/*
 * Host Side support for RNDIS Networking Links
 * Copyright (C) 2005 by David Brownell
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include <linux/module.h>
#include <linux/init.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/cdc.h>
#include <linux/usb/usbnet.h>
#include <linux/usb/rndis_host.h>


/*
 * RNDIS is NDIS remoted over USB.  It's a MSFT variant of CDC ACM ... of
 * course ACM was intended for modems, not Ethernet links!  USB's standard
 * for Ethernet links is "CDC Ethernet", which is significantly simpler.
 *
 * NOTE that Microsoft's "RNDIS 1.0" specification is incomplete.  Issues
 * include:
 *    - Power management in particular relies on information that's scattered
 *      through other documentation, and which is incomplete or incorrect even
 *      there.
 *    - There are various undocumented protocol requirements, such as the
 *      need to send unused garbage in control-OUT messages.
 *    - In some cases, MS-Windows will emit undocumented requests; this
 *      matters more to peripheral implementations than host ones.
 *
 * Moreover there's a no-open-specs variant of RNDIS called "ActiveSync".
 *
 * For these reasons and others, ** USE OF RNDIS IS STRONGLY DISCOURAGED ** in
 * favor of such non-proprietary alternatives as CDC Ethernet or the newer (and
 * currently rare) "Ethernet Emulation Model" (EEM).
 */

/*
 * RNDIS notifications from device: command completion; "reverse"
 * keepalives; etc
 */
void rndis_status(struct usbnet *dev, struct urb *urb)
{
        devdbg(dev, "rndis status urb, len %d stat %d",
                urb->actual_length, urb->status);
        // FIXME for keepalives, respond immediately (asynchronously)
        // if not an RNDIS status, do like cdc_status(dev,urb) does
}
EXPORT_SYMBOL_GPL(rndis_status);

/*
 * RNDIS indicate messages.
 */
static void rndis_msg_indicate(struct usbnet *dev, struct rndis_indicate *msg,
                                int buflen)
{
        struct cdc_state *info = (void *)&dev->data;
        struct device *udev = &info->control->dev;

        if (dev->driver_info->indication) {
                dev->driver_info->indication(dev, msg, buflen);
        } else {
                switch (msg->status) {
                case RNDIS_STATUS_MEDIA_CONNECT:
                        dev_info(udev, "rndis media connect\n");
                        break;
                case RNDIS_STATUS_MEDIA_DISCONNECT:
                        dev_info(udev, "rndis media disconnect\n");
                        break;
                default:
                        dev_info(udev, "rndis indication: 0x%08x\n",
                                        le32_to_cpu(msg->status));
                }
        }
}

/*
 * RPC done RNDIS-style.  Caller guarantees:
 * - message is properly byteswapped
 * - there's no other request pending
 * - buf can hold up to 1KB response (required by RNDIS spec)
 * On return, the first few entries are already byteswapped.
 *
 * Call context is likely probe(), before interface name is known,
 * which is why we won't try to use it in the diagnostics.
 */
int rndis_command(struct usbnet *dev, struct rndis_msg_hdr *buf, int buflen)
{
        struct cdc_state        *info = (void *) &dev->data;
        int                     master_ifnum;
        int                     retval;
        unsigned                count;
        __le32                  rsp;
        u32                     xid = 0, msg_len, request_id;

        /* REVISIT when this gets called from contexts other than probe() or
         * disconnect(): either serialize, or dispatch responses on xid
         */

        /* Issue the request; xid is unique, don't bother byteswapping it */
        if (likely(buf->msg_type != RNDIS_MSG_HALT
                        && buf->msg_type != RNDIS_MSG_RESET)) {
                xid = dev->xid++;
                if (!xid)
                        xid = dev->xid++;
                buf->request_id = (__force __le32) xid;
        }
        master_ifnum = info->control->cur_altsetting->desc.bInterfaceNumber;
        retval = usb_control_msg(dev->udev,
                usb_sndctrlpipe(dev->udev, 0),
                USB_CDC_SEND_ENCAPSULATED_COMMAND,
                USB_TYPE_CLASS | USB_RECIP_INTERFACE,
                0, master_ifnum,
                buf, le32_to_cpu(buf->msg_len),
                RNDIS_CONTROL_TIMEOUT_MS);
        if (unlikely(retval < 0 || xid == 0))
                return retval;

        // FIXME Seems like some devices discard responses when
        // we time out and cancel our "get response" requests...
        // so, this is fragile.  Probably need to poll for status.

