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// SPDX-License-Identifier: GPL-2.0+
* 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 <linux/bcd.h>
#include <linux/version.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <linux/log2.h>
#include <linux/configfs.h>
* USB function drivers should return USB_GADGET_DELAYED_STATUS if they
* wish to delay the data/status stages of the control transfer till they
* are ready. The control transfer will then be kept from completing till
* all the function drivers that requested for USB_GADGET_DELAYED_STAUS
* invoke usb_composite_setup_continue().
#define USB_GADGET_DELAYED_STATUS 0x7fff /* Impossibly large value */
/* big enough to hold our biggest descriptor */
#define USB_COMP_EP0_BUFSIZ 4096
/* OS feature descriptor length <= 4kB */
#define USB_MS_TO_HS_INTERVAL(x) (ilog2((x * 1000 / 125)) + 1)
struct usb_configuration;
* struct usb_os_desc_ext_prop - describes one "Extended Property"
* @entry: used to keep a list of extended properties
* @type: Extended Property type
* @name_len: Extended Property unicode name length, including terminating '\0'
* @name: Extended Property name
* @data_len: Length of Extended Property blob (for unicode store double len)
* @data: Extended Property blob
* @item: Represents this Extended Property in configfs
struct usb_os_desc_ext_prop {
struct list_head entry;
u8 type;
int name_len;
char *name;
int data_len;
char *data;
struct config_item item;
* struct usb_os_desc - describes OS descriptors associated with one interface
* @ext_compat_id: 16 bytes of "Compatible ID" and "Subcompatible ID"
* @ext_prop: Extended Properties list
* @ext_prop_len: Total length of Extended Properties blobs
* @ext_prop_count: Number of Extended Properties
* @opts_mutex: Optional mutex protecting config data of a usb_function_instance
* @group: Represents OS descriptors associated with an interface in configfs
* @owner: Module associated with this OS descriptor
struct usb_os_desc {
char *ext_compat_id;
struct list_head ext_prop;
int ext_prop_len;
int ext_prop_count;
struct mutex *opts_mutex;
struct config_group group;
struct module *owner;
* struct usb_os_desc_table - describes OS descriptors associated with one
* interface of a usb_function
* @if_id: Interface id
* @os_desc: "Extended Compatibility ID" and "Extended Properties" of the
* interface
* Each interface can have at most one "Extended Compatibility ID" and a
* number of "Extended Properties".
struct usb_os_desc_table {
int if_id;
struct usb_os_desc *os_desc;
* 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
* @fs_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.
* @ss_descriptors: Table of super speed descriptors, using interface and
* string identifiers assigned during @bind(). If this
* pointer is null after initiation, the function will not
* be available at super speed.
* @ssp_descriptors: Table of super speed plus descriptors, using
* interface and string identifiers assigned during @bind(). If
* this pointer is null after initiation, the function will not
* be available at super speed plus.
* @config: assigned when @usb_add_function() is called; this is the
* configuration with which this function is associated.
* @os_desc_table: Table of (interface id, os descriptors) pairs. The function
* can expose more than one interface. If an interface is a member of
* an IAD, only the first interface of IAD has its entry in the table.
* @os_desc_n: Number of entries in os_desc_table
* @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.
* @free_func: free the struct usb_function.
* @mod: (internal) points to the module that created this structure.
* @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.
* @req_match: Tests if a given class request can be handled by this function.
* @suspend: Notifies functions when the host stops sending USB traffic.
* @resume: Notifies functions when the host restarts USB traffic.
* @get_status: Returns function status as a reply to
* GetStatus() request when the recipient is Interface.
* @func_suspend: callback to be called when
* SetFeature(FUNCTION_SUSPEND) is reseived
* 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 **fs_descriptors;
struct usb_descriptor_header **hs_descriptors;
struct usb_descriptor_header **ss_descriptors;
struct usb_descriptor_header **ssp_descriptors;
struct usb_configuration *config;
struct usb_os_desc_table *os_desc_table;
unsigned os_desc_n;
/* 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 *);
void (*free_func)(struct usb_function *f);
struct module *mod;
/* 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 *);
bool (*req_match)(struct usb_function *,
const struct usb_ctrlrequest *,
bool config0);
void (*suspend)(struct usb_function *);
void (*resume)(struct usb_function *);
/* USB 3.0 additions */
int (*get_status)(struct usb_function *);
int (*func_suspend)(struct usb_function *,
u8 suspend_opt);
/* private: */
/* internals */
struct list_head list;
DECLARE_BITMAP(endpoints, 32);
const struct usb_function_instance *fi;
unsigned int bind_deactivated:1;
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 *);
int config_ep_by_speed_and_alt(struct usb_gadget *g, struct usb_function *f,
struct usb_ep *_ep, u8 alt);
int config_ep_by_speed(struct usb_gadget *g, struct usb_function *f,
struct usb_ep *_ep);
#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.
