drivers: rtc: add RV3032 support

Add support for the Microcrystal RV3032 RTC.

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

drivers/rtc/Kconfig

@@ -194,6 +194,13 @@ config RTC_RV3029
 	  This driver supports reading and writing the RTC/calendar and the
 	  battery-baced SRAM section.
 
+config RTC_RV3032
+	bool "Enable RV3032 driver"
+	depends on DM_RTC
+	help
+	  If you say yes here you get support for the Micro Crystal RV3032
+	  RTC.
+
 config RTC_RV8803
 	bool "Enable RV8803 driver"
 	depends on DM_RTC

drivers/rtc/Makefile

@@ -34,6 +34,7 @@ obj-$(CONFIG_RTC_PL031) += pl031.o
 obj-$(CONFIG_RTC_PT7C4338) += pt7c4338.o
 obj-$(CONFIG_RTC_RV3028) += rv3028.o
 obj-$(CONFIG_RTC_RV3029) += rv3029.o
+obj-$(CONFIG_RTC_RV3032) += rv3032.o
 obj-$(CONFIG_RTC_RV8803) += rv8803.o
 obj-$(CONFIG_RTC_RX8025) += rx8025.o
 obj-$(CONFIG_RTC_RX8010SJ) += rx8010sj.o

drivers/rtc/rv3032.c

@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Micro Crystal RV3032 I2C RTC driver
+ *
+ * Copyright (c) 2025 Kontron Europe GmbH.
+ */
+
+#include <dm.h>
+#include <i2c.h>
+#include <rtc.h>
+#include <dm/device_compat.h>
+
+#define RV3032_REG_SEC			0x01
+#define RV3032_REG_STATUS		0x0d
+#define RV3032_REG_STATUS_VLF		BIT(0)
+#define RV3032_REG_STATUS_PORF		BIT(1)
+
+static int rv3032_get_time(struct udevice *dev, struct rtc_time *tm)
+{
+	int ret, status;
+	u8 regs[7];
+
+	status = dm_i2c_reg_read(dev, RV3032_REG_STATUS);
+	if (status < 0)
+		return status;
+
+	if (status & (RV3032_REG_STATUS_PORF | RV3032_REG_STATUS_VLF)) {
+		dev_err(dev, "Power loss detected, Invalid time\n");
+		return -EINVAL;
+	}
+
+	ret = dm_i2c_read(dev, RV3032_REG_SEC, regs, sizeof(regs));
+	if (ret)
+		return ret;
+
+	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 rv3032_set_time(struct udevice *dev, const struct rtc_time *tm)
+{
+	u8 regs[7];
+	int ret;
+
+	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);
+
+	ret = dm_i2c_write(dev, RV3032_REG_SEC, regs, sizeof(regs));
+	if (ret)
+		return ret;
+
+	return dm_i2c_reg_clrset(dev, RV3032_REG_STATUS,
+				 RV3032_REG_STATUS_PORF | RV3032_REG_STATUS_VLF,
+				 0);
+}
+
+static int rv3032_read(struct udevice *dev, unsigned int offset, u8 *buf,
+		       unsigned int len)
+{
+	return dm_i2c_read(dev, offset, buf, len);
+}
+
+static int rv3032_write(struct udevice *dev, unsigned int offset,
+			const u8 *buf, unsigned int len)
+{
+	return dm_i2c_write(dev, offset, buf, len);
+}
+
+static int rv3032_reset(struct udevice *dev)
+{
+	/*
+	 * There is no reset, but the "date reset" command needs this op to
+	 * actually set the default time
+	 */
+	return 0;
+}
+
+static const struct rtc_ops rv3032_rtc_ops = {
+	.get = rv3032_get_time,
+	.set = rv3032_set_time,
+	.read = rv3032_read,
+	.write = rv3032_write,
+	.reset = rv3032_reset,
+};
+
+static int rv3032_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 rv3032_of_id[] = {
+	{ .compatible = "microcrystal,rv3032" },
+	{ }
+};
+
+U_BOOT_DRIVER(rtc_rv3032) = {
+	.name	= "rtc-rv3032",
+	.id     = UCLASS_RTC,
+	.probe  = rv3032_probe,
+	.of_match = rv3032_of_id,
+	.ops    = &rv3032_rtc_ops,
+};