printer.c

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/*
 * printer.c -- Printer gadget driver
 *
 * Copyright (C) 2003-2005 David Brownell
 * Copyright (C) 2006 Craig W. Nadler
 *
 * 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.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/timer.h>
#include <linux/list.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/moduleparam.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/types.h>
#include <linux/ctype.h>
#include <linux/cdev.h>

#include <asm/byteorder.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/uaccess.h>
#include <asm/unaligned.h>

#include <linux/usb/ch9.h>
#include <linux/usb/composite.h>
#include <linux/usb/gadget.h>
#include <linux/usb/g_printer.h>

#include "gadget_chips.h"

USB_GADGET_COMPOSITE_OPTIONS();

#define DRIVER_DESC     "Printer Gadget"
#define DRIVER_VERSION      "2007 OCT 06"

static DEFINE_MUTEX(printer_mutex);
static const char shortname [] = "printer";
static const char driver_desc [] = DRIVER_DESC;

static dev_t g_printer_devno;

static struct class *usb_gadget_class;

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

struct printer_dev {
    spinlock_t      lock;       /* lock this structure */
    /* lock buffer lists during read/write calls */
    struct mutex        lock_printer_io;
    struct usb_gadget   *gadget;
    s8          interface;
    struct usb_ep       *in_ep, *out_ep;

    struct list_head    rx_reqs;    /* List of free RX structs */
    struct list_head    rx_reqs_active; /* List of Active RX xfers */
    struct list_head    rx_buffers; /* List of completed xfers */
    /* wait until there is data to be read. */
    wait_queue_head_t   rx_wait;
    struct list_head    tx_reqs;    /* List of free TX structs */
    struct list_head    tx_reqs_active; /* List of Active TX xfers */
    /* Wait until there are write buffers available to use. */
    wait_queue_head_t   tx_wait;
    /* Wait until all write buffers have been sent. */
    wait_queue_head_t   tx_flush_wait;
    struct usb_request  *current_rx_req;
    size_t          current_rx_bytes;
    u8          *current_rx_buf;
    u8          printer_status;
    u8          reset_printer;
    struct cdev     printer_cdev;
    struct device       *pdev;
    u8          printer_cdev_open;
    wait_queue_head_t   wait;
    struct usb_function function;
};

static struct printer_dev usb_printer_gadget;

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

/* DO NOT REUSE THESE IDs with a protocol-incompatible driver!!  Ever!!
 * Instead:  allocate your own, using normal USB-IF procedures.
 */

/* Thanks to NetChip Technologies for donating this product ID.
 */
#define PRINTER_VENDOR_NUM  0x0525      /* NetChip */
#define PRINTER_PRODUCT_NUM 0xa4a8      /* Linux-USB Printer Gadget */

/* Some systems will want different product identifiers published in the
 * device descriptor, either numbers or strings or both.  These string
 * parameters are in UTF-8 (superset of ASCII's 7 bit characters).
 */

module_param_named(iSerialNum, coverwrite.serial_number, charp, S_IRUGO);
MODULE_PARM_DESC(iSerialNum, "1");

static char *iPNPstring;
module_param(iPNPstring, charp, S_IRUGO);
MODULE_PARM_DESC(iPNPstring, "MFG:linux;MDL:g_printer;CLS:PRINTER;SN:1;");

/* Number of requests to allocate per endpoint, not used for ep0. */
static unsigned qlen = 10;
module_param(qlen, uint, S_IRUGO|S_IWUSR);

#define QLEN    qlen

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

/*
 * DESCRIPTORS ... most are static, but strings and (full) configuration
 * descriptors are built on demand.
 */

/* holds our biggest descriptor */
#define USB_DESC_BUFSIZE        256
#define USB_BUFSIZE         8192

static struct usb_device_descriptor device_desc = {
    .bLength =      sizeof device_desc,
    .bDescriptorType =  USB_DT_DEVICE,
    .bcdUSB =       cpu_to_le16(0x0200),
    .bDeviceClass =     USB_CLASS_PER_INTERFACE,
    .bDeviceSubClass =  0,
    .bDeviceProtocol =  0,
    .idVendor =     cpu_to_le16(PRINTER_VENDOR_NUM),
    .idProduct =        cpu_to_le16(PRINTER_PRODUCT_NUM),
    .bNumConfigurations =   1
};

static struct usb_interface_descriptor intf_desc = {
    .bLength =      sizeof intf_desc,
    .bDescriptorType =  USB_DT_INTERFACE,
    .bNumEndpoints =    2,
    .bInterfaceClass =  USB_CLASS_PRINTER,
    .bInterfaceSubClass =   1,  /* Printer Sub-Class */
    .bInterfaceProtocol =   2,  /* Bi-Directional */
    .iInterface =       0
};

static struct usb_endpoint_descriptor fs_ep_in_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK
};

static struct usb_endpoint_descriptor fs_ep_out_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bEndpointAddress = USB_DIR_OUT,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK
};

static struct usb_descriptor_header *fs_printer_function[] = {
    (struct usb_descriptor_header *) &intf_desc,
    (struct usb_descriptor_header *) &fs_ep_in_desc,
    (struct usb_descriptor_header *) &fs_ep_out_desc,
    NULL
};

