mass_storage.c

Go to the documentation of this file.

/*
 * mass_storage.c -- Mass Storage USB Gadget
 *
 * Copyright (C) 2003-2008 Alan Stern
 * Copyright (C) 2009 Samsung Electronics
 *                    Author: Michal Nazarewicz <[email protected]>
 * All rights reserved.
 *
 * 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.
 */


/*
 * The Mass Storage Gadget acts as a USB Mass Storage device,
 * appearing to the host as a disk drive or as a CD-ROM drive.  In
 * addition to providing an example of a genuinely useful gadget
 * driver for a USB device, it also illustrates a technique of
 * double-buffering for increased throughput.  Last but not least, it
 * gives an easy way to probe the behavior of the Mass Storage drivers
 * in a USB host.
 *
 * Since this file serves only administrative purposes and all the
 * business logic is implemented in f_mass_storage.* file.  Read
 * comments in this file for more detailed description.
 */


#include <linux/kernel.h>
#include <linux/usb/ch9.h>
#include <linux/module.h>

/*-------------------------------------------------------------------------*/

#define DRIVER_DESC     "Mass Storage Gadget"
#define DRIVER_VERSION      "2009/09/11"

/*-------------------------------------------------------------------------*/

/*
 * kbuild is not very cooperative with respect to linking separately
 * compiled library objects into one module.  So for now we won't use
 * separate compilation ... ensuring init/exit sections work to shrink
 * the runtime footprint, and giving us at least some parts of what
 * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
 */
#include "f_mass_storage.c"

/*-------------------------------------------------------------------------*/
USB_GADGET_COMPOSITE_OPTIONS();

static struct usb_device_descriptor msg_device_desc = {
    .bLength =      sizeof msg_device_desc,
    .bDescriptorType =  USB_DT_DEVICE,

    .bcdUSB =       cpu_to_le16(0x0200),
    .bDeviceClass =     USB_CLASS_PER_INTERFACE,

    /* Vendor and product id can be overridden by module parameters.  */
    .idVendor =     cpu_to_le16(FSG_VENDOR_ID),
    .idProduct =        cpu_to_le16(FSG_PRODUCT_ID),
    .bNumConfigurations =   1,
};

static struct usb_otg_descriptor otg_descriptor = {
    .bLength =      sizeof otg_descriptor,
    .bDescriptorType =  USB_DT_OTG,

    /*
     * REVISIT SRP-only hardware is possible, although
     * it would not be called "OTG" ...
     */
    .bmAttributes =     USB_OTG_SRP | USB_OTG_HNP,
};

static const struct usb_descriptor_header *otg_desc[] = {
    (struct usb_descriptor_header *) &otg_descriptor,
    NULL,
};

static struct usb_string strings_dev[] = {
    [USB_GADGET_MANUFACTURER_IDX].s = "",
    [USB_GADGET_PRODUCT_IDX].s = DRIVER_DESC,
    [USB_GADGET_SERIAL_IDX].s = "",
    {  } /* end of list */
};

static struct usb_gadget_strings stringtab_dev = {
    .language       = 0x0409,       /* en-us */
    .strings        = strings_dev,
};

static struct usb_gadget_strings *dev_strings[] = {
    &stringtab_dev,
    NULL,
};

/****************************** Configurations ******************************/

static struct fsg_module_parameters mod_data = {
    .stall = 1
};
FSG_MODULE_PARAMETERS(/* no prefix */, mod_data);

static unsigned long msg_registered;
static void msg_cleanup(void);

static int msg_thread_exits(struct fsg_common *common)
{
    msg_cleanup();
    return 0;
}

static int __init msg_do_config(struct usb_configuration *c)
{
    static const struct fsg_operations ops = {
        .thread_exits = msg_thread_exits,
    };
    static struct fsg_common common;

    struct fsg_common *retp;
    struct fsg_config config;
    int ret;

    if (gadget_is_otg(c->cdev->gadget)) {
        c->descriptors = otg_desc;
        c->bmAttributes |= USB_CONFIG_ATT_WAKEUP;
    }

    fsg_config_from_params(&config, &mod_data);
    config.ops = &ops;

    retp = fsg_common_init(&common, c->cdev, &config);
    if (IS_ERR(retp))
        return PTR_ERR(retp);

    ret = fsg_bind_config(c->cdev, c, &common);
    fsg_common_put(&common);
    return ret;
}

static struct usb_configuration msg_config_driver = {
    .label          = "Linux File-Backed Storage",
    .bConfigurationValue    = 1,
    .bmAttributes       = USB_CONFIG_ATT_SELFPOWER,
};


/****************************** Gadget Bind ******************************/

static int __init msg_bind(struct usb_composite_dev *cdev)
{
    int status;

    status = usb_string_ids_tab(cdev, strings_dev);
    if (status < 0)
        return status;
    msg_device_desc.iProduct = strings_dev[USB_GADGET_PRODUCT_IDX].id;

    status = usb_add_config(cdev, &msg_config_driver, msg_do_config);
    if (status < 0)
        return status;
    usb_composite_overwrite_options(cdev, &coverwrite);
    dev_info(&cdev->gadget->dev,
         DRIVER_DESC ", version: " DRIVER_VERSION "\n");
    set_bit(0, &msg_registered);
    return 0;
}


/****************************** Some noise ******************************/

static __refdata struct usb_composite_driver msg_driver = {
    .name       = "g_mass_storage",
    .dev        = &msg_device_desc,
    .max_speed  = USB_SPEED_SUPER,
    .needs_serial   = 1,
    .strings    = dev_strings,
    .bind       = msg_bind,
};

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_AUTHOR("Michal Nazarewicz");
MODULE_LICENSE("GPL");

static int __init msg_init(void)
{
    return usb_composite_probe(&msg_driver);
}
module_init(msg_init);

static void msg_cleanup(void)
{
    if (test_and_clear_bit(0, &msg_registered))
        usb_composite_unregister(&msg_driver);
}
module_exit(msg_cleanup);