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transport.c

/* Driver for USB Mass Storage compliant devices
 *
 * $Id: transport.c,v 1.47 2002/04/22 03:39:43 mdharm Exp $
 *
 * 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)
 *   (c) 2002 Alan Stern <stern@rowland.org>
 *
 * 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/sched.h>
#include <linux/errno.h>
#include <linux/slab.h>

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

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


/***********************************************************************
 * Data transfer routines
 ***********************************************************************/

/*
 * This is subtle, so pay attention:
 * ---------------------------------
 * We're very concerned about races with a command abort.  Hanging this code
 * is a sure fire way to hang the kernel.  (Note that this discussion applies
 * only to transactions resulting from a scsi queued-command, since only
 * these transactions are subject to a scsi abort.  Other transactions, such
 * as those occurring during device-specific initialization, must be handled
 * by a separate code path.)
 *
 * The abort function (usb_storage_command_abort() in scsiglue.c) first
 * sets the machine state and the ABORTING bit in us->flags to prevent
 * new URBs from being submitted.  It then calls usb_stor_stop_transport()
 * below, which atomically tests-and-clears the URB_ACTIVE bit in us->flags
 * to see if the current_urb needs to be stopped.  Likewise, the SG_ACTIVE
 * bit is tested to see if the current_sg scatter-gather request needs to be
 * stopped.  The timeout callback routine does much the same thing.
 *
 * When a disconnect occurs, the DISCONNECTING bit in us->flags is set to
 * prevent new URBs from being submitted, and usb_stor_stop_transport() is
 * called to stop any ongoing requests.
 *
 * The submit function first verifies that the submitting is allowed
 * (neither ABORTING nor DISCONNECTING bits are set) and that the submit
 * completes without errors, and only then sets the URB_ACTIVE bit.  This
 * prevents the stop_transport() function from trying to cancel the URB
 * while the submit call is underway.  Next, the submit function must test
 * the flags to see if an abort or disconnect occurred during the submission
 * or before the URB_ACTIVE bit was set.  If so, it's essential to cancel
 * the URB if it hasn't been cancelled already (i.e., if the URB_ACTIVE bit
 * is still set).  Either way, the function must then wait for the URB to
 * finish.  Note that the URB can still be in progress even after a call to
 * usb_unlink_urb() returns.
 *
 * The idea is that (1) once the ABORTING or DISCONNECTING bit is set,
 * either the stop_transport() function or the submitting function
 * is guaranteed to call usb_unlink_urb() for an active URB,
 * and (2) test_and_clear_bit() prevents usb_unlink_urb() from being
 * called more than once or from being called during usb_submit_urb().
 */

/* This is the completion handler which will wake us up when an URB
 * completes.
 */
static void usb_stor_blocking_completion(struct urb *urb)
{
      struct completion *urb_done_ptr = (struct completion *)urb->context;

      complete(urb_done_ptr);
}

/* This is the common part of the URB message submission code
 *
 * All URBs from the usb-storage driver involved in handling a queued scsi
 * command _must_ pass through this function (or something like it) for the
 * abort mechanisms to work properly.
 */
static int usb_stor_msg_common(struct us_data *us, int timeout)
{
      struct completion urb_done;
      long timeleft;
      int status;

      /* don't submit URBs during abort/disconnect processing */
      if (us->flags & ABORTING_OR_DISCONNECTING)
            return -EIO;

      /* set up data structures for the wakeup system */
      init_completion(&urb_done);

      /* fill the common fields in the URB */
      us->current_urb->context = &urb_done;
      us->current_urb->actual_length = 0;
      us->current_urb->error_count = 0;
      us->current_urb->status = 0;

      /* we assume that if transfer_buffer isn't us->iobuf then it
       * hasn't been mapped for DMA.  Yes, this is clunky, but it's
       * easier than always having the caller tell us whether the
       * transfer buffer has already been mapped. */
      us->current_urb->transfer_flags = URB_NO_SETUP_DMA_MAP;
      if (us->current_urb->transfer_buffer == us->iobuf)
            us->current_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
      us->current_urb->transfer_dma = us->iobuf_dma;
      us->current_urb->setup_dma = us->cr_dma;

      /* submit the URB */
      status = usb_submit_urb(us->current_urb, GFP_NOIO);
      if (status) {
            /* something went wrong */
            return status;
      }

      /* since the URB has been submitted successfully, it's now okay
       * to cancel it */
      set_bit(US_FLIDX_URB_ACTIVE, &us->flags);

      /* did an abort/disconnect occur during the submission? */
      if (us->flags & ABORTING_OR_DISCONNECTING) {

            /* cancel the URB, if it hasn't been cancelled already */
            if (test_and_clear_bit(US_FLIDX_URB_ACTIVE, &us->flags)) {
                  US_DEBUGP("-- cancelling URB\n");
                  usb_unlink_urb(us->current_urb);
            }
      }
 
      /* wait for the completion of the URB */
      timeleft = wait_for_completion_interruptible_timeout(
                  &urb_done, timeout ? : MAX_SCHEDULE_TIMEOUT);
 
      clear_bit(US_FLIDX_URB_ACTIVE, &us->flags);

      if (timeleft <= 0) {
            US_DEBUGP("%s -- cancelling URB\n",
                    timeleft == 0 ? "Timeout" : "Signal");
            usb_kill_urb(us->current_urb);
      }

