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Diffstat (limited to 'include/linux/usb/gadget.h')
| -rw-r--r-- | include/linux/usb/gadget.h | 866 |
1 files changed, 866 insertions, 0 deletions
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h new file mode 100644 index 00000000000..46705e91573 --- /dev/null +++ b/include/linux/usb/gadget.h @@ -0,0 +1,866 @@ +/* + * <linux/usb/gadget.h> + * + * We call the USB code inside a Linux-based peripheral device a "gadget" + * driver, except for the hardware-specific bus glue. One USB host can + * master many USB gadgets, but the gadgets are only slaved to one host. + * + * + * (C) Copyright 2002-2004 by David Brownell + * All Rights Reserved. + * + * This software is licensed under the GNU GPL version 2. + */ + +#ifndef __LINUX_USB_GADGET_H +#define __LINUX_USB_GADGET_H + +#ifdef __KERNEL__ + +struct usb_ep; + +/** + * struct usb_request - describes one i/o request + * @buf: Buffer used for data. Always provide this; some controllers + * only use PIO, or don't use DMA for some endpoints. + * @dma: DMA address corresponding to 'buf'. If you don't set this + * field, and the usb controller needs one, it is responsible + * for mapping and unmapping the buffer. + * @length: Length of that data + * @no_interrupt: If true, hints that no completion irq is needed. + * Helpful sometimes with deep request queues that are handled + * directly by DMA controllers. + * @zero: If true, when writing data, makes the last packet be "short" + * by adding a zero length packet as needed; + * @short_not_ok: When reading data, makes short packets be + * treated as errors (queue stops advancing till cleanup). + * @complete: Function called when request completes, so this request and + * its buffer may be re-used. + * Reads terminate with a short packet, or when the buffer fills, + * whichever comes first. When writes terminate, some data bytes + * will usually still be in flight (often in a hardware fifo). + * Errors (for reads or writes) stop the queue from advancing + * until the completion function returns, so that any transfers + * invalidated by the error may first be dequeued. + * @context: For use by the completion callback + * @list: For use by the gadget driver. + * @status: Reports completion code, zero or a negative errno. + * Normally, faults block the transfer queue from advancing until + * the completion callback returns. + * Code "-ESHUTDOWN" indicates completion caused by device disconnect, + * or when the driver disabled the endpoint. + * @actual: Reports bytes transferred to/from the buffer. For reads (OUT + * transfers) this may be less than the requested length. If the + * short_not_ok flag is set, short reads are treated as errors + * even when status otherwise indicates successful completion. + * Note that for writes (IN transfers) some data bytes may still + * reside in a device-side FIFO when the request is reported as + * complete. + * + * These are allocated/freed through the endpoint they're used with. The + * hardware's driver can add extra per-request data to the memory it returns, + * which often avoids separate memory allocations (potential failures), + * later when the request is queued. + * + * Request flags affect request handling, such as whether a zero length + * packet is written (the "zero" flag), whether a short read should be + * treated as an error (blocking request queue advance, the "short_not_ok" + * flag), or hinting that an interrupt is not required (the "no_interrupt" + * flag, for use with deep request queues). + * + * Bulk endpoints can use any size buffers, and can also be used for interrupt + * transfers. interrupt-only endpoints can be much less functional. + */ + // NOTE this is analagous to 'struct urb' on the host side, + // except that it's thinner and promotes more pre-allocation. + +struct usb_request { + void *buf; + unsigned length; + dma_addr_t dma; + + unsigned no_interrupt:1; + unsigned zero:1; + unsigned short_not_ok:1; + + void (*complete)(struct usb_ep *ep, + struct usb_request *req); + void *context; + struct list_head list; + + int status; + unsigned actual; +}; + +/*-------------------------------------------------------------------------*/ + +/* endpoint-specific parts of the api to the usb controller hardware. + * unlike the urb model, (de)multiplexing layers are