1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* |
3 | * Driver for USB Mass Storage compliant devices |
4 | * |
5 | * Current development and maintenance by: |
6 | * (c) 1999-2002 Matthew Dharm (mdharm-usb@one-eyed-alien.net) |
7 | * |
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) |
11 | * |
12 | * Initial work by: |
13 | * (c) 1999 Michael Gee (michael@linuxspecific.com) |
14 | * |
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. |
20 | * |
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. |
25 | * |
26 | * Also, for certain devices, the interrupt endpoint is used to convey |
27 | * status of a command. |
28 | */ |
29 | |
30 | #include <linux/highmem.h> |
31 | #include <linux/export.h> |
32 | #include <scsi/scsi.h> |
33 | #include <scsi/scsi_cmnd.h> |
34 | |
35 | #include "usb.h" |
36 | #include "protocol.h" |
37 | #include "debug.h" |
38 | #include "scsiglue.h" |
39 | #include "transport.h" |
40 | |
41 | /*********************************************************************** |
42 | * Protocol routines |
43 | ***********************************************************************/ |
44 | |
45 | void usb_stor_pad12_command(struct scsi_cmnd *srb, struct us_data *us) |
46 | { |
47 | /* |
48 | * Pad the SCSI command with zeros out to 12 bytes. If the |
49 | * command already is 12 bytes or longer, leave it alone. |
50 | * |
51 | * NOTE: This only works because a scsi_cmnd struct field contains |
52 | * a unsigned char cmnd[16], so we know we have storage available |
53 | */ |
54 | for (; srb->cmd_len < 12; srb->cmd_len++) |
55 | srb->cmnd[srb->cmd_len] = 0; |
56 | |
57 | /* send the command to the transport layer */ |
58 | usb_stor_invoke_transport(srb, us); |
59 | } |
60 | |
61 | void usb_stor_ufi_command(struct scsi_cmnd *srb, struct us_data *us) |
62 | { |
63 | /* |
64 | * fix some commands -- this is a form of mode translation |
65 | * UFI devices only accept 12 byte long commands |
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 | |
71 | /* Pad the ATAPI command with zeros */ |
72 | for (; srb->cmd_len < 12; srb->cmd_len++) |
73 | srb->cmnd[srb->cmd_len] = 0; |
74 | |
75 | /* set command length to 12 bytes (this affects the transport layer) */ |
76 | srb->cmd_len = 12; |
77 | |
78 | /* XXX We should be constantly re-evaluating the need for these */ |
79 | |
80 | /* determine the correct data length for these commands */ |
81 | switch (srb->cmnd[0]) { |
82 | |
83 | /* for INQUIRY, UFI devices only ever return 36 bytes */ |
84 | case INQUIRY: |
85 | srb->cmnd[4] = 36; |
86 | break; |
87 | |
88 | /* again, for MODE_SENSE_10, we get the minimum (8) */ |
89 | case MODE_SENSE_10: |
90 | srb->cmnd[7] = 0; |
91 | srb->cmnd[8] = 8; |
92 | break; |
93 | |
94 | /* for REQUEST_SENSE, UFI devices only ever return 18 bytes */ |
95 | case REQUEST_SENSE: |
96 | srb->cmnd[4] = 18; |
97 | break; |
98 | } /* end switch on cmnd[0] */ |
99 | |
100 | /* send the command to the transport layer */ |
101 | usb_stor_invoke_transport(srb, us); |
102 | } |
103 | |
104 | void usb_stor_transparent_scsi_command(struct scsi_cmnd *srb, |
105 | struct us_data *us) |
106 | { |
107 | /* send the command to the transport layer */ |
108 | usb_stor_invoke_transport(srb, us); |
109 | } |
110 | EXPORT_SYMBOL_GPL(usb_stor_transparent_scsi_command); |
111 | |
112 | /*********************************************************************** |
113 | * Scatter-gather transfer buffer access routines |
114 | ***********************************************************************/ |
115 | |
116 | /* |
117 | * Copy a buffer of length buflen to/from the srb's transfer buffer. |
118 | * Update the **sgptr and *offset variables so that the next copy will |
119 | * pick up from where this one left off. |
120 | */ |
121 | unsigned int usb_stor_access_xfer_buf(unsigned char *buffer, |
122 | unsigned int buflen, struct scsi_cmnd *srb, struct scatterlist **sgptr, |
123 | unsigned int *offset, enum xfer_buf_dir dir) |
124 | { |
125 | unsigned int cnt = 0; |
126 | struct scatterlist *sg = *sgptr; |
127 | struct sg_mapping_iter miter; |
128 | unsigned int nents = scsi_sg_count(cmd: srb); |
129 | |
130 | if (sg) |
131 | nents = sg_nents(sg); |
132 | else |
133 | sg = scsi_sglist(cmd: srb); |
134 | |
135 | sg_miter_start(miter: &miter, sgl: sg, nents, flags: dir == FROM_XFER_BUF ? |
136 | SG_MITER_FROM_SG: SG_MITER_TO_SG); |
137 | |
138 | if (!sg_miter_skip(miter: &miter, offset: *offset)) |
139 | return cnt; |
140 | |
141 | while (sg_miter_next(miter: &miter) && cnt < buflen) { |
142 | unsigned int len = min_t(unsigned int, miter.length, |
143 | buflen - cnt); |
144 | |
145 | if (dir == FROM_XFER_BUF) |
146 | memcpy(buffer + cnt, miter.addr, len); |
147 | else |
148 | memcpy(miter.addr, buffer + cnt, len); |
149 | |
150 | if (*offset + len < miter.piter.sg->length) { |
151 | *offset += len; |
152 | *sgptr = miter.piter.sg; |
153 | } else { |
154 | *offset = 0; |
155 | *sgptr = sg_next(miter.piter.sg); |
156 | } |
157 | cnt += len; |
158 | } |
159 | sg_miter_stop(miter: &miter); |
160 | |
161 | return cnt; |
162 | } |
163 | EXPORT_SYMBOL_GPL(usb_stor_access_xfer_buf); |
164 | |
165 | /* |
166 | * Store the contents of buffer into srb's transfer buffer and set the |
167 | * SCSI residue. |
168 | */ |
169 | void usb_stor_set_xfer_buf(unsigned char *buffer, |
170 | unsigned int buflen, struct scsi_cmnd *srb) |
171 | { |
172 | unsigned int offset = 0; |
173 | struct scatterlist *sg = NULL; |
174 | |
175 | buflen = min(buflen, scsi_bufflen(srb)); |
176 | buflen = usb_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset, |
177 | TO_XFER_BUF); |
178 | if (buflen < scsi_bufflen(cmd: srb)) |
179 | scsi_set_resid(cmd: srb, resid: scsi_bufflen(cmd: srb) - buflen); |
180 | } |
181 | EXPORT_SYMBOL_GPL(usb_stor_set_xfer_buf); |
182 | |