linux/drivers/media/test-drivers/vivid/vivid-cec.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * vivid-cec.c - A Virtual Video Test Driver, cec emulation
 *
 * Copyright 2016 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
 */

#include <linux/delay.h>
#include <media/cec.h>

#include "vivid-core.h"
#include "vivid-cec.h"

#define CEC_START_BIT_US …
#define CEC_DATA_BIT_US …
#define CEC_MARGIN_US …

struct xfer_on_bus { … };

static bool find_dest_adap(struct vivid_dev *dev,
			   struct cec_adapter *adap, u8 dest)
{ … }

static bool xfer_ready(struct vivid_dev *dev)
{ … }

/*
 * If an adapter tries to send successive messages, it must wait for the
 * longest signal-free time between its transmissions. But, if another
 * adapter sends a message in the interim, then the wait can be reduced
 * because the messages are no longer successive. Make these adjustments
 * if necessary. Should be called holding cec_xfers_slock.
 */
static void adjust_sfts(struct vivid_dev *dev)
{ … }

/*
 * The main emulation of the bus on which CEC adapters attempt to send
 * messages to each other. The bus keeps track of how long it has been
 * signal-free and accepts a pending transmission only if the state of
 * the bus matches the transmission's signal-free requirements. It calls
 * cec_transmit_attempt_done() for all transmits that enter the bus and
 * cec_received_msg() for successful transmits.
 */
int vivid_cec_bus_thread(void *_dev)
{ … }

static int vivid_cec_adap_enable(struct cec_adapter *adap, bool enable)
{ … }

static int vivid_cec_adap_log_addr(struct cec_adapter *adap, u8 log_addr)
{ … }

static int vivid_cec_adap_transmit(struct cec_adapter *adap, u8 attempts,
				   u32 signal_free_time, struct cec_msg *msg)
{ … }

static int vivid_received(struct cec_adapter *adap, struct cec_msg *msg)
{ … }

static const struct cec_adap_ops vivid_cec_adap_ops = …;

struct cec_adapter *vivid_cec_alloc_adap(struct vivid_dev *dev,
					 unsigned int idx,
					 bool is_source)
{ … }