// 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);