// SPDX-License-Identifier: GPL-2.0-only
/*
 * phonet.c -- USB CDC Phonet host driver
 *
 * Copyright (C) 2008-2009 Nokia Corporation. All rights reserved.
 *
 * Author: Rémi Denis-Courmont
 */

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/gfp.h>
#include <linux/usb.h>
#include <linux/usb/cdc.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/if_phonet.h>
#include <linux/phonet.h>

#define PN_MEDIA_USB    0x1B

static const unsigned rxq_size = 17;

struct usbpn_dev {
        struct net_device       *dev;

        struct usb_interface    *intf, *data_intf;
        struct usb_device       *usb;
        unsigned int            tx_pipe, rx_pipe;
        u8 active_setting;
        u8 disconnected;

        unsigned                tx_queue;
        spinlock_t              tx_lock;

        spinlock_t              rx_lock;
        struct sk_buff          *rx_skb;
        struct urb              *urbs[];
};

static void tx_complete(struct urb *req);
static void rx_complete(struct urb *req);

/*
 * Network device callbacks
 */
static netdev_tx_t usbpn_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct usbpn_dev *pnd = netdev_priv(dev);
        struct urb *req = NULL;
        unsigned long flags;
        int err;

        if (skb->protocol != htons(ETH_P_PHONET))
                goto drop;

        req = usb_alloc_urb(0, GFP_ATOMIC);
        if (!req)
                goto drop;
        usb_fill_bulk_urb(req, pnd->usb, pnd->tx_pipe, skb->data, skb->len,
                                tx_complete, skb);
        req->transfer_flags = URB_ZERO_PACKET;
        err = usb_submit_urb(req, GFP_ATOMIC);
        if (err) {
                usb_free_urb(req);
                goto drop;
        }

        spin_lock_irqsave(&pnd->tx_lock, flags);
        pnd->tx_queue++;
        if (pnd->tx_queue >= dev->tx_queue_len)
                netif_stop_queue(dev);
        spin_unlock_irqrestore(&pnd->tx_lock, flags);
        return NETDEV_TX_OK;

drop:
        dev_kfree_skb(skb);
        dev->stats.tx_dropped++;
        return NETDEV_TX_OK;
}

static void tx_complete(struct urb *req)
{
        struct sk_buff *skb = req->context;
        struct net_device *dev = skb->dev;
        struct usbpn_dev *pnd = netdev_priv(dev);
        int status = req->status;
        unsigned long flags;

        switch (status) {
        case 0:
                dev->stats.tx_bytes += skb->len;
                break;

        case -ENOENT:
        case -ECONNRESET:
        case -ESHUTDOWN:
                dev->stats.tx_aborted_errors++;
                fallthrough;
        default:
                dev->stats.tx_errors++;
                dev_dbg(&dev->dev, "TX error (%d)\n", status);
        }
        dev->stats.tx_packets++;

        spin_lock_irqsave(&pnd->tx_lock, flags);
        pnd->tx_queue--;
        netif_wake_queue(dev);
        spin_unlock_irqrestore(&pnd->tx_lock, flags);

        dev_kfree_skb_any(skb);
        usb_free_urb(req);
}

static int rx_submit(struct usbpn_dev *pnd, struct urb *req, gfp_t gfp_flags)
{
        struct net_device *dev = pnd->dev;
        struct page *page;
        int err;

        page = __dev_alloc_page(gfp_flags | __GFP_NOMEMALLOC);
        if (!page)
                return -ENOMEM;

        usb_fill_bulk_urb(req, pnd->usb, pnd->rx_pipe, page_address(page),
                                PAGE_SIZE, rx_complete, dev);
        req->transfer_flags = 0;
        err = usb_submit_urb(req, gfp_flags);
        if (unlikely(err)) {
                dev_dbg(&dev->dev, "RX submit error (%d)\n", err);
                put_page(page);
        }
        return err;
}

static void rx_complete(struct urb *req)
{
        struct net_device *dev = req->context;
        struct usbpn_dev *pnd = netdev_priv(dev);
        struct page *page = virt_to_page(req->transfer_buffer);
        struct sk_buff *skb;
        unsigned long flags;
        int status = req->status;

