scsiglue.c

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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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 "transport.h"

/* Host functions */
/*
 * host_info()
 */
static const char *host_info(struct Scsi_Host *host)
{
    /* pr_info("scsiglue --- host_info\n"); */
    return "SCSI emulation for USB Mass Storage devices";
}

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

    /* pr_info("scsiglue --- slave_alloc\n"); */
    sdev->inquiry_len = 36;

    blk_queue_update_dma_alignment(sdev->request_queue, (512 - 1));

    if (us->subclass == USB_SC_UFI)
        sdev->sdev_target->pdt_1f_for_no_lun = 1;

    return 0;
}

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

    /* pr_info("scsiglue --- slave_configure\n"); */
    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_sectors(sdev->request_queue) > max_sectors)
            blk_queue_max_hw_sectors(sdev->request_queue,
                          max_sectors);
    }

    if (sdev->type == TYPE_DISK) {
        if (us->subclass != USB_SC_SCSI &&
            us->subclass != USB_SC_CYP_ATACB)
            sdev->use_10_for_ms = 1;
        sdev->use_192_bytes_for_3f = 1;
        if (us->fflags & US_FL_NO_WP_DETECT)
            sdev->skip_ms_page_3f = 1;
        sdev->skip_ms_page_8 = 1;
        if (us->fflags & US_FL_FIX_CAPACITY)
            sdev->fix_capacity = 1;
        if (us->fflags & US_FL_CAPACITY_HEURISTICS)
            sdev->guess_capacity = 1;
        if (sdev->scsi_level > SCSI_2)
            sdev->sdev_target->scsi_level = sdev->scsi_level = SCSI_2;
        sdev->retry_hwerror = 1;
        sdev->allow_restart = 1;
        sdev->last_sector_bug = 1;
    } else {
        sdev->use_10_for_ms = 1;
    }

    if ((us->protocol == USB_PR_CB || us->protocol == USB_PR_CBI) &&
                    sdev->scsi_level == SCSI_UNKNOWN)
        us->max_lun = 0;

    if (us->fflags & US_FL_NOT_LOCKABLE)
        sdev->lockable = 0;

    return 0;
}

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

    /* pr_info("scsiglue --- queuecommand\n"); */

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

    /* fail the command if we are disconnecting */
    if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
        pr_info("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 */
/*
 * command_abort()
 */
static int command_abort(struct scsi_cmnd *srb)
{
    struct us_data *us = host_to_us(srb->device->host);

    /* pr_info("scsiglue --- command_abort\n"); */

    scsi_lock(us_to_host(us));
    if (us->srb != srb) {
        scsi_unlock(us_to_host(us));
        printk("-- nothing to abort\n");
        return FAILED;
    }

    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.
 */
/*
 * device_reset()
 */
static int device_reset(struct scsi_cmnd *srb)
{
    struct us_data *us = host_to_us(srb->device->host);
    int result;

    /* pr_info("scsiglue --- device_reset\n"); */

    /* 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;
}

/*
 * bus_reset()
 */
static int bus_reset(struct scsi_cmnd *srb)
{
    struct us_data *us = host_to_us(srb->device->host);
    int result;

    /* pr_info("scsiglue --- bus_reset\n"); */
    result = usb_stor_port_reset(us);
    return result < 0 ? FAILED : SUCCESS;
}

/*
 * usb_stor_report_device_reset()
 */
void usb_stor_report_device_reset(struct us_data *us)
{
    int i;
    struct Scsi_Host *host = us_to_host(us);

    /* pr_info("scsiglue --- usb_stor_report_device_reset\n"); */
    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);
    }
}

/*
 * usb_stor_report_bus_reset()
 */
void usb_stor_report_bus_reset(struct us_data *us)
{
    struct Scsi_Host *host = us_to_host(us);

    /* pr_info("scsiglue --- usb_stor_report_bus_reset\n"); */
    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)

