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/* 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.
*
* 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/highmem.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
*
* 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;
/* set command length to 12 bytes */
srb->cmd_len = 12;
/* 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);
}
/***********************************************************************
* 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;
struct scatterlist *sg = *sgptr;
/* We have to go through the list one entry
* at a time. Each s-g entry contains some number of pages, and
* each page has to be kmap()'ed separately. If the page is already
* in kernel-addressable memory then kmap() will return its address.
* If the page is not directly accessible -- such as a user buffer
* located in high memory -- then kmap() will map it to a temporary
* position in the kernel's virtual address space.
*/
if (!sg)
sg = scsi_sglist(srb);
/* This loop handles a single s-g list entry, which may
* include multiple pages. Find the initial page structure
* and the starting offset within the page, and update
* the *offset and **sgptr values for the next loop.
*/
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);
}
/* Transfer the data for all the pages in this
* s-g entry. For each page: call kmap(), do the
* transfer, and call kunmap() immediately after. */
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.
*/
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);
}
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