[linux-2.6-block.git] / drivers / usb / storage / protocol.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Driver for USB Mass Storage compliant devices
 *
 * Current development and maintenance by:
 *   (c) 1999-2002 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
 *
 * Developed with the assistance of:
 *   (c) 2000 David L. Brown, Jr. (usb-storage@davidb.org)
 *   (c) 2002 Alan Stern (stern@rowland.org)
 *
 * Initial work by:
 *   (c) 1999 Michael Gee (michael@linuxspecific.com)
 *
 * This driver is based on the 'USB Mass Storage Class' document. This
 * describes in detail the protocol used to communicate with such
 * devices.  Clearly, the designers had SCSI and ATAPI commands in
 * mind when they created this document.  The commands are all very
 * similar to commands in the SCSI-II and ATAPI specifications.
 *
 * It is important to note that in a number of cases this class
 * exhibits class-specific exemptions from the USB specification.
 * Notably the usage of NAK, STALL and ACK differs from the norm, in
 * that they are used to communicate wait, failed and OK on commands.
 *
 * Also, for certain devices, the interrupt endpoint is used to convey
 * status of a command.
 *
 * Please see http://www.one-eyed-alien.net/~mdharm/linux-usb for more
 * information about this driver.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/highmem.h>
#include <linux/export.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>

#include "usb.h"
#include "protocol.h"
#include "debug.h"
#include "scsiglue.h"
#include "transport.h"

/***********************************************************************
 * Protocol routines
 ***********************************************************************/

void usb_stor_pad12_command(struct scsi_cmnd *srb, struct us_data *us)
{
	/*
	 * Pad the SCSI command with zeros out to 12 bytes.  If the
	 * command already is 12 bytes or longer, leave it alone.
	 *
	 * NOTE: This only works because a scsi_cmnd struct field contains
	 * a unsigned char cmnd[16], so we know we have storage available
	 */
	for (; srb->cmd_len < 12; srb->cmd_len++)
		srb->cmnd[srb->cmd_len] = 0;

	/* send the command to the transport layer */
	usb_stor_invoke_transport(srb, us);
}

void usb_stor_ufi_command(struct scsi_cmnd *srb, struct us_data *us)
{
	/*
	 * fix some commands -- this is a form of mode translation
	 * UFI devices only accept 12 byte long commands
	 *
	 * NOTE: This only works because a scsi_cmnd struct field contains
	 * a unsigned char cmnd[16], so we know we have storage available
	 */

	/* Pad the ATAPI command with zeros */
	for (; srb->cmd_len < 12; srb->cmd_len++)
		srb->cmnd[srb->cmd_len] = 0;

	/* set command length to 12 bytes (this affects the transport layer) */
	srb->cmd_len = 12;

	/* XXX We should be constantly re-evaluating the need for these */

	/* determine the correct data length for these commands */
	switch (srb->cmnd[0]) {

		/* for INQUIRY, UFI devices only ever return 36 bytes */
	case INQUIRY:
		srb->cmnd[4] = 36;
		break;

		/* again, for MODE_SENSE_10, we get the minimum (8) */
	case MODE_SENSE_10:
		srb->cmnd[7] = 0;
		srb->cmnd[8] = 8;
		break;

		/* for REQUEST_SENSE, UFI devices only ever return 18 bytes */
	case REQUEST_SENSE:
		srb->cmnd[4] = 18;
		break;
	} /* end switch on cmnd[0] */

	/* send the command to the transport layer */
	usb_stor_invoke_transport(srb, us);
}

void usb_stor_transparent_scsi_command(struct scsi_cmnd *srb,
				       struct us_data *us)
{
	/* send the command to the transport layer */
	usb_stor_invoke_transport(srb, us);
}
EXPORT_SYMBOL_GPL(usb_stor_transparent_scsi_command);

/***********************************************************************
 * Scatter-gather transfer buffer access routines
 ***********************************************************************/