/*
 * proc_info()
 */
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;

    /* pr_info("scsiglue --- proc_info\n"); */
    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) \
    do { \
        if (us->fflags & value) \
            pos += sprintf(pos, " " #name); \
    } while (0);
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 */
/*
 * show_max_sectors()
 */
static ssize_t show_max_sectors(struct device *dev,
                struct device_attribute *attr, char *buf)
{
    struct scsi_device *sdev = to_scsi_device(dev);

    /* pr_info("scsiglue --- ssize_t show_max_sectors\n"); */
    return sprintf(buf, "%u\n", queue_max_sectors(sdev->request_queue));
}

/* Input routine for the sysfs max_sectors file */
/*
 * store_max_sectors()
 */
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;

    /* pr_info("scsiglue --- ssize_t store_max_sectors\n"); */
    if (sscanf(buf, "%hu", &ms) > 0 && ms <= SCSI_DEFAULT_MAX_SECTORS) {
        blk_queue_max_hw_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 */

/*
 * usb_stor_host_template()
 */
struct scsi_host_template usb_stor_host_template = {
    /* basic userland interface stuff */
    .name =             "eucr-storage",
    .proc_name =            "eucr-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 */
};

/***********************************************************************
 * Scatter-gather transfer buffer access routines
 ***********************************************************************/

/*
 * usb_stor_access_xfer_buf()
 */
unsigned int usb_stor_access_xfer_buf(struct us_data *us, unsigned char *buffer,
    unsigned int buflen, struct scsi_cmnd *srb, struct scatterlist **sgptr,
    unsigned int *offset, enum xfer_buf_dir dir)
{
    unsigned int cnt;

    /* pr_info("transport --- usb_stor_access_xfer_buf\n"); */
    struct scatterlist *sg = *sgptr;

    if (!sg)
        sg = scsi_sglist(srb);

    cnt = 0;
    while (cnt < buflen && sg) {
        struct page *page = sg_page(sg) +
                    ((sg->offset + *offset) >> PAGE_SHIFT);
        unsigned int poff = (sg->offset + *offset) & (PAGE_SIZE-1);
        unsigned int sglen = sg->length - *offset;

        if (sglen > buflen - cnt) {
            /* Transfer ends within this s-g entry */
            sglen = buflen - cnt;
            *offset += sglen;
        } else {
            /* Transfer continues to next s-g entry */
            *offset = 0;
            sg = sg_next(sg);
        }

        while (sglen > 0) {
            unsigned int plen = min(sglen,
                        (unsigned int)PAGE_SIZE - poff);
            unsigned char *ptr = kmap(page);

            if (dir == TO_XFER_BUF)
                memcpy(ptr + poff, buffer + cnt, plen);
            else
                memcpy(buffer + cnt, ptr + poff, plen);
            kunmap(page);

            /* Start at the beginning of the next page */
            poff = 0;
            ++page;
            cnt += plen;
            sglen -= plen;
        }
    }
    *sgptr = sg;

    /* Return the amount actually transferred */
    return cnt;
}

/*
 * Store the contents of buffer into srb's transfer
 * buffer and set the SCSI residue.
 */
/*
 * usb_stor_set_xfer_buf()
 */
void usb_stor_set_xfer_buf(struct us_data *us, unsigned char *buffer,
        unsigned int buflen, struct scsi_cmnd *srb, unsigned int dir)
{
    unsigned int offset = 0;
    struct scatterlist *sg = NULL;

    /* pr_info("transport --- usb_stor_set_xfer_buf\n"); */
    /* TO_XFER_BUF = 0, FROM_XFER_BUF = 1 */
    buflen = min(buflen, scsi_bufflen(srb));
    buflen = usb_stor_access_xfer_buf(us, buffer, buflen, srb,
                        &sg, &offset, dir);
    if (buflen < scsi_bufflen(srb))
        scsi_set_resid(srb, scsi_bufflen(srb) - buflen);
}