        switch (status) {
        case 0:
                spin_lock_irqsave(&pnd->rx_lock, flags);
                skb = pnd->rx_skb;
                if (!skb) {
                        skb = pnd->rx_skb = netdev_alloc_skb(dev, 12);
                        if (likely(skb)) {
                                /* Can't use pskb_pull() on page in IRQ */
                                skb_put_data(skb, page_address(page), 1);
                                skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
                                                page, 1, req->actual_length,
                                                PAGE_SIZE);
                                page = NULL;
                        }
                } else {
                        skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
                                        page, 0, req->actual_length,
                                        PAGE_SIZE);
                        page = NULL;
                }
                if (req->actual_length < PAGE_SIZE)
                        pnd->rx_skb = NULL; /* Last fragment */
                else
                        skb = NULL;
                spin_unlock_irqrestore(&pnd->rx_lock, flags);
                if (skb) {
                        skb->protocol = htons(ETH_P_PHONET);
                        skb_reset_mac_header(skb);
                        __skb_pull(skb, 1);
                        skb->dev = dev;
                        dev->stats.rx_packets++;
                        dev->stats.rx_bytes += skb->len;

                        netif_rx(skb);
                }
                goto resubmit;

        case -ENOENT:
        case -ECONNRESET:
        case -ESHUTDOWN:
                req = NULL;
                break;

        case -EOVERFLOW:
                dev->stats.rx_over_errors++;
                dev_dbg(&dev->dev, "RX overflow\n");
                break;

        case -EILSEQ:
                dev->stats.rx_crc_errors++;
                break;
        }

        dev->stats.rx_errors++;
resubmit:
        if (page)
                put_page(page);
        if (req)
                rx_submit(pnd, req, GFP_ATOMIC);
}

static int usbpn_close(struct net_device *dev);

static int usbpn_open(struct net_device *dev)
{
        struct usbpn_dev *pnd = netdev_priv(dev);
        int err;
        unsigned i;
        unsigned num = pnd->data_intf->cur_altsetting->desc.bInterfaceNumber;

        err = usb_set_interface(pnd->usb, num, pnd->active_setting);
        if (err)
                return err;

        for (i = 0; i < rxq_size; i++) {
                struct urb *req = usb_alloc_urb(0, GFP_KERNEL);

                if (!req || rx_submit(pnd, req, GFP_KERNEL)) {
                        usb_free_urb(req);
                        usbpn_close(dev);
                        return -ENOMEM;
                }
                pnd->urbs[i] = req;
        }

        netif_wake_queue(dev);
        return 0;
}

static int usbpn_close(struct net_device *dev)
{
        struct usbpn_dev *pnd = netdev_priv(dev);
        unsigned i;
        unsigned num = pnd->data_intf->cur_altsetting->desc.bInterfaceNumber;

        netif_stop_queue(dev);

        for (i = 0; i < rxq_size; i++) {
                struct urb *req = pnd->urbs[i];

                if (!req)
                        continue;
                usb_kill_urb(req);
                usb_free_urb(req);
                pnd->urbs[i] = NULL;
        }

        return usb_set_interface(pnd->usb, num, !pnd->active_setting);
}

static int usbpn_siocdevprivate(struct net_device *dev, struct ifreq *ifr,
                                void __user *data, int cmd)
{
        struct if_phonet_req *req = (struct if_phonet_req *)ifr;

        switch (cmd) {
        case SIOCPNGAUTOCONF:
                req->ifr_phonet_autoconf.device = PN_DEV_PC;
                return 0;
        }
        return -ENOIOCTLCMD;
}

static const struct net_device_ops usbpn_ops = {
        .ndo_open       = usbpn_open,
        .ndo_stop       = usbpn_close,
        .ndo_start_xmit = usbpn_xmit,
        .ndo_siocdevprivate = usbpn_siocdevprivate,
};

static void usbpn_setup(struct net_device *dev)
{
        const u8 addr = PN_MEDIA_USB;

        dev->features           = 0;
        dev->netdev_ops         = &usbpn_ops;
        dev->header_ops         = &phonet_header_ops;
        dev->type               = ARPHRD_PHONET;
        dev->flags              = IFF_POINTOPOINT | IFF_NOARP;
        dev->mtu                = PHONET_MAX_MTU;
        dev->min_mtu            = PHONET_MIN_MTU;
        dev->max_mtu            = PHONET_MAX_MTU;
        dev->hard_header_len    = 1;
        dev->addr_len           = 1;
        dev_addr_set(dev, &addr);
        dev->tx_queue_len       = 3;

        dev->needs_free_netdev  = true;
}

/*
 * USB driver callbacks
 */
static const struct usb_device_id usbpn_ids[] = {
        {
                .match_flags = USB_DEVICE_ID_MATCH_VENDOR
                        | USB_DEVICE_ID_MATCH_INT_CLASS
                        | USB_DEVICE_ID_MATCH_INT_SUBCLASS,
                .idVendor = 0x0421, /* Nokia */
                .bInterfaceClass = USB_CLASS_COMM,
                .bInterfaceSubClass = 0xFE,
        },
        { },
};