        /* ignore status endpoint, just poll the control channel;
         * the request probably completed immediately
         */
        rsp = buf->msg_type | RNDIS_MSG_COMPLETION;
        for (count = 0; count < 10; count++) {
                memset(buf, 0, CONTROL_BUFFER_SIZE);
                retval = usb_control_msg(dev->udev,
                        usb_rcvctrlpipe(dev->udev, 0),
                        USB_CDC_GET_ENCAPSULATED_RESPONSE,
                        USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
                        0, master_ifnum,
                        buf, buflen,
                        RNDIS_CONTROL_TIMEOUT_MS);
                if (likely(retval >= 8)) {
                        msg_len = le32_to_cpu(buf->msg_len);
                        request_id = (__force u32) buf->request_id;
                        if (likely(buf->msg_type == rsp)) {
                                if (likely(request_id == xid)) {
                                        if (unlikely(rsp == RNDIS_MSG_RESET_C))
                                                return 0;
                                        if (likely(RNDIS_STATUS_SUCCESS
                                                        == buf->status))
                                                return 0;
                                        dev_dbg(&info->control->dev,
                                                "rndis reply status %08x\n",
                                                le32_to_cpu(buf->status));
                                        return -EL3RST;
                                }
                                dev_dbg(&info->control->dev,
                                        "rndis reply id %d expected %d\n",
                                        request_id, xid);
                                /* then likely retry */
                        } else switch (buf->msg_type) {
                        case RNDIS_MSG_INDICATE:        /* fault/event */
                                rndis_msg_indicate(dev, (void *)buf, buflen);

                                break;
                        case RNDIS_MSG_KEEPALIVE: {     /* ping */
                                struct rndis_keepalive_c *msg = (void *)buf;

                                msg->msg_type = RNDIS_MSG_KEEPALIVE_C;
                                msg->msg_len = cpu_to_le32(sizeof *msg);
                                msg->status = RNDIS_STATUS_SUCCESS;
                                retval = usb_control_msg(dev->udev,
                                        usb_sndctrlpipe(dev->udev, 0),
                                        USB_CDC_SEND_ENCAPSULATED_COMMAND,
                                        USB_TYPE_CLASS | USB_RECIP_INTERFACE,
                                        0, master_ifnum,
                                        msg, sizeof *msg,
                                        RNDIS_CONTROL_TIMEOUT_MS);
                                if (unlikely(retval < 0))
                                        dev_dbg(&info->control->dev,
                                                "rndis keepalive err %d\n",
                                                retval);
                                }
                                break;
                        default:
                                dev_dbg(&info->control->dev,
                                        "unexpected rndis msg %08x len %d\n",
                                        le32_to_cpu(buf->msg_type), msg_len);
                        }
                } else {
                        /* device probably issued a protocol stall; ignore */
                        dev_dbg(&info->control->dev,
                                "rndis response error, code %d\n", retval);
                }
                msleep(20);
        }
        dev_dbg(&info->control->dev, "rndis response timeout\n");
        return -ETIMEDOUT;
}
EXPORT_SYMBOL_GPL(rndis_command);