not required. + * (so this api could slash overhead if used on the host side...) + * + * note that device side usb controllers commonly differ in how many + * endpoints they support, as well as their capabilities. + */ +struct usb_ep_ops { + int (*enable) (struct usb_ep *ep, + const struct usb_endpoint_descriptor *desc); + int (*disable) (struct usb_ep *ep); + + struct usb_request *(*alloc_request) (struct usb_ep *ep, + gfp_t gfp_flags); + void (*free_request) (struct usb_ep *ep, struct usb_request *req); + + int (*queue) (struct usb_ep *ep, struct usb_request *req, + gfp_t gfp_flags); + int (*dequeue) (struct usb_ep *ep, struct usb_request *req); + + int (*set_halt) (struct usb_ep *ep, int value); + int (*fifo_status) (struct usb_ep *ep); + void (*fifo_flush) (struct usb_ep *ep); +}; + +/** + * struct usb_ep - device side representation of USB endpoint + * @name:identifier for the endpoint, such as "ep-a" or "ep9in-bulk" + * @ops: Function pointers used to access hardware-specific operations. + * @ep_list:the gadget's ep_list holds all of its endpoints + * @maxpacket:The maximum packet size used on this endpoint. The initial + * value can sometimes be reduced (hardware allowing), according to + * the endpoint descriptor used to configure the endpoint. + * @driver_data:for use by the gadget driver. all other fields are + * read-only to gadget drivers. + * + * the bus controller driver lists all the general purpose endpoints in + * gadget->ep_list. the control endpoint (gadget->ep0) is not in that list, + * and is accessed only in response to a driver setup() callback. + */ +struct usb_ep { + void *driver_data; + + const char *name; + const struct usb_ep_ops *ops; + struct list_head ep_list; + unsigned maxpacket:16; +}; + +/*-------------------------------------------------------------------------*/ + +/** + * usb_ep_enable - configure endpoint, making it usable + * @ep:the endpoint being configured. may not be the endpoint named "ep0". + * drivers discover endpoints through the ep_list of a usb_gadget. + * @desc:descriptor for desired behavior. caller guarantees this pointer + * remains valid until the endpoint is disabled; the data byte order + * is little-endian (usb-standard). + * + * when configurations are set, or when interface settings change, the driver + * will enable or disable the relevant endpoints. while it is enabled, an + * endpoint may be used for i/o until the driver receives a disconnect() from + * the host or until the endpoint is disabled. + * + * the ep0 implementation (which calls this routine) must ensure that the + * hardware capabilities of each endpoint match the descriptor provided + * for it. for example, an endpoint named "ep2in-bulk" would be usable + * for interrupt transfers as well as bulk, but it likely couldn't be used + * for iso transfers or for endpoint 14. some endpoints are fully + * configurable, with more generic names like "ep-a". (remember that for + * USB, "in" means "towards the USB master".) + * + * returns zero, or a negative error code. + */ +static inline int +usb_ep_enable (struct usb_ep *ep, const struct usb_endpoint_descriptor *desc) +{ + return ep->ops->enable (ep, desc); +} + +/** + * usb_ep_disable - endpoint is no longer usable + * @ep:the endpoint being unconfigured. may not be the endpoint named "ep0". + * + * no other task may be using this endpoint when this is called. + * any pending and uncompleted requests will complete with status + * indicating disconnect (-ESHUTDOWN) before this call returns. + * gadget drivers must call usb_ep_enable() again before queueing + * requests to the endpoint. + * + * returns zero, or a negative error code. + */ +static inline int +usb_ep_disable (struct usb_ep *ep) +{ + return ep->ops->disable (ep); +} + +/** + * usb_ep_alloc_request - allocate a request object to use with this endpoint + * @ep:the endpoint to be used with with the request + * @gfp_flags:GFP_* flags to use + * + * Request objects must be allocated with this call, since they normally + * need controller-specific setup and may even need endpoint-specific + * resources such as allocation of DMA descriptors. + * Requests may be submitted with usb_ep_queue(), and receive a single + * completion callback. Free requests with usb_ep_free_request(), when + * they are no longer needed. + * + * Returns the request, or