      /* return the URB status */
      return us->current_urb->status;
}

/*
 * Transfer one control message, with timeouts, and allowing early
 * termination.  Return codes are usual -Exxx, *not* USB_STOR_XFER_xxx.
 */
int usb_stor_control_msg(struct us_data *us, unsigned int pipe,
             u8 request, u8 requesttype, u16 value, u16 index, 
             void *data, u16 size, int timeout)
{
      int status;

      US_DEBUGP("%s: rq=%02x rqtype=%02x value=%04x index=%02x len=%u\n",
                  __FUNCTION__, request, requesttype,
                  value, index, size);

      /* fill in the devrequest structure */
      us->cr->bRequestType = requesttype;
      us->cr->bRequest = request;
      us->cr->wValue = cpu_to_le16(value);
      us->cr->wIndex = cpu_to_le16(index);
      us->cr->wLength = cpu_to_le16(size);

      /* fill and submit the URB */
      usb_fill_control_urb(us->current_urb, us->pusb_dev, pipe, 
                   (unsigned char*) us->cr, data, size, 
                   usb_stor_blocking_completion, NULL);
      status = usb_stor_msg_common(us, timeout);

      /* return the actual length of the data transferred if no error */
      if (status == 0)
            status = us->current_urb->actual_length;
      return status;
}

/* This is a version of usb_clear_halt() that allows early termination and
 * doesn't read the status from the device -- this is because some devices
 * crash their internal firmware when the status is requested after a halt.
 *
 * A definitive list of these 'bad' devices is too difficult to maintain or
 * make complete enough to be useful.  This problem was first observed on the
 * Hagiwara FlashGate DUAL unit.  However, bus traces reveal that neither
 * MacOS nor Windows checks the status after clearing a halt.
 *
 * Since many vendors in this space limit their testing to interoperability
 * with these two OSes, specification violations like this one are common.
 */
int usb_stor_clear_halt(struct us_data *us, unsigned int pipe)
{
      int result;
      int endp = usb_pipeendpoint(pipe);

      if (usb_pipein (pipe))
            endp |= USB_DIR_IN;

      result = usb_stor_control_msg(us, us->send_ctrl_pipe,
            USB_REQ_CLEAR_FEATURE, USB_RECIP_ENDPOINT,
            USB_ENDPOINT_HALT, endp,
            NULL, 0, 3*HZ);

      /* reset the endpoint toggle */
      if (result >= 0)
            usb_settoggle(us->pusb_dev, usb_pipeendpoint(pipe),
                        usb_pipeout(pipe), 0);

      US_DEBUGP("%s: result = %d\n", __FUNCTION__, result);
      return result;
}


/*
 * Interpret the results of a URB transfer
 *
 * This function prints appropriate debugging messages, clears halts on
 * non-control endpoints, and translates the status to the corresponding
 * USB_STOR_XFER_xxx return code.
 */
static int interpret_urb_result(struct us_data *us, unsigned int pipe,
            unsigned int length, int result, unsigned int partial)
{
      US_DEBUGP("Status code %d; transferred %u/%u\n",
                  result, partial, length);
      switch (result) {

      /* no error code; did we send all the data? */
      case 0:
            if (partial != length) {
                  US_DEBUGP("-- short transfer\n");
                  return USB_STOR_XFER_SHORT;
            }

            US_DEBUGP("-- transfer complete\n");
            return USB_STOR_XFER_GOOD;

      /* stalled */
      case -EPIPE:
            /* for control endpoints, (used by CB[I]) a stall indicates
             * a failed command */
            if (usb_pipecontrol(pipe)) {
                  US_DEBUGP("-- stall on control pipe\n");
                  return USB_STOR_XFER_STALLED;
            }

            /* for other sorts of endpoint, clear the stall */
            US_DEBUGP("clearing endpoint halt for pipe 0x%x\n", pipe);
            if (usb_stor_clear_halt(us, pipe) < 0)
                  return USB_STOR_XFER_ERROR;
            return USB_STOR_XFER_STALLED;

      /* babble - the device tried to send more than we wanted to read */
      case -EOVERFLOW:
            US_DEBUGP("-- babble\n");
            return USB_STOR_XFER_LONG;

      /* the transfer was cancelled by abort, disconnect, or timeout */
      case -ECONNRESET:
            US_DEBUGP("-- transfer cancelled\n");
            return USB_STOR_XFER_ERROR;

      /* short scatter-gather read transfer */
      case -EREMOTEIO:
            US_DEBUGP("-- short read transfer\n");
            return USB_STOR_XFER_SHORT;

      /* abort or disconnect in progress */
      case -EIO:
            US_DEBUGP("-- abort or disconnect in progress\n");
            return USB_STOR_XFER_ERROR;

      /* the catch-all error case */
      default:
            US_DEBUGP("-- unknown error\n");
            return USB_STOR_XFER_ERROR;
      }
}

/*
 * Transfer one control message, without timeouts, but allowing early
 * termination.  Return codes are USB_STOR_XFER_xxx.
 */
int usb_stor_ctrl_transfer(struct us_data *us, unsigned int pipe,
            u8 request, u8 requesttype, u16 value, u16 index,
            void *data, u16 size)
{
      int result;

      US_DEBUGP("%s: rq=%02x rqtype=%02x value=%04x index=%02x len=%u\n",
                  __FUNCTION__, request, requesttype,
                  value, index, size);

