Message-Id: <20250923113441.555284-2-lakshay.piplani@nxp.com>
Date: Tue, 23 Sep 2025 17:04:41 +0530
From: Lakshay Piplani <lakshay.piplani@....com>
To: alexandre.belloni@...tlin.com,
	linux-rtc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	robh@...nel.org,
	krzk+dt@...nel.org,
	conor+dt@...nel.org,
	devicetree@...r.kernel.org
Cc: pankit.garg@....com,
	vikash.bansal@....com,
	priyanka.jain@....com,
	shashank.rebbapragada@....com,
	Lakshay Piplani <lakshay.piplani@....com>,
	Daniel Aguirre <daniel.aguirre@....com>
Subject: [PATCH v4 2/2] rtc: Add NXP PCF85053 driver support

PCF85053 is i2c based RTC which supports timer and calendar
functionality.

Features supported:
1. Read/Write time
2. Get/Set Alarm
3. Wakeup Source
4. Generate up to 32768Hz clock output
5. Primary/Secondary i2c bus

Signed-off-by: Daniel Aguirre <daniel.aguirre@....com>
Signed-off-by: Pankit Garg <pankit.garg@....com>
Signed-off-by: Lakshay Piplani <lakshay.piplani@....com>
---
V3 -> V4: - Handle multi-host ownership explicitly using primary/secondary bus hadling.
          - Probe no longer changes any CTRL bits unconditionally and do not clear ST/AF/OF
            avoiding lost interrupts or silent mode changes.
          - Read/Set time & alarm now respect HF(12/24h) and DM(BCD/BIN) converting
            hour fields correctly for all combinations.
          - Minor changes: drop noisy warnings, tidy error paths/comments.
V2 -> V3: Add MAINTAINERS file changes to this patch
V1 -> V2: no changes

 MAINTAINERS                |   7 +
 drivers/rtc/Kconfig        |  10 +
 drivers/rtc/Makefile       |   1 +
 drivers/rtc/rtc-pcf85053.c | 734 +++++++++++++++++++++++++++++++++++++
 4 files changed, 752 insertions(+)
 create mode 100644 drivers/rtc/rtc-pcf85053.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 6bbe4b4f8ec0..b835c2787e63 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18352,6 +18352,13 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/sound/nxp,tfa989x.yaml
 F:	sound/soc/codecs/tfa989x.c
 
+NXP RTC PCF85053 DRIVER
+M:	Pankit Gargi <pankit.garg@....com>
+M:	Lakshay Piplani <lakshay.piplani@....com>
+L:	linux-kernel@...r.kernel.org
+S:	Maintained
+F:	drivers/rtc/rtc-pcf85053.c
+
 NZXT-KRAKEN2 HARDWARE MONITORING DRIVER
 M:	Jonas Malaco <jonas@...tocubo.io>
 L:	linux-hwmon@...r.kernel.org
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 64f6e9756aff..59ef0b6a53a7 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -974,6 +974,16 @@ config RTC_DRV_PCF85063
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-pcf85063.
 
+config RTC_DRV_PCF85053
+        tristate "NXP PCF85053"
+        depends on OF
+        help
+          If you say yes here you get support for the NXP PCF85053 I2C Bootable CPU RTC
+          chip.
+
+          This driver can also be built as a module. If so, the module
+          will be called rtc-pcf85053.
