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 void i2c_bus_save(QEMUFile *f, void *opaque)
  21 {
  22     i2c_bus *bus = (i2c_bus *)opaque;
  23
  24     qemu_put_byte(f, bus->current_dev ? bus->current_dev->address : -1);
  25 }
  26
  27 static int i2c_bus_load(QEMUFile *f, void *opaque, int version_id)
  28 {
  29     i2c_bus *bus = (i2c_bus *)opaque;
  30
  31     if (version_id != 1)
  32         return -EINVAL;
  33
  34     /* The bus is loaded before attached devices, so load and save the
  35        current device id.  Devices will check themselves as loaded.  */
  36     bus->saved_address = (int8_t) qemu_get_byte(f);
  37     bus->current_dev = NULL;
  38
  39     return 0;
  40 }
  41
  42 /* Create a new I2C bus.  */
  43 i2c_bus *i2c_init_bus(DeviceState *parent, const char *name)
  44 {
  45     i2c_bus *bus;
  46
  47     bus = FROM_QBUS(i2c_bus, qbus_create(BUS_TYPE_I2C, sizeof(i2c_bus),
  48                                          parent, name));
  49     register_savevm("i2c_bus", -1, 1, i2c_bus_save, i2c_bus_load, bus);
  50     return bus;
  51 }
  52
  53 void i2c_set_slave_address(i2c_slave *dev, int address)
  54 {
  55     dev->address = address;
  56 }
  57
  58 /* Return nonzero if bus is busy.  */
  59 int i2c_bus_busy(i2c_bus *bus)
  60 {
  61     return bus->current_dev != NULL;
  62 }
  63
  64 /* Returns non-zero if the address is not valid.  */
  65 /* TODO: Make this handle multiple masters.  */
  66 int i2c_start_transfer(i2c_bus *bus, int address, int recv)
  67 {
  68     DeviceState *qdev;
  69     i2c_slave *slave = NULL;
  70
  71     LIST_FOREACH(qdev, &bus->qbus.children, sibling) {
  72         slave = I2C_SLAVE_FROM_QDEV(qdev);
  73         if (slave->address == address)
  74             break;
  75     }
  76
  77     if (!slave)
  78         return 1;
  79
  80     /* If the bus is already busy, assume this is a repeated
  81        start condition.  */
  82     bus->current_dev = slave;
  83     slave->info->event(slave, recv ? I2C_START_RECV : I2C_START_SEND);
  84     return 0;
  85 }
  86
  87 void i2c_end_transfer(i2c_bus *bus)
  88 {
  89     i2c_slave *dev = bus->current_dev;
  90
  91     if (!dev)
  92         return;
  93
  94     dev->info->event(dev, I2C_FINISH);
  95
  96     bus->current_dev = NULL;
  97 }
  98
  99 int i2c_send(i2c_bus *bus, uint8_t data)
 100 {
 101     i2c_slave *dev = bus->current_dev;
 102
 103     if (!dev)
 104         return -1;
 105
 106     return dev->info->send(dev, data);
 107 }
 108
 109 int i2c_recv(i2c_bus *bus)
 110 {
 111     i2c_slave *dev = bus->current_dev;
 112
 113     if (!dev)
 114         return -1;
 115
 116     return dev->info->recv(dev);
 117 }
 118
 119 void i2c_nack(i2c_bus *bus)
 120 {
 121     i2c_slave *dev = bus->current_dev;
 122
 123     if (!dev)
 124         return;
 125
 126     dev->info->event(dev, I2C_NACK);
 127 }
 128
 129 void i2c_slave_save(QEMUFile *f, i2c_slave *dev)
 130 {
 131     qemu_put_byte(f, dev->address);
 132 }
 133
 134 void i2c_slave_load(QEMUFile *f, i2c_slave *dev)
 135 {
 136     i2c_bus *bus;
 137     bus = FROM_QBUS(i2c_bus, qdev_get_parent_bus(&dev->qdev));
 138     dev->address = qemu_get_byte(f);
 139     if (bus->saved_address == dev->address) {
 140         bus->current_dev = dev;
 141     }
 142 }
 143
 144 static void i2c_slave_qdev_init(DeviceState *dev, DeviceInfo *base)
 145 {
 146     I2CSlaveInfo *info = container_of(base, I2CSlaveInfo, qdev);
 147     i2c_slave *s = I2C_SLAVE_FROM_QDEV(dev);
 148
 149     s->info = info;
 150     s->address = qdev_get_prop_int(dev, "address", 0);
 151
 152     info->init(s);
 153 }
 154
 155 void i2c_register_slave(I2CSlaveInfo *info)
 156 {
 157     assert(info->qdev.size >= sizeof(i2c_slave));
 158     info->qdev.init = i2c_slave_qdev_init;
 159     info->qdev.bus_type = BUS_TYPE_I2C;
 160     qdev_register(&info->qdev);
 161 }
 162
 163 DeviceState *i2c_create_slave(i2c_bus *bus, const char *name, int addr)
 164 {
 165     DeviceState *dev;
 166
 167     dev = qdev_create(&bus->qbus, name);
 168     qdev_set_prop_int(dev, "address", addr);
 169     qdev_init(dev);
 170     return dev;
 171 }