// SPDX-License-Identifier: GPL-2.0+
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/*
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* 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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#include <linux/highmem.h>
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#include <linux/export.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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/*
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* Pad the SCSI command with zeros out to 12 bytes. If the
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* command already is 12 bytes or longer, leave it alone.
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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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/* 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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/*
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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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/*
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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 = 0;
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struct scatterlist *sg = *sgptr;
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struct sg_mapping_iter miter;
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unsigned int nents = scsi_sg_count(srb);
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if (sg)
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nents = sg_nents(sg);
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else
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sg = scsi_sglist(srb);
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sg_miter_start(&miter, sg, nents, dir == FROM_XFER_BUF ?
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SG_MITER_FROM_SG: SG_MITER_TO_SG);
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if (!sg_miter_skip(&miter, *offset))
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return cnt;
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while (sg_miter_next(&miter) && cnt < buflen) {
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unsigned int len = min_t(unsigned int, miter.length,
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buflen - cnt);
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if (dir == FROM_XFER_BUF)
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memcpy(buffer + cnt, miter.addr, len);
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else
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memcpy(miter.addr, buffer + cnt, len);
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if (*offset + len < miter.piter.sg->length) {
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*offset += len;
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*sgptr = miter.piter.sg;
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} else {
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*offset = 0;
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*sgptr = sg_next(miter.piter.sg);
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}
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cnt += len;
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}
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sg_miter_stop(&miter);
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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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/*
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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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