drivers: rtc: add silabs siwx91x rtc driver

Add the support of silabs siwx91x basic rtc driver.

Signed-off-by: Martin Hoff <martin.hoff@silabs.com>

drivers/clock_control/clock_control_silabs_siwx91x.c

@@ -85,6 +85,10 @@ static int siwx91x_clock_on(const struct device *dev, clock_control_subsys_t sys
 	case SIWX91X_CLK_QSPI:
 		RSI_CLK_Qspi2ClkConfig(M4CLK, QSPI_ULPREFCLK, 0, 0, 0);
 		break;
+	case SIWX91X_CLK_RTC:
+		/* Already done in sl_calendar_init()*/
+		RSI_PS_NpssPeriPowerUp(SLPSS_PWRGATE_ULP_MCURTC | SLPSS_PWRGATE_ULP_TIMEPERIOD);
+		break;
 	default:
 		return -EINVAL;
 	}

drivers/rtc/CMakeLists.txt

@@ -35,3 +35,4 @@ zephyr_library_sources_ifdef(CONFIG_RTC_RV8803 rtc_rv8803.c)
 zephyr_library_sources_ifdef(CONFIG_RTC_BQ32002 rtc_bq32002.c)
 zephyr_library_sources_ifdef(CONFIG_RTC_RX8130CE rtc_rx8130ce.c)
 zephyr_library_sources_ifdef(CONFIG_RTC_DS1337 rtc_ds1337.c)
+zephyr_library_sources_ifdef(CONFIG_RTC_SILABS_SIWX91X rtc_silabs_siwx91x.c)

drivers/rtc/Kconfig

@@ -67,5 +67,6 @@ source "drivers/rtc/Kconfig.rv8803"
 source "drivers/rtc/Kconfig.bq32002"
 source "drivers/rtc/Kconfig.rx8130ce"
 source "drivers/rtc/Kconfig.ds1337"
+source "drivers/rtc/Kconfig.siwx91x"
 
 endif # RTC

drivers/rtc/Kconfig.siwx91x

@@ -0,0 +1,10 @@
+# Copyright (c) 2025 Silicon Laboratories Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+config RTC_SILABS_SIWX91X
+	bool "Silabs siwx91x RTC driver"
+	default y
+	depends on DT_HAS_SILABS_SIWX91X_RTC_ENABLED
+	help
+	  Build the RTC driver for the Silabs SIWX91X SoC (Calendar
+	  hardware block as described in the reference manual).

