--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Microchip KSZ8863 series register access through SMI
+ *
+ * Copyright (C) 2019 Pengutronix, Michael Grzeschik <kernel@pengutronix.de>
+ */
+
+#include "ksz8.h"
+#include "ksz_common.h"
+
+/* Serial Management Interface (SMI) uses the following frame format:
+ *
+ *       preamble|start|Read/Write|  PHY   |  REG  |TA|   Data bits      | Idle
+ *               |frame| OP code  |address |address|  |                  |
+ * read | 32x1´s | 01  |    00    | 1xRRR  | RRRRR |Z0| 00000000DDDDDDDD |  Z
+ * write| 32x1´s | 01  |    00    | 0xRRR  | RRRRR |10| xxxxxxxxDDDDDDDD |  Z
+ *
+ */
+
+#define SMI_KSZ88XX_READ_PHY   BIT(4)
+
+static int ksz8863_mdio_read(void *ctx, const void *reg_buf, size_t reg_len,
+                            void *val_buf, size_t val_len)
+{
+       struct ksz_device *dev = ctx;
+       struct mdio_device *mdev;
+       u8 reg = *(u8 *)reg_buf;
+       u8 *val = val_buf;
+       struct ksz8 *ksz8;
+       int i, ret = 0;
+
+       ksz8 = dev->priv;
+       mdev = ksz8->priv;
+
+       mutex_lock_nested(&mdev->bus->mdio_lock, MDIO_MUTEX_NESTED);
+       for (i = 0; i < val_len; i++) {
+               int tmp = reg + i;
+
+               ret = __mdiobus_read(mdev->bus, ((tmp & 0xE0) >> 5) |
+                                    SMI_KSZ88XX_READ_PHY, tmp);
+               if (ret < 0)
+                       goto out;
+
+               val[i] = ret;
+       }
+       ret = 0;
+
+ out:
+       mutex_unlock(&mdev->bus->mdio_lock);
+
+       return ret;
+}
+
+static int ksz8863_mdio_write(void *ctx, const void *data, size_t count)
+{
+       struct ksz_device *dev = ctx;
+       struct mdio_device *mdev;
+       struct ksz8 *ksz8;
+       int i, ret = 0;
+       u32 reg;
+       u8 *val;
+
+       ksz8 = dev->priv;
+       mdev = ksz8->priv;
+
+       val = (u8 *)(data + 4);
+       reg = *(u32 *)data;
+
+       mutex_lock_nested(&mdev->bus->mdio_lock, MDIO_MUTEX_NESTED);
+       for (i = 0; i < (count - 4); i++) {
+               int tmp = reg + i;
+
+               ret = __mdiobus_write(mdev->bus, ((tmp & 0xE0) >> 5),
+                                     tmp, val[i]);
+               if (ret < 0)
+                       goto out;
+       }
+
+ out:
+       mutex_unlock(&mdev->bus->mdio_lock);
+
+       return ret;
+}
+
+static const struct regmap_bus regmap_smi[] = {
+       {
+               .read = ksz8863_mdio_read,
+               .write = ksz8863_mdio_write,
+               .max_raw_read = 1,
+               .max_raw_write = 1,
+       },
+       {
+               .read = ksz8863_mdio_read,
+               .write = ksz8863_mdio_write,
+               .val_format_endian_default = REGMAP_ENDIAN_BIG,
+               .max_raw_read = 2,
+               .max_raw_write = 2,
+       },
+       {
+               .read = ksz8863_mdio_read,
+               .write = ksz8863_mdio_write,
+               .val_format_endian_default = REGMAP_ENDIAN_BIG,
+               .max_raw_read = 4,
+               .max_raw_write = 4,
+       }
+};
+
+static const struct regmap_config ksz8863_regmap_config[] = {
+       {
+               .name = "#8",
+               .reg_bits = 8,
+               .pad_bits = 24,
+               .val_bits = 8,
+               .cache_type = REGCACHE_NONE,
+               .use_single_read = 1,
+               .lock = ksz_regmap_lock,
+               .unlock = ksz_regmap_unlock,
+       },
+       {
+               .name = "#16",
+               .reg_bits = 8,
+               .pad_bits = 24,
+               .val_bits = 16,
+               .cache_type = REGCACHE_NONE,
+               .use_single_read = 1,
+               .lock = ksz_regmap_lock,
+               .unlock = ksz_regmap_unlock,
+       },
+       {
+               .name = "#32",
+               .reg_bits = 8,
+               .pad_bits = 24,
+               .val_bits = 32,
+               .cache_type = REGCACHE_NONE,
+               .use_single_read = 1,
+               .lock = ksz_regmap_lock,
+               .unlock = ksz_regmap_unlock,
+       }
+};
+
+static int ksz8863_smi_probe(struct mdio_device *mdiodev)
+{
+       struct regmap_config rc;
+       struct ksz_device *dev;
+       struct ksz8 *ksz8;
+       int ret;
+       int i;
+
+       ksz8 = devm_kzalloc(&mdiodev->dev, sizeof(struct ksz8), GFP_KERNEL);
+       ksz8->priv = mdiodev;
+
+       dev = ksz_switch_alloc(&mdiodev->dev, ksz8);
+       if (!dev)
+               return -EINVAL;
+
+       for (i = 0; i < ARRAY_SIZE(ksz8863_regmap_config); i++) {
+               rc = ksz8863_regmap_config[i];
+               rc.lock_arg = &dev->regmap_mutex;
+               dev->regmap[i] = devm_regmap_init(&mdiodev->dev,
+                                                 ®map_smi[i], dev,
+                                                 &rc);
+               if (IS_ERR(dev->regmap[i])) {
+                       ret = PTR_ERR(dev->regmap[i]);
+                       dev_err(&mdiodev->dev,
+                               "Failed to initialize regmap%i: %d\n",
+                               ksz8863_regmap_config[i].val_bits, ret);
+                       return ret;
+               }
+       }
+
+       if (mdiodev->dev.platform_data)
+               dev->pdata = mdiodev->dev.platform_data;
+
+       ret = ksz8_switch_register(dev);
+
+       /* Main DSA driver may not be started yet. */
+       if (ret)
+               return ret;
+
+       dev_set_drvdata(&mdiodev->dev, dev);
+
+       return 0;
+}
+
+static void ksz8863_smi_remove(struct mdio_device *mdiodev)
+{
+       struct ksz_device *dev = dev_get_drvdata(&mdiodev->dev);
+
+       if (dev)
+               ksz_switch_remove(dev);
+}
+
+static const struct of_device_id ksz8863_dt_ids[] = {
+       { .compatible = "microchip,ksz8863" },
+       { .compatible = "microchip,ksz8873" },
+       { },
+};
+MODULE_DEVICE_TABLE(of, ksz8863_dt_ids);
+
+static struct mdio_driver ksz8863_driver = {
+       .probe  = ksz8863_smi_probe,
+       .remove = ksz8863_smi_remove,
+       .mdiodrv.driver = {
+               .name   = "ksz8863-switch",
+               .of_match_table = ksz8863_dt_ids,
+       },
+};
+
+mdio_module_driver(ksz8863_driver);
+
+MODULE_AUTHOR("Michael Grzeschik <m.grzeschik@pengutronix.de>");
+MODULE_DESCRIPTION("Microchip KSZ8863 SMI Switch driver");
+MODULE_LICENSE("GPL v2");