/*
 * usb 2.0 devices need to expose both high speed and full speed
 * descriptors, unless they only run at full speed.
 */

static struct usb_endpoint_descriptor hs_ep_in_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
    .wMaxPacketSize =   cpu_to_le16(512)
};

static struct usb_endpoint_descriptor hs_ep_out_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
    .wMaxPacketSize =   cpu_to_le16(512)
};

static struct usb_qualifier_descriptor dev_qualifier = {
    .bLength =      sizeof dev_qualifier,
    .bDescriptorType =  USB_DT_DEVICE_QUALIFIER,
    .bcdUSB =       cpu_to_le16(0x0200),
    .bDeviceClass =     USB_CLASS_PRINTER,
    .bNumConfigurations =   1
};

static struct usb_descriptor_header *hs_printer_function[] = {
    (struct usb_descriptor_header *) &intf_desc,
    (struct usb_descriptor_header *) &hs_ep_in_desc,
    (struct usb_descriptor_header *) &hs_ep_out_desc,
    NULL
};

static struct usb_otg_descriptor otg_descriptor = {
    .bLength =              sizeof otg_descriptor,
    .bDescriptorType =      USB_DT_OTG,
    .bmAttributes =         USB_OTG_SRP,
};

static const struct usb_descriptor_header *otg_desc[] = {
    (struct usb_descriptor_header *) &otg_descriptor,
    NULL,
};

/* maxpacket and other transfer characteristics vary by speed. */
#define ep_desc(g, hs, fs) (((g)->speed == USB_SPEED_HIGH)?(hs):(fs))

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

/* descriptors that are built on-demand */

static char             product_desc [40] = DRIVER_DESC;
static char             serial_num [40] = "1";
static char             pnp_string [1024] =
    "XXMFG:linux;MDL:g_printer;CLS:PRINTER;SN:1;";

/* static strings, in UTF-8 */
static struct usb_string        strings [] = {
    [USB_GADGET_MANUFACTURER_IDX].s = "",
    [USB_GADGET_PRODUCT_IDX].s = product_desc,
    [USB_GADGET_SERIAL_IDX].s = serial_num,
    {  }        /* end of list */
};

static struct usb_gadget_strings    stringtab_dev = {
    .language   = 0x0409,   /* en-us */
    .strings    = strings,
};

static struct usb_gadget_strings *dev_strings[] = {
    &stringtab_dev,
    NULL,
};

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

static struct usb_request *
printer_req_alloc(struct usb_ep *ep, unsigned len, gfp_t gfp_flags)
{
    struct usb_request  *req;

    req = usb_ep_alloc_request(ep, gfp_flags);

    if (req != NULL) {
        req->length = len;
        req->buf = kmalloc(len, gfp_flags);
        if (req->buf == NULL) {
            usb_ep_free_request(ep, req);
            return NULL;
        }
    }

    return req;
}

static void
printer_req_free(struct usb_ep *ep, struct usb_request *req)
{
    if (ep != NULL && req != NULL) {
        kfree(req->buf);
        usb_ep_free_request(ep, req);
    }
}

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

static void rx_complete(struct usb_ep *ep, struct usb_request *req)
{
    struct printer_dev  *dev = ep->driver_data;
    int         status = req->status;
    unsigned long       flags;

    spin_lock_irqsave(&dev->lock, flags);

    list_del_init(&req->list);  /* Remode from Active List */

    switch (status) {

    /* normal completion */
    case 0:
        if (req->actual > 0) {
            list_add_tail(&req->list, &dev->rx_buffers);
            DBG(dev, "G_Printer : rx length %d\n", req->actual);
        } else {
            list_add(&req->list, &dev->rx_reqs);
        }
        break;

    /* software-driven interface shutdown */
    case -ECONNRESET:       /* unlink */
    case -ESHUTDOWN:        /* disconnect etc */
        VDBG(dev, "rx shutdown, code %d\n", status);
        list_add(&req->list, &dev->rx_reqs);
        break;

    /* for hardware automagic (such as pxa) */
    case -ECONNABORTED:     /* endpoint reset */
        DBG(dev, "rx %s reset\n", ep->name);
        list_add(&req->list, &dev->rx_reqs);
        break;

