1/* Driver for USB Mass Storage compliant devices 2 * 3 * Current development and maintenance by: 4 * (c) 1999-2002 Matthew Dharm (mdharm-usb@one-eyed-alien.net) 5 * 6 * Developed with the assistance of: 7 * (c) 2000 David L. Brown, Jr. (usb-storage@davidb.org) 8 * (c) 2002 Alan Stern (stern@rowland.org) 9 * 10 * Initial work by: 11 * (c) 1999 Michael Gee (michael@linuxspecific.com) 12 * 13 * This driver is based on the 'USB Mass Storage Class' document. This 14 * describes in detail the protocol used to communicate with such 15 * devices. Clearly, the designers had SCSI and ATAPI commands in 16 * mind when they created this document. The commands are all very 17 * similar to commands in the SCSI-II and ATAPI specifications. 18 * 19 * It is important to note that in a number of cases this class 20 * exhibits class-specific exemptions from the USB specification. 21 * Notably the usage of NAK, STALL and ACK differs from the norm, in 22 * that they are used to communicate wait, failed and OK on commands. 23 * 24 * Also, for certain devices, the interrupt endpoint is used to convey 25 * status of a command. 26 * 27 * Please see http://www.one-eyed-alien.net/~mdharm/linux-usb for more 28 * information about this driver. 29 * 30 * This program is free software; you can redistribute it and/or modify it 31 * under the terms of the GNU General Public License as published by the 32 * Free Software Foundation; either version 2, or (at your option) any 33 * later version. 34 * 35 * This program is distributed in the hope that it will be useful, but 36 * WITHOUT ANY WARRANTY; without even the implied warranty of 37 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 38 * General Public License for more details. 39 * 40 * You should have received a copy of the GNU General Public License along 41 * with this program; if not, write to the Free Software Foundation, Inc., 42 * 675 Mass Ave, Cambridge, MA 02139, USA. 43 */ 44 45#include <linux/highmem.h> 46#include <scsi/scsi.h> 47#include <scsi/scsi_cmnd.h> 48 49#include "usb.h" 50#include "protocol.h" 51#include "debug.h" 52#include "scsiglue.h" 53#include "transport.h" 54 55/*********************************************************************** 56 * Protocol routines 57 ***********************************************************************/ 58 59void usb_stor_pad12_command(struct scsi_cmnd *srb, struct us_data *us) 60{ 61 /* Pad the SCSI command with zeros out to 12 bytes 62 * 63 * NOTE: This only works because a scsi_cmnd struct field contains 64 * a unsigned char cmnd[16], so we know we have storage available 65 */ 66 for (; srb->cmd_len<12; srb->cmd_len++) 67 srb->cmnd[srb->cmd_len] = 0; 68 69 /* set command length to 12 bytes */ 70 srb->cmd_len = 12; 71 72 /* send the command to the transport layer */ 73 usb_stor_invoke_transport(srb, us); 74} 75 76void usb_stor_ufi_command(struct scsi_cmnd *srb, struct us_data *us) 77{ 78 /* fix some commands -- this is a form of mode translation 79 * UFI devices only accept 12 byte long commands 80 * 81 * NOTE: This only works because a scsi_cmnd struct field contains 82 * a unsigned char cmnd[16], so we know we have storage available 83 */ 84 85 /* Pad the ATAPI command with zeros */ 86 for (; srb->cmd_len<12; srb->cmd_len++) 87 srb->cmnd[srb->cmd_len] = 0; 88 89 /* set command length to 12 bytes (this affects the transport layer) */ 90 srb->cmd_len = 12; 91 92 93 /* determine the correct data length for these commands */ 94 switch (srb->cmnd[0]) { 95 96 /* for INQUIRY, UFI devices only ever return 36 bytes */ 97 case INQUIRY: 98 srb->cmnd[4] = 36; 99 break; 100 101 /* again, for MODE_SENSE_10, we get the minimum (8) */ 102 case MODE_SENSE_10: 103 srb->cmnd[7] = 0; 