+
 config RTC_DRV_RV3029C2
 	tristate "Micro Crystal RV3029/3049"
 	depends on RTC_I2C_AND_SPI
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 789bddfea99d..7b2f379d10a9 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -128,6 +128,7 @@ obj-$(CONFIG_RTC_DRV_PCAP)	+= rtc-pcap.o
 obj-$(CONFIG_RTC_DRV_PCF2123)	+= rtc-pcf2123.o
 obj-$(CONFIG_RTC_DRV_PCF2127)	+= rtc-pcf2127.o
 obj-$(CONFIG_RTC_DRV_PCF85063)	+= rtc-pcf85063.o
+obj-$(CONFIG_RTC_DRV_PCF85053)  += rtc-pcf85053.o
 obj-$(CONFIG_RTC_DRV_PCF8523)	+= rtc-pcf8523.o
 obj-$(CONFIG_RTC_DRV_PCF85363)	+= rtc-pcf85363.o
 obj-$(CONFIG_RTC_DRV_PCF8563)	+= rtc-pcf8563.o
diff --git a/drivers/rtc/rtc-pcf85053.c b/drivers/rtc/rtc-pcf85053.c
new file mode 100644
index 000000000000..4eec1a661b6b
--- /dev/null
+++ b/drivers/rtc/rtc-pcf85053.c
@@ -0,0 +1,734 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright 2025 NXP
+
+#include <linux/bcd.h>
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+#include <linux/pm_wakeirq.h>
+#include <linux/regmap.h>
+
+#define PCF85053_REG_SC		0x00 /* seconds */
+#define PCF85053_REG_SCA	0x01 /* alarm */
+#define PCF85053_REG_MN		0x02 /* minutes */
+#define PCF85053_REG_MNA	0x03 /* alarm */
+#define PCF85053_REG_HR		0x04 /* hour */
+#define PCF85053_REG_HRA	0x05 /* alarm */
+#define PCF85053_REG_DW		0x06 /* day of week */
+#define PCF85053_REG_DM		0x07 /* day of month */
+#define PCF85053_REG_MO		0x08 /* month */
+#define PCF85053_REG_YR		0x09 /* year */
+#define PCF85053_REG_CTRL	0x0A /* timer control */
+#define PCF85053_REG_ST		0x0B /* status */
+#define PCF85053_REG_CLKO	0x0C /* clock out */
+#define PCF85053_REG_ACC	0x14 /* xclk access */
+
+#define PCF85053_BIT_AF		BIT(7)
+#define PCF85053_BIT_ST		BIT(7)
+#define PCF85053_BIT_DM		BIT(6)
+#define PCF85053_BIT_HF		BIT(5)
+#define PCF85053_BIT_DSM	BIT(4)
+#define PCF85053_BIT_AIE	BIT(3)
+#define PCF85053_BIT_OFIE	BIT(2)
+#define PCF85053_BIT_CIE	BIT(1)
+#define PCF85053_BIT_TWO	BIT(0)
+#define PCF85053_BIT_XCLK	BIT(7)
+
+#define PCF85053_REG_BAT_MASK	0x07 /* Battery mask */
+#define PCF85053A_BVL_MASK 0x07
+#define PCF85053A_BVL_LOW_THRESHOLD 0x02
+#define PCF85053_REG_CLKO_F_MASK	0x03 /* Frequenc mask */
+#define PCF85053_REG_CLKO_CKE	0x80 /* clock out enabled */
+#define PCF85053_BIT_OF	BIT(6)
+
+#define PCF85053_HR_PM	BIT(7)
+#define PCF85053_HR_24H_MASK	GENMASK(5, 0)
+
+struct pcf85053_config {
+	const struct regmap_config regmap;
+	unsigned has_alarms:1;
+};
+
+struct pcf85053 {
+	struct rtc_device *rtc;
+	struct i2c_client *client;
+	struct regmap	*regmap;
+#ifdef CONFIG_COMMON_CLK
+	struct clk_hw clkout_hw;
+#endif
+	bool is_primary;
+};
+
+static inline int pcf85053_read_two_bit(struct pcf85053 *pcf85053, bool *two)
+{
+	unsigned int ctrl;
+	int err;
+
+	err = regmap_read(pcf85053->regmap, PCF85053_REG_CTRL, &ctrl);
+	if (err)
+		return err;
+