    /* data overrun */
    case -EOVERFLOW:
        /* FALLTHROUGH */

    default:
        DBG(dev, "rx status %d\n", status);
        list_add(&req->list, &dev->rx_reqs);
        break;
    }

    wake_up_interruptible(&dev->rx_wait);
    spin_unlock_irqrestore(&dev->lock, flags);
}

static void tx_complete(struct usb_ep *ep, struct usb_request *req)
{
    struct printer_dev  *dev = ep->driver_data;

    switch (req->status) {
    default:
        VDBG(dev, "tx err %d\n", req->status);
        /* FALLTHROUGH */
    case -ECONNRESET:       /* unlink */
    case -ESHUTDOWN:        /* disconnect etc */
        break;
    case 0:
        break;
    }

    spin_lock(&dev->lock);
    /* Take the request struct off the active list and put it on the
     * free list.
     */
    list_del_init(&req->list);
    list_add(&req->list, &dev->tx_reqs);
    wake_up_interruptible(&dev->tx_wait);
    if (likely(list_empty(&dev->tx_reqs_active)))
        wake_up_interruptible(&dev->tx_flush_wait);

    spin_unlock(&dev->lock);
}

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

static int
printer_open(struct inode *inode, struct file *fd)
{
    struct printer_dev  *dev;
    unsigned long       flags;
    int         ret = -EBUSY;

    mutex_lock(&printer_mutex);
    dev = container_of(inode->i_cdev, struct printer_dev, printer_cdev);

    spin_lock_irqsave(&dev->lock, flags);

    if (!dev->printer_cdev_open) {
        dev->printer_cdev_open = 1;
        fd->private_data = dev;
        ret = 0;
        /* Change the printer status to show that it's on-line. */
        dev->printer_status |= PRINTER_SELECTED;
    }

    spin_unlock_irqrestore(&dev->lock, flags);

    DBG(dev, "printer_open returned %x\n", ret);
    mutex_unlock(&printer_mutex);
    return ret;
}

static int
printer_close(struct inode *inode, struct file *fd)
{
    struct printer_dev  *dev = fd->private_data;
    unsigned long       flags;

    spin_lock_irqsave(&dev->lock, flags);
    dev->printer_cdev_open = 0;
    fd->private_data = NULL;
    /* Change printer status to show that the printer is off-line. */
    dev->printer_status &= ~PRINTER_SELECTED;
    spin_unlock_irqrestore(&dev->lock, flags);

    DBG(dev, "printer_close\n");

    return 0;
}

/* This function must be called with interrupts turned off. */
static void
setup_rx_reqs(struct printer_dev *dev)
{
    struct usb_request              *req;

    while (likely(!list_empty(&dev->rx_reqs))) {
        int error;

        req = container_of(dev->rx_reqs.next,
                struct usb_request, list);
        list_del_init(&req->list);

        /* The USB Host sends us whatever amount of data it wants to
         * so we always set the length field to the full USB_BUFSIZE.
         * If the amount of data is more than the read() caller asked
         * for it will be stored in the request buffer until it is
         * asked for by read().
         */
        req->length = USB_BUFSIZE;
        req->complete = rx_complete;

        error = usb_ep_queue(dev->out_ep, req, GFP_ATOMIC);
        if (error) {
            DBG(dev, "rx submit --> %d\n", error);
            list_add(&req->list, &dev->rx_reqs);
            break;
        } else {
            list_add(&req->list, &dev->rx_reqs_active);
        }
    }
}

static ssize_t
printer_read(struct file *fd, char __user *buf, size_t len, loff_t *ptr)
{
    struct printer_dev      *dev = fd->private_data;
    unsigned long           flags;
    size_t              size;
    size_t              bytes_copied;
    struct usb_request      *req;
    /* This is a pointer to the current USB rx request. */
    struct usb_request      *current_rx_req;
    /* This is the number of bytes in the current rx buffer. */
    size_t              current_rx_bytes;
    /* This is a pointer to the current rx buffer. */
    u8              *current_rx_buf;

    if (len == 0)
        return -EINVAL;

    DBG(dev, "printer_read trying to read %d bytes\n", (int)len);

    mutex_lock(&dev->lock_printer_io);
    spin_lock_irqsave(&dev->lock, flags);

    /* We will use this flag later to check if a printer reset happened
     * after we turn interrupts back on.
     */
    dev->reset_printer = 0;

    setup_rx_reqs(dev);

    bytes_copied = 0;
    current_rx_req = dev->current_rx_req;
    current_rx_bytes = dev->current_rx_bytes;
    current_rx_buf = dev->current_rx_buf;
    dev->current_rx_req = NULL;
    dev->current_rx_bytes = 0;
    dev->current_rx_buf = NULL;

    /* Check if there is any data in the read buffers. Please note that
     * current_rx_bytes is the number of bytes in the current rx buffer.
     * If it is zero then check if there are any other rx_buffers that
     * are on the completed list. We are only out of data if all rx
     * buffers are empty.
     */
    if ((current_rx_bytes == 0) &&
            (likely(list_empty(&dev->rx_buffers)))) {
        /* Turn interrupts back on before sleeping. */
        spin_unlock_irqrestore(&dev->lock, flags);

        /*
         * If no data is available check if this is a NON-Blocking
         * call or not.
         */
        if (fd->f_flags & (O_NONBLOCK|O_NDELAY)) {
            mutex_unlock(&dev->lock_printer_io);
            return -EAGAIN;
        }

        /* Sleep until data is available */
        wait_event_interruptible(dev->rx_wait,
                (likely(!list_empty(&dev->rx_buffers))));
        spin_lock_irqsave(&dev->lock, flags);
    }

