include/linux/usb/composite.h

   1 /*
   2  * composite.h -- framework for usb gadgets which are composite devices
   3  *
   4  * Copyright (C) 2006-2008 David Brownell
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19  */
  20
  21 #ifndef __LINUX_USB_COMPOSITE_H
  22 #define __LINUX_USB_COMPOSITE_H
  23
  24 /*
  25  * This framework is an optional layer on top of the USB Gadget interface,
  26  * making it easier to build (a) Composite devices, supporting multiple
  27  * functions within any single configuration, and (b) Multi-configuration
  28  * devices, also supporting multiple functions but without necessarily
  29  * having more than one function per configuration.
  30  *
  31  * Example:  a device with a single configuration supporting both network
  32  * link and mass storage functions is a composite device.  Those functions
  33  * might alternatively be packaged in individual configurations, but in
  34  * the composite model the host can use both functions at the same time.
  35  */
  36
  37 #include <linux/usb/ch9.h>
  38 #include <linux/usb/gadget.h>
  39
  40
  41 struct usb_configuration;
  42
  43 /**
  44  * struct usb_function - describes one function of a configuration
  45  * @name: For diagnostics, identifies the function.
  46  * @strings: tables of strings, keyed by identifiers assigned during bind()
  47  *      and by language IDs provided in control requests
  48  * @descriptors: Table of full (or low) speed descriptors, using interface and
  49  *      string identifiers assigned during @bind().  If this pointer is null,
  50  *      the function will not be available at full speed (or at low speed).
  51  * @hs_descriptors: Table of high speed descriptors, using interface and
  52  *      string identifiers assigned during @bind().  If this pointer is null,
  53  *      the function will not be available at high speed.
  54  * @config: assigned when @usb_add_function() is called; this is the
  55  *      configuration with which this function is associated.
  56  * @bind: Before the gadget can register, all of its functions bind() to the
  57  *      available resources including string and interface identifiers used
  58  *      in interface or class descriptors; endpoints; I/O buffers; and so on.
  59  * @unbind: Reverses @bind; called as a side effect of unregistering the
  60  *      driver which added this function.
  61  * @set_alt: (REQUIRED) Reconfigures altsettings; function drivers may
  62  *      initialize usb_ep.driver data at this time (when it is used).
  63  *      Note that setting an interface to its current altsetting resets
  64  *      interface state, and that all interfaces have a disabled state.
  65  * @get_alt: Returns the active altsetting.  If this is not provided,
  66  *      then only altsetting zero is supported.
  67  * @disable: (REQUIRED) Indicates the function should be disabled.  Reasons
  68  *      include host resetting or reconfiguring the gadget, and disconnection.
  69  * @setup: Used for interface-specific control requests.
  70  * @suspend: Notifies functions when the host stops sending USB traffic.
  71  * @resume: Notifies functions when the host restarts USB traffic.
  72  *
  73  * A single USB function uses one or more interfaces, and should in most
  74  * cases support operation at both full and high speeds.  Each function is
  75  * associated by @usb_add_function() with a one configuration; that function
  76  * causes @bind() to be called so resources can be allocated as part of
  77  * setting up a gadget driver.  Those resources include endpoints, which
  78  * should be allocated using @usb_ep_autoconfig().
  79  *
  80  * To support dual speed operation, a function driver provides descriptors
  81  * for both high and full speed operation.  Except in rare cases that don't
  82  * involve bulk endpoints, each speed needs different endpoint descriptors.
  83  *
  84  * Function drivers choose their own strategies for managing instance data.
  85  * The simplest strategy just declares it "static', which means the function
  86  * can only be activated once.  If the function needs to be exposed in more
  87  * than one configuration at a given speed, it needs to support multiple
  88  * usb_function structures (one for each configuration).
