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

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

#include "u_serial.h"


/*
 * This function packages a simple "generic serial" port with no real
 * control mechanisms, just raw data transfer over two bulk endpoints.
 *
 * Because it's not standardized, this isn't as interoperable as the
 * CDC ACM driver.  However, for many purposes it's just as functional
 * if you can arrange appropriate host side drivers.
 */

struct f_gser {
        struct gserial                  port;
        u8                              data_id;
        u8                              port_num;
};

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

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

/* interface descriptor: */

static struct usb_interface_descriptor gser_interface_desc = {
        .bLength =              USB_DT_INTERFACE_SIZE,
        .bDescriptorType =      USB_DT_INTERFACE,
        /* .bInterfaceNumber = DYNAMIC */
        .bNumEndpoints =        2,
        .bInterfaceClass =      USB_CLASS_VENDOR_SPEC,
        .bInterfaceSubClass =   0,
        .bInterfaceProtocol =   0,
        /* .iInterface = DYNAMIC */
};

/* full speed support: */

static struct usb_endpoint_descriptor gser_fs_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 gser_fs_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 *gser_fs_function[] = {
        (struct usb_descriptor_header *) &gser_interface_desc,
        (struct usb_descriptor_header *) &gser_fs_in_desc,
        (struct usb_descriptor_header *) &gser_fs_out_desc,
        NULL,
};

/* high speed support: */

static struct usb_endpoint_descriptor gser_hs_in_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(512),
};

static struct usb_endpoint_descriptor gser_hs_out_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(512),
};

static struct usb_descriptor_header *gser_hs_function[] = {
        (struct usb_descriptor_header *) &gser_interface_desc,
        (struct usb_descriptor_header *) &gser_hs_in_desc,
        (struct usb_descriptor_header *) &gser_hs_out_desc,
        NULL,
};

static struct usb_endpoint_descriptor gser_ss_in_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(1024),
};

static struct usb_endpoint_descriptor gser_ss_out_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(1024),
};

static struct usb_ss_ep_comp_descriptor gser_ss_bulk_comp_desc = {
        .bLength =              sizeof gser_ss_bulk_comp_desc,
        .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
};

static struct usb_descriptor_header *gser_ss_function[] = {
        (struct usb_descriptor_header *) &gser_interface_desc,
        (struct usb_descriptor_header *) &gser_ss_in_desc,
        (struct usb_descriptor_header *) &gser_ss_bulk_comp_desc,
        (struct usb_descriptor_header *) &gser_ss_out_desc,
        (struct usb_descriptor_header *) &gser_ss_bulk_comp_desc,
        NULL,
};

/* string descriptors: */

static struct usb_string gser_string_defs[] = {
        [0].s = "Generic Serial",
        {  } /* end of list */
};

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

static struct usb_gadget_strings *gser_strings[] = {
        &gser_string_table,
        NULL,
};

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

static int gser_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
{
        struct f_gser           *gser = func_to_gser(f);
        struct usb_composite_dev *cdev = f->config->cdev;

        /* we know alt == 0, so this is an activation or a reset */

        if (gser->port.in->enabled) {
                dev_dbg(&cdev->gadget->dev,
                        "reset generic ttyGS%d\n", gser->port_num);
                gserial_disconnect(&gser->port);
        }
        if (!gser->port.in->desc || !gser->port.out->desc) {
                dev_dbg(&cdev->gadget->dev,
                        "activate generic ttyGS%d\n", gser->port_num);
                if (config_ep_by_speed(cdev->gadget, f, gser->port.in) ||
                    config_ep_by_speed(cdev->gadget, f, gser->port.out)) {
                        gser->port.in->desc = NULL;
                        gser->port.out->desc = NULL;
                        return -EINVAL;
                }
        }
        gserial_connect(&gser->port, gser->port_num);
        return 0;
}

static void gser_disable(struct usb_function *f)
{
        struct f_gser   *gser = func_to_gser(f);
        struct usb_composite_dev *cdev = f->config->cdev;

