// SPDX-License-Identifier: GPL-2.0+
/*
 * f_obex.c -- USB CDC OBEX function driver
 *
 * Copyright (C) 2008 Nokia Corporation
 * Contact: Felipe Balbi <felipe.balbi@nokia.com>
 *
 * Based on f_acm.c by Al Borchers and David Brownell.
 */

/* #define VERBOSE_DEBUG */

#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/module.h>

#include "u_serial.h"


/*
 * This CDC OBEX function support just packages a TTY-ish byte stream.
 * A user mode server will put it into "raw" mode and handle all the
 * relevant protocol details ... this is just a kernel passthrough.
 * When possible, we prevent gadget enumeration until that server is
 * ready to handle the commands.
 */

struct f_obex {
        struct gserial                  port;
        u8                              ctrl_id;
        u8                              data_id;
        u8                              cur_alt;
        u8                              port_num;
};

static inline struct f_obex *func_to_obex(struct usb_function *f)
{
        return container_of(f, struct f_obex, port.func);
}

static inline struct f_obex *port_to_obex(struct gserial *p)
{
        return container_of(p, struct f_obex, port);
}

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

#define OBEX_CTRL_IDX   0
#define OBEX_DATA_IDX   1

static struct usb_string obex_string_defs[] = {
        [OBEX_CTRL_IDX].s       = "CDC Object Exchange (OBEX)",
        [OBEX_DATA_IDX].s       = "CDC OBEX Data",
        {  },   /* end of list */
};

static struct usb_gadget_strings obex_string_table = {
        .language               = 0x0409,       /* en-US */
        .strings                = obex_string_defs,
};

static struct usb_gadget_strings *obex_strings[] = {
        &obex_string_table,
        NULL,
};

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

static struct usb_interface_descriptor obex_control_intf = {
        .bLength                = sizeof(obex_control_intf),
        .bDescriptorType        = USB_DT_INTERFACE,
        .bInterfaceNumber       = 0,

        .bAlternateSetting      = 0,
        .bNumEndpoints          = 0,
        .bInterfaceClass        = USB_CLASS_COMM,
        .bInterfaceSubClass     = USB_CDC_SUBCLASS_OBEX,
};

static struct usb_interface_descriptor obex_data_nop_intf = {
        .bLength                = sizeof(obex_data_nop_intf),
        .bDescriptorType        = USB_DT_INTERFACE,
        .bInterfaceNumber       = 1,

        .bAlternateSetting      = 0,
        .bNumEndpoints          = 0,
        .bInterfaceClass        = USB_CLASS_CDC_DATA,
};

static struct usb_interface_descriptor obex_data_intf = {
        .bLength                = sizeof(obex_data_intf),
        .bDescriptorType        = USB_DT_INTERFACE,
        .bInterfaceNumber       = 2,

        .bAlternateSetting      = 1,
        .bNumEndpoints          = 2,
        .bInterfaceClass        = USB_CLASS_CDC_DATA,
};

static struct usb_cdc_header_desc obex_cdc_header_desc = {
        .bLength                = sizeof(obex_cdc_header_desc),
        .bDescriptorType        = USB_DT_CS_INTERFACE,
        .bDescriptorSubType     = USB_CDC_HEADER_TYPE,
        .bcdCDC                 = cpu_to_le16(0x0120),
};

static struct usb_cdc_union_desc obex_cdc_union_desc = {
        .bLength                = sizeof(obex_cdc_union_desc),
        .bDescriptorType        = USB_DT_CS_INTERFACE,
        .bDescriptorSubType     = USB_CDC_UNION_TYPE,
        .bMasterInterface0      = 1,
        .bSlaveInterface0       = 2,
};

static struct usb_cdc_obex_desc obex_desc = {
        .bLength                = sizeof(obex_desc),
        .bDescriptorType        = USB_DT_CS_INTERFACE,
        .bDescriptorSubType     = USB_CDC_OBEX_TYPE,
        .bcdVersion             = cpu_to_le16(0x0100),
};