      /* fill in the devrequest structure */
      us->cr->bRequestType = requesttype;
      us->cr->bRequest = request;
      us->cr->wValue = cpu_to_le16(value);
      us->cr->wIndex = cpu_to_le16(index);
      us->cr->wLength = cpu_to_le16(size);

      /* fill and submit the URB */
      usb_fill_control_urb(us->current_urb, us->pusb_dev, pipe, 
                   (unsigned char*) us->cr, data, size, 
                   usb_stor_blocking_completion, NULL);
      result = usb_stor_msg_common(us, 0);

      return interpret_urb_result(us, pipe, size, result,
                  us->current_urb->actual_length);
}

/*
 * Receive one interrupt buffer, without timeouts, but allowing early
 * termination.  Return codes are USB_STOR_XFER_xxx.
 *
 * This routine always uses us->recv_intr_pipe as the pipe and
 * us->ep_bInterval as the interrupt interval.
 */
static int usb_stor_intr_transfer(struct us_data *us, void *buf,
                          unsigned int length)
{
      int result;
      unsigned int pipe = us->recv_intr_pipe;
      unsigned int maxp;

      US_DEBUGP("%s: xfer %u bytes\n", __FUNCTION__, length);

      /* calculate the max packet size */
      maxp = usb_maxpacket(us->pusb_dev, pipe, usb_pipeout(pipe));
      if (maxp > length)
            maxp = length;

      /* fill and submit the URB */
      usb_fill_int_urb(us->current_urb, us->pusb_dev, pipe, buf,
                  maxp, usb_stor_blocking_completion, NULL,
                  us->ep_bInterval);
      result = usb_stor_msg_common(us, 0);

      return interpret_urb_result(us, pipe, length, result,
                  us->current_urb->actual_length);
}

/*
 * Transfer one buffer via bulk pipe, without timeouts, but allowing early
 * termination.  Return codes are USB_STOR_XFER_xxx.  If the bulk pipe
 * stalls during the transfer, the halt is automatically cleared.
 */
int usb_stor_bulk_transfer_buf(struct us_data *us, unsigned int pipe,
      void *buf, unsigned int length, unsigned int *act_len)
{
      int result;

      US_DEBUGP("%s: xfer %u bytes\n", __FUNCTION__, length);

      /* fill and submit the URB */
      usb_fill_bulk_urb(us->current_urb, us->pusb_dev, pipe, buf, length,
                  usb_stor_blocking_completion, NULL);
      result = usb_stor_msg_common(us, 0);

      /* store the actual length of the data transferred */
      if (act_len)
            *act_len = us->current_urb->actual_length;
      return interpret_urb_result(us, pipe, length, result, 
                  us->current_urb->actual_length);
}

/*
 * Transfer a scatter-gather list via bulk transfer
 *
 * This function does basically the same thing as usb_stor_bulk_transfer_buf()
 * above, but it uses the usbcore scatter-gather library.
 */
static int usb_stor_bulk_transfer_sglist(struct us_data *us, unsigned int pipe,
            struct scatterlist *sg, int num_sg, unsigned int length,
            unsigned int *act_len)
{
      int result;

      /* don't submit s-g requests during abort/disconnect processing */
      if (us->flags & ABORTING_OR_DISCONNECTING)
            return USB_STOR_XFER_ERROR;

      /* initialize the scatter-gather request block */
      US_DEBUGP("%s: xfer %u bytes, %d entries\n", __FUNCTION__,
                  length, num_sg);
      result = usb_sg_init(&us->current_sg, us->pusb_dev, pipe, 0,
                  sg, num_sg, length, GFP_NOIO);
      if (result) {
            US_DEBUGP("usb_sg_init returned %d\n", result);
            return USB_STOR_XFER_ERROR;
      }

      /* since the block has been initialized successfully, it's now
       * okay to cancel it */
      set_bit(US_FLIDX_SG_ACTIVE, &us->flags);

      /* did an abort/disconnect occur during the submission? */
      if (us->flags & ABORTING_OR_DISCONNECTING) {

            /* cancel the request, if it hasn't been cancelled already */
            if (test_and_clear_bit(US_FLIDX_SG_ACTIVE, &us->flags)) {
                  US_DEBUGP("-- cancelling sg request\n");
                  usb_sg_cancel(&us->current_sg);
            }
      }

      /* wait for the completion of the transfer */
      usb_sg_wait(&us->current_sg);
      clear_bit(US_FLIDX_SG_ACTIVE, &us->flags);

      result = us->current_sg.status;
      if (act_len)
            *act_len = us->current_sg.bytes;
      return interpret_urb_result(us, pipe, length, result,
                  us->current_sg.bytes);
}

/*
 * Transfer an entire SCSI command's worth of data payload over the bulk
 * pipe.
 *
 * Note that this uses usb_stor_bulk_transfer_buf() and
 * usb_stor_bulk_transfer_sglist() to achieve its goals --
 * this function simply determines whether we're going to use
 * scatter-gather or not, and acts appropriately.
 */
int usb_stor_bulk_transfer_sg(struct us_data* us, unsigned int pipe,
            void *buf, unsigned int length_left, int use_sg, int *residual)
{
      int result;
      unsigned int partial;

