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* composite.h -- framework for usb gadgets which are composite devices
* Copyright (C) 2006-2008 David Brownell
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
* This framework is an optional layer on top of the USB Gadget interface,
* making it easier to build (a) Composite devices, supporting multiple
* functions within any single configuration, and (b) Multi-configuration
* devices, also supporting multiple functions but without necessarily
* having more than one function per configuration.
* Example: a device with a single configuration supporting both network
* link and mass storage functions is a composite device. Those functions
* might alternatively be packaged in individual configurations, but in
* the composite model the host can use both functions at the same time.
#include <common.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <usb/lin_gadget_compat.h>
struct usb_configuration;
* struct usb_function - describes one function of a configuration
* @name: For diagnostics, identifies the function.
* @strings: tables of strings, keyed by identifiers assigned during bind()
* and by language IDs provided in control requests
* @descriptors: Table of full (or low) speed descriptors, using interface and
* string identifiers assigned during @bind(). If this pointer is null,
* the function will not be available at full speed (or at low speed).
* @hs_descriptors: Table of high speed descriptors, using interface and
* string identifiers assigned during @bind(). If this pointer is null,
* the function will not be available at high speed.
* @config: assigned when @usb_add_function() is called; this is the
* configuration with which this function is associated.
* @bind: Before the gadget can register, all of its functions bind() to the
* available resources including string and interface identifiers used
* in interface or class descriptors; endpoints; I/O buffers; and so on.
* @unbind: Reverses @bind; called as a side effect of unregistering the
* driver which added this function.
* @set_alt: (REQUIRED) Reconfigures altsettings; function drivers may
* initialize usb_ep.driver data at this time (when it is used).
* Note that setting an interface to its current altsetting resets
* interface state, and that all interfaces have a disabled state.
* @get_alt: Returns the active altsetting. If this is not provided,
* then only altsetting zero is supported.
* @disable: (REQUIRED) Indicates the function should be disabled. Reasons
* include host resetting or reconfiguring the gadget, and disconnection.
* @setup: Used for interface-specific control requests.
* @suspend: Notifies functions when the host stops sending USB traffic.
* @resume: Notifies functions when the host restarts USB traffic.
* A single USB function uses one or more interfaces, and should in most
* cases support operation at both full and high speeds. Each function is
* associated by @usb_add_function() with a one configuration; that function
* causes @bind() to be called so resources can be allocated as part of
* setting up a gadget driver. Those resources include endpoints, which
* should be allocated using @usb_ep_autoconfig().
* To support dual speed operation, a function driver provides descriptors
* for both high and full speed operation. Except in rare cases that don't
* involve bulk endpoints, each speed needs different endpoint descriptors.
* Function drivers choose their own strategies for managing instance data.
* The simplest strategy just declares it "static', which means the function
* can only be activated once. If the function needs to be exposed in more
* than one configuration at a given speed, it needs to support multiple
* usb_function structures (one for each configuration).
* A more complex strategy might encapsulate a @usb_function structure inside
* a driver-specific instance structure to allows multiple activations. An
* example of multiple activations might be a CDC ACM function that supports
* two or more distinct instances within the same configuration, providing
* several independent logical data links to a USB host.
struct usb_function {
const char *name;
struct usb_gadget_strings **strings;
struct usb_descriptor_header **descriptors;
struct usb_descriptor_header **hs_descriptors;
struct usb_configuration *config;
/* REVISIT: bind() functions can be marked __init, which
* makes trouble for section mismatch analysis. See if
* we can't restructure things to avoid mismatching.
* Related: unbind() may kfree() but bind() won't...
