drivers: mfd: Enabled motorola,mc146818 MFD

Enabled Motorola, mc146818 MFD, which implements RTC
read/write operations and prevents data corruption
by synchronizing these operations.

Signed-off-by: Anisetti Avinash Krishna <anisetti.avinash.krishna@intel.com>

drivers/mfd/CMakeLists.txt

@@ -26,3 +26,4 @@ zephyr_library_sources_ifdef(CONFIG_MFD_MAX22017 mfd_max22017.c)
 zephyr_library_sources_ifdef(CONFIG_MFD_MCHP_SAM_FLEXCOM mfd_mchp_sam_flexcom.c)
 zephyr_library_sources_ifdef(CONFIG_MFD_PF1550 mfd_pf1550.c)
 zephyr_library_sources_ifdef(CONFIG_MFD_PCA9422 mfd_pca9422.c)
+zephyr_library_sources_ifdef(CONFIG_MFD_MOTOROLA_MC146818 mfd_mc146818.c)

drivers/mfd/Kconfig

@@ -38,5 +38,6 @@ source "drivers/mfd/Kconfig.lpflexcomm"
 source "drivers/mfd/Kconfig.tle9104"
 source "drivers/mfd/Kconfig.it8801"
 source "drivers/mfd/Kconfig.pca9422"
+source "drivers/mfd/Kconfig.mc146818"
 
 endif # MFD

drivers/mfd/Kconfig.mc146818

@@ -0,0 +1,20 @@
+# Intel SoC RTC configuration options
+
+# Copyright (c) 2025 Intel Corporation
+# SPDX-License-Identifier: Apache-2.0
+
+config MFD_MOTOROLA_MC146818
+	bool "MOTOROLA MC146818 multi-function device driver"
+	default y
+	depends on DT_HAS_MOTOROLA_MC146818_MFD_ENABLED
+	help
+	  common code required by bbram and rtc, which will likely be a locking mechanism
+	  so both RTC and BBRAM can set/get regs safely and independently.
+
+config MFD_MOTOROLA_MC146818_INIT_PRIORITY
+	int "Init priority of mc146818 MFD"
+	depends on MFD_MOTOROLA_MC146818
+	default 50
+	help
+	  Initialization priority for the MOTOROLA MC146818 MFD driver.
+	  It must be greater than RTC, COUNTER and BBRAM driver init priority.

drivers/mfd/mfd_mc146818.c

@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2025 Intel Corporation.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT motorola_mc146818_mfd
+
+#include <zephyr/kernel.h>
+#include <zephyr/device.h>
+#include <zephyr/spinlock.h>
+#include <zephyr/drivers/mfd/mc146818.h>
+#include <zephyr/init.h>
+#include <zephyr/sys/util.h>
+#include <zephyr/devicetree.h>
+#include <zephyr/sys/sys_io.h>
+
+#define RTC_STD_INDEX (DT_INST_REG_ADDR_BY_IDX(0, 0))
+#define RTC_STD_TARGET (DT_INST_REG_ADDR_BY_IDX(0, 1))
+#define RTC_EXT_INDEX (DT_INST_REG_ADDR_BY_IDX(0, 2))
+#define RTC_EXT_TARGET (DT_INST_REG_ADDR_BY_IDX(0, 3))
+
+struct mfd_mc146818_data {
+	struct k_spinlock lock;
+};
+
+uint8_t mfd_mc146818_std_read(const struct device *dev, uint8_t offset)
+{
+	struct mfd_mc146818_data *data = dev->data;
+	uint8_t value;
+
+	k_spinlock_key_t key = k_spin_lock(&data->lock);
+
+	sys_out8(offset, RTC_STD_INDEX);
+	value = sys_in8(RTC_STD_TARGET);
+
+	k_spin_unlock(&data->lock, key);
+	return value;
+}
+
+void mfd_mc146818_std_write(const struct device *dev, uint8_t offset, uint8_t value)
+{
+	struct mfd_mc146818_data *data = dev->data;
+
+	k_spinlock_key_t key = k_spin_lock(&data->lock);
+
+	sys_out8(offset, RTC_STD_INDEX);
+	sys_out8(value, RTC_STD_TARGET);
+
+	k_spin_unlock(&data->lock, key);
+}
+
+uint8_t mfd_mc146818_ext_read(const struct device *dev, uint8_t offset)
+{
+	struct mfd_mc146818_data *data = dev->data;
+	uint8_t value;
+
+	k_spinlock_key_t key = k_spin_lock(&data->lock);
+
+	sys_out8(offset, RTC_EXT_INDEX);
+	value = sys_in8(RTC_EXT_TARGET);
+
+	k_spin_unlock(&data->lock, key);
+	return value;
+}
+
+void mfd_mc146818_ext_write(const struct device *dev, uint8_t offset, uint8_t value)
+{
+	struct mfd_mc146818_data *data = dev->data;
+
+	k_spinlock_key_t key = k_spin_lock(&data->lock);
+
+	sys_out8(offset, RTC_EXT_INDEX);
+	sys_out8(value, RTC_EXT_TARGET);
+
+	k_spin_unlock(&data->lock, key);
+}
+
+#define MFD_MC146818_DEFINE(inst)						\
+	static struct mfd_mc146818_data data##inst;				\
+	DEVICE_DT_INST_DEFINE(inst, NULL, NULL, &data##inst, NULL,		\
+			      POST_KERNEL,					\
+			      CONFIG_MFD_MOTOROLA_MC146818_INIT_PRIORITY,	\
+			      NULL);						\
+
+DT_INST_FOREACH_STATUS_OKAY(MFD_MC146818_DEFINE)

