/*
 * f_phonet.c -- USB CDC Phonet function
 *
 * Copyright (C) 2007-2008 Nokia Corporation. All rights reserved.
 *
 * Author: Rémi Denis-Courmont
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * 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., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/device.h>

#include <linux/netdevice.h>
#include <linux/if_ether.h>
#include <linux/if_phonet.h>
#include <linux/if_arp.h>

#include <linux/usb/ch9.h>
#include <linux/usb/cdc.h>
#include <linux/usb/composite.h>

#include "u_phonet.h"

#define PN_MEDIA_USB    0x1B
#define MAXPACKET       512
#if (PAGE_SIZE % MAXPACKET)
#error MAXPACKET must divide PAGE_SIZE!
#endif

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

struct phonet_port {
        struct f_phonet                 *usb;
        spinlock_t                      lock;
};

struct f_phonet {
        struct usb_function             function;
        struct {
                struct sk_buff          *skb;
                spinlock_t              lock;
        } rx;
        struct net_device               *dev;
        struct usb_ep                   *in_ep, *out_ep;

        struct usb_request              *in_req;
        struct usb_request              *out_reqv[0];
};

static int phonet_rxq_size = 17;

static inline struct f_phonet *func_to_pn(struct usb_function *f)
{
        return container_of(f, struct f_phonet, function);
}

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

#define USB_CDC_SUBCLASS_PHONET 0xfe
#define USB_CDC_PHONET_TYPE     0xab

static struct usb_interface_descriptor
pn_control_intf_desc = {
        .bLength =              sizeof pn_control_intf_desc,
        .bDescriptorType =      USB_DT_INTERFACE,

        /* .bInterfaceNumber =  DYNAMIC, */
        .bInterfaceClass =      USB_CLASS_COMM,
        .bInterfaceSubClass =   USB_CDC_SUBCLASS_PHONET,
};

static const struct usb_cdc_header_desc
pn_header_desc = {
        .bLength =              sizeof pn_header_desc,
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubType =   USB_CDC_HEADER_TYPE,
        .bcdCDC =               cpu_to_le16(0x0110),
};

static const struct usb_cdc_header_desc
pn_phonet_desc = {
        .bLength =              sizeof pn_phonet_desc,
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubType =   USB_CDC_PHONET_TYPE,
        .bcdCDC =               cpu_to_le16(0x1505), /* ??? */
};

static struct usb_cdc_union_desc
pn_union_desc = {
        .bLength =              sizeof pn_union_desc,
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubType =   USB_CDC_UNION_TYPE,

        /* .bMasterInterface0 = DYNAMIC, */
        /* .bSlaveInterface0 =  DYNAMIC, */
};

static struct usb_interface_descriptor
pn_data_nop_intf_desc = {
        .bLength =              sizeof pn_data_nop_intf_desc,
        .bDescriptorType =      USB_DT_INTERFACE,

        /* .bInterfaceNumber =  DYNAMIC, */
        .bAlternateSetting =    0,
        .bNumEndpoints =        0,
        .bInterfaceClass =      USB_CLASS_CDC_DATA,
};

static struct usb_interface_descriptor
pn_data_intf_desc = {
        .bLength =              sizeof pn_data_intf_desc,
        .bDescriptorType =      USB_DT_INTERFACE,

        /* .bInterfaceNumber =  DYNAMIC, */
        .bAlternateSetting =    1,
        .bNumEndpoints =        2,
        .bInterfaceClass =      USB_CLASS_CDC_DATA,
};

static struct usb_endpoint_descriptor
pn_fs_sink_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_OUT,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
};

static struct usb_endpoint_descriptor
pn_hs_sink_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_OUT,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(MAXPACKET),
};

static struct usb_endpoint_descriptor
pn_fs_source_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_IN,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
};

static struct usb_endpoint_descriptor
pn_hs_source_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_IN,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(512),
};

static struct usb_descriptor_header *fs_pn_function[] = {
        (struct usb_descriptor_header *) &pn_control_intf_desc,
        (struct usb_descriptor_header *) &pn_header_desc,
        (struct usb_descriptor_header *) &pn_phonet_desc,
        (struct usb_descriptor_header *) &pn_union_desc,
        (struct usb_descriptor_header *) &pn_data_nop_intf_desc,
        (struct usb_descriptor_header *) &pn_data_intf_desc,
        (struct usb_descriptor_header *) &pn_fs_sink_desc,
        (struct usb_descriptor_header *) &pn_fs_source_desc,
        NULL,
};

static struct usb_descriptor_header *hs_pn_function[] = {
        (struct usb_descriptor_header *) &pn_control_intf_desc,
        (struct usb_descriptor_header *) &pn_header_desc,
        (struct usb_descriptor_header *) &pn_phonet_desc,
        (struct usb_descriptor_header *) &pn_union_desc,
        (struct usb_descriptor_header *) &pn_data_nop_intf_desc,
        (struct usb_descriptor_header *) &pn_data_intf_desc,
        (struct usb_descriptor_header *) &pn_hs_sink_desc,
        (struct usb_descriptor_header *) &pn_hs_source_desc,
        NULL,
};