    /* We have data to return then copy it to the caller's buffer.*/
    while ((current_rx_bytes || likely(!list_empty(&dev->rx_buffers)))
            && len) {
        if (current_rx_bytes == 0) {
            req = container_of(dev->rx_buffers.next,
                    struct usb_request, list);
            list_del_init(&req->list);

            if (req->actual && req->buf) {
                current_rx_req = req;
                current_rx_bytes = req->actual;
                current_rx_buf = req->buf;
            } else {
                list_add(&req->list, &dev->rx_reqs);
                continue;
            }
        }

        /* Don't leave irqs off while doing memory copies */
        spin_unlock_irqrestore(&dev->lock, flags);

        if (len > current_rx_bytes)
            size = current_rx_bytes;
        else
            size = len;

        size -= copy_to_user(buf, current_rx_buf, size);
        bytes_copied += size;
        len -= size;
        buf += size;

        spin_lock_irqsave(&dev->lock, flags);

        /* We've disconnected or reset so return. */
        if (dev->reset_printer) {
            list_add(&current_rx_req->list, &dev->rx_reqs);
            spin_unlock_irqrestore(&dev->lock, flags);
            mutex_unlock(&dev->lock_printer_io);
            return -EAGAIN;
        }

        /* If we not returning all the data left in this RX request
         * buffer then adjust the amount of data left in the buffer.
         * Othewise if we are done with this RX request buffer then
         * requeue it to get any incoming data from the USB host.
         */
        if (size < current_rx_bytes) {
            current_rx_bytes -= size;
            current_rx_buf += size;
        } else {
            list_add(&current_rx_req->list, &dev->rx_reqs);
            current_rx_bytes = 0;
            current_rx_buf = NULL;
            current_rx_req = NULL;
        }
    }

    dev->current_rx_req = current_rx_req;
    dev->current_rx_bytes = current_rx_bytes;
    dev->current_rx_buf = current_rx_buf;

    spin_unlock_irqrestore(&dev->lock, flags);
    mutex_unlock(&dev->lock_printer_io);

    DBG(dev, "printer_read returned %d bytes\n", (int)bytes_copied);

    if (bytes_copied)
        return bytes_copied;
    else
        return -EAGAIN;
}

static ssize_t
printer_write(struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
{
    struct printer_dev  *dev = fd->private_data;
    unsigned long       flags;
    size_t          size;   /* Amount of data in a TX request. */
    size_t          bytes_copied = 0;
    struct usb_request  *req;

    DBG(dev, "printer_write trying to send %d bytes\n", (int)len);

    if (len == 0)
        return -EINVAL;

    mutex_lock(&dev->lock_printer_io);
    spin_lock_irqsave(&dev->lock, flags);

    /* Check if a printer reset happens while we have interrupts on */
    dev->reset_printer = 0;

    /* Check if there is any available write buffers */
    if (likely(list_empty(&dev->tx_reqs))) {
        /* Turn interrupts back on before sleeping. */
        spin_unlock_irqrestore(&dev->lock, flags);

        /*
         * If write buffers are available check if this is
         * a NON-Blocking call or not.
         */
        if (fd->f_flags & (O_NONBLOCK|O_NDELAY)) {
            mutex_unlock(&dev->lock_printer_io);
            return -EAGAIN;
        }

        /* Sleep until a write buffer is available */
        wait_event_interruptible(dev->tx_wait,
                (likely(!list_empty(&dev->tx_reqs))));
        spin_lock_irqsave(&dev->lock, flags);
    }

    while (likely(!list_empty(&dev->tx_reqs)) && len) {

        if (len > USB_BUFSIZE)
            size = USB_BUFSIZE;
        else
            size = len;

        req = container_of(dev->tx_reqs.next, struct usb_request,
                list);
        list_del_init(&req->list);

        req->complete = tx_complete;
        req->length = size;

        /* Check if we need to send a zero length packet. */
        if (len > size)
            /* They will be more TX requests so no yet. */
            req->zero = 0;
        else
            /* If the data amount is not a multple of the
             * maxpacket size then send a zero length packet.
             */
            req->zero = ((len % dev->in_ep->maxpacket) == 0);

        /* Don't leave irqs off while doing memory copies */
        spin_unlock_irqrestore(&dev->lock, flags);

        if (copy_from_user(req->buf, buf, size)) {
            list_add(&req->list, &dev->tx_reqs);
            mutex_unlock(&dev->lock_printer_io);
            return bytes_copied;
        }

        bytes_copied += size;
        len -= size;
        buf += size;

        spin_lock_irqsave(&dev->lock, flags);

        /* We've disconnected or reset so free the req and buffer */
        if (dev->reset_printer) {
            list_add(&req->list, &dev->tx_reqs);
            spin_unlock_irqrestore(&dev->lock, flags);
            mutex_unlock(&dev->lock_printer_io);
            return -EAGAIN;
        }

        if (usb_ep_queue(dev->in_ep, req, GFP_ATOMIC)) {
            list_add(&req->list, &dev->tx_reqs);
            spin_unlock_irqrestore(&dev->lock, flags);
            mutex_unlock(&dev->lock_printer_io);
            return -EAGAIN;
        }

        list_add(&req->list, &dev->tx_reqs_active);

