root/drivers/usb/atm/xusbatm.c
// SPDX-License-Identifier: GPL-2.0+
/******************************************************************************
 *  xusbatm.c - dumb usbatm-based driver for modems initialized in userspace
 *
 *  Copyright (C) 2005 Duncan Sands, Roman Kagan (rkagan % mail ! ru)
 ******************************************************************************/

#include <linux/module.h>
#include <linux/etherdevice.h>          /* for eth_random_addr() */

#include "usbatm.h"


#define XUSBATM_DRIVERS_MAX     8

#define XUSBATM_PARM(name, type, parmtype, desc) \
        static type name[XUSBATM_DRIVERS_MAX]; \
        static unsigned int num_##name; \
        module_param_array(name, parmtype, &num_##name, 0444); \
        MODULE_PARM_DESC(name, desc)

XUSBATM_PARM(vendor, unsigned short, ushort, "USB device vendor");
XUSBATM_PARM(product, unsigned short, ushort, "USB device product");

XUSBATM_PARM(rx_endpoint, unsigned char, byte, "rx endpoint number");
XUSBATM_PARM(tx_endpoint, unsigned char, byte, "tx endpoint number");
XUSBATM_PARM(rx_padding, unsigned char, byte, "rx padding (default 0)");
XUSBATM_PARM(tx_padding, unsigned char, byte, "tx padding (default 0)");
XUSBATM_PARM(rx_altsetting, unsigned char, byte, "rx altsetting (default 0)");
XUSBATM_PARM(tx_altsetting, unsigned char, byte, "rx altsetting (default 0)");

static const char xusbatm_driver_name[] = "xusbatm";

static struct usbatm_driver xusbatm_drivers[XUSBATM_DRIVERS_MAX];
static struct usb_device_id xusbatm_usb_ids[XUSBATM_DRIVERS_MAX + 1];
static struct usb_driver xusbatm_usb_driver;

static struct usb_interface *xusbatm_find_intf(struct usb_device *usb_dev, int altsetting, u8 ep)
{
        struct usb_host_interface *alt;
        struct usb_interface *intf;
        int i, j;

        for (i = 0; i < usb_dev->actconfig->desc.bNumInterfaces; i++)
                if ((intf = usb_dev->actconfig->interface[i]) && (alt = usb_altnum_to_altsetting(intf, altsetting)))
                        for (j = 0; j < alt->desc.bNumEndpoints; j++)
                                if (alt->endpoint[j].desc.bEndpointAddress == ep)
                                        return intf;
        return NULL;
}

static int xusbatm_capture_intf(struct usbatm_data *usbatm, struct usb_device *usb_dev,
                struct usb_interface *intf, int altsetting, int claim)
{
        int ifnum = intf->altsetting->desc.bInterfaceNumber;
        int ret;

        if (claim && (ret = usb_driver_claim_interface(&xusbatm_usb_driver, intf, usbatm))) {
                usb_err(usbatm, "%s: failed to claim interface %2d (%d)!\n", __func__, ifnum, ret);
                return ret;
        }
        ret = usb_set_interface(usb_dev, ifnum, altsetting);
        if (ret) {
                usb_err(usbatm, "%s: altsetting %2d for interface %2d failed (%d)!\n", __func__, altsetting, ifnum, ret);
                return ret;
        }
        return 0;
}

static void xusbatm_release_intf(struct usb_device *usb_dev, struct usb_interface *intf, int claimed)
{
        if (claimed) {
                usb_set_intfdata(intf, NULL);
                usb_driver_release_interface(&xusbatm_usb_driver, intf);
        }
}

static int xusbatm_bind(struct usbatm_data *usbatm,
                        struct usb_interface *intf, const struct usb_device_id *id)
{
        struct usb_device *usb_dev = interface_to_usbdev(intf);
        int drv_ix = id - xusbatm_usb_ids;
        int rx_alt = rx_altsetting[drv_ix];
        int tx_alt = tx_altsetting[drv_ix];
        struct usb_interface *rx_intf = xusbatm_find_intf(usb_dev, rx_alt, rx_endpoint[drv_ix]);
        struct usb_interface *tx_intf = xusbatm_find_intf(usb_dev, tx_alt, tx_endpoint[drv_ix]);
        int ret;

        usb_dbg(usbatm, "%s: binding driver %d: vendor %04x product %04x"
                " rx: ep %02x padd %d alt %2d tx: ep %02x padd %d alt %2d\n",
                __func__, drv_ix, vendor[drv_ix], product[drv_ix],
                rx_endpoint[drv_ix], rx_padding[drv_ix], rx_alt,
                tx_endpoint[drv_ix], tx_padding[drv_ix], tx_alt);

