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         {
  25             .name   = "address",
  26             .info   = &qdev_prop_uint32,
  27             .offset = offsetof(struct i2c_slave, address),
  28         },
  29         {/* end of list */}
  30     }
  31 };
  32
  33 static void i2c_bus_save(QEMUFile *f, void *opaque)
  34 {
  35     i2c_bus *bus = (i2c_bus *)opaque;
  36
  37     qemu_put_byte(f, bus->current_dev ? bus->current_dev->address : -1);
  38 }
  39
  40 static int i2c_bus_load(QEMUFile *f, void *opaque, int version_id)
  41 {
  42     i2c_bus *bus = (i2c_bus *)opaque;
  43
  44     if (version_id != 1)
  45         return -EINVAL;
  46
  47     /* The bus is loaded before attached devices, so load and save the
  48        current device id.  Devices will check themselves as loaded.  */
  49     bus->saved_address = (int8_t) qemu_get_byte(f);
  50     bus->current_dev = NULL;
  51
  52     return 0;
  53 }
  54
  55 /* Create a new I2C bus.  */
  56 i2c_bus *i2c_init_bus(DeviceState *parent, const char *name)
  57 {
  58     i2c_bus *bus;
  59
  60     bus = FROM_QBUS(i2c_bus, qbus_create(&i2c_bus_info, parent, name));
  61     register_savevm("i2c_bus", -1, 1, i2c_bus_save, i2c_bus_load, bus);
  62     return bus;
  63 }
  64
  65 void i2c_set_slave_address(i2c_slave *dev, int address)
  66 {
  67     dev->address = address;
  68 }
  69
  70 /* Return nonzero if bus is busy.  */
  71 int i2c_bus_busy(i2c_bus *bus)
  72 {
  73     return bus->current_dev != NULL;
  74 }
  75
  76 /* Returns non-zero if the address is not valid.  */
  77 /* TODO: Make this handle multiple masters.  */
  78 int i2c_start_transfer(i2c_bus *bus, int address, int recv)
  79 {
  80     DeviceState *qdev;
  81     i2c_slave *slave = NULL;
  82
  83     LIST_FOREACH(qdev, &bus->qbus.children, sibling) {
  84         slave = I2C_SLAVE_FROM_QDEV(qdev);
  85         if (slave->address == address)
  86             break;
  87     }
  88
  89     if (!slave)
  90         return 1;
  91
  92     /* If the bus is already busy, assume this is a repeated
  93        start condition.  */
  94     bus->current_dev = slave;
  95     slave->info->event(slave, recv ? I2C_START_RECV : I2C_START_SEND);
  96     return 0;
  97 }
  98
  99 void i2c_end_transfer(i2c_bus *bus)
 100 {
 101     i2c_slave *dev = bus->current_dev;
 102
 103     if (!dev)
 104         return;
 105
 106     dev->info->event(dev, I2C_FINISH);
 107
 108     bus->current_dev = NULL;
 109 }
 110
 111 int i2c_send(i2c_bus *bus, uint8_t data)
 112 {
 113     i2c_slave *dev = bus->current_dev;
 114
 115     if (!dev)
 116         return -1;
 117
 118     return dev->info->send(dev, data);
 119 }
 120
 121 int i2c_recv(i2c_bus *bus)
 122 {
 123     i2c_slave *dev = bus->current_dev;
 124
 125     if (!dev)
 126         return -1;
 127
 128     return dev->info->recv(dev);
 129 }
 130
 131 void i2c_nack(i2c_bus *bus)
 132 {
 133     i2c_slave *dev = bus->current_dev;
 134
 135     if (!dev)
 136         return;
 137
 138     dev->info->event(dev, I2C_NACK);
 139 }
 140
 141 void i2c_slave_save(QEMUFile *f, i2c_slave *dev)
 142 {
 143     qemu_put_byte(f, dev->address);
 144 }
 145
 146 void i2c_slave_load(QEMUFile *f, i2c_slave *dev)
 147 {
 148     i2c_bus *bus;
 149     bus = FROM_QBUS(i2c_bus, qdev_get_parent_bus(&dev->qdev));
 150     dev->address = qemu_get_byte(f);
 151     if (bus->saved_address == dev->address) {
 152         bus->current_dev = dev;
 153     }
 154 }
 155
 156 static void i2c_slave_qdev_init(DeviceState *dev, DeviceInfo *base)
 157 {
 158     I2CSlaveInfo *info = container_of(base, I2CSlaveInfo, qdev);
 159     i2c_slave *s = I2C_SLAVE_FROM_QDEV(dev);
 160
 161     s->info = info;
 162
 163     info->init(s);
 164 }
 165
 166 void i2c_register_slave(I2CSlaveInfo *info)
 167 {
 168     assert(info->qdev.size >= sizeof(i2c_slave));
 169     info->qdev.init = i2c_slave_qdev_init;
 170     info->qdev.bus_info = &i2c_bus_info;
 171     qdev_register(&info->qdev);
 172 }
 173
 174 DeviceState *i2c_create_slave(i2c_bus *bus, const char *name, int addr)
 175 {
 176     DeviceState *dev;
 177
 178     dev = qdev_create(&bus->qbus, name);
 179     qdev_prop_set_uint32(dev, "address", addr);
 180     qdev_init(dev);
 181     return dev;
 182 }