  89  *
  90  * A more complex strategy might encapsulate a @usb_function structure inside
  91  * a driver-specific instance structure to allows multiple activations.  An
  92  * example of multiple activations might be a CDC ACM function that supports
  93  * two or more distinct instances within the same configuration, providing
  94  * several independent logical data links to a USB host.
  95  */
  96 struct usb_function {
  97         const char                      *name;
  98         struct usb_gadget_strings       **strings;
  99         struct usb_descriptor_header    **descriptors;
 100         struct usb_descriptor_header    **hs_descriptors;
 101
 102         struct usb_configuration        *config;
 103
 104         /* REVISIT:  bind() functions can be marked __init, which
 105          * makes trouble for section mismatch analysis.  See if
 106          * we can't restructure things to avoid mismatching.
 107          * Related:  unbind() may kfree() but bind() won't...
 108          */
 109
 110         /* configuration management:  bind/unbind */
 111         int                     (*bind)(struct usb_configuration *,
 112                                         struct usb_function *);
 113         void                    (*unbind)(struct usb_configuration *,
 114                                         struct usb_function *);
 115
 116         /* runtime state management */
 117         int                     (*set_alt)(struct usb_function *,
 118                                         unsigned interface, unsigned alt);
 119         int                     (*get_alt)(struct usb_function *,
 120                                         unsigned interface);
 121         void                    (*disable)(struct usb_function *);
 122         int                     (*setup)(struct usb_function *,
 123                                         const struct usb_ctrlrequest *);
 124         void                    (*suspend)(struct usb_function *);
 125         void                    (*resume)(struct usb_function *);
 126
 127         /* private: */
 128         /* internals */
 129         struct list_head                list;
 130 };
 131
 132 int usb_add_function(struct usb_configuration *, struct usb_function *);
 133
 134 int usb_function_deactivate(struct usb_function *);
 135 int usb_function_activate(struct usb_function *);
 136
 137 int usb_interface_id(struct usb_configuration *, struct usb_function *);
 138
 139 /**
 140  * ep_choose - select descriptor endpoint at current device speed
 141  * @g: gadget, connected and running at some speed
 142  * @hs: descriptor to use for high speed operation
 143  * @fs: descriptor to use for full or low speed operation
 144  */
 145 static inline struct usb_endpoint_descriptor *
 146 ep_choose(struct usb_gadget *g, struct usb_endpoint_descriptor *hs,
 147                 struct usb_endpoint_descriptor *fs)
 148 {
 149         if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH)
 150                 return hs;
 151         return fs;
 152 }
 153
 154 #define MAX_CONFIG_INTERFACES           16      /* arbitrary; max 255 */
 155
 156 /**
 157  * struct usb_configuration - represents one gadget configuration
 158  * @label: For diagnostics, describes the configuration.
 159  * @strings: Tables of strings, keyed by identifiers assigned during @bind()
 160  *      and by language IDs provided in control requests.
 161  * @descriptors: Table of descriptors preceding all function descriptors.
 162  *      Examples include OTG and vendor-specific descriptors.
 163  * @bind: Called from @usb_add_config() to allocate resources unique to this
 164  *      configuration and to call @usb_add_function() for each function used.
 165  * @unbind: Reverses @bind; called as a side effect of unregistering the
 166  *      driver which added this configuration.
 167  * @setup: Used to delegate control requests that aren't handled by standard
 168  *      device infrastructure or directed at a specific interface.
 169  * @bConfigurationValue: Copied into configuration descriptor.
 170  * @iConfiguration: Copied into configuration descriptor.
 171  * @bmAttributes: Copied into configuration descriptor.
 172  * @bMaxPower: Copied into configuration descriptor.
 173  * @cdev: assigned by @usb_add_config() before calling @bind(); this is
 174  *      the device associated with this configuration.
 175  *
 176  * Configurations are building blocks for gadget drivers structured around
 177  * function drivers.  Simple USB gadgets require only one function and one
 178  * configuration, and handle dual-speed hardware by always providing the same
 179  * functionality.  Slightly more complex gadgets may have more than one
 180  * single-function configuration at a given speed; or have configurations
 181  * that only work at one speed.