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

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

/* serial function driver setup/binding */

static int gser_bind(struct usb_configuration *c, struct usb_function *f)
{
        struct usb_composite_dev *cdev = c->cdev;
        struct f_gser           *gser = func_to_gser(f);
        int                     status;
        struct usb_ep           *ep;

        /* REVISIT might want instance-specific strings to help
         * distinguish instances ...
         */

        /* maybe allocate device-global string ID */
        if (gser_string_defs[0].id == 0) {
                status = usb_string_id(c->cdev);
                if (status < 0)
                        return status;
                gser_string_defs[0].id = status;
        }

        /* allocate instance-specific interface IDs */
        status = usb_interface_id(c, f);
        if (status < 0)
                goto fail;
        gser->data_id = status;
        gser_interface_desc.bInterfaceNumber = status;

        status = -ENODEV;

        /* allocate instance-specific endpoints */
        ep = usb_ep_autoconfig(cdev->gadget, &gser_fs_in_desc);
        if (!ep)
                goto fail;
        gser->port.in = ep;

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

        /* support all relevant hardware speeds... we expect that when
         * hardware is dual speed, all bulk-capable endpoints work at
         * both speeds
         */
        gser_hs_in_desc.bEndpointAddress = gser_fs_in_desc.bEndpointAddress;
        gser_hs_out_desc.bEndpointAddress = gser_fs_out_desc.bEndpointAddress;

        gser_ss_in_desc.bEndpointAddress = gser_fs_in_desc.bEndpointAddress;
        gser_ss_out_desc.bEndpointAddress = gser_fs_out_desc.bEndpointAddress;

        status = usb_assign_descriptors(f, gser_fs_function, gser_hs_function,
                        gser_ss_function, NULL);
        if (status)
                goto fail;
        dev_dbg(&cdev->gadget->dev, "generic ttyGS%d: %s speed IN/%s OUT/%s\n",
                gser->port_num,
                gadget_is_superspeed(c->cdev->gadget) ? "super" :
                gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
                gser->port.in->name, gser->port.out->name);
        return 0;

fail:
        ERROR(cdev, "%s: can't bind, err %d\n", f->name, 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 serial_attr_release(struct config_item *item)
{
        struct f_serial_opts *opts = to_f_serial_opts(item);

        usb_put_function_instance(&opts->func_inst);
}

static struct configfs_item_operations serial_item_ops = {
        .release        = serial_attr_release,
};

static ssize_t f_serial_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_serial_, port_num);

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

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

static void gser_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 *gser_alloc_inst(void)
{
        struct f_serial_opts *opts;
        int ret;

        opts = kzalloc(sizeof(*opts), GFP_KERNEL);
        if (!opts)
                return ERR_PTR(-ENOMEM);

        opts->func_inst.free_func_inst = gser_free_inst;
        ret = gserial_alloc_line(&opts->port_num);
        if (ret) {
                kfree(opts);
                return ERR_PTR(ret);
        }
        config_group_init_type_name(&opts->func_inst.group, "",
                                    &serial_func_type);

        return &opts->func_inst;
}

static void gser_free(struct usb_function *f)
{
        struct f_gser *serial;

        serial = func_to_gser(f);
        kfree(serial);
}

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

static struct usb_function *gser_alloc(struct usb_function_instance *fi)
{
        struct f_gser   *gser;
        struct f_serial_opts *opts;

        /* allocate and initialize one new instance */
        gser = kzalloc(sizeof(*gser), GFP_KERNEL);
        if (!gser)
                return ERR_PTR(-ENOMEM);

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

        gser->port_num = opts->port_num;

        gser->port.func.name = "gser";
        gser->port.func.strings = gser_strings;
        gser->port.func.bind = gser_bind;
        gser->port.func.unbind = gser_unbind;
        gser->port.func.set_alt = gser_set_alt;
        gser->port.func.disable = gser_disable;
        gser->port.func.free_func = gser_free;

        return &gser->port.func;
}

DECLARE_USB_FUNCTION_INIT(gser, gser_alloc_inst, gser_alloc);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Al Borchers");
MODULE_AUTHOR("David Brownell");