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linux/drivers/usb/gadget/storage_common.c

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/*
* storage_common.c -- Common definitions for mass storage functionality
*
* Copyright (C) 2003-2008 Alan Stern
* Copyeight (C) 2009 Samsung Electronics
* Author: Michal Nazarewicz (m.nazarewicz@samsung.com)
*
* 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 of the License, 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* This file requires the following identifiers used in USB strings to
* be defined (each of type pointer to char):
* - fsg_string_manufacturer -- name of the manufacturer
* - fsg_string_product -- name of the product
* - fsg_string_serial -- product's serial
* - fsg_string_config -- name of the configuration
* - fsg_string_interface -- name of the interface
* The first four are only needed when FSG_DESCRIPTORS_DEVICE_STRINGS
* macro is defined prior to including this file.
*/
/*
* When FSG_NO_INTR_EP is defined fsg_fs_intr_in_desc and
* fsg_hs_intr_in_desc objects as well as
* FSG_FS_FUNCTION_PRE_EP_ENTRIES and FSG_HS_FUNCTION_PRE_EP_ENTRIES
* macros are not defined.
*
* When FSG_NO_DEVICE_STRINGS is defined FSG_STRING_MANUFACTURER,
* FSG_STRING_PRODUCT, FSG_STRING_SERIAL and FSG_STRING_CONFIG are not
* defined (as well as corresponding entries in string tables are
* missing) and FSG_STRING_INTERFACE has value of zero.
*
* When FSG_NO_OTG is defined fsg_otg_desc won't be defined.
*/
/*
* When FSG_BUFFHD_STATIC_BUFFER is defined when this file is included
* the fsg_buffhd structure's buf field will be an array of FSG_BUFLEN
* characters rather then a pointer to void.
*/
#include <asm/unaligned.h>
/* Thanks to NetChip Technologies for donating this product ID.
*
* DO NOT REUSE THESE IDs with any other driver!! Ever!!
* Instead: allocate your own, using normal USB-IF procedures. */
#define FSG_VENDOR_ID 0x0525 /* NetChip */
#define FSG_PRODUCT_ID 0xa4a5 /* Linux-USB File-backed Storage Gadget */
/*-------------------------------------------------------------------------*/
#ifndef DEBUG
#undef VERBOSE_DEBUG
#undef DUMP_MSGS
#endif /* !DEBUG */
#ifdef VERBOSE_DEBUG
#define VLDBG LDBG
#else
#define VLDBG(lun, fmt, args...) do { } while (0)
#endif /* VERBOSE_DEBUG */
#define LDBG(lun, fmt, args...) dev_dbg (&(lun)->dev, fmt, ## args)
#define LERROR(lun, fmt, args...) dev_err (&(lun)->dev, fmt, ## args)
#define LWARN(lun, fmt, args...) dev_warn(&(lun)->dev, fmt, ## args)
#define LINFO(lun, fmt, args...) dev_info(&(lun)->dev, fmt, ## args)
/* Keep those macros in sync with thos in
* include/linux/ubs/composite.h or else GCC will complain. If they
* are identical (the same names of arguments, white spaces in the
* same places) GCC will allow redefinition otherwise (even if some
* white space is removed or added) warning will be issued. No
* checking if those symbols is defined is performed because warning
* is desired when those macros were defined by someone else to mean
* something else. */
#define DBG(d, fmt, args...) dev_dbg(&(d)->gadget->dev , fmt , ## args)