/* configuration management: bind/unbind */
int (*bind)(struct usb_configuration *,
struct usb_function *);
void (*unbind)(struct usb_configuration *,
struct usb_function *);
/* runtime state management */
int (*set_alt)(struct usb_function *,
unsigned interface, unsigned alt);
int (*get_alt)(struct usb_function *,
unsigned interface);
void (*disable)(struct usb_function *);
int (*setup)(struct usb_function *,
const struct usb_ctrlrequest *);
void (*suspend)(struct usb_function *);
void (*resume)(struct usb_function *);
/* private: */
/* internals */
struct list_head list;
DECLARE_BITMAP(endpoints, 32);
int usb_add_function(struct usb_configuration *, struct usb_function *);
int usb_function_deactivate(struct usb_function *);
int usb_function_activate(struct usb_function *);
int usb_interface_id(struct usb_configuration *, struct usb_function *);
* ep_choose - select descriptor endpoint at current device speed
* @g: gadget, connected and running at some speed
* @hs: descriptor to use for high speed operation
* @fs: descriptor to use for full or low speed operation
static inline struct usb_endpoint_descriptor *
ep_choose(struct usb_gadget *g, struct usb_endpoint_descriptor *hs,
struct usb_endpoint_descriptor *fs)
if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH)
return hs;
return fs;
#define MAX_CONFIG_INTERFACES 16 /* arbitrary; max 255 */
* struct usb_configuration - represents one gadget configuration
* @label: For diagnostics, describes the configuration.
* @strings: Tables of strings, keyed by identifiers assigned during @bind()
* and by language IDs provided in control requests.
* @descriptors: Table of descriptors preceding all function descriptors.
* Examples include OTG and vendor-specific descriptors.
* @bind: Called from @usb_add_config() to allocate resources unique to this
* configuration and to call @usb_add_function() for each function used.
* @unbind: Reverses @bind; called as a side effect of unregistering the
* driver which added this configuration.
* @setup: Used to delegate control requests that aren't handled by standard
* device infrastructure or directed at a specific interface.
* @bConfigurationValue: Copied into configuration descriptor.
* @iConfiguration: Copied into configuration descriptor.
* @bmAttributes: Copied into configuration descriptor.
* @bMaxPower: Copied into configuration descriptor.
* @cdev: assigned by @usb_add_config() before calling @bind(); this is
* the device associated with this configuration.
* Configurations are building blocks for gadget drivers structured around
* function drivers. Simple USB gadgets require only one function and one
* configuration, and handle dual-speed hardware by always providing the same
* functionality. Slightly more complex gadgets may have more than one
* single-function configuration at a given speed; or have configurations
* that only work at one speed.
* Composite devices are, by definition, ones with configurations which
* include more than one function.
* The lifecycle of a usb_configuration includes allocation, initialization
* of the fields described above, and calling @usb_add_config() to set up
* internal data and bind it to a specific device. The configuration's
* @bind() method is then used to initialize all the functions and then
* call @usb_add_function() for them.
* Those functions would normally be independant of each other, but that's
* not mandatory. CDC WMC devices are an example where functions often
* depend on other functions, with some functions subsidiary to others.
* Such interdependency may be managed in any way, so long as all of the
* descriptors complete by the time the composite driver returns from
* its bind() routine.
struct usb_configuration {
const char *label;
struct usb_gadget_strings **strings;
const struct usb_descriptor_header **descriptors;
/* REVISIT: bind() functions can be marked __init, which
* makes trouble for section mismatch analysis. See if
* we can't restructure things to avoid mismatching...
/* configuration management: bind/unbind */
int (*bind)(struct usb_configuration *);
void (*unbind)(struct usb_configuration *);
int (*setup)(struct usb_configuration *,
const struct usb_ctrlrequest *);
/* fields in the config descriptor */
u8 bConfigurationValue;
u8 iConfiguration;
u8 bmAttributes;
u8 bMaxPower;
struct usb_composite_dev *cdev;
/* private: */
/* internals */
struct list_head list;
struct list_head functions;
u8 next_interface_id;
unsigned highspeed:1;
unsigned fullspeed:1;
struct usb_function *interface[MAX_CONFIG_INTERFACES];
int usb_add_config(struct usb_composite_dev *,
struct usb_configuration *);
* struct usb_composite_driver - groups configurations into a gadget
* @name: For diagnostics, identifies the driver.
