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 void i2c_set_slave_address(i2c_slave *dev, int address)
  52 {
  53     dev->address = address;
  54 }
  55
  56 /* Return nonzero if bus is busy.  */
  57 int i2c_bus_busy(i2c_bus *bus)
  58 {
  59     return bus->current_dev != NULL;
  60 }
  61
  62 /* Returns non-zero if the address is not valid.  */
  63 /* TODO: Make this handle multiple masters.  */
  64 int i2c_start_transfer(i2c_bus *bus, int address, int recv)
  65 {
  66     i2c_slave *dev;
  67
  68     for (dev = bus->dev; dev; dev = dev->next) {
  69         if (dev->address == address)
  70             break;
  71     }
  72
  73     if (!dev)
  74         return 1;
  75
  76     /* If the bus is already busy, assume this is a repeated
  77        start condition.  */
  78     bus->current_dev = dev;
  79     dev->info->event(dev, recv ? I2C_START_RECV : I2C_START_SEND);
  80     return 0;
  81 }
  82
  83 void i2c_end_transfer(i2c_bus *bus)
  84 {
  85     i2c_slave *dev = bus->current_dev;
  86
  87     if (!dev)
  88         return;
  89
  90     dev->info->event(dev, I2C_FINISH);
  91
  92     bus->current_dev = NULL;
  93 }
  94
  95 int i2c_send(i2c_bus *bus, uint8_t data)
  96 {
  97     i2c_slave *dev = bus->current_dev;
  98
  99     if (!dev)
 100         return -1;
 101
 102     return dev->info->send(dev, data);
 103 }
 104
 105 int i2c_recv(i2c_bus *bus)
 106 {
 107     i2c_slave *dev = bus->current_dev;
 108
 109     if (!dev)
 110         return -1;
 111
 112     return dev->info->recv(dev);
 113 }
 114
 115 void i2c_nack(i2c_bus *bus)
 116 {
 117     i2c_slave *dev = bus->current_dev;
 118
 119     if (!dev)
 120         return;
 121
 122     dev->info->event(dev, I2C_NACK);
 123 }
 124
 125 void i2c_slave_save(QEMUFile *f, i2c_slave *dev)
 126 {
 127     qemu_put_byte(f, dev->address);
 128 }
 129
 130 void i2c_slave_load(QEMUFile *f, i2c_slave *dev)
 131 {
 132     i2c_bus *bus;
 133     bus = qdev_get_bus(&dev->qdev);
 134     dev->address = qemu_get_byte(f);
 135     if (bus->saved_address == dev->address) {
 136         bus->current_dev = dev;
 137     }
 138 }
 139
 140 static void i2c_slave_qdev_init(DeviceState *dev, void *opaque)
 141 {
 142     I2CSlaveInfo *info = opaque;
 143     i2c_slave *s = I2C_SLAVE_FROM_QