// SPDX-License-Identifier: GPL-2.0

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_mdio.h>
#include <linux/phy.h>
#include <linux/usb.h>

#define USB_MARVELL_VID 0x1286

static const struct usb_device_id mvusb_mdio_table[] = {
        { USB_DEVICE(USB_MARVELL_VID, 0x1fa4) },

        {}
};
MODULE_DEVICE_TABLE(usb, mvusb_mdio_table);

enum {
        MVUSB_CMD_PREAMBLE0,
        MVUSB_CMD_PREAMBLE1,
        MVUSB_CMD_ADDR,
        MVUSB_CMD_VAL,
};

struct mvusb_mdio {
        struct usb_device *udev;
        struct mii_bus *mdio;

        __le16 buf[4];
};

static int mvusb_mdio_read(struct mii_bus *mdio, int dev, int reg)
{
        struct mvusb_mdio *mvusb = mdio->priv;
        int err, alen;

        mvusb->buf[MVUSB_CMD_ADDR] = cpu_to_le16(0xa400 | (dev << 5) | reg);

        err = usb_bulk_msg(mvusb->udev, usb_sndbulkpipe(mvusb->udev, 2),
                           mvusb->buf, 6, &alen, 100);
        if (err)
                return err;

        err = usb_bulk_msg(mvusb->udev, usb_rcvbulkpipe(mvusb->udev, 6),
                           &mvusb->buf[MVUSB_CMD_VAL], 2, &alen, 100);
        if (err)
                return err;

        return le16_to_cpu(mvusb->buf[MVUSB_CMD_VAL]);
}

static int mvusb_mdio_write(struct mii_bus *mdio, int dev, int reg, u16 val)
{
        struct mvusb_mdio *mvusb = mdio->priv;
        int alen;

        mvusb->buf[MVUSB_CMD_ADDR] = cpu_to_le16(0x8000 | (dev << 5) | reg);
        mvusb->buf[MVUSB_CMD_VAL]  = cpu_to_le16(val);

        return usb_bulk_msg(mvusb->udev, usb_sndbulkpipe(mvusb->udev, 2),
                            mvusb->buf, 8, &alen, 100);
}

static int mvusb_mdio_probe(struct usb_interface *interface,
                            const struct usb_device_id *id)
{
        struct device *dev = &interface->dev;
        struct mvusb_mdio *mvusb;
        struct mii_bus *mdio;
        int ret;

        mdio = devm_mdiobus_alloc_size(dev, sizeof(*mvusb));
        if (!mdio)
                return -ENOMEM;

        mvusb = mdio->priv;
        mvusb->mdio = mdio;
        mvusb->udev = usb_get_dev(interface_to_usbdev(interface));

        /* Reversed from USB PCAPs, no idea what these mean. */
        mvusb->buf[MVUSB_CMD_PREAMBLE0] = cpu_to_le16(0xe800);
        mvusb->buf[MVUSB_CMD_PREAMBLE1] = cpu_to_le16(0x0001);

        snprintf(mdio->id, MII_BUS_ID_SIZE, "mvusb-%s", dev_name(dev));
        mdio->name = mdio->id;
        mdio->parent = dev;
        mdio->read = mvusb_mdio_read;
        mdio->write = mvusb_mdio_write;

        usb_set_intfdata(interface, mvusb);
        ret = of_mdiobus_register(mdio, dev->of_node);
        if (ret)
                goto put_dev;

        return 0;

put_dev:
        usb_put_dev(mvusb->udev);
        return ret;
}

static void mvusb_mdio_disconnect(struct usb_interface *interface)
{
        struct mvusb_mdio *mvusb = usb_get_intfdata(interface);
        struct usb_device *udev = mvusb->udev;

        mdiobus_unregister(mvusb->mdio);
        usb_set_intfdata(interface, NULL);
        usb_put_dev(udev);
}

static struct usb_driver mvusb_mdio_driver = {
        .name       = "mvusb_mdio",
        .id_table   = mvusb_mdio_table,
        .probe      = mvusb_mdio_probe,
        .disconnect = mvusb_mdio_disconnect,
};

module_usb_driver(mvusb_mdio_driver);

MODULE_AUTHOR("Tobias Waldekranz <tobias@waldekranz.com>");
MODULE_DESCRIPTION("Marvell USB MDIO Adapter");
MODULE_LICENSE("GPL");