dev: Move i2c functionality to src/dev/i2c/

--HG--
rename : src/dev/I2C.py => src/dev/i2c/I2C.py
rename : src/dev/i2cbus.cc => src/dev/i2c/bus.cc
rename : src/dev/i2cbus.hh => src/dev/i2c/bus.hh
rename : src/dev/i2cdev.hh => src/dev/i2c/device.hh

1 files changed, 243 insertions, 0 deletions

diff --git a/src/dev/i2c/bus.cc b/src/dev/i2c/bus.cc
new file mode 100644
index 000000000..af5d6c825
--- /dev/null
+++ b/src/dev/i2c/bus.cc
@@ -0,0 +1,243 @@
+/*
+ * 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);
+}