#define VDBG(d, fmt, args...) dev_vdbg(&(d)->gadget->dev , fmt , ## args)
#define ERROR(d, fmt, args...) dev_err(&(d)->gadget->dev , fmt , ## args)
#define WARNING(d, fmt, args...) dev_warn(&(d)->gadget->dev , fmt , ## args)
#define INFO(d, fmt, args...) dev_info(&(d)->gadget->dev , fmt , ## args)
#ifdef DUMP_MSGS
# define dump_msg(fsg, /* const char * */ label, \
/* const u8 * */ buf, /* unsigned */ length) do { \
if (length < 512) { \
DBG(fsg, "%s, length %u:\n", label, length); \
print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, \
16, 1, buf, length, 0); \
} \
} while (0)
# define dump_cdb(fsg) do { } while (0)
#else
# define dump_msg(fsg, /* const char * */ label, \
/* const u8 * */ buf, /* unsigned */ length) do { } while (0)
# ifdef VERBOSE_DEBUG
# define dump_cdb(fsg) \
print_hex_dump(KERN_DEBUG, "SCSI CDB: ", DUMP_PREFIX_NONE, \
16, 1, (fsg)->cmnd, (fsg)->cmnd_size, 0) \
# else
# define dump_cdb(fsg) do { } while (0)
# endif /* VERBOSE_DEBUG */
#endif /* DUMP_MSGS */
/*-------------------------------------------------------------------------*/
/* SCSI device types */
#define TYPE_DISK 0x00
#define TYPE_CDROM 0x05
/* USB protocol value = the transport method */
#define USB_PR_CBI 0x00 /* Control/Bulk/Interrupt */
#define USB_PR_CB 0x01 /* Control/Bulk w/o interrupt */
#define USB_PR_BULK 0x50 /* Bulk-only */
/* USB subclass value = the protocol encapsulation */
#define USB_SC_RBC 0x01 /* Reduced Block Commands (flash) */
#define USB_SC_8020 0x02 /* SFF-8020i, MMC-2, ATAPI (CD-ROM) */
#define USB_SC_QIC 0x03 /* QIC-157 (tape) */
#define USB_SC_UFI 0x04 /* UFI (floppy) */
#define USB_SC_8070 0x05 /* SFF-8070i (removable) */
#define USB_SC_SCSI 0x06 /* Transparent SCSI */
/* Bulk-only data structures */
/* Command Block Wrapper */
struct fsg_bulk_cb_wrap {
__le32 Signature; /* Contains 'USBC' */
u32 Tag; /* Unique per command id */
__le32 DataTransferLength; /* Size of the data */
u8 Flags; /* Direction in bit 7 */
u8 Lun; /* LUN (normally 0) */
u8 Length; /* Of the CDB, <= MAX_COMMAND_SIZE */
u8 CDB[16]; /* Command Data Block */
};
#define USB_BULK_CB_WRAP_LEN 31
#define USB_BULK_CB_SIG 0x43425355 /* Spells out USBC */
#define USB_BULK_IN_FLAG 0x80
/* Command Status Wrapper */
struct bulk_cs_wrap {
__le32 Signature; /* Should = 'USBS' */
u32 Tag; /* Same as original command */
__le32 Residue; /* Amount not transferred */
u8 Status; /* See below */
};
#define USB_BULK_CS_WRAP_LEN 13
#define USB_BULK_CS_SIG 0x53425355 /* Spells out 'USBS' */
#define USB_STATUS_PASS 0
#define USB_STATUS_FAIL 1
#define USB_STATUS_PHASE_ERROR 2
/* Bulk-only class specific requests */
#define USB_BULK_RESET_REQUEST 0xff
#define USB_BULK_GET_MAX_LUN_REQUEST 0xfe
/* CBI Interrupt data structure */
struct interrupt_data {
u8 bType;
u8 bValue;
};
#define CBI_INTERRUPT_DATA_LEN 2
/* CBI Accept Device-Specific Command request */
#define USB_CBI_ADSC_REQUEST 0x00
/* Length of a SCSI Command Data Block */
#define MAX_COMMAND_SIZE 16
/* SCSI commands that we recognize */
#define SC_FORMAT_UNIT 0x04