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

static int pn_net_open(struct net_device *dev)
{
        netif_wake_queue(dev);
        return 0;
}

static int pn_net_close(struct net_device *dev)
{
        netif_stop_queue(dev);
        return 0;
}

static void pn_tx_complete(struct usb_ep *ep, struct usb_request *req)
{
        struct f_phonet *fp = ep->driver_data;
        struct net_device *dev = fp->dev;
        struct sk_buff *skb = req->context;

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

        case -ESHUTDOWN: /* disconnected */
        case -ECONNRESET: /* disabled */
                dev->stats.tx_aborted_errors++;
        default:
                dev->stats.tx_errors++;
        }

        dev_kfree_skb_any(skb);
        netif_wake_queue(dev);
}

static int pn_net_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct phonet_port *port = netdev_priv(dev);
        struct f_phonet *fp;
        struct usb_request *req;
        unsigned long flags;

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

        spin_lock_irqsave(&port->lock, flags);
        fp = port->usb;
        if (unlikely(!fp)) /* race with carrier loss */
                goto out_unlock;

        req = fp->in_req;
        req->buf = skb->data;
        req->length = skb->len;
        req->complete = pn_tx_complete;
        req->zero = 1;
        req->context = skb;

        if (unlikely(usb_ep_queue(fp->in_ep, req, GFP_ATOMIC)))
                goto out_unlock;

        netif_stop_queue(dev);
        skb = NULL;

out_unlock:
        spin_unlock_irqrestore(&port->lock, flags);
out:
        if (unlikely(skb)) {
                dev_kfree_skb(skb);
                dev->stats.tx_dropped++;
        }
        return NETDEV_TX_OK;
}

static int pn_net_mtu(struct net_device *dev, int new_mtu)
{
        if ((new_mtu < PHONET_MIN_MTU) || (new_mtu > PHONET_MAX_MTU))
                return -EINVAL;
        dev->mtu = new_mtu;
        return 0;
}

static const struct net_device_ops pn_netdev_ops = {
        .ndo_open       = pn_net_open,
        .ndo_stop       = pn_net_close,
        .ndo_start_xmit = pn_net_xmit,
        .ndo_change_mtu = pn_net_mtu,
};

static void pn_net_setup(struct net_device *dev)
{
        dev->features           = 0;
        dev->type               = ARPHRD_PHONET;
        dev->flags              = IFF_POINTOPOINT | IFF_NOARP;
        dev->mtu                = PHONET_DEV_MTU;
        dev->hard_header_len    = 1;
        dev->dev_addr[0]        = PN_MEDIA_USB;
        dev->addr_len           = 1;
        dev->tx_queue_len       = 1;

        dev->netdev_ops         = &pn_netdev_ops;
        dev->destructor         = free_netdev;
        dev->header_ops         = &phonet_header_ops;
}

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

/*
 * Queue buffer for data from the host
 */
static int
pn_rx_submit(struct f_phonet *fp, struct usb_request *req, gfp_t gfp_flags)
{
        struct net_device *dev = fp->dev;
        struct page *page;
        int err;

        page = __netdev_alloc_page(dev, gfp_flags);
        if (!page)
                return -ENOMEM;

        req->buf = page_address(page);
        req->length = PAGE_SIZE;
        req->context = page;

        err = usb_ep_queue(fp->out_ep, req, gfp_flags);
        if (unlikely(err))
                netdev_free_page(dev, page);
        return err;
}

static void pn_rx_complete(struct usb_ep *ep, struct usb_request *req)
{
        struct f_phonet *fp = ep->driver_data;
        struct net_device *dev = fp->dev;
        struct page *page = req->context;
        struct sk_buff *skb;
        unsigned long flags;
        int status = req->status;