      /* are we scatter-gathering? */
      if (use_sg) {
            /* use the usb core scatter-gather primitives */
            result = usb_stor_bulk_transfer_sglist(us, pipe,
                        (struct scatterlist *) buf, use_sg,
                        length_left, &partial);
            length_left -= partial;
      } else {
            /* no scatter-gather, just make the request */
            result = usb_stor_bulk_transfer_buf(us, pipe, buf, 
                        length_left, &partial);
            length_left -= partial;
      }

      /* store the residual and return the error code */
      if (residual)
            *residual = length_left;
      return result;
}

/***********************************************************************
 * Transport routines
 ***********************************************************************/

/* Invoke the transport and basic error-handling/recovery methods
 *
 * This is used by the protocol layers to actually send the message to
 * the device and receive the response.
 */
void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
{
      int need_auto_sense;
      int result;

      /* send the command to the transport layer */
      srb->resid = 0;
      result = us->transport(srb, us);

      /* if the command gets aborted by the higher layers, we need to
       * short-circuit all other processing
       */
      if (test_bit(US_FLIDX_TIMED_OUT, &us->flags)) {
            US_DEBUGP("-- command was aborted\n");
            srb->result = DID_ABORT << 16;
            goto Handle_Errors;
      }

      /* if there is a transport error, reset and don't auto-sense */
      if (result == USB_STOR_TRANSPORT_ERROR) {
            US_DEBUGP("-- transport indicates error, resetting\n");
            srb->result = DID_ERROR << 16;
            goto Handle_Errors;
      }

      /* if the transport provided its own sense data, don't auto-sense */
      if (result == USB_STOR_TRANSPORT_NO_SENSE) {
            srb->result = SAM_STAT_CHECK_CONDITION;
            return;
      }

      srb->result = SAM_STAT_GOOD;

      /* Determine if we need to auto-sense
       *
       * I normally don't use a flag like this, but it's almost impossible
       * to understand what's going on here if I don't.
       */
      need_auto_sense = 0;

      /*
       * If we're running the CB transport, which is incapable
       * of determining status on its own, we will auto-sense
       * unless the operation involved a data-in transfer.  Devices
       * can signal most data-in errors by stalling the bulk-in pipe.
       */
      if ((us->protocol == US_PR_CB || us->protocol == US_PR_DPCM_USB) &&
                  srb->sc_data_direction != DMA_FROM_DEVICE) {
            US_DEBUGP("-- CB transport device requiring auto-sense\n");
            need_auto_sense = 1;
      }

      /*
       * If we have a failure, we're going to do a REQUEST_SENSE 
       * automatically.  Note that we differentiate between a command
       * "failure" and an "error" in the transport mechanism.
       */
      if (result == USB_STOR_TRANSPORT_FAILED) {
            US_DEBUGP("-- transport indicates command failure\n");
            need_auto_sense = 1;
      }

      /*
       * A short transfer on a command where we don't expect it
       * is unusual, but it doesn't mean we need to auto-sense.
       */
      if ((srb->resid > 0) &&
          !((srb->cmnd[0] == REQUEST_SENSE) ||
            (srb->cmnd[0] == INQUIRY) ||
            (srb->cmnd[0] == MODE_SENSE) ||
            (srb->cmnd[0] == LOG_SENSE) ||
            (srb->cmnd[0] == MODE_SENSE_10))) {
            US_DEBUGP("-- unexpectedly short transfer\n");
      }

      /* Now, if we need to do the auto-sense, let's do it */
      if (need_auto_sense) {
            int temp_result;
            struct scsi_eh_save ses;

            US_DEBUGP("Issuing auto-REQUEST_SENSE\n");

            scsi_eh_prep_cmnd(srb, &ses, NULL, 0, US_SENSE_SIZE);

            /* FIXME: we must do the protocol translation here */
            if (us->subclass == US_SC_RBC || us->subclass == US_SC_SCSI)
                  srb->cmd_len = 6;
            else
                  srb->cmd_len = 12;

            /* issue the auto-sense command */
            srb->resid = 0;
            temp_result = us->transport(us->srb, us);

            /* let's clean up right away */
            scsi_eh_restore_cmnd(srb, &ses);

            if (test_bit(US_FLIDX_TIMED_OUT, &us->flags)) {
                  US_DEBUGP("-- auto-sense aborted\n");
                  srb->result = DID_ABORT << 16;
                  goto Handle_Errors;
            }
            if (temp_result != USB_STOR_TRANSPORT_GOOD) {
                  US_DEBUGP("-- auto-sense failure\n");

                  /* we skip the reset if this happens to be a
                   * multi-target device, since failure of an
                   * auto-sense is perfectly valid
                   */
                  srb->result = DID_ERROR << 16;
                  if (!(us->flags & US_FL_SCM_MULT_TARG))
                        goto Handle_Errors;
                  return;
            }

            US_DEBUGP("-- Result from auto-sense is %d\n", temp_result);
            US_DEBUGP("-- code: 0x%x, key: 0x%x, ASC: 0x%x, ASCQ: 0x%x\n",
                    srb->sense_buffer[0],
                    srb->sense_buffer[2] & 0xf,
                    srb->sense_buffer[12], 
                    srb->sense_buffer[13]);
#ifdef CONFIG_USB_STORAGE_DEBUG
            usb_stor_show_sense(
                    srb->sense_buffer[2] & 0xf,
                    srb->sense_buffer[12], 
                    srb->sense_buffer[13]);
#endif