/* High-Speed Support */

static struct usb_endpoint_descriptor obex_hs_ep_out_desc = {
        .bLength                = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType        = USB_DT_ENDPOINT,

        .bEndpointAddress       = USB_DIR_OUT,
        .bmAttributes           = USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize         = cpu_to_le16(512),
};

static struct usb_endpoint_descriptor obex_hs_ep_in_desc = {
        .bLength                = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType        = USB_DT_ENDPOINT,

        .bEndpointAddress       = USB_DIR_IN,
        .bmAttributes           = USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize         = cpu_to_le16(512),
};

static struct usb_descriptor_header *hs_function[] = {
        (struct usb_descriptor_header *) &obex_control_intf,
        (struct usb_descriptor_header *) &obex_cdc_header_desc,
        (struct usb_descriptor_header *) &obex_desc,
        (struct usb_descriptor_header *) &obex_cdc_union_desc,

        (struct usb_descriptor_header *) &obex_data_nop_intf,
        (struct usb_descriptor_header *) &obex_data_intf,
        (struct usb_descriptor_header *) &obex_hs_ep_in_desc,
        (struct usb_descriptor_header *) &obex_hs_ep_out_desc,
        NULL,
};

/* Full-Speed Support */

static struct usb_endpoint_descriptor obex_fs_ep_in_desc = {
        .bLength                = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType        = USB_DT_ENDPOINT,

        .bEndpointAddress       = USB_DIR_IN,
        .bmAttributes           = USB_ENDPOINT_XFER_BULK,
};

static struct usb_endpoint_descriptor obex_fs_ep_out_desc = {
        .bLength                = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType        = USB_DT_ENDPOINT,

        .bEndpointAddress       = USB_DIR_OUT,
        .bmAttributes           = USB_ENDPOINT_XFER_BULK,
};

static struct usb_descriptor_header *fs_function[] = {
        (struct usb_descriptor_header *) &obex_control_intf,
        (struct usb_descriptor_header *) &obex_cdc_header_desc,
        (struct usb_descriptor_header *) &obex_desc,
        (struct usb_descriptor_header *) &obex_cdc_union_desc,

        (struct usb_descriptor_header *) &obex_data_nop_intf,
        (struct usb_descriptor_header *) &obex_data_intf,
        (struct usb_descriptor_header *) &obex_fs_ep_in_desc,
        (struct usb_descriptor_header *) &obex_fs_ep_out_desc,
        NULL,
};

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

static int obex_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
{
        struct f_obex           *obex = func_to_obex(f);
        struct usb_composite_dev *cdev = f->config->cdev;

        if (intf == obex->ctrl_id) {
                if (alt != 0)
                        goto fail;
                /* NOP */
                dev_dbg(&cdev->gadget->dev,
                        "reset obex ttyGS%d control\n", obex->port_num);

        } else if (intf == obex->data_id) {
                if (alt > 1)
                        goto fail;

                if (obex->port.in->enabled) {
                        dev_dbg(&cdev->gadget->dev,
                                "reset obex ttyGS%d\n", obex->port_num);
                        gserial_disconnect(&obex->port);
                }

                if (!obex->port.in->desc || !obex->port.out->desc) {
                        dev_dbg(&cdev->gadget->dev,
                                "init obex ttyGS%d\n", obex->port_num);
                        if (config_ep_by_speed(cdev->gadget, f,
                                               obex->port.in) ||
                            config_ep_by_speed(cdev->gadget, f,
                                               obex->port.out)) {
                                obex->port.out->desc = NULL;
                                obex->port.in->desc = NULL;
                                goto fail;
                        }
                }

                if (alt == 1) {
                        dev_dbg(&cdev->gadget->dev,
                                "activate obex ttyGS%d\n", obex->port_num);
                        gserial_connect(&obex->port, obex->port_num);
                }

