/* Driver for USB Mass Storage compliant devices * * $Id: protocol.c,v 1.14 2002/04/22 03:39:43 mdharm Exp $ * * 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 #include #include #include "usb.h" #include "protocol.h" #include "debug.h" #include "scsiglue.h" #include "transport.h" /*********************************************************************** * Protocol routines ***********************************************************************/ void usb_stor_qic157_command(struct scsi_cmnd *srb, struct us_data *us) { /* Pad the ATAPI command with zeros * * 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; /* set command length to 12 bytes */ srb->cmd_len = 12; /* send the command to the transport layer */ usb_stor_invoke_transport(srb, us); } void usb_stor_ATAPI_command(struct scsi_cmnd *srb, struct us_data *us) { /* Pad the ATAPI command with zeros * * 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 */ srb->cmd_len = 12; /* 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); } /*********************************************************************** * Scatter-gather transfer buffer access routines ***********************************************************************/ /* Copy a buffer of length buflen to/from the srb's transfer buffer. * (Note: for scatter-gather transfers (srb->use_sg > 0), srb->request_buffer * points to a list of s-g entries and we ignore srb->request_bufflen. * For non-scatter-gather transfers, srb->request_buffer points to the * transfer buffer itself and srb->request_bufflen is the buffer's length.) * Update the *index 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, unsigned int *index, unsigned int *offset, enum xfer_buf_dir dir) { unsigned int cnt; /* If not using scatter-gather, just transfer the data directly. * Make certain it will fit in the available buffer space. */ if (srb->use_sg == 0) { if (*offset >= srb->request_bufflen) return 0; cnt = min(buflen, srb->request_bufflen - *offset); if (dir == TO_XFER_BUF) memcpy((unsigned char *) srb->request_buffer + *offset, buffer, cnt); else memcpy(buffer, (unsigned char *) srb->request_buffer + *offset, cnt); *offset += cnt; /* Using scatter-gather. 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. */ } else { struct scatterlist *sg = (struct scatterlist *) srb->request_buffer + *index; /* 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 *index values for the next loop. */ cnt = 0; while (cnt < buflen && *index < srb->use_sg) { struct page *page = sg->page + ((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 { /* Transfer continues to next s-g entry */ *offset = 0; ++*index; ++sg; } /* 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; } } } /* Return the amount actually transferred */ return cnt; } /* 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 index = 0, offset = 0; usb_stor_access_xfer_buf(buffer, buflen, srb, &index, &offset, TO_XFER_BUF); if (buflen < srb->request_bufflen) srb->resid = srb->request_bufflen - buflen; }