+	*two = !!(ctrl & PCF85053_BIT_TWO);
+
+	return 0;
+}
+
+static inline bool pcf85053_time_write_access(struct pcf85053 *pcf85053)
+{
+	bool two;
+
+	if (pcf85053_read_two_bit(pcf85053, &two))
+		return false;
+
+	/* Primary writes iff TWO=1; secondary writes iff TWO=0 */
+	return pcf85053->is_primary ? two : !two;
+}
+
+static int pcf85053_set_alarm_mode(struct device *dev, bool on)
+{
+	struct pcf85053 *pcf85053 = dev_get_drvdata(dev);
+	unsigned int val;
+	int err;
+
+	val = on ? PCF85053_BIT_AIE : 0;
+	val &= ~(PCF85053_BIT_CIE | PCF85053_BIT_OFIE);
+
+	err = regmap_update_bits(pcf85053->regmap, PCF85053_REG_CTRL,
+				 PCF85053_BIT_AIE | PCF85053_BIT_CIE | PCF85053_BIT_OFIE,
+				 val);
+	if (err)
+		return err;
+
+	return regmap_update_bits(pcf85053->regmap, PCF85053_REG_ST,
+				  PCF85053_BIT_AF, 0);
+}
+
+static int pcf85053_get_alarm_mode(struct device *dev,
+				   unsigned char *alarm_enable, unsigned char *alarm_flag)
+{
+	struct pcf85053 *pcf85053 = dev_get_drvdata(dev);
+	unsigned int val;
+	int err;
+
+	if (alarm_enable) {
+		err = regmap_read(pcf85053->regmap, PCF85053_REG_CTRL, &val);
+		if (err)
+			return err;
+
+		*alarm_enable = val & PCF85053_BIT_AIE;
+	}
+
+	if (alarm_flag) {
+		err = regmap_read(pcf85053->regmap, PCF85053_REG_ST, &val);
+		if (err)
+			return err;
+
+		*alarm_flag = val & PCF85053_BIT_AF;
+	}
+
+	return 0;
+}
+
+static irqreturn_t pcf85053_irq(int irq, void *dev_id)
+{
+	struct pcf85053 *pcf85053 = i2c_get_clientdata(dev_id);
+	unsigned char alarm_flag;
+	unsigned char alarm_enable;
+	int err;
+
+	err = pcf85053_get_alarm_mode(&pcf85053->client->dev, &alarm_enable, &alarm_flag);
+	if (err)
+		return IRQ_NONE;
+
+	if (!alarm_flag)
+		return IRQ_NONE;
+
+	rtc_update_irq(pcf85053->rtc, 1, RTC_IRQF | RTC_AF);
+	pcf85053_set_alarm_mode(&pcf85053->client->dev, false);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * In the routines that deal directly with the PCF85053 hardware, we use
+ * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
+ */
+static int pcf85053_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct pcf85053 *pcf85053 = dev_get_drvdata(dev);
+	unsigned int ctrl, st, h12;
+	bool is_24h, is_bin;
+	u8 regs[10], hr;
+	int err;
+
+	err = regmap_read(pcf85053->regmap, PCF85053_REG_CTRL, &ctrl);
+	if (err)
+		return err;
+
+	err = regmap_read(pcf85053->regmap, PCF85053_REG_ST, &st);
+	if (err)
+		return err;
+
+	if (ctrl & PCF85053_BIT_ST)
+		dev_warn(dev, "RTC is stopped; time may be invalid\n");
+
+	err = regmap_bulk_read(pcf85053->regmap, PCF85053_REG_SC, regs, sizeof(regs));
+	if (err)
+		return err;
+
+	if (ctrl & PCF85053_BIT_DM) {
+		tm->tm_sec = regs[PCF85053_REG_SC] & 0x7F;
+		tm->tm_min = regs[PCF85053_REG_MN] & 0x7F;
+		tm->tm_mday = regs[PCF85053_REG_DM] & 0x3F;
+		tm->tm_mon = (regs[PCF85053_REG_MO] & 0x1F) - 1;
+		tm->tm_year = regs[PCF85053_REG_YR] + 100;
