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 licensed under the LGPL.
   8  */
   9
  10 #include "i2c.h"
  11
  12 struct i2c_bus
  13 {
  14     BusState qbus;
  15     I2CSlave *current_dev;
  16     I2CSlave *dev;
  17     uint8_t saved_address;
  18 };
  19
  20 static Property i2c_props[] = {
  21     DEFINE_PROP_UINT8("address", struct I2CSlave, address, 0),
  22     DEFINE_PROP_END_OF_LIST(),
  23 };
  24
  25 #define TYPE_I2C_BUS "i2c-bus"
  26 #define I2C_BUS(obj) OBJECT_CHECK(i2c_bus, (obj), TYPE_I2C_BUS)
  27
  28 static const TypeInfo i2c_bus_info = {
  29     .name = TYPE_I2C_BUS,
  30     .parent = TYPE_BUS,
  31     .instance_size = sizeof(i2c_bus),
  32 };
  33
  34 static void i2c_bus_pre_save(void *opaque)
  35 {
  36     i2c_bus *bus = opaque;
  37
  38     bus->saved_address = bus->current_dev ? bus->current_dev->address : -1;
  39 }
  40
  41 static int i2c_bus_post_load(void *opaque, int version_id)
  42 {
  43     i2c_bus *bus = opaque;
  44
  45     /* The bus is loaded before attached devices, so load and save the
  46        current device id.  Devices will check themselves as loaded.  */
  47     bus->current_dev = NULL;
  48     return 0;
  49 }
  50
  51 static const VMStateDescription vmstate_i2c_bus = {
  52     .name = "i2c_bus",
  53     .version_id = 1,
  54     .minimum_version_id = 1,
  55     .minimum_version_id_old = 1,
  56     .pre_save = i2c_bus_pre_save,
  57     .post_load = i2c_bus_post_load,
  58     .fields      = (VMStateField []) {
  59         VMSTATE_UINT8(saved_address, i2c_bus),
  60         VMSTATE_END_OF_LIST()
  61     }
  62 };
  63
  64 /* Create a new I2C bus.  */
  65 i2c_bus *i2c_init_bus(DeviceState *parent, const char *name)
  66 {
  67     i2c_bus *bus;
  68
  69     bus = FROM_QBUS(i2c_bus, qbus_create(TYPE_I2C_BUS, parent, name));
  70     vmstate_register(NULL, -1, &vmstate_i2c_bus, bus);
  71     return bus;
  72 }
  73
  74 void i2c_set_slave_address(I2CSlave *dev, uint8_t address)
  75 {
  76     dev->address = address;
  77 }
  78
  79 /* Return nonzero if bus is busy.  */
  80 int i2c_bus_busy(i2c_bus *bus)
  81 {
  82     return bus->current_dev != NULL;
  83 }
  84
  85 /* Returns non-zero if the address is not valid.  */
  86 /* TODO: Make this handle multiple masters.  */
  87 int i2c_start_transfer(i2c_bus *bus, uint8_t address, int recv)
  88 {
  89     BusChild *kid;
  90     I2CSlave *slave = NULL;
  91     I2CSlaveClass *sc;
  92
  93     QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
  94         DeviceState *qdev = kid->child;
  95         I2CSlave *candidate = I2C_SLAVE_FROM_QDEV(qdev);
  96         if (candidate->address == address) {
  97             slave = candidate;
  98             break;
  99         }
 100     }
 101
 102     if (!slave) {
 103         return 1;
 104     }
 105
 106     sc = I2C_SLAVE_GET_CLASS(slave);
 107     /* If the bus is already busy, assume this is a repeated
 108        start condition.  */
 109     bus->current_dev = slave;
 110     if (sc->event) {
 111         sc->event(slave, recv ? I2C_START_RECV : I2C_START_SEND);
 112     }
 113     return 0;
 114 }
 115
 116 void i2c_end_transfer(i2c_bus *bus)
 117 {
