/*
 * Driver for USB Mass Storage compliant devices
 * SCSI layer glue code
 *
 * Current development and maintenance by:
 *   (c) 1999-2002 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
 *
 * Developed with the assistance of:
 *   (c) 2000 David L. Brown, Jr. (usb-storage@davidb.org)
 *   (c) 2000 Stephen J. Gowdy (SGowdy@lbl.gov)
 *
 * Initial work by:
 *   (c) 1999 Michael Gee (michael@linuxspecific.com)
 *
 * 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.
 */

#include <linux/module.h>
#include <linux/mutex.h>

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

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

/*
 * Vendor IDs for companies that seem to include the READ CAPACITY bug
 * in all their devices
 */
#define VENDOR_ID_NOKIA         0x0421
#define VENDOR_ID_NIKON         0x04b0
#define VENDOR_ID_PENTAX        0x0a17
#define VENDOR_ID_MOTOROLA      0x22b8

/***********************************************************************
 * Host functions 
 ***********************************************************************/

static const char* host_info(struct Scsi_Host *host)
{
        struct us_data *us = host_to_us(host);
        return us->scsi_name;
}

static int slave_alloc (struct scsi_device *sdev)
{
        struct us_data *us = host_to_us(sdev->host);

        /*
         * Set the INQUIRY transfer length to 36.  We don't use any of
         * the extra data and many devices choke if asked for more or
         * less than 36 bytes.
         */
        sdev->inquiry_len = 36;

        /*
         * USB has unusual DMA-alignment requirements: Although the
         * starting address of each scatter-gather element doesn't matter,
         * the length of each element except the last must be divisible
         * by the Bulk maxpacket value.  There's currently no way to
         * express this by block-layer constraints, so we'll cop out
         * and simply require addresses to be aligned at 512-byte
         * boundaries.  This is okay since most block I/O involves
         * hardware sectors that are multiples of 512 bytes in length,
         * and since host controllers up through USB 2.0 have maxpacket
         * values no larger than 512.
         *
         * But it doesn't suffice for Wireless USB, where Bulk maxpacket
         * values can be as large as 2048.  To make that work properly
         * will require changes to the block layer.
         */
        blk_queue_update_dma_alignment(sdev->request_queue, (512 - 1));

        /* Tell the SCSI layer if we know there is more than one LUN */
        if (us->protocol == USB_PR_BULK && us->max_lun > 0)
                sdev->sdev_bflags |= BLIST_FORCELUN;

        return 0;
}

static int slave_configure(struct scsi_device *sdev)
{
        struct us_data *us = host_to_us(sdev->host);

        /*
         * Many devices have trouble transferring more than 32KB at a time,
         * while others have trouble with more than 64K. At this time we
         * are limiting both to 32K (64 sectores).
         */
        if (us->fflags & (US_FL_MAX_SECTORS_64 | US_FL_MAX_SECTORS_MIN)) {
                unsigned int max_sectors = 64;

                if (us->fflags & US_FL_MAX_SECTORS_MIN)
                        max_sectors = PAGE_CACHE_SIZE >> 9;
                if (queue_max_hw_sectors(sdev->request_queue) > max_sectors)
                        blk_queue_max_hw_sectors(sdev->request_queue,
                                              max_sectors);
        } else if (sdev->type == TYPE_TAPE) {
                /*
                 * Tapes need much higher max_sector limits, so just
                 * raise it to the maximum possible (4 GB / 512) and
                 * let the queue segment size sort out the real limit.
                 */
                blk_queue_max_hw_sectors(sdev->request_queue, 0x7FFFFF);
        } else if (us->pusb_dev->speed >= USB_SPEED_SUPER) {
                /*
                 * USB3 devices will be limited to 2048 sectors. This gives us
                 * better throughput on most devices.
                 */
                blk_queue_max_hw_sectors(sdev->request_queue, 2048);
        }

        /*
         * Some USB host controllers can't do DMA; they have to use PIO.
         * They indicate this by setting their dma_mask to NULL.  For
         * such controllers we need to make sure the block layer sets
         * up bounce buffers in addressable memory.
         */
        if (!us->pusb_dev->bus->controller->dma_mask)
                blk_queue_bounce_limit(sdev->request_queue, BLK_BOUNCE_HIGH);

        /*
         * We can't put these settings in slave_alloc() because that gets
         * called before the device type is known.  Consequently these
         * settings can't be overridden via the scsi devinfo mechanism.
         */
        if (sdev->type == TYPE_DISK) {