 182  *
 183  * Composite devices are, by definition, ones with configurations which
 184  * include more than one function.
 185  *
 186  * The lifecycle of a usb_configuration includes allocation, initialization
 187  * of the fields described above, and calling @usb_add_config() to set up
 188  * internal data and bind it to a specific device.  The configuration's
 189  * @bind() method is then used to initialize all the functions and then
 190  * call @usb_add_function() for them.
 191  *
 192  * Those functions would normally be independant of each other, but that's
 193  * not mandatory.  CDC WMC devices are an example where functions often
 194  * depend on other functions, with some functions subsidiary to others.
 195  * Such interdependency may be managed in any way, so long as all of the
 196  * descriptors complete by the time the composite driver returns from
 197  * its bind() routine.
 198  */
 199 struct usb_configuration {
 200         const char                      *label;
 201         struct usb_gadget_strings       **strings;
 202         const struct usb_descriptor_header **descriptors;
 203
 204         /* REVISIT:  bind() functions can be marked __init, which
 205          * makes trouble for section mismatch analysis.  See if
 206          * we can't restructure things to avoid mismatching...
 207          */
 208
 209         /* configuration management:  bind/unbind */
 210         int                     (*bind)(struct usb_configuration *);
 211         void                    (*unbind)(struct usb_configuration *);
 212         int                     (*setup)(struct usb_configuration *,
 213                                         const struct usb_ctrlrequest *);
 214
 215         /* fields in the config descriptor */
 216         u8                      bConfigurationValue;
 217         u8                      iConfiguration;
 218         u8                      bmAttributes;
 219         u8                      bMaxPower;
 220
 221         struct usb_composite_dev        *cdev;
 222
 223         /* private: */
 224         /* internals */
 225         struct list_head        list;
 226         struct list_head        functions;
 227         u8                      next_interface_id;
 228         unsigned                highspeed:1;
 229         unsigned                fullspeed:1;
 230         struct usb_function     *interface[MAX_CONFIG_INTERFACES];
 231 };
 232
 233 int usb_add_config(struct usb_composite_dev *,
 234                 struct usb_configuration *);
 235
 236 /**
 237  * struct usb_composite_driver - groups configurations into a gadget
 238  * @name: For diagnostics, identifies the driver.
 239  * @dev: Template descriptor for the device, including default device
 240  *      identifiers.
 241  * @strings: tables of strings, keyed by identifiers assigned during bind()
 242  *      and language IDs provided in control requests
 243  * @bind: (REQUIRED) Used to allocate resources that are shared across the
 244  *      whole device, such as string IDs, and add its configurations using
 245  *      @usb_add_config().  This may fail by returning a negative errno
 246  *      value; it should return zero on successful initialization.
 247  * @unbind: Reverses @bind(); called as a side effect of unregistering
 248  *      this driver.
 249  * @suspend: Notifies when the host stops sending USB traffic,
 250  *      after function notifications
 251  * @resume: Notifies configuration when the host restarts USB traffic,
 252  *      before function notifications
 253  *
 254  * Devices default to reporting self powered operation.  Devices which rely
 255  * on bus powered operation should report this in their @bind() method.
 256  *
 257  * Before returning from @bind, various fields in the template descriptor
 258  * may be overridden.  These include the idVendor/idProduct/bcdDevice values
 259  * normally to bind the appropriate host side driver, and the three strings
 260  * (iManufacturer, iProduct, iSerialNumber) normally used to provide user
 261  * meaningful device identifiers.  (The strings will not be defined unless
 262  * they are defined in @dev and @strings.)  The correct ep0 maxpacket size
 263  * is also reported, as defined by the underlying controller driver.
