drivers: Add mdio API

This commit adds support for MDIO bus. The bus is used by Ethernet
MACs to communicate with PHYs.

Signed-off-by: Arvin Farahmand <arvinf@ip-logix.com>

include/drivers/mdio.h

@@ -0,0 +1,158 @@
+/**
+ * @file
+ *
+ * @brief Public APIs for MDIO drivers.
+ */
+
+/*
+ * Copyright (c) 2021 IP-Logix Inc.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#ifndef ZEPHYR_INCLUDE_DRIVERS_MDIO_H_
+#define ZEPHYR_INCLUDE_DRIVERS_MDIO_H_
+
+/**
+ * @brief MDIO Interface
+ * @defgroup mdio_interface MDIO Interface
+ * @ingroup io_interfaces
+ * @{
+ */
+#include <zephyr/types.h>
+#include <device.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @cond INTERNAL_HIDDEN
+ *
+ * These are for internal use only, so skip these in
+ * public documentation.
+ */
+
+/** Order of items in this enum must match the `protocol` dts binding */
+enum MDIO_PROTOCOL {
+	CLAUSE_22	= 0,
+	CLAUSE_45	= 1,
+	MICREL_SMI	= 2,
+};
+
+__subsystem struct mdio_driver_api {
+	/** Enable the MDIO bus device */
+	void (*bus_enable)(const struct device *dev);
+
+	/** Disable the MDIO bus device */
+	void (*bus_disable)(const struct device *dev);
+
+	/** Read data from MDIO bus */
+	int (*read)(const struct device *dev, uint8_t prtad, uint8_t devad,
+		    uint16_t *data);
+
+	/** Write data to MDIO bus */
+	int (*write)(const struct device *dev, uint8_t prtad, uint8_t devad,
+		     uint16_t data);
+};
+/**
+ * @endcond
+ */
+
+/**
+ * @brief      Enable MDIO bus
+ *
+ * @param[in]  dev   Pointer to the device structure for the controller
+ *
+ */
+__syscall void mdio_bus_enable(const struct device *dev);
+
+static inline void z_impl_mdio_bus_enable(const struct device *dev)
+{
+	const struct mdio_driver_api *api =
+		(const struct mdio_driver_api *)dev->api;
+
+	return api->bus_enable(dev);
+}
+
+/**
+ * @brief      Disable MDIO bus and tri-state drivers
+ *
+ * @param[in]  dev   Pointer to the device structure for the controller
+ *
+ */
+__syscall void mdio_bus_disable(const struct device *dev);
+
+static inline void z_impl_mdio_bus_disable(const struct device *dev)
+{
+	const struct mdio_driver_api *api =
+		(const struct mdio_driver_api *)dev->api;
+
+	return api->bus_disable(dev);
+}
+
+/**
+ * @brief      Read from MDIO Bus
+ *
+ * This routine provides a generic interface to perform a read on the
+ * MDIO bus.
+ *
+ * @param[in]  dev         Pointer to the device structure for the controller
+ * @param[in]  prtad       Port address
+ * @param[in]  devad       Device address
+ * @param      data        Pointer to receive read data
+ *
+ * @retval 0 If successful.
+ * @retval -EIO General input / output error.
+ * @retval -ETIMEDOUT If transaction timedout on the bus
+ */
+__syscall int mdio_read(const struct device *dev, uint8_t prtad, uint8_t devad,
+			uint16_t *data);
+
+static inline int z_impl_mdio_read(const struct device *dev, uint8_t prtad,
+				   uint8_t devad, uint16_t *data)
+{
+	const struct mdio_driver_api *api =
+		(const struct mdio_driver_api *)dev->api;
+
+	return api->read(dev, prtad, devad, data);
+}
+
+
+/**
+ * @brief      Write to MDIO bus
+ *
+ * This routine provides a generic interface to perform a write on the
+ * MDIO bus.
+ *
+ * @param[in]  dev         Pointer to the device structure for the controller
+ * @param[in]  prtad       Port address
+ * @param[in]  devad       Device address
+ * @param[in]  data        Data to write
+ *
+ * @retval 0 If successful.
+ * @retval -EIO General input / output error.
+ * @retval -ETIMEDOUT If transaction timedout on the bus
+ */
+__syscall int mdio_write(const struct device *dev, uint8_t prtad, uint8_t devad,
+			 uint16_t data);
+
+static inline int z_impl_mdio_write(const struct device *dev, uint8_t prtad,
+				    uint8_t devad, uint16_t data)
+{
+	const struct mdio_driver_api *api =
+		(const struct mdio_driver_api *)dev->api;
+
+	return api->write(dev, prtad, devad, data);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+/**
+ * @}
+ */
+
+#include <syscalls/mdio.h>
+
+#endif /* ZEPHYR_INCLUDE_DRIVERS_MDIO_H_ */