scsiglue.c

Go to the documentation of this file.

/* Driver for USB Mass Storage compliant devices
 * SCSI layer glue code
 *
 * Current development and maintenance by:
 *   (c) 1999-2002 Matthew Dharm ([email protected])
 *
 * Developed with the assistance of:
 *   (c) 2000 David L. Brown, Jr. ([email protected])
 *   (c) 2000 Stephen J. Gowdy ([email protected])
 *
 * Initial work by:
 *   (c) 1999 Michael Gee ([email protected])
 *
 * 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)
{
    /*
     * 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));

    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);
    }

    /* 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.
         */
        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 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 == 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;

    } 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);

    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;
}

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);

    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", queue_max_hw_sectors(sdev->request_queue));
}

/* 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) {
        blk_queue_max_hw_sectors(sdev->request_queue, ms);
        return count;
    }
    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,
    .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 */
    .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 */
};
EXPORT_SYMBOL_GPL(usb_stor_sense_invalidCDB);