/*
 * Copy a buffer of length buflen to/from the srb's transfer buffer.
 * Update the **sgptr and *offset variables so that the next copy will
 * pick up from where this one left off.
 */
unsigned int 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)
{
	unsigned int cnt = 0;
	struct scatterlist *sg = *sgptr;
	struct sg_mapping_iter miter;
	unsigned int nents = scsi_sg_count(srb);

	if (sg)
		nents = sg_nents(sg);
	else
		sg = scsi_sglist(srb);

	sg_miter_start(&miter, sg, nents, dir == FROM_XFER_BUF ?
		SG_MITER_FROM_SG: SG_MITER_TO_SG);

	if (!sg_miter_skip(&miter, *offset))
		return cnt;

	while (sg_miter_next(&miter) && cnt < buflen) {
		unsigned int len = min_t(unsigned int, miter.length,
				buflen - cnt);

		if (dir == FROM_XFER_BUF)
			memcpy(buffer + cnt, miter.addr, len);
		else
			memcpy(miter.addr, buffer + cnt, len);

		if (*offset + len < miter.piter.sg->length) {
			*offset += len;
			*sgptr = miter.piter.sg;
		} else {
			*offset = 0;
			*sgptr = sg_next(miter.piter.sg);
		}
		cnt += len;
	}
	sg_miter_stop(&miter);

	return cnt;
}
EXPORT_SYMBOL_GPL(usb_stor_access_xfer_buf);

/*
 * Store the contents of buffer into srb's transfer buffer and set the
 * SCSI residue.
 */
void usb_stor_set_xfer_buf(unsigned char *buffer,
	unsigned int buflen, struct scsi_cmnd *srb)
{
	unsigned int offset = 0;
	struct scatterlist *sg = NULL;