 264  */
 265 struct usb_composite_driver {
 266         const char                              *name;
 267         const struct usb_device_descriptor      *dev;
 268         struct usb_gadget_strings               **strings;
 269
 270         /* REVISIT:  bind() functions can be marked __init, which
 271          * makes trouble for section mismatch analysis.  See if
 272          * we can't restructure things to avoid mismatching...
 273          */
 274
 275         int                     (*bind)(struct usb_composite_dev *);
 276         int                     (*unbind)(struct usb_composite_dev *);
 277
 278         /* global suspend hooks */
 279         void                    (*suspend)(struct usb_composite_dev *);
 280         void                    (*resume)(struct usb_composite_dev *);
 281 };
 282
 283 extern int usb_composite_register(struct usb_composite_driver *);
 284 extern void usb_composite_unregister(struct usb_composite_driver *);
 285
 286
 287 /**
 288  * struct usb_composite_device - represents one composite usb gadget
 289  * @gadget: read-only, abstracts the gadget's usb peripheral controller
 290  * @req: used for control responses; buffer is pre-allocated
 291  * @bufsiz: size of buffer pre-allocated in @req
 292  * @config: the currently active configuration
 293  *
 294  * One of these devices is allocated and initialized before the
 295  * associated device driver's bind() is called.
 296  *
 297  * OPEN ISSUE:  it appears that some WUSB devices will need to be
 298  * built by combining a normal (wired) gadget with a wireless one.
 299  * This revision of the gadget framework should probably try to make
 300  * sure doing that won't hurt too much.
 301  *
 302  * One notion for how to handle Wireless USB devices involves:
 303  * (a) a second gadget here, discovery mechanism TBD, but likely
 304  *     needing separate "register/unregister WUSB gadget" calls;
 305  * (b) updates to usb_gadget to include flags "is it wireless",
 306  *     "is it wired", plus (presumably in a wrapper structure)
 307  *     bandgroup and PHY info;
 308  * (c) presumably a wireless_ep wrapping a usb_ep, and reporting
 309  *     wireless-specific parameters like maxburst and maxsequence;
 310  * (d) configurations that are specific to wireless links;
 311  * (e) function drivers that understand wireless configs and will
 312  *     support wireless for (additional) function instances;
 313  * (f) a function to support association setup (like CBAF), not
 314  *     necessarily requiring a wireless adapter;
 315  * (g) composite device setup that can create one or more wireless
 316  *     configs, including appropriate association setup support;
 317  * (h) more, TBD.
 318  */
 319 struct usb_composite_dev {
 320         struct usb_gadget               *gadget;
 321         struct usb_request              *req;
 322         unsigned                        bufsiz;
 323
 324         struct usb_configuration        *config;
 325
 326         /* private: */
 327         /* internals */
 328         struct usb_device_descriptor    desc;
 329         struct list_head                configs;
 330         struct usb_composite_driver     *driver;
 331         u8                              next_string_id;
 332
 333         /* the gadget driver won't enable the data pullup
 334          * while the deactivation count is nonzero.
 335          */
 336         unsigned                        deactivations;
 337
 338         /* protects at least deactivation count */
 339         spinlock_t                      lock;
 340 };
 341
 342 extern int usb_string_id(struct usb_composite_dev *c);
 343
 344 /* messaging utils */
 345 #define DBG(d, fmt, args...) \
 346         dev_dbg(&(d)->gadget->dev , fmt , ## args)
 347 #define VDBG(d, fmt, args...) \
 348         dev_vdbg(&(d)->gadget->dev , fmt , ## args)
 349 #define ERROR(d, fmt, args...) \
 350         dev_err(&(d)->gadget->dev , fmt , ## args)
 351 #define WARNING(d, fmt, args...) \
 352         dev_warn(&(d)->gadget->dev , fmt , ## args)
 353 #define INFO(d, fmt, args...) \
 354         dev_info(&(d)->gadget->dev , fmt , ## args)
 355
 356 #endif  /* __LINUX_USB_COMPOSITE_H */