        } else
                goto fail;

        obex->cur_alt = alt;

        return 0;

fail:
        return -EINVAL;
}

static int obex_get_alt(struct usb_function *f, unsigned intf)
{
        struct f_obex           *obex = func_to_obex(f);

        return obex->cur_alt;
}

static void obex_disable(struct usb_function *f)
{
        struct f_obex   *obex = func_to_obex(f);
        struct usb_composite_dev *cdev = f->config->cdev;

        dev_dbg(&cdev->gadget->dev, "obex ttyGS%d disable\n", obex->port_num);
        gserial_disconnect(&obex->port);
}

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

static void obex_connect(struct gserial *g)
{
        struct f_obex           *obex = port_to_obex(g);
        struct usb_composite_dev *cdev = g->func.config->cdev;
        int                     status;

        status = usb_function_activate(&g->func);
        if (status)
                dev_dbg(&cdev->gadget->dev,
                        "obex ttyGS%d function activate --> %d\n",
                        obex->port_num, status);
}

static void obex_disconnect(struct gserial *g)
{
        struct f_obex           *obex = port_to_obex(g);
        struct usb_composite_dev *cdev = g->func.config->cdev;
        int                     status;

        status = usb_function_deactivate(&g->func);
        if (status)
                dev_dbg(&cdev->gadget->dev,
                        "obex ttyGS%d function deactivate --> %d\n",
                        obex->port_num, status);
}

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

/* Some controllers can't support CDC OBEX ... */
static inline bool can_support_obex(struct usb_configuration *c)
{
        /* Since the first interface is a NOP, we can ignore the
         * issue of multi-interface support on most controllers.
         *
         * Altsettings are mandatory, however...
         */
        if (!gadget_is_altset_supported(c->cdev->gadget))
                return false;

        /* everything else is *probably* fine ... */
        return true;
}

static int obex_bind(struct usb_configuration *c, struct usb_function *f)
{
        struct usb_composite_dev *cdev = c->cdev;
        struct f_obex           *obex = func_to_obex(f);
        struct usb_string       *us;
        int                     status;
        struct usb_ep           *ep;

        if (!can_support_obex(c))
                return -EINVAL;

        us = usb_gstrings_attach(cdev, obex_strings,
                                 ARRAY_SIZE(obex_string_defs));
        if (IS_ERR(us))
                return PTR_ERR(us);
        obex_control_intf.iInterface = us[OBEX_CTRL_IDX].id;
        obex_data_nop_intf.iInterface = us[OBEX_DATA_IDX].id;
        obex_data_intf.iInterface = us[OBEX_DATA_IDX].id;

        /* allocate instance-specific interface IDs, and patch descriptors */

        status = usb_interface_id(c, f);
        if (status < 0)
                goto fail;
        obex->ctrl_id = status;

        obex_control_intf.bInterfaceNumber = status;
        obex_cdc_union_desc.bMasterInterface0 = status;

        status = usb_interface_id(c, f);
        if (status < 0)
                goto fail;
        obex->data_id = status;

        obex_data_nop_intf.bInterfaceNumber = status;
        obex_data_intf.bInterfaceNumber = status;
        obex_cdc_union_desc.bSlaveInterface0 = status;

        /* allocate instance-specific endpoints */

        status = -ENODEV;
        ep = usb_ep_autoconfig(cdev->gadget, &obex_fs_ep_in_desc);
        if (!ep)
                goto fail;
        obex->port.in = ep;

        ep = usb_ep_autoconfig(cdev->gadget, &obex_fs_ep_out_desc);
        if (!ep)
                goto fail;
        obex->port.out = ep;