/*
 * rndis_query:
 *
 * Performs a query for @oid along with 0 or more bytes of payload as
 * specified by @in_len. If @reply_len is not set to -1 then the reply
 * length is checked against this value, resulting in an error if it
 * doesn't match.
 *
 * NOTE: Adding a payload exactly or greater than the size of the expected
 * response payload is an evident requirement MSFT added for ActiveSync.
 *
 * The only exception is for OIDs that return a variably sized response,
 * in which case no payload should be added.  This undocumented (and
 * nonsensical!) issue was found by sniffing protocol requests from the
 * ActiveSync 4.1 Windows driver.
 */
static int rndis_query(struct usbnet *dev, struct usb_interface *intf,
                void *buf, __le32 oid, u32 in_len,
                void **reply, int *reply_len)
{
        int retval;
        union {
                void                    *buf;
                struct rndis_msg_hdr    *header;
                struct rndis_query      *get;
                struct rndis_query_c    *get_c;
        } u;
        u32 off, len;

        u.buf = buf;

        memset(u.get, 0, sizeof *u.get + in_len);
        u.get->msg_type = RNDIS_MSG_QUERY;
        u.get->msg_len = cpu_to_le32(sizeof *u.get + in_len);
        u.get->oid = oid;
        u.get->len = cpu_to_le32(in_len);
        u.get->offset = cpu_to_le32(20);

        retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
        if (unlikely(retval < 0)) {
                dev_err(&intf->dev, "RNDIS_MSG_QUERY(0x%08x) failed, %d\n",
                                oid, retval);
                return retval;
        }

        off = le32_to_cpu(u.get_c->offset);
        len = le32_to_cpu(u.get_c->len);
        if (unlikely((8 + off + len) > CONTROL_BUFFER_SIZE))
                goto response_error;

        if (*reply_len != -1 && len != *reply_len)
                goto response_error;

        *reply = (unsigned char *) &u.get_c->request_id + off;
        *reply_len = len;

        return retval;

response_error:
        dev_err(&intf->dev, "RNDIS_MSG_QUERY(0x%08x) "
                        "invalid response - off %d len %d\n",
                oid, off, len);
        return -EDOM;
}

/* same as usbnet_netdev_ops but MTU change not allowed */
static const struct net_device_ops rndis_netdev_ops = {
        .ndo_open               = usbnet_open,
        .ndo_stop               = usbnet_stop,
        .ndo_start_xmit         = usbnet_start_xmit,
        .ndo_tx_timeout         = usbnet_tx_timeout,
        .ndo_set_mac_address    = eth_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
};

int
generic_rndis_bind(struct usbnet *dev, struct usb_interface *intf, int flags)
{
        int                     retval;
        struct net_device       *net = dev->net;
        struct cdc_state        *info = (void *) &dev->data;
        union {
                void                    *buf;
                struct rndis_msg_hdr    *header;
                struct rndis_init       *init;
                struct rndis_init_c     *init_c;
                struct rndis_query      *get;
                struct rndis_query_c    *get_c;
                struct rndis_set        *set;
                struct rndis_set_c      *set_c;
                struct rndis_halt       *halt;
        } u;
        u32                     tmp;
        __le32                  phym_unspec, *phym;
        int                     reply_len;
        unsigned char           *bp;

        /* we can't rely on i/o from stack working, or stack allocation */
        u.buf = kmalloc(CONTROL_BUFFER_SIZE, GFP_KERNEL);
        if (!u.buf)
                return -ENOMEM;
        retval = usbnet_generic_cdc_bind(dev, intf);
        if (retval < 0)
                goto fail;

        u.init->msg_type = RNDIS_MSG_INIT;
        u.init->msg_len = cpu_to_le32(sizeof *u.init);
        u.init->major_version = cpu_to_le32(1);
        u.init->minor_version = cpu_to_le32(0);

