diff options
Diffstat (limited to 'drivers/usb/gadget')
-rw-r--r-- | drivers/usb/gadget/f_mass_storage.c | 69 |
1 files changed, 7 insertions, 62 deletions
diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c index 9b29e8e..7ad4f81 100644 --- a/drivers/usb/gadget/f_mass_storage.c +++ b/drivers/usb/gadget/f_mass_storage.c @@ -44,12 +44,12 @@ * 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: * @@ -95,61 +95,6 @@ * 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 @@ -191,7 +136,7 @@ * 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. * |