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     int 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_UINT32("address", struct i2c_slave, address, 0),
  25         DEFINE_PROP_END_OF_LIST(),
  26     }
  27 };
  28
  29 static void i2c_bus_save(QEMUFile *f, void *opaque)
  30 {
  31     i2c_bus *bus = (i2c_bus *)opaque;
  32
  33     qemu_put_byte(f, bus->current_dev ? bus->current_dev->address : -1);
  34 }
  35
  36 static int i2c_bus_load(QEMUFile *f, void *opaque, int version_id)
  37 {
  38     i2c_bus *bus = (i2c_bus *)opaque;
  39
  40     if (version_id != 1)
  41         return -EINVAL;
  42
  43     /* The bus is loaded before attached devices, so load and save the
  44        current device id.  Devices will check themselves as loaded.  */
  45     bus->saved_address = (int8_t) qemu_get_byte(f);
  46     bus->current_dev = NULL;
  47
  48     return 0;
  49 }
  50
  51 /* Create a new I2C bus.  */
  52 i2c_bus *i2c_init_bus(DeviceState *parent, const char *name)
  53 {
  54     i2c_bus *bus;
  55
  56     bus = FROM_QBUS(i2c_bus, qbus_create(&i2c_bus_info, parent, name));
  57     register_savevm("i2c_bus", -1, 1, i2c_bus_save, i2c_bus_load, bus);
  58     return bus;
  59 }
  60
  61 void i2c_set_slave_address(i2c_slave *dev, int address)
  62 {
  63     dev->address = address;
  64 }
  65
  66 /* Return nonzero if bus is busy.  */
  67 int i2c_bus_busy(i2c_bus *bus)
  68 {
  69     return bus->current_dev != NULL;
  70 }
  71
  72 /* Returns non-zero if the address is not valid.  */
  73 /* TODO: Make this handle multiple masters.  */
  74 int i2c_start_transfer(i2c_bus *bus, int address, int recv)
  75 {
  76     DeviceState *qdev;
  77     i2c_slave *slave = NULL;
  78
  79     LIST_FOREACH(qdev, &bus->qbus.children, sibling) {
  80         slave = I2C_SLAVE_FROM_QDEV(qdev);
  81         if (slave->address == address)
  82             break;
  83     }
  84
  85     if (!slave)
  86         return 1;
  87
  88     /* If the bus is already busy, assume this is a repeated
  89        start condition.  */
  90     bus->current_dev = slave;
  91     slave->info->event(slave, recv ? I2C_START_RECV : I2C_START_SEND);
  92     return 0;
  93 }
  94
  95 void i2c_end_transfer(i2c_bus *bus)
  96 {
  97     i2c_slave *dev = bus->current_dev;
  98
  99     if (!dev)
 100         return;
 101
 102     dev->info->event(dev, I2C_FINISH);
 103
 104     bus->current_dev = NULL;
 105 }
 106
 107 int i2c_send(i2c_bus *bus, uint8_t data)
 108 {
 109     i2c_slave *dev = bus->current_dev;
 110
 111     if (!dev)
 112         return -1;
 113
 114     return dev->info->send(dev, data);
 115 }
 116
 117 int i2c_recv(i2c_bus *bus)
 118 {
 119     i2c_slave *dev = bus->current_dev;
 120
 121     if (!dev)
 122         return -1;
 123
 124     return dev->info->recv(dev);
 125 }
 126
 127 void i2c_nack(i2c_bus *bus)
 128 {
 129     i2c_slave *dev = bus->current_dev;
 130
 131     if (!dev)
 132         return;
 133
 134     dev->info->event(dev, I2C_NACK);
 135 }
 136
 137 void i2c_slave_save(QEMUFile *f, i2c_slave *dev)
 138 {
 139     qemu_put_byte(f, dev->address);
 140 }
 141
 142 void i2c_slave_load(QEMUFile *f, i2c_slave *dev)
 143 {
 144     i2c_bus *bus;
 145     bus = FROM_QBUS(i2c_bus, qdev_get_parent_bus(&dev->qdev));
 146     dev->address = qemu_get_byte(f);
 147     if (bus->saved_address == dev->address) {
 148         bus->current_dev = dev;
 149     }
 150 }
 151
 152 static void i2c_slave_qdev_init(DeviceState *dev, DeviceInfo *base)
 153 {
 154     I2CSlaveInfo *info = container_of(base, I2CSlaveInfo, qdev);
 155     i2c_slave *s = I2C_SLAVE_FROM_QDEV(dev);
 156
 157     s->info = info;
 158
 159     info->init(s);
 160 }
 161
 162 void i2c_register_slave(I2CSlaveInfo *info)
 163 {
 164     assert(info->qdev.size >= sizeof(i2c_slave));
 165     info->qdev.init = i2c_slave_qdev_init;
 166     info->qdev.bus_info = &i2c_bus_info;
 167     qdev_register(&info->qdev);
 168 }
 169
 170 DeviceState *i2c_create_slave(i2c_bus *bus, const char *name, int addr)
 171 {
 172     DeviceState *dev;
 173
 174     dev = qdev_create(&bus->qbus, name);
 175     qdev_prop_set_uint32(dev, "address", addr);
 176     qdev_init(dev);
 177     return dev;
 178 }