        switch (status) {
        case 0:
                spin_lock_irqsave(&fp->rx.lock, flags);
                skb = fp->rx.skb;
                if (!skb)
                        skb = fp->rx.skb = netdev_alloc_skb(dev, 12);
                if (req->actual < req->length) /* Last fragment */
                        fp->rx.skb = NULL;
                spin_unlock_irqrestore(&fp->rx.lock, flags);

                if (unlikely(!skb))
                        break;

                if (skb->len == 0) { /* First fragment */
                        skb->protocol = htons(ETH_P_PHONET);
                        skb_reset_mac_header(skb);
                        /* Can't use pskb_pull() on page in IRQ */
                        memcpy(skb_put(skb, 1), page_address(page), 1);
                }

                skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page,
                                skb->len == 0, req->actual);
                page = NULL;

                if (req->actual < req->length) { /* Last fragment */
                        skb->dev = dev;
                        dev->stats.rx_packets++;
                        dev->stats.rx_bytes += skb->len;

                        netif_rx(skb);
                }
                break;

        /* Do not resubmit in these cases: */
        case -ESHUTDOWN: /* disconnect */
        case -ECONNABORTED: /* hw reset */
        case -ECONNRESET: /* dequeued (unlink or netif down) */
                req = NULL;
                break;

        /* Do resubmit in these cases: */
        case -EOVERFLOW: /* request buffer overflow */
                dev->stats.rx_over_errors++;
        default:
                dev->stats.rx_errors++;
                break;
        }

        if (page)
                netdev_free_page(dev, page);
        if (req)
                pn_rx_submit(fp, req, GFP_ATOMIC);
}

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

static void __pn_reset(struct usb_function *f)
{
        struct f_phonet *fp = func_to_pn(f);
        struct net_device *dev = fp->dev;
        struct phonet_port *port = netdev_priv(dev);

        netif_carrier_off(dev);
        port->usb = NULL;

        usb_ep_disable(fp->out_ep);
        usb_ep_disable(fp->in_ep);
        if (fp->rx.skb) {
                dev_kfree_skb_irq(fp->rx.skb);
                fp->rx.skb = NULL;
        }
}

static int pn_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
{
        struct f_phonet *fp = func_to_pn(f);
        struct usb_gadget *gadget = fp->function.config->cdev->gadget;

        if (intf == pn_control_intf_desc.bInterfaceNumber)
                /* control interface, no altsetting */
                return (alt > 0) ? -EINVAL : 0;

        if (intf == pn_data_intf_desc.bInterfaceNumber) {
                struct net_device *dev = fp->dev;
                struct phonet_port *port = netdev_priv(dev);

                /* data intf (0: inactive, 1: active) */
                if (alt > 1)
                        return -EINVAL;

                spin_lock(&port->lock);
                __pn_reset(f);
                if (alt == 1) {
                        struct usb_endpoint_descriptor *out, *in;
                        int i;

                        out = ep_choose(gadget,
                                        &pn_hs_sink_desc,
                                        &pn_fs_sink_desc);
                        in = ep_choose(gadget,
                                        &pn_hs_source_desc,
                                        &pn_fs_source_desc);
                        usb_ep_enable(fp->out_ep, out);
                        usb_ep_enable(fp->in_ep, in);

                        port->usb = fp;
                        fp->out_ep->driver_data = fp;
                        fp->in_ep->driver_data = fp;

                        netif_carrier_on(dev);
                        for (i = 0; i < phonet_rxq_size; i++)
                                pn_rx_submit(fp, fp->out_reqv[i], GFP_ATOMIC);
                }
                spin_unlock(&port->lock);
                return 0;
        }

        return -EINVAL;
}

static int pn_get_alt(struct usb_function *f, unsigned intf)
{
        struct f_phonet *fp = func_to_pn(f);

        if (intf == pn_control_intf_desc.bInterfaceNumber)
                return 0;

        if (intf == pn_data_intf_desc.bInterfaceNumber) {
                struct phonet_port *port = netdev_priv(fp->dev);
                u8 alt;

                spin_lock(&port->lock);
                alt = port->usb != NULL;
                spin_unlock(&port->lock);
                return alt;
        }

        return -EINVAL;
}

static void pn_disconnect(struct usb_function *f)
{
        struct f_phonet *fp = func_to_pn(f);
        struct phonet_port *port = netdev_priv(fp->dev);
        unsigned long flags;

        /* remain disabled until set_alt */
        spin_lock_irqsave(&port->lock, flags);
        __pn_reset(f);
        spin_unlock_irqrestore(&port->lock, flags);
}