* @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.
* @MaxPower: Power consumption in mA. Used to compute bMaxPower in the
* configuration descriptor after considering the bus speed.
* @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 independent 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: unbind/setup */
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;
u16 MaxPower;
struct usb_composite_dev *cdev;
/* private: */
/* internals */
struct list_head list;
struct list_head functions;
u8 next_interface_id;
unsigned superspeed:1;
unsigned highspeed:1;
unsigned fullspeed:1;
unsigned superspeed_plus:1;
struct usb_function *interface[MAX_CONFIG_INTERFACES];
int usb_add_config(struct usb_composite_dev *,
struct usb_configuration *,
int (*)(struct usb_configuration *));
void usb_remove_config(struct usb_composite_dev *,
struct usb_configuration *);
/* predefined index for usb_composite_driver */
enum {
* 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. Note: The first entries
* are predefined. The first entry that may be used is
* @max_speed: Highest speed the driver supports.
* @needs_serial: set to 1 if the gadget needs userspace to provide
* a serial number. If one is not provided, warning will be printed.
* @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
* @gadget_driver: Gadget driver controlling this driver
* 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;
enum usb_device_speed max_speed;
unsigned needs_serial:1;
int (*bind)(struct usb_composite_dev *cdev);
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 *);
struct usb_gadget_driver gadget_driver;
extern int usb_composite_probe(struct usb_composite_driver *driver);
extern void usb_composite_unregister(struct usb_composite_driver *driver);
* module_usb_composite_driver() - Helper macro for registering a USB gadget
* composite driver
* @__usb_composite_driver: usb_composite_driver struct
* Helper macro for USB gadget composite drivers which do not do anything
* special in module init/exit. This eliminates a lot of boilerplate. Each
* module may only use this macro once, and calling it replaces module_init()
* and module_exit()
#define module_usb_composite_driver(__usb_composite_driver) \
module_driver(__usb_composite_driver, usb_composite_probe, \
extern void usb_composite_setup_continue(struct usb_composite_dev *cdev);
extern int composite_dev_prepare(struct usb_composite_driver *composite,
struct usb_composite_dev *cdev);
extern int composite_os_desc_req_prepare(struct usb_composite_dev *cdev,
struct usb_ep *ep0);
void composite_dev_cleanup(struct usb_composite_dev *cdev);
static inline struct usb_composite_driver *to_cdriver(
struct usb_gadget_driver *gdrv)
return container_of(gdrv, struct usb_composite_driver, gadget_driver);
#define OS_STRING_IDX 0xEE
* struct usb_composite_dev - represents one composite usb gadget
* @gadget: read-only, abstracts the gadget's usb peripheral controller
* @req: used for control responses; buffer is pre-allocated
* @os_desc_req: used for OS descriptors responses; buffer is pre-allocated
* @config: the currently active configuration
* @qw_sign: qwSignature part of the OS string
* @b_vendor_code: bMS_VendorCode part of the OS string
* @use_os_string: false by default, interested gadgets set it
* @os_desc_config: the configuration to be used with OS descriptors
* @setup_pending: true when setup request is queued but not completed
* @os_desc_pending: true when os_desc request is queued but not completed
* 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;
struct usb_request *os_desc_req;
struct usb_configuration *config;
/* OS String is a custom (yet popular) extension to the USB standard. */
u8 qw_sign[OS_STRING_QW_SIGN_LEN];
u8 b_vendor_code;
struct usb_configuration *os_desc_config;
unsigned int use_os_string:1;
/* private: */
/* internals */
unsigned int suspended:1;
struct usb_device_descriptor desc;
struct list_head configs;
struct list_head gstrings;
struct usb_composite_driver *driver;
u8 next_string_id;
char *def_manufacturer;
/* the gadget driver won't enable the data pullup
* while the deactivation count is nonzero.
unsigned deactivations;
/* the composite driver won't complete the control transfer's
* data/status stages till delayed_status is zero.
int delayed_status;
/* protects deactivations and delayed_status counts*/
spinlock_t lock;
/* public: */
unsigned int setup_pending:1;
unsigned int os_desc_pending:1;
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 struct usb_string *usb_gstrings_attach(struct usb_composite_dev *cdev,
struct usb_gadget_strings **sp, unsigned n_strings);
extern int usb_string_ids_n(struct usb_composite_dev *c, unsigned n);
extern void composite_disconnect(struct usb_gadget *gadget);
extern void composite_reset(struct usb_gadget *gadget);
extern int composite_setup(struct usb_gadget *gadget,
const struct usb_ctrlrequest *ctrl);
extern void composite_suspend(struct usb_gadget *gadget);
extern void composite_resume(struct usb_gadget *gadget);
* Some systems will need runtime overrides for the product identifiers
* published in the device descriptor, either numbers or strings or both.