            /* set the result so the higher layers expect this data */
            srb->result = SAM_STAT_CHECK_CONDITION;

            /* If things are really okay, then let's show that.  Zero
             * out the sense buffer so the higher layers won't realize
             * we did an unsolicited auto-sense. */
            if (result == USB_STOR_TRANSPORT_GOOD &&
                  /* Filemark 0, ignore EOM, ILI 0, no sense */
                        (srb->sense_buffer[2] & 0xaf) == 0 &&
                  /* No ASC or ASCQ */
                        srb->sense_buffer[12] == 0 &&
                        srb->sense_buffer[13] == 0) {
                  srb->result = SAM_STAT_GOOD;
                  srb->sense_buffer[0] = 0x0;
            }
      }

      /* Did we transfer less than the minimum amount required? */
      if (srb->result == SAM_STAT_GOOD &&
                  srb->request_bufflen - srb->resid < srb->underflow)
            srb->result = (DID_ERROR << 16) | (SUGGEST_RETRY << 24);

      return;

      /* Error and abort processing: try to resynchronize with the device
       * by issuing a port reset.  If that fails, try a class-specific
       * device reset. */
  Handle_Errors:

      /* Set the RESETTING bit, and clear the ABORTING bit so that
       * the reset may proceed. */
      scsi_lock(us_to_host(us));
      set_bit(US_FLIDX_RESETTING, &us->flags);
      clear_bit(US_FLIDX_ABORTING, &us->flags);
      scsi_unlock(us_to_host(us));

      /* We must release the device lock because the pre_reset routine
       * will want to acquire it. */
      mutex_unlock(&us->dev_mutex);
      result = usb_stor_port_reset(us);
      mutex_lock(&us->dev_mutex);

      if (result < 0) {
            scsi_lock(us_to_host(us));
            usb_stor_report_device_reset(us);
            scsi_unlock(us_to_host(us));
            us->transport_reset(us);
      }
      clear_bit(US_FLIDX_RESETTING, &us->flags);
}

/* Stop the current URB transfer */
void usb_stor_stop_transport(struct us_data *us)
{
      US_DEBUGP("%s called\n", __FUNCTION__);

      /* If the state machine is blocked waiting for an URB,
       * let's wake it up.  The test_and_clear_bit() call
       * guarantees that if a URB has just been submitted,
       * it won't be cancelled more than once. */
      if (test_and_clear_bit(US_FLIDX_URB_ACTIVE, &us->flags)) {
            US_DEBUGP("-- cancelling URB\n");
            usb_unlink_urb(us->current_urb);
      }

      /* If we are waiting for a scatter-gather operation, cancel it. */
      if (test_and_clear_bit(US_FLIDX_SG_ACTIVE, &us->flags)) {
            US_DEBUGP("-- cancelling sg request\n");
            usb_sg_cancel(&us->current_sg);
      }
}

/*
 * Control/Bulk/Interrupt transport
 */

int usb_stor_CBI_transport(struct scsi_cmnd *srb, struct us_data *us)
{
      unsigned int transfer_length = srb->request_bufflen;
      unsigned int pipe = 0;
      int result;

      /* COMMAND STAGE */
      /* let's send the command via the control pipe */
      result = usb_stor_ctrl_transfer(us, us->send_ctrl_pipe,
                              US_CBI_ADSC, 
                              USB_TYPE_CLASS | USB_RECIP_INTERFACE, 0, 
                              us->ifnum, srb->cmnd, srb->cmd_len);

      /* check the return code for the command */
      US_DEBUGP("Call to usb_stor_ctrl_transfer() returned %d\n", result);

      /* if we stalled the command, it means command failed */
      if (result == USB_STOR_XFER_STALLED) {
            return USB_STOR_TRANSPORT_FAILED;
      }

      /* Uh oh... serious problem here */
      if (result != USB_STOR_XFER_GOOD) {
            return USB_STOR_TRANSPORT_ERROR;
      }

      /* DATA STAGE */
      /* transfer the data payload for this command, if one exists*/
      if (transfer_length) {
            pipe = srb->sc_data_direction == DMA_FROM_DEVICE ? 
                        us->recv_bulk_pipe : us->send_bulk_pipe;
            result = usb_stor_bulk_transfer_sg(us, pipe,
                              srb->request_buffer, transfer_length,
                              srb->use_sg, &srb->resid);
            US_DEBUGP("CBI data stage result is 0x%x\n", result);

            /* if we stalled the data transfer it means command failed */
            if (result == USB_STOR_XFER_STALLED)
                  return USB_STOR_TRANSPORT_FAILED;
            if (result > USB_STOR_XFER_STALLED)
                  return USB_STOR_TRANSPORT_ERROR;
      }

      /* STATUS STAGE */
      result = usb_stor_intr_transfer(us, us->iobuf, 2);
      US_DEBUGP("Got interrupt data (0x%x, 0x%x)\n", 
                  us->iobuf[0], us->iobuf[1]);
      if (result != USB_STOR_XFER_GOOD)
            return USB_STOR_TRANSPORT_ERROR;