        /* max transfer (in spec) is 0x4000 at full speed, but for
         * TX we'll stick to one Ethernet packet plus RNDIS framing.
         * For RX we handle drivers that zero-pad to end-of-packet.
         * Don't let userspace change these settings.
         *
         * NOTE: there still seems to be wierdness here, as if we need
         * to do some more things to make sure WinCE targets accept this.
         * They default to jumbograms of 8KB or 16KB, which is absurd
         * for such low data rates and which is also more than Linux
         * can usually expect to allocate for SKB data...
         */
        net->hard_header_len += sizeof (struct rndis_data_hdr);
        dev->hard_mtu = net->mtu + net->hard_header_len;

        dev->maxpacket = usb_maxpacket(dev->udev, dev->out, 1);
        if (dev->maxpacket == 0) {
                if (netif_msg_probe(dev))
                        dev_dbg(&intf->dev, "dev->maxpacket can't be 0\n");
                retval = -EINVAL;
                goto fail_and_release;
        }

        dev->rx_urb_size = dev->hard_mtu + (dev->maxpacket + 1);
        dev->rx_urb_size &= ~(dev->maxpacket - 1);
        u.init->max_transfer_size = cpu_to_le32(dev->rx_urb_size);

        net->netdev_ops = &rndis_netdev_ops;

        retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
        if (unlikely(retval < 0)) {
                /* it might not even be an RNDIS device!! */
                dev_err(&intf->dev, "RNDIS init failed, %d\n", retval);
                goto fail_and_release;
        }
        tmp = le32_to_cpu(u.init_c->max_transfer_size);
        if (tmp < dev->hard_mtu) {
                if (tmp <= net->hard_header_len) {
                        dev_err(&intf->dev,
                                "dev can't take %u byte packets (max %u)\n",
                                dev->hard_mtu, tmp);
                        retval = -EINVAL;
                        goto halt_fail_and_release;
                }
                dev_warn(&intf->dev,
                         "dev can't take %u byte packets (max %u), "
                         "adjusting MTU to %u\n",
                         dev->hard_mtu, tmp, tmp - net->hard_header_len);
                dev->hard_mtu = tmp;
                net->mtu = dev->hard_mtu - net->hard_header_len;
        }

        /* REVISIT:  peripheral "alignment" request is ignored ... */
        dev_dbg(&intf->dev,
                "hard mtu %u (%u from dev), rx buflen %Zu, align %d\n",
                dev->hard_mtu, tmp, dev->rx_urb_size,
                1 << le32_to_cpu(u.init_c->packet_alignment));

        /* module has some device initialization code needs to be done right
         * after RNDIS_INIT */
        if (dev->driver_info->early_init &&
                        dev->driver_info->early_init(dev) != 0)
                goto halt_fail_and_release;

        /* Check physical medium */
        phym = NULL;
        reply_len = sizeof *phym;
        retval = rndis_query(dev, intf, u.buf, OID_GEN_PHYSICAL_MEDIUM,
                        0, (void **) &phym, &reply_len);
        if (retval != 0 || !phym) {
                /* OID is optional so don't fail here. */
                phym_unspec = RNDIS_PHYSICAL_MEDIUM_UNSPECIFIED;
                phym = &phym_unspec;
        }
        if ((flags & FLAG_RNDIS_PHYM_WIRELESS) &&
                        *phym != RNDIS_PHYSICAL_MEDIUM_WIRELESS_LAN) {
                if (netif_msg_probe(dev))
                        dev_dbg(&intf->dev, "driver requires wireless "
                                "physical medium, but device is not.\n");
                retval = -ENODEV;
                goto halt_fail_and_release;
        }
        if ((flags & FLAG_RNDIS_PHYM_NOT_WIRELESS) &&
                        *phym == RNDIS_PHYSICAL_MEDIUM_WIRELESS_LAN) {
                if (netif_msg_probe(dev))
                        dev_dbg(&intf->dev, "driver requires non-wireless "
                                "physical medium, but device is wireless.\n");
                retval = -ENODEV;
                goto halt_fail_and_release;
        }