        /* support all relevant hardware speeds... we expect that when
         * hardware is dual speed, all bulk-capable endpoints work at
         * both speeds
         */

        obex_hs_ep_in_desc.bEndpointAddress =
                obex_fs_ep_in_desc.bEndpointAddress;
        obex_hs_ep_out_desc.bEndpointAddress =
                obex_fs_ep_out_desc.bEndpointAddress;

        status = usb_assign_descriptors(f, fs_function, hs_function, NULL,
                                        NULL);
        if (status)
                goto fail;

        dev_dbg(&cdev->gadget->dev, "obex ttyGS%d: IN/%s OUT/%s\n",
                obex->port_num,
                obex->port.in->name, obex->port.out->name);

        return 0;

fail:
        ERROR(cdev, "%s/%p: can't bind, err %d\n", f->name, f, status);

        return status;
}

static inline struct f_serial_opts *to_f_serial_opts(struct config_item *item)
{
        return container_of(to_config_group(item), struct f_serial_opts,
                            func_inst.group);
}

static void obex_attr_release(struct config_item *item)
{
        struct f_serial_opts *opts = to_f_serial_opts(item);

        usb_put_function_instance(&opts->func_inst);
}

static const struct configfs_item_operations obex_item_ops = {
        .release        = obex_attr_release,
};

static ssize_t f_obex_port_num_show(struct config_item *item, char *page)
{
        return sprintf(page, "%u\n", to_f_serial_opts(item)->port_num);
}

CONFIGFS_ATTR_RO(f_obex_, port_num);

static struct configfs_attribute *acm_attrs[] = {
        &f_obex_attr_port_num,
        NULL,
};

static const struct config_item_type obex_func_type = {
        .ct_item_ops    = &obex_item_ops,
        .ct_attrs       = acm_attrs,
        .ct_owner       = THIS_MODULE,
};

static void obex_free_inst(struct usb_function_instance *f)
{
        struct f_serial_opts *opts;

        opts = container_of(f, struct f_serial_opts, func_inst);
        gserial_free_line(opts->port_num);
        kfree(opts);
}

static struct usb_function_instance *obex_alloc_inst(void)
{
        struct f_serial_opts *opts;
        int ret;

        opts = kzalloc_obj(*opts);
        if (!opts)
                return ERR_PTR(-ENOMEM);

        opts->func_inst.free_func_inst = obex_free_inst;
        ret = gserial_alloc_line_no_console(&opts->port_num);
        if (ret) {
                kfree(opts);
                return ERR_PTR(ret);
        }
        config_group_init_type_name(&opts->func_inst.group, "",
                                    &obex_func_type);

        return &opts->func_inst;
}

static void obex_free(struct usb_function *f)
{
        struct f_obex *obex;

        obex = func_to_obex(f);
        kfree(obex);
}

static void obex_unbind(struct usb_configuration *c, struct usb_function *f)
{
        usb_free_all_descriptors(f);
}

static struct usb_function *obex_alloc(struct usb_function_instance *fi)
{
        struct f_obex   *obex;
        struct f_serial_opts *opts;

        /* allocate and initialize one new instance */
        obex = kzalloc_obj(*obex);
        if (!obex)
                return ERR_PTR(-ENOMEM);

        opts = container_of(fi, struct f_serial_opts, func_inst);

        obex->port_num = opts->port_num;

        obex->port.connect = obex_connect;
        obex->port.disconnect = obex_disconnect;

        obex->port.func.name = "obex";
        /* descriptors are per-instance copies */
        obex->port.func.bind = obex_bind;
        obex->port.func.unbind = obex_unbind;
        obex->port.func.set_alt = obex_set_alt;
        obex->port.func.get_alt = obex_get_alt;
        obex->port.func.disable = obex_disable;
        obex->port.func.free_func = obex_free;
        obex->port.func.bind_deactivated = true;

        return &obex->port.func;
}

DECLARE_USB_FUNCTION_INIT(obex, obex_alloc_inst, obex_alloc);
MODULE_AUTHOR("Felipe Balbi");
MODULE_DESCRIPTION("USB CDC OBEX function driver");
MODULE_LICENSE("GPL");