null if one could not be allocated. + */ +static inline struct usb_request * +usb_ep_alloc_request (struct usb_ep *ep, gfp_t gfp_flags) +{ + return ep->ops->alloc_request (ep, gfp_flags); +} + +/** + * usb_ep_free_request - frees a request object + * @ep:the endpoint associated with the request + * @req:the request being freed + * + * Reverses the effect of usb_ep_alloc_request(). + * Caller guarantees the request is not queued, and that it will + * no longer be requeued (or otherwise used). + */ +static inline void +usb_ep_free_request (struct usb_ep *ep, struct usb_request *req) +{ + ep->ops->free_request (ep, req); +} + +/** + * usb_ep_queue - queues (submits) an I/O request to an endpoint. + * @ep:the endpoint associated with the request + * @req:the request being submitted + * @gfp_flags: GFP_* flags to use in case the lower level driver couldn't + * pre-allocate all necessary memory with the request. + * + * This tells the device controller to perform the specified request through + * that endpoint (reading or writing a buffer). When the request completes, + * including being canceled by usb_ep_dequeue(), the request's completion + * routine is called to return the request to the driver. Any endpoint + * (except control endpoints like ep0) may have more than one transfer + * request queued; they complete in FIFO order. Once a gadget driver + * submits a request, that request may not be examined or modified until it + * is given back to that driver through the completion callback. + * + * Each request is turned into one or more packets. The controller driver + * never merges adjacent requests into the same packet. OUT transfers + * will sometimes use data that's already buffered in the hardware. + * Drivers can rely on the fact that the first byte of the request's buffer + * always corresponds to the first byte of some USB packet, for both + * IN and OUT transfers. + * + * Bulk endpoints can queue any amount of data; the transfer is packetized + * automatically. The last packet will be short if the request doesn't fill it + * out completely. Zero length packets (ZLPs) should be avoided in portable + * protocols since not all usb hardware can successfully handle zero length + * packets. (ZLPs may be explicitly written, and may be implicitly written if + * the request 'zero' flag is set.) Bulk endpoints may also be used + * for interrupt transfers; but the reverse is not true, and some endpoints + * won't support every interrupt transfer. (Such as 768 byte packets.) + * + * Interrupt-only endpoints are less functional than bulk endpoints, for + * example by not supporting queueing or not handling buffers that are + * larger than the endpoint's maxpacket size. They may also treat data + * toggle differently. + * + * Control endpoints ... after getting a setup() callback, the driver queues + * one response (even if it would be zero length). That enables the + * status ack, after transfering data as specified in the response. Setup + * functions may return negative error codes to generate protocol stalls. + * (Note that some USB device controllers disallow protocol stall responses + * in some cases.) When control responses are deferred (the response is + * written after the setup callback returns), then usb_ep_set_halt() may be + * used on ep0 to trigger protocol stalls. + * + * For periodic endpoints, like interrupt or isochronous ones, the usb host + * arranges to poll once per interval, and the gadget driver usually will + * have queued some data to transfer at that time. + * + * Returns zero, or a negative error code. Endpoints that are not enabled + * report errors; errors will also be + * reported when the usb peripheral is disconnected. + */ +static inline int +usb_ep_queue (struct usb_ep *ep, struct usb_request *req, gfp_t gfp_flags) +{ + return ep->ops->queue (ep, req, gfp_flags); +} + +/** + * usb_ep_dequeue - dequeues (cancels, unlinks) an I/O request from an endpoint + * @ep:the endpoint associated with the request + * @req:the request being canceled + * + * if the request is still active on the endpoint, it is dequeued and its + * completion routine is called (with status -ECONNRESET); else a negative + * error code is returned. + * + * note that some hardware can't clear out write fifos (to unlink the request + * at the head of the queue) except