drivers/rtc/rtc_silabs_siwx91x.c

@@ -0,0 +1,153 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Copyright (c) 2025 Silicon Laboratories Inc.
+ */
+
+#include <zephyr/devicetree.h>
+#include <zephyr/drivers/clock_control.h>
+#include <zephyr/drivers/rtc.h>
+#include <zephyr/logging/log.h>
+#include <zephyr/pm/device.h>
+#include <zephyr/sys/util.h>
+#include "rtc_utils.h"
+#include "sl_si91x_calendar.h"
+
+#define DT_DRV_COMPAT silabs_siwx91x_rtc
+
+LOG_MODULE_REGISTER(siwx91x_rtc, CONFIG_RTC_LOG_LEVEL);
+
+#define TM_YEAR_REF          1900
+#define SIWX91X_RTC_YEAR_MAX 2399
+#define SIWX91X_RTC_YEAR_MIN 2000
+
+struct siwx91x_rtc_config {
+	const struct device *clock_dev;
+	clock_control_subsys_t clock_subsys;
+};
+struct siwx91x_rtc_data {
+	struct k_spinlock lock;
+};
+
+static void rtc_time_to_siwx91x_time_set(const struct rtc_time *tm,
+					 sl_calendar_datetime_config_t *cldr)
+{
+	int full_year = tm->tm_year + TM_YEAR_REF;
+
+	cldr->Year = (full_year % 100);
+	cldr->Century = (full_year >= 2000) ? (full_year - 2000) / 100 : 0;
+	cldr->Month = tm->tm_mon + 1;
+	cldr->Day = tm->tm_mday;
+	cldr->DayOfWeek = (RTC_DAY_OF_WEEK_T)tm->tm_wday;
+	cldr->Hour = tm->tm_hour;
+	cldr->Minute = tm->tm_min;
+	cldr->Second = tm->tm_sec;
+	cldr->MilliSeconds = tm->tm_nsec / NSEC_PER_MSEC;
+}
+
+static void siwx91x_time_to_rtc_time_set(const sl_calendar_datetime_config_t *cldr,
+					 struct rtc_time *tm)
+{
+	int full_year = 2000 + (cldr->Century * 100) + cldr->Year;
+
+	tm->tm_year = full_year - TM_YEAR_REF;
+	tm->tm_mon = cldr->Month - 1;
+	tm->tm_mday = cldr->Day;
+	tm->tm_wday = (int)cldr->DayOfWeek;
+	tm->tm_hour = cldr->Hour;
+	tm->tm_min = cldr->Minute;
+	tm->tm_sec = cldr->Second;
+	tm->tm_nsec = cldr->MilliSeconds * NSEC_PER_MSEC;
+}
+
+static int siwx91x_rtc_set_time(const struct device *dev, const struct rtc_time *timeptr)
+{
+	sl_calendar_datetime_config_t siwx91x_time = {};
+	struct siwx91x_rtc_data *data = dev->data;
+	int year;
+	int ret;
+
+	year = timeptr->tm_year + TM_YEAR_REF;
+	if (year < SIWX91X_RTC_YEAR_MIN || year > SIWX91X_RTC_YEAR_MAX) {
+		return -EINVAL;
+	}
+
+	k_spinlock_key_t key = k_spin_lock(&data->lock);
+
+	LOG_DBG("Set RTC time: year = %d, mon = %d, mday = %d, wday = %d, hour = %d, "
+		"min = %d, sec = %d",
+		timeptr->tm_year, timeptr->tm_mon, timeptr->tm_mday, timeptr->tm_wday,
+		timeptr->tm_hour, timeptr->tm_min, timeptr->tm_sec);
+
+	rtc_time_to_siwx91x_time_set(timeptr, &siwx91x_time);
+
+	ret = sl_si91x_calendar_set_date_time(&siwx91x_time);
+	if (ret) {
+		LOG_WRN("Set Timer returned an error - %d!", ret);
+	}
+
+	k_spin_unlock(&data->lock, key);
+
+	return ret;
+}
+
+static int siwx91x_rtc_get_time(const struct device *dev, struct rtc_time *timeptr)
+{
+	sl_calendar_datetime_config_t siwx91x_time = {};
+	struct siwx91x_rtc_data *data = dev->data;
+	int ret;
+
+	k_spinlock_key_t key = k_spin_lock(&data->lock);
+
+	ret = sl_si91x_calendar_get_date_time(&siwx91x_time);
+	if (ret != 0) {
+		LOG_WRN("Get Timer returned an error - %d!", ret);
+		goto unlock;
+	}
+
+	siwx91x_time_to_rtc_time_set(&siwx91x_time, timeptr);
+
+	LOG_DBG("get time: year = %d, mon = %d, mday = %d, wday = %d, hour = %d, "
+		"min = %d, sec = %d",
+		timeptr->tm_year, timeptr->tm_mon, timeptr->tm_mday, timeptr->tm_wday,
+		timeptr->tm_hour, timeptr->tm_min, timeptr->tm_sec);
+
+unlock:
+	k_spin_unlock(&data->lock, key);
+
+	return ret;
+}
+
+static int siwx91x_rtc_init(const struct device *dev)
+{
+	const struct siwx91x_rtc_config *config = dev->config;
+	int ret;
+
+	ret = clock_control_on(config->clock_dev, config->clock_subsys);
+	if (ret) {
+		return ret;
+	}
+
+	sl_si91x_calendar_init();
+
+	return 0;
+}
+
+static DEVICE_API(rtc, siwx91x_rtc_driver_api) = {
+	.set_time = siwx91x_rtc_set_time,
+	.get_time = siwx91x_rtc_get_time,
+};
+
+#define SIWX91X_RTC_INIT(inst)                                                                     \
+	static const struct siwx91x_rtc_config siwx91x_rtc_config_##inst = {                       \
+		.clock_dev = DEVICE_DT_GET(DT_INST_CLOCKS_CTLR(inst)),                             \
+		.clock_subsys = (clock_control_subsys_t)DT_INST_PHA(inst, clocks, clkid),          \
+	};                                                                                         \
+                                                                                                   \
+	static struct siwx91x_rtc_data siwx91x_rtc_data##inst;                                     \
+                                                                                                   \
+	DEVICE_DT_INST_DEFINE(inst, &siwx91x_rtc_init, NULL, &siwx91x_rtc_data##inst,              \
+			      &siwx91x_rtc_config_##inst, POST_KERNEL, CONFIG_RTC_INIT_PRIORITY,   \
+			      &siwx91x_rtc_driver_api);
+
+DT_INST_FOREACH_STATUS_OKAY(SIWX91X_RTC_INIT)

dts/bindings/rtc/silabs,siwx91x-rtc.yaml

@@ -0,0 +1,12 @@
+# Copyright (c) 2025 Silicon Labatoratories Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+description: Silabs Siwx91x RTC (Real-Time Counter)
+
+compatible: "silabs,siwx91x-rtc"
+
+include: rtc.yaml
+
+properties:
+  reg:
+    required: true

include/zephyr/dt-bindings/clock/silabs/siwx91x-clock.h

@@ -16,5 +16,6 @@
 #define SIWX91X_CLK_PWM           9
 #define SIWX91X_CLK_GSPI         10
 #define SIWX91X_CLK_QSPI         11
+#define SIWX91X_CLK_RTC          12
 
 #endif

modules/hal_silabs/wiseconnect/CMakeLists.txt

@@ -49,7 +49,10 @@ zephyr_library_sources(
   ${WISECONNECT_DIR}/components/device/silabs/si91x/mcu/drivers/systemlevel/src/rsi_pll.c
   ${WISECONNECT_DIR}/components/device/silabs/si91x/mcu/drivers/systemlevel/src/rsi_ulpss_clk.c
   ${WISECONNECT_DIR}/components/device/silabs/si91x/mcu/drivers/systemlevel/src/rsi_wwdt.c
+  ${WISECONNECT_DIR}/components/device/silabs/si91x/mcu/drivers/systemlevel/src/rsi_rtc.c
+  ${WISECONNECT_DIR}/components/device/silabs/si91x/mcu/drivers/systemlevel/src/rsi_time_period.c
   ${WISECONNECT_DIR}/components/device/silabs/si91x/mcu/drivers/service/clock_manager/src/sl_si91x_clock_manager.c
+  ${WISECONNECT_DIR}/components/device/silabs/si91x/mcu/drivers/unified_api/src/sl_si91x_calendar.c
   ${WISECONNECT_DIR}/components/device/silabs/si91x/mcu/drivers/unified_api/src/sl_si91x_driver_gpio.c
   ${WISECONNECT_DIR}/components/device/silabs/si91x/mcu/drivers/unified_api/src/sl_si91x_pwm.c
   ${WISECONNECT_DIR}/components/device/silabs/si91x/mcu/drivers/unified_peripheral_drivers/src/sl_si91x_peripheral_gpio.c