    }

    spin_unlock_irqrestore(&dev->lock, flags);
    mutex_unlock(&dev->lock_printer_io);

    DBG(dev, "printer_write sent %d bytes\n", (int)bytes_copied);

    if (bytes_copied) {
        return bytes_copied;
    } else {
        return -EAGAIN;
    }
}

static int
printer_fsync(struct file *fd, loff_t start, loff_t end, int datasync)
{
    struct printer_dev  *dev = fd->private_data;
    struct inode *inode = fd->f_path.dentry->d_inode;
    unsigned long       flags;
    int         tx_list_empty;

    mutex_lock(&inode->i_mutex);
    spin_lock_irqsave(&dev->lock, flags);
    tx_list_empty = (likely(list_empty(&dev->tx_reqs)));
    spin_unlock_irqrestore(&dev->lock, flags);

    if (!tx_list_empty) {
        /* Sleep until all data has been sent */
        wait_event_interruptible(dev->tx_flush_wait,
                (likely(list_empty(&dev->tx_reqs_active))));
    }
    mutex_unlock(&inode->i_mutex);

    return 0;
}

static unsigned int
printer_poll(struct file *fd, poll_table *wait)
{
    struct printer_dev  *dev = fd->private_data;
    unsigned long       flags;
    int         status = 0;

    mutex_lock(&dev->lock_printer_io);
    spin_lock_irqsave(&dev->lock, flags);
    setup_rx_reqs(dev);
    spin_unlock_irqrestore(&dev->lock, flags);
    mutex_unlock(&dev->lock_printer_io);

    poll_wait(fd, &dev->rx_wait, wait);
    poll_wait(fd, &dev->tx_wait, wait);

    spin_lock_irqsave(&dev->lock, flags);
    if (likely(!list_empty(&dev->tx_reqs)))
        status |= POLLOUT | POLLWRNORM;

    if (likely(dev->current_rx_bytes) ||
            likely(!list_empty(&dev->rx_buffers)))
        status |= POLLIN | POLLRDNORM;

    spin_unlock_irqrestore(&dev->lock, flags);

    return status;
}

static long
printer_ioctl(struct file *fd, unsigned int code, unsigned long arg)
{
    struct printer_dev  *dev = fd->private_data;
    unsigned long       flags;
    int         status = 0;

    DBG(dev, "printer_ioctl: cmd=0x%4.4x, arg=%lu\n", code, arg);

    /* handle ioctls */

    spin_lock_irqsave(&dev->lock, flags);

    switch (code) {
    case GADGET_GET_PRINTER_STATUS:
        status = (int)dev->printer_status;
        break;
    case GADGET_SET_PRINTER_STATUS:
        dev->printer_status = (u8)arg;
        break;
    default:
        /* could not handle ioctl */
        DBG(dev, "printer_ioctl: ERROR cmd=0x%4.4xis not supported\n",
                code);
        status = -ENOTTY;
    }

    spin_unlock_irqrestore(&dev->lock, flags);

    return status;
}

/* used after endpoint configuration */
static const struct file_operations printer_io_operations = {
    .owner =    THIS_MODULE,
    .open =     printer_open,
    .read =     printer_read,
    .write =    printer_write,
    .fsync =    printer_fsync,
    .poll =     printer_poll,
    .unlocked_ioctl = printer_ioctl,
    .release =  printer_close,
    .llseek =   noop_llseek,
};

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

static int
set_printer_interface(struct printer_dev *dev)
{
    int         result = 0;

    dev->in_ep->desc = ep_desc(dev->gadget, &hs_ep_in_desc, &fs_ep_in_desc);
    dev->in_ep->driver_data = dev;

    dev->out_ep->desc = ep_desc(dev->gadget, &hs_ep_out_desc,
                    &fs_ep_out_desc);
    dev->out_ep->driver_data = dev;

    result = usb_ep_enable(dev->in_ep);
    if (result != 0) {
        DBG(dev, "enable %s --> %d\n", dev->in_ep->name, result);
        goto done;
    }

    result = usb_ep_enable(dev->out_ep);
    if (result != 0) {
        DBG(dev, "enable %s --> %d\n", dev->in_ep->name, result);
        goto done;
    }

done:
    /* on error, disable any endpoints  */
    if (result != 0) {
        (void) usb_ep_disable(dev->in_ep);
        (void) usb_ep_disable(dev->out_ep);
        dev->in_ep->desc = NULL;
        dev->out_ep->desc = NULL;
    }

    /* caller is responsible for cleanup on error */
    return result;
}

static void printer_reset_interface(struct printer_dev *dev)
{
    if (dev->interface < 0)
        return;

