// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Simple "CDC Subset" USB Networking Links
 * Copyright (C) 2000-2005 by David Brownell
 */

#include <linux/module.h>
#include <linux/kmod.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/workqueue.h>
#include <linux/mii.h>
#include <linux/usb.h>
#include <linux/usb/usbnet.h>


/*
 * This supports simple USB network links that don't require any special
 * framing or hardware control operations.  The protocol used here is a
 * strict subset of CDC Ethernet, with three basic differences reflecting
 * the goal that almost any hardware should run it:
 *
 *  - Minimal runtime control:  one interface, no altsettings, and
 *    no vendor or class specific control requests.  If a device is
 *    configured, it is allowed to exchange packets with the host.
 *    Fancier models would mean not working on some hardware.
 *
 *  - Minimal manufacturing control:  no IEEE "Organizationally
 *    Unique ID" required, or an EEPROMs to store one.  Each host uses
 *    one random "locally assigned" Ethernet address instead, which can
 *    of course be overridden using standard tools like "ifconfig".
 *    (With 2^46 such addresses, same-net collisions are quite rare.)
 *
 *  - There is no additional framing data for USB.  Packets are written
 *    exactly as in CDC Ethernet, starting with an Ethernet header and
 *    terminated by a short packet.  However, the host will never send a
 *    zero length packet; some systems can't handle those robustly.
 *
 * Anything that can transmit and receive USB bulk packets can implement
 * this protocol.  That includes both smart peripherals and quite a lot
 * of "host-to-host" USB cables (which embed two devices back-to-back).
 *
 * Note that although Linux may use many of those host-to-host links
 * with this "cdc_subset" framing, that doesn't mean there may not be a
 * better approach.  Handling the "other end unplugs/replugs" scenario
 * well tends to require chip-specific vendor requests.  Also, Windows
 * peers at the other end of host-to-host cables may expect their own
 * framing to be used rather than this "cdc_subset" model.
 */

#if defined(CONFIG_USB_EPSON2888) || defined(CONFIG_USB_ARMLINUX)
/* PDA style devices are always connected if present */
static int always_connected (struct usbnet *dev)
{
        return 0;
}
#endif

#ifdef  CONFIG_USB_ALI_M5632
#define HAVE_HARDWARE

/*-------------------------------------------------------------------------
 *
 * ALi M5632 driver ... does high speed
 *
 * NOTE that the MS-Windows drivers for this chip use some funky and
 * (naturally) undocumented 7-byte prefix to each packet, so this is a
 * case where we don't currently interoperate.  Also, once you unplug
 * one end of the cable, you need to replug the other end too ... since
 * chip docs are unavailable, there's no way to reset the relevant state
 * short of a power cycle.
 *
 *-------------------------------------------------------------------------*/

static void m5632_recover(struct usbnet *dev)
{
        struct usb_device       *udev = dev->udev;
        struct usb_interface    *intf = dev->intf;
        int r;

        r = usb_lock_device_for_reset(udev, intf);
        if (r < 0)
                return;

        usb_reset_device(udev);
        usb_unlock_device(udev);
}

static const struct driver_info ali_m5632_info = {
        .description =  "ALi M5632",
        .flags       = FLAG_POINTTOPOINT,
        .recover     = m5632_recover,
};

#endif

#ifdef  CONFIG_USB_AN2720
#define HAVE_HARDWARE

/*-------------------------------------------------------------------------
 *
 * AnchorChips 2720 driver ... http://www.cypress.com
 *
 * This doesn't seem to have a way to detect whether the peer is
 * connected, or need any reset handshaking.  It's got pretty big
 * internal buffers (handles most of a frame's worth of data).
 * Chip data sheets don't describe any vendor control messages.
 *
 *-------------------------------------------------------------------------*/

static const struct driver_info an2720_info = {
        .description =  "AnchorChips/Cypress 2720",
        .flags       = FLAG_POINTTOPOINT,
        // no reset available!
        // no check_connect available!

