// SPDX-License-Identifier: GPL-2.0
/* Target based USB-Gadget
 *
 * UAS protocol handling, target callbacks, configfs handling,
 * BBB (USB Mass Storage Class Bulk-Only (BBB) and Transport protocol handling.
 *
 * Author: Sebastian Andrzej Siewior <bigeasy at linutronix dot de>
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/configfs.h>
#include <linux/ctype.h>
#include <linux/usb/ch9.h>
#include <linux/usb/composite.h>
#include <linux/usb/gadget.h>
#include <linux/usb/storage.h>
#include <scsi/scsi_tcq.h>
#include <target/target_core_base.h>
#include <target/target_core_fabric.h>
#include <linux/unaligned.h>

#include "u_tcm.h"

USB_GADGET_COMPOSITE_OPTIONS();

#define UAS_VENDOR_ID   0x0525  /* NetChip */
#define UAS_PRODUCT_ID  0xa4a5  /* Linux-USB File-backed Storage Gadget */

static struct usb_device_descriptor usbg_device_desc = {
        .bLength =              sizeof(usbg_device_desc),
        .bDescriptorType =      USB_DT_DEVICE,
        /* .bcdUSB = DYNAMIC */
        .bDeviceClass =         USB_CLASS_PER_INTERFACE,
        .idVendor =             cpu_to_le16(UAS_VENDOR_ID),
        .idProduct =            cpu_to_le16(UAS_PRODUCT_ID),
        .bNumConfigurations =   1,
};

#define USB_G_STR_CONFIG USB_GADGET_FIRST_AVAIL_IDX

static struct usb_string        usbg_us_strings[] = {
        [USB_GADGET_MANUFACTURER_IDX].s = "Target Manufacturer",
        [USB_GADGET_PRODUCT_IDX].s      = "Target Product",
        [USB_GADGET_SERIAL_IDX].s       = "000000000001",
        [USB_G_STR_CONFIG].s            = "default config",
        { },
};

static struct usb_gadget_strings usbg_stringtab = {
        .language = 0x0409,
        .strings = usbg_us_strings,
};

static struct usb_gadget_strings *usbg_strings[] = {
        &usbg_stringtab,
        NULL,
};

static struct usb_function_instance *fi_tcm;
static struct usb_function *f_tcm;

static int guas_unbind(struct usb_composite_dev *cdev)
{
        if (!IS_ERR_OR_NULL(f_tcm))
                usb_put_function(f_tcm);

        return 0;
}

static int tcm_do_config(struct usb_configuration *c)
{
        int status;

        f_tcm = usb_get_function(fi_tcm);
        if (IS_ERR(f_tcm))
                return PTR_ERR(f_tcm);

        status = usb_add_function(c, f_tcm);
        if (status < 0) {
                usb_put_function(f_tcm);
                return status;
        }

        return 0;
}

static struct usb_configuration usbg_config_driver = {
        .label                  = "Linux Target",
        .bConfigurationValue    = 1,
        .bmAttributes           = USB_CONFIG_ATT_SELFPOWER,
};

static int usbg_attach(struct usb_function_instance *f);
static void usbg_detach(struct usb_function_instance *f);

static int usb_target_bind(struct usb_composite_dev *cdev)
{
        int ret;

        ret = usb_string_ids_tab(cdev, usbg_us_strings);
        if (ret)
                return ret;

        usbg_device_desc.iManufacturer =
                usbg_us_strings[USB_GADGET_MANUFACTURER_IDX].id;
        usbg_device_desc.iProduct = usbg_us_strings[USB_GADGET_PRODUCT_IDX].id;
        usbg_device_desc.iSerialNumber =
                usbg_us_strings[USB_GADGET_SERIAL_IDX].id;
        usbg_config_driver.iConfiguration =
                usbg_us_strings[USB_G_STR_CONFIG].id;

        ret = usb_add_config(cdev, &usbg_config_driver, tcm_do_config);
        if (ret)
                return ret;
        usb_composite_overwrite_options(cdev, &coverwrite);
        return 0;
}

static struct usb_composite_driver usbg_driver = {
        .name           = "g_target",
        .dev            = &usbg_device_desc,
        .strings        = usbg_strings,
        .max_speed      = USB_SPEED_SUPER,
        .bind           = usb_target_bind,
        .unbind         = guas_unbind,
};

static int usbg_attach(struct usb_function_instance *f)
{
        return usb_composite_probe(&usbg_driver);
}

static void usbg_detach(struct usb_function_instance *f)
{
        usb_composite_unregister(&usbg_driver);
}

static int __init usb_target_gadget_init(void)
{
        struct f_tcm_opts *tcm_opts;

        fi_tcm = usb_get_function_instance("tcm");
        if (IS_ERR(fi_tcm))
                return PTR_ERR(fi_tcm);

        tcm_opts = container_of(fi_tcm, struct f_tcm_opts, func_inst);
        mutex_lock(&tcm_opts->dep_lock);
        tcm_opts->tcm_register_callback = usbg_attach;
        tcm_opts->tcm_unregister_callback = usbg_detach;
        tcm_opts->dependent = THIS_MODULE;
        tcm_opts->can_attach = true;
        tcm_opts->has_dep = true;
        mutex_unlock(&tcm_opts->dep_lock);

        fi_tcm->set_inst_name(fi_tcm, "tcm-legacy");

        return 0;
}
module_init(usb_target_gadget_init);

static void __exit usb_target_gadget_exit(void)
{
        if (!IS_ERR_OR_NULL(fi_tcm))
                usb_put_function_instance(fi_tcm);

}
module_exit(usb_target_gadget_exit);

MODULE_AUTHOR("Sebastian Andrzej Siewior <bigeasy@linutronix.de>");
MODULE_DESCRIPTION("usb-gadget fabric");
MODULE_LICENSE("GPL v2");