/*
 * Driver for USB Mass Storage compliant devices
 *
 * Current development and maintenance by:
 *   (c) 1999-2003 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
 *
 * Developed with the assistance of:
 *   (c) 2000 David L. Brown, Jr. (usb-storage@davidb.org)
 *   (c) 2003-2009 Alan Stern (stern@rowland.harvard.edu)
 *
 * Initial work by:
 *   (c) 1999 Michael Gee (michael@linuxspecific.com)
 *
 * usb_device_id support by Adam J. Richter (adam@yggdrasil.com):
 *   (c) 2000 Yggdrasil Computing, Inc.
 *
 * This driver is based on the 'USB Mass Storage Class' document. This
 * describes in detail the protocol used to communicate with such
 * devices.  Clearly, the designers had SCSI and ATAPI commands in
 * mind when they created this document.  The commands are all very
 * similar to commands in the SCSI-II and ATAPI specifications.
 *
 * It is important to note that in a number of cases this class
 * exhibits class-specific exemptions from the USB specification.
 * Notably the usage of NAK, STALL and ACK differs from the norm, in
 * that they are used to communicate wait, failed and OK on commands.
 *
 * Also, for certain devices, the interrupt endpoint is used to convey
 * status of a command.
 *
 * Please see http://www.one-eyed-alien.net/~mdharm/linux-usb for more
 * information about this driver.
 *
 * 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, 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.,
 * 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#ifdef CONFIG_USB_STORAGE_DEBUG
#define DEBUG
#endif

#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/utsname.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>

#include "usb.h"
#include "scsiglue.h"
#include "transport.h"
#include "protocol.h"
#include "debug.h"
#include "initializers.h"

#include "sierra_ms.h"
#include "option_ms.h"

#if IS_ENABLED(CONFIG_USB_UAS)
#include "uas-detect.h"
#endif

#define DRV_NAME "usb-storage"

/* Some informational data */
MODULE_AUTHOR("Matthew Dharm <mdharm-usb@one-eyed-alien.net>");
MODULE_DESCRIPTION("USB Mass Storage driver for Linux");
MODULE_LICENSE("GPL");

static unsigned int delay_use = 1;
module_param(delay_use, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(delay_use, "seconds to delay before using a new device");

static char quirks[128];
module_param_string(quirks, quirks, sizeof(quirks), S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(quirks, "supplemental list of device IDs and their quirks");


/*
 * The entries in this table correspond, line for line,
 * with the entries in usb_storage_usb_ids[], defined in usual-tables.c.
 */

/*
 *The vendor name should be kept at eight characters or less, and
 * the product name should be kept at 16 characters or less. If a device
 * has the US_FL_FIX_INQUIRY flag, then the vendor and product names
 * normally generated by a device through the INQUIRY response will be
 * taken from this list, and this is the reason for the above size
 * restriction. However, if the flag is not present, then you
 * are free to use as many characters as you like.
 */

#define UNUSUAL_DEV(idVendor, idProduct, bcdDeviceMin, bcdDeviceMax, \
                    vendor_name, product_name, use_protocol, use_transport, \
                    init_function, Flags) \
{ \
        .vendorName = vendor_name,      \
        .productName = product_name,    \
        .useProtocol = use_protocol,    \
        .useTransport = use_transport,  \
        .initFunction = init_function,  \
}

#define COMPLIANT_DEV   UNUSUAL_DEV

#define USUAL_DEV(use_protocol, use_transport) \
{ \
        .useProtocol = use_protocol,    \
        .useTransport = use_transport,  \
}

#define UNUSUAL_VENDOR_INTF(idVendor, cl, sc, pr, \
                vendor_name, product_name, use_protocol, use_transport, \
                init_function, Flags) \
{ \
        .vendorName = vendor_name,      \
        .productName = product_name,    \
        .useProtocol = use_protocol,    \
        .useTransport = use_transport,  \
        .initFunction = init_function,  \
}

static struct us_unusual_dev us_unusual_dev_list[] = {
#       include "unusual_devs.h"
        { }             /* Terminating entry */
};

static struct us_unusual_dev for_dynamic_ids =
                USUAL_DEV(USB_SC_SCSI, USB_PR_BULK);

#undef UNUSUAL_DEV
#undef COMPLIANT_DEV
#undef USUAL_DEV
#undef UNUSUAL_VENDOR_INTF

#ifdef CONFIG_LOCKDEP

static struct lock_class_key us_interface_key[USB_MAXINTERFACES];

static void us_set_lock_class(struct mutex *mutex,
                struct usb_interface *intf)
{
        struct usb_device *udev = interface_to_usbdev(intf);
        struct usb_host_config *config = udev->actconfig;
        int i;

        for (i = 0; i < config->desc.bNumInterfaces; i++) {
                if (config->interface[i] == intf)
                        break;
        }