    DBG(dev, "%s\n", __func__);

    if (dev->in_ep->desc)
        usb_ep_disable(dev->in_ep);

    if (dev->out_ep->desc)
        usb_ep_disable(dev->out_ep);

    dev->in_ep->desc = NULL;
    dev->out_ep->desc = NULL;
    dev->interface = -1;
}

/* Change our operational Interface. */
static int set_interface(struct printer_dev *dev, unsigned number)
{
    int         result = 0;

    /* Free the current interface */
    printer_reset_interface(dev);

    result = set_printer_interface(dev);
    if (result)
        printer_reset_interface(dev);
    else
        dev->interface = number;

    if (!result)
        INFO(dev, "Using interface %x\n", number);

    return result;
}

static void printer_soft_reset(struct printer_dev *dev)
{
    struct usb_request  *req;

    INFO(dev, "Received Printer Reset Request\n");

    if (usb_ep_disable(dev->in_ep))
        DBG(dev, "Failed to disable USB in_ep\n");
    if (usb_ep_disable(dev->out_ep))
        DBG(dev, "Failed to disable USB out_ep\n");

    if (dev->current_rx_req != NULL) {
        list_add(&dev->current_rx_req->list, &dev->rx_reqs);
        dev->current_rx_req = NULL;
    }
    dev->current_rx_bytes = 0;
    dev->current_rx_buf = NULL;
    dev->reset_printer = 1;

    while (likely(!(list_empty(&dev->rx_buffers)))) {
        req = container_of(dev->rx_buffers.next, struct usb_request,
                list);
        list_del_init(&req->list);
        list_add(&req->list, &dev->rx_reqs);
    }

    while (likely(!(list_empty(&dev->rx_reqs_active)))) {
        req = container_of(dev->rx_buffers.next, struct usb_request,
                list);
        list_del_init(&req->list);
        list_add(&req->list, &dev->rx_reqs);
    }

    while (likely(!(list_empty(&dev->tx_reqs_active)))) {
        req = container_of(dev->tx_reqs_active.next,
                struct usb_request, list);
        list_del_init(&req->list);
        list_add(&req->list, &dev->tx_reqs);
    }

    if (usb_ep_enable(dev->in_ep))
        DBG(dev, "Failed to enable USB in_ep\n");
    if (usb_ep_enable(dev->out_ep))
        DBG(dev, "Failed to enable USB out_ep\n");

    wake_up_interruptible(&dev->rx_wait);
    wake_up_interruptible(&dev->tx_wait);
    wake_up_interruptible(&dev->tx_flush_wait);
}

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

/*
 * The setup() callback implements all the ep0 functionality that's not
 * handled lower down.
 */
static int printer_func_setup(struct usb_function *f,
        const struct usb_ctrlrequest *ctrl)
{
    struct printer_dev *dev = container_of(f, struct printer_dev, function);
    struct usb_composite_dev *cdev = f->config->cdev;
    struct usb_request  *req = cdev->req;
    int         value = -EOPNOTSUPP;
    u16         wIndex = le16_to_cpu(ctrl->wIndex);
    u16         wValue = le16_to_cpu(ctrl->wValue);
    u16         wLength = le16_to_cpu(ctrl->wLength);

    DBG(dev, "ctrl req%02x.%02x v%04x i%04x l%d\n",
        ctrl->bRequestType, ctrl->bRequest, wValue, wIndex, wLength);

    switch (ctrl->bRequestType&USB_TYPE_MASK) {
    case USB_TYPE_CLASS:
        switch (ctrl->bRequest) {
        case 0: /* Get the IEEE-1284 PNP String */
            /* Only one printer interface is supported. */
            if ((wIndex>>8) != dev->interface)
                break;

            value = (pnp_string[0]<<8)|pnp_string[1];
            memcpy(req->buf, pnp_string, value);
            DBG(dev, "1284 PNP String: %x %s\n", value,
                    &pnp_string[2]);
            break;

        case 1: /* Get Port Status */
            /* Only one printer interface is supported. */
            if (wIndex != dev->interface)
                break;

            *(u8 *)req->buf = dev->printer_status;
            value = min(wLength, (u16) 1);
            break;

        case 2: /* Soft Reset */
            /* Only one printer interface is supported. */
            if (wIndex != dev->interface)
                break;

            printer_soft_reset(dev);

            value = 0;
            break;

        default:
            goto unknown;
        }
        break;

    default:
unknown:
        VDBG(dev,
            "unknown ctrl req%02x.%02x v%04x i%04x l%d\n",
            ctrl->bRequestType, ctrl->bRequest,
            wValue, wIndex, wLength);
        break;
    }
    /* host either stalls (value < 0) or reports success */
    return value;
}

static int __init printer_func_bind(struct usb_configuration *c,
        struct usb_function *f)
{
    struct printer_dev *dev = container_of(f, struct printer_dev, function);
    struct usb_composite_dev *cdev = c->cdev;
    struct usb_ep       *in_ep, *out_ep;
    int id;

    id = usb_interface_id(c, f);
    if (id < 0)
        return id;
    intf_desc.bInterfaceNumber = id;