        /* Get designated host ethernet address */
        reply_len = ETH_ALEN;
        retval = rndis_query(dev, intf, u.buf, OID_802_3_PERMANENT_ADDRESS,
                        48, (void **) &bp, &reply_len);
        if (unlikely(retval< 0)) {
                dev_err(&intf->dev, "rndis get ethaddr, %d\n", retval);
                goto halt_fail_and_release;
        }
        memcpy(net->dev_addr, bp, ETH_ALEN);
        memcpy(net->perm_addr, bp, ETH_ALEN);

        /* set a nonzero filter to enable data transfers */
        memset(u.set, 0, sizeof *u.set);
        u.set->msg_type = RNDIS_MSG_SET;
        u.set->msg_len = cpu_to_le32(4 + sizeof *u.set);
        u.set->oid = OID_GEN_CURRENT_PACKET_FILTER;
        u.set->len = cpu_to_le32(4);
        u.set->offset = cpu_to_le32((sizeof *u.set) - 8);
        *(__le32 *)(u.buf + sizeof *u.set) = RNDIS_DEFAULT_FILTER;

        retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
        if (unlikely(retval < 0)) {
                dev_err(&intf->dev, "rndis set packet filter, %d\n", retval);
                goto halt_fail_and_release;
        }

        retval = 0;

        kfree(u.buf);
        return retval;

halt_fail_and_release:
        memset(u.halt, 0, sizeof *u.halt);
        u.halt->msg_type = RNDIS_MSG_HALT;
        u.halt->msg_len = cpu_to_le32(sizeof *u.halt);
        (void) rndis_command(dev, (void *)u.halt, CONTROL_BUFFER_SIZE);
fail_and_release:
        usb_set_intfdata(info->data, NULL);
        usb_driver_release_interface(driver_of(intf), info->data);
        info->data = NULL;
fail:
        kfree(u.buf);
        return retval;
}
EXPORT_SYMBOL_GPL(generic_rndis_bind);

static int rndis_bind(struct usbnet *dev, struct usb_interface *intf)
{
        return generic_rndis_bind(dev, intf, FLAG_RNDIS_PHYM_NOT_WIRELESS);
}

void rndis_unbind(struct usbnet *dev, struct usb_interface *intf)
{
        struct rndis_halt       *halt;

        /* try to clear any rndis state/activity (no i/o from stack!) */
        halt = kzalloc(CONTROL_BUFFER_SIZE, GFP_KERNEL);
        if (halt) {
                halt->msg_type = RNDIS_MSG_HALT;
                halt->msg_len = cpu_to_le32(sizeof *halt);
                (void) rndis_command(dev, (void *)halt, CONTROL_BUFFER_SIZE);
                kfree(halt);
        }

        usbnet_cdc_unbind(dev, intf);
}
EXPORT_SYMBOL_GPL(rndis_unbind);

/*
 * DATA -- host must not write zlps
 */
int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
        /* peripheral may have batched packets to us... */
        while (likely(skb->len)) {
                struct rndis_data_hdr   *hdr = (void *)skb->data;
                struct sk_buff          *skb2;
                u32                     msg_len, data_offset, data_len;

                msg_len = le32_to_cpu(hdr->msg_len);
                data_offset = le32_to_cpu(hdr->data_offset);
                data_len = le32_to_cpu(hdr->data_len);

                /* don't choke if we see oob, per-packet data, etc */
                if (unlikely(hdr->msg_type != RNDIS_MSG_PACKET
                                || skb->len < msg_len
                                || (data_offset + data_len + 8) > msg_len)) {
                        dev->net->stats.rx_frame_errors++;
                        devdbg(dev, "bad rndis message %d/%d/%d/%d, len %d",
                                le32_to_cpu(hdr->msg_type),
                                msg_len, data_offset, data_len, skb->len);
                        return 0;
                }
                skb_pull(skb, 8 + data_offset);

                /* at most one packet left? */
                if (likely((data_len - skb->len) <= sizeof *hdr)) {
                        skb_trim(skb, data_len);
                        break;
                }