+	} else {
+		tm->tm_sec = bcd2bin(regs[PCF85053_REG_SC] & 0x7F);
+		tm->tm_min = bcd2bin(regs[PCF85053_REG_MN] & 0x7F);
+		tm->tm_mday = bcd2bin(regs[PCF85053_REG_DM] & 0x3F);
+		tm->tm_mon = bcd2bin(regs[PCF85053_REG_MO] & 0x1F) - 1;
+		tm->tm_year = bcd2bin(regs[PCF85053_REG_YR]) + 100;
+	}
+	tm->tm_wday = regs[PCF85053_REG_DW] & 0x07;
+
+	hr = regs[PCF85053_REG_HR];
+	is_24h = ctrl & PCF85053_BIT_HF;
+	is_bin = ctrl & PCF85053_BIT_DM;
+
+	if (is_24h) {
+		tm->tm_hour = is_bin
+		? (hr & PCF85053_HR_24H_MASK)
+		: bcd2bin(hr & PCF85053_HR_24H_MASK);
+	} else {
+		if (is_bin) {
+			h12 = hr & PCF85053_HR_24H_MASK;
+		} else {
+			h12 = is_bin ? (hr & PCF85053_HR_24H_MASK) :
+					   bcd2bin(hr & PCF85053_HR_24H_MASK);
+
+			tm->tm_hour = (h12 == 12) ? ((hr & PCF85053_HR_PM) ? 12 : 0) :
+				       ((hr & PCF85053_HR_PM) ? h12 + 12 : h12);
+			}
+		}
+
+	return 0;
+}
+
+static int pcf85053_rtc_set_time(struct device *dev, struct rtc_time *tm)
+
+{
+	struct pcf85053 *pcf85053 = dev_get_drvdata(dev);
+	unsigned int ctrl, h12;
+	int err, ret;
+	u8 buf[10];
+	bool pm;
+
+	/*
+	 * By default, secondary have write access to time registers as TWO
+	 * bit is 0 by default, if we set nxp,interface = "primary" and the
+	 * nxp,write-access in device tree, then TWO bits gets set and primary
+	 * gets write access to time registers.
+	 */
+	if (!pcf85053_time_write_access(pcf85053))
+		return -EACCES;
+
+	err = regmap_read(pcf85053->regmap, PCF85053_REG_CTRL, &ctrl);
+	if (err)
+		return err;
+
+	buf[0] = tm->tm_sec & 0x7F;
+	buf[1] = 0;
+	buf[2] = tm->tm_min & 0x7F;
+	buf[3] = 0;
+	buf[5] = 0;
+	buf[6] = tm->tm_wday & 0x07;
+	buf[7] = tm->tm_mday & 0x3F;
+	buf[8] = (tm->tm_mon + 1) & 0x1F;
+	buf[9] = (tm->tm_year - 100) & 0xFF;
+
+	if (ctrl & PCF85053_BIT_HF) {
+		buf[4] = tm->tm_hour & PCF85053_HR_24H_MASK;
+	} else {
+		pm = tm->tm_hour >= 12;
+		h12 = (tm->tm_hour % 12) ? (tm->tm_hour % 12) : 12;
+		buf[4] = (h12 & PCF85053_HR_24H_MASK) | (pm << 7);
+	}
+
+	if (!(ctrl & PCF85053_BIT_DM)) {
+		buf[0] = bin2bcd(buf[0]);
+		buf[2] = bin2bcd(buf[2]);
+		buf[4] = bin2bcd(buf[4] & PCF85053_HR_24H_MASK) | (buf[4] & PCF85053_HR_PM);
+		buf[7] = bin2bcd(buf[7]);
+		buf[8] = bin2bcd(buf[8]);
+		buf[9] = bin2bcd(buf[9]);
+	}
+
+	if (pcf85053->is_primary) {
+		err = regmap_update_bits(pcf85053->regmap, PCF85053_REG_CTRL,
+					 PCF85053_BIT_ST, PCF85053_BIT_ST);
+		if (err)
+			return err;
+
+		ret = regmap_bulk_write(pcf85053->regmap, PCF85053_REG_SC, buf, sizeof(buf));
+		err = regmap_update_bits(pcf85053->regmap, PCF85053_REG_CTRL,
+					 PCF85053_BIT_ST, 0);
+		return ret ? ret : err;
+	}
+
+	return regmap_bulk_write(pcf85053->regmap, PCF85053_REG_SC, buf, sizeof(buf));
+}
+
+static int pcf85053_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *tm)
+{
+	struct pcf85053 *pcf85053 = dev_get_drvdata(dev);
+	unsigned int ctrl, h12;