    /* all we really need is bulk IN/OUT */
    in_ep = usb_ep_autoconfig(cdev->gadget, &fs_ep_in_desc);
    if (!in_ep) {
autoconf_fail:
        dev_err(&cdev->gadget->dev, "can't autoconfigure on %s\n",
            cdev->gadget->name);
        return -ENODEV;
    }
    in_ep->driver_data = in_ep; /* claim */

    out_ep = usb_ep_autoconfig(cdev->gadget, &fs_ep_out_desc);
    if (!out_ep)
        goto autoconf_fail;
    out_ep->driver_data = out_ep;   /* claim */

    /* assumes that all endpoints are dual-speed */
    hs_ep_in_desc.bEndpointAddress = fs_ep_in_desc.bEndpointAddress;
    hs_ep_out_desc.bEndpointAddress = fs_ep_out_desc.bEndpointAddress;

    dev->in_ep = in_ep;
    dev->out_ep = out_ep;
    return 0;
}

static void printer_func_unbind(struct usb_configuration *c,
        struct usb_function *f)
{
}

static int printer_func_set_alt(struct usb_function *f,
        unsigned intf, unsigned alt)
{
    struct printer_dev *dev = container_of(f, struct printer_dev, function);
    int ret = -ENOTSUPP;

    if (!alt)
        ret = set_interface(dev, intf);

    return ret;
}

static void printer_func_disable(struct usb_function *f)
{
    struct printer_dev *dev = container_of(f, struct printer_dev, function);
    unsigned long       flags;

    DBG(dev, "%s\n", __func__);

    spin_lock_irqsave(&dev->lock, flags);
    printer_reset_interface(dev);
    spin_unlock_irqrestore(&dev->lock, flags);
}

static void printer_cfg_unbind(struct usb_configuration *c)
{
    struct printer_dev  *dev;
    struct usb_request  *req;

    dev = &usb_printer_gadget;

    DBG(dev, "%s\n", __func__);

    /* Remove sysfs files */
    device_destroy(usb_gadget_class, g_printer_devno);

    /* Remove Character Device */
    cdev_del(&dev->printer_cdev);

    /* we must already have been disconnected ... no i/o may be active */
    WARN_ON(!list_empty(&dev->tx_reqs_active));
    WARN_ON(!list_empty(&dev->rx_reqs_active));

    /* Free all memory for this driver. */
    while (!list_empty(&dev->tx_reqs)) {
        req = container_of(dev->tx_reqs.next, struct usb_request,
                list);
        list_del(&req->list);
        printer_req_free(dev->in_ep, req);
    }

    if (dev->current_rx_req != NULL)
        printer_req_free(dev->out_ep, dev->current_rx_req);

    while (!list_empty(&dev->rx_reqs)) {
        req = container_of(dev->rx_reqs.next,
                struct usb_request, list);
        list_del(&req->list);
        printer_req_free(dev->out_ep, req);
    }

    while (!list_empty(&dev->rx_buffers)) {
        req = container_of(dev->rx_buffers.next,
                struct usb_request, list);
        list_del(&req->list);
        printer_req_free(dev->out_ep, req);
    }
}

static struct usb_configuration printer_cfg_driver = {
    .label          = "printer",
    .unbind         = printer_cfg_unbind,
    .bConfigurationValue    = 1,
    .bmAttributes       = USB_CONFIG_ATT_ONE | USB_CONFIG_ATT_SELFPOWER,
};

static int __init printer_bind_config(struct usb_configuration *c)
{
    struct usb_gadget   *gadget = c->cdev->gadget;
    struct printer_dev  *dev;
    int         status = -ENOMEM;
    size_t          len;
    u32         i;
    struct usb_request  *req;

    usb_ep_autoconfig_reset(gadget);

    dev = &usb_printer_gadget;

    dev->function.name = shortname;
    dev->function.descriptors = fs_printer_function;
    dev->function.hs_descriptors = hs_printer_function;
    dev->function.bind = printer_func_bind;
    dev->function.setup = printer_func_setup;
    dev->function.unbind = printer_func_unbind;
    dev->function.set_alt = printer_func_set_alt;
    dev->function.disable = printer_func_disable;

    status = usb_add_function(c, &dev->function);
    if (status)
        return status;

    /* Setup the sysfs files for the printer gadget. */
    dev->pdev = device_create(usb_gadget_class, NULL, g_printer_devno,
                  NULL, "g_printer");
    if (IS_ERR(dev->pdev)) {
        ERROR(dev, "Failed to create device: g_printer\n");
        goto fail;
    }