                /*
                 * Some vendors seem to put the READ CAPACITY bug into
                 * all their devices -- primarily makers of cell phones
                 * and digital cameras.  Since these devices always use
                 * flash media and can be expected to have an even number
                 * of sectors, we will always enable the CAPACITY_HEURISTICS
                 * flag unless told otherwise.
                 */
                switch (le16_to_cpu(us->pusb_dev->descriptor.idVendor)) {
                case VENDOR_ID_NOKIA:
                case VENDOR_ID_NIKON:
                case VENDOR_ID_PENTAX:
                case VENDOR_ID_MOTOROLA:
                        if (!(us->fflags & (US_FL_FIX_CAPACITY |
                                        US_FL_CAPACITY_OK)))
                                us->fflags |= US_FL_CAPACITY_HEURISTICS;
                        break;
                }

                /*
                 * Disk-type devices use MODE SENSE(6) if the protocol
                 * (SubClass) is Transparent SCSI, otherwise they use
                 * MODE SENSE(10).
                 */
                if (us->subclass != USB_SC_SCSI && us->subclass != USB_SC_CYP_ATACB)
                        sdev->use_10_for_ms = 1;

                /*
                 *Many disks only accept MODE SENSE transfer lengths of
                 * 192 bytes (that's what Windows uses).
                 */
                sdev->use_192_bytes_for_3f = 1;

                /*
                 * Some devices don't like MODE SENSE with page=0x3f,
                 * which is the command used for checking if a device
                 * is write-protected.  Now that we tell the sd driver
                 * to do a 192-byte transfer with this command the
                 * majority of devices work fine, but a few still can't
                 * handle it.  The sd driver will simply assume those
                 * devices are write-enabled.
                 */
                if (us->fflags & US_FL_NO_WP_DETECT)
                        sdev->skip_ms_page_3f = 1;

                /*
                 * A number of devices have problems with MODE SENSE for
                 * page x08, so we will skip it.
                 */
                sdev->skip_ms_page_8 = 1;

                /* Some devices don't handle VPD pages correctly */
                sdev->skip_vpd_pages = 1;

                /* Do not attempt to use REPORT SUPPORTED OPERATION CODES */
                sdev->no_report_opcodes = 1;

                /* Do not attempt to use WRITE SAME */
                sdev->no_write_same = 1;

                /*
                 * Some disks return the total number of blocks in response
                 * to READ CAPACITY rather than the highest block number.
                 * If this device makes that mistake, tell the sd driver.
                 */
                if (us->fflags & US_FL_FIX_CAPACITY)
                        sdev->fix_capacity = 1;

                /*
                 * A few disks have two indistinguishable version, one of
                 * which reports the correct capacity and the other does not.
                 * The sd driver has to guess which is the case.
                 */
                if (us->fflags & US_FL_CAPACITY_HEURISTICS)
                        sdev->guess_capacity = 1;

                /* Some devices cannot handle READ_CAPACITY_16 */
                if (us->fflags & US_FL_NO_READ_CAPACITY_16)
                        sdev->no_read_capacity_16 = 1;

                /*
                 * Many devices do not respond properly to READ_CAPACITY_16.
                 * Tell the SCSI layer to try READ_CAPACITY_10 first.
                 * However some USB 3.0 drive enclosures return capacity
                 * modulo 2TB. Those must use READ_CAPACITY_16
                 */
                if (!(us->fflags & US_FL_NEEDS_CAP16))
                        sdev->try_rc_10_first = 1;

                /* assume SPC3 or latter devices support sense size > 18 */
                if (sdev->scsi_level > SCSI_SPC_2)
                        us->fflags |= US_FL_SANE_SENSE;

                /*
                 * USB-IDE bridges tend to report SK = 0x04 (Non-recoverable
                 * Hardware Error) when any low-level error occurs,
                 * recoverable or not.  Setting this flag tells the SCSI
                 * midlayer to retry such commands, which frequently will
                 * succeed and fix the error.  The worst this can lead to
                 * is an occasional series of retries that will all fail.
                 */
                sdev->retry_hwerror = 1;

                /*
                 * USB disks should allow restart.  Some drives spin down
                 * automatically, requiring a START-STOP UNIT command.
                 */
                sdev->allow_restart = 1;

                /*
                 * Some USB cardreaders have trouble reading an sdcard's last
                 * sector in a larger then 1 sector read, since the performance
                 * impact is negligible we set this flag for all USB disks
                 */
                sdev->last_sector_bug = 1;