        if (!rx_intf || !tx_intf) {
                if (!rx_intf)
                        usb_dbg(usbatm, "%s: no interface contains endpoint %02x in altsetting %2d\n",
                                __func__, rx_endpoint[drv_ix], rx_alt);
                if (!tx_intf)
                        usb_dbg(usbatm, "%s: no interface contains endpoint %02x in altsetting %2d\n",
                                __func__, tx_endpoint[drv_ix], tx_alt);
                return -ENODEV;
        }

        if ((rx_intf != intf) && (tx_intf != intf))
                return -ENODEV;

        if ((rx_intf == tx_intf) && (rx_alt != tx_alt)) {
                usb_err(usbatm, "%s: altsettings clash on interface %2d (%2d vs %2d)!\n", __func__,
                                rx_intf->altsetting->desc.bInterfaceNumber, rx_alt, tx_alt);
                return -EINVAL;
        }

        usb_dbg(usbatm, "%s: rx If#=%2d; tx If#=%2d\n", __func__,
                        rx_intf->altsetting->desc.bInterfaceNumber,
                        tx_intf->altsetting->desc.bInterfaceNumber);

        ret = xusbatm_capture_intf(usbatm, usb_dev, rx_intf, rx_alt, rx_intf != intf);
        if (ret)
                return ret;

        if ((tx_intf != rx_intf) && (ret = xusbatm_capture_intf(usbatm, usb_dev, tx_intf, tx_alt, tx_intf != intf))) {
                xusbatm_release_intf(usb_dev, rx_intf, rx_intf != intf);
                return ret;
        }

        return 0;
}

static void xusbatm_unbind(struct usbatm_data *usbatm,
                           struct usb_interface *intf)
{
        struct usb_device *usb_dev = interface_to_usbdev(intf);
        int i;

        usb_dbg(usbatm, "%s entered\n", __func__);

        for (i = 0; i < usb_dev->actconfig->desc.bNumInterfaces; i++) {
                struct usb_interface *cur_intf = usb_dev->actconfig->interface[i];

                if (cur_intf && (usb_get_intfdata(cur_intf) == usbatm)) {
                        usb_set_intfdata(cur_intf, NULL);
                        usb_driver_release_interface(&xusbatm_usb_driver, cur_intf);
                }
        }
}

static int xusbatm_atm_start(struct usbatm_data *usbatm,
                             struct atm_dev *atm_dev)
{
        atm_dbg(usbatm, "%s entered\n", __func__);

        /* use random MAC as we've no way to get it from the device */
        eth_random_addr(atm_dev->esi);

        return 0;
}


static int xusbatm_usb_probe(struct usb_interface *intf,
                             const struct usb_device_id *id)
{
        return usbatm_usb_probe(intf, id,
                                xusbatm_drivers + (id - xusbatm_usb_ids));
}

static struct usb_driver xusbatm_usb_driver = {
        .name           = xusbatm_driver_name,
        .probe          = xusbatm_usb_probe,
        .disconnect     = usbatm_usb_disconnect,
        .id_table       = xusbatm_usb_ids
};

static int __init xusbatm_init(void)
{
        int i;

        if (!num_vendor ||
            num_vendor != num_product ||
            num_vendor != num_rx_endpoint ||
            num_vendor != num_tx_endpoint) {
                pr_warn("xusbatm: malformed module parameters\n");
                return -EINVAL;
        }

        for (i = 0; i < num_vendor; i++) {
                rx_endpoint[i] |= USB_DIR_IN;
                tx_endpoint[i] &= USB_ENDPOINT_NUMBER_MASK;

                xusbatm_usb_ids[i].match_flags  = USB_DEVICE_ID_MATCH_DEVICE;
                xusbatm_usb_ids[i].idVendor     = vendor[i];
                xusbatm_usb_ids[i].idProduct    = product[i];

                xusbatm_drivers[i].driver_name  = xusbatm_driver_name;
                xusbatm_drivers[i].bind         = xusbatm_bind;
                xusbatm_drivers[i].unbind       = xusbatm_unbind;
                xusbatm_drivers[i].atm_start    = xusbatm_atm_start;
                xusbatm_drivers[i].bulk_in      = rx_endpoint[i];
                xusbatm_drivers[i].bulk_out     = tx_endpoint[i];
                xusbatm_drivers[i].rx_padding   = rx_padding[i];
                xusbatm_drivers[i].tx_padding   = tx_padding[i];
        }

        return usb_register(&xusbatm_usb_driver);
}
module_init(xusbatm_init);

static void __exit xusbatm_exit(void)
{
        usb_deregister(&xusbatm_usb_driver);
}
module_exit(xusbatm_exit);

MODULE_AUTHOR("Roman Kagan, Duncan Sands");
MODULE_DESCRIPTION("Driver for USB ADSL modems initialized in userspace");
MODULE_LICENSE("GPL");