154 lines
4.7 KiB
C++
154 lines
4.7 KiB
C++
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/*
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* Copyright (c) 2012 ARM Limited
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* All rights reserved
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*
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* The license below extends only to copyright in the software and shall
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* not be construed as granting a license to any other intellectual
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* property including but not limited to intellectual property relating
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* to a hardware implementation of the functionality of the software
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* licensed hereunder. You may use the software subject to the license
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* terms below provided that you ensure that this notice is replicated
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* unmodified and in its entirety in all distributions of the software,
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* modified or unmodified, in source code or in binary form.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Peter Enns
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*/
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/** @file
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* Implementiation of an i2c bus
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*/
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#ifndef __DEV_I2CBUS__
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#define __DEV_I2CBUS__
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#include <map>
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#include "dev/i2cdev.hh"
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#include "dev/io_device.hh"
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#include "params/I2CBus.hh"
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class I2CBus : public BasicPioDevice
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{
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protected:
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enum I2CState {
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IDLE,
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RECEIVING_ADDR,
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RECEIVING_DATA,
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SENDING_DATA,
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};
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/**
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* Read [and Set] serial control bits:
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* Bit [0] is SCL
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* Bit [1] is SDA
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*
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* http://infocenter.arm.com/help/topic/com.arm.doc.dui0440b/Bbajdjeg.html
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*/
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static const int SB_CONTROLS = 0x0;
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/** Clear control bits. Analogous to SB_CONTROLS */
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static const int SB_CONTROLC = 0x4;
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/** I2C clock wire (0, 1). */
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uint8_t scl;
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/** I2C data wire (0, 1) */
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uint8_t sda;
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/**
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* State used by I2CBus::write to determine what stage of an i2c
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* transmission it is currently in.
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*/
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enum I2CState state;
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/**
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* Order of the bit of the current message that is being sent or
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* received (0 - 7).
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*/
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int currBit;
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/**
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* Key used to access a device in the slave devices map. This
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* is the same address that is specified in kernel board
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* initialization code (e.g., arch/arm/mach-realview/core.c).
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*/
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uint8_t i2cAddr;
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/** 8-bit buffer used to send and receive messages bit by bit. */
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uint8_t message;
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/**
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* All the slave i2c devices that are connected to this
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* bus. Each device has an address that points to the actual
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* device.
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*/
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std::map<uint8_t, I2CDevice*> devices;
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/**
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* Update data (sda) and clock (scl) to match any transitions
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* specified by pkt.
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*
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* @param pkt memory request packet
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*/
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void updateSignals(PacketPtr pkt);
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/**
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* Clock set check
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*
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* @param pkt memory request packet
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* @return true if pkt indicates that scl transition from 0 to 1
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*/
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bool isClockSet(PacketPtr pkt) const;
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/**
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* i2c start signal check
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*
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* @param pkt memory request packet
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* @return true if pkt indicates a new transmission
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*/
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bool isStart(PacketPtr pkt) const;
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/**
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* i2c end signal check
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*
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* @param pkt memory request packet
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* @return true if pkt indicates stopping the current transmission
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*/
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bool isEnd(PacketPtr pkt) const;
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public:
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I2CBus(const I2CBusParams* p);
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virtual Tick read(PacketPtr pkt);
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virtual Tick write(PacketPtr pkt);
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virtual void serialize(std::ostream& os);
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virtual void unserialize(Checkpoint* cp, const std::string& section);
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};
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#endif //__DEV_I2CBUS
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