        BUG_ON(i == config->desc.bNumInterfaces);

        lockdep_set_class(mutex, &us_interface_key[i]);
}

#else

static void us_set_lock_class(struct mutex *mutex,
                struct usb_interface *intf)
{
}

#endif

#ifdef CONFIG_PM        /* Minimal support for suspend and resume */

int usb_stor_suspend(struct usb_interface *iface, pm_message_t message)
{
        struct us_data *us = usb_get_intfdata(iface);

        /* Wait until no command is running */
        mutex_lock(&us->dev_mutex);

        if (us->suspend_resume_hook)
                (us->suspend_resume_hook)(us, US_SUSPEND);

        /*
         * When runtime PM is working, we'll set a flag to indicate
         * whether we should autoresume when a SCSI request arrives.
         */

        mutex_unlock(&us->dev_mutex);
        return 0;
}
EXPORT_SYMBOL_GPL(usb_stor_suspend);

int usb_stor_resume(struct usb_interface *iface)
{
        struct us_data *us = usb_get_intfdata(iface);

        mutex_lock(&us->dev_mutex);

        if (us->suspend_resume_hook)
                (us->suspend_resume_hook)(us, US_RESUME);

        mutex_unlock(&us->dev_mutex);
        return 0;
}
EXPORT_SYMBOL_GPL(usb_stor_resume);

int usb_stor_reset_resume(struct usb_interface *iface)
{
        struct us_data *us = usb_get_intfdata(iface);

        /* Report the reset to the SCSI core */
        usb_stor_report_bus_reset(us);

        /*
         * FIXME: Notify the subdrivers that they need to reinitialize
         * the device
         */
        return 0;
}
EXPORT_SYMBOL_GPL(usb_stor_reset_resume);

#endif /* CONFIG_PM */

/*
 * The next two routines get called just before and just after
 * a USB port reset, whether from this driver or a different one.
 */

int usb_stor_pre_reset(struct usb_interface *iface)
{
        struct us_data *us = usb_get_intfdata(iface);

        /* Make sure no command runs during the reset */
        mutex_lock(&us->dev_mutex);
        return 0;
}
EXPORT_SYMBOL_GPL(usb_stor_pre_reset);

int usb_stor_post_reset(struct usb_interface *iface)
{
        struct us_data *us = usb_get_intfdata(iface);

        /* Report the reset to the SCSI core */
        usb_stor_report_bus_reset(us);

        /*
         * FIXME: Notify the subdrivers that they need to reinitialize
         * the device
         */

        mutex_unlock(&us->dev_mutex);
        return 0;
}
EXPORT_SYMBOL_GPL(usb_stor_post_reset);

/*
 * fill_inquiry_response takes an unsigned char array (which must
 * be at least 36 characters) and populates the vendor name,
 * product name, and revision fields. Then the array is copied
 * into the SCSI command's response buffer (oddly enough
 * called request_buffer). data_len contains the length of the
 * data array, which again must be at least 36.
 */

void fill_inquiry_response(struct us_data *us, unsigned char *data,
                unsigned int data_len)
{
        if (data_len < 36) /* You lose. */
                return;

        memset(data+8, ' ', 28);
        if (data[0]&0x20) { /*
                             * USB device currently not connected. Return
                             * peripheral qualifier 001b ("...however, the
                             * physical device is not currently connected
                             * to this logical unit") and leave vendor and
                             * product identification empty. ("If the target
                             * does store some of the INQUIRY data on the
                             * device, it may return zeros or ASCII spaces
                             * (20h) in those fields until the data is
                             * available from the device.").
                             */
        } else {
                u16 bcdDevice = le16_to_cpu(us->pusb_dev->descriptor.bcdDevice);
                int n;

                n = strlen(us->unusual_dev->vendorName);
                memcpy(data+8, us->unusual_dev->vendorName, min(8, n));
                n = strlen(us->unusual_dev->productName);
                memcpy(data+16, us->unusual_dev->productName, min(16, n));

                data[32] = 0x30 + ((bcdDevice>>12) & 0x0F);
                data[33] = 0x30 + ((bcdDevice>>8) & 0x0F);
                data[34] = 0x30 + ((bcdDevice>>4) & 0x0F);
                data[35] = 0x30 + ((bcdDevice) & 0x0F);
        }

        usb_stor_set_xfer_buf(data, data_len, us->srb);
}
EXPORT_SYMBOL_GPL(fill_inquiry_response);

static int usb_stor_control_thread(void * __us)
{
        struct us_data *us = (struct us_data *)__us;
        struct Scsi_Host *host = us_to_host(us);

        for (;;) {
                usb_stor_dbg(us, "*** thread sleeping\n");
                if (wait_for_completion_interruptible(&us->cmnd_ready))
                        break;

                usb_stor_dbg(us, "*** thread awakened\n");

                /* lock the device pointers */
                mutex_lock(&(us->dev_mutex));

                /* lock access to the state */
                scsi_lock(host);