* String parameters are in UTF-8 (superset of ASCII's 7 bit characters).
struct usb_composite_overwrite {
u16 idVendor;
u16 idProduct;
u16 bcdDevice;
char *serial_number;
char *manufacturer;
char *product;
static struct usb_composite_overwrite coverwrite; \
module_param_named(idVendor, coverwrite.idVendor, ushort, S_IRUGO); \
MODULE_PARM_DESC(idVendor, "USB Vendor ID"); \
module_param_named(idProduct, coverwrite.idProduct, ushort, S_IRUGO); \
MODULE_PARM_DESC(idProduct, "USB Product ID"); \
module_param_named(bcdDevice, coverwrite.bcdDevice, ushort, S_IRUGO); \
MODULE_PARM_DESC(bcdDevice, "USB Device version (BCD)"); \
module_param_named(iSerialNumber, coverwrite.serial_number, charp, \
MODULE_PARM_DESC(iSerialNumber, "SerialNumber string"); \
module_param_named(iManufacturer, coverwrite.manufacturer, charp, \
MODULE_PARM_DESC(iManufacturer, "USB Manufacturer string"); \
module_param_named(iProduct, coverwrite.product, charp, S_IRUGO); \
MODULE_PARM_DESC(iProduct, "USB Product string")
void usb_composite_overwrite_options(struct usb_composite_dev *cdev,
struct usb_composite_overwrite *covr);
static inline u16 get_default_bcdDevice(void)
u16 bcdDevice;
bcdDevice = bin2bcd(LINUX_VERSION_MAJOR) << 8;
bcdDevice |= bin2bcd(LINUX_VERSION_PATCHLEVEL);
return bcdDevice;
struct usb_function_driver {
const char *name;
struct module *mod;
struct list_head list;
struct usb_function_instance *(*alloc_inst)(void);
struct usb_function *(*alloc_func)(struct usb_function_instance *inst);
struct usb_function_instance {
struct config_group group;
struct list_head cfs_list;
struct usb_function_driver *fd;
int (*set_inst_name)(struct usb_function_instance *inst,
const char *name);
void (*free_func_inst)(struct usb_function_instance *inst);
void usb_function_unregister(struct usb_function_driver *f);
int usb_function_register(struct usb_function_driver *newf);
void usb_put_function_instance(struct usb_function_instance *fi);
void usb_put_function(struct usb_function *f);
struct usb_function_instance *usb_get_function_instance(const char *name);
struct usb_function *usb_get_function(struct usb_function_instance *fi);
struct usb_configuration *usb_get_config(struct usb_composite_dev *cdev,
int val);
int usb_add_config_only(struct usb_composite_dev *cdev,
struct usb_configuration *config);
void usb_remove_function(struct usb_configuration *c, struct usb_function *f);
#define DECLARE_USB_FUNCTION(_name, _inst_alloc, _func_alloc) \
static struct usb_function_driver _name ## usb_func = { \
.name = __stringify(_name), \
.mod = THIS_MODULE, \
.alloc_inst = _inst_alloc, \
.alloc_func = _func_alloc, \
}; \
#define DECLARE_USB_FUNCTION_INIT(_name, _inst_alloc, _func_alloc) \
DECLARE_USB_FUNCTION(_name, _inst_alloc, _func_alloc) \
static int __init _name ## mod_init(void) \
{ \
return usb_function_register(&_name ## usb_func); \
} \
static void __exit _name ## mod_exit(void) \
{ \
usb_function_unregister(&_name ## usb_func); \
} \
module_init(_name ## mod_init); \
module_exit(_name ## mod_exit)
/* messaging utils */
#define DBG(d, fmt, args...) \
dev_dbg(&(d)->gadget->dev , fmt , ## args)
#define VDBG(d, fmt, args...) \
dev_vdbg(&(d)->gadget->dev , fmt , ## args)
#define ERROR(d, fmt, args...) \
dev_err(&(d)->gadget->dev , fmt , ## args)
#define WARNING(d, fmt, args...) \
dev_warn(&(d)->gadget->dev , fmt , ## args)
#define INFO(d, fmt, args...) \
dev_info(&(d)->gadget->dev , fmt , ## args)
#endif /* __LINUX_USB_COMPOSITE_H */