 118     I2CSlave *dev = bus->current_dev;
 119     I2CSlaveClass *sc;
 120
 121     if (!dev) {
 122         return;
 123     }
 124
 125     sc = I2C_SLAVE_GET_CLASS(dev);
 126     if (sc->event) {
 127         sc->event(dev, I2C_FINISH);
 128     }
 129
 130     bus->current_dev = NULL;
 131 }
 132
 133 int i2c_send(i2c_bus *bus, uint8_t data)
 134 {
 135     I2CSlave *dev = bus->current_dev;
 136     I2CSlaveClass *sc;
 137
 138     if (!dev) {
 139         return -1;
 140     }
 141
 142     sc = I2C_SLAVE_GET_CLASS(dev);
 143     if (sc->send) {
 144         return sc->send(dev, data);
 145     }
 146
 147     return -1;
 148 }
 149
 150 int i2c_recv(i2c_bus *bus)
 151 {
 152     I2CSlave *dev = bus->current_dev;
 153     I2CSlaveClass *sc;
 154
 155     if (!dev) {
 156         return -1;
 157     }
 158
 159     sc = I2C_SLAVE_GET_CLASS(dev);
 160     if (sc->recv) {
 161         return sc->recv(dev);
 162     }
 163
 164     return -1;
 165 }
 166
 167 void i2c_nack(i2c_bus *bus)
 168 {
 169     I2CSlave *dev = bus->current_dev;
 170     I2CSlaveClass *sc;
 171
 172     if (!dev) {
 173         return;
 174     }
 175
 176     sc = I2C_SLAVE_GET_CLASS(dev);
 177     if (sc->event) {
 178         sc->event(dev, I2C_NACK);
 179     }
 180 }
 181
 182 static int i2c_slave_post_load(void *opaque, int version_id)
 183 {
 184     I2CSlave *dev = opaque;
 185     i2c_bus *bus;
 186     bus = FROM_QBUS(i2c_bus, qdev_get_parent_bus(&dev->qdev));
 187     if (bus->saved_address == dev->address) {
 188         bus->current_dev = dev;
 189     }
 190     return 0;
 191 }
 192
 193 const VMStateDescription vmstate_i2c_slave = {
 194     .name = "I2CSlave",
 195     .version_id = 1,
 196     .minimum_version_id = 1,
 197     .minimum_version_id_old = 1,
 198     .post_load = i2c_slave_post_load,
 199     .fields      = (VMStateField []) {
 200         VMSTATE_UINT8(address, I2CSlave),
 201         VMSTATE_END_OF_LIST()
 202     }
 203 };
 204
 205 static int i2c_slave_qdev_init(DeviceState *dev)
 206 {
 207     I2CSlave *s = I2C_SLAVE_FROM_QDEV(dev);
 208     I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(s);
 209
 210     return sc->init(s);
 211 }
 212
 213 DeviceState *i2c_create_slave(i2c_bus *bus, const char *name, uint8_t addr)
 214 {
 215     DeviceState *dev;
 216
 217     dev = qdev_create(&bus->qbus, name);
 218     qdev_prop_set_uint8(dev, "address", addr);
 219     qdev_init_nofail(dev);
 220     return dev;
 221 }
 222
 223 static void i2c_slave_class_init(ObjectClass *klass, void *data)
 224 {
 225     DeviceClass *k = DEVICE_CLASS(klass);
 226     k->init = i2c_slave_qdev_init;
 227     k->bus_type = TYPE_I2C_BUS;
 228     k->props = i2c_props;
 229 }
 230
 231 static const TypeInfo i2c_slave_type_info = {
 232     .name = TYPE_I2C_SLAVE,
 233     .parent = TYPE_DEVICE,
 234     .instance_size = sizeof(I2CSlave),
 235     .abstract = true,
 236     .class_size = sizeof(I2CSlaveClass),
 237     .class_init = i2c_slave_class_init,
 238 };
 239
 240 static void i2c_slave_register_types(void)
 241 {
 242     type_register_static(&i2c_bus_info);
 243     type_register_static(&i2c_slave_type_info);
 244 }
 245
 246 type_init(i2c_slave_register_types)