// SPDX-License-Identifier: GPL-2.0+
/*
 * serial.c -- USB gadget serial driver
 *
 * Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
 * Copyright (C) 2008 by David Brownell
 * Copyright (C) 2008 by Nokia Corporation
 */

#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/kstrtox.h>
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>

#include "u_serial.h"


/* Defines */

#define GS_VERSION_STR                  "v2.4"
#define GS_VERSION_NUM                  0x2400

#define GS_LONG_NAME                    "Gadget Serial"
#define GS_VERSION_NAME                 GS_LONG_NAME " " GS_VERSION_STR

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

/* Thanks to NetChip Technologies for donating this product ID.
*
* DO NOT REUSE THESE IDs with a protocol-incompatible driver!!  Ever!!
* Instead:  allocate your own, using normal USB-IF procedures.
*/
#define GS_VENDOR_ID                    0x0525  /* NetChip */
#define GS_PRODUCT_ID                   0xa4a6  /* Linux-USB Serial Gadget */
#define GS_CDC_PRODUCT_ID               0xa4a7  /* ... as CDC-ACM */
#define GS_CDC_OBEX_PRODUCT_ID          0xa4a9  /* ... as CDC-OBEX */

/* string IDs are assigned dynamically */

#define STRING_DESCRIPTION_IDX          USB_GADGET_FIRST_AVAIL_IDX

static struct usb_string strings_dev[] = {
        [USB_GADGET_MANUFACTURER_IDX].s = "",
        [USB_GADGET_PRODUCT_IDX].s = GS_VERSION_NAME,
        [USB_GADGET_SERIAL_IDX].s = "",
        [STRING_DESCRIPTION_IDX].s = NULL /* updated; f(use_acm) */,
        {  } /* 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_device_descriptor device_desc = {
        .bLength =              USB_DT_DEVICE_SIZE,
        .bDescriptorType =      USB_DT_DEVICE,
        /* .bcdUSB = DYNAMIC */
        /* .bDeviceClass = f(use_acm) */
        .bDeviceSubClass =      0,
        .bDeviceProtocol =      0,
        /* .bMaxPacketSize0 = f(hardware) */
        .idVendor =             cpu_to_le16(GS_VENDOR_ID),
        /* .idProduct = f(use_acm) */
        .bcdDevice = cpu_to_le16(GS_VERSION_NUM),
        /* .iManufacturer = DYNAMIC */
        /* .iProduct = DYNAMIC */
        .bNumConfigurations =   1,
};

static const struct usb_descriptor_header *otg_desc[2];

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

/* Module */
MODULE_DESCRIPTION(GS_VERSION_NAME);
MODULE_AUTHOR("Al Borchers");
MODULE_AUTHOR("David Brownell");
MODULE_LICENSE("GPL");

static bool use_acm = true;
module_param(use_acm, bool, 0);
MODULE_PARM_DESC(use_acm, "Use CDC ACM, default=yes");

static bool use_obex = false;
module_param(use_obex, bool, 0);
MODULE_PARM_DESC(use_obex, "Use CDC OBEX, default=no");

static unsigned n_ports = 1;
module_param(n_ports, uint, 0);
MODULE_PARM_DESC(n_ports, "number of ports to create, default=1");

static bool enable = true;

static int switch_gserial_enable(bool do_enable);

static int enable_set(const char *s, const struct kernel_param *kp)
{
        bool do_enable;
        int ret;

        if (!s) /* called for no-arg enable == default */
                return 0;

        ret = kstrtobool(s, &do_enable);
        if (ret || enable == do_enable)
                return ret;

        ret = switch_gserial_enable(do_enable);
        if (!ret)
                enable = do_enable;

        return ret;
}

static const struct kernel_param_ops enable_ops = {
        .set = enable_set,
        .get = param_get_bool,
};

module_param_cb(enable, &enable_ops, &enable, 0644);

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

static struct usb_configuration serial_config_driver = {
        /* .label = f(use_acm) */
        /* .bConfigurationValue = f(use_acm) */
        /* .iConfiguration = DYNAMIC */
        .bmAttributes   = USB_CONFIG_ATT_SELFPOWER,
};

static struct usb_function_instance *fi_serial[MAX_U_SERIAL_PORTS];
static struct usb_function *f_serial[MAX_U_SERIAL_PORTS];

static int serial_register_ports(struct usb_composite_dev *cdev,
                struct usb_configuration *c, const char *f_name)
{
        int i;
        int ret;

        ret = usb_add_config_only(cdev, c);
        if (ret)
                goto out;

        for (i = 0; i < n_ports; i++) {

                fi_serial[i] = usb_get_function_instance(f_name);
                if (IS_ERR(fi_serial[i])) {
                        ret = PTR_ERR(fi_serial[i]);
                        goto fail;
                }