* @dev: Template descriptor for the device, including default device
* identifiers.
* @strings: tables of strings, keyed by identifiers assigned during bind()
* and language IDs provided in control requests
* @bind: (REQUIRED) Used to allocate resources that are shared across the
* whole device, such as string IDs, and add its configurations using
* @usb_add_config(). This may fail by returning a negative errno
* value; it should return zero on successful initialization.
* @unbind: Reverses @bind(); called as a side effect of unregistering
* this driver.
* @disconnect: optional driver disconnect method
* @suspend: Notifies when the host stops sending USB traffic,
* after function notifications
* @resume: Notifies configuration when the host restarts USB traffic,
* before function notifications
* Devices default to reporting self powered operation. Devices which rely
* on bus powered operation should report this in their @bind() method.
* Before returning from @bind, various fields in the template descriptor
* may be overridden. These include the idVendor/idProduct/bcdDevice values
* normally to bind the appropriate host side driver, and the three strings
* (iManufacturer, iProduct, iSerialNumber) normally used to provide user
* meaningful device identifiers. (The strings will not be defined unless
* they are defined in @dev and @strings.) The correct ep0 maxpacket size
* is also reported, as defined by the underlying controller driver.
struct usb_composite_driver {
const char *name;
const struct usb_device_descriptor *dev;
struct usb_gadget_strings **strings;
/* REVISIT: bind() functions can be marked __init, which
* makes trouble for section mismatch analysis. See if
* we can't restructure things to avoid mismatching...
int (*bind)(struct usb_composite_dev *);
int (*unbind)(struct usb_composite_dev *);
void (*disconnect)(struct usb_composite_dev *);
/* global suspend hooks */
void (*suspend)(struct usb_composite_dev *);
void (*resume)(struct usb_composite_dev *);
extern int usb_composite_register(struct usb_composite_driver *);
extern void usb_composite_unregister(struct usb_composite_driver *);
* struct usb_composite_device - represents one composite usb gadget
* @gadget: read-only, abstracts the gadget's usb peripheral controller
* @req: used for control responses; buffer is pre-allocated
* @bufsiz: size of buffer pre-allocated in @req
* @config: the currently active configuration
* One of these devices is allocated and initialized before the
* associated device driver's bind() is called.
* OPEN ISSUE: it appears that some WUSB devices will need to be
* built by combining a normal (wired) gadget with a wireless one.
* This revision of the gadget framework should probably try to make
* sure doing that won't hurt too much.
* One notion for how to handle Wireless USB devices involves:
* (a) a second gadget here, discovery mechanism TBD, but likely
* needing separate "register/unregister WUSB gadget" calls;
* (b) updates to usb_gadget to include flags "is it wireless",
* "is it wired", plus (presumably in a wrapper structure)
* bandgroup and PHY info;
* (c) presumably a wireless_ep wrapping a usb_ep, and reporting
* wireless-specific parameters like maxburst and maxsequence;
* (d) configurations that are specific to wireless links;
* (e) function drivers that understand wireless configs and will
* support wireless for (additional) function instances;
* (f) a function to support association setup (like CBAF), not
* necessarily requiring a wireless adapter;
* (g) composite device setup that can create one or more wireless
* configs, including appropriate association setup support;
* (h) more, TBD.
struct usb_composite_dev {
struct usb_gadget *gadget;
struct usb_request *req;
unsigned bufsiz;
struct usb_configuration *config;
/* private: */
/* internals */
unsigned int suspended:1;
struct usb_device_descriptor desc;
struct list_head configs;
struct usb_composite_driver *driver;
u8 next_string_id;
/* the gadget driver won't enable the data pullup
* while the deactivation count is nonzero.
unsigned deactivations;
extern int usb_string_id(struct usb_composite_dev *c);
extern int usb_string_ids_tab(struct usb_composite_dev *c,
struct usb_string *str);
extern int usb_string_ids_n(struct usb_composite_dev *c, unsigned n);
#endif /* __LINUX_USB_COMPOSITE_H */