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     i2c_slave *current_dev;
  15     i2c_slave *dev;
  16     int saved_address;
  17 };
  18
  19 static void i2c_bus_save(QEMUFile *f, void *opaque)
  20 {
  21     i2c_bus *bus = (i2c_bus *)opaque;
  22
  23     qemu_put_byte(f, bus->current_dev ? bus->current_dev->address : -1);
  24 }
  25
  26 static int i2c_bus_load(QEMUFile *f, void *opaque, int version_id)
  27 {
  28     i2c_bus *bus = (i2c_bus *)opaque;
  29
  30     if (version_id != 1)
  31         return -EINVAL;
  32
  33     /* The bus is loaded before attached devices, so load and save the
  34        current device id.  Devices will check themselves as loaded.  */
  35     bus->saved_address = (int8_t) qemu_get_byte(f);
  36     bus->current_dev = NULL;
  37
  38     return 0;
  39 }
  40
  41 /* Create a new I2C bus.  */
  42 i2c_bus *i2c_init_bus(void)
  43 {
  44     i2c_bus *bus;
  45
  46     bus = (i2c_bus *)qemu_mallocz(sizeof(i2c_bus));
  47     register_savevm("i2c_bus", -1, 1, i2c_bus_save, i2c_bus_load, bus);
  48     return bus;
  49 }
  50
  51 /* Create a new slave device.  */
  52 i2c_slave *i2c_slave_init(i2c_bus *bus, int address, int size)
  53 {
  54     i2c_slave *dev;
  55
  56     if (size < sizeof(i2c_slave))
  57         hw_error("I2C struct too small");
  58
  59     dev = (i2c_slave *)qemu_mallocz(size);
  60     dev->address = address;
  61     dev->next = bus->dev;
  62     bus->dev = dev;
  63     dev->qdev.bus = bus;
  64
  65     return dev;
  66 }
  67
  68 void i2c_set_slave_address(i2c_slave *dev, int address)
  69 {
  70     dev->address = address;
  71 }
  72
  73 /* Return nonzero if bus is busy.  */
  74 int i2c_bus_busy(i2c_bus *bus)
  75 {
  76     return bus->current_dev != NULL;
  77 }
  78
  79 /* Returns non-zero if the address is not valid.  */
  80 /* TODO: Make this handle multiple masters.  */
  81 int i2c_start_transfer(i2c_bus *bus, int address, int recv)
  82 {
  83     i2c_slave *dev;
  84
  85     for (dev = bus->dev; dev; dev = dev->next) {
  86         if (dev->address == address)
  87             break;
  88     }
  89
  90     if (!dev)
  91         return 1;
  92
  93     /* If the bus is already busy, assume this is a repeated
  94        start condition.  */
  95     bus->current_dev = dev;
  96     dev->info->event(dev, recv ? I2C_START_RECV : I2C_START_SEND);
  97     return 0;
  98 }
  99
 100 void i2c_end_transfer(i2c_bus *bus)
 101 {
 102     i2c_slave *dev = bus->current_dev;
 103
 104     if (!dev)
 105         return;
 106
 107     dev->info->event(dev, I2C_FINISH);
 108
 109     bus->current_dev = NULL;
 110 }
 111
 112 int i2c_send(i2c_bus *bus, uint8_t data)
 113 {
 114     i2c_slave *dev = bus->current_dev;
 115
 116     if (!dev)
 117         return -1;
 118
 119     return dev->info->send(dev, data);
 120 }
 121
 122 int i2c_recv(i2c_bus *bus)
 123 {
 124     i2c_slave *dev = bus->current_dev;
 125
 126     if (!dev)
 127         return -1;
 128
 129     return dev->info->recv(dev);
 130 }
 131
 132 void i2c_nack(i2c_bus *bus)
 133 {
 134     i2c_slave *dev = bus->current_dev;
 135
 136     if (!dev)
 137         return;
 138
 139     dev->info->event(dev, I2C_NACK);
 140 }
 141
 142 void i2c_slave_save(QEMUFile *f, i2c_slave *dev)
 143 {
 144     qemu_put_byte(f, dev->address);
 145 }
 146
 147 void i2c_slave_load(QEMUFile *f, i2c_slave *dev)
 148 {
 149     i2c_bus *bus;
 150     bus = qdev_get_bus(&dev->qdev);
 151     dev->address = qemu_get_byte(f);
 152     if (bus->saved_address == dev->address) {
 153         bus->current_dev = dev;
 154     }
 155 }
 156
 157 static void i2c_slave_qdev_init(DeviceState *dev, void *opaque)
 158 {
 159     I2CSlaveInfo *info = opaque;
 160     i2c_slave *s = I2C_SLAVE_FROM_QDEV(dev);
 161
 162     s->info = info;
 163     s->bus = qdev_get_bus(dev);
 164     s->address = qdev_get_prop_int(dev, "address", 0);
 165     s->next = s->bus->dev;
 166     s->bus->dev = s;
 167
 168     s->event = info->event;
 169     s->recv = info->recv;
 170     s->send = info->send;
 171
 172     info->init(s);
 173 }
 174
 175 void i2c_register_slave(const char *name, int size, I2CSlaveInfo *info)
 176 {
 177     assert(size >= sizeof(i2c_slave));
 178     qdev_register(name, size, i2c_slave_qdev_init, info);
 179 }
 180
 181 DeviceState *i2c_create_slave(i2c_bus *bus, const char *name, int addr)
 182 {
 183     DeviceState *dev;
 184
 185     dev = qdev_create(bus, name);
 186     qdev_set_prop_int(dev, "address", addr);
 187     qdev_init(dev);
 188     return dev;
 189 }