+	bool is_24h, is_bin, pm;
+	u8 buf[5];
+	u8 hr;
+	int err;
+
+	err = regmap_read(pcf85053->regmap, PCF85053_REG_CTRL, &ctrl);
+	if (err)
+		return err;
+
+	err = regmap_bulk_read(pcf85053->regmap, PCF85053_REG_SCA, buf, sizeof(buf));
+	if (err)
+		return err;
+
+	if (ctrl & PCF85053_BIT_DM) {
+		tm->time.tm_sec = buf[0] & 0x7F; /* SCA */
+		tm->time.tm_min = buf[2] & 0x7F; /* MNA */
+	} else {
+		tm->time.tm_sec = bcd2bin(buf[0] & 0x7F);
+		tm->time.tm_min = bcd2bin(buf[2] & 0x7F);
+	}
+
+	hr = buf[4];
+	is_24h = !!(ctrl & PCF85053_BIT_HF);
+	is_bin = !!(ctrl & PCF85053_BIT_DM);
+
+	if (is_24h) {
+		tm->time.tm_hour = is_bin
+		? (hr & PCF85053_HR_24H_MASK)
+		: bcd2bin(hr & PCF85053_HR_24H_MASK);
+	} else {
+		pm = !!(hr & PCF85053_HR_PM);
+
+		if (is_bin)
+			h12 = (hr & PCF85053_HR_24H_MASK);
+		else
+			h12 = (bcd2bin(hr & PCF85053_HR_24H_MASK));
+
+		if (h12 == 12)
+			h12 = 0;
+		tm->time.tm_hour = pm ? (h12 + 12) : h12;
+	}
+
+	return pcf85053_get_alarm_mode(dev, &tm->enabled, &tm->pending);
+}
+
+static int pcf85053_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *tm)
+{
+	struct pcf85053 *pcf85053 = dev_get_drvdata(dev);
+	bool is_24h, is_bin, pm;
+	unsigned int ctrl, h12;
+	u8 sec, min, hra;
+	int err;
+
+	/*
+	 * Only primary can set alarm, as secondary have read only access
+	 * to alarm, control and status registers
+	 */
+	if (!pcf85053->is_primary)
+		return -EACCES;
+
+	err = regmap_read(pcf85053->regmap, PCF85053_REG_CTRL, &ctrl);
+	if (err)
+		return err;
+
+	err = regmap_update_bits(pcf85053->regmap, PCF85053_REG_ST,
+				 PCF85053_BIT_AF, 0);
+	if (err)
+		return err;
+
+	is_24h = !!(ctrl & PCF85053_BIT_HF);
+	is_bin = !!(ctrl & PCF85053_BIT_DM);
+
+	sec = tm->time.tm_sec & 0x7F;
+	min = tm->time.tm_min & 0x7F;
+
+	if (is_24h) {
+		hra = tm->time.tm_hour & PCF85053_HR_24H_MASK;
+		if (!is_bin)
+			hra = bin2bcd(hra) & PCF85053_HR_24H_MASK;
+	} else {
+		h12 = tm->time.tm_hour % 12;
+		pm = tm->time.tm_hour >= 12;
+		if (h12 == 0)
+			h12 = 12;
+
+		if (is_bin)
+			hra = (h12 & PCF85053_HR_24H_MASK) | (pm << 7);
+		else
+			hra = (bin2bcd(h12) & PCF85053_HR_24H_MASK) | (pm << 7);
+	}
+
+	if (!is_bin) {
+		sec = bin2bcd(sec);
+		min = bin2bcd(min);
+	}
+
+	err = regmap_write(pcf85053->regmap, PCF85053_REG_SCA, sec);
+	if (err)
+		return err;
+
+	err = regmap_write(pcf85053->regmap, PCF85053_REG_MNA, min);
+	if (err)
+		return err;
+
+	err = regmap_write(pcf85053->regmap, PCF85053_REG_HRA, hra);
+	if (err)
+		return err;
+
+	return pcf85053_set_alarm_mode(dev, tm->enabled);
+}
+
+static int pcf85053_irq_enable(struct device *dev, unsigned int enabled)
+{
+	dev_dbg(dev, "%s: alarm enable=%d\n", __func__, enabled);
+
+	return pcf85053_set_alarm_mode(dev, enabled);
+}
+
+static int pcf85053_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
+{
+	struct pcf85053 *pcf85053 = dev_get_drvdata(dev);