                /* When we are called with no command pending, we're done */
                if (us->srb == NULL) {
                        scsi_unlock(host);
                        mutex_unlock(&us->dev_mutex);
                        usb_stor_dbg(us, "-- exiting\n");
                        break;
                }

                /* has the command timed out *already* ? */
                if (test_bit(US_FLIDX_TIMED_OUT, &us->dflags)) {
                        us->srb->result = DID_ABORT << 16;
                        goto SkipForAbort;
                }

                scsi_unlock(host);

                /*
                 * reject the command if the direction indicator
                 * is UNKNOWN
                 */
                if (us->srb->sc_data_direction == DMA_BIDIRECTIONAL) {
                        usb_stor_dbg(us, "UNKNOWN data direction\n");
                        us->srb->result = DID_ERROR << 16;
                }

                /*
                 * reject if target != 0 or if LUN is higher than
                 * the maximum known LUN
                 */
                else if (us->srb->device->id &&
                                !(us->fflags & US_FL_SCM_MULT_TARG)) {
                        usb_stor_dbg(us, "Bad target number (%d:%llu)\n",
                                     us->srb->device->id,
                                     us->srb->device->lun);
                        us->srb->result = DID_BAD_TARGET << 16;
                }

                else if (us->srb->device->lun > us->max_lun) {
                        usb_stor_dbg(us, "Bad LUN (%d:%llu)\n",
                                     us->srb->device->id,
                                     us->srb->device->lun);
                        us->srb->result = DID_BAD_TARGET << 16;
                }

                /*
                 * Handle those devices which need us to fake
                 * their inquiry data
                 */
                else if ((us->srb->cmnd[0] == INQUIRY) &&
                            (us->fflags & US_FL_FIX_INQUIRY)) {
                        unsigned char data_ptr[36] = {
                            0x00, 0x80, 0x02, 0x02,
                            0x1F, 0x00, 0x00, 0x00};

                        usb_stor_dbg(us, "Faking INQUIRY command\n");
                        fill_inquiry_response(us, data_ptr, 36);
                        us->srb->result = SAM_STAT_GOOD;
                }

                /* we've got a command, let's do it! */
                else {
                        US_DEBUG(usb_stor_show_command(us, us->srb));
                        us->proto_handler(us->srb, us);
                        usb_mark_last_busy(us->pusb_dev);
                }

                /* lock access to the state */
                scsi_lock(host);

                /* indicate that the command is done */
                if (us->srb->result != DID_ABORT << 16) {
                        usb_stor_dbg(us, "scsi cmd done, result=0x%x\n",
                                     us->srb->result);
                        us->srb->scsi_done(us->srb);
                } else {
SkipForAbort:
                        usb_stor_dbg(us, "scsi command aborted\n");
                }

                /*
                 * If an abort request was received we need to signal that
                 * the abort has finished.  The proper test for this is
                 * the TIMED_OUT flag, not srb->result == DID_ABORT, because
                 * the timeout might have occurred after the command had
                 * already completed with a different result code.
                 */
                if (test_bit(US_FLIDX_TIMED_OUT, &us->dflags)) {
                        complete(&(us->notify));

                        /* Allow USB transfers to resume */
                        clear_bit(US_FLIDX_ABORTING, &us->dflags);
                        clear_bit(US_FLIDX_TIMED_OUT, &us->dflags);
                }

                /* finished working on this command */
                us->srb = NULL;
                scsi_unlock(host);

                /* unlock the device pointers */
                mutex_unlock(&us->dev_mutex);
        } /* for (;;) */

        /* Wait until we are told to stop */
        for (;;) {
                set_current_state(TASK_INTERRUPTIBLE);
                if (kthread_should_stop())
                        break;
                schedule();
        }
        __set_current_state(TASK_RUNNING);
        return 0;
}

/***********************************************************************
 * Device probing and disconnecting
 ***********************************************************************/

/* Associate our private data with the USB device */
static int associate_dev(struct us_data *us, struct usb_interface *intf)
{
        /* Fill in the device-related fields */
        us->pusb_dev = interface_to_usbdev(intf);
        us->pusb_intf = intf;
        us->ifnum = intf->cur_altsetting->desc.bInterfaceNumber;
        usb_stor_dbg(us, "Vendor: 0x%04x, Product: 0x%04x, Revision: 0x%04x\n",
                     le16_to_cpu(us->pusb_dev->descriptor.idVendor),
                     le16_to_cpu(us->pusb_dev->descriptor.idProduct),
                     le16_to_cpu(us->pusb_dev->descriptor.bcdDevice));
        usb_stor_dbg(us, "Interface Subclass: 0x%02x, Protocol: 0x%02x\n",
                     intf->cur_altsetting->desc.bInterfaceSubClass,
                     intf->cur_altsetting->desc.bInterfaceProtocol);

        /* Store our private data in the interface */
        usb_set_intfdata(intf, us);