      /* UFI gives us ASC and ASCQ, like a request sense
       *
       * REQUEST_SENSE and INQUIRY don't affect the sense data on UFI
       * devices, so we ignore the information for those commands.  Note
       * that this means we could be ignoring a real error on these
       * commands, but that can't be helped.
       */
      if (us->subclass == US_SC_UFI) {
            if (srb->cmnd[0] == REQUEST_SENSE ||
                srb->cmnd[0] == INQUIRY)
                  return USB_STOR_TRANSPORT_GOOD;
            if (us->iobuf[0])
                  goto Failed;
            return USB_STOR_TRANSPORT_GOOD;
      }

      /* If not UFI, we interpret the data as a result code 
       * The first byte should always be a 0x0.
       *
       * Some bogus devices don't follow that rule.  They stuff the ASC
       * into the first byte -- so if it's non-zero, call it a failure.
       */
      if (us->iobuf[0]) {
            US_DEBUGP("CBI IRQ data showed reserved bType 0x%x\n",
                        us->iobuf[0]);
            goto Failed;

      }

      /* The second byte & 0x0F should be 0x0 for good, otherwise error */
      switch (us->iobuf[1] & 0x0F) {
            case 0x00: 
                  return USB_STOR_TRANSPORT_GOOD;
            case 0x01: 
                  goto Failed;
      }
      return USB_STOR_TRANSPORT_ERROR;

      /* the CBI spec requires that the bulk pipe must be cleared
       * following any data-in/out command failure (section 2.4.3.1.3)
       */
  Failed:
      if (pipe)
            usb_stor_clear_halt(us, pipe);
      return USB_STOR_TRANSPORT_FAILED;
}

/*
 * Control/Bulk transport
 */
int usb_stor_CB_transport(struct scsi_cmnd *srb, struct us_data *us)
{
      unsigned int transfer_length = srb->request_bufflen;
      int result;

      /* COMMAND STAGE */
      /* let's send the command via the control pipe */
      result = usb_stor_ctrl_transfer(us, us->send_ctrl_pipe,
                              US_CBI_ADSC, 
                              USB_TYPE_CLASS | USB_RECIP_INTERFACE, 0, 
                              us->ifnum, srb->cmnd, srb->cmd_len);

      /* check the return code for the command */
      US_DEBUGP("Call to usb_stor_ctrl_transfer() returned %d\n", result);

      /* if we stalled the command, it means command failed */
      if (result == USB_STOR_XFER_STALLED) {
            return USB_STOR_TRANSPORT_FAILED;
      }

      /* Uh oh... serious problem here */
      if (result != USB_STOR_XFER_GOOD) {
            return USB_STOR_TRANSPORT_ERROR;
      }

      /* DATA STAGE */
      /* transfer the data payload for this command, if one exists*/
      if (transfer_length) {
            unsigned int pipe = srb->sc_data_direction == DMA_FROM_DEVICE ? 
                        us->recv_bulk_pipe : us->send_bulk_pipe;
            result = usb_stor_bulk_transfer_sg(us, pipe,
                              srb->request_buffer, transfer_length,
                              srb->use_sg, &srb->resid);
            US_DEBUGP("CB data stage result is 0x%x\n", result);

            /* if we stalled the data transfer it means command failed */
            if (result == USB_STOR_XFER_STALLED)
                  return USB_STOR_TRANSPORT_FAILED;
            if (result > USB_STOR_XFER_STALLED)
                  return USB_STOR_TRANSPORT_ERROR;
      }

      /* STATUS STAGE */
      /* NOTE: CB does not have a status stage.  Silly, I know.  So
       * we have to catch this at a higher level.
       */
      return USB_STOR_TRANSPORT_GOOD;
}

/*
 * Bulk only transport
 */

/* Determine what the maximum LUN supported is */
int usb_stor_Bulk_max_lun(struct us_data *us)
{
      int result;

      /* issue the command */
      us->iobuf[0] = 0;
      result = usb_stor_control_msg(us, us->recv_ctrl_pipe,
                         US_BULK_GET_MAX_LUN, 
                         USB_DIR_IN | USB_TYPE_CLASS | 
                         USB_RECIP_INTERFACE,
                         0, us->ifnum, us->iobuf, 1, HZ);

      US_DEBUGP("GetMaxLUN command result is %d, data is %d\n", 
              result, us->iobuf[0]);

      /* if we have a successful request, return the result */
      if (result > 0)
            return us->iobuf[0];

      /* 
       * Some devices (i.e. Iomega Zip100) need this -- apparently
       * the bulk pipes get STALLed when the GetMaxLUN request is
       * processed.   This is, in theory, harmless to all other devices
       * (regardless of if they stall or not).
       */
      if (result == -EPIPE) {
            usb_stor_clear_halt(us, us->recv_bulk_pipe);
            usb_stor_clear_halt(us, us->send_bulk_pipe);
      }

      /*
       * Some devices don't like GetMaxLUN.  They may STALL the control
       * pipe, they may return a zero-length result, they may do nothing at
       * all and timeout, or they may fail in even more bizarrely creative
       * ways.  In these cases the best approach is to use the default
       * value: only one LUN.
       */
      return 0;
}

int usb_stor_Bulk_transport(struct scsi_cmnd *srb, struct us_data *us)
{
      struct bulk_cb_wrap *bcb = (struct bulk_cb_wrap *) us->iobuf;
      struct bulk_cs_wrap *bcs = (struct bulk_cs_wrap *) us->iobuf;
      unsigned int transfer_length = srb->request_bufflen;
      unsigned int residue;
      int result;
      int fake_sense = 0;
      unsigned int cswlen;
      unsigned int cbwlen = US_BULK_CB_WRAP_LEN;