+	unsigned int val = 0, vl_status = 0;
+	unsigned int bvl;
+	int status;
+
+	switch (cmd) {
+	case RTC_VL_READ:
+		status = regmap_read(pcf85053->regmap, PCF85053_REG_ST, &val);
+		if (status)
+			return status;
+
+		if (val & PCF85053_BIT_OF)
+			vl_status |= RTC_VL_DATA_INVALID;
+
+		bvl = val & PCF85053A_BVL_MASK;
+
+		if (bvl == 0x00)
+			vl_status |= RTC_VL_BACKUP_EMPTY;
+		else if (bvl <= PCF85053A_BVL_LOW_THRESHOLD)
+			vl_status |= RTC_VL_BACKUP_LOW;
+
+		return put_user(vl_status, (unsigned int __user *)arg);
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+}
+
+#ifdef CONFIG_COMMON_CLK
+/*
+ * Handling of the clkout
+ */
+
+#define clkout_hw_to_pcf85053(_hw) container_of(_hw, struct pcf85053, clkout_hw)
+
+static const int clkout_rates[] = {
+	32768,
+	1024,
+	32,
+	1,
+};
+
+static unsigned long pcf85053_clkout_recalc_rate(struct clk_hw *hw,
+						 unsigned long parent_rate)
+{
+	struct pcf85053 *pcf85053 = clkout_hw_to_pcf85053(hw);
+	unsigned int val = 0;
+	int err;
+
+	err = regmap_read(pcf85053->regmap, PCF85053_REG_CLKO, &val);
+	if (err)
+		return 0;
+
+	val &= PCF85053_REG_CLKO_F_MASK;
+	return clkout_rates[val];
+}
+
+static int pcf85053_clkout_determine_rate(struct clk_hw *hw,
+					  struct clk_rate_request *req)
+{
+	int i;
+	unsigned long best = 0;
+
+	for (i = 0; i < ARRAY_SIZE(clkout_rates); i++) {
+		if (clkout_rates[i] <= req->rate) {
+			best = clkout_rates[i];
+			break;
+		}
+	}
+	if (!best)
+		best = clkout_rates[ARRAY_SIZE(clkout_rates) - 1];
+
+	req->rate = best;
+	return 0;
+}
+
+static int pcf85053_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
+				    unsigned long parent_rate)
+{
+	struct pcf85053 *pcf85053 = clkout_hw_to_pcf85053(hw);
+	unsigned int val = 0;
+	int err, i;
+
+	err = regmap_read(pcf85053->regmap, PCF85053_REG_CLKO, &val);
+	if (err)
+		return err;
+
+	for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
+		if (clkout_rates[i] == rate) {
+			val &= ~PCF85053_REG_CLKO_F_MASK;
+			val |= i;
+			return regmap_write(pcf85053->regmap, PCF85053_REG_CLKO, val);
+		}
+
+	return -EINVAL;
+}
+
+static int pcf85053_clkout_control(struct clk_hw *hw, bool enable)
+{
+	struct pcf85053 *pcf85053 = clkout_hw_to_pcf85053(hw);
+	unsigned int val = 0;
+	int err;
+
+	if (!pcf85053->is_primary)
+		return -EACCES;
+
+	val = PCF85053_BIT_XCLK;
+	err = regmap_write(pcf85053->regmap, PCF85053_REG_ACC, val);
+	if (err)
+		return err;
+
+	err = regmap_read(pcf85053->regmap, PCF85053_REG_CLKO, &val);
+	if (err)
+		return err;
+
+	if (enable)
+		val |= PCF85053_REG_CLKO_CKE;
+	else
+		val &= ~PCF85053_REG_CLKO_CKE;
+
+	return regmap_write(pcf85053->regmap, PCF85053_REG_CLKO, val);
+}
+
+static int pcf85053_clkout_prepare(struct clk_hw *hw)
+{
+	return pcf85053_clkout_control(hw, 1);
+}
+
+static void pcf85053_clkout_unprepare(struct clk_hw *hw)
+{
