drivers: mfd: add FLEXCOM drivers for Microchip SAM devices

The FLEXCOM offers several serial communication protocols that are
managed by the three sub-modules USART, SPI, and TWI (I2C).

Signed-off-by: Tony Han <tony.han@microchip.com>

drivers/mfd/CMakeLists.txt

@@ -23,4 +23,5 @@ zephyr_library_sources_ifdef(CONFIG_MFD_ITE_IT8801_ALTCTRL mfd_it8801_altctrl.c)
 zephyr_library_sources_ifdef(CONFIG_MFD_AW9523B mfd_aw9523b.c)
 zephyr_library_sources_ifdef(CONFIG_MFD_DS3231 mfd_ds3231.c)
 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)

drivers/mfd/Kconfig

@@ -28,6 +28,7 @@ source "drivers/mfd/Kconfig.max20335"
 source "drivers/mfd/Kconfig.max22017"
 source "drivers/mfd/Kconfig.max31790"
 source "drivers/mfd/Kconfig.maxq10xx"
+source "drivers/mfd/Kconfig.mchp_sam"
 source "drivers/mfd/Kconfig.nct38xx"
 source "drivers/mfd/Kconfig.npm1300"
 source "drivers/mfd/Kconfig.npm2100"

drivers/mfd/Kconfig.mchp_sam

@@ -0,0 +1,10 @@
+# Copyright (C) 2025 Microchip Technology Inc. and its subsidiaries
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config MFD_MCHP_SAM_FLEXCOM
+	bool "Driver for the Microchip SAM FLEXCOM Interface"
+	default y
+	depends on DT_HAS_MICROCHIP_SAM_FLEXCOM_ENABLED
+	help
+	  Enabled the SAM FLEXCOM driver.

drivers/mfd/mfd_mchp_sam_flexcom.c

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2025 Microchip Technology Inc. and its subsidiaries
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT microchip_sam_flexcom
+
+#include <errno.h>
+#include <zephyr/device.h>
+#include <zephyr/kernel.h>
+
+#include <zephyr/logging/log.h>
+LOG_MODULE_REGISTER(mfd_flexcomm, CONFIG_MFD_LOG_LEVEL);
+
+struct sam_flexcomm_config {
+	flexcom_registers_t *reg;
+	const int mode;
+};
+
+static int sam_flexcomm_init(const struct device *dev)
+{
+	const struct sam_flexcomm_config *config = dev->config;
+
+	config->reg->FLEX_MR = (config->reg->FLEX_MR & ~FLEX_MR_OPMODE_Msk) |
+			       FLEX_MR_OPMODE(config->mode);
+
+	LOG_DBG("%s set Operating Mode to %d", dev->name, config->mode);
+
+	return 0;
+}
+
+#define SAM_FLEXCOMM_INIT(n)							\
+										\
+	static const struct sam_flexcomm_config sam_flexcomm_config_##n = {	\
+		.reg = (flexcom_registers_t *)DT_INST_REG_ADDR(n),		\
+		.mode = DT_INST_PROP(n, mchp_flexcom_mode),			\
+	};									\
+										\
+	DEVICE_DT_INST_DEFINE(n,						\
+			      &sam_flexcomm_init,				\
+			      NULL,						\
+			      NULL,						\
+			      &sam_flexcomm_config_##n,				\
+			      PRE_KERNEL_1,					\
+			      CONFIG_KERNEL_INIT_PRIORITY_DEFAULT,		\
+			      NULL);						\
+
+DT_INST_FOREACH_STATUS_OKAY(SAM_FLEXCOMM_INIT)

dts/bindings/mfd/microchip,sam-flexcom.yaml

@@ -0,0 +1,25 @@
+# Copyright (C) 2025 Microchip Technology Inc. and its subsidiaries
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+description: Microchip Flexcom (Flexible Serial Communication Unit)
+
+compatible: "microchip,sam-flexcom"
+
+include: base.yaml
+
+properties:
+  reg:
+    required: true
+
+  mchp,flexcom-mode:
+    type: int
+    description: Initial operating mode for FLEXCOM
+
+  "#address-cells":
+    required: true
+    const: 1
+  "#size-cells":
+    required: true
+    const: 1

include/zephyr/dt-bindings/mfd/mfd_mchp_sam_flexcom.h

@@ -0,0 +1,17 @@
+/*
+ * Copyright (C) 2025 Microchip Technology Inc. and its subsidiaries
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#ifndef ZEPHYR_INCLUDE_DT_BINDINGS_MFD_MCHP_SAM_FLEXCOMM_H_
+#define ZEPHYR_INCLUDE_DT_BINDINGS_MFD_MCHP_SAM_FLEXCOMM_H_
+
+/**
+ * @brief FLEXCOM Operating Mode.
+ */
+#define SAM_FLEXCOM_MODE_NO_COM 0
+#define SAM_FLEXCOM_MODE_USART  1
+#define SAM_FLEXCOM_MODE_SPI    2
+#define SAM_FLEXCOM_MODE_TWI    3
+
+#endif /* ZEPHYR_INCLUDE_DT_BINDINGS_MFD_MCHP_SAM_FLEXCOMM_H_ */