/* 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 <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;	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;}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);