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
  12 struct i2c_bus
  13 {
  14     BusState qbus;
  15     i2c_slave *current_dev;
  16     i2c_slave *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 i2c_slave, 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(i2c_slave *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     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
 105 void 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
 117 int 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
 127 int 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
 137 void 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
 147 static 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
 158 const 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
 170 static 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
 180 void 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
 188 DeviceState *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 }