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 struct BusInfo i2c_bus_info = {
  21     .name = "I2C",
  22     .size = sizeof(i2c_bus),
  23     .props = (Property[]) {
  24         DEFINE_PROP_UINT8("address", struct I2CSlave, address, 0),
  25         DEFINE_PROP_END_OF_LIST(),
  26     }
  27 };
  28
  29 static 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
  36 static 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
  46 static 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.  */
  60 i2c_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
  69 void i2c_set_slave_address(I2CSlave *dev, uint8_t address)
  70 {
  71     dev->address = address;
  72 }
  73
  74 /* Return nonzero if bus is busy.  */
  75 int 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.  */
  82 int i2c_start_transfer(i2c_bus *bus, uint8_t address, int recv)
  83 {
  84     DeviceState *qdev;
  85     I2CSlave *slave = NULL;
  86     I2CSlaveClass *sc;
  87
  88     QTAILQ_FOREACH(qdev, &bus->qbus.children, sibling) {
  89         I2CSlave *candidate = I2C_SLAVE_FROM_QDEV(qdev);
  90         if (candidate->address == address) {
  91             slave = candidate;
  92             break;
  93         }
  94     }
  95
  96     if (!slave) {
  97         return 1;
  98     }
  99
 100     sc = I2C_SLAVE_GET_CLASS(slave);
 101     /* If the bus is already busy, assume this is a repeated
 102        start condition.  */
 103     bus->current_dev = slave;
 104     if (sc->event) {
 105         sc->event(slave, recv ? I2C_START_RECV : I2C_START_SEND);
 106     }
 107     return 0;
 108 }
 109
 110 void i2c_end_transfer(i2c_bus *bus)
 111 {
 112     I2CSlave *dev = bus->current_dev;
 113     I2CSlaveClass *sc;
 114
 115     if (!dev) {
 116         return;
 117     }
 118
 119     sc = I2C_SLAVE_GET_CLASS(dev);
 120     if (sc->event) {
 121         sc->event(dev, I2C_FINISH);
 122     }
 123
 124     bus->current_dev = NULL;
 125 }
 126
 127 int i2c_send(i2c_bus *bus, uint8_t data)
 128 {
 129     I2CSlave *dev = bus->current_dev;
 130     I2CSlaveClass *sc;
 131
 132     if (!dev) {
 133         return -1;
 134     }
 135
 136     sc = I2C_SLAVE_GET_CLASS(dev);
 137     if (sc->send) {
 138         return sc->send(dev, data);
 139     }
 140
 141     return -1;
 142 }
 143
 144 int i2c_recv(i2c_bus *bus)
 145 {
 146     I2CSlave *dev = bus->current_dev;
 147     I2CSlaveClass *sc;
 148
 149     if (!dev) {
 150         return -1;
 151     }
 152
 153     sc = I2C_SLAVE_GET_CLASS(dev);
 154     if (sc->recv) {
 155         return sc->recv(dev);
 156     }
 157
 158     return -1;
 159 }
 160
 161 void i2c_nack(i2c_bus *bus)
 162 {
 163     I2CSlave *dev = bus->current_dev;
 164     I2CSlaveClass *sc;
 165
 166     if (!dev) {
 167         return;
 168     }
 169
 170     sc = I2C_SLAVE_GET_CLASS(dev);
 171     if (sc->event) {
 172         sc->event(dev, I2C_NACK);
 173     }
 174 }
 175
 176 static int i2c_slave_post_load(void *opaque, int version_id)
 177 {
 178     I2CSlave *dev = opaque;
 179     i2c_bus *bus;
 180     bus = FROM_QBUS(i2c_bus, qdev_get_parent_bus(&dev->qdev));
 181     if (bus->saved_address == dev->address) {
 182         bus->current_dev = dev;
 183     }
 184     return 0;
 185 }
 186
 187 const VMStateDescription vmstate_i2c_slave = {
 188     .name = "I2CSlave",
 189     .version_id = 1,
 190     .minimum_version_id = 1,
 191     .minimum_version_id_old = 1,
 192     .post_load = i2c_slave_post_load,
 193     .fields      = (VMStateField []) {
 194         VMSTATE_UINT8(address, I2CSlave),
 195         VMSTATE_END_OF_LIST()
 196     }
 197 };
 198
 199 static int i2c_slave_qdev_init(DeviceState *dev, DeviceInfo *base)
 200 {
 201     I2CSlave *s = I2C_SLAVE_FROM_QDEV(dev);
 202     I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(s);
 203
 204     return sc->init(s);
 205 }
 206
 207 void i2c_register_slave_subclass(DeviceInfo *info, const char *parent)
 208 {
 209     assert(info->size >= sizeof(I2CSlave));
 210     info->init = i2c_slave_qdev_init;
 211     info->bus_info = &i2c_bus_info;
 212     qdev_register_subclass(info, parent);
 213 }
 214
 215 void i2c_register_slave(DeviceInfo *info)
 216 {
 217     i2c_register_slave_subclass(info, TYPE_I2C_SLAVE);
 218 }
 219
 220 DeviceState *i2c_create_slave(i2c_bus *bus, const char *name, uint8_t addr)
 221 {
 222     DeviceState *dev;
 223
 224     dev = qdev_create(&bus->qbus, name);
 225     qdev_prop_set_uint8(dev, "address", addr);
 226     qdev_init_nofail(dev);
 227     return dev;
 228 }
 229
 230 static TypeInfo i2c_slave_type_info = {
 231     .name = TYPE_I2C_SLAVE,
 232     .parent = TYPE_DEVICE,
 233     .instance_size = sizeof(I2CSlave),
 234     .abstract = true,
 235     .class_size = sizeof(I2CSlaveClass),
 236 };
 237
 238 static void i2c_slave_register_devices(void)
 239 {
 240     type_register_static(&i2c_slave_type_info);
 241 }
 242
 243 device_init(i2c_slave_register_devices);