drivers: rtc: add PCF85063 support

Add support for the Microcrystal RV8263 and compatible RTCs. The
driver's name was taken from linux. It should work with any NXP PCF85063
compatible RTCs. It was tested with a RV8263.

Signed-off-by: Michael Walle <mwalle@kernel.org>

drivers/rtc/Kconfig

@@ -161,6 +161,14 @@ config RTC_MAX313XX
 	  - Temperature sensor
 	  - CLKOUT generation
 
+config RTC_PCF85063
+	bool "Enable PCF85063 driver"
+	depends on DM_I2C
+	depends on DM_RTC
+	help
+	  If you say yes here you get support for the NXP PCF85063 RTC
+	  and compatible chips.
+
 config RTC_PCF8563
 	bool "Philips PCF8563"
 	help

drivers/rtc/Makefile

@@ -27,6 +27,7 @@ obj-$(CONFIG_RTC_MC146818) += mc146818.o
 obj-$(CONFIG_MCFRTC) += mcfrtc.o
 obj-$(CONFIG_RTC_MV) += mvrtc.o
 obj-$(CONFIG_RTC_MXS) += mxsrtc.o
+obj-$(CONFIG_RTC_PCF85063) += pcf85063.o
 obj-$(CONFIG_RTC_PCF8563) += pcf8563.o
 obj-$(CONFIG_RTC_PCF2127) += pcf2127.o
 obj-$(CONFIG_RTC_PL031) += pl031.o

drivers/rtc/pcf85063.c

@@ -0,0 +1,107 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * PCF85063 and compatible I2C RTC driver
+ *
+ * Copyright (c) 2025 Kontron Europe GmbH.
+ */
+
+#include <dm.h>
+#include <i2c.h>
+#include <rtc.h>
+#include <dm/device_compat.h>
+
+#define PCF85063_REG_CTRL1		0x00 /* status */
+#define PCF85063_REG_CTRL1_SR		0x58
+
+#define PCF85063_REG_SC			0x04 /* datetime */
+#define PCF85063_REG_SC_OS		0x80
+
+static int pcf85063_get_time(struct udevice *dev, struct rtc_time *tm)
+{
+	u8 regs[7];
+	int ret;
+
+	ret = dm_i2c_read(dev, PCF85063_REG_SC, regs, sizeof(regs));
+	if (ret)
+		return ret;
+
+	if (regs[0] & PCF85063_REG_SC_OS) {
+		dev_err(dev, "Power loss detected, Invalid time\n");
+		return -EINVAL;
+	}
+
+	tm->tm_sec = bcd2bin(regs[0] & 0x7f);
+	tm->tm_min = bcd2bin(regs[1] & 0x7f);
+	tm->tm_hour = bcd2bin(regs[2] & 0x3f);
+	tm->tm_mday = bcd2bin(regs[3] & 0x3f);
+	tm->tm_wday = regs[4] & 0x07;
+	tm->tm_mon = bcd2bin(regs[5] & 0x1f) - 1;
+	tm->tm_year = bcd2bin(regs[6]) + 2000;
+
+	return 0;
+}
+
+static int pcf85063_set_time(struct udevice *dev, const struct rtc_time *tm)
+{
+	u8 regs[7];
+
+	if (tm->tm_year < 2000 || tm->tm_year > 2099) {
+		dev_err(dev, "Year must be between 2000 and 2099.\n");
+		return -EINVAL;
+	}
+
+	regs[0] = bin2bcd(tm->tm_sec);
+	regs[1] = bin2bcd(tm->tm_min);
+	regs[2] = bin2bcd(tm->tm_hour);
+	regs[3] = bin2bcd(tm->tm_mday);
+	regs[4] = tm->tm_wday;
+	regs[5] = bin2bcd(tm->tm_mon + 1);
+	regs[6] = bin2bcd(tm->tm_year % 100);
+
+	return dm_i2c_write(dev, PCF85063_REG_SC, regs, sizeof(regs));
+}
+
+static int pcf85063_reset(struct udevice *dev)
+{
+	return dm_i2c_reg_write(dev, PCF85063_REG_CTRL1, PCF85063_REG_CTRL1_SR);
+}
+
+static int pcf85063_read(struct udevice *dev, unsigned int offset, u8 *buf,
+			 unsigned int len)
+{
+	return dm_i2c_read(dev, offset, buf, len);
+}
+
+static int pcf85063_write(struct udevice *dev, unsigned int offset,
+			  const u8 *buf, unsigned int len)
+{
+	return dm_i2c_write(dev, offset, buf, len);
+}
+
+static const struct rtc_ops pcf85063_rtc_ops = {
+	.get = pcf85063_get_time,
+	.set = pcf85063_set_time,
+	.reset = pcf85063_reset,
+	.read = pcf85063_read,
+	.write = pcf85063_write,
+};
+
+static int pcf85063_probe(struct udevice *dev)
+{
+	i2c_set_chip_flags(dev, DM_I2C_CHIP_RD_ADDRESS | DM_I2C_CHIP_WR_ADDRESS);
+
+	return 0;
+}
+
+static const struct udevice_id pcf85063_of_id[] = {
+	{ .compatible = "microcrystal,rv8263" },
+	{ }
+};
+
+U_BOOT_DRIVER(rtc_pcf85063) = {
+	.name	= "rtc-pcf85063",
+	.id     = UCLASS_RTC,
+	.probe  = pcf85063_probe,
+	.of_match = pcf85063_of_id,
+	.ops    = &pcf85063_rtc_ops,
+};