        /* Allocate the control/setup and DMA-mapped buffers */
        us->cr = kmalloc(sizeof(*us->cr), GFP_KERNEL);
        if (!us->cr)
                return -ENOMEM;

        us->iobuf = usb_alloc_coherent(us->pusb_dev, US_IOBUF_SIZE,
                        GFP_KERNEL, &us->iobuf_dma);
        if (!us->iobuf) {
                usb_stor_dbg(us, "I/O buffer allocation failed\n");
                return -ENOMEM;
        }
        return 0;
}

/* Works only for digits and letters, but small and fast */
#define TOLOWER(x) ((x) | 0x20)

/* Adjust device flags based on the "quirks=" module parameter */
void usb_stor_adjust_quirks(struct usb_device *udev, unsigned long *fflags)
{
        char *p;
        u16 vid = le16_to_cpu(udev->descriptor.idVendor);
        u16 pid = le16_to_cpu(udev->descriptor.idProduct);
        unsigned f = 0;
        unsigned int mask = (US_FL_SANE_SENSE | US_FL_BAD_SENSE |
                        US_FL_FIX_CAPACITY | US_FL_IGNORE_UAS |
                        US_FL_CAPACITY_HEURISTICS | US_FL_IGNORE_DEVICE |
                        US_FL_NOT_LOCKABLE | US_FL_MAX_SECTORS_64 |
                        US_FL_CAPACITY_OK | US_FL_IGNORE_RESIDUE |
                        US_FL_SINGLE_LUN | US_FL_NO_WP_DETECT |
                        US_FL_NO_READ_DISC_INFO | US_FL_NO_READ_CAPACITY_16 |
                        US_FL_INITIAL_READ10 | US_FL_WRITE_CACHE |
                        US_FL_NO_ATA_1X | US_FL_NO_REPORT_OPCODES |
                        US_FL_MAX_SECTORS_240 | US_FL_NO_REPORT_LUNS |
                        US_FL_ALWAYS_SYNC);

        p = quirks;
        while (*p) {
                /* Each entry consists of VID:PID:flags */
                if (vid == simple_strtoul(p, &p, 16) &&
                                *p == ':' &&
                                pid == simple_strtoul(p+1, &p, 16) &&
                                *p == ':')
                        break;

                /* Move forward to the next entry */
                while (*p) {
                        if (*p++ == ',')
                                break;
                }
        }
        if (!*p)        /* No match */
                return;

        /* Collect the flags */
        while (*++p && *p != ',') {
                switch (TOLOWER(*p)) {
                case 'a':
                        f |= US_FL_SANE_SENSE;
                        break;
                case 'b':
                        f |= US_FL_BAD_SENSE;
                        break;
                case 'c':
                        f |= US_FL_FIX_CAPACITY;
                        break;
                case 'd':
                        f |= US_FL_NO_READ_DISC_INFO;
                        break;
                case 'e':
                        f |= US_FL_NO_READ_CAPACITY_16;
                        break;
                case 'f':
                        f |= US_FL_NO_REPORT_OPCODES;
                        break;
                case 'g':
                        f |= US_FL_MAX_SECTORS_240;
                        break;
                case 'h':
                        f |= US_FL_CAPACITY_HEURISTICS;
                        break;
                case 'i':
                        f |= US_FL_IGNORE_DEVICE;
                        break;
                case 'j':
                        f |= US_FL_NO_REPORT_LUNS;
                        break;
                case 'l':
                        f |= US_FL_NOT_LOCKABLE;
                        break;
                case 'm':
                        f |= US_FL_MAX_SECTORS_64;
                        break;
                case 'n':
                        f |= US_FL_INITIAL_READ10;
                        break;
                case 'o':
                        f |= US_FL_CAPACITY_OK;
                        break;
                case 'p':
                        f |= US_FL_WRITE_CACHE;
                        break;
                case 'r':
                        f |= US_FL_IGNORE_RESIDUE;
                        break;
                case 's':
                        f |= US_FL_SINGLE_LUN;
                        break;
                case 't':
                        f |= US_FL_NO_ATA_1X;
                        break;
                case 'u':
                        f |= US_FL_IGNORE_UAS;
                        break;
                case 'w':
                        f |= US_FL_NO_WP_DETECT;
                        break;
                case 'y':
                        f |= US_FL_ALWAYS_SYNC;
                        break;
                /* Ignore unrecognized flag characters */
                }
        }
        *fflags = (*fflags & ~mask) | f;
}
EXPORT_SYMBOL_GPL(usb_stor_adjust_quirks);

/* Get the unusual_devs entries and the string descriptors */
static int get_device_info(struct us_data *us, const struct usb_device_id *id,
                struct us_unusual_dev *unusual_dev)
{
        struct usb_device *dev = us->pusb_dev;
        struct usb_interface_descriptor *idesc =
                &us->pusb_intf->cur_altsetting->desc;
        struct device *pdev = &us->pusb_intf->dev;