as part of disconnecting from usb. such + * restrictions prevent drivers from supporting configuration changes, + * even to configuration zero (a "chapter 9" requirement). + */ +static inline int usb_ep_dequeue (struct usb_ep *ep, struct usb_request *req) +{ + return ep->ops->dequeue (ep, req); +} + +/** + * usb_ep_set_halt - sets the endpoint halt feature. + * @ep: the non-isochronous endpoint being stalled + * + * Use this to stall an endpoint, perhaps as an error report. + * Except for control endpoints, + * the endpoint stays halted (will not stream any data) until the host + * clears this feature; drivers may need to empty the endpoint's request + * queue first, to make sure no inappropriate transfers happen. + * + * Note that while an endpoint CLEAR_FEATURE will be invisible to the + * gadget driver, a SET_INTERFACE will not be. To reset endpoints for the + * current altsetting, see usb_ep_clear_halt(). When switching altsettings, + * it's simplest to use usb_ep_enable() or usb_ep_disable() for the endpoints. + * + * Returns zero, or a negative error code. On success, this call sets + * underlying hardware state that blocks data transfers. + * Attempts to halt IN endpoints will fail (returning -EAGAIN) if any + * transfer requests are still queued, or if the controller hardware + * (usually a FIFO) still holds bytes that the host hasn't collected. + */ +static inline int +usb_ep_set_halt (struct usb_ep *ep) +{ + return ep->ops->set_halt (ep, 1); +} + +/** + * usb_ep_clear_halt - clears endpoint halt, and resets toggle + * @ep:the bulk or interrupt endpoint being reset + * + * Use this when responding to the standard usb "set interface" request, + * for endpoints that aren't reconfigured, after clearing any other state + * in the endpoint's i/o queue. + * + * Returns zero, or a negative error code. On success, this call clears + * the underlying hardware state reflecting endpoint halt and data toggle. + * Note that some hardware can't support this request (like pxa2xx_udc), + * and accordingly can't correctly implement interface altsettings. + */ +static inline int +usb_ep_clear_halt (struct usb_ep *ep) +{ + return ep->ops->set_halt (ep, 0); +} + +/** + * usb_ep_fifo_status - returns number of bytes in fifo, or error + * @ep: the endpoint whose fifo status is being checked. + * + * FIFO endpoints may have "unclaimed data" in them in certain cases, + * such as after aborted transfers. Hosts may not have collected all + * the IN data written by the gadget driver (and reported by a request + * completion). The gadget driver may not have collected all the data + * written OUT to it by the host. Drivers that need precise handling for + * fault reporting or recovery may need to use this call. + * + * This returns the number of such bytes in the fifo, or a negative + * errno if the endpoint doesn't use a FIFO or doesn't support such + * precise handling. + */ +static inline int +usb_ep_fifo_status (struct usb_ep *ep) +{ + if (ep->ops->fifo_status) + return ep->ops->fifo_status (ep); + else + return -EOPNOTSUPP; +} + +/** + * usb_ep_fifo_flush - flushes contents of a fifo + * @ep: the endpoint whose fifo is being flushed. + * + * This call may be used to flush the "unclaimed data" that may exist in + * an endpoint fifo after abnormal transaction terminations. The call + * must never be used except when endpoint is not being used for any + * protocol translation. + */ +static inline void +usb_ep_fifo_flush (struct usb_ep *ep) +{ + if (ep->ops->fifo_flush) + ep->ops->fifo_flush (ep); +} + + +/*-------------------------------------------------------------------------*/ + +struct usb_gadget; + +/* the rest of the api to the controller hardware: device operations, + * which don't involve endpoints (or i/o). + */ +struct usb_gadget_ops { + int (*get_frame)(struct usb_gadget *); + int (*wakeup)(struct usb_gadget *); + int (*set_selfpowered) (struct usb_gadget *, int is_selfpowered); + int (*vbus_session) (struct usb_gadget *, int is_active); + int (*vbus_draw) (struct usb_gadget *, unsigned mA); + int (*pullup) (struct usb_gadget *, int is_on); + int (*ioctl)(struct usb_gadget *, + unsigned code, unsigned long param); +}; + +/** + * struct usb_gadget - represents a usb slave device + * @ops: Function pointers used to access hardware-specific operations. + * @ep0: Endpoint