dts/bindings/mfd/motorola,mc146818-mfd.yaml

@@ -0,0 +1,34 @@
+# Copyright (c) 2025, Intel Corporation
+#
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+  Motorola MC146818 MFD
+
+  The following example displays the node layout
+  with every possible partial driver included.
+
+  mfd: mfd@70 {
+    compatible = "motorola,mc146818-mfd";
+    reg = <0x70 0x01 0x71 0x01 0x72 0x01 0x73 0x01>;
+    rtc: counter: rtc {
+      compatible = "motorola,mc146818";
+      interrupts = <8 IRQ_TYPE_LOWEST_EDGE_RISING 3>;
+      interrupt-parent = <&intc>;
+      alarms-count = <1>;
+
+      status = "okay";
+    };
+
+    bbram: bbram {
+      compatible = "motorola,mc146818-bbram";
+      size = <241>;
+      status = "okay";
+    };
+  };
+
+compatible: "motorola,mc146818-mfd"
+
+include: base.yaml
+
+bus: mc146818-mfd

include/zephyr/drivers/mfd/mc146818.h

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2025 Intel Corporation.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_DRIVERS_MFD_MC146818_H_
+#define ZEPHYR_INCLUDE_DRIVERS_MFD_MC146818_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <zephyr/device.h>
+
+/**
+ * @brief Read the value at the given offset in standard memory bank.
+ *
+ * @param dev mc146818 mfd device
+ * @param offset memory offset to be read.
+ * @retval value at the offset
+ */
+uint8_t mfd_mc146818_std_read(const struct device *dev, uint8_t offset);
+
+/**
+ * @brief Write the value at the given offset in standard memory bank.
+ *
+ * @param dev mc146818 mfd device
+ * @param offset memory offset to be written.
+ * @param value to be written at the offset
+ */
+void mfd_mc146818_std_write(const struct device *dev, uint8_t offset, uint8_t value);
+
+/**
+ * @brief Read the value at the given offset in extended memory bank.
+ *
+ * @param dev mc146818 mfd device
+ * @param offset memory offset to be read.
+ * @retval value at the offset
+ */
+uint8_t mfd_mc146818_ext_read(const struct device *dev, uint8_t offset);
+
+/**
+ * @brief Write the value at the given offset in extended memory bank.
+ *
+ * @param dev mc146818 mfd device
+ * @param offset memory offset to be written.
+ * @param value to be written at the offset
+ */
+void mfd_mc146818_ext_write(const struct device *dev, uint8_t offset, uint8_t value);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZEPHYR_INCLUDE_DRIVERS_MFD_MC146818_H_ */