MODULE_DEVICE_TABLE(usb, usbpn_ids);

static struct usb_driver usbpn_driver;

static int usbpn_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
        static const char ifname[] = "usbpn%d";
        const struct usb_cdc_union_desc *union_header = NULL;
        const struct usb_host_interface *data_desc;
        struct usb_interface *data_intf;
        struct usb_device *usbdev = interface_to_usbdev(intf);
        struct net_device *dev;
        struct usbpn_dev *pnd;
        u8 *data;
        int phonet = 0;
        int len, err;
        struct usb_cdc_parsed_header hdr;

        data = intf->altsetting->extra;
        len = intf->altsetting->extralen;
        cdc_parse_cdc_header(&hdr, intf, data, len);
        union_header = hdr.usb_cdc_union_desc;
        phonet = hdr.phonet_magic_present;

        if (!union_header || !phonet)
                return -EINVAL;

        data_intf = usb_ifnum_to_if(usbdev, union_header->bSlaveInterface0);
        if (data_intf == NULL)
                return -ENODEV;
        /* Data interface has one inactive and one active setting */
        if (data_intf->num_altsetting != 2)
                return -EINVAL;
        if (data_intf->altsetting[0].desc.bNumEndpoints == 0 &&
            data_intf->altsetting[1].desc.bNumEndpoints == 2)
                data_desc = data_intf->altsetting + 1;
        else
        if (data_intf->altsetting[0].desc.bNumEndpoints == 2 &&
            data_intf->altsetting[1].desc.bNumEndpoints == 0)
                data_desc = data_intf->altsetting;
        else
                return -EINVAL;

        dev = alloc_netdev(struct_size(pnd, urbs, rxq_size), ifname,
                           NET_NAME_UNKNOWN, usbpn_setup);
        if (!dev)
                return -ENOMEM;

        pnd = netdev_priv(dev);
        SET_NETDEV_DEV(dev, &intf->dev);

        pnd->dev = dev;
        pnd->usb = usbdev;
        pnd->intf = intf;
        pnd->data_intf = data_intf;
        spin_lock_init(&pnd->tx_lock);
        spin_lock_init(&pnd->rx_lock);
        /* Endpoints */
        if (usb_pipein(data_desc->endpoint[0].desc.bEndpointAddress)) {
                pnd->rx_pipe = usb_rcvbulkpipe(usbdev,
                        data_desc->endpoint[0].desc.bEndpointAddress);
                pnd->tx_pipe = usb_sndbulkpipe(usbdev,
                        data_desc->endpoint[1].desc.bEndpointAddress);
        } else {
                pnd->rx_pipe = usb_rcvbulkpipe(usbdev,
                        data_desc->endpoint[1].desc.bEndpointAddress);
                pnd->tx_pipe = usb_sndbulkpipe(usbdev,
                        data_desc->endpoint[0].desc.bEndpointAddress);
        }
        pnd->active_setting = data_desc - data_intf->altsetting;

        err = usb_driver_claim_interface(&usbpn_driver, data_intf, pnd);
        if (err)
                goto out;

        /* Force inactive mode until the network device is brought UP */
        usb_set_interface(usbdev, union_header->bSlaveInterface0,
                                !pnd->active_setting);
        usb_set_intfdata(intf, pnd);

        err = register_netdev(dev);
        if (err) {
                /* Set disconnected flag so that disconnect() returns early. */
                pnd->disconnected = 1;
                usb_driver_release_interface(&usbpn_driver, data_intf);
                goto out;
        }

        dev_dbg(&dev->dev, "USB CDC Phonet device found\n");
        return 0;

out:
        usb_set_intfdata(intf, NULL);
        free_netdev(dev);
        return err;
}

static void usbpn_disconnect(struct usb_interface *intf)
{
        struct usbpn_dev *pnd = usb_get_intfdata(intf);

        if (pnd->disconnected)
                return;

        pnd->disconnected = 1;
        usb_driver_release_interface(&usbpn_driver,
                        (pnd->intf == intf) ? pnd->data_intf : pnd->intf);
        unregister_netdev(pnd->dev);
}

static struct usb_driver usbpn_driver = {
        .name =         "cdc_phonet",
        .probe =        usbpn_probe,
        .disconnect =   usbpn_disconnect,
        .id_table =     usbpn_ids,
        .disable_hub_initiated_lpm = 1,
};

module_usb_driver(usbpn_driver);

MODULE_AUTHOR("Remi Denis-Courmont");
MODULE_DESCRIPTION("USB CDC Phonet host interface");
MODULE_LICENSE("GPL");