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

/* 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
1da177e4	1	/* Driver for USB Mass Storage compliant devices
1da177e4 LT	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>
f940fcd8	46	#include <linux/export.h>
1da177e4 LT	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
3dae5345	60	void usb_stor_pad12_command(struct scsi_cmnd srb, struct us_data us)
1da177e4	61	{
2f640bf4 AS	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.
1da177e4 LT	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	*/
fc8ef481	69	for (; srb->cmd_len < 12; srb->cmd_len++)
1da177e4 LT	70	srb->cmnd[srb->cmd_len] = 0;
1da177e4 LT	71
1da177e4 LT	72	/* send the command to the transport layer */
	73	usb_stor_invoke_transport(srb, us);
	74	}
	75
1da177e4 LT	76	void usb_stor_ufi_command(struct scsi_cmnd srb, struct us_data us)
	77	{
	78	/* fix some commands -- this is a form of mode translation
fc8ef481	79	* UFI devices only accept 12 byte long commands
1da177e4 LT	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 */
fc8ef481	86	for (; srb->cmd_len < 12; srb->cmd_len++)
1da177e4 LT	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
	118	void 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	}
e6e244b6	124	EXPORT_SYMBOL_GPL(usb_stor_transparent_scsi_command);
1da177e4 LT	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.
dd829d23	131	* Update the *sgptr and offset variables so that the next copy will
7084191d AS	132	* pick up from where this one left off.
7084191d AS	133	*/
1da177e4	134	unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
1f6f31a0	135	unsigned int buflen, struct scsi_cmnd srb, struct scatterlist *sgptr,
1da177e4 LT	136	unsigned int *offset, enum xfer_buf_dir dir)
1da177e4 LT	137	{
e5fc70d5	138	unsigned int cnt = 0;
7084191d	139	struct scatterlist sg = sgptr;
e5fc70d5 ML	140	struct sg_mapping_iter miter;
e5fc70d5 ML	141	unsigned int nents = scsi_sg_count(srb);
1da177e4	142
e5fc70d5 ML	143	if (sg)
	144	nents = sg_nents(sg);
	145	else
dd829d23 BH	146	sg = scsi_sglist(srb);
dd829d23 BH	147
e5fc70d5 ML	148	sg_miter_start(&miter, sg, nents, dir == FROM_XFER_BUF ?
e5fc70d5 ML	149	SG_MITER_FROM_SG: SG_MITER_TO_SG);
dd829d23	150
e5fc70d5 ML	151	if (!sg_miter_skip(&miter, *offset))
	152	return cnt;
	153
	154	while (sg_miter_next(&miter) && cnt < buflen) {
40fcd88b ML	155	unsigned int len = min_t(unsigned int, miter.length,
40fcd88b ML	156	buflen - cnt);
e5fc70d5 ML	157
	158	if (dir == FROM_XFER_BUF)
	159	memcpy(buffer + cnt, miter.addr, len);
	160	else
	161	memcpy(miter.addr, buffer + cnt, len);
dd829d23	162
e5fc70d5 ML	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);
1da177e4	169	}
e5fc70d5	170	cnt += len;
1da177e4	171	}
e5fc70d5	172	sg_miter_stop(&miter);
1da177e4	173
1da177e4 LT	174	return cnt;
1da177e4 LT	175	}
e6e244b6	176	EXPORT_SYMBOL_GPL(usb_stor_access_xfer_buf);
1da177e4 LT	177
1da177e4 LT	178	/* Store the contents of buffer into srb's transfer buffer and set the
7084191d AS	179	* SCSI residue.
7084191d AS	180	*/
1da177e4 LT	181	void usb_stor_set_xfer_buf(unsigned char *buffer,
	182	unsigned int buflen, struct scsi_cmnd *srb)
	183	{
1f6f31a0 JA	184	unsigned int offset = 0;
1f6f31a0 JA	185	struct scatterlist *sg = NULL;
1da177e4	186
6d512a80	187	buflen = min(buflen, scsi_bufflen(srb));
7084191d	188	buflen = usb_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset,
1da177e4	189	TO_XFER_BUF);
dd829d23 BH	190	if (buflen < scsi_bufflen(srb))
dd829d23 BH	191	scsi_set_resid(srb, scsi_bufflen(srb) - buflen);
1da177e4	192	}
e6e244b6	193	EXPORT_SYMBOL_GPL(usb_stor_set_xfer_buf);