drivers/usb/storage/scsiglue.c - kernel/msm - Gitiles

 /* Driver for USB Mass Storage compliant devices
  * SCSI layer glue code
  *
  * $Id: scsiglue.c,v 1.26 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)
  *
  * 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"

 /***********************************************************************
  * 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);
 	struct usb_host_endpoint *bulk_in_ep;

 	/*
 	 * 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;

 	/* Scatter-gather buffers (all but the last) must have a length
 	 * divisible by the bulk maxpacket size.  Otherwise a data packet
 	 * would end up being short, causing a premature end to the data
 	 * transfer.  We'll use the maxpacket value of the bulk-IN pipe
 	 * to set the SCSI device queue's DMA alignment mask.
 	 */
 	bulk_in_ep = us->pusb_dev->ep_in[usb_pipeendpoint(us->recv_bulk_pipe)];
 	blk_queue_update_dma_alignment(sdev->request_queue,
 			le16_to_cpu(bulk_in_ep->desc.wMaxPacketSize) - 1);
 			/* wMaxPacketSize must be a power of 2 */

 	/*
 	 * 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->flags & (US_FL_MAX_SECTORS_64 | US_FL_MAX_SECTORS_MIN)) {
 		unsigned int max_sectors = 64;

 		if (us->flags & 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);
 	}

 	/* 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) {

 		/* 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->flags & 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->flags & 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->flags & 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;
 	} 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->flags & 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->flags)) {
 		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;
 	up(&(us->sema));

 	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->flags);
 	if (!test_bit(US_FLIDX_RESETTING, &us->flags)) {
 		set_bit(US_FLIDX_ABORTING, &us->flags);
 		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->flags & 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->flags & 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 */
 };
	/* Driver for USB Mass Storage compliant devices
	* SCSI layer glue code
	*
	* $Id: scsiglue.c,v 1.26 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)
	*
	* 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"

	/***********************************************************************
	* 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);
	struct usb_host_endpoint *bulk_in_ep;

	/*
	* 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;

	/* Scatter-gather buffers (all but the last) must have a length
	* divisible by the bulk maxpacket size. Otherwise a data packet
	* would end up being short, causing a premature end to the data
	* transfer. We'll use the maxpacket value of the bulk-IN pipe
	* to set the SCSI device queue's DMA alignment mask.
	*/
	bulk_in_ep = us->pusb_dev->ep_in[usb_pipeendpoint(us->recv_bulk_pipe)];
	blk_queue_update_dma_alignment(sdev->request_queue,
	le16_to_cpu(bulk_in_ep->desc.wMaxPacketSize) - 1);
	/* wMaxPacketSize must be a power of 2 */

	/*
	* 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->flags & (US_FL_MAX_SECTORS_64 \| US_FL_MAX_SECTORS_MIN)) {
	unsigned int max_sectors = 64;

	if (us->flags & 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);
	}

	/* 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) {

	/* 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->flags & 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->flags & 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->flags & 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;
	} 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->flags & 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->flags)) {
	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;
	up(&(us->sema));

	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->flags);
	if (!test_bit(US_FLIDX_RESETTING, &us->flags)) {
	set_bit(US_FLIDX_ABORTING, &us->flags);
	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->flags & 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->flags & 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 */
	};