        .in = 2, .out = 2,              // direction distinguishes these
};

#endif  /* CONFIG_USB_AN2720 */


#ifdef  CONFIG_USB_BELKIN
#define HAVE_HARDWARE

/*-------------------------------------------------------------------------
 *
 * Belkin F5U104 ... two NetChip 2280 devices + Atmel AVR microcontroller
 *
 * ... also two eTEK designs, including one sold as "Advance USBNET"
 *
 *-------------------------------------------------------------------------*/

static const struct driver_info belkin_info = {
        .description =  "Belkin, eTEK, or compatible",
        .flags       = FLAG_POINTTOPOINT,
};

#endif  /* CONFIG_USB_BELKIN */



#ifdef  CONFIG_USB_EPSON2888
#define HAVE_HARDWARE

/*-------------------------------------------------------------------------
 *
 * EPSON USB clients
 *
 * This is the same idea as Linux PDAs (below) except the firmware in the
 * device might not be Tux-powered.  Epson provides reference firmware that
 * implements this interface.  Product developers can reuse or modify that
 * code, such as by using their own product and vendor codes.
 *
 * Support was from Juro Bystricky <bystricky.juro@erd.epson.com>
 *
 *-------------------------------------------------------------------------*/

static const struct driver_info epson2888_info = {
        .description =  "Epson USB Device",
        .check_connect = always_connected,
        .flags = FLAG_POINTTOPOINT,

        .in = 4, .out = 3,
};

#endif  /* CONFIG_USB_EPSON2888 */


/*-------------------------------------------------------------------------
 *
 * info from Jonathan McDowell <noodles@earth.li>
 *
 *-------------------------------------------------------------------------*/
#ifdef CONFIG_USB_KC2190
#define HAVE_HARDWARE
static const struct driver_info kc2190_info = {
        .description =  "KC Technology KC-190",
        .flags = FLAG_POINTTOPOINT,
};
#endif /* CONFIG_USB_KC2190 */


#ifdef  CONFIG_USB_ARMLINUX
#define HAVE_HARDWARE

/*-------------------------------------------------------------------------
 *
 * Intel's SA-1100 chip integrates basic USB support, and is used
 * in PDAs like some iPaqs, the Yopy, some Zaurus models, and more.
 * When they run Linux, arch/arm/mach-sa1100/usb-eth.c may be used to
 * network using minimal USB framing data.
 *
 * This describes the driver currently in standard ARM Linux kernels.
 * The Zaurus uses a different driver (see later).
 *
 * PXA25x and PXA210 use XScale cores (ARM v5TE) with better USB support
 * and different USB endpoint numbering than the SA1100 devices.  The
 * mach-pxa/usb-eth.c driver re-uses the device ids from mach-sa1100
 * so we rely on the endpoint descriptors.
 *
 *-------------------------------------------------------------------------*/

static const struct driver_info linuxdev_info = {
        .description =  "Linux Device",
        .check_connect = always_connected,
        .flags = FLAG_POINTTOPOINT,
};

static const struct driver_info yopy_info = {
        .description =  "Yopy",
        .check_connect = always_connected,
        .flags = FLAG_POINTTOPOINT,
};

static const struct driver_info blob_info = {
        .description =  "Boot Loader OBject",
        .check_connect = always_connected,
        .flags = FLAG_POINTTOPOINT,
};

#endif  /* CONFIG_USB_ARMLINUX */


/*-------------------------------------------------------------------------*/

#ifndef HAVE_HARDWARE
#warning You need to configure some hardware for this driver
#endif

/*
 * chip vendor names won't normally be on the cables, and
 * may not be on the device.
 */

static const struct usb_device_id       products [] = {

#ifdef  CONFIG_USB_ALI_M5632
{
        USB_DEVICE (0x0402, 0x5632),    // ALi defaults
        .driver_info =  (unsigned long) &ali_m5632_info,
},
{
        USB_DEVICE (0x182d,0x207c),     // SiteCom CN-124
        .driver_info =  (unsigned long) &ali_m5632_info,
},
#endif