+	pcf85053_clkout_control(hw, 0);
+}
+
+static int pcf85053_clkout_is_prepared(struct clk_hw *hw)
+{
+	struct pcf85053 *pcf85053 = clkout_hw_to_pcf85053(hw);
+	unsigned int val = 0;
+	int err;
+
+	err = regmap_read(pcf85053->regmap, PCF85053_REG_CLKO, &val);
+	if (err)
+		return err;
+
+	return val & PCF85053_REG_CLKO_CKE;
+}
+
+static const struct clk_ops pcf85053_clkout_ops = {
+	.prepare = pcf85053_clkout_prepare,
+	.unprepare = pcf85053_clkout_unprepare,
+	.is_prepared = pcf85053_clkout_is_prepared,
+	.recalc_rate = pcf85053_clkout_recalc_rate,
+	.determine_rate = pcf85053_clkout_determine_rate,
+	.set_rate = pcf85053_clkout_set_rate,
+};
+
+static struct clk *pcf85053_clkout_register_clk(struct pcf85053 *pcf85053)
+{
+	struct i2c_client *client = pcf85053->client;
+	struct device_node *node = client->dev.of_node;
+	struct clk *clk;
+	struct clk_init_data init;
+
+	init.name = "pcf85053-clkout";
+	init.ops = &pcf85053_clkout_ops;
+	init.flags = 0;
+	init.parent_names = NULL;
+	init.num_parents = 0;
+	pcf85053->clkout_hw.init = &init;
+
+	/* optional override of the clockname */
+	of_property_read_string(node, "clock-output-names", &init.name);
+
+	/* register the clock */
+	clk = devm_clk_register(&client->dev, &pcf85053->clkout_hw);
+
+	if (!IS_ERR(clk))
+		of_clk_add_provider(node, of_clk_src_simple_get, clk);
+
+	return clk;
+}
+#endif
+
+static const struct rtc_class_ops pcf85053_rtc_ops = {
+	.read_time	= pcf85053_rtc_read_time,
+	.set_time	= pcf85053_rtc_set_time,
+	.read_alarm	= pcf85053_rtc_read_alarm,
+	.set_alarm	= pcf85053_rtc_set_alarm,
+	.alarm_irq_enable = pcf85053_irq_enable,
+	.ioctl		= pcf85053_ioctl,
+};
+
+static const struct pcf85053_config config_pcf85053 = {
+	.regmap = {
+		.reg_bits = 8,
+		.val_bits = 8,
+		.max_register = 0x1D,
+	},
+	.has_alarms = 1,
+};
+
+static int pcf85053_probe(struct i2c_client *client)
+{
+	struct pcf85053 *pcf85053;
+	const struct pcf85053_config *config;
+	const char *iface = NULL;
+	int err;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
+				     I2C_FUNC_SMBUS_BYTE |
+				     I2C_FUNC_SMBUS_BLOCK_DATA))
+		return -ENODEV;
+
+	pcf85053 = devm_kzalloc(&client->dev, sizeof(struct pcf85053),
+				GFP_KERNEL);
+	if (!pcf85053)
+		return -ENOMEM;
+
+	config = i2c_get_match_data(client);
+	if (!config)
+		return -ENODEV;
+
+	pcf85053->regmap = devm_regmap_init_i2c(client, &config->regmap);
+	if (IS_ERR(pcf85053->regmap))
+		return PTR_ERR(pcf85053->regmap);
+
+	i2c_set_clientdata(client, pcf85053);
+
+	pcf85053->client = client;
+	device_set_wakeup_capable(&client->dev, 1);
+
+	pcf85053->is_primary = true;
+
+	if (of_property_read_string(client->dev.of_node, "nxp,interface", &iface))
+		return dev_err_probe(&client->dev, -EINVAL,
+				     "Missing mandatory property: nxp,interface\n");
+	if (!strcmp(iface, "primary"))
+		pcf85053->is_primary = true;