zero, used when reading or writing responses to + * driver setup() requests + * @ep_list: List of other endpoints supported by the device. + * @speed: Speed of current connection to USB host. + * @is_dualspeed: True if the controller supports both high and full speed + * operation. If it does, the gadget driver must also support both. + * @is_otg: True if the USB device port uses a Mini-AB jack, so that the + * gadget driver must provide a USB OTG descriptor. + * @is_a_peripheral: False unless is_otg, the "A" end of a USB cable + * is in the Mini-AB jack, and HNP has been used to switch roles + * so that the "A" device currently acts as A-Peripheral, not A-Host. + * @a_hnp_support: OTG device feature flag, indicating that the A-Host + * supports HNP at this port. + * @a_alt_hnp_support: OTG device feature flag, indicating that the A-Host + * only supports HNP on a different root port. + * @b_hnp_enable: OTG device feature flag, indicating that the A-Host + * enabled HNP support. + * @name: Identifies the controller hardware type. Used in diagnostics + * and sometimes configuration. + * @dev: Driver model state for this abstract device. + * + * Gadgets have a mostly-portable "gadget driver" implementing device + * functions, handling all usb configurations and interfaces. Gadget + * drivers talk to hardware-specific code indirectly, through ops vectors. + * That insulates the gadget driver from hardware details, and packages + * the hardware endpoints through generic i/o queues. The "usb_gadget" + * and "usb_ep" interfaces provide that insulation from the hardware. + * + * Except for the driver data, all fields in this structure are + * read-only to the gadget driver. That driver data is part of the + * "driver model" infrastructure in 2.6 (and later) kernels, and for + * earlier systems is grouped in a similar structure that's not known + * to the rest of the kernel. + * + * Values of the three OTG device feature flags are updated before the + * setup() call corresponding to USB_REQ_SET_CONFIGURATION, and before + * driver suspend() calls. They are valid only when is_otg, and when the + * device is acting as a B-Peripheral (so is_a_peripheral is false). + */ +struct usb_gadget { + /* readonly to gadget driver */ + const struct usb_gadget_ops *ops; + struct usb_ep *ep0; + struct list_head ep_list; /* of usb_ep */ + enum usb_device_speed speed; + unsigned is_dualspeed:1; + unsigned is_otg:1; + unsigned is_a_peripheral:1; + unsigned b_hnp_enable:1; + unsigned a_hnp_support:1; + unsigned a_alt_hnp_support:1; + const char *name; + struct device dev; +}; + +static inline void set_gadget_data (struct usb_gadget *gadget, void *data) + { dev_set_drvdata (&gadget->dev, data); } +static inline void *get_gadget_data (struct usb_gadget *gadget) + { return dev_get_drvdata (&gadget->dev); } + +/* iterates the non-control endpoints; 'tmp' is a struct usb_ep pointer */ +#define gadget_for_each_ep(tmp,gadget) \ + list_for_each_entry(tmp, &(gadget)->ep_list, ep_list) + + +/** + * gadget_is_dualspeed - return true iff the hardware handles high speed + * @gadget: controller that might support both high and full speeds + */ +static inline int gadget_is_dualspeed(struct usb_gadget *g) +{ +#ifdef CONFIG_USB_GADGET_DUALSPEED + /* runtime test would check "g->is_dualspeed" ... that might be + * useful to work around hardware bugs, but is mostly pointless + */ + return 1; +#else + return 0; +#endif +} + +/** + * gadget_is_otg - return true iff the hardware is OTG-ready + * @gadget: controller that might have a Mini-AB connector + * + * This is a runtime test, since kernels with a USB-OTG stack sometimes + * run on boards which only have a Mini-B (or Mini-A) connector. + */ +static inline int gadget_is_otg(struct usb_gadget *g) +{ +#ifdef CONFIG_USB_OTG + return g->is_otg; +#else + return 0; +#endif +} + + +/** + * usb_gadget_frame_number - returns the current frame number + * @gadget: controller that reports the frame number + * + * Returns the usb frame number, normally eleven bits from a SOF packet, + * or negative errno if this device doesn't support this capability. + */ +static inline int usb_gadget_frame_number (struct usb_gadget *gadget) +{ + return gadget->ops->get_frame (gadget); +} + +/** + * usb_gadget_wakeup - tries to wake up the host connected to this gadget + * @gadget: controller used to wake up the host + * + * Returns zero on success, else negative error code if the hardware + * doesn't support such attempts, or its support has not been enabled + * by the usb host. Drivers must return device descriptors that report + * their ability to support this, or hosts won't enable it. + * + * This may also try to use SRP to wake the host and start enumeration, + * even if OTG isn't otherwise in use. OTG devices may also start + * remote wakeup even when hosts don't explicitly enable it. + */ +static inline int usb_gadget_wakeup (struct usb_gadget *gadget) +{ + if (!gadget->ops->wakeup) + return -EOPNOTSUPP; + return gadget->ops->wakeup (gadget); +} + +/** + * usb_gadget_set_selfpowered - sets the device selfpowered feature. + * @gadget:the device being declared as self-powered + * + * this affects the device status reported by the hardware driver + * to reflect that it now has a local power supply. + * + * returns zero on success, else negative errno. + */ +static inline int +usb_gadget_set_selfpowered (struct usb_gadget *gadget) +{ + if (!gadget->ops->set_selfpowered) + return -EOPNOTSUPP; + return gadget->ops->set_selfpowered (gadget, 1); +} + +/** + * usb_gadget_clear_selfpowered - clear the device selfpowered feature. + * @gadget:the device being declared as bus-powered + * + * this affects the device status reported by the hardware driver. + * some hardware may not support bus-powered operation, in which + * case this feature's value can never change. + * + * returns zero on success, else negative errno. + */ +static inline int +usb_gadget_clear_selfpowered (struct usb_gadget *gadget) +{ + if (!gadget->ops->set_selfpowered) + return -EOPNOTSUPP; + return gadget->ops->set_selfpowered (gadget, 0); +} + +/** + * usb_gadget_vbus_connect - Notify controller that VBUS is powered + * @gadget:The device which now has VBUS power. + * + * This call is used by a driver for an external transceiver (or GPIO) + * that detects a VBUS power session starting. Common responses include + * resuming the controller, activating the D+ (or D-) pullup to let the + * host detect that a USB device is attached, and starting to draw power + * (8mA or possibly more, especially after SET_CONFIGURATION). + * + * Returns zero on success, else negative errno. + */ +static inline int +usb_gadget_vbus_connect(struct usb_gadget *gadget) +{ + if (!gadget->ops->vbus_session) + return -EOPNOTSUPP; + return gadget->ops->vbus_session (gadget, 1); +} + +/** + * usb_gadget_vbus_draw - constrain controller's VBUS power usage + * @gadget:The device whose VBUS usage is being described + * @mA:How much current to draw, in milliAmperes. This should be twice + * the value listed in the configuration descriptor bMaxPower field. + * + * This call is used by gadget drivers during SET_CONFIGURATION calls, + * reporting how much power the device may consume. For example, this + * could affect how quickly batteries are recharged. + * + * Returns zero on success, else negative errno. + */ +static inline int +usb_gadget_vbus_draw(struct usb_gadget *gadget, unsigned mA) +{ + if (!gadget->ops->vbus_draw) + return -EOPNOTSUPP; + return gadget->ops->vbus_draw (gadget, mA); +} + +/** + * usb_gadget_vbus_disconnect - notify controller about VBUS session end + * @gadget:the device whose VBUS supply is being described + * + * This call is used by a driver for an external transceiver (or GPIO) + * that detects a VBUS power session ending. Common responses include + * reversing everything done in usb_gadget_vbus_connect(). + * + * Returns zero on success, else negative errno. + */ +static inline int +usb_gadget_vbus_disconnect(struct usb_gadget *gadget) +{ + if (!gadget->ops->vbus_session) + return -EOPNOTSUPP; + return gadget->ops->vbus_session (gadget, 0); +} + +/** + * usb_gadget_connect - software-controlled connect to USB host + * @gadget:the peripheral being connected + * + * Enables the D+ (or potentially D-) pullup. The host will start + * enumerating this gadget when the pullup is active and a VBUS session + * is active (the link is powered). This pullup is always enabled unless + * usb_gadget_disconnect() has been used to disable it. + * + * Returns zero on success, else negative errno. + */ +static inline int +usb_gadget_connect (struct usb_gadget *gadget) +{ + if (!gadget->ops->pullup) + return -EOPNOTSUPP; + return gadget->ops->pullup (gadget, 1); +} + +/** + * usb_gadget_disconnect - software-controlled disconnect from USB host + * @gadget:the peripheral being disconnected + * + * Disables the D+ (or potentially D-) pullup, which the host may see + * as a disconnect (when a VBUS session is active). Not all systems + * support software pullup controls. + * + * This routine may be used during the gadget driver bind() call to prevent + * the peripheral from ever being visible to the USB host, unless later + * usb_gadget_connect() is called. For example, user mode components may + * need to be activated before the system can talk to hosts. + * + * Returns zero on success, else negative errno. + */ +static inline int +usb_gadget_disconnect (struct usb_gadget *gadget) +{ + if (!gadget->ops->pullup) + return -EOPNOTSUPP; + return gadget->ops->pullup (gadget, 0); +} + + + +/*-------------------------------------------------------------------------*/ + +/** + * struct usb_gadget_driver - driver for usb 'slave' devices + * @function: String describing the gadget's function + * @speed: Highest speed the driver handles. + * @bind: Invoked when the driver is bound to a gadget, usually + * after registering the driver. + * At that point, ep0 is fully initialized, and ep_list holds + * the currently-available endpoints. + * Called in a context that permits sleeping. + * @setup: Invoked for ep0 control requests that aren't handled by + * the hardware level driver. Most calls must be handled by + * the gadget driver, including descriptor and configuration + * management. The 16 bit members of the setup data are in + * USB byte order. Called in_interrupt; this may not sleep. Driver + * queues a response to ep0, or returns negative to stall. + * @disconnect: Invoked after all transfers have been stopped, + * when the host is disconnected. May be called in_interrupt; this + * may not sleep. Some devices can't detect disconnect, so this might + * not be called except as part of controller shutdown. + * @unbind: Invoked when the driver is unbound from a gadget, + * usually from rmmod (after a disconnect is reported). + * Called in a context that permits sleeping. + * @suspend: Invoked on USB suspend. May be called in_interrupt. + * @resume: Invoked on USB resume. May be called in_interrupt. + * @driver: Driver model state for this driver. + * + * Devices are disabled till a gadget driver successfully bind()s, which + * means the driver will handle setup() requests needed to enumerate (and + * meet "chapter 9" requirements) then do some useful work. + * + * If gadget->is_otg is true, the gadget driver must provide an OTG + * descriptor during enumeration, or else fail the bind() call. In such + * cases, no USB traffic may flow until both bind() returns without + * having called usb_gadget_disconnect(), and the USB host stack has + * initialized. + * + * Drivers use hardware-specific knowledge to configure the usb hardware. + * endpoint addressing is only one of several hardware characteristics that + * are in descriptors the ep0 implementation returns from setup() calls. + * + * Except for ep0 implementation, most driver code shouldn't need change to + * run on top of different usb controllers. It'll use endpoints set up by + * that ep0 implementation. + * + * The usb controller driver handles a few standard usb requests. Those + * include set_address, and feature flags for devices, interfaces, and + * endpoints (the get_status, set_feature, and clear_feature requests). + * + * Accordingly, the driver's setup() callback must always implement all + * get_descriptor requests, returning at least a device descriptor and + * a configuration descriptor. Drivers must make sure the endpoint + * descriptors match any hardware constraints. Some hardware also constrains + * other descriptors. (The pxa250 allows only configurations 1, 2, or 3). + * + * The driver's setup() callback must also implement set_configuration, + * and should also implement set_interface, get_configuration, and + * get_interface. Setting a configuration (or interface) is where + * endpoints should be activated or (config 0) shut down. + * + * (Note that only the default control endpoint is supported. Neither + * hosts nor devices generally support control traffic except to ep0.) + * + * Most devices will