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/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef INCLUDE_OUT_STREAM_H
#define INCLUDE_OUT_STREAM_H
#include <stddef.h>
#include <stdint.h>
struct out_stream;
/*
* An out_stream is a generic interface providing operations that can be used
* to send a character stream over a USB endpoint, UART, I2C host interface, and
* more. Each realization of an out_stream provides a constant instance of
* the out_stream_ops structure that is used to operate on that realizations
* out_streams. For example, the UART driver could provide one out_stream_ops
* structure and four UART configs. Each UART config uses the same
* out_stream_ops structure.
*/
struct out_stream_ops {
/*
* Write at most count characters from buffer into the output stream.
* Return the number of characters actually written.
*/
size_t (*write)(struct out_stream const *stream,
uint8_t const *buffer,
size_t count);
/*
* Flush all outgoing data. This works if we are in an interrupt
* context, or normal context. The call blocks until the output
* stream is empty.
*/
void (*flush)(struct out_stream const *stream);
};
/*
* The out_stream structure is embedded in the device configuration structure
* that wishes to publish an out_stream capable interface. Uses of that device
* can pass a pointer to the embedded out_stream around and use it like any
* other out_stream.
*/
struct out_stream {
/*
* Ready will be called by the stream every time characters are removed
* from the stream. This may be called from an interrupt context
* so work done by the ready callback should be minimal. Likely this
* callback will be used to call task_wake, or some similar signaling
* mechanism.
*
* This callback is part of the user configuration of a stream, and not
* a stream manipulation function (in_stream_ops). That means that
* each stream can be configured with its own ready callback.
*
* If no callback functionality is required ready can be specified as
* NULL.
*/
void (*ready)(struct out_stream const *stream);
struct out_stream_ops const *ops;
};
/*
* Helper functions that call the associated stream operation and pass it the
* given stream. These help prevent mistakes where one stream is passed to
* another stream's functions.
*/
size_t out_stream_write(struct out_stream const *stream,
uint8_t const *buffer,
size_t count);
void out_stream_flush(struct out_stream const *stream);
void out_stream_ready(struct out_stream const *stream);
#endif /* INCLUDE_OUT_STREAM_H */
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