linux/include/media/cec-pin.h

/*
 * cec-pin.h - low-level CEC pin control
 *
 * Copyright 2017 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
 *
 * This program is free software; you may redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#ifndef LINUX_CEC_PIN_H
#define LINUX_CEC_PIN_H

#include <linux/types.h>
#include <linux/atomic.h>
#include <media/cec.h>

enum cec_pin_state {
	/* CEC is off */
	CEC_ST_OFF,
	/* CEC is idle, waiting for Rx or Tx */
	CEC_ST_IDLE,

	/* Tx states */

	/* Pending Tx, waiting for Signal Free Time to expire */
	CEC_ST_TX_WAIT,
	/* Low-drive was detected, wait for bus to go high */
	CEC_ST_TX_WAIT_FOR_HIGH,
	/* Drive CEC low for the start bit */
	CEC_ST_TX_START_BIT_LOW,
	/* Drive CEC high for the start bit */
	CEC_ST_TX_START_BIT_HIGH,
	/* Drive CEC low for the 0 bit */
	CEC_ST_TX_DATA_BIT_0_LOW,
	/* Drive CEC high for the 0 bit */
	CEC_ST_TX_DATA_BIT_0_HIGH,
	/* Drive CEC low for the 1 bit */
	CEC_ST_TX_DATA_BIT_1_LOW,
	/* Drive CEC high for the 1 bit */
	CEC_ST_TX_DATA_BIT_1_HIGH,
	/*
	 * Wait for start of sample time to check for Ack bit or first
	 * four initiator bits to check for Arbitration Lost.
	 */
	CEC_ST_TX_DATA_BIT_1_HIGH_PRE_SAMPLE,
	/* Wait for end of bit period after sampling */
	CEC_ST_TX_DATA_BIT_1_HIGH_POST_SAMPLE,

	/* Rx states */

	/* Start bit low detected */
	CEC_ST_RX_START_BIT_LOW,
	/* Start bit high detected */
	CEC_ST_RX_START_BIT_HIGH,
	/* Wait for bit sample time */
	CEC_ST_RX_DATA_SAMPLE,
	/* Wait for earliest end of bit period after sampling */
	CEC_ST_RX_DATA_POST_SAMPLE,
	/* Wait for CEC to go high (i.e. end of bit period */
	CEC_ST_RX_DATA_HIGH,
	/* Drive CEC low to send 0 Ack bit */
	CEC_ST_RX_ACK_LOW,
	/* End of 0 Ack time, wait for earliest end of bit period */
	CEC_ST_RX_ACK_LOW_POST,
	/* Wait for CEC to go high (i.e. end of bit period */
	CEC_ST_RX_ACK_HIGH_POST,
	/* Wait for earliest end of bit period and end of message */
	CEC_ST_RX_ACK_FINISH,

	/* Start low drive */
	CEC_ST_LOW_DRIVE,
	/* Monitor pin using interrupts */
	CEC_ST_RX_IRQ,

	/* Total number of pin states */
	CEC_PIN_STATES
};

/**
 * struct cec_pin_ops - low-level CEC pin operations
 * @read:	read the CEC pin. Return true if high, false if low.
 * @low:	drive the CEC pin low.
 * @high:	stop driving the CEC pin. The pull-up will drive the pin
 *		high, unless someone else is driving the pin low.
 * @enable_irq:	optional, enable the interrupt to detect pin voltage changes.
 * @disable_irq: optional, disable the interrupt.
 * @free:	optional. Free any allocated resources. Called when the
 *		adapter is deleted.
 * @status:	optional, log status information.
 *
 * These operations are used by the cec pin framework to manipulate
 * the CEC pin.
 */
struct cec_pin_ops {
	bool (*read)(struct cec_adapter *adap);
	void (*low)(struct cec_adapter *adap);
	void (*high)(struct cec_adapter *adap);
	bool (*enable_irq)(struct cec_adapter *adap);
	void (*disable_irq)(struct cec_adapter *adap);
	void (*free)(struct cec_adapter *adap);
	void (*status)(struct cec_adapter *adap, struct seq_file *file);
};

#define CEC_NUM_PIN_EVENTS 128

#define CEC_PIN_IRQ_UNCHANGED	0
#define CEC_PIN_IRQ_DISABLE	1
#define CEC_PIN_IRQ_ENABLE	2

struct cec_pin {
	struct cec_adapter		*adap;
	const struct cec_pin_ops	*ops;
	struct task_struct		*kthread;
	wait_queue_head_t		kthread_waitq;
	struct hrtimer			timer;
	ktime_t				ts;
	unsigned int			wait_usecs;
	u16				la_mask;
	bool				enabled;
	bool				monitor_all;
	bool				rx_eom;
	bool				enable_irq_failed;
	enum cec_pin_state		state;
	struct cec_msg			tx_msg;
	u32				tx_bit;
	bool				tx_nacked;
	u32				tx_signal_free_time;
	struct cec_msg			rx_msg;
	u32				rx_bit;

	struct cec_msg			work_rx_msg;
	u8				work_tx_status;
	ktime_t				work_tx_ts;
	atomic_t			work_irq_change;
	atomic_t			work_pin_events;
	unsigned int			work_pin_events_wr;
	unsigned int			work_pin_events_rd;
	ktime_t				work_pin_ts[CEC_NUM_PIN_EVENTS];
	bool				work_pin_is_high[CEC_NUM_PIN_EVENTS];
	ktime_t				timer_ts;
	u32				timer_cnt;
	u32				timer_100ms_overruns;
	u32				timer_300ms_overruns;
	u32				timer_max_overrun;
	u32				timer_sum_overrun;
};

/**
 * cec_pin_changed() - update pin state from interrupt
 *
 * @adap:	pointer to the cec adapter
 * @value:	when true the pin is high, otherwise it is low
 *
 * If changes of the CEC voltage are detected via an interrupt, then
 * cec_pin_changed is called from the interrupt with the new value.
 */
void cec_pin_changed(struct cec_adapter *adap, bool value);

/**
 * cec_pin_allocate_adapter() - allocate a pin-based cec adapter
 *
 * @pin_ops:	low-level pin operations
 * @priv:	will be stored in adap->priv and can be used by the adapter ops.
 *		Use cec_get_drvdata(adap) to get the priv pointer.
 * @name:	the name of the CEC adapter. Note: this name will be copied.
 * @caps:	capabilities of the CEC adapter. This will be ORed with
 *		CEC_CAP_MONITOR_ALL and CEC_CAP_MONITOR_PIN.
 *
 * Allocate a cec adapter using the cec pin framework.
 *
 * Return: a pointer to the cec adapter or an error pointer
 */
struct cec_adapter *cec_pin_allocate_adapter(const struct cec_pin_ops *pin_ops,
					void *priv, const char *name, u32 caps);

#endif