                f_serial[i] = usb_get_function(fi_serial[i]);
                if (IS_ERR(f_serial[i])) {
                        ret = PTR_ERR(f_serial[i]);
                        goto err_get_func;
                }

                ret = usb_add_function(c, f_serial[i]);
                if (ret)
                        goto err_add_func;
        }

        return 0;

err_add_func:
        usb_put_function(f_serial[i]);
err_get_func:
        usb_put_function_instance(fi_serial[i]);

fail:
        i--;
        while (i >= 0) {
                usb_remove_function(c, f_serial[i]);
                usb_put_function(f_serial[i]);
                usb_put_function_instance(fi_serial[i]);
                i--;
        }
out:
        return ret;
}

static int gs_bind(struct usb_composite_dev *cdev)
{
        int                     status;

        /* Allocate string descriptor numbers ... note that string
         * contents can be overridden by the composite_dev glue.
         */

        status = usb_string_ids_tab(cdev, strings_dev);
        if (status < 0)
                goto fail;
        device_desc.iManufacturer = strings_dev[USB_GADGET_MANUFACTURER_IDX].id;
        device_desc.iProduct = strings_dev[USB_GADGET_PRODUCT_IDX].id;
        status = strings_dev[STRING_DESCRIPTION_IDX].id;
        serial_config_driver.iConfiguration = status;

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

                        usb_desc = usb_otg_descriptor_alloc(cdev->gadget);
                        if (!usb_desc) {
                                status = -ENOMEM;
                                goto fail;
                        }
                        usb_otg_descriptor_init(cdev->gadget, usb_desc);
                        otg_desc[0] = usb_desc;
                        otg_desc[1] = NULL;
                }
                serial_config_driver.descriptors = otg_desc;
                serial_config_driver.bmAttributes |= USB_CONFIG_ATT_WAKEUP;
        }

        /* register our configuration */
        if (use_acm) {
                status  = serial_register_ports(cdev, &serial_config_driver,
                                "acm");
                usb_ep_autoconfig_reset(cdev->gadget);
        } else if (use_obex)
                status = serial_register_ports(cdev, &serial_config_driver,
                                "obex");
        else {
                status = serial_register_ports(cdev, &serial_config_driver,
                                "gser");
        }
        if (status < 0)
                goto fail1;

        usb_composite_overwrite_options(cdev, &coverwrite);
        INFO(cdev, "%s\n", GS_VERSION_NAME);

        return 0;
fail1:
        kfree(otg_desc[0]);
        otg_desc[0] = NULL;
fail:
        return status;
}

static int gs_unbind(struct usb_composite_dev *cdev)
{
        int i;

        for (i = 0; i < n_ports; i++) {
                usb_put_function(f_serial[i]);
                usb_put_function_instance(fi_serial[i]);
        }

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

        return 0;
}

static struct usb_composite_driver gserial_driver = {
        .name           = "g_serial",
        .dev            = &device_desc,
        .strings        = dev_strings,
        .max_speed      = USB_SPEED_SUPER,
        .bind           = gs_bind,
        .unbind         = gs_unbind,
};

static int switch_gserial_enable(bool do_enable)
{
        if (!serial_config_driver.label)
                /* gserial_init() was not called, yet */
                return 0;

        if (do_enable)
                return usb_composite_probe(&gserial_driver);

        usb_composite_unregister(&gserial_driver);
        return 0;
}

static int __init gserial_init(void)
{
        /* We *could* export two configs; that'd be much cleaner...
         * but neither of these product IDs was defined that way.
         */
        if (use_acm) {
                serial_config_driver.label = "CDC ACM config";
                serial_config_driver.bConfigurationValue = 2;
                device_desc.bDeviceClass = USB_CLASS_COMM;
                device_desc.idProduct =
                                cpu_to_le16(GS_CDC_PRODUCT_ID);
        } else if (use_obex) {
                serial_config_driver.label = "CDC OBEX config";
                serial_config_driver.bConfigurationValue = 3;
                device_desc.bDeviceClass = USB_CLASS_COMM;
                device_desc.idProduct =
                        cpu_to_le16(GS_CDC_OBEX_PRODUCT_ID);
        } else {
                serial_config_driver.label = "Generic Serial config";
                serial_config_driver.bConfigurationValue = 1;
                device_desc.bDeviceClass = USB_CLASS_VENDOR_SPEC;
                device_desc.idProduct =
                                cpu_to_le16(GS_PRODUCT_ID);
        }
        strings_dev[STRING_DESCRIPTION_IDX].s = serial_config_driver.label;

        if (!enable)
                return 0;

        return usb_composite_probe(&gserial_driver);
}
module_init(gserial_init);

static void __exit gserial_cleanup(void)
{
        if (enable)
                usb_composite_unregister(&gserial_driver);
}
module_exit(gserial_cleanup);