    /*
     * Register a character device as an interface to a user mode
     * program that handles the printer specific functionality.
     */
    cdev_init(&dev->printer_cdev, &printer_io_operations);
    dev->printer_cdev.owner = THIS_MODULE;
    status = cdev_add(&dev->printer_cdev, g_printer_devno, 1);
    if (status) {
        ERROR(dev, "Failed to open char device\n");
        goto fail;
    }

    if (iPNPstring)
        strlcpy(&pnp_string[2], iPNPstring, (sizeof pnp_string)-2);

    len = strlen(pnp_string);
    pnp_string[0] = (len >> 8) & 0xFF;
    pnp_string[1] = len & 0xFF;

    usb_gadget_set_selfpowered(gadget);

    if (gadget->is_otg) {
        otg_descriptor.bmAttributes |= USB_OTG_HNP;
        printer_cfg_driver.descriptors = otg_desc;
        printer_cfg_driver.bmAttributes |= USB_CONFIG_ATT_WAKEUP;
    }

    spin_lock_init(&dev->lock);
    mutex_init(&dev->lock_printer_io);
    INIT_LIST_HEAD(&dev->tx_reqs);
    INIT_LIST_HEAD(&dev->tx_reqs_active);
    INIT_LIST_HEAD(&dev->rx_reqs);
    INIT_LIST_HEAD(&dev->rx_reqs_active);
    INIT_LIST_HEAD(&dev->rx_buffers);
    init_waitqueue_head(&dev->rx_wait);
    init_waitqueue_head(&dev->tx_wait);
    init_waitqueue_head(&dev->tx_flush_wait);

    dev->interface = -1;
    dev->printer_cdev_open = 0;
    dev->printer_status = PRINTER_NOT_ERROR;
    dev->current_rx_req = NULL;
    dev->current_rx_bytes = 0;
    dev->current_rx_buf = NULL;

    for (i = 0; i < QLEN; i++) {
        req = printer_req_alloc(dev->in_ep, USB_BUFSIZE, GFP_KERNEL);
        if (!req) {
            while (!list_empty(&dev->tx_reqs)) {
                req = container_of(dev->tx_reqs.next,
                        struct usb_request, list);
                list_del(&req->list);
                printer_req_free(dev->in_ep, req);
            }
            return -ENOMEM;
        }
        list_add(&req->list, &dev->tx_reqs);
    }

    for (i = 0; i < QLEN; i++) {
        req = printer_req_alloc(dev->out_ep, USB_BUFSIZE, GFP_KERNEL);
        if (!req) {
            while (!list_empty(&dev->rx_reqs)) {
                req = container_of(dev->rx_reqs.next,
                        struct usb_request, list);
                list_del(&req->list);
                printer_req_free(dev->out_ep, req);
            }
            return -ENOMEM;
        }
        list_add(&req->list, &dev->rx_reqs);
    }

    /* finish hookup to lower layer ... */
    dev->gadget = gadget;

    INFO(dev, "%s, version: " DRIVER_VERSION "\n", driver_desc);
    return 0;

fail:
    printer_cfg_unbind(c);
    return status;
}

static int printer_unbind(struct usb_composite_dev *cdev)
{
    return 0;
}

static int __init printer_bind(struct usb_composite_dev *cdev)
{
    int ret;

    ret = usb_string_ids_tab(cdev, strings);
    if (ret < 0)
        return ret;
    device_desc.iManufacturer = strings[USB_GADGET_MANUFACTURER_IDX].id;
    device_desc.iProduct = strings[USB_GADGET_PRODUCT_IDX].id;
    device_desc.iSerialNumber = strings[USB_GADGET_SERIAL_IDX].id;

    ret = usb_add_config(cdev, &printer_cfg_driver, printer_bind_config);
    if (ret)
        return ret;
    usb_composite_overwrite_options(cdev, &coverwrite);
    return ret;
}

static __refdata struct usb_composite_driver printer_driver = {
    .name           = shortname,
    .dev            = &device_desc,
    .strings        = dev_strings,
    .max_speed      = USB_SPEED_HIGH,
    .bind       = printer_bind,
    .unbind     = printer_unbind,
};

static int __init
init(void)
{
    int status;

    usb_gadget_class = class_create(THIS_MODULE, "usb_printer_gadget");
    if (IS_ERR(usb_gadget_class)) {
        status = PTR_ERR(usb_gadget_class);
        pr_err("unable to create usb_gadget class %d\n", status);
        return status;
    }

    status = alloc_chrdev_region(&g_printer_devno, 0, 1,
            "USB printer gadget");
    if (status) {
        pr_err("alloc_chrdev_region %d\n", status);
        class_destroy(usb_gadget_class);
        return status;
    }

    status = usb_composite_probe(&printer_driver);
    if (status) {
        class_destroy(usb_gadget_class);
        unregister_chrdev_region(g_printer_devno, 1);
        pr_err("usb_gadget_probe_driver %x\n", status);
    }

    return status;
}
module_init(init);

static void __exit
cleanup(void)
{
    mutex_lock(&usb_printer_gadget.lock_printer_io);
    usb_composite_unregister(&printer_driver);
    unregister_chrdev_region(g_printer_devno, 1);
    class_destroy(usb_gadget_class);
    mutex_unlock(&usb_printer_gadget.lock_printer_io);
}
module_exit(cleanup);

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_AUTHOR("Craig Nadler");
MODULE_LICENSE("GPL");