      /* Take care of BULK32 devices; set extra byte to 0 */
      if ( unlikely(us->flags & US_FL_BULK32)) {
            cbwlen = 32;
            us->iobuf[31] = 0;
      }

      /* set up the command wrapper */
      bcb->Signature = cpu_to_le32(US_BULK_CB_SIGN);
      bcb->DataTransferLength = cpu_to_le32(transfer_length);
      bcb->Flags = srb->sc_data_direction == DMA_FROM_DEVICE ? 1 << 7 : 0;
      bcb->Tag = ++us->tag;
      bcb->Lun = srb->device->lun;
      if (us->flags & US_FL_SCM_MULT_TARG)
            bcb->Lun |= srb->device->id << 4;
      bcb->Length = srb->cmd_len;

      /* copy the command payload */
      memset(bcb->CDB, 0, sizeof(bcb->CDB));
      memcpy(bcb->CDB, srb->cmnd, bcb->Length);

      /* send it to out endpoint */
      US_DEBUGP("Bulk Command S 0x%x T 0x%x L %d F %d Trg %d LUN %d CL %d\n",
                  le32_to_cpu(bcb->Signature), bcb->Tag,
                  le32_to_cpu(bcb->DataTransferLength), bcb->Flags,
                  (bcb->Lun >> 4), (bcb->Lun & 0x0F), 
                  bcb->Length);
      result = usb_stor_bulk_transfer_buf(us, us->send_bulk_pipe,
                        bcb, cbwlen, NULL);
      US_DEBUGP("Bulk command transfer result=%d\n", result);
      if (result != USB_STOR_XFER_GOOD)
            return USB_STOR_TRANSPORT_ERROR;

      /* DATA STAGE */
      /* send/receive data payload, if there is any */

      /* Some USB-IDE converter chips need a 100us delay between the
       * command phase and the data phase.  Some devices need a little
       * more than that, probably because of clock rate inaccuracies. */
      if (unlikely(us->flags & US_FL_GO_SLOW))
            udelay(125);

      if (transfer_length) {
            unsigned int pipe = srb->sc_data_direction == DMA_FROM_DEVICE ? 
                        us->recv_bulk_pipe : us->send_bulk_pipe;
            result = usb_stor_bulk_transfer_sg(us, pipe,
                              srb->request_buffer, transfer_length,
                              srb->use_sg, &srb->resid);
            US_DEBUGP("Bulk data transfer result 0x%x\n", result);
            if (result == USB_STOR_XFER_ERROR)
                  return USB_STOR_TRANSPORT_ERROR;

            /* If the device tried to send back more data than the
             * amount requested, the spec requires us to transfer
             * the CSW anyway.  Since there's no point retrying the
             * the command, we'll return fake sense data indicating
             * Illegal Request, Invalid Field in CDB.
             */
            if (result == USB_STOR_XFER_LONG)
                  fake_sense = 1;
      }

      /* See flow chart on pg 15 of the Bulk Only Transport spec for
       * an explanation of how this code works.
       */

      /* get CSW for device status */
      US_DEBUGP("Attempting to get CSW...\n");
      result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
                        bcs, US_BULK_CS_WRAP_LEN, &cswlen);

      /* Some broken devices add unnecessary zero-length packets to the
       * end of their data transfers.  Such packets show up as 0-length
       * CSWs.  If we encounter such a thing, try to read the CSW again.
       */
      if (result == USB_STOR_XFER_SHORT && cswlen == 0) {
            US_DEBUGP("Received 0-length CSW; retrying...\n");
            result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
                        bcs, US_BULK_CS_WRAP_LEN, &cswlen);
      }

      /* did the attempt to read the CSW fail? */
      if (result == USB_STOR_XFER_STALLED) {

            /* get the status again */
            US_DEBUGP("Attempting to get CSW (2nd try)...\n");
            result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
                        bcs, US_BULK_CS_WRAP_LEN, NULL);
      }

      /* if we still have a failure at this point, we're in trouble */
      US_DEBUGP("Bulk status result = %d\n", result);
      if (result != USB_STOR_XFER_GOOD)
            return USB_STOR_TRANSPORT_ERROR;

      /* check bulk status */
      residue = le32_to_cpu(bcs->Residue);
      US_DEBUGP("Bulk Status S 0x%x T 0x%x R %u Stat 0x%x\n",
                  le32_to_cpu(bcs->Signature), bcs->Tag, 
                  residue, bcs->Status);
      if (bcs->Tag != us->tag || bcs->Status > US_BULK_STAT_PHASE) {
            US_DEBUGP("Bulk logical error\n");
            return USB_STOR_TRANSPORT_ERROR;
      }

      /* Some broken devices report odd signatures, so we do not check them
       * for validity against the spec. We store the first one we see,
       * and check subsequent transfers for validity against this signature.
       */
      if (!us->bcs_signature) {
            us->bcs_signature = bcs->Signature;
            if (us->bcs_signature != cpu_to_le32(US_BULK_CS_SIGN))
                  US_DEBUGP("Learnt BCS signature 0x%08X\n",
                              le32_to_cpu(us->bcs_signature));
      } else if (bcs->Signature != us->bcs_signature) {
            US_DEBUGP("Signature mismatch: got %08X, expecting %08X\n",
                    le32_to_cpu(bcs->Signature),
                    le32_to_cpu(us->bcs_signature));
            return USB_STOR_TRANSPORT_ERROR;
      }

