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 <linux/export.h> 47 #include <scsi/scsi.h> 48 #include <scsi/scsi_cmnd.h> 49 50 #include "usb.h" 51 #include "protocol.h" 52 #include "debug.h" 53 #include "scsiglue.h" 54 #include "transport.h" 55 56 /*********************************************************************** 57 * Protocol routines 58 ***********************************************************************/ 59 60 void usb_stor_pad12_command(struct scsi_cmnd *srb, struct us_data *us) 61 { 62 /* Pad the SCSI command with zeros out to 12 bytes 63 * 64 * NOTE: This only works because a scsi_cmnd struct field contains 65 * a unsigned char cmnd[16], so we know we have storage available 66 */ 67 for (; srb->cmd_len<12; srb->cmd_len++) 68 srb->cmnd[srb->cmd_len] = 0; 69 70 /* set command length to 12 bytes */ 71 srb->cmd_len = 12; 72 73 /* send the command to the transport layer */ 74 usb_stor_invoke_transport(srb, us); 75 } 76 77 void usb_stor_ufi_command(struct scsi_cmnd *srb, struct us_data *us) 78 { 79 /* fix some commands -- this is a form of mode translation 80 * UFI devices only accept 12 byte long commands 81 * 82 * NOTE: This only works because a scsi_cmnd struct field contains 83 * a unsigned char cmnd[16], so we know we have storage available 84 */ 85 86 /* Pad the ATAPI command with zeros */ 87 for (; srb->cmd_len<12; srb->cmd_len++) 88 srb->cmnd[srb->cmd_len] = 0; 89 90 /* set command length to 12 bytes (this affects the transport layer) */ 91 srb->cmd_len = 12; 92 93 /* XXX We should be constantly re-evaluating the need for these */ 94 95 /* determine the correct data length for these commands */ 96 switch (srb->cmnd[0]) { 97 98 /* for INQUIRY, UFI devices only ever return 36 bytes */ 99 case INQUIRY: 100 srb->cmnd[4] = 36; 101 break; 102 103 /* again, for MODE_SENSE_10, we get the minimum (8) */ 104 case MODE_SENSE_10: 105 srb->cmnd[7] = 0; 106 srb->cmnd[8] = 8; 107 break; 108 109 /* for REQUEST_SENSE, UFI devices only ever return 18 bytes */ 110 case REQUEST_SENSE: 111 srb->cmnd[4] = 18; 112 break; 113 } /* end switch on cmnd[0] */ 114 115 /* send the command to the transport layer */ 116 usb_stor_invoke_transport(srb, us); 117 } 118 119 void usb_stor_transparent_scsi_command(struct scsi_cmnd *srb, 120 struct us_data *us) 121 { 122 /* send the command to the transport layer */ 123 usb_stor_invoke_transport(srb, us); 124 } 125 EXPORT_SYMBOL_GPL(usb_stor_transparent_scsi_command); 126 127 /*********************************************************************** 128 * Scatter-gather transfer buffer access routines 129 ***********************************************************************/ 130 131 /* Copy a buffer of length buflen to/from the srb's transfer buffer. 132 * Update the **sgptr and *offset variables so that the next copy will 133 * pick up from where this one left off. 134 */ 135 unsigned int usb_stor_access_xfer_buf(unsigned char *buffer, 136 unsigned int buflen, struct scsi_cmnd *srb, struct scatterlist **sgptr, 137 unsigned int *offset, enum xfer_buf_dir dir) 138 { 139 unsigned int cnt; 140 struct scatterlist *sg = *sgptr; 141 142 /* We have to go through the list one entry 143 * at a time. Each s-g entry contains some number of pages, and 144 * each page has to be kmap()'ed separately. If the page is already 145 * in kernel-addressable memory then kmap() will return its address. 146 * If the page is not directly accessible -- such as a user buffer 147 * located in high memory -- then kmap() will map it to a temporary 148 * position in the kernel's virtual address space. 149 */ 150 151 if (!sg) 152 sg = scsi_sglist(srb); 153 154 /* This loop handles a single s-g list entry, which may 155 * include multiple pages. Find the initial page structure 156 * and the starting offset within the page, and update 157 * the *offset and **sgptr values for the next loop. 158 */ 159 cnt = 0; 160 while (cnt < buflen && sg) { 161 struct page *page = sg_page(sg) + 162 ((sg->offset + *offset) >> PAGE_SHIFT); 163 unsigned int poff = (sg->offset + *offset) & (PAGE_SIZE-1); 164 unsigned int sglen = sg->length - *offset; 165 166 if (sglen > buflen - cnt) { 167 168 /* Transfer ends within this s-g entry */ 169 sglen = buflen - cnt; 170 *offset += sglen; 171 } else { 172 173 /* Transfer continues to next s-g entry */ 174 *offset = 0; 175 sg = sg_next(sg); 176 } 177 178 /* Transfer the data for all the pages in this 179 * s-g entry. For each page: call kmap(), do the 180 * transfer, and call kunmap() immediately after. */ 181 while (sglen > 0) { 182 unsigned int plen = min(sglen, (unsigned int) 183 PAGE_SIZE - poff); 184 unsigned char *ptr = kmap(page); 185 186 if (dir == TO_XFER_BUF) 187 memcpy(ptr + poff, buffer + cnt, plen); 188 else 189 memcpy(buffer + cnt, ptr + poff, plen); 190 kunmap(page); 191 192 /* Start at the beginning of the next page */ 193 poff = 0; 194 ++page; 195 cnt += plen; 196 sglen -= plen; 197 } 198 } 199 *sgptr = sg; 200 201 /* Return the amount actually transferred */ 202 return cnt; 203 } 204 EXPORT_SYMBOL_GPL(usb_stor_access_xfer_buf); 205 206 /* Store the contents of buffer into srb's transfer buffer and set the 207 * SCSI residue. 208 */ 209 void usb_stor_set_xfer_buf(unsigned char *buffer, 210 unsigned int buflen, struct scsi_cmnd *srb) 211 { 212 unsigned int offset = 0; 213 struct scatterlist *sg = NULL; 214 215 buflen = min(buflen, scsi_bufflen(srb)); 216 buflen = usb_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset, 217 TO_XFER_BUF); 218 if (buflen < scsi_bufflen(srb)) 219 scsi_set_resid(srb, scsi_bufflen(srb) - buflen); 220 } 221 EXPORT_SYMBOL_GPL(usb_stor_set_xfer_buf); 222