LXR qemu/hw/i2c.c

   1/*
   2 * QEMU I2C bus interface.
   3 *
   4 * Copyright (c) 2007 CodeSourcery.
   5 * Written by Paul Brook
   6 *
   7 * This code is licenced under the LGPL.
   8 */
   9
  10#include "i2c.h"
  11
  12struct i2c_bus
  13{
  14    BusState qbus;
  15    i2c_slave *current_dev;
  16    i2c_slave *dev;
  17    uint8_t saved_address;
  18};
  19
  20static struct BusInfo i2c_bus_info = {
  21    .name = "I2C",
  22    .size = sizeof(i2c_bus),
  23    .props = (Property[]) {
  24        DEFINE_PROP_UINT8("address", struct i2c_slave, address, 0),
  25        DEFINE_PROP_END_OF_LIST(),
  26    }
  27};
  28
  29static void i2c_bus_pre_save(void *opaque)
  30{
  31    i2c_bus *bus = opaque;
  32
  33    bus->saved_address = bus->current_dev ? bus->current_dev->address : -1;
  34}
  35
  36static int i2c_bus_post_load(void *opaque, int version_id)
  37{
  38    i2c_bus *bus = opaque;
  39
  40    /* The bus is loaded before attached devices, so load and save the
  41       current device id.  Devices will check themselves as loaded.  */
  42    bus->current_dev = NULL;
  43    return 0;
  44}
  45
  46static const VMStateDescription vmstate_i2c_bus = {
  47    .name = "i2c_bus",
  48    .version_id = 1,
  49    .minimum_version_id = 1,
  50    .minimum_version_id_old = 1,
  51    .pre_save = i2c_bus_pre_save,
  52    .post_load = i2c_bus_post_load,
  53    .fields      = (VMStateField []) {
  54        VMSTATE_UINT8(saved_address, i2c_bus),
  55        VMSTATE_END_OF_LIST()
  56    }
  57};
  58
  59/* Create a new I2C bus.  */
  60i2c_bus *i2c_init_bus(DeviceState *parent, const char *name)
  61{
  62    i2c_bus *bus;
  63
  64    bus = FROM_QBUS(i2c_bus, qbus_create(&i2c_bus_info, parent, name));
  65    vmstate_register(NULL, -1, &vmstate_i2c_bus, bus);
  66    return bus;
  67}
  68
  69void i2c_set_slave_address(i2c_slave *dev, uint8_t address)
  70{
  71    dev->address = address;
  72}
  73
  74/* Return nonzero if bus is busy.  */
  75int i2c_bus_busy(i2c_bus *bus)
  76{
  77    return bus->current_dev != NULL;
  78}
  79
  80/* Returns non-zero if the address is not valid.  */
  81/* TODO: Make this handle multiple masters.  */
  82int i2c_start_transfer(i2c_bus *bus, uint8_t address, int recv)
  83{
  84    DeviceState *qdev;
  85    i2c_slave *slave = NULL;
  86
  87    QLIST_FOREACH(qdev, &bus->qbus.children, sibling) {
  88        i2c_slave *candidate = I2C_SLAVE_FROM_QDEV(qdev);
  89        if (candidate->address == address) {
  90            slave = candidate;
  91            break;
  92        }
  93    }
  94
  95    if (!slave)
  96        return 1;
  97
  98    /* If the bus is already busy, assume this is a repeated
  99       start condition.  */
 100    bus->current_dev = slave;
 101    slave->info->event(slave, recv ? I2C_START_RECV : I2C_START_SEND);
 102    return 0;
 103}
 104
 105void i2c_end_transfer(i2c_bus *bus)
 106{
 107    i2c_slave *dev = bus->current_dev;
 108
 109    if (!dev)
 110        return;
 111
 112    dev->info->event(dev, I2C_FINISH);
 113
 114    bus->current_dev = NULL;
 115}
 116
 117int i2c_send(i2c_bus *bus, uint8_t data)
 118{
 119    i2c_slave *dev = bus->current_dev;
 120
 121    if (!dev)
 122        return -1;
 123
 124    return dev->info->send(dev, data);
 125}
 126
 127int i2c_recv(i2c_bus *bus)
 128{
 129    i2c_slave *dev = bus->current_dev;
 130
 131    if (!dev)
 132        return -1;
 133
 134    return dev->info->recv(dev);
 135}
 136
 137void i2c_nack(i2c_bus *bus)
 138{
 139    i2c_slave *dev = bus->current_dev;
 140
 141    if (!dev)
 142        return;
 143
 144    dev->info->event(dev, I2C_NACK);
 145}
 146
 147static int i2c_slave_post_load(void *opaque, int version_id)
 148{
 149    i2c_slave *dev = opaque;
 150    i2c_bus *bus;
 151    bus = FROM_QBUS(i2c_bus, qdev_get_parent_bus(&dev->qdev));
 152    if (bus->saved_address == dev->address) {
 153        bus->current_dev = dev;
 154    }
 155    return 0;
 156}
 157
 158const VMStateDescription vmstate_i2c_slave = {
 159    .name = "i2c_slave",
 160    .version_id = 1,
 161    .minimum_version_id = 1,
 162    .minimum_version_id_old = 1,
 163    .post_load = i2c_slave_post_load,
 164    .fields      = (VMStateField []) {
 165        VMSTATE_UINT8(address, i2c_slave),
 166        VMSTATE_END_OF_LIST()
 167    }
 168};
 169
 170static int i2c_slave_qdev_init(DeviceState *dev, DeviceInfo *base)
 171{
 172    I2CSlaveInfo *info = container_of(base, I2CSlaveInfo, qdev);
 173    i2c_slave *s = I2C_SLAVE_FROM_QDEV(dev);
 174
 175    s->info = info;
 176
 177    return info->init(s);
 178}
 179
 180void i2c_register_slave(I2CSlaveInfo *info)
 181{
 182    assert(info->qdev.size >= sizeof(i2c_slave));
 183    info->qdev.init = i2c_slave_qdev_init;
 184    info->qdev.bus_info = &i2c_bus_info;
 185    qdev_register(&info->qdev);
 186}
 187
 188DeviceState *i2c_create_slave(i2c_bus *bus, const char *name, uint8_t addr)
 189{
 190    DeviceState *dev;
 191
 192    dev = qdev_create(&bus->qbus, name);
 193    qdev_prop_set_uint8(dev, "address", addr);
 194    qdev_init_nofail(dev);
 195    return dev;
 196}
 197