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path: root/drivers/usb/gadget/storage_common.c
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Diffstat (limited to 'drivers/usb/gadget/storage_common.c')
-rw-r--r--drivers/usb/gadget/storage_common.c704
1 files changed, 704 insertions, 0 deletions
diff --git a/drivers/usb/gadget/storage_common.c b/drivers/usb/gadget/storage_common.c
new file mode 100644
index 00000000..26636648
--- /dev/null
+++ b/drivers/usb/gadget/storage_common.c
@@ -0,0 +1,704 @@
+/*
+ * storage_common.c -- Common definitions for mass storage functionality
+ *
+ * Copyright (C) 2003-2008 Alan Stern
+ * Copyeight (C) 2009 Samsung Electronics
+ * Author: Michal Nazarewicz (mina86@mina86.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 file requires the following identifiers used in USB strings to
+ * be defined (each of type pointer to char):
+ * - fsg_string_interface -- name of the interface
+ */
+
+/*
+ * When USB_GADGET_DEBUG_FILES is defined the module param num_buffers
+ * sets the number of pipeline buffers (length of the fsg_buffhd array).
+ * The valid range of num_buffers is: num >= 2 && num <= 4.
+ */
+
+
+#include <linux/usb/storage.h>
+#include <scsi/scsi.h>
+#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)
+
+
+#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 */
+
+/*-------------------------------------------------------------------------*/
+
+/* Length of a SCSI Command Data Block */
+#define MAX_COMMAND_SIZE 16
+
+/* 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;
+ unsigned int nofua:1;
+
+ u32 sense_data;
+ u32 sense_data_info;
+ u32 unit_attention_data;
+
+ unsigned int blkbits; /* Bits of logical block size of bound block device */
+ unsigned int blksize; /* logical block size of bound block device */
+ struct device dev;
+};
+
+static inline bool fsg_lun_is_open(struct fsg_lun *curlun)
+{
+ return curlun->filp != NULL;
+}
+
+static inline 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 */
+
+#ifdef CONFIG_USB_GADGET_DEBUG_FILES
+
+static unsigned int fsg_num_buffers = CONFIG_USB_GADGET_STORAGE_NUM_BUFFERS;
+module_param_named(num_buffers, fsg_num_buffers, uint, S_IRUGO);
+MODULE_PARM_DESC(num_buffers, "Number of pipeline buffers");
+
+#else
+
+/*
+ * Number of buffers we will use.
+ * 2 is usually enough for good buffering pipeline
+ */
+#define fsg_num_buffers CONFIG_USB_GADGET_STORAGE_NUM_BUFFERS
+
+#endif /* CONFIG_USB_DEBUG */
+
+/* check if fsg_num_buffers is within a valid range */
+static inline int fsg_num_buffers_validate(void)
+{
+ if (fsg_num_buffers >= 2 && fsg_num_buffers <= 4)
+ return 0;
+ pr_err("fsg_num_buffers %u is out of range (%d to %d)\n",
+ fsg_num_buffers, 2 ,4);
+ return -EINVAL;
+}
+
+/* Default size of buffer length. */
+#define FSG_BUFLEN ((u32)32768)
+
+/* 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 {
+ void *buf;
+ 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 {
+ FSG_STRING_INTERFACE
+};
+
+
+/* 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 */
+};
+
+static struct usb_descriptor_header *fsg_fs_function[] = {
+ (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,
+ 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 configuration 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 */
+};
+
+
+static struct usb_descriptor_header *fsg_hs_function[] = {
+ (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,
+ NULL,
+};
+
+static struct usb_endpoint_descriptor
+fsg_ss_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(1024),
+};
+
+static struct usb_ss_ep_comp_descriptor fsg_ss_bulk_in_comp_desc = {
+ .bLength = sizeof(fsg_ss_bulk_in_comp_desc),
+ .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
+
+ /*.bMaxBurst = DYNAMIC, */
+};
+
+static struct usb_endpoint_descriptor
+fsg_ss_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(1024),
+};
+
+static struct usb_ss_ep_comp_descriptor fsg_ss_bulk_out_comp_desc = {
+ .bLength = sizeof(fsg_ss_bulk_in_comp_desc),
