221 lines
6.9 KiB
C
221 lines
6.9 KiB
C
/* Driver for USB Mass Storage compliant devices
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*
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* Current development and maintenance by:
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* (c) 1999-2002 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
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*
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* Developed with the assistance of:
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* (c) 2000 David L. Brown, Jr. (usb-storage@davidb.org)
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* (c) 2002 Alan Stern (stern@rowland.org)
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*
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* Initial work by:
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* (c) 1999 Michael Gee (michael@linuxspecific.com)
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*
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* This driver is based on the 'USB Mass Storage Class' document. This
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* describes in detail the protocol used to communicate with such
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* devices. Clearly, the designers had SCSI and ATAPI commands in
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* mind when they created this document. The commands are all very
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* similar to commands in the SCSI-II and ATAPI specifications.
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*
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* It is important to note that in a number of cases this class
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* exhibits class-specific exemptions from the USB specification.
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* Notably the usage of NAK, STALL and ACK differs from the norm, in
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* that they are used to communicate wait, failed and OK on commands.
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*
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* Also, for certain devices, the interrupt endpoint is used to convey
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* status of a command.
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*
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* Please see http://www.one-eyed-alien.net/~mdharm/linux-usb for more
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* information about this driver.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2, or (at your option) any
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* later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/highmem.h>
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#include <scsi/scsi.h>
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#include <scsi/scsi_cmnd.h>
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#include "usb.h"
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#include "protocol.h"
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#include "debug.h"
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#include "scsiglue.h"
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#include "transport.h"
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/***********************************************************************
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* Protocol routines
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***********************************************************************/
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void usb_stor_pad12_command(struct scsi_cmnd *srb, struct us_data *us)
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{
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/* Pad the SCSI command with zeros out to 12 bytes
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*
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* NOTE: This only works because a scsi_cmnd struct field contains
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* a unsigned char cmnd[16], so we know we have storage available
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*/
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for (; srb->cmd_len<12; srb->cmd_len++)
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srb->cmnd[srb->cmd_len] = 0;
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/* set command length to 12 bytes */
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srb->cmd_len = 12;
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/* send the command to the transport layer */
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usb_stor_invoke_transport(srb, us);
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}
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void usb_stor_ufi_command(struct scsi_cmnd *srb, struct us_data *us)
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{
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/* fix some commands -- this is a form of mode translation
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* UFI devices only accept 12 byte long commands
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*
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* NOTE: This only works because a scsi_cmnd struct field contains
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* a unsigned char cmnd[16], so we know we have storage available
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*/
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/* Pad the ATAPI command with zeros */
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for (; srb->cmd_len<12; srb->cmd_len++)
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srb->cmnd[srb->cmd_len] = 0;
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/* set command length to 12 bytes (this affects the transport layer) */
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srb->cmd_len = 12;
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/* XXX We should be constantly re-evaluating the need for these */
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/* determine the correct data length for these commands */
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switch (srb->cmnd[0]) {
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/* for INQUIRY, UFI devices only ever return 36 bytes */
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case INQUIRY:
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srb->cmnd[4] = 36;
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break;
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/* again, for MODE_SENSE_10, we get the minimum (8) */
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case MODE_SENSE_10:
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srb->cmnd[7] = 0;
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srb->cmnd[8] = 8;
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break;
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/* for REQUEST_SENSE, UFI devices only ever return 18 bytes */
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case REQUEST_SENSE:
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srb->cmnd[4] = 18;
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break;
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} /* end switch on cmnd[0] */
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/* send the command to the transport layer */
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usb_stor_invoke_transport(srb, us);
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}
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void usb_stor_transparent_scsi_command(struct scsi_cmnd *srb,
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struct us_data *us)
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{
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/* send the command to the transport layer */
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usb_stor_invoke_transport(srb, us);
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}
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EXPORT_SYMBOL_GPL(usb_stor_transparent_scsi_command);
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/***********************************************************************
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* Scatter-gather transfer buffer access routines
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***********************************************************************/
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/* Copy a buffer of length buflen to/from the srb's transfer buffer.
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* Update the **sgptr and *offset variables so that the next copy will
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* pick up from where this one left off.
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*/
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unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
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unsigned int buflen, struct scsi_cmnd *srb, struct scatterlist **sgptr,
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unsigned int *offset, enum xfer_buf_dir dir)
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{
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unsigned int cnt;
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struct scatterlist *sg = *sgptr;
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/* We have to go through the list one entry
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* at a time. Each s-g entry contains some number of pages, and
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* each page has to be kmap()'ed separately. If the page is already
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* in kernel-addressable memory then kmap() will return its address.
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* If the page is not directly accessible -- such as a user buffer
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* located in high memory -- then kmap() will map it to a temporary
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* position in the kernel's virtual address space.
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*/
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if (!sg)
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sg = scsi_sglist(srb);
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/* This loop handles a single s-g list entry, which may
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* include multiple pages. Find the initial page structure
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* and the starting offset within the page, and update
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* the *offset and **sgptr values for the next loop.
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*/
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cnt = 0;
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while (cnt < buflen && sg) {
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struct page *page = sg_page(sg) +
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((sg->offset + *offset) >> PAGE_SHIFT);
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unsigned int poff = (sg->offset + *offset) & (PAGE_SIZE-1);
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unsigned int sglen = sg->length - *offset;
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if (sglen > buflen - cnt) {
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/* Transfer ends within this s-g entry */
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sglen = buflen - cnt;
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*offset += sglen;
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} else {
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/* Transfer continues to next s-g entry */
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*offset = 0;
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sg = sg_next(sg);
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}
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/* Transfer the data for all the pages in this
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* s-g entry. For each page: call kmap(), do the
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* transfer, and call kunmap() immediately after. */
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while (sglen > 0) {
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unsigned int plen = min(sglen, (unsigned int)
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PAGE_SIZE - poff);
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unsigned char *ptr = kmap(page);
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if (dir == TO_XFER_BUF)
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memcpy(ptr + poff, buffer + cnt, plen);
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else
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memcpy(buffer + cnt, ptr + poff, plen);
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kunmap(page);
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/* Start at the beginning of the next page */
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poff = 0;
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++page;
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cnt += plen;
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sglen -= plen;
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}
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}
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*sgptr = sg;
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/* Return the amount actually transferred */
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return cnt;
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}
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EXPORT_SYMBOL_GPL(usb_stor_access_xfer_buf);
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/* Store the contents of buffer into srb's transfer buffer and set the
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* SCSI residue.
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*/
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void usb_stor_set_xfer_buf(unsigned char *buffer,
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unsigned int buflen, struct scsi_cmnd *srb)
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{
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unsigned int offset = 0;
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struct scatterlist *sg = NULL;
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buflen = min(buflen, scsi_bufflen(srb));
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buflen = usb_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset,
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TO_XFER_BUF);
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if (buflen < scsi_bufflen(srb))
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scsi_set_resid(srb, scsi_bufflen(srb) - buflen);
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}
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EXPORT_SYMBOL_GPL(usb_stor_set_xfer_buf);
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