#define SC_INQUIRY 0x12
#define SC_MODE_SELECT_6 0x15
#define SC_MODE_SELECT_10 0x55
#define SC_MODE_SENSE_6 0x1a
#define SC_MODE_SENSE_10 0x5a
#define SC_PREVENT_ALLOW_MEDIUM_REMOVAL 0x1e
#define SC_READ_6 0x08
#define SC_READ_10 0x28
#define SC_READ_12 0xa8
#define SC_READ_CAPACITY 0x25
#define SC_READ_FORMAT_CAPACITIES 0x23
#define SC_READ_HEADER 0x44
#define SC_READ_TOC 0x43
#define SC_RELEASE 0x17
#define SC_REQUEST_SENSE 0x03
#define SC_RESERVE 0x16
#define SC_SEND_DIAGNOSTIC 0x1d
#define SC_START_STOP_UNIT 0x1b
#define SC_SYNCHRONIZE_CACHE 0x35
#define SC_TEST_UNIT_READY 0x00
#define SC_VERIFY 0x2f
#define SC_WRITE_6 0x0a
#define SC_WRITE_10 0x2a
#define SC_WRITE_12 0xaa
/* SCSI Sense Key/Additional Sense Code/ASC Qualifier values */
#define SS_NO_SENSE 0
#define SS_COMMUNICATION_FAILURE 0x040800
#define SS_INVALID_COMMAND 0x052000
#define SS_INVALID_FIELD_IN_CDB 0x052400
#define SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE 0x052100
#define SS_LOGICAL_UNIT_NOT_SUPPORTED 0x052500
#define SS_MEDIUM_NOT_PRESENT 0x023a00
#define SS_MEDIUM_REMOVAL_PREVENTED 0x055302
#define SS_NOT_READY_TO_READY_TRANSITION 0x062800
#define SS_RESET_OCCURRED 0x062900
#define SS_SAVING_PARAMETERS_NOT_SUPPORTED 0x053900
#define SS_UNRECOVERED_READ_ERROR 0x031100
#define SS_WRITE_ERROR 0x030c02
#define SS_WRITE_PROTECTED 0x072700
#define SK(x) ((u8) ((x) >> 16)) /* Sense Key byte, etc. */
#define ASC(x) ((u8) ((x) >> 8))
#define ASCQ(x) ((u8) (x))
/*-------------------------------------------------------------------------*/
struct fsg_lun {
struct file *filp;
loff_t file_length;
loff_t num_sectors;
unsigned int initially_ro:1;
unsigned int ro:1;
unsigned int removable:1;
unsigned int cdrom:1;
unsigned int prevent_medium_removal:1;
unsigned int registered:1;
unsigned int info_valid:1;
u32 sense_data;
u32 sense_data_info;
u32 unit_attention_data;
struct device dev;
};
#define fsg_lun_is_open(curlun) ((curlun)->filp != NULL)
static struct fsg_lun *fsg_lun_from_dev(struct device *dev)
{
return container_of(dev, struct fsg_lun, dev);
}
/* Big enough to hold our biggest descriptor */
#define EP0_BUFSIZE 256
#define DELAYED_STATUS (EP0_BUFSIZE + 999) /* An impossibly large value */
/* Number of buffers we will use. 2 is enough for double-buffering */
#define FSG_NUM_BUFFERS 2
/* Default size of buffer length. */
#define FSG_BUFLEN ((u32)16384)
/* Maximal number of LUNs supported in mass storage function */
#define FSG_MAX_LUNS 8
enum fsg_buffer_state {
BUF_STATE_EMPTY = 0,
BUF_STATE_FULL,
BUF_STATE_BUSY
};
struct fsg_buffhd {
#ifdef FSG_BUFFHD_STATIC_BUFFER
char buf[FSG_BUFLEN];
#else
void *buf;
#endif
enum fsg_buffer_state state;
struct fsg_buffhd *next;
/* The NetChip 2280 is faster, and handles some protocol faults
* better, if we don't submit any short bulk-out read requests.
* So we will record the intended request length here. */
unsigned int bulk_out_intended_length;
struct usb_request *inreq;
int inreq_busy;
struct usb_request *outreq;
int outreq_busy;
};
enum fsg_state {
/* This one isn't used anywhere */
