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 };
  24
  25 static void i2c_bus_save(QEMUFile *f, void *opaque)
  26 {
  27     i2c_bus *bus = (i2c_bus *)opaque;
  28
  29     qemu_put_byte(f, bus->current_dev ? bus->current_dev->address : -1);
  30 }
  31
  32 static int i2c_bus_load(QEMUFile *f, void *opaque, int version_id)
  33 {
  34     i2c_bus *bus = (i2c_bus *)opaque;
  35
  36     if (version_id != 1)
  37         return -EINVAL;
  38
  39     /* The bus is loaded before attached devices, so load and save the
  40        current device id.  Devices will check themselves as loaded.  */
  41     bus->saved_address = (int8_t) qemu_get_byte(f);
  42     bus->current_dev = NULL;
  43
  44     return 0;
  45 }
  46
  47 /* Create a new I2C bus.  */
  48 i2c_bus *i2c_init_bus(DeviceState *parent, const char *name)
  49 {
  50     i2c_bus *bus;
  51
  52     bus = FROM_QBUS(i2c_bus, qbus_create(&i2c_bus_info, parent, name));
  53     register_savevm("i2c_bus", -1, 1, i2c_bus_save, i2c_bus_load, bus);
  54     return bus;
  55 }
  56
  57 void i2c_set_slave_address(i2c_slave *dev, int address)
  58 {
  59     dev->address = address;
  60 }
  61
  62 /* Return nonzero if bus is busy.  */
  63 int i2c_bus_busy(i2c_bus *bus)
  64 {
  65     return bus->current_dev != NULL;
  66 }
  67
  68 /* Returns non-zero if the address is not valid.  */
  69 /* TODO: Make this handle multiple masters.  */
  70 int i2c_start_transfer(i2c_bus *bus, int address, int recv)
  71 {
  72     DeviceState *qdev;
  73     i2c_slave *slave = NULL;
  74
  75     LIST_FOREACH(qdev, &bus->qbus.children, sibling) {
  76         slave = I2C_SLAVE_FROM_QDEV(qdev);
  77         if (slave->address == address)
  78             break;
  79     }
  80
  81     if (!slave)
  82         return 1;
  83
  84     /* If the bus is already busy, assume this is a repeated
  85        start condition.  */
  86     bus->current_dev = slave;
  87     slave->info->event(slave, recv ? I2C_START_RECV : I2C_START_SEND);
  88     return 0;
  89 }
  90
  91 void i2c_end_transfer(i2c_bus *bus)
  92 {
  93     i2c_slave *dev = bus->current_dev;
  94
  95     if (!dev)
  96         return;
  97
  98     dev->info->event(dev, I2C_FINISH);
  99
 100     bus->current_dev = NULL;
 101 }
 102
 103 int i2c_send(i2c_bus *bus, uint8_t data)
 104 {
 105     i2c_slave *dev = bus->current_dev;
 106
 107     if (!dev)
 108         return -1;
 109
 110     return dev->info->send(dev, data);
 111 }
 112
 113 int i2c_recv(i2c_bus *bus)
 114 {
 115     i2c_slave *dev = bus->current_dev;
 116
 117     if (!dev)
 118         return -1;
 119
 120     return dev->info->recv(dev);
 121 }
 122
 123 void i2c_nack(i2c_bus *bus)
 124 {
 125     i2c_slave *dev = bus->current_dev;
 126
 127     if (!dev)
 128         return;
 129
 130     dev->info->event(dev, I2C_NACK);
 131 }
 132
 133 void i2c_slave_save(QEMUFile *f, i2c_slave *dev)
 134 {
 135     qemu_put_byte(f, dev->address);
 136 }
 137
 138 void i2c_slave_load(QEMUFile *f, i2c_slave *dev)
 139 {
 140     i2c_bus *bus;
 141     bus = FROM_QBUS(i2c_bus, qdev_get_parent_bus(&dev->qdev));
 142     dev->address = qemu_get_byte(f);
 143     if (bus->saved_address == dev->address) {
 144         bus->current_dev = dev;
 145     }
 146 }
 147
 148 static void i2c_slave_qdev_init(DeviceState *dev, DeviceInfo *base)
 149 {
 150     I2CSlaveInfo *info = container_of(base, I2CSlaveInfo, qdev);
 151     i2c_slave *s = I2C_SLAVE_FROM_QDEV(dev);
 152
 153     s->info = info;
 154     s->address = qdev_get_prop_int(dev, "address", 0);
 155
 156     info->init(s);
 157 }
 158
 159 void i2c_register_slave(I2CSlaveInfo *info)
 160 {
 161     assert(info->qdev.size >= sizeof(i2c_slave));
 162     info->qdev.init = i2c_slave_qdev_init;
 163     info->qdev.bus_info = &i2c_bus_info;
 164     qdev_register(&info->qdev);
 165 }
 166
 167 DeviceState *i2c_create_slave(i2c_bus *bus, const char *name, int addr)
 168 {
 169     DeviceState *dev;
 170
 171     dev = qdev_create(&bus->qbus, name);
 172     qdev_set_prop_int(dev, "address", addr);
 173     qdev_init(dev);
 174     return dev;
 175 }