// SPDX-License-Identifier: GPL-2.0+
/*
 * mass_storage.c -- Mass Storage USB Gadget
 *
 * Copyright (C) 2003-2008 Alan Stern
 * Copyright (C) 2009 Samsung Electronics
 *                    Author: Michal Nazarewicz <mina86@mina86.com>
 * All rights reserved.
 */


/*
 * 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"

/*
 * 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 */

#include "f_mass_storage.h"

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

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

	/* .bcdUSB = DYNAMIC */
	.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 const struct usb_descriptor_header *otg_desc[2];

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,
};

static struct usb_function_instance *fi_msg;
static struct usb_function *f_msg;

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

static struct fsg_module_parameters mod_data = {
	.stall = 1
};
#ifdef CONFIG_USB_GADGET_DEBUG_FILES

static unsigned int fsg_num_buffers = CONFIG_USB_GADGET_STORAGE_NUM_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_GADGET_DEBUG_FILES */

FSG_MODULE_PARAMETERS(/* no prefix */, mod_data);

static int msg_do_config(struct usb_configuration *c)
{
	int ret;

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

	f_msg = usb_get_function(fi_msg);
	if (IS_ERR(f_msg))
		return PTR_ERR(f_msg);

	ret = usb_add_function(c, f_msg);
	if (ret)
		goto put_func;

	return 0;

put_func:
	usb_put_function(f_msg);
	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 msg_bind(struct usb_composite_dev *cdev)
{
	struct fsg_opts *opts;
	struct fsg_config config;
	int status;

	fi_msg = usb_get_function_instance("mass_storage");
	if (IS_ERR(fi_msg))
		return PTR_ERR(fi_msg);

	fsg_config_from_params(&config, &mod_data, fsg_num_buffers);
	opts = fsg_opts_from_func_inst(fi_msg);

	opts->no_configfs = true;
	status = fsg_common_set_num_buffers(opts->common, fsg_num_buffers);
	if (status)
		goto fail;

	status = fsg_common_set_cdev(opts->common, cdev, config.can_stall);
	if (status)
		goto fail_set_cdev;

	fsg_common_set_sysfs(opts->common, true);
	status = fsg_common_create_luns(opts->common, &config);
	if (status)
		goto fail_set_cdev;

	fsg_common_set_inquiry_string(opts->common, config.vendor_name,
				      config.product_name);

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

	if (gadget_is_otg(cdev->gadget) && !otg_desc[0]) {
		struct usb_descriptor_header *usb_desc;

		usb_desc = usb_otg_descriptor_alloc(cdev->gadget);
		if (!usb_desc) {
			status = -ENOMEM;
			goto fail_string_ids;
		}
		usb_otg_descriptor_init(cdev->gadget, usb_desc);
		otg_desc[0] = usb_desc;
		otg_desc[1] = NULL;
	}

	status = usb_add_config(cdev, &msg_config_driver, msg_do_config);
	if (status < 0)
		goto fail_otg_desc;

	usb_composite_overwrite_options(cdev, &coverwrite);
	dev_info(&cdev->gadget->dev,
		 DRIVER_DESC ", version: " DRIVER_VERSION "\n");
	return 0;

fail_otg_desc:
	kfree(otg_desc[0]);
	otg_desc[0] = NULL;
fail_string_ids:
	fsg_common_remove_luns(opts->common);
fail_set_cdev:
	fsg_common_free_buffers(opts->common);
fail:
	usb_put_function_instance(fi_msg);
	return status;
}

static int msg_unbind(struct usb_composite_dev *cdev)
{
	if (!IS_ERR(f_msg))
		usb_put_function(f_msg);

	if (!IS_ERR(fi_msg))
		usb_put_function_instance(fi_msg);

	kfree(otg_desc[0]);
	otg_desc[0] = NULL;

	return 0;
}

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

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

module_usb_composite_driver(msg_driver);

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