f_serial.c

Go to the documentation of this file.

/*
 * f_serial.c - generic USB serial function driver
 *
 * Copyright (C) 2003 Al Borchers ([email protected])
 * Copyright (C) 2008 by David Brownell
 * Copyright (C) 2008 by Nokia Corporation
 *
 * This software is distributed under the terms of the GNU General
 * Public License ("GPL") as published by the Free Software Foundation,
 * either version 2 of that License or (at your option) any later version.
 */

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

#include "u_serial.h"
#include "gadget_chips.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 __initdata = {
    .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 __initdata = {
    .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 __initdata = {
    .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[] __initdata = {
    (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 __initdata = {
    .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 __initdata = {
    .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[] __initdata = {
    (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 __initdata = {
    .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 __initdata = {
    .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 __initdata = {
    .bLength =              sizeof gser_ss_bulk_comp_desc,
    .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
};

static struct usb_descriptor_header *gser_ss_function[] __initdata = {
    (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->driver_data) {
        DBG(cdev, "reset generic ttyGS%d\n", gser->port_num);
        gserial_disconnect(&gser->port);
    }
    if (!gser->port.in->desc || !gser->port.out->desc) {
        DBG(cdev, "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;

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

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

/* serial function driver setup/binding */

static int __init
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;

    /* 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->driver_data = cdev; /* claim */

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

    /* copy descriptors, and track endpoint copies */
    f->descriptors = usb_copy_descriptors(gser_fs_function);

    /* support all relevant hardware speeds... we expect that when
     * hardware is dual speed, all bulk-capable endpoints work at
     * both speeds
     */
    if (gadget_is_dualspeed(c->cdev->gadget)) {
        gser_hs_in_desc.bEndpointAddress =
                gser_fs_in_desc.bEndpointAddress;
        gser_hs_out_desc.bEndpointAddress =
                gser_fs_out_desc.bEndpointAddress;

        /* copy descriptors, and track endpoint copies */
        f->hs_descriptors = usb_copy_descriptors(gser_hs_function);
    }
    if (gadget_is_superspeed(c->cdev->gadget)) {
        gser_ss_in_desc.bEndpointAddress =
            gser_fs_in_desc.bEndpointAddress;
        gser_ss_out_desc.bEndpointAddress =
            gser_fs_out_desc.bEndpointAddress;

        /* copy descriptors, and track endpoint copies */
        f->ss_descriptors = usb_copy_descriptors(gser_ss_function);
        if (!f->ss_descriptors)
            goto fail;
    }

    DBG(cdev, "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:
    /* we might as well release our claims on endpoints */
    if (gser->port.out)
        gser->port.out->driver_data = NULL;
    if (gser->port.in)
        gser->port.in->driver_data = NULL;

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

    return status;
}

static void
gser_unbind(struct usb_configuration *c, struct usb_function *f)
{
    if (gadget_is_dualspeed(c->cdev->gadget))
        usb_free_descriptors(f->hs_descriptors);
    if (gadget_is_superspeed(c->cdev->gadget))
        usb_free_descriptors(f->ss_descriptors);
    usb_free_descriptors(f->descriptors);
    kfree(func_to_gser(f));
}

int __init gser_bind_config(struct usb_configuration *c, u8 port_num)
{
    struct f_gser   *gser;
    int     status;

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

    gser->port_num = 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;

    status = usb_add_function(c, &gser->port.func);
    if (status)
        kfree(gser);
    return status;
}