                /* try to return all the packets in the batch */
                skb2 = skb_clone(skb, GFP_ATOMIC);
                if (unlikely(!skb2))
                        break;
                skb_pull(skb, msg_len - sizeof *hdr);
                skb_trim(skb2, data_len);
                usbnet_skb_return(dev, skb2);
        }

        /* caller will usbnet_skb_return the remaining packet */
        return 1;
}
EXPORT_SYMBOL_GPL(rndis_rx_fixup);

struct sk_buff *
rndis_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
{
        struct rndis_data_hdr   *hdr;
        struct sk_buff          *skb2;
        unsigned                len = skb->len;

        if (likely(!skb_cloned(skb))) {
                int     room = skb_headroom(skb);

                /* enough head room as-is? */
                if (unlikely((sizeof *hdr) <= room))
                        goto fill;

                /* enough room, but needs to be readjusted? */
                room += skb_tailroom(skb);
                if (likely((sizeof *hdr) <= room)) {
                        skb->data = memmove(skb->head + sizeof *hdr,
                                            skb->data, len);
                        skb_set_tail_pointer(skb, len);
                        goto fill;
                }
        }

        /* create a new skb, with the correct size (and tailpad) */
        skb2 = skb_copy_expand(skb, sizeof *hdr, 1, flags);
        dev_kfree_skb_any(skb);
        if (unlikely(!skb2))
                return skb2;
        skb = skb2;

        /* fill out the RNDIS header.  we won't bother trying to batch
         * packets; Linux minimizes wasted bandwidth through tx queues.
         */
fill:
        hdr = (void *) __skb_push(skb, sizeof *hdr);
        memset(hdr, 0, sizeof *hdr);
        hdr->msg_type = RNDIS_MSG_PACKET;
        hdr->msg_len = cpu_to_le32(skb->len);
        hdr->data_offset = cpu_to_le32(sizeof(*hdr) - 8);
        hdr->data_len = cpu_to_le32(len);

        /* FIXME make the last packet always be short ... */
        return skb;
}
EXPORT_SYMBOL_GPL(rndis_tx_fixup);


static const struct driver_info rndis_info = {
        .description =  "RNDIS device",
        .flags =        FLAG_ETHER | FLAG_FRAMING_RN | FLAG_NO_SETINT,
        .bind =         rndis_bind,
        .unbind =       rndis_unbind,
        .status =       rndis_status,
        .rx_fixup =     rndis_rx_fixup,
        .tx_fixup =     rndis_tx_fixup,
};

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

static const struct usb_device_id       products [] = {
{
        /* RNDIS is MSFT's un-official variant of CDC ACM */
        USB_INTERFACE_INFO(USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
        .driver_info = (unsigned long) &rndis_info,
}, {
        /* "ActiveSync" is an undocumented variant of RNDIS, used in WM5 */
        USB_INTERFACE_INFO(USB_CLASS_MISC, 1, 1),
        .driver_info = (unsigned long) &rndis_info,
}, {
        /* RNDIS for tethering */
        USB_INTERFACE_INFO(USB_CLASS_WIRELESS_CONTROLLER, 1, 3),
        .driver_info = (unsigned long) &rndis_info,
},
        { },            // END
};
MODULE_DEVICE_TABLE(usb, products);

static struct usb_driver rndis_driver = {
        .name =         "rndis_host",
        .id_table =     products,
        .probe =        usbnet_probe,
        .disconnect =   usbnet_disconnect,
        .suspend =      usbnet_suspend,
        .resume =       usbnet_resume,
};

static int __init rndis_init(void)
{
        return usb_register(&rndis_driver);
}
module_init(rndis_init);

static void __exit rndis_exit(void)
{
        usb_deregister(&rndis_driver);
}
module_exit(rndis_exit);

MODULE_AUTHOR("David Brownell");
MODULE_DESCRIPTION("USB Host side RNDIS driver");
MODULE_LICENSE("GPL");