1 /* Driver for USB Mass Storage compliant devices
3 * $Id: protocol.c,v 1.14 2002/04/22 03:39:43 mdharm Exp $
5 * Current development and maintenance by:
6 * (c) 1999-2002 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
8 * Developed with the assistance of:
9 * (c) 2000 David L. Brown, Jr. (usb-storage@davidb.org)
10 * (c) 2002 Alan Stern (stern@rowland.org)
13 * (c) 1999 Michael Gee (michael@linuxspecific.com)
15 * This driver is based on the 'USB Mass Storage Class' document. This
16 * describes in detail the protocol used to communicate with such
17 * devices. Clearly, the designers had SCSI and ATAPI commands in
18 * mind when they created this document. The commands are all very
19 * similar to commands in the SCSI-II and ATAPI specifications.
21 * It is important to note that in a number of cases this class
22 * exhibits class-specific exemptions from the USB specification.
23 * Notably the usage of NAK, STALL and ACK differs from the norm, in
24 * that they are used to communicate wait, failed and OK on commands.
26 * Also, for certain devices, the interrupt endpoint is used to convey
27 * status of a command.
29 * Please see http://www.one-eyed-alien.net/~mdharm/linux-usb for more
30 * information about this driver.
32 * This program is free software; you can redistribute it and/or modify it
33 * under the terms of the GNU General Public License as published by the
34 * Free Software Foundation; either version 2, or (at your option) any
37 * This program is distributed in the hope that it will be useful, but
38 * WITHOUT ANY WARRANTY; without even the implied warranty of
39 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
40 * General Public License for more details.
42 * You should have received a copy of the GNU General Public License along
43 * with this program; if not, write to the Free Software Foundation, Inc.,
44 * 675 Mass Ave, Cambridge, MA 02139, USA.
47 #include <linux/highmem.h>
48 #include <scsi/scsi.h>
49 #include <scsi/scsi_cmnd.h>
54 #include "transport.h"
56 /***********************************************************************
58 ***********************************************************************/
61 * Fix-up the return data from a READ CAPACITY command. My Feiya reader
62 * returns a value that is 1 too large.
64 static void fix_read_capacity(struct scsi_cmnd *srb)
66 unsigned int index, offset;
68 unsigned long capacity;
70 /* verify that it's a READ CAPACITY command */
71 if (srb->cmnd[0] != READ_CAPACITY)
75 if (usb_stor_access_xfer_buf((unsigned char *) &c, 4, srb,
76 &index, &offset, FROM_XFER_BUF) != 4)
79 capacity = be32_to_cpu(c);
80 US_DEBUGP("US: Fixing capacity: from %ld to %ld\n",
81 capacity+1, capacity);
82 c = cpu_to_be32(capacity - 1);
85 usb_stor_access_xfer_buf((unsigned char *) &c, 4, srb,
86 &index, &offset, TO_XFER_BUF);
89 /***********************************************************************
91 ***********************************************************************/
93 void usb_stor_qic157_command(struct scsi_cmnd *srb, struct us_data *us)
95 /* Pad the ATAPI command with zeros
97 * NOTE: This only works because a scsi_cmnd struct field contains
98 * a unsigned char cmnd[16], so we know we have storage available
100 for (; srb->cmd_len<12; srb->cmd_len++)
101 srb->cmnd[srb->cmd_len] = 0;
103 /* set command length to 12 bytes */
106 /* send the command to the transport layer */
107 usb_stor_invoke_transport(srb, us);
110 void usb_stor_ATAPI_command(struct scsi_cmnd *srb, struct us_data *us)
112 /* Pad the ATAPI command with zeros
114 * NOTE: This only works because a scsi_cmnd struct field contains
115 * a unsigned char cmnd[16], so we know we have storage available
118 /* Pad the ATAPI command with zeros */
119 for (; srb->cmd_len<12; srb->cmd_len++)
120 srb->cmnd[srb->cmd_len] = 0;
122 /* set command length to 12 bytes */
125 /* send the command to the transport layer */
126 usb_stor_invoke_transport(srb, us);
130 void usb_stor_ufi_command(struct scsi_cmnd *srb, struct us_data *us)
132 /* fix some commands -- this is a form of mode translation
133 * UFI devices only accept 12 byte long commands
135 * NOTE: This only works because a scsi_cmnd struct field contains
136 * a unsigned char cmnd[16], so we know we have storage available
139 /* Pad the ATAPI command with zeros */
140 for (; srb->cmd_len<12; srb->cmd_len++)
141 srb->cmnd[srb->cmd_len] = 0;
143 /* set command length to 12 bytes (this affects the transport layer) */
146 /* XXX We should be constantly re-evaluating the need for these */
148 /* determine the correct data length for these commands */
149 switch (srb->cmnd[0]) {
151 /* for INQUIRY, UFI devices only ever return 36 bytes */
156 /* again, for MODE_SENSE_10, we get the minimum (8) */
162 /* for REQUEST_SENSE, UFI devices only ever return 18 bytes */
166 } /* end switch on cmnd[0] */
168 /* send the command to the transport layer */
169 usb_stor_invoke_transport(srb, us);
172 void usb_stor_transparent_scsi_command(struct scsi_cmnd *srb,
175 /* send the command to the transport layer */
176 usb_stor_invoke_transport(srb, us);
178 if (srb->result == SAM_STAT_GOOD) {
179 /* Fix the READ CAPACITY result if necessary */
180 if (us->flags & US_FL_FIX_CAPACITY)
181 fix_read_capacity(srb);
185 /***********************************************************************
186 * Scatter-gather transfer buffer access routines
187 ***********************************************************************/
189 /* Copy a buffer of length buflen to/from the srb's transfer buffer.
