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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
+ */
+
+#include "dev/i2c/bus.hh"
+
+#include "debug/Checkpoint.hh"
+#include "dev/i2c/device.hh"
+#include "mem/packet_access.hh"
+
+// clang complains about std::set being overloaded with Packet::set if
+// we open up the entire namespace std
+using std::vector;
+using std::map;
+
+/**
+ * 4KB - see e.g.
+ * http://infocenter.arm.com/help/topic/com.arm.doc.dui0440b/Bbajihec.html
+ */
+I2CBus::I2CBus(const I2CBusParams *p)
+ : BasicPioDevice(p, 0xfff), scl(1), sda(1), state(IDLE), currBit(7),
+ i2cAddr(0x00), message(0x00)
+{
+ vector<I2CDevice*> devs = p->devices;
+
+ for (auto d : p->devices) {
+ devices[d->i2cAddr()] = d;
+ }
+}
+
+/**
+ * Reads will always be to SB_CONTROLS. The kernel wants to know the state
+ * of sda and scl.
+ */
+Tick
+I2CBus::read(PacketPtr pkt)
+{
+ assert(pkt->getAddr() == pioAddr + SB_CONTROLS);
+
+ pkt->set<uint8_t>((sda << 1) | scl);
+ pkt->makeAtomicResponse();
+ return pioDelay;
+}
+
+/**
+ * The default i2c bus driver used by the realview pbx board writes to
+ * this device one bit at a time. To facilitate making new i2c devices,
+ * i2cBus::write takes care of the low-level details of the i2c protocol.
+ * See the I2C Specification [1] for a detailed description of the
+ * protocol.
+ *
+ * [1] - http://www.nxp.com/documents/user_manual/UM10204.pdf
+ */
+Tick
+I2CBus::write(PacketPtr pkt)
+{
+ assert(pkt->getAddr() == pioAddr + SB_CONTROLS ||
+ pkt->getAddr() == pioAddr + SB_CONTROLC);
+
+ updateSignals(pkt);
+
+ // Check if the bus master is starting a new transmission.
+ if (isStart(pkt)) {
+ state = RECEIVING_ADDR;
+ message = 0x00;
+ currBit = 7;
+ /* Most i2c devices expect something special (e.g., command,
+ * register address) in the first byte they receive so they
+ * must be notified somehow that this is a new transmission.
+ */
+ for (auto& d : devices) {
+ d.second->i2cStart();
+ }
+ return pioDelay;
+ }
+
+ // Check if the bus master is ending a transmission.
+ if (isEnd(pkt)) {
+ state = IDLE;
+ return pioDelay;
+ }
+
+ // Only change state when the clock is transitioning from low to high.
+ // This may not perfectly mimic physical i2c devices but the important
+ // part is to only do the following once per clock cycle.
+ if (isClockSet(pkt)) {
+ switch (state) {
+ case RECEIVING_ADDR:
+ if (currBit >= 0) {
+ message |= sda << currBit;
+ currBit--;
+ } else {
+ i2cAddr = message >> 1;
+ assert(devices.find(i2cAddr) != devices.end());
+ if (message & 0x01) {
+ state = SENDING_DATA;
+ message = devices[i2cAddr]->read();
+ } else {
+ state = RECEIVING_DATA;
+ message = 0x00;
+ }
+ currBit = 7;
+ sda = 0; /* Ack */
+ }
+ break;
+ case RECEIVING_DATA:
+ if (currBit >= 0) {
+ message |= sda << currBit;
+ currBit--;
+ } else {
+ devices[i2cAddr]->write(message);
+ message = 0x00;
+ currBit = 7;
+ sda = 0; /* Ack */
+ }
+ break;
+ case SENDING_DATA:
+ if (currBit >= 0) {
+ sda = (message >> currBit) & 0x01;
+ currBit--;
+ } else {
+ if (!sda) /* Check for ack from the bus master. */
+ message = devices[i2cAddr]->read();
+ currBit = 7;
+ }
+ break;
+ case IDLE:
+ default:
+ panic("Invalid state on posedge of clock in I2CBus::write.\n");
+ break;
+ }
+ }
+
+ return pioDelay;
+}
+
+void
+I2CBus::updateSignals(PacketPtr pkt)
+{
+ uint8_t msg = pkt->get<uint8_t>();
+ Addr daddr = pkt->getAddr() - pioAddr;
+
+ switch (daddr) {
+ case SB_CONTROLS:
+ scl = (msg & 1) ? 1 : scl;
+ sda = (msg & 2) ? 1 : sda;
+ break;
+ case SB_CONTROLC:
+ scl = (msg & 1) ? 0 : scl;
+ sda = (msg & 2) ? 0 : sda;
+ break;
+ default:
+ break;
+ }
+}
+
+bool
+I2CBus::isClockSet(PacketPtr pkt) const
+{
+ uint8_t msg = pkt->get<uint8_t>();
+ Addr daddr = pkt->getAddr() - pioAddr;
+ return daddr == SB_CONTROLS && (msg & 1);
+}
+
+bool
+I2CBus::isStart(PacketPtr pkt) const
+{
+ uint8_t msg = pkt->get<uint8_t>();
+ Addr daddr = pkt->getAddr() - pioAddr;
+ return scl && (msg & 2) && daddr == SB_CONTROLC;
+}
+
+bool
+I2CBus::isEnd(PacketPtr pkt) const
+{
+ uint8_t msg = pkt->get<uint8_t>();
+ Addr daddr = pkt->getAddr() - pioAddr;
+ return scl && (msg & 2) && daddr == SB_CONTROLS;
+}
+void
+I2CBus::serialize(CheckpointOut &cp) const
+{
+ DPRINTF(Checkpoint, "Serializing I2C bus.\n");
+ SERIALIZE_SCALAR(scl);
+ SERIALIZE_SCALAR(sda);
+ SERIALIZE_ENUM(state);
+ SERIALIZE_SCALAR(currBit);
+ SERIALIZE_SCALAR(i2cAddr);
+ SERIALIZE_SCALAR(message);
+}
+
+void
+I2CBus::unserialize(CheckpointIn &cp)
+{
+ DPRINTF(Checkpoint, "Unserializing I2C bus.\n");
+ UNSERIALIZE_SCALAR(scl);
+ UNSERIALIZE_SCALAR(sda);
+ UNSERIALIZE_ENUM(state);
+ UNSERIALIZE_SCALAR(currBit);
+ UNSERIALIZE_SCALAR(i2cAddr);
+ UNSERIALIZE_SCALAR(message);
+}
+
+I2CBus*
+I2CBusParams::create()
+{
+ return new I2CBus(this);
+}
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