	buflen = min(buflen, scsi_bufflen(srb));
	buflen = usb_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset,
			TO_XFER_BUF);
	if (buflen < scsi_bufflen(srb))
		scsi_set_resid(srb, scsi_bufflen(srb) - buflen);
}
EXPORT_SYMBOL_GPL(usb_stor_set_xfer_buf);
Commit	Line	Data
5fd54ace	1	// SPDX-License-Identifier: GPL-2.0+
f0183a33 FB	2	/*
f0183a33 FB	3	* Driver for USB Mass Storage compliant devices
1da177e4 LT	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	* Please see http://www.one-eyed-alien.net/~mdharm/linux-usb for more
	30	* information about this driver.
	31	*
	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
	35	* later version.
	36	*
	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.
	41	*
	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.
	45	*/
	46
	47	#include <linux/highmem.h>
f940fcd8	48	#include <linux/export.h>
1da177e4 LT	49	#include <scsi/scsi.h>
	50	#include <scsi/scsi_cmnd.h>
	51
	52	#include "usb.h"
	53	#include "protocol.h"
	54	#include "debug.h"
	55	#include "scsiglue.h"
	56	#include "transport.h"
	57
	58	/***********************************************************************
	59	* Protocol routines
	60	***********************************************************************/
	61
3dae5345	62	void usb_stor_pad12_command(struct scsi_cmnd srb, struct us_data us)
1da177e4	63	{
2f640bf4 AS	64	/*
	65	* Pad the SCSI command with zeros out to 12 bytes. If the
	66	* command already is 12 bytes or longer, leave it alone.
1da177e4 LT	67	*
	68	* NOTE: This only works because a scsi_cmnd struct field contains
	69	* a unsigned char cmnd[16], so we know we have storage available
	70	*/
fc8ef481	71	for (; srb->cmd_len < 12; srb->cmd_len++)
1da177e4 LT	72	srb->cmnd[srb->cmd_len] = 0;
1da177e4 LT	73
1da177e4 LT	74	/* send the command to the transport layer */
	75	usb_stor_invoke_transport(srb, us);
	76	}
	77
1da177e4 LT	78	void usb_stor_ufi_command(struct scsi_cmnd srb, struct us_data us)
1da177e4 LT	79	{
f0183a33 FB	80	/*
f0183a33 FB	81	* fix some commands -- this is a form of mode translation
fc8ef481	82	* UFI devices only accept 12 byte long commands
1da177e4 LT	83	*
	84	* NOTE: This only works because a scsi_cmnd struct field contains
	85	* a unsigned char cmnd[16], so we know we have storage available
	86	*/
	87
	88	/* Pad the ATAPI command with zeros */
fc8ef481	89	for (; srb->cmd_len < 12; srb->cmd_len++)
1da177e4 LT	90	srb->cmnd[srb->cmd_len] = 0;
	91
	92	/* set command length to 12 bytes (this affects the transport layer) */
	93	srb->cmd_len = 12;
	94
	95	/* XXX We should be constantly re-evaluating the need for these */
	96
	97	/* determine the correct data length for these commands */
	98	switch (srb->cmnd[0]) {
	99
	100	/* for INQUIRY, UFI devices only ever return 36 bytes */
	101	case INQUIRY:
	102	srb->cmnd[4] = 36;
	103	break;
	104
	105	/* again, for MODE_SENSE_10, we get the minimum (8) */
	106	case MODE_SENSE_10:
	107	srb->cmnd[7] = 0;
	108	srb->cmnd[8] = 8;
	109	break;
	110
	111	/* for REQUEST_SENSE, UFI devices only ever return 18 bytes */
	112	case REQUEST_SENSE:
	113	srb->cmnd[4] = 18;
	114	break;
	115	} /* end switch on cmnd[0] */
	116
	117	/* send the command to the transport layer */
	118	usb_stor_invoke_transport(srb, us);
	119	}
	120
	121	void usb_stor_transparent_scsi_command(struct scsi_cmnd *srb,
	122	struct us_data *us)
	123	{
	124	/* send the command to the transport layer */
	125	usb_stor_invoke_transport(srb, us);
	126	}
e6e244b6	127	EXPORT_SYMBOL_GPL(usb_stor_transparent_scsi_command);
1da177e4 LT	128
	129	/***********************************************************************
	130	* Scatter-gather transfer buffer access routines
	131	***********************************************************************/
	132
f0183a33 FB	133	/*
f0183a33 FB	134	* Copy a buffer of length buflen to/from the srb's transfer buffer.
dd829d23	135	* Update the *sgptr and offset variables so that the next copy will
7084191d AS	136	* pick up from where this one left off.
7084191d AS	137	*/
1da177e4	138	unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
1f6f31a0	139	unsigned int buflen, struct scsi_cmnd srb, struct scatterlist *sgptr,
1da177e4 LT	140	unsigned int *offset, enum xfer_buf_dir dir)
1da177e4 LT	141	{
e5fc70d5	142	unsigned int cnt = 0;
7084191d	143	struct scatterlist sg = sgptr;
e5fc70d5 ML	144	struct sg_mapping_iter miter;
e5fc70d5 ML	145	unsigned int nents = scsi_sg_count(srb);
1da177e4	146
e5fc70d5 ML	147	if (sg)
	148	nents = sg_nents(sg);
	149	else
dd829d23 BH	150	sg = scsi_sglist(srb);
dd829d23 BH	151
e5fc70d5 ML	152	sg_miter_start(&miter, sg, nents, dir == FROM_XFER_BUF ?
e5fc70d5 ML	153	SG_MITER_FROM_SG: SG_MITER_TO_SG);
dd829d23	154
e5fc70d5 ML	155	if (!sg_miter_skip(&miter, *offset))
	156	return cnt;
	157
	158	while (sg_miter_next(&miter) && cnt < buflen) {
40fcd88b ML	159	unsigned int len = min_t(unsigned int, miter.length,
40fcd88b ML	160	buflen - cnt);
e5fc70d5 ML	161
	162	if (dir == FROM_XFER_BUF)
	163	memcpy(buffer + cnt, miter.addr, len);
	164	else
	165	memcpy(miter.addr, buffer + cnt, len);
dd829d23	166
e5fc70d5 ML	167	if (*offset + len < miter.piter.sg->length) {
	168	*offset += len;
	169	*sgptr = miter.piter.sg;
	170	} else {
	171	*offset = 0;
	172	*sgptr = sg_next(miter.piter.sg);
1da177e4	173	}
e5fc70d5	174	cnt += len;
1da177e4	175	}
e5fc70d5	176	sg_miter_stop(&miter);
1da177e4	177
1da177e4 LT	178	return cnt;
1da177e4 LT	179	}
e6e244b6	180	EXPORT_SYMBOL_GPL(usb_stor_access_xfer_buf);
1da177e4	181
f0183a33 FB	182	/*
f0183a33 FB	183	* Store the contents of buffer into srb's transfer buffer and set the
7084191d AS	184	* SCSI residue.
7084191d AS	185	*/
1da177e4 LT	186	void usb_stor_set_xfer_buf(unsigned char *buffer,
	187	unsigned int buflen, struct scsi_cmnd *srb)
	188	{
1f6f31a0 JA	189	unsigned int offset = 0;
1f6f31a0 JA	190	struct scatterlist *sg = NULL;
1da177e4	191
6d512a80	192	buflen = min(buflen, scsi_bufflen(srb));
7084191d	193	buflen = usb_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset,
1da177e4	194	TO_XFER_BUF);
dd829d23 BH	195	if (buflen < scsi_bufflen(srb))
dd829d23 BH	196	scsi_set_resid(srb, scsi_bufflen(srb) - buflen);
1da177e4	197	}
e6e244b6	198	EXPORT_SYMBOL_GPL(usb_stor_set_xfer_buf);