diff options
Diffstat (limited to 'drivers/usb/storage/protocol.c')
| -rw-r--r-- | drivers/usb/storage/protocol.c | 110 |
1 files changed, 35 insertions, 75 deletions
diff --git a/drivers/usb/storage/protocol.c b/drivers/usb/storage/protocol.c index 5dfb4c36a1b0..0cff54ad90fa 100644 --- a/drivers/usb/storage/protocol.c +++ b/drivers/usb/storage/protocol.c @@ -1,4 +1,6 @@ -/* Driver for USB Mass Storage compliant devices +// 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) @@ -23,23 +25,6 @@ * * 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> @@ -75,7 +60,8 @@ void usb_stor_pad12_command(struct scsi_cmnd *srb, struct us_data *us) void usb_stor_ufi_command(struct scsi_cmnd *srb, struct us_data *us) { - /* fix some commands -- this is a form of mode translation + /* + * 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 @@ -127,7 +113,8 @@ 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. +/* + * 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. */ @@ -135,74 +122,47 @@ 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; + unsigned int cnt = 0; struct scatterlist *sg = *sgptr; + struct sg_mapping_iter miter; + unsigned int nents = scsi_sg_count(srb); - /* We have to go through the list one entry - * at a time. Each s-g entry contains some number of pages, and - * each page has to be kmap()'ed separately. If the page is already - * in kernel-addressable memory then kmap() will return its address. - * If the page is not directly accessible -- such as a user buffer - * located in high memory -- then kmap() will map it to a temporary - * position in the kernel's virtual address space. - */ - - if (!sg) + if (sg) + nents = sg_nents(sg); + else sg = scsi_sglist(srb); - /* This loop handles a single s-g list entry, which may - * include multiple pages. Find the initial page structure - * and the starting offset within the page, and update - * the *offset and **sgptr values for the next loop. - */ - cnt = 0; - while (cnt < buflen && sg) { - struct page *page = sg_page(sg) + - ((sg->offset + *offset) >> PAGE_SHIFT); - unsigned int poff = (sg->offset + *offset) & (PAGE_SIZE-1); - unsigned int sglen = sg->length - *offset; - - if (sglen > buflen - cnt) { - - /* Transfer ends within this s-g entry */ - sglen = buflen - cnt; - *offset += sglen; - } else { + sg_miter_start(&miter, sg, nents, dir == FROM_XFER_BUF ? + SG_MITER_FROM_SG: SG_MITER_TO_SG); - /* Transfer continues to next s-g entry */ - *offset = 0; - sg = sg_next(sg); - } + if (!sg_miter_skip(&miter, *offset)) + return cnt; + + while (sg_miter_next(&miter) && cnt < buflen) { + unsigned int len = min(miter.length, buflen - cnt); - /* Transfer the data for all the pages in this - * s-g entry. For each page: call kmap(), do the - * transfer, and call kunmap() immediately after. */ - while (sglen > 0) { - unsigned int plen = min(sglen, (unsigned int) - PAGE_SIZE - poff); - unsigned char *ptr = kmap(page); - - if (dir == TO_XFER_BUF) - memcpy(ptr + poff, buffer + cnt, plen); - else - memcpy(buffer + cnt, ptr + poff, plen); - kunmap(page); - - /* Start at the beginning of the next page */ - poff = 0; - ++page; - cnt += plen; - sglen -= plen; + 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; } - *sgptr = sg; + sg_miter_stop(&miter); - /* Return the amount actually transferred */ return cnt; } EXPORT_SYMBOL_GPL(usb_stor_access_xfer_buf); -/* Store the contents of buffer into srb's transfer buffer and set the +/* + * Store the contents of buffer into srb's transfer buffer and set the * SCSI residue. */ void usb_stor_set_xfer_buf(unsigned char *buffer, |