+	else if (!strcmp(iface, "secondary"))
+		pcf85053->is_primary = false;
+	else
+		return dev_err_probe(&client->dev, -EINVAL,
+				     "Invalid value for nxp,interface: %s\n", iface);
+
+	if (pcf85053->is_primary) {
+		unsigned int ctrl;
+		int err;
+
+		err = regmap_read(pcf85053->regmap, PCF85053_REG_CTRL, &ctrl);
+		if (err)
+			return err;
+
+		if (of_property_read_bool(client->dev.of_node, "nxp,write-access")) {
+			if (!(ctrl & PCF85053_BIT_TWO)) {
+				err = regmap_update_bits(pcf85053->regmap, PCF85053_REG_CTRL,
+							 PCF85053_BIT_TWO, PCF85053_BIT_TWO);
+				if (err)
+					return err;
+			}
+			dev_dbg(&client->dev, "Ownership set: TWO=1 (primary writes)\n");
+		} else {
+			/* TWO (Time Write Ownership) bit defaults to 0 (Secondary) */
+			dev_dbg(&client->dev, "Default ownership set: TWO=0 (secondary writes)\n");
+		}
+	}
+
+	pcf85053->rtc = devm_rtc_allocate_device(&client->dev);
+	if (IS_ERR(pcf85053->rtc))
+		return PTR_ERR(pcf85053->rtc);
+
+	pcf85053->rtc->ops = &pcf85053_rtc_ops;
+	pcf85053->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
+	pcf85053->rtc->range_max = RTC_TIMESTAMP_END_2099;
+	clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, pcf85053->rtc->features);
+	clear_bit(RTC_FEATURE_ALARM, pcf85053->rtc->features);
+
+	if (config->has_alarms && client->irq > 0) {
+		err = devm_request_threaded_irq(&client->dev, client->irq,
+						NULL, pcf85053_irq,
+						IRQF_ONESHOT | IRQF_TRIGGER_FALLING,
+						"pcf85053", client);
+		if (err) {
+			dev_err(&client->dev, "unable to request IRQ %d\n", client->irq);
+		} else {
+			set_bit(RTC_FEATURE_ALARM, pcf85053->rtc->features);
+			device_init_wakeup(&client->dev, true);
+			err = dev_pm_set_wake_irq(&client->dev, client->irq);
+			if (err)
+				dev_err(&client->dev, "failed to enable irq wake\n");
+		}
+	}
+
+#ifdef CONFIG_COMMON_CLK
+	/* register clk in common clk framework */
+	pcf85053_clkout_register_clk(pcf85053);
+#endif
+
+	return devm_rtc_register_device(pcf85053->rtc);
+}
+
+static const struct i2c_device_id pcf85053_id[] = {
+	{ "pcf85053", .driver_data = (kernel_ulong_t)&config_pcf85053 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, pcf85053_id);
+
+static const struct of_device_id pcf85053_of_match[] = {
+	{ .compatible = "nxp,pcf85053", .data = &config_pcf85053 },
+	{}
+};
+MODULE_DEVICE_TABLE(of, pcf85053_of_match);
+
+static struct i2c_driver pcf85053_driver = {
+	.driver		= {
+		.name	= "rtc-pcf85053",
+		.of_match_table = of_match_ptr(pcf85053_of_match),
+	},
+	.probe		= pcf85053_probe,
+	.id_table	= pcf85053_id,
+};
+
+module_i2c_driver(pcf85053_driver);
+
+MODULE_AUTHOR("Pankit Garg <pankit.garg@....com>");
+MODULE_AUTHOR("Lakshay Piplani <lakshay.piplani@....com>");
+MODULE_DESCRIPTION("NXP pcf85053 RTC driver");
+MODULE_LICENSE("GPL");
-- 
2.25.1

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