should disable it to be sure
+	 * it won't fire while one of them is still suspended.
+	 */
+	if (!info->drv_data->rtc_irq_from_platform)
+		disable_irq(info->rtc_irq);
+
+	return ret;
+}
+
+static int max77686_rtc_resume(struct device *dev)
+{
+	struct max77686_rtc_info *info = dev_get_drvdata(dev);
+
+	if (!info->drv_data->rtc_irq_from_platform)
+		enable_irq(info->rtc_irq);
+
+	if (device_may_wakeup(dev)) {
+		struct max77686_rtc_info *info = dev_get_drvdata(dev);
+
+		return disable_irq_wake(info->virq);
+	}
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(max77686_rtc_pm_ops,
+			 max77686_rtc_suspend, max77686_rtc_resume);
+
+static const struct platform_device_id rtc_id[] = {
+	{ .name = "max77686-rtc", .driver_data = (kernel_ulong_t)&max77686_drv_data },
+	{ .name = "max77802-rtc", .driver_data = (kernel_ulong_t)&max77802_drv_data },
+	{ .name = "max77620-rtc", .driver_data = (kernel_ulong_t)&max77620_drv_data },
+	{ .name = "max77714-rtc", .driver_data = (kernel_ulong_t)&max77714_drv_data },
+	{ }
+};
+MODULE_DEVICE_TABLE(platform, rtc_id);
+
+static struct platform_driver max77686_rtc_driver = {
+	.driver		= {
+		.name	= "max77686-rtc",
+		.pm	= &max77686_rtc_pm_ops,
+	},
+	.probe		= max77686_rtc_probe,
+	.remove		= max77686_rtc_remove,
+	.id_table	= rtc_id,
+};
+
+module_platform_driver(max77686_rtc_driver);
+
+MODULE_DESCRIPTION("Maxim MAX77686 RTC driver");
+MODULE_AUTHOR("Chiwoong Byun <woong.byun@samsung.com>");
+MODULE_LICENSE("GPL");