                /*
                 * Enable last-sector hacks for single-target devices using
                 * the Bulk-only transport, unless we already know the
                 * capacity will be decremented or is correct.
                 */
                if (!(us->fflags & (US_FL_FIX_CAPACITY | US_FL_CAPACITY_OK |
                                        US_FL_SCM_MULT_TARG)) &&
                                us->protocol == USB_PR_BULK)
                        us->use_last_sector_hacks = 1;

                /* Check if write cache default on flag is set or not */
                if (us->fflags & US_FL_WRITE_CACHE)
                        sdev->wce_default_on = 1;

                /* A few buggy USB-ATA bridges don't understand FUA */
                if (us->fflags & US_FL_BROKEN_FUA)
                        sdev->broken_fua = 1;

                /* Some even totally fail to indicate a cache */
                if (us->fflags & US_FL_ALWAYS_SYNC) {
                        /* don't read caching information */
                        sdev->skip_ms_page_8 = 1;
                        sdev->skip_ms_page_3f = 1;
                        /* assume sync is needed */
                        sdev->wce_default_on = 1;
                }
        } else {

                /*
                 * Non-disk-type devices don't need to blacklist any pages
                 * or to force 192-byte transfer lengths for MODE SENSE.
                 * But they do need to use MODE SENSE(10).
                 */
                sdev->use_10_for_ms = 1;

                /* Some (fake) usb cdrom devices don't like READ_DISC_INFO */
                if (us->fflags & US_FL_NO_READ_DISC_INFO)
                        sdev->no_read_disc_info = 1;
        }

        /*
         * The CB and CBI transports have no way to pass LUN values
         * other than the bits in the second byte of a CDB.  But those
         * bits don't get set to the LUN value if the device reports
         * scsi_level == 0 (UNKNOWN).  Hence such devices must necessarily
         * be single-LUN.
         */
        if ((us->protocol == USB_PR_CB || us->protocol == USB_PR_CBI) &&
                        sdev->scsi_level == SCSI_UNKNOWN)
                us->max_lun = 0;

        /*
         * Some devices choke when they receive a PREVENT-ALLOW MEDIUM
         * REMOVAL command, so suppress those commands.
         */
        if (us->fflags & US_FL_NOT_LOCKABLE)
                sdev->lockable = 0;

        /*
         * this is to satisfy the compiler, tho I don't think the 
         * return code is ever checked anywhere.
         */
        return 0;
}

static int target_alloc(struct scsi_target *starget)
{
        struct us_data *us = host_to_us(dev_to_shost(starget->dev.parent));

        /*
         * Some USB drives don't support REPORT LUNS, even though they
         * report a SCSI revision level above 2.  Tell the SCSI layer
         * not to issue that command; it will perform a normal sequential
         * scan instead.
         */
        starget->no_report_luns = 1;

        /*
         * The UFI spec treats the Peripheral Qualifier bits in an
         * INQUIRY result as reserved and requires devices to set them
         * to 0.  However the SCSI spec requires these bits to be set
         * to 3 to indicate when a LUN is not present.
         *
         * Let the scanning code know if this target merely sets
         * Peripheral Device Type to 0x1f to indicate no LUN.
         */
        if (us->subclass == USB_SC_UFI)
                starget->pdt_1f_for_no_lun = 1;

        return 0;
}

/* queue a command */
/* This is always called with scsi_lock(host) held */
static int queuecommand_lck(struct scsi_cmnd *srb,
                        void (*done)(struct scsi_cmnd *))
{
        struct us_data *us = host_to_us(srb->device->host);

        /* check for state-transition errors */
        if (us->srb != NULL) {
                printk(KERN_ERR USB_STORAGE "Error in %s: us->srb = %p\n",
                        __func__, us->srb);
                return SCSI_MLQUEUE_HOST_BUSY;
        }

        /* fail the command if we are disconnecting */
        if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
                usb_stor_dbg(us, "Fail command during disconnect\n");
                srb->result = DID_NO_CONNECT << 16;
                done(srb);
                return 0;
        }

        /* enqueue the command and wake up the control thread */
        srb->scsi_done = done;
        us->srb = srb;
        complete(&us->cmnd_ready);

        return 0;
}

static DEF_SCSI_QCMD(queuecommand)

/***********************************************************************
 * Error handling functions
 ***********************************************************************/

