/* 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/slab.h>
#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)
{
        return "SCSI emulation for USB Mass Storage devices";
}

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));

        /*
         * The UFI spec treates 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 == US_SC_UFI)
                sdev->sdev_target->pdt_1f_for_no_lun = 1;

        return 0;
}

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

        /* Many devices have trouble transfering 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 (sdev->request_queue->max_sectors > max_sectors)
                        blk_queue_max_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_sectors(sdev->request_queue, 0x7FFFFF);
        }

        /* 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 != US_SC_SCSI && us->subclass != US_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 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 report a SCSI revision level above 2 but are
                 * unable to handle the REPORT LUNS command (for which
                 * support is mandatory at level 3).  Since we already have
                 * a Get-Max-LUN request, we won't lose much by setting the
                 * revision level down to 2.  The only devices that would be
                 * affected are those with sparse LUNs. */
                if (sdev->scsi_level > SCSI_2)
                        sdev->sdev_target->scsi_level =
                                        sdev->scsi_level = SCSI_2;

                /* 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 negible 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 == US_PR_BULK)
                        us->use_last_sector_hacks = 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;
        }

        /* 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 == US_PR_CB || us->protocol == US_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;
}

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

        US_DEBUGP("%s called\n", __func__);

        /* 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)) {
                US_DEBUGP("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;
}

/***********************************************************************
 * 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);

        US_DEBUGP("%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));
                US_DEBUGP ("-- 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;

        US_DEBUGP("%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;

        US_DEBUGP("%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
 ***********************************************************************/

/* we use this macro to help us write into the buffer */
#undef SPRINTF
#define SPRINTF(args...) \
        do { if (pos < buffer+length) pos += sprintf(pos, ## args); } while (0)

static int proc_info (struct Scsi_Host *host, char *buffer,
                char **start, off_t offset, int length, int inout)
{
        struct us_data *us = host_to_us(host);
        char *pos = buffer;
        const char *string;

        /* if someone is sending us data, just throw it away */
        if (inout)
                return length;

        /* print the controller name */
        SPRINTF("   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";
        SPRINTF("       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";
        SPRINTF("      Product: %s\n", string);
        if (us->pusb_dev->serial)
                string = us->pusb_dev->serial;
        else
                string = "None";
        SPRINTF("Serial Number: %s\n", string);

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

        /* show the device flags */
        if (pos < buffer + length) {
                pos += sprintf(pos, "       Quirks:");

#define US_FLAG(name, value) \
        if (us->fflags & value) pos += sprintf(pos, " " #name);
US_DO_ALL_FLAGS
#undef US_FLAG

                *(pos++) = '\n';
        }

        /*
         * Calculate start of next buffer, and return value.
         */
        *start = buffer + offset;

        if ((pos - buffer) < offset)
                return (0);
        else if ((pos - buffer - offset) < length)
                return (pos - buffer - offset);
        else
                return (length);
}

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

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

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

/* Input routine for the sysfs max_sectors file */
static ssize_t store_max_sectors(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 && ms <= SCSI_DEFAULT_MAX_SECTORS) {
                blk_queue_max_sectors(sdev->request_queue, ms);
                return strlen(buf);
        }
        return -EINVAL; 
}

static DEVICE_ATTR(max_sectors, S_IRUGO | S_IWUSR, show_max_sectors,
                store_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
 */

struct scsi_host_template usb_stor_host_template = {
        /* basic userland interface stuff */
        .name =                         "usb-storage",
        .proc_name =                    "usb-storage",
        .proc_info =                    proc_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,

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

        /* limit the total size of a transfer to 120 KB */
        .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
};

/* 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 */
};