        /* Store the entries */
        us->unusual_dev = unusual_dev;
        us->subclass = (unusual_dev->useProtocol == USB_SC_DEVICE) ?
                        idesc->bInterfaceSubClass :
                        unusual_dev->useProtocol;
        us->protocol = (unusual_dev->useTransport == USB_PR_DEVICE) ?
                        idesc->bInterfaceProtocol :
                        unusual_dev->useTransport;
        us->fflags = id->driver_info;
        usb_stor_adjust_quirks(us->pusb_dev, &us->fflags);

        if (us->fflags & US_FL_IGNORE_DEVICE) {
                dev_info(pdev, "device ignored\n");
                return -ENODEV;
        }

        /*
         * This flag is only needed when we're in high-speed, so let's
         * disable it if we're in full-speed
         */
        if (dev->speed != USB_SPEED_HIGH)
                us->fflags &= ~US_FL_GO_SLOW;

        if (us->fflags)
                dev_info(pdev, "Quirks match for vid %04x pid %04x: %lx\n",
                                le16_to_cpu(dev->descriptor.idVendor),
                                le16_to_cpu(dev->descriptor.idProduct),
                                us->fflags);

        /*
         * Log a message if a non-generic unusual_dev entry contains an
         * unnecessary subclass or protocol override.  This may stimulate
         * reports from users that will help us remove unneeded entries
         * from the unusual_devs.h table.
         */
        if (id->idVendor || id->idProduct) {
                static const char *msgs[3] = {
                        "an unneeded SubClass entry",
                        "an unneeded Protocol entry",
                        "unneeded SubClass and Protocol entries"};
                struct usb_device_descriptor *ddesc = &dev->descriptor;
                int msg = -1;

                if (unusual_dev->useProtocol != USB_SC_DEVICE &&
                        us->subclass == idesc->bInterfaceSubClass)
                        msg += 1;
                if (unusual_dev->useTransport != USB_PR_DEVICE &&
                        us->protocol == idesc->bInterfaceProtocol)
                        msg += 2;
                if (msg >= 0 && !(us->fflags & US_FL_NEED_OVERRIDE))
                        dev_notice(pdev, "This device "
                                        "(%04x,%04x,%04x S %02x P %02x)"
                                        " has %s in unusual_devs.h (kernel"
                                        " %s)\n"
                                        "   Please send a copy of this message to "
                                        "<linux-usb@vger.kernel.org> and "
                                        "<usb-storage@lists.one-eyed-alien.net>\n",
                                        le16_to_cpu(ddesc->idVendor),
                                        le16_to_cpu(ddesc->idProduct),
                                        le16_to_cpu(ddesc->bcdDevice),
                                        idesc->bInterfaceSubClass,
                                        idesc->bInterfaceProtocol,
                                        msgs[msg],
                                        utsname()->release);
        }

        return 0;
}

/* Get the transport settings */
static void get_transport(struct us_data *us)
{
        switch (us->protocol) {
        case USB_PR_CB:
                us->transport_name = "Control/Bulk";
                us->transport = usb_stor_CB_transport;
                us->transport_reset = usb_stor_CB_reset;
                us->max_lun = 7;
                break;

        case USB_PR_CBI:
                us->transport_name = "Control/Bulk/Interrupt";
                us->transport = usb_stor_CB_transport;
                us->transport_reset = usb_stor_CB_reset;
                us->max_lun = 7;
                break;

        case USB_PR_BULK:
                us->transport_name = "Bulk";
                us->transport = usb_stor_Bulk_transport;
                us->transport_reset = usb_stor_Bulk_reset;
                break;
        }
}

/* Get the protocol settings */
static void get_protocol(struct us_data *us)
{
        switch (us->subclass) {
        case USB_SC_RBC:
                us->protocol_name = "Reduced Block Commands (RBC)";
                us->proto_handler = usb_stor_transparent_scsi_command;
                break;

        case USB_SC_8020:
                us->protocol_name = "8020i";
                us->proto_handler = usb_stor_pad12_command;
                us->max_lun = 0;
                break;

        case USB_SC_QIC:
                us->protocol_name = "QIC-157";
                us->proto_handler = usb_stor_pad12_command;
                us->max_lun = 0;
                break;

        case USB_SC_8070:
                us->protocol_name = "8070i";
                us->proto_handler = usb_stor_pad12_command;
                us->max_lun = 0;
                break;

        case USB_SC_SCSI:
                us->protocol_name = "Transparent SCSI";
                us->proto_handler = usb_stor_transparent_scsi_command;
                break;

        case USB_SC_UFI:
                us->protocol_name = "Uniform Floppy Interface (UFI)";
                us->proto_handler = usb_stor_ufi_command;
                break;
        }
}