      /* try to compute the actual residue, based on how much data
       * was really transferred and what the device tells us */
      if (residue) {
            if (!(us->flags & US_FL_IGNORE_RESIDUE)) {
                  residue = min(residue, transfer_length);
                  srb->resid = max(srb->resid, (int) residue);
            }
      }

      /* based on the status code, we report good or bad */
      switch (bcs->Status) {
            case US_BULK_STAT_OK:
                  /* device babbled -- return fake sense data */
                  if (fake_sense) {
                        memcpy(srb->sense_buffer, 
                               usb_stor_sense_invalidCDB, 
                               sizeof(usb_stor_sense_invalidCDB));
                        return USB_STOR_TRANSPORT_NO_SENSE;
                  }

                  /* command good -- note that data could be short */
                  return USB_STOR_TRANSPORT_GOOD;

            case US_BULK_STAT_FAIL:
                  /* command failed */
                  return USB_STOR_TRANSPORT_FAILED;

            case US_BULK_STAT_PHASE:
                  /* phase error -- note that a transport reset will be
                   * invoked by the invoke_transport() function
                   */
                  return USB_STOR_TRANSPORT_ERROR;
      }

      /* we should never get here, but if we do, we're in trouble */
      return USB_STOR_TRANSPORT_ERROR;
}

/***********************************************************************
 * Reset routines
 ***********************************************************************/

/* This is the common part of the device reset code.
 *
 * It's handy that every transport mechanism uses the control endpoint for
 * resets.
 *
 * Basically, we send a reset with a 5-second timeout, so we don't get
 * jammed attempting to do the reset.
 */
static int usb_stor_reset_common(struct us_data *us,
            u8 request, u8 requesttype,
            u16 value, u16 index, void *data, u16 size)
{
      int result;
      int result2;

      if (test_bit(US_FLIDX_DISCONNECTING, &us->flags)) {
            US_DEBUGP("No reset during disconnect\n");
            return -EIO;
      }

      result = usb_stor_control_msg(us, us->send_ctrl_pipe,
                  request, requesttype, value, index, data, size,
                  5*HZ);
      if (result < 0) {
            US_DEBUGP("Soft reset failed: %d\n", result);
            return result;
      }

      /* Give the device some time to recover from the reset,
       * but don't delay disconnect processing. */
      wait_event_interruptible_timeout(us->delay_wait,
                  test_bit(US_FLIDX_DISCONNECTING, &us->flags),
                  HZ*6);
      if (test_bit(US_FLIDX_DISCONNECTING, &us->flags)) {
            US_DEBUGP("Reset interrupted by disconnect\n");
            return -EIO;
      }

      US_DEBUGP("Soft reset: clearing bulk-in endpoint halt\n");
      result = usb_stor_clear_halt(us, us->recv_bulk_pipe);

      US_DEBUGP("Soft reset: clearing bulk-out endpoint halt\n");
      result2 = usb_stor_clear_halt(us, us->send_bulk_pipe);

      /* return a result code based on the result of the clear-halts */
      if (result >= 0)
            result = result2;
      if (result < 0)
            US_DEBUGP("Soft reset failed\n");
      else
            US_DEBUGP("Soft reset done\n");
      return result;
}

/* This issues a CB[I] Reset to the device in question
 */
#define CB_RESET_CMD_SIZE     12

int usb_stor_CB_reset(struct us_data *us)
{
      US_DEBUGP("%s called\n", __FUNCTION__);

      memset(us->iobuf, 0xFF, CB_RESET_CMD_SIZE);
      us->iobuf[0] = SEND_DIAGNOSTIC;
      us->iobuf[1] = 4;
      return usb_stor_reset_common(us, US_CBI_ADSC, 
                         USB_TYPE_CLASS | USB_RECIP_INTERFACE,
                         0, us->ifnum, us->iobuf, CB_RESET_CMD_SIZE);
}

/* This issues a Bulk-only Reset to the device in question, including
 * clearing the subsequent endpoint halts that may occur.
 */
int usb_stor_Bulk_reset(struct us_data *us)
{
      US_DEBUGP("%s called\n", __FUNCTION__);

      return usb_stor_reset_common(us, US_BULK_RESET_REQUEST, 
                         USB_TYPE_CLASS | USB_RECIP_INTERFACE,
                         0, us->ifnum, NULL, 0);
}

/* Issue a USB port reset to the device.  The caller must not hold
 * us->dev_mutex.
 */
int usb_stor_port_reset(struct us_data *us)
{
      int result, rc_lock;

      result = rc_lock =
            usb_lock_device_for_reset(us->pusb_dev, us->pusb_intf);
      if (result < 0)
            US_DEBUGP("unable to lock device for reset: %d\n", result);
      else {
            /* Were we disconnected while waiting for the lock? */
            if (test_bit(US_FLIDX_DISCONNECTING, &us->flags)) {
                  result = -EIO;
                  US_DEBUGP("No reset during disconnect\n");
            } else {
                  result = usb_reset_composite_device(
                              us->pusb_dev, us->pusb_intf);
                  US_DEBUGP("usb_reset_composite_device returns %d\n",
                              result);
            }
            if (rc_lock)
                  usb_unlock_device(us->pusb_dev);
      }
      return result;
}

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