FSG_STATE_COMMAND_PHASE = -10,
FSG_STATE_DATA_PHASE,
FSG_STATE_STATUS_PHASE,
FSG_STATE_IDLE = 0,
FSG_STATE_ABORT_BULK_OUT,
FSG_STATE_RESET,
FSG_STATE_INTERFACE_CHANGE,
FSG_STATE_CONFIG_CHANGE,
FSG_STATE_DISCONNECT,
FSG_STATE_EXIT,
FSG_STATE_TERMINATED
};
enum data_direction {
DATA_DIR_UNKNOWN = 0,
DATA_DIR_FROM_HOST,
DATA_DIR_TO_HOST,
DATA_DIR_NONE
};
/*-------------------------------------------------------------------------*/
static inline u32 get_unaligned_be24(u8 *buf)
{
return 0xffffff & (u32) get_unaligned_be32(buf - 1);
}
/*-------------------------------------------------------------------------*/
enum {
#ifndef FSG_NO_DEVICE_STRINGS
FSG_STRING_MANUFACTURER = 1,
FSG_STRING_PRODUCT,
FSG_STRING_SERIAL,
FSG_STRING_CONFIG,
#endif
FSG_STRING_INTERFACE
};
#ifndef FSG_NO_OTG
static struct usb_otg_descriptor
fsg_otg_desc = {
.bLength = sizeof fsg_otg_desc,
.bDescriptorType = USB_DT_OTG,
.bmAttributes = USB_OTG_SRP,
};
#endif
/* There is only one interface. */
static struct usb_interface_descriptor
fsg_intf_desc = {
.bLength = sizeof fsg_intf_desc,
.bDescriptorType = USB_DT_INTERFACE,
.bNumEndpoints = 2, /* Adjusted during fsg_bind() */
.bInterfaceClass = USB_CLASS_MASS_STORAGE,
.bInterfaceSubClass = USB_SC_SCSI, /* Adjusted during fsg_bind() */
.bInterfaceProtocol = USB_PR_BULK, /* Adjusted during fsg_bind() */
.iInterface = FSG_STRING_INTERFACE,
};
/* Three full-speed endpoint descriptors: bulk-in, bulk-out,
* and interrupt-in. */
static struct usb_endpoint_descriptor
fsg_fs_bulk_in_desc = {
.bLength = USB_DT_ENDPOINT_SIZE,
.bDescriptorType = USB_DT_ENDPOINT,
.bEndpointAddress = USB_DIR_IN,
.bmAttributes = USB_ENDPOINT_XFER_BULK,
/* wMaxPacketSize set by autoconfiguration */
};
static struct usb_endpoint_descriptor
fsg_fs_bulk_out_desc = {
.bLength = USB_DT_ENDPOINT_SIZE,
.bDescriptorType = USB_DT_ENDPOINT,
.bEndpointAddress = USB_DIR_OUT,
.bmAttributes = USB_ENDPOINT_XFER_BULK,
/* wMaxPacketSize set by autoconfiguration */
};
#ifndef FSG_NO_INTR_EP
static struct usb_endpoint_descriptor
fsg_fs_intr_in_desc = {
.bLength = USB_DT_ENDPOINT_SIZE,
.bDescriptorType = USB_DT_ENDPOINT,
.bEndpointAddress = USB_DIR_IN,
.bmAttributes = USB_ENDPOINT_XFER_INT,
.wMaxPacketSize = cpu_to_le16(2),
.bInterval = 32, /* frames -> 32 ms */
};
#ifndef FSG_NO_OTG
# define FSG_FS_FUNCTION_PRE_EP_ENTRIES 2
#else
# define FSG_FS_FUNCTION_PRE_EP_ENTRIES 1
#endif
#endif
static struct usb_descriptor_header *fsg_fs_function[] = {
#ifndef FSG_NO_OTG
(struct usb_descriptor_header *) &fsg_otg_desc,
#endif
(struct usb_descriptor_header *) &fsg_intf_desc,
(struct usb_descriptor_header *) &fsg_fs_bulk_in_desc,
(struct usb_descriptor_header *) &fsg_fs_bulk_out_desc,
#ifndef FSG_NO_INTR_EP
(struct usb_descriptor_header *) &fsg_fs_intr_in_desc,
#endif
NULL,
};
/*
* USB 2.0 devices need to expose both high speed and full speed
* descriptors, unless they only run at full speed.
*
* That means alternate endpoint descriptors (bigger packets)
* and a "device qualifier" ... plus more construction options
* for the config descriptor.