ignore USB suspend/resume operations, and so will + * not provide those callbacks. However, some may need to change modes + * when the host is not longer directing those activities. For example, + * local controls (buttons, dials, etc) may need to be re-enabled since + * the (remote) host can't do that any longer; or an error state might + * be cleared, to make the device behave identically whether or not + * power is maintained. + */ +struct usb_gadget_driver { + char *function; + enum usb_device_speed speed; + int (*bind)(struct usb_gadget *); + void (*unbind)(struct usb_gadget *); + int (*setup)(struct usb_gadget *, + const struct usb_ctrlrequest *); + void (*disconnect)(struct usb_gadget *); + void (*suspend)(struct usb_gadget *); + void (*resume)(struct usb_gadget *); + + // FIXME support safe rmmod + struct device_driver driver; +}; + + + +/*-------------------------------------------------------------------------*/ + +/* driver modules register and unregister, as usual. + * these calls must be made in a context that can sleep. + * + * these will usually be implemented directly by the hardware-dependent + * usb bus interface driver, which will only support a single driver. + */ + +/** + * usb_gadget_register_driver - register a gadget driver + * @driver:the driver being registered + * + * Call this in your gadget driver's module initialization function, + * to tell the underlying usb controller driver about your driver. + * The driver's bind() function will be called to bind it to a + * gadget before this registration call returns. It's expected that + * the bind() functions will be in init sections. + * This function must be called in a context that can sleep. + */ +int usb_gadget_register_driver (struct usb_gadget_driver *driver); + +/** + * usb_gadget_unregister_driver - unregister a gadget driver + * @driver:the driver being unregistered + * + * Call this in your gadget driver's module cleanup function, + * to tell the underlying usb controller that your driver is + * going away. If the controller is connected to a USB host, + * it will first disconnect(). The driver is also requested + * to unbind() and clean up any device state, before this procedure + * finally returns. It's expected that the unbind() functions + * will in in exit sections, so may not be linked in some kernels. + * This function must be called in a context that can sleep. + */ +int usb_gadget_unregister_driver (struct usb_gadget_driver *driver); + +/*-------------------------------------------------------------------------*/ + +/* utility to simplify dealing with string descriptors */ + +/** + * struct usb_string - wraps a C string and its USB id + * @id:the (nonzero) ID for this string + * @s:the string, in UTF-8 encoding + * + * If you're using usb_gadget_get_string(), use this to wrap a string + * together with its ID. + */ +struct usb_string { + u8 id; + const char *s; +}; + +/** + * struct usb_gadget_strings - a set of USB strings in a given language + * @language:identifies the strings' language (0x0409 for en-us) + * @strings:array of strings with their ids + * + * If you're using usb_gadget_get_string(), use this to wrap all the + * strings for a given language. + */ +struct usb_gadget_strings { + u16 language; /* 0x0409 for en-us */ + struct usb_string *strings; +}; + +/* put descriptor for string with that id into buf (buflen >= 256) */ +int usb_gadget_get_string (struct usb_gadget_strings *table, int id, u8 *buf); + +/*-------------------------------------------------------------------------*/ + +/* utility to simplify managing config descriptors */ + +/* write vector of descriptors into buffer */ +int usb_descriptor_fillbuf(void *, unsigned, + const struct usb_descriptor_header **); + +/* build config descriptor from single descriptor vector */ +int usb_gadget_config_buf(const struct usb_config_descriptor *config, + void *buf, unsigned buflen, const struct usb_descriptor_header **desc); + +/*-------------------------------------------------------------------------*/ + +/* utility wrapping a simple endpoint selection policy */ + +extern struct usb_ep *usb_ep_autoconfig (struct usb_gadget *, + struct usb_endpoint_descriptor *) __devinit; + +extern void usb_ep_autoconfig_reset (struct usb_gadget *) __devinit; + +#endif /* __KERNEL__ */ + +#endif /* __LINUX_USB_GADGET_H */ |