/* Get the pipe settings */
static int get_pipes(struct us_data *us)
{
        struct usb_host_interface *altsetting =
                us->pusb_intf->cur_altsetting;
        int i;
        struct usb_endpoint_descriptor *ep;
        struct usb_endpoint_descriptor *ep_in = NULL;
        struct usb_endpoint_descriptor *ep_out = NULL;
        struct usb_endpoint_descriptor *ep_int = NULL;

        /*
         * Find the first endpoint of each type we need.
         * We are expecting a minimum of 2 endpoints - in and out (bulk).
         * An optional interrupt-in is OK (necessary for CBI protocol).
         * We will ignore any others.
         */
        for (i = 0; i < altsetting->desc.bNumEndpoints; i++) {
                ep = &altsetting->endpoint[i].desc;

                if (usb_endpoint_xfer_bulk(ep)) {
                        if (usb_endpoint_dir_in(ep)) {
                                if (!ep_in)
                                        ep_in = ep;
                        } else {
                                if (!ep_out)
                                        ep_out = ep;
                        }
                }

                else if (usb_endpoint_is_int_in(ep)) {
                        if (!ep_int)
                                ep_int = ep;
                }
        }

        if (!ep_in || !ep_out || (us->protocol == USB_PR_CBI && !ep_int)) {
                usb_stor_dbg(us, "Endpoint sanity check failed! Rejecting dev.\n");
                return -EIO;
        }

        /* Calculate and store the pipe values */
        us->send_ctrl_pipe = usb_sndctrlpipe(us->pusb_dev, 0);
        us->recv_ctrl_pipe = usb_rcvctrlpipe(us->pusb_dev, 0);
        us->send_bulk_pipe = usb_sndbulkpipe(us->pusb_dev,
                usb_endpoint_num(ep_out));
        us->recv_bulk_pipe = usb_rcvbulkpipe(us->pusb_dev,
                usb_endpoint_num(ep_in));
        if (ep_int) {
                us->recv_intr_pipe = usb_rcvintpipe(us->pusb_dev,
                        usb_endpoint_num(ep_int));
                us->ep_bInterval = ep_int->bInterval;
        }
        return 0;
}

/* Initialize all the dynamic resources we need */
static int usb_stor_acquire_resources(struct us_data *us)
{
        int p;
        struct task_struct *th;

        us->current_urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!us->current_urb)
                return -ENOMEM;

        /*
         * Just before we start our control thread, initialize
         * the device if it needs initialization
         */
        if (us->unusual_dev->initFunction) {
                p = us->unusual_dev->initFunction(us);
                if (p)
                        return p;
        }

        /* Start up our control thread */
        th = kthread_run(usb_stor_control_thread, us, "usb-storage");
        if (IS_ERR(th)) {
                dev_warn(&us->pusb_intf->dev,
                                "Unable to start control thread\n");
                return PTR_ERR(th);
        }
        us->ctl_thread = th;

        return 0;
}

/* Release all our dynamic resources */
static void usb_stor_release_resources(struct us_data *us)
{
        /*
         * Tell the control thread to exit.  The SCSI host must
         * already have been removed and the DISCONNECTING flag set
         * so that we won't accept any more commands.
         */
        usb_stor_dbg(us, "-- sending exit command to thread\n");
        complete(&us->cmnd_ready);
        if (us->ctl_thread)
                kthread_stop(us->ctl_thread);

        /* Call the destructor routine, if it exists */
        if (us->extra_destructor) {
                usb_stor_dbg(us, "-- calling extra_destructor()\n");
                us->extra_destructor(us->extra);
        }

        /* Free the extra data and the URB */
        kfree(us->extra);
        usb_free_urb(us->current_urb);
}

/* Dissociate from the USB device */
static void dissociate_dev(struct us_data *us)
{
        /* Free the buffers */
        kfree(us->cr);
        usb_free_coherent(us->pusb_dev, US_IOBUF_SIZE, us->iobuf, us->iobuf_dma);

        /* Remove our private data from the interface */
        usb_set_intfdata(us->pusb_intf, NULL);
}

/*
 * First stage of disconnect processing: stop SCSI scanning,
 * remove the host, and stop accepting new commands
 */
static void quiesce_and_remove_host(struct us_data *us)
{
        struct Scsi_Host *host = us_to_host(us);

        /* If the device is really gone, cut short reset delays */
        if (us->pusb_dev->state == USB_STATE_NOTATTACHED) {
                set_bit(US_FLIDX_DISCONNECTING, &us->dflags);
                wake_up(&us->delay_wait);
        }

        /*
         * Prevent SCSI scanning (if it hasn't started yet)
         * or wait for the SCSI-scanning routine to stop.
         */
        cancel_delayed_work_sync(&us->scan_dwork);

        /* Balance autopm calls if scanning was cancelled */
        if (test_bit(US_FLIDX_SCAN_PENDING, &us->dflags))
                usb_autopm_put_interface_no_suspend(us->pusb_intf);

        /*
         * Removing the host will perform an orderly shutdown: caches
         * synchronized, disks spun down, etc.
         */
        scsi_remove_host(host);