#ifdef  CONFIG_USB_AN2720
{
        USB_DEVICE (0x0547, 0x2720),    // AnchorChips defaults
        .driver_info =  (unsigned long) &an2720_info,
}, {
        USB_DEVICE (0x0547, 0x2727),    // Xircom PGUNET
        .driver_info =  (unsigned long) &an2720_info,
},
#endif

#ifdef  CONFIG_USB_BELKIN
{
        USB_DEVICE (0x050d, 0x0004),    // Belkin
        .driver_info =  (unsigned long) &belkin_info,
}, {
        USB_DEVICE (0x056c, 0x8100),    // eTEK
        .driver_info =  (unsigned long) &belkin_info,
}, {
        USB_DEVICE (0x0525, 0x9901),    // Advance USBNET (eTEK)
        .driver_info =  (unsigned long) &belkin_info,
},
#endif

#ifdef  CONFIG_USB_EPSON2888
{
        USB_DEVICE (0x0525, 0x2888),    // EPSON USB client
        .driver_info    = (unsigned long) &epson2888_info,
},
#endif

#ifdef CONFIG_USB_KC2190
{
        USB_DEVICE (0x050f, 0x0190),    // KC-190
        .driver_info =  (unsigned long) &kc2190_info,
},
#endif

#ifdef  CONFIG_USB_ARMLINUX
/*
 * SA-1100 using standard ARM Linux kernels, or compatible.
 * Often used when talking to Linux PDAs (iPaq, Yopy, etc).
 * The sa-1100 "usb-eth" driver handles the basic framing.
 *
 * PXA25x or PXA210 ...  these use a "usb-eth" driver much like
 * the sa1100 one, but hardware uses different endpoint numbers.
 *
 * Or the Linux "Ethernet" gadget on hardware that can't talk
 * CDC Ethernet (e.g., no altsettings), in either of two modes:
 *  - acting just like the old "usb-eth" firmware, though
 *    the implementation is different
 *  - supporting RNDIS as the first/default configuration for
 *    MS-Windows interop; Linux needs to use the other config
 */
{
        // 1183 = 0x049F, both used as hex values?
        // Compaq "Itsy" vendor/product id
        USB_DEVICE (0x049F, 0x505A),    // usb-eth, or compatible
        .driver_info =  (unsigned long) &linuxdev_info,
}, {
        USB_DEVICE (0x0E7E, 0x1001),    // G.Mate "Yopy"
        .driver_info =  (unsigned long) &yopy_info,
}, {
        USB_DEVICE (0x8086, 0x07d3),    // "blob" bootloader
        .driver_info =  (unsigned long) &blob_info,
}, {
        USB_DEVICE (0x1286, 0x8001),    // "blob" bootloader
        .driver_info =  (unsigned long) &blob_info,
}, {
        // Linux Ethernet/RNDIS gadget, mostly on PXA, second config
        // e.g. Gumstix, current OpenZaurus, ... or anything else
        // that just enables this gadget option.
        USB_DEVICE (0x0525, 0xa4a2),
        .driver_info =  (unsigned long) &linuxdev_info,
},
#endif

        { },            // END
};
MODULE_DEVICE_TABLE(usb, products);

/*-------------------------------------------------------------------------*/
static int dummy_prereset(struct usb_interface *intf)
{
        return 0;
}

static int dummy_postreset(struct usb_interface *intf)
{
        return 0;
}

static struct usb_driver cdc_subset_driver = {
        .name =         "cdc_subset",
        .probe =        usbnet_probe,
        .suspend =      usbnet_suspend,
        .resume =       usbnet_resume,
        .pre_reset =    dummy_prereset,
        .post_reset =   dummy_postreset,
        .disconnect =   usbnet_disconnect,
        .id_table =     products,
        .disable_hub_initiated_lpm = 1,
};

module_usb_driver(cdc_subset_driver);

MODULE_AUTHOR("David Brownell");
MODULE_DESCRIPTION("Simple 'CDC Subset' USB networking links");
MODULE_LICENSE("GPL");