--- /dev/null
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2019
+ * Alex Marginean, NXP
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <miiphy.h>
+#include <dm/device-internal.h>
+#include <dm/uclass-internal.h>
+#include <dm/lists.h>
+
+#define MDIO_MUX_CHILD_DRV_NAME "mdio-mux-bus-drv"
+
+/**
+ * struct mdio_mux_perdev_priv - Per-device class data for MDIO MUX DM
+ *
+ * @parent_mdio: Parent DM MDIO device, this is called for actual MDIO I/O after
+ * setting up the mux. Typically this is a real MDIO device,
+ * unless there are cascaded muxes.
+ * @selected: Current child bus selection. Defaults to -1
+ */
+struct mdio_mux_perdev_priv {
+ struct udevice *mdio_parent;
+ int selected;
+};
+
+/*
+ * This source file uses three types of devices, as follows:
+ * - mux is the hardware MDIO MUX which selects between the existing child MDIO
+ * buses, this is the device relevant for MDIO MUX class of drivers.
+ * - ch is a child MDIO bus, this is just a representation of a mux selection,
+ * not a real piece of hardware.
+ * - mdio_parent is the actual MDIO bus called to perform reads/writes after
+ * the MUX is configured. Typically this is a real MDIO device, unless there
+ * are cascaded muxes.
+ */
+
+/**
+ * struct mdio_mux_ch_data - Per-device data for child MDIOs
+ *
+ * @sel: Selection value used by the MDIO MUX to access this child MDIO bus
+ */
+struct mdio_mux_ch_data {
+ int sel;
+};
+
+static struct udevice *mmux_get_parent_mdio(struct udevice *mux)
+{
+ struct mdio_mux_perdev_priv *pdata = dev_get_uclass_priv(mux);
+
+ return pdata->mdio_parent;
+}
+
+static struct mdio_ops *mmux_get_mdio_parent_ops(struct udevice *mux)
+{
+ return mdio_get_ops(mmux_get_parent_mdio(mux));
+}
+
+/* call driver select function before performing MDIO r/w */
+static int mmux_change_sel(struct udevice *ch, bool sel)
+{
+ struct udevice *mux = ch->parent;
+ struct mdio_mux_perdev_priv *priv = dev_get_uclass_priv(mux);
+ struct mdio_mux_ops *ops = mdio_mux_get_ops(mux);
+ struct mdio_mux_ch_data *ch_data = dev_get_parent_platdata(ch);
+ int err = 0;
+
+ if (sel) {
+ err = ops->select(mux, priv->selected, ch_data->sel);
+ if (err)
+ return err;
+
+ priv->selected = ch_data->sel;
+ } else {
+ if (ops->deselect) {
+ ops->deselect(mux, ch_data->sel);
+ priv->selected = MDIO_MUX_SELECT_NONE;
+ }
+ }
+
+ return 0;
+}
+
+/* Read wrapper, sets up the mux before issuing a read on parent MDIO bus */
+static int mmux_read(struct udevice *ch, int addr, int devad,
+ int reg)
+{
+ struct udevice *mux = ch->parent;
+ struct udevice *parent_mdio = mmux_get_parent_mdio(mux);
+ struct mdio_ops *parent_ops = mmux_get_mdio_parent_ops(mux);
+ int err;
+
+ err = mmux_change_sel(ch, true);
+ if (err)
+ return err;
+
+ err = parent_ops->read(parent_mdio, addr, devad, reg);
+ mmux_change_sel(ch, false);
+
+ return err;
+}
+
+/* Write wrapper, sets up the mux before issuing a write on parent MDIO bus */
+static int mmux_write(struct udevice *ch, int addr, int devad,
+ int reg, u16 val)
+{
+ struct udevice *mux = ch->parent;
+ struct udevice *parent_mdio = mmux_get_parent_mdio(mux);