        /*
         * Prevent any new commands from being accepted and cut short
         * reset delays.
         */
        scsi_lock(host);
        set_bit(US_FLIDX_DISCONNECTING, &us->dflags);
        scsi_unlock(host);
        wake_up(&us->delay_wait);
}

/* Second stage of disconnect processing: deallocate all resources */
static void release_everything(struct us_data *us)
{
        usb_stor_release_resources(us);
        dissociate_dev(us);

        /*
         * Drop our reference to the host; the SCSI core will free it
         * (and "us" along with it) when the refcount becomes 0.
         */
        scsi_host_put(us_to_host(us));
}

/* Delayed-work routine to carry out SCSI-device scanning */
static void usb_stor_scan_dwork(struct work_struct *work)
{
        struct us_data *us = container_of(work, struct us_data,
                        scan_dwork.work);
        struct device *dev = &us->pusb_intf->dev;

        dev_dbg(dev, "starting scan\n");

        /* For bulk-only devices, determine the max LUN value */
        if (us->protocol == USB_PR_BULK &&
            !(us->fflags & US_FL_SINGLE_LUN) &&
            !(us->fflags & US_FL_SCM_MULT_TARG)) {
                mutex_lock(&us->dev_mutex);
                us->max_lun = usb_stor_Bulk_max_lun(us);
                /*
                 * Allow proper scanning of devices that present more than 8 LUNs
                 * While not affecting other devices that may need the previous
                 * behavior
                 */
                if (us->max_lun >= 8)
                        us_to_host(us)->max_lun = us->max_lun+1;
                mutex_unlock(&us->dev_mutex);
        }
        scsi_scan_host(us_to_host(us));
        dev_dbg(dev, "scan complete\n");

        /* Should we unbind if no devices were detected? */

        usb_autopm_put_interface(us->pusb_intf);
        clear_bit(US_FLIDX_SCAN_PENDING, &us->dflags);
}

static unsigned int usb_stor_sg_tablesize(struct usb_interface *intf)
{
        struct usb_device *usb_dev = interface_to_usbdev(intf);

        if (usb_dev->bus->sg_tablesize) {
                return usb_dev->bus->sg_tablesize;
        }
        return SG_ALL;
}

/* First part of general USB mass-storage probing */
int usb_stor_probe1(struct us_data **pus,
                struct usb_interface *intf,
                const struct usb_device_id *id,
                struct us_unusual_dev *unusual_dev,
                struct scsi_host_template *sht)
{
        struct Scsi_Host *host;
        struct us_data *us;
        int result;

        dev_info(&intf->dev, "USB Mass Storage device detected\n");

        /*
         * Ask the SCSI layer to allocate a host structure, with extra
         * space at the end for our private us_data structure.
         */
        host = scsi_host_alloc(sht, sizeof(*us));
        if (!host) {
                dev_warn(&intf->dev, "Unable to allocate the scsi host\n");
                return -ENOMEM;
        }

        /*
         * Allow 16-byte CDBs and thus > 2TB
         */
        host->max_cmd_len = 16;
        host->sg_tablesize = usb_stor_sg_tablesize(intf);
        *pus = us = host_to_us(host);
        mutex_init(&(us->dev_mutex));
        us_set_lock_class(&us->dev_mutex, intf);
        init_completion(&us->cmnd_ready);
        init_completion(&(us->notify));
        init_waitqueue_head(&us->delay_wait);
        INIT_DELAYED_WORK(&us->scan_dwork, usb_stor_scan_dwork);

        /* Associate the us_data structure with the USB device */
        result = associate_dev(us, intf);
        if (result)
                goto BadDevice;

        /* Get the unusual_devs entries and the descriptors */
        result = get_device_info(us, id, unusual_dev);
        if (result)
                goto BadDevice;

        /* Get standard transport and protocol settings */
        get_transport(us);
        get_protocol(us);

        /*
         * Give the caller a chance to fill in specialized transport
         * or protocol settings.
         */
        return 0;

BadDevice:
        usb_stor_dbg(us, "storage_probe() failed\n");
        release_everything(us);
        return result;
}
EXPORT_SYMBOL_GPL(usb_stor_probe1);

/* Second part of general USB mass-storage probing */
int usb_stor_probe2(struct us_data *us)
{
        int result;
        struct device *dev = &us->pusb_intf->dev;