/* Command timeout and abort */
static int command_abort(struct scsi_cmnd *srb)
{
        struct us_data *us = host_to_us(srb->device->host);

        usb_stor_dbg(us, "%s called\n", __func__);

        /*
         * us->srb together with the TIMED_OUT, RESETTING, and ABORTING
         * bits are protected by the host lock.
         */
        scsi_lock(us_to_host(us));

        /* Is this command still active? */
        if (us->srb != srb) {
                scsi_unlock(us_to_host(us));
                usb_stor_dbg(us, "-- nothing to abort\n");
                return FAILED;
        }

        /*
         * Set the TIMED_OUT bit.  Also set the ABORTING bit, but only if
         * a device reset isn't already in progress (to avoid interfering
         * with the reset).  Note that we must retain the host lock while
         * calling usb_stor_stop_transport(); otherwise it might interfere
         * with an auto-reset that begins as soon as we release the lock.
         */
        set_bit(US_FLIDX_TIMED_OUT, &us->dflags);
        if (!test_bit(US_FLIDX_RESETTING, &us->dflags)) {
                set_bit(US_FLIDX_ABORTING, &us->dflags);
                usb_stor_stop_transport(us);
        }
        scsi_unlock(us_to_host(us));

        /* Wait for the aborted command to finish */
        wait_for_completion(&us->notify);
        return SUCCESS;
}

/*
 * This invokes the transport reset mechanism to reset the state of the
 * device
 */
static int device_reset(struct scsi_cmnd *srb)
{
        struct us_data *us = host_to_us(srb->device->host);
        int result;

        usb_stor_dbg(us, "%s called\n", __func__);

        /* lock the device pointers and do the reset */
        mutex_lock(&(us->dev_mutex));
        result = us->transport_reset(us);
        mutex_unlock(&us->dev_mutex);

        return result < 0 ? FAILED : SUCCESS;
}

/* Simulate a SCSI bus reset by resetting the device's USB port. */
static int bus_reset(struct scsi_cmnd *srb)
{
        struct us_data *us = host_to_us(srb->device->host);
        int result;

        usb_stor_dbg(us, "%s called\n", __func__);

        result = usb_stor_port_reset(us);
        return result < 0 ? FAILED : SUCCESS;
}

/*
 * Report a driver-initiated device reset to the SCSI layer.
 * Calling this for a SCSI-initiated reset is unnecessary but harmless.
 * The caller must own the SCSI host lock.
 */
void usb_stor_report_device_reset(struct us_data *us)
{
        int i;
        struct Scsi_Host *host = us_to_host(us);

        scsi_report_device_reset(host, 0, 0);
        if (us->fflags & US_FL_SCM_MULT_TARG) {
                for (i = 1; i < host->max_id; ++i)
                        scsi_report_device_reset(host, 0, i);
        }
}

/*
 * Report a driver-initiated bus reset to the SCSI layer.
 * Calling this for a SCSI-initiated reset is unnecessary but harmless.
 * The caller must not own the SCSI host lock.
 */
void usb_stor_report_bus_reset(struct us_data *us)
{
        struct Scsi_Host *host = us_to_host(us);

        scsi_lock(host);
        scsi_report_bus_reset(host, 0);
        scsi_unlock(host);
}

/***********************************************************************
 * /proc/scsi/ functions
 ***********************************************************************/

static int write_info(struct Scsi_Host *host, char *buffer, int length)
{
        /* if someone is sending us data, just throw it away */
        return length;
}

static int show_info (struct seq_file *m, struct Scsi_Host *host)
{
        struct us_data *us = host_to_us(host);
        const char *string;

        /* print the controller name */
        seq_printf(m, "   Host scsi%d: usb-storage\n", host->host_no);

        /* print product, vendor, and serial number strings */
        if (us->pusb_dev->manufacturer)
                string = us->pusb_dev->manufacturer;
        else if (us->unusual_dev->vendorName)
                string = us->unusual_dev->vendorName;
        else
                string = "Unknown";
        seq_printf(m, "       Vendor: %s\n", string);
        if (us->pusb_dev->product)
                string = us->pusb_dev->product;
        else if (us->unusual_dev->productName)
                string = us->unusual_dev->productName;
        else
                string = "Unknown";
        seq_printf(m, "      Product: %s\n", string);
        if (us->pusb_dev->serial)
                string = us->pusb_dev->serial;
        else
                string = "None";
        seq_printf(m, "Serial Number: %s\n", string);