*/
static struct usb_endpoint_descriptor
fsg_hs_bulk_in_desc = {
.bLength = USB_DT_ENDPOINT_SIZE,
.bDescriptorType = USB_DT_ENDPOINT,
/* bEndpointAddress copied from fs_bulk_in_desc during fsg_bind() */
.bmAttributes = USB_ENDPOINT_XFER_BULK,
.wMaxPacketSize = cpu_to_le16(512),
};
static struct usb_endpoint_descriptor
fsg_hs_bulk_out_desc = {
.bLength = USB_DT_ENDPOINT_SIZE,
.bDescriptorType = USB_DT_ENDPOINT,
/* bEndpointAddress copied from fs_bulk_out_desc during fsg_bind() */
.bmAttributes = USB_ENDPOINT_XFER_BULK,
.wMaxPacketSize = cpu_to_le16(512),
.bInterval = 1, /* NAK every 1 uframe */
};
#ifndef FSG_NO_INTR_EP
static struct usb_endpoint_descriptor
fsg_hs_intr_in_desc = {
.bLength = USB_DT_ENDPOINT_SIZE,
.bDescriptorType = USB_DT_ENDPOINT,
/* bEndpointAddress copied from fs_intr_in_desc during fsg_bind() */
.bmAttributes = USB_ENDPOINT_XFER_INT,
.wMaxPacketSize = cpu_to_le16(2),
.bInterval = 9, /* 2**(9-1) = 256 uframes -> 32 ms */
};
#ifndef FSG_NO_OTG
# define FSG_HS_FUNCTION_PRE_EP_ENTRIES 2
#else
# define FSG_HS_FUNCTION_PRE_EP_ENTRIES 1
#endif
#endif
static struct usb_descriptor_header *fsg_hs_function[] = {
#ifndef FSG_NO_OTG
(struct usb_descriptor_header *) &fsg_otg_desc,
#endif
(struct usb_descriptor_header *) &fsg_intf_desc,
(struct usb_descriptor_header *) &fsg_hs_bulk_in_desc,
(struct usb_descriptor_header *) &fsg_hs_bulk_out_desc,
#ifndef FSG_NO_INTR_EP
(struct usb_descriptor_header *) &fsg_hs_intr_in_desc,
#endif
NULL,
};
/* Maxpacket and other transfer characteristics vary by speed. */
static struct usb_endpoint_descriptor *
fsg_ep_desc(struct usb_gadget *g, struct usb_endpoint_descriptor *fs,
struct usb_endpoint_descriptor *hs)
{
if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH)
return hs;
return fs;
}
/* Static strings, in UTF-8 (for simplicity we use only ASCII characters) */
static struct usb_string fsg_strings[] = {
#ifndef FSG_NO_DEVICE_STRINGS
{FSG_STRING_MANUFACTURER, fsg_string_manufacturer},
{FSG_STRING_PRODUCT, fsg_string_product},
{FSG_STRING_SERIAL, fsg_string_serial},
{FSG_STRING_CONFIG, fsg_string_config},
#endif
{FSG_STRING_INTERFACE, fsg_string_interface},
{}
};
static struct usb_gadget_strings fsg_stringtab = {
.language = 0x0409, /* en-us */
.strings = fsg_strings,
};
/*-------------------------------------------------------------------------*/
/* If the next two routines are called while the gadget is registered,
* the caller must own fsg->filesem for writing. */
static int fsg_lun_open(struct fsg_lun *curlun, const char *filename)
{
int ro;
struct file *filp = NULL;
int rc = -EINVAL;
struct inode *inode = NULL;
loff_t size;
loff_t num_sectors;
loff_t min_sectors;
/* R/W if we can, R/O if we must */
ro = curlun->initially_ro;
if (!ro) {
filp = filp_open(filename, O_RDWR | O_LARGEFILE, 0);
if (-EROFS == PTR_ERR(filp))
ro = 1;
}
if (ro)
filp = filp_open(filename, O_RDONLY | O_LARGEFILE, 0);
if (IS_ERR(filp)) {
LINFO(curlun, "unable to open backing file: %s\n", filename);
return PTR_ERR(filp);
}
if (!(filp->f_mode & FMODE_WRITE))
ro = 1;
if (filp->f_path.dentry)
inode = filp->f_path.dentry->d_inode;
if (inode && S_ISBLK(inode->i_mode)) {
if (bdev_read_only(inode->i_bdev))
ro = 1;
} else if (!inode || !S_ISREG(inode->i_mode)) {
LINFO(curlun, "invalid file type: %s\n", filename);
goto out;
}
/* If we can't read the file, it's no good.
* If we can't write the file, use it read-only. */
if (!filp->f_op || !(filp->f_op->read || filp->f_op->aio_read)) {
LINFO(curlun, "file not readable: %s\n", filename);
goto out;
}
if (!(filp->f_op->write || filp->f_op->aio_write))
ro = 1;
size = i_size_read(inode->i_mapping->host);
if (size < 0) {
LINFO(curlun, "unable to find file size: %s\n", filename);
rc = (int) size;
goto out;
}
num_sectors = size >> 9; /* File size in 512-byte blocks */
min_sectors = 1;
if (curlun->cdrom) {
num_sectors &= ~3; /* Reduce to a multiple of 2048 */
min_sectors = 300*4; /* Smallest track is 300 frames */
if (num_sectors >= 256*60*75*4) {
num_sectors = (256*60*75 - 1) * 4;
LINFO(curlun, "file too big: %s\n", filename);
LINFO(curlun, "using only first %d blocks\n",
(int) num_sectors);
}
}
if (num_sectors < min_sectors) {
LINFO(curlun, "file too small: %s\n", filename);
rc = -ETOOSMALL;
goto out;
}
get_file(filp);
curlun->ro = ro;
curlun->filp = filp;
curlun->file_length = size;
curlun->num_sectors = num_sectors;
LDBG(curlun, "open backing file: %s\n", filename);
rc = 0;
out:
filp_close(filp, current->files);
return rc;
}
static void fsg_lun_close(struct fsg_lun *curlun)
{
if (curlun->filp) {
LDBG(curlun, "close backing file\n");
fput(curlun->filp);
curlun->filp = NULL;
}
}
/*-------------------------------------------------------------------------*/
/* Sync the file data, don't bother with the metadata.