190 * (Note: for scatter-gather transfers (srb->use_sg > 0), srb->request_buffer
191 * points to a list of s-g entries and we ignore srb->request_bufflen.
192 * For non-scatter-gather transfers, srb->request_buffer points to the
193 * transfer buffer itself and srb->request_bufflen is the buffer's length.)
194 * Update the *index and *offset variables so that the next copy will
195 * pick up from where this one left off. */
197 unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
198 unsigned int buflen, struct scsi_cmnd *srb, unsigned int *index,
199 unsigned int *offset, enum xfer_buf_dir dir)
203 /* If not using scatter-gather, just transfer the data directly.
204 * Make certain it will fit in the available buffer space. */
205 if (srb->use_sg == 0) {
206 if (*offset >= srb->request_bufflen)
208 cnt = min(buflen, srb->request_bufflen - *offset);
209 if (dir == TO_XFER_BUF)
210 memcpy((unsigned char *) srb->request_buffer + *offset,
213 memcpy(buffer, (unsigned char *) srb->request_buffer +
217 /* Using scatter-gather. We have to go through the list one entry
218 * at a time. Each s-g entry contains some number of pages, and
219 * each page has to be kmap()'ed separately. If the page is already
220 * in kernel-addressable memory then kmap() will return its address.
221 * If the page is not directly accessible -- such as a user buffer
222 * located in high memory -- then kmap() will map it to a temporary
223 * position in the kernel's virtual address space. */
225 struct scatterlist *sg =
226 (struct scatterlist *) srb->request_buffer
229 /* This loop handles a single s-g list entry, which may
230 * include multiple pages. Find the initial page structure
231 * and the starting offset within the page, and update
232 * the *offset and *index values for the next loop. */
234 while (cnt < buflen && *index < srb->use_sg) {
235 struct page *page = sg->page +
236 ((sg->offset + *offset) >> PAGE_SHIFT);
238 (sg->offset + *offset) & (PAGE_SIZE-1);
239 unsigned int sglen = sg->length - *offset;
241 if (sglen > buflen - cnt) {
243 /* Transfer ends within this s-g entry */
244 sglen = buflen - cnt;
248 /* Transfer continues to next s-g entry */
254 /* Transfer the data for all the pages in this
255 * s-g entry. For each page: call kmap(), do the
256 * transfer, and call kunmap() immediately after. */
258 unsigned int plen = min(sglen, (unsigned int)
260 unsigned char *ptr = kmap(page);
262 if (dir == TO_XFER_BUF)
263 memcpy(ptr + poff, buffer + cnt, plen);
265 memcpy(buffer + cnt, ptr + poff, plen);
268 /* Start at the beginning of the next page */
277 /* Return the amount actually transferred */
281 /* Store the contents of buffer into srb's transfer buffer and set the
283 void usb_stor_set_xfer_buf(unsigned char *buffer,
284 unsigned int buflen, struct scsi_cmnd *srb)
286 unsigned int index = 0, offset = 0;
288 usb_stor_access_xfer_buf(buffer, buflen, srb, &index, &offset,
290 if (buflen < srb->request_bufflen)
291 srb->resid = srb->request_bufflen - buflen;