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/*
* Copyright (c) 2012 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
* not be construed as granting a license to any other intellectual
* property including but not limited to intellectual property relating
* to a hardware implementation of the functionality of the software
* licensed hereunder. You may use the software subject to the license
* terms below provided that you ensure that this notice is replicated
* unmodified and in its entirety in all distributions of the software,
* modified or unmodified, in source code or in binary form.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Authors: Peter Enns
*/
/** @file
* Implementiation of an i2c bus
*/
#ifndef __DEV_I2C_BUS_HH__
#define __DEV_I2C_BUS_HH__
#include <map>
#include "dev/io_device.hh"
#include "params/I2CBus.hh"
class I2CDevice;
class I2CBus : public BasicPioDevice
{
protected:
enum I2CState {
IDLE,
RECEIVING_ADDR,
RECEIVING_DATA,
SENDING_DATA,
};
/**
* Read [and Set] serial control bits:
* Bit [0] is SCL
* Bit [1] is SDA
*
* http://infocenter.arm.com/help/topic/com.arm.doc.dui0440b/Bbajdjeg.html
*/
static const int SB_CONTROLS = 0x0;
/** Clear control bits. Analogous to SB_CONTROLS */
static const int SB_CONTROLC = 0x4;
/** I2C clock wire (0, 1). */
uint8_t scl;
/** I2C data wire (0, 1) */
uint8_t sda;
/**
* State used by I2CBus::write to determine what stage of an i2c
* transmission it is currently in.
*/
enum I2CState state;
/**
* Order of the bit of the current message that is being sent or
* received (0 - 7).
*/
int currBit;
/**
* Key used to access a device in the slave devices map. This
* is the same address that is specified in kernel board
* initialization code (e.g., arch/arm/mach-realview/core.c).
*/
uint8_t i2cAddr;
/** 8-bit buffer used to send and receive messages bit by bit. */
uint8_t message;
/**
* All the slave i2c devices that are connected to this
* bus. Each device has an address that points to the actual
* device.
*/
std::map<uint8_t, I2CDevice*> devices;
/**
* Update data (sda) and clock (scl) to match any transitions
* specified by pkt.
*
* @param pkt memory request packet
*/
void updateSignals(PacketPtr pkt);
/**
* Clock set check
*
* @param pkt memory request packet
* @return true if pkt indicates that scl transition from 0 to 1
*/
bool isClockSet(PacketPtr pkt) const;
/**
* i2c start signal check
*
* @param pkt memory request packet
* @return true if pkt indicates a new transmission
*/
bool isStart(PacketPtr pkt) const;
/**
* i2c end signal check
*
* @param pkt memory request packet
* @return true if pkt indicates stopping the current transmission
*/
bool isEnd(PacketPtr pkt) const;
public:
I2CBus(const I2CBusParams* p);
Tick read(PacketPtr pkt) override;
Tick write(PacketPtr pkt) override;
void serialize(CheckpointOut &cp) const override;
void unserialize(CheckpointIn &cp) override;
};
#endif // __DEV_I2C_BUS_HH__
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