* This code was copied from fs/buffer.c:sys_fdatasync(). */
static int fsg_lun_fsync_sub(struct fsg_lun *curlun)
{
struct file *filp = curlun->filp;
if (curlun->ro || !filp)
return 0;
return vfs_fsync(filp, 1);
}
static void store_cdrom_address(u8 *dest, int msf, u32 addr)
{
if (msf) {
/* Convert to Minutes-Seconds-Frames */
addr >>= 2; /* Convert to 2048-byte frames */
addr += 2*75; /* Lead-in occupies 2 seconds */
dest[3] = addr % 75; /* Frames */
addr /= 75;
dest[2] = addr % 60; /* Seconds */
addr /= 60;
dest[1] = addr; /* Minutes */
dest[0] = 0; /* Reserved */
} else {
/* Absolute sector */
put_unaligned_be32(addr, dest);
}
}
/*-------------------------------------------------------------------------*/
static ssize_t fsg_show_ro(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct fsg_lun *curlun = fsg_lun_from_dev(dev);
return sprintf(buf, "%d\n", fsg_lun_is_open(curlun)
? curlun->ro
: curlun->initially_ro);
}
static ssize_t fsg_show_file(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct fsg_lun *curlun = fsg_lun_from_dev(dev);
struct rw_semaphore *filesem = dev_get_drvdata(dev);
char *p;
ssize_t rc;
down_read(filesem);
if (fsg_lun_is_open(curlun)) { /* Get the complete pathname */
p = d_path(&curlun->filp->f_path, buf, PAGE_SIZE - 1);
if (IS_ERR(p))
rc = PTR_ERR(p);
else {
rc = strlen(p);
memmove(buf, p, rc);
buf[rc] = '\n'; /* Add a newline */
buf[++rc] = 0;
}
} else { /* No file, return 0 bytes */
*buf = 0;
rc = 0;
}
up_read(filesem);
return rc;
}
static ssize_t fsg_store_ro(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
ssize_t rc = count;
struct fsg_lun *curlun = fsg_lun_from_dev(dev);
struct rw_semaphore *filesem = dev_get_drvdata(dev);
int i;
if (sscanf(buf, "%d", &i) != 1)
return -EINVAL;
/* Allow the write-enable status to change only while the backing file
* is closed. */
down_read(filesem);
if (fsg_lun_is_open(curlun)) {
LDBG(curlun, "read-only status change prevented\n");
rc = -EBUSY;
} else {
curlun->ro = !!i;
curlun->initially_ro = !!i;
LDBG(curlun, "read-only status set to %d\n", curlun->ro);
}
up_read(filesem);
return rc;
}
static ssize_t fsg_store_file(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct fsg_lun *curlun = fsg_lun_from_dev(dev);
struct rw_semaphore *filesem = dev_get_drvdata(dev);
int rc = 0;
if (curlun->prevent_medium_removal && fsg_lun_is_open(curlun)) {
LDBG(curlun, "eject attempt prevented\n");
return -EBUSY; /* "Door is locked" */
}
/* Remove a trailing newline */
if (count > 0 && buf[count-1] == '\n')
((char *) buf)[count-1] = 0; /* Ugh! */
/* Eject current medium */
down_write(filesem);
if (fsg_lun_is_open(curlun)) {
fsg_lun_close(curlun);
curlun->unit_attention_data = SS_MEDIUM_NOT_PRESENT;
}
/* Load new medium */
if (count > 0 && buf[0]) {
rc = fsg_lun_open(curlun, buf);
if (rc == 0)
curlun->unit_attention_data =
SS_NOT_READY_TO_READY_TRANSITION;
}
up_write(filesem);
return (rc < 0 ? rc : count);
}
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