--- /dev/null
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/* Copyright (c) 2015, The Linux Foundation. All rights reserved. */
+/* Copyright (c) 2020 Sartura Ltd. */
+
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/of_address.h>
+#include <linux/of_mdio.h>
+#include <linux/phy.h>
+#include <linux/platform_device.h>
+
+#define MDIO_ADDR_REG 0x44
+#define MDIO_DATA_WRITE_REG 0x48
+#define MDIO_DATA_READ_REG 0x4c
+#define MDIO_CMD_REG 0x50
+#define MDIO_CMD_ACCESS_BUSY BIT(16)
+#define MDIO_CMD_ACCESS_START BIT(8)
+#define MDIO_CMD_ACCESS_CODE_READ 0
+#define MDIO_CMD_ACCESS_CODE_WRITE 1
+
+#define ipq4019_MDIO_TIMEOUT 10000
+#define ipq4019_MDIO_SLEEP 10
+
+struct ipq4019_mdio_data {
+ void __iomem *membase;
+};
+
+static int ipq4019_mdio_wait_busy(struct mii_bus *bus)
+{
+ struct ipq4019_mdio_data *priv = bus->priv;
+ unsigned int busy;
+
+ return readl_poll_timeout(priv->membase + MDIO_CMD_REG, busy,
+ (busy & MDIO_CMD_ACCESS_BUSY) == 0,
+ ipq4019_MDIO_SLEEP, ipq4019_MDIO_TIMEOUT);
+}
+
+static int ipq4019_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
+{
+ struct ipq4019_mdio_data *priv = bus->priv;
+ unsigned int cmd;
+
+ /* Reject clause 45 */
+ if (regnum & MII_ADDR_C45)
+ return -EOPNOTSUPP;
+
+ if (ipq4019_mdio_wait_busy(bus))
+ return -ETIMEDOUT;
+
+ /* issue the phy address and reg */
+ writel((mii_id << 8) | regnum, priv->membase + MDIO_ADDR_REG);
+
+ cmd = MDIO_CMD_ACCESS_START | MDIO_CMD_ACCESS_CODE_READ;
+
+ /* issue read command */
+ writel(cmd, priv->membase + MDIO_CMD_REG);
+
+ /* Wait read complete */
+ if (ipq4019_mdio_wait_busy(bus))
+ return -ETIMEDOUT;
+
+ /* Read and return data */
+ return readl(priv->membase + MDIO_DATA_READ_REG);
+}
+
+static int ipq4019_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
+ u16 value)
+{
+ struct ipq4019_mdio_data *priv = bus->priv;
+ unsigned int cmd;
+
+ /* Reject clause 45 */
+ if (regnum & MII_ADDR_C45)
+ return -EOPNOTSUPP;
+
+ if (ipq4019_mdio_wait_busy(bus))
+ return -ETIMEDOUT;
+
+ /* issue the phy address and reg */
+ writel((mii_id << 8) | regnum, priv->membase + MDIO_ADDR_REG);
+
+ /* issue write data */
+ writel(value, priv->membase + MDIO_DATA_WRITE_REG);
+
+ cmd = MDIO_CMD_ACCESS_START | MDIO_CMD_ACCESS_CODE_WRITE;
+ /* issue write command */
+ writel(cmd, priv->membase + MDIO_CMD_REG);
+
+ /* Wait write complete */
+ if (ipq4019_mdio_wait_busy(bus))
+ return -ETIMEDOUT;
+
+ return 0;
+}
+
+static int ipq4019_mdio_probe(struct platform_device *pdev)
+{
+ struct ipq4019_mdio_data *priv;
+ struct mii_bus *bus;
+ int ret;
+
+ bus = devm_mdiobus_alloc_size(&pdev->dev, sizeof(*priv));
+ if (!bus)
+ return -ENOMEM;
+
+ priv = bus->priv;
+
+ priv->membase = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(priv->membase))
+ return PTR_ERR(priv->membase);
+
+ bus->name = "ipq4019_mdio";
+ bus->read = ipq4019_mdio_read;
+ bus->write = ipq4019_mdio_write;
+ bus->parent = &pdev->dev;
+ snprintf(bus->id, MII_BUS_ID_SIZE, "%s%d", pdev->name, pdev->id);
+
+ ret = of_mdiobus_register(bus, pdev->dev.of_node);
+ if (ret) {
+ dev_err(&pdev->dev, "Cannot register MDIO bus!\n");
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, bus);
+
+ return 0;
+}
+
+static int ipq4019_mdio_remove(struct platform_device *pdev)
+{
+ struct mii_bus *bus = platform_get_drvdata(pdev);
+
+ mdiobus_unregister(bus);
+
+ return 0;
+}
+
+static const struct of_device_id ipq4019_mdio_dt_ids[] = {
+ { .compatible = "qcom,ipq4019-mdio" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, ipq4019_mdio_dt_ids);
+
+static struct platform_driver ipq4019_mdio_driver = {
+ .probe = ipq4019_mdio_probe,
+ .remove = ipq4019_mdio_remove,
+ .driver = {
+ .name = "ipq4019-mdio",
+ .of_match_table = ipq4019_mdio_dt_ids,
+ },
+};
+
+module_platform_driver(ipq4019_mdio_driver);
+
+MODULE_DESCRIPTION("ipq4019 MDIO interface driver");
+MODULE_AUTHOR("Qualcomm Atheros");
+MODULE_LICENSE("Dual BSD/GPL");