        /* Make sure the transport and protocol have both been set */
        if (!us->transport || !us->proto_handler) {
                result = -ENXIO;
                goto BadDevice;
        }
        usb_stor_dbg(us, "Transport: %s\n", us->transport_name);
        usb_stor_dbg(us, "Protocol: %s\n", us->protocol_name);

        if (us->fflags & US_FL_SCM_MULT_TARG) {
                /*
                 * SCM eUSCSI bridge devices can have different numbers
                 * of LUNs on different targets; allow all to be probed.
                 */
                us->max_lun = 7;
                /* The eUSCSI itself has ID 7, so avoid scanning that */
                us_to_host(us)->this_id = 7;
                /* max_id is 8 initially, so no need to set it here */
        } else {
                /* In the normal case there is only a single target */
                us_to_host(us)->max_id = 1;
                /*
                 * Like Windows, we won't store the LUN bits in CDB[1] for
                 * SCSI-2 devices using the Bulk-Only transport (even though
                 * this violates the SCSI spec).
                 */
                if (us->transport == usb_stor_Bulk_transport)
                        us_to_host(us)->no_scsi2_lun_in_cdb = 1;
        }

        /* fix for single-lun devices */
        if (us->fflags & US_FL_SINGLE_LUN)
                us->max_lun = 0;

        /* Find the endpoints and calculate pipe values */
        result = get_pipes(us);
        if (result)
                goto BadDevice;

        /*
         * If the device returns invalid data for the first READ(10)
         * command, indicate the command should be retried.
         */
        if (us->fflags & US_FL_INITIAL_READ10)
                set_bit(US_FLIDX_REDO_READ10, &us->dflags);

        /* Acquire all the other resources and add the host */
        result = usb_stor_acquire_resources(us);
        if (result)
                goto BadDevice;
        usb_autopm_get_interface_no_resume(us->pusb_intf);
        snprintf(us->scsi_name, sizeof(us->scsi_name), "usb-storage %s",
                                        dev_name(&us->pusb_intf->dev));
        result = scsi_add_host(us_to_host(us), dev);
        if (result) {
                dev_warn(dev,
                                "Unable to add the scsi host\n");
                goto HostAddErr;
        }

        /* Submit the delayed_work for SCSI-device scanning */
        set_bit(US_FLIDX_SCAN_PENDING, &us->dflags);

        if (delay_use > 0)
                dev_dbg(dev, "waiting for device to settle before scanning\n");
        queue_delayed_work(system_freezable_wq, &us->scan_dwork,
                        delay_use * HZ);
        return 0;

        /* We come here if there are any problems */
HostAddErr:
        usb_autopm_put_interface_no_suspend(us->pusb_intf);
BadDevice:
        usb_stor_dbg(us, "storage_probe() failed\n");
        release_everything(us);
        return result;
}
EXPORT_SYMBOL_GPL(usb_stor_probe2);

/* Handle a USB mass-storage disconnect */
void usb_stor_disconnect(struct usb_interface *intf)
{
        struct us_data *us = usb_get_intfdata(intf);

        quiesce_and_remove_host(us);
        release_everything(us);
}
EXPORT_SYMBOL_GPL(usb_stor_disconnect);

static struct scsi_host_template usb_stor_host_template;

/* The main probe routine for standard devices */
static int storage_probe(struct usb_interface *intf,
                         const struct usb_device_id *id)
{
        struct us_unusual_dev *unusual_dev;
        struct us_data *us;
        int result;
        int size;

        /* If uas is enabled and this device can do uas then ignore it. */
#if IS_ENABLED(CONFIG_USB_UAS)
        if (uas_use_uas_driver(intf, id, NULL))
                return -ENXIO;
#endif

        /*
         * If the device isn't standard (is handled by a subdriver
         * module) then don't accept it.
         */
        if (usb_usual_ignore_device(intf))
                return -ENXIO;

        /*
         * Call the general probe procedures.
         *
         * The unusual_dev_list array is parallel to the usb_storage_usb_ids
         * table, so we use the index of the id entry to find the
         * corresponding unusual_devs entry.
         */

        size = ARRAY_SIZE(us_unusual_dev_list);
        if (id >= usb_storage_usb_ids && id < usb_storage_usb_ids + size) {
                unusual_dev = (id - usb_storage_usb_ids) + us_unusual_dev_list;
        } else {
                unusual_dev = &for_dynamic_ids;

                dev_dbg(&intf->dev, "Use Bulk-Only transport with the Transparent SCSI protocol for dynamic id: 0x%04x 0x%04x\n",
                        id->idVendor, id->idProduct);
        }

        result = usb_stor_probe1(&us, intf, id, unusual_dev,
                                 &usb_stor_host_template);
        if (result)
                return result;

        /* No special transport or protocol settings in the main module */

        result = usb_stor_probe2(us);
        return result;
}

static struct usb_driver usb_storage_driver = {
        .name =         DRV_NAME,
        .probe =        storage_probe,
        .disconnect =   usb_stor_disconnect,
        .suspend =      usb_stor_suspend,
        .resume =       usb_stor_resume,
        .reset_resume = usb_stor_reset_resume,
        .pre_reset =    usb_stor_pre_reset,
        .post_reset =   usb_stor_post_reset,
        .id_table =     usb_storage_usb_ids,
        .supports_autosuspend = 1,
        .soft_unbind =  1,
};

module_usb_stor_driver(usb_storage_driver, usb_stor_host_template, DRV_NAME);