path: root/include/linux/usb/gadget.h

// SPDX-License-Identifier: GPL-2.0
/*
 * <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
 * talk to many USB gadgets, but the gadgets are only able to communicate
 * to one host.
 *
 *
 * (C) Copyright 2002-2004 by David Brownell
 * All Rights Reserved.
 */

#ifndef __LINUX_USB_GADGET_H
#define __LINUX_USB_GADGET_H

#include <linux/configfs.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/scatterlist.h>
#include <linux/types.h>
#include <linux/workqueue.h>
#include <linux/usb/ch9.h>

#define UDC_TRACE_STR_MAX	512

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.
 * @sg: a scatterlist for SG-capable controllers.
 * @num_sgs: number of SG entries
 * @num_mapped_sgs: number of SG entries mapped to DMA (internal)
 * @length: Length of that data
 * @stream_id: The stream id, when USB3.0 bulk streams are being used
 * @is_last: Indicates if this is the last request of a stream_id before
 *	switching to a different stream (required for DWC3 controllers).
 * @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).
 * @dma_mapped: Indicates if request has been mapped to DMA (internal)
 * @sg_was_mapped: Set if the scatterlist has been mapped before the request
 * @complete: Function called when request completes, so this request and
 *	its buffer may be re-used.  The function will always be called with
 *	interrupts disabled, and it must not sleep.
 *	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.
 * @frame_number: Reports the interval number in (micro)frame in which the
 *	isochronous transfer was transmitted or received.
 * @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 analogous 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;

	struct scatterlist	*sg;
	unsigned		num_sgs;
	unsigned		num_mapped_sgs;

	unsigned		stream_id:16;
	unsigned		is_last:1;
	unsigned		no_interrupt:1;
	unsigned		zero:1;
	unsigned		short_not_ok:1;
	unsigned		dma_mapped:1;
	unsigned		sg_was_mapped:1;

	void			(*complete)(struct usb_ep *ep,
					struct usb_request *req);
	void			*context;
	struct list_head	list;

	unsigned		frame_number;		/* ISO ONLY */

	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);
	void (*dispose) (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 (*set_wedge) (struct usb_ep *ep);

	int (*fifo_status) (struct usb_ep *ep);
	void (*fifo_flush) (struct usb_ep *ep);
};

/**
 * struct usb_ep_caps - endpoint capabilities description
 * @type_control:Endpoint supports control type (reserved for ep0).
 * @type_iso:Endpoint supports isochronous transfers.
 * @type_bulk:Endpoint supports bulk transfers.
 * @type_int:Endpoint supports interrupt transfers.
 * @dir_in:Endpoint supports IN direction.
 * @dir_out:Endpoint supports OUT direction.
 */
struct usb_ep_caps {
	unsigned type_control:1;
	unsigned type_iso:1;
	unsigned type_bulk:1;
	unsigned type_int:1;
	unsigned dir_in:1;
	unsigned dir_out:1;
};

#define USB_EP_CAPS_TYPE_CONTROL     0x01
#define USB_EP_CAPS_TYPE_ISO         0x02
#define USB_EP_CAPS_TYPE_BULK        0x04
#define USB_EP_CAPS_TYPE_INT         0x08
#define USB_EP_CAPS_TYPE_ALL \
	(USB_EP_CAPS_TYPE_ISO | USB_EP_CAPS_TYPE_BULK | USB_EP_CAPS_TYPE_INT)
#define USB_EP_CAPS_DIR_IN           0x01
#define USB_EP_CAPS_DIR_OUT          0x02
#define USB_EP_CAPS_DIR_ALL  (USB_EP_CAPS_DIR_IN | USB_EP_CAPS_DIR_OUT)

#define USB_EP_CAPS(_type, _dir) \
	{ \
		.type_control = !!(_type & USB_EP_CAPS_TYPE_CONTROL), \
		.type_iso = !!(_type & USB_EP_CAPS_TYPE_ISO), \
		.type_bulk = !!(_type & USB_EP_CAPS_TYPE_BULK), \
		.type_int = !!(_type & USB_EP_CAPS_TYPE_INT), \
		.dir_in = !!(_dir & USB_EP_CAPS_DIR_IN), \
		.dir_out = !!(_dir & USB_EP_CAPS_DIR_OUT), \
	}

/**
 * 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
 * @caps:The structure describing types and directions supported by endpoint.
 * @enabled: The current endpoint enabled/disabled state.
 * @claimed: True if this endpoint is claimed by a function.
 * @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.
 * @maxpacket_limit:The maximum packet size value which can be handled by this
 *	endpoint. It's set once by UDC driver when endpoint is initialized, and
 *	should not be changed. Should not be confused with maxpacket.
 * @max_streams: The maximum number of streams supported
 *	by this EP (0 - 16, actual number is 2^n)
 * @mult: multiplier, 'mult' value for SS Isoc EPs
 * @maxburst: the maximum number of bursts supported by this EP (for usb3)
 * @driver_data:for use by the gadget driver.
 * @address: used to identify the endpoint when finding descriptor that
 *	matches connection speed
 * @desc: endpoint descriptor.  This pointer is set before the endpoint is
 *	enabled and remains valid until the endpoint is disabled.
 * @comp_desc: In case of SuperSpeed support, this is the endpoint companion
 *	descriptor that is used to configure the endpoint
 *
 * 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;
	const struct usb_endpoint_descriptor	*desc;
	const struct usb_ss_ep_comp_descriptor	*comp_desc;
	struct list_head	ep_list;
	struct usb_ep_caps	caps;
	bool			claimed;
	bool			enabled;
	unsigned		mult:2;
	unsigned		maxburst:5;
	u8			address;
	u16			maxpacket;
	u16			maxpacket_limit;
	u16			max_streams;
};

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

#if IS_ENABLED(CONFIG_USB_GADGET)
void usb_ep_set_maxpacket_limit(struct usb_ep *ep, unsigned maxpacket_limit);
int usb_ep_enable(struct usb_ep *ep);
int usb_ep_disable(struct usb_ep *ep);
struct usb_request *usb_ep_alloc_request(struct usb_ep *ep, gfp_t gfp_flags);
void usb_ep_free_request(struct usb_ep *ep, struct usb_request *req);
int usb_ep_queue(struct usb_ep *ep, struct usb_request *req, gfp_t gfp_flags