104 srb->cmnd[8] = 8; 105 break; 106 107 /* for REQUEST_SENSE, UFI devices only ever return 18 bytes */ 108 case REQUEST_SENSE: 109 srb->cmnd[4] = 18; 110 break; 111 } /* end switch on cmnd[0] */ 112 113 /* send the command to the transport layer */ 114 usb_stor_invoke_transport(srb, us); 115} 116 117void usb_stor_transparent_scsi_command(struct scsi_cmnd *srb, 118 struct us_data *us) 119{ 120 /* send the command to the transport layer */ 121 usb_stor_invoke_transport(srb, us); 122} 123EXPORT_SYMBOL_GPL(usb_stor_transparent_scsi_command); 124 125/*********************************************************************** 126 * Scatter-gather transfer buffer access routines 127 ***********************************************************************/ 128 129/* Copy a buffer of length buflen to/from the srb's transfer buffer. 130 * Update the **sgptr and *offset variables so that the next copy will 131 * pick up from where this one left off. 132 */ 133unsigned int usb_stor_access_xfer_buf(unsigned char *buffer, 134 unsigned int buflen, struct scsi_cmnd *srb, struct scatterlist **sgptr, 135 unsigned int *offset, enum xfer_buf_dir dir) 136{ 137 unsigned int cnt; 138 struct scatterlist *sg = *sgptr; 139 140 /* We have to go through the list one entry 141 * at a time. Each s-g entry contains some number of pages, and 142 * each page has to be kmap()'ed separately. If the page is already 143 * in kernel-addressable memory then kmap() will return its address. 144 * If the page is not directly accessible -- such as a user buffer 145 * located in high memory -- then kmap() will map it to a temporary 146 * position in the kernel's virtual address space. 147 */ 148 149 if (!sg) 150 sg = scsi_sglist(srb); 151 152 /* This loop handles a single s-g list entry, which may 153 * include multiple pages. Find the initial page structure 154 * and the starting offset within the page, and update 155 * the *offset and **sgptr values for the next loop. 156 */ 157 cnt = 0; 158 while (cnt < buflen && sg) { 159 struct page *page = sg_page(sg) + 160 ((sg->offset + *offset) >> PAGE_SHIFT); 161 unsigned int poff = (sg->offset + *offset) & (PAGE_SIZE-1); 162 unsigned int sglen = sg->length - *offset; 163 164 if (sglen > buflen - cnt) { 165 166 /* Transfer ends within this s-g entry */ 167 sglen = buflen - cnt; 168 *offset += sglen; 169 } else { 170 171 /* Transfer continues to next s-g entry */ 172 *offset = 0; 173 sg = sg_next(sg); 174 } 175 176 /* Transfer the data for all the pages in this 177 * s-g entry. For each page: call kmap(), do the 178 * transfer, and call kunmap() immediately after. */ 179 while (sglen > 0) { 180 unsigned int plen = min(sglen, (unsigned int) 181 PAGE_SIZE - poff); 182 unsigned char *ptr = kmap(page); 183 184 if (dir == TO_XFER_BUF) 185 memcpy(ptr + poff, buffer + cnt, plen); 186 else 187 memcpy(buffer + cnt, ptr + poff, plen); 188 kunmap(page); 189 190 /* Start at the beginning of the next page */ 191 poff = 0; 192 ++page; 193 cnt += plen; 194 sglen -= plen; 195 } 196 } 197 *sgptr = sg; 198 199 /* Return the amount actually transferred */ 200 return cnt; 201} 202EXPORT_SYMBOL_GPL(usb_stor_access_xfer_buf); 203 204/* Store the contents of buffer into srb's transfer buffer and set the 205 * SCSI residue. 206 */ 207void usb_stor_set_xfer_buf(unsigned char *buffer, 208 unsigned int buflen, struct scsi_cmnd *srb) 209{ 210 unsigned int offset = 0; 211 struct scatterlist *sg = NULL; 212 213 buflen = min(buflen, scsi_bufflen(srb)); 214 buflen = usb_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset, 215 TO_XFER_BUF); 216 if (buflen < scsi_bufflen(srb)) 217 scsi_set_resid(srb, scsi_bufflen(srb) - buflen); 218} 219EXPORT_SYMBOL_GPL(usb_stor_set_xfer_buf); 220