+ .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
+
+ /*.bMaxBurst = DYNAMIC, */
+};
+
+static struct usb_descriptor_header *fsg_ss_function[] = {
+ (struct usb_descriptor_header *) &fsg_intf_desc,
+ (struct usb_descriptor_header *) &fsg_ss_bulk_in_desc,
+ (struct usb_descriptor_header *) &fsg_ss_bulk_in_comp_desc,
+ (struct usb_descriptor_header *) &fsg_ss_bulk_out_desc,
+ (struct usb_descriptor_header *) &fsg_ss_bulk_out_comp_desc,
+ NULL,
+};
+
+/* Static strings, in UTF-8 (for simplicity we use only ASCII characters) */
+static struct usb_string fsg_strings[] = {
+ {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 void fsg_lun_close(struct fsg_lun *curlun)
+{
+ if (curlun->filp) {
+ LDBG(curlun, "close backing file\n");
+ fput(curlun->filp);
+ curlun->filp = NULL;
+ }
+}
+
+
+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;
+ unsigned int blkbits;
+ unsigned int blksize;
+
+ /* 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 (PTR_ERR(filp) == -EROFS || PTR_ERR(filp) == -EACCES)
+ 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;
+
+ inode = file_inode(filp);
+ if ((!S_ISREG(inode->i_mode) && !S_ISBLK(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->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;
+ }
+
+ blksize = 512;
+ blkbits = 9;
+
+
+ num_sectors = size >> blkbits; /* File size in logic-block-size 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;
+ }
+
+ if (fsg_lun_is_open(curlun))
+ fsg_lun_close(curlun);
+
+ curlun->blksize = blksize;
+ curlun->blkbits = blkbits;
+ curlun->ro = ro;
+ curlun->filp = filp;
+ curlun->file_length = size;
+ curlun->num_sectors = num_sectors;
+ LINFO(curlun, "open backing file: %s\n", filename);
+ return 0;
+
+out:
+ fput(filp);
+ return rc;
+}
+
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * 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_nofua(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct fsg_lun *curlun = fsg_lun_from_dev(dev);
+
+ return sprintf(buf, "%u\n", curlun->nofua);
+}
+
+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;
+ struct fsg_lun *curlun = fsg_lun_from_dev(dev);
+ struct rw_semaphore *filesem = dev_get_drvdata(dev);
+ unsigned ro;
+
+ rc = kstrtouint(buf, 2, &ro);
+ if (rc)
+ return rc;
+
+ /*
+ * 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 = ro;
+ curlun->initially_ro = ro;
+ LDBG(curlun, "read-only status set to %d\n", curlun->ro);
+ rc = count;
+ }
+ up_read(filesem);
+ return rc;
+}
+
+static ssize_t fsg_store_nofua(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct fsg_lun *curlun = fsg_lun_from_dev(dev);
+ unsigned nofua;
+ int ret;
+
+ ret = kstrtouint(buf, 2, &nofua);
+ if (ret)
+ return ret;
+
+ /* Sync data when switching from async mode to sync */
+ if (!nofua && curlun->nofua)
+ fsg_lun_fsync_sub(curlun);
+
+ curlun->nofua = nofua;
+
+ return count;
+}
+
+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;
+
+ /* Remove a trailing newline */
+ if (count > 0 && buf[count-1] == '\n')
+ ((char *) buf)[count-1] = 0; /* Ugh! */
+
+ down_write(filesem);
+ /* Eject current medium */
+ 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]) {
+ /* fsg_lun_open() will close existing file if any. */
+ 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);
+}
+static ssize_t fsg_show_cdrom(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct fsg_lun *curlun = fsg_lun_from_dev(dev);
+
+ return sprintf(buf, "%d\n", curlun->cdrom);
+}
+static ssize_t fsg_store_cdrom(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ ssize_t rc;
+ struct fsg_lun *curlun = fsg_lun_from_dev(dev);
+ struct rw_semaphore *filesem = dev_get_drvdata(dev);
+ unsigned cdrom;
+
+ if (sscanf(buf, "%d", &cdrom) != 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->cdrom = cdrom;
+ LDBG(curlun, "file storage set to cdrom: %d\n", curlun->cdrom);
+ rc = count;
+ }
+ up_read(filesem);
+ return rc;
+}
+
generated by cgit v1.3.1 (git 2.54.0) at 2026-08-15 17:25:16 +0000