        /* show the protocol and transport */
        seq_printf(m, "     Protocol: %s\n", us->protocol_name);
        seq_printf(m, "    Transport: %s\n", us->transport_name);

        /* show the device flags */
        seq_printf(m, "       Quirks:");

#define US_FLAG(name, value) \
        if (us->fflags & value) seq_printf(m, " " #name);
US_DO_ALL_FLAGS
#undef US_FLAG
        seq_putc(m, '\n');
        return 0;
}

/***********************************************************************
 * Sysfs interface
 ***********************************************************************/

/* Output routine for the sysfs max_sectors file */
static ssize_t max_sectors_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct scsi_device *sdev = to_scsi_device(dev);

        return sprintf(buf, "%u\n", queue_max_hw_sectors(sdev->request_queue));
}

/* Input routine for the sysfs max_sectors file */
static ssize_t max_sectors_store(struct device *dev, struct device_attribute *attr, const char *buf,
                size_t count)
{
        struct scsi_device *sdev = to_scsi_device(dev);
        unsigned short ms;

        if (sscanf(buf, "%hu", &ms) > 0) {
                blk_queue_max_hw_sectors(sdev->request_queue, ms);
                return count;
        }
        return -EINVAL;
}
static DEVICE_ATTR_RW(max_sectors);

static struct device_attribute *sysfs_device_attr_list[] = {
        &dev_attr_max_sectors,
        NULL,
};

/*
 * this defines our host template, with which we'll allocate hosts
 */

static const struct scsi_host_template usb_stor_host_template = {
        /* basic userland interface stuff */
        .name =                         "usb-storage",
        .proc_name =                    "usb-storage",
        .show_info =                    show_info,
        .write_info =                   write_info,
        .info =                         host_info,

        /* command interface -- queued only */
        .queuecommand =                 queuecommand,

        /* error and abort handlers */
        .eh_abort_handler =             command_abort,
        .eh_device_reset_handler =      device_reset,
        .eh_bus_reset_handler =         bus_reset,

        /* queue commands only, only one command per LUN */
        .can_queue =                    1,
        .cmd_per_lun =                  1,

        /* unknown initiator id */
        .this_id =                      -1,

        .slave_alloc =                  slave_alloc,
        .slave_configure =              slave_configure,
        .target_alloc =                 target_alloc,

        /* lots of sg segments can be handled */
        .sg_tablesize =                 SCSI_MAX_SG_CHAIN_SEGMENTS,


        /*
         * Limit the total size of a transfer to 120 KB.
         *
         * Some devices are known to choke with anything larger. It seems like
         * the problem stems from the fact that original IDE controllers had
         * only an 8-bit register to hold the number of sectors in one transfer
         * and even those couldn't handle a full 256 sectors.
         *
         * Because we want to make sure we interoperate with as many devices as
         * possible, we will maintain a 240 sector transfer size limit for USB
         * Mass Storage devices.
         *
         * Tests show that other operating have similar limits with Microsoft
         * Windows 7 limiting transfers to 128 sectors for both USB2 and USB3
         * and Apple Mac OS X 10.11 limiting transfers to 256 sectors for USB2
         * and 2048 for USB3 devices.
         */
        .max_sectors =                  240,

        /*
         * merge commands... this seems to help performance, but
         * periodically someone should test to see which setting is more
         * optimal.
         */
        .use_clustering =               1,

        /* emulated HBA */
        .emulated =                     1,

        /* we do our own delay after a device or bus reset */
        .skip_settle_delay =            1,

        /* sysfs device attributes */
        .sdev_attrs =                   sysfs_device_attr_list,

        /* module management */
        .module =                       THIS_MODULE
};

void usb_stor_host_template_init(struct scsi_host_template *sht,
                                 const char *name, struct module *owner)
{
        *sht = usb_stor_host_template;
        sht->name = name;
        sht->proc_name = name;
        sht->module = owner;
}
EXPORT_SYMBOL_GPL(usb_stor_host_template_init);

/* To Report "Illegal Request: Invalid Field in CDB */
unsigned char usb_stor_sense_invalidCDB[18] = {
        [0]     = 0x70,                     /* current error */
        [2]     = ILLEGAL_REQUEST,          /* Illegal Request = 0x05 */
        [7]     = 0x0a,                     /* additional length */
        [12]    = 0x24                      /* Invalid Field in CDB */
};
EXPORT_SYMBOL_GPL(usb_stor_sense_invalidCDB);