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

static __init
int pn_bind(struct usb_configuration *c, struct usb_function *f)
{
        struct usb_composite_dev *cdev = c->cdev;
        struct usb_gadget *gadget = cdev->gadget;
        struct f_phonet *fp = func_to_pn(f);
        struct usb_ep *ep;
        int status, i;

        /* Reserve interface IDs */
        status = usb_interface_id(c, f);
        if (status < 0)
                goto err;
        pn_control_intf_desc.bInterfaceNumber = status;
        pn_union_desc.bMasterInterface0 = status;

        status = usb_interface_id(c, f);
        if (status < 0)
                goto err;
        pn_data_nop_intf_desc.bInterfaceNumber = status;
        pn_data_intf_desc.bInterfaceNumber = status;
        pn_union_desc.bSlaveInterface0 = status;

        /* Reserve endpoints */
        status = -ENODEV;
        ep = usb_ep_autoconfig(gadget, &pn_fs_sink_desc);
        if (!ep)
                goto err;
        fp->out_ep = ep;
        ep->driver_data = fp; /* Claim */

        ep = usb_ep_autoconfig(gadget, &pn_fs_source_desc);
        if (!ep)
                goto err;
        fp->in_ep = ep;
        ep->driver_data = fp; /* Claim */

        pn_hs_sink_desc.bEndpointAddress =
                pn_fs_sink_desc.bEndpointAddress;
        pn_hs_source_desc.bEndpointAddress =
                pn_fs_source_desc.bEndpointAddress;

        /* Do not try to bind Phonet twice... */
        fp->function.descriptors = fs_pn_function;
        fp->function.hs_descriptors = hs_pn_function;

        /* Incoming USB requests */
        status = -ENOMEM;
        for (i = 0; i < phonet_rxq_size; i++) {
                struct usb_request *req;

                req = usb_ep_alloc_request(fp->out_ep, GFP_KERNEL);
                if (!req)
                        goto err;

                req->complete = pn_rx_complete;
                fp->out_reqv[i] = req;
        }

        /* Outgoing USB requests */
        fp->in_req = usb_ep_alloc_request(fp->in_ep, GFP_KERNEL);
        if (!fp->in_req)
                goto err;

        INFO(cdev, "USB CDC Phonet function\n");
        INFO(cdev, "using %s, OUT %s, IN %s\n", cdev->gadget->name,
                fp->out_ep->name, fp->in_ep->name);
        return 0;

err:
        if (fp->out_ep)
                fp->out_ep->driver_data = NULL;
        if (fp->in_ep)
                fp->in_ep->driver_data = NULL;
        ERROR(cdev, "USB CDC Phonet: cannot autoconfigure\n");
        return status;
}

static void
pn_unbind(struct usb_configuration *c, struct usb_function *f)
{
        struct f_phonet *fp = func_to_pn(f);
        int i;

        /* We are already disconnected */
        if (fp->in_req)
                usb_ep_free_request(fp->in_ep, fp->in_req);
        for (i = 0; i < phonet_rxq_size; i++)
                if (fp->out_reqv[i])
                        usb_ep_free_request(fp->out_ep, fp->out_reqv[i]);

        kfree(fp);
}

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

static struct net_device *dev;

int __init phonet_bind_config(struct usb_configuration *c)
{
        struct f_phonet *fp;
        int err, size;

        size = sizeof(*fp) + (phonet_rxq_size * sizeof(struct usb_request *));
        fp = kzalloc(size, GFP_KERNEL);
        if (!fp)
                return -ENOMEM;

        fp->dev = dev;
        fp->function.name = "phonet";
        fp->function.bind = pn_bind;
        fp->function.unbind = pn_unbind;
        fp->function.set_alt = pn_set_alt;
        fp->function.get_alt = pn_get_alt;
        fp->function.disable = pn_disconnect;
        spin_lock_init(&fp->rx.lock);

        err = usb_add_function(c, &fp->function);
        if (err)
                kfree(fp);
        return err;
}

int __init gphonet_setup(struct usb_gadget *gadget)
{
        struct phonet_port *port;
        int err;

        /* Create net device */
        BUG_ON(dev);
        dev = alloc_netdev(sizeof(*port), "upnlink%d", pn_net_setup);
        if (!dev)
                return -ENOMEM;

        port = netdev_priv(dev);
        spin_lock_init(&port->lock);
        netif_carrier_off(dev);
        SET_NETDEV_DEV(dev, &gadget->dev);

        err = register_netdev(dev);
        if (err)
                free_netdev(dev);
        return err;
}

void gphonet_cleanup(void)
{
        unregister_netdev(dev);
}