* function for a USB device, it also illustrates a technique of
* double-buffering for increased throughput.
*
- * Function supports multiple logical units (LUNs). Backing storage
- * for each LUN is provided by a regular file or a block device.
- * Access for each LUN can be limited to read-only. Moreover, the
- * function can indicate that LUN is removable and/or CD-ROM. (The
- * later implies read-only access.)
- *
+ * For more information about MSF and in particular its module
+ * parameters and sysfs interface read the
+ * <Documentation/usb/mass-storage.txt> file.
+ */
+
+/*
* MSF is configured by specifying a fsg_config structure. It has the
* following fields:
*
* data track and no audio tracks; hence there need be only one
* backing file per LUN.
*
- *
- * MSF includes support for module parameters. If gadget using it
- * decides to use it, the following module parameters will be
- * available:
- *
- * file=filename[,filename...]
- * Names of the files or block devices used for
- * backing storage.
- * ro=b[,b...] Default false, boolean for read-only access.
- * removable=b[,b...]
- * Default false, boolean for removable media.
- * cdrom=b[,b...] Default false, boolean for whether to emulate
- * a CD-ROM drive.
- * nofua=b[,b...] Default false, booleans for ignore FUA flag
- * in SCSI WRITE(10,12) commands
- * luns=N Default N = number of filenames, number of
- * LUNs to support.
- * stall Default determined according to the type of
- * USB device controller (usually true),
- * boolean to permit the driver to halt
- * bulk endpoints.
- *
- * The module parameters may be prefixed with some string. You need
- * to consult gadget's documentation or source to verify whether it is
- * using those module parameters and if it does what are the prefixes
- * (look for FSG_MODULE_PARAMETERS() macro usage, what's inside it is
- * the prefix).
- *
- *
- * Requirements are modest; only a bulk-in and a bulk-out endpoint are
- * needed. The memory requirement amounts to two 16K buffers, size
- * configurable by a parameter. Support is included for both
- * full-speed and high-speed operation.
- *
- * Note that the driver is slightly non-portable in that it assumes a
- * single memory/DMA buffer will be useable for bulk-in, bulk-out, and
- * interrupt-in endpoints. With most device controllers this isn't an
- * issue, but there may be some with hardware restrictions that prevent
- * a buffer from being used by more than one endpoint.
- *
- *
- * The pathnames of the backing files, the ro settings and nofua
- * settings are available in the attribute files "file", "ro" and
- * "nofua" in the lun<n> subdirectory of the gadget's sysfs directory.
- * If the "removable" option is set, writing to these files will
- * simulate ejecting/loading the medium (writing an empty line means
- * eject) and adjusting a write-enable tab. Changes to the ro setting
- * are not allowed when the medium is loaded or if CD-ROM emulation is
- * being used.
- *
- * When a LUN receive an "eject" SCSI request (Start/Stop Unit),
- * if the LUN is removable, the backing file is released to simulate
- * ejection.
- *
- *
* This function is heavily based on "File-backed Storage Gadget" by
* Alan Stern which in turn is heavily based on "Gadget Zero" by David
* Brownell. The driver's SCSI command interface was based on the
* In normal operation the main thread is started during the gadget's
* fsg_bind() callback and stopped during fsg_unbind(). But it can
* also exit when it receives a signal, and there's no point leaving
- * the gadget running when the thread is dead. At of this moment, MSF
+ * the gadget running when the thread is dead. As of this moment, MSF
* provides no way to deregister the gadget when thread dies -- maybe
* a callback functions is needed.
*
/*************************** DEVICE ATTRIBUTES ***************************/
-/* Write permission is checked per LUN in store_*() functions. */
static DEVICE_ATTR(ro, 0644, fsg_show_ro, fsg_store_ro);
static DEVICE_ATTR(nofua, 0644, fsg_show_nofua, fsg_store_nofua);
static DEVICE_ATTR(file, 0644, fsg_show_file, fsg_store_file);
+static struct device_attribute dev_attr_ro_cdrom =
+ __ATTR(ro, 0444, fsg_show_ro, NULL);
+static struct device_attribute dev_attr_file_nonremovable =
+ __ATTR(file, 0444, fsg_show_file, NULL);
+
/****************************** FSG COMMON ******************************/
goto error_release;
}
- rc = device_create_file(&curlun->dev, &dev_attr_ro);
+ rc = device_create_file(&curlun->dev,
+ curlun->cdrom
+ ? &dev_attr_ro_cdrom
+ : &dev_attr_ro);
if (rc)
goto error_luns;
- rc = device_create_file(&curlun->dev, &dev_attr_file);
+ rc = device_create_file(&curlun->dev,
+ curlun->removable
+ ? &dev_attr_file
+ : &dev_attr_file_nonremovable);
if (rc)
goto error_luns;
rc = device_create_file(&curlun->dev, &dev_attr_nofua);
/* In error recovery common->nluns may be zero. */
for (; i; --i, ++lun) {
device_remove_file(&lun->dev, &dev_attr_nofua);
- device_remove_file(&lun->dev, &dev_attr_ro);
- device_remove_file(&lun->dev, &dev_attr_file);
+ device_remove_file(&lun->dev,
+ lun->cdrom
+ ? &dev_attr_ro_cdrom
+ : &dev_attr_ro);
+ device_remove_file(&lun->dev,
+ lun->removable
+ ? &dev_attr_file
+ : &dev_attr_file_nonremovable);
fsg_lun_close(lun);
device_unregister(&lun->dev);
}
projects / platform / adaptation / renesas_rcar / renesas_kernel.git / blobdiff