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