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// SPDX-License-Identifier: GPL-2.0+
/*
* Driver for USB Mass Storage compliant devices
*
* 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) 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.
*/
#include <linux/highmem.h>
#include <linux/export.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include "usb.h"
#include "protocol.h"
#include "debug.h"
#include "scsiglue.h"
#include "transport.h"
/***********************************************************************
* Protocol routines
***********************************************************************/
void usb_stor_pad12_command(struct scsi_cmnd *srb, struct us_data *us)
{
/*
* Pad the SCSI command with zeros out to 12 bytes. If the
* command already is 12 bytes or longer, leave it alone.
*
* NOTE: This only works because a scsi_cmnd struct field contains
* a unsigned char cmnd[16], so we know we have storage available
*/
for (; srb->cmd_len < 12; srb->cmd_len++)
srb->cmnd[srb->cmd_len] = 0;
/* send the command to the transport layer */
usb_stor_invoke_transport(srb, us);
}
void usb_stor_ufi_command(struct scsi_cmnd *srb, struct us_data *us)
{
/*
* fix some commands -- this is a form of mode translation
* UFI devices only accept 12 byte long commands
*
* NOTE: This only works because a scsi_cmnd struct field contains
* a unsigned char cmnd[16], so we know we have storage available
*/
/* Pad the ATAPI command with zeros */
for (; srb->cmd_len < 12; srb->cmd_len++)
srb->cmnd[srb->cmd_len] = 0;
/* set command length to 12 bytes (this affects the transport layer) */
srb->cmd_len = 12;
/* XXX We should be constantly re-evaluating the need for these */
/* determine the correct data length for these commands */
switch (srb->cmnd[0]) {
/* for INQUIRY, UFI devices only ever return 36 bytes */
case INQUIRY:
srb->cmnd[4] = 36;
break;
/* again, for MODE_SENSE_10, we get the minimum (8) */
case MODE_SENSE_10:
srb->cmnd[7] = 0;
srb->cmnd[8] = 8;
break;
/* for REQUEST_SENSE, UFI devices only ever return 18 bytes */
case REQUEST_SENSE:
srb->cmnd[4] = 18;
break;
} /* end switch on cmnd[0] */
/* send the command to the transport layer */
usb_stor_invoke_transport(srb, us);
}
void usb_stor_transparent_scsi_command(struct scsi_cmnd *srb,
struct us_data *us)
{
/* send the command to the transport layer */
usb_stor_invoke_transport(srb, us);
}
EXPORT_SYMBOL_GPL(usb_stor_transparent_scsi_command);
/***********************************************************************
* Scatter-gather transfer buffer access routines
***********************************************************************/
/*
* Copy a buffer of length buflen to/from the srb's transfer buffer.
* Update the **sgptr and *offset variables so that the next copy will
* pick up from where this one left off.
*/
unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
unsigned int buflen, struct scsi_cmnd *srb, struct scatterlist **sgptr,
unsigned int *offset, enum xfer_buf_dir dir)
{
unsigned int cnt = 0;
struct scatterlist *sg = *sgptr;
struct sg_mapping_iter miter;
unsigned int nents = scsi_sg_count(srb);
if (sg)
nents = sg_nents(sg);
else
sg = scsi_sglist(srb);
sg_miter_start(&miter, sg, nents, dir == FROM_XFER_BUF ?
SG_MITER_FROM_SG: SG_MITER_TO_SG);
if (!sg_miter_skip(&miter, *offset))
return cnt;
while (sg_miter_next(&miter) && cnt < buflen) {
unsigned int len = min_t(unsigned int, miter.length,
buflen - cnt);
if (dir == FROM_XFER_BUF)
memcpy(buffer + cnt, miter.addr, len);
else
memcpy(miter.addr, buffer + cnt, len);
if (*offset + len < miter.piter.sg->length) {
*offset += len;
*sgptr = miter.piter.sg;
} else {
*offset = 0;
*sgptr = sg_next(miter.piter.sg);
}
cnt += len;
}
sg_miter_stop(&miter);
return cnt;
}
EXPORT_SYMBOL_GPL(usb_stor_access_xfer_buf);
/*
* Store the contents of buffer into srb's transfer buffer and set the
* SCSI residue.
*/
void usb_stor_set_xfer_buf(unsigned char *buffer,
unsigned int buflen, struct scsi_cmnd *srb)
{
unsigned int offset = 0;
struct scatterlist *sg = NULL;
buflen = min(buflen, scsi_bufflen(srb));
buflen = usb_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset,
TO_XFER_BUF);
if (buflen < scsi_bufflen(srb))
scsi_set_resid(srb, scsi_bufflen(srb) - buflen);
}
EXPORT_SYMBOL_GPL(usb_stor_set_xfer_buf);
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