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
60void usb_stor_pad12_command(struct scsi_cmnd *srb, struct us_data *us)
61{
62	/*
63	 * Pad the SCSI command with zeros out to 12 bytes.  If the
64	 * command already is 12 bytes or longer, leave it alone.
65	 *
66	 * NOTE: This only works because a scsi_cmnd struct field contains
67	 * a unsigned char cmnd[16], so we know we have storage available
68	 */
69	for (; srb->cmd_len < 12; srb->cmd_len++)
70		srb->cmnd[srb->cmd_len] = 0;
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	/* XXX We should be constantly re-evaluating the need for these */
93
94	/* determine the correct data length for these commands */
95	switch (srb->cmnd[0]) {
96
97		/* for INQUIRY, UFI devices only ever return 36 bytes */
98	case INQUIRY:
99		srb->cmnd[4] = 36;
100		break;
101
102		/* again, for MODE_SENSE_10, we get the minimum (8) */
103	case MODE_SENSE_10:
104		srb->cmnd[7] = 0;
105		srb->cmnd[8] = 8;
106		break;
107
108		/* for REQUEST_SENSE, UFI devices only ever return 18 bytes */
109	case REQUEST_SENSE:
110		srb->cmnd[4] = 18;
111		break;
112	} /* end switch on cmnd[0] */
113
114	/* send the command to the transport layer */
115	usb_stor_invoke_transport(srb, us);
116}
117
118void usb_stor_transparent_scsi_command(struct scsi_cmnd *srb,
119				       struct us_data *us)
120{
121	/* send the command to the transport layer */
122	usb_stor_invoke_transport(srb, us);
123}
124EXPORT_SYMBOL_GPL(usb_stor_transparent_scsi_command);
125
126/***********************************************************************
127 * Scatter-gather transfer buffer access routines
128 ***********************************************************************/
129
130/* Copy a buffer of length buflen to/from the srb's transfer buffer.
131 * Update the **sgptr and *offset variables so that the next copy will
132 * pick up from where this one left off.
133 */
134unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
135	unsigned int buflen, struct scsi_cmnd *srb, struct scatterlist **sgptr,
136	unsigned int *offset, enum xfer_buf_dir dir)
137{
138	unsigned int cnt = 0;
139	struct scatterlist *sg = *sgptr;
140	struct sg_mapping_iter miter;
141	unsigned int nents = scsi_sg_count(srb);
142
143	if (sg)
144		nents = sg_nents(sg);
145	else
146		sg = scsi_sglist(srb);
147
148	sg_miter_start(&miter, sg, nents, dir == FROM_XFER_BUF ?
149		SG_MITER_FROM_SG: SG_MITER_TO_SG);
150
151	if (!sg_miter_skip(&miter, *offset))
152		return cnt;
153
154	while (sg_miter_next(&miter) && cnt < buflen) {
155		unsigned int len = min_t(unsigned int, miter.length,
156				buflen - cnt);
157
158		if (dir == FROM_XFER_BUF)
159			memcpy(buffer + cnt, miter.addr, len);
160		else
161			memcpy(miter.addr, buffer + cnt, len);
162
163		if (*offset + len < miter.piter.sg->length) {
164			*offset += len;
165			*sgptr = miter.piter.sg;
166		} else {
167			*offset = 0;
168			*sgptr = sg_next(miter.piter.sg);
169		}
170		cnt += len;
171	}
172	sg_miter_stop(&miter);
173
174	return cnt;
175}
176EXPORT_SYMBOL_GPL(usb_stor_access_xfer_buf);
177
178/* Store the contents of buffer into srb's transfer buffer and set the
179 * SCSI residue.
180 */
181void usb_stor_set_xfer_buf(unsigned char *buffer,
182	unsigned int buflen, struct scsi_cmnd *srb)
183{
184	unsigned int offset = 0;
185	struct scatterlist *sg = NULL;
186
187	buflen = min(buflen, scsi_bufflen(srb));
188	buflen = usb_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset,
189			TO_XFER_BUF);
190	if (buflen < scsi_bufflen(srb))
191		scsi_set_resid(srb, scsi_bufflen(srb) - buflen);
192}
193EXPORT_SYMBOL_GPL(usb_stor_set_xfer_buf);
194