+ struct mdio_ops *parent_ops = mmux_get_mdio_parent_ops(mux);
+ int err;
+
+ err = mmux_change_sel(ch, true);
+ if (err)
+ return err;
+
+ err = parent_ops->write(parent_mdio, addr, devad, reg, val);
+ mmux_change_sel(ch, false);
+
+ return err;
+}
+
+/* Reset wrapper, sets up the mux before issuing a reset on parent MDIO bus */
+static int mmux_reset(struct udevice *ch)
+{
+ struct udevice *mux = ch->parent;
+ struct udevice *parent_mdio = mmux_get_parent_mdio(mux);
+ struct mdio_ops *parent_ops = mmux_get_mdio_parent_ops(mux);
+ int err;
+
+ /* reset is optional, if it's not implemented just exit */
+ if (!parent_ops->reset)
+ return 0;
+
+ err = mmux_change_sel(ch, true);
+ if (err)
+ return err;
+
+ err = parent_ops->reset(parent_mdio);
+ mmux_change_sel(ch, false);
+
+ return err;
+}
+
+/* Picks up the mux selection value for each child */
+static int dm_mdio_mux_child_post_bind(struct udevice *ch)
+{
+ struct mdio_mux_ch_data *ch_data = dev_get_parent_platdata(ch);
+
+ ch_data->sel = dev_read_u32_default(ch, "reg", MDIO_MUX_SELECT_NONE);
+
+ if (ch_data->sel == MDIO_MUX_SELECT_NONE)
+ return -EINVAL;
+
+ return 0;
+}
+
+/* Explicitly bind child MDIOs after binding the mux */
+static int dm_mdio_mux_post_bind(struct udevice *mux)
+{
+ ofnode ch_node;
+ int err, first_err = 0;
+
+ if (!ofnode_valid(mux->node)) {
+ debug("%s: no mux node found, no child MDIO busses set up\n",
+ __func__);
+ return 0;
+ }
+
+ /*
+ * we're going by Linux bindings so the child nodes do not have
+ * compatible strings. We're going through them here and binding to
+ * them.
+ */
+ dev_for_each_subnode(ch_node, mux) {
+ struct udevice *ch_dev;
+ const char *ch_name;
+
+ ch_name = ofnode_get_name(ch_node);
+
+ err = device_bind_driver_to_node(mux, MDIO_MUX_CHILD_DRV_NAME,
+ ch_name, ch_node, &ch_dev);
+ /* try to bind all, but keep 1st error */
+ if (err && !first_err)
+ first_err = err;
+ }
+
+ return first_err;
+}
+
+/* Get a reference to the parent MDIO bus, it should be bound by now */
+static int dm_mdio_mux_post_probe(struct udevice *mux)
+{
+ struct mdio_mux_perdev_priv *priv = dev_get_uclass_priv(mux);
+ int err;
+
+ priv->selected = MDIO_MUX_SELECT_NONE;
+
+ /* pick up mdio parent from device tree */
+ err = uclass_get_device_by_phandle(UCLASS_MDIO, mux, "mdio-parent-bus",
+ &priv->mdio_parent);
+ if (err) {
+ debug("%s: didn't find mdio-parent-bus\n", __func__);
+ return err;
+ }
+
+ return 0;
+}
+
+const struct mdio_ops mmux_child_mdio_ops = {
+ .read = mmux_read,
+ .write = mmux_write,
+ .reset = mmux_reset,
+};
+
+/* MDIO class driver used for MUX child MDIO buses */
+U_BOOT_DRIVER(mdio_mux_child) = {
+ .name = MDIO_MUX_CHILD_DRV_NAME,
+ .id = UCLASS_MDIO,
+ .ops = &mmux_child_mdio_ops,
+};
+
+UCLASS_DRIVER(mdio_mux) = {
+ .id = UCLASS_MDIO_MUX,
+ .name = "mdio-mux",
+ .child_post_bind = dm_mdio_mux_child_post_bind,
+ .post_bind = dm_mdio_mux_post_bind,
+ .post_probe = dm_mdio_mux_post_probe,
+ .per_device_auto_alloc_size = sizeof(struct mdio_mux_perdev_priv),
+ .per_child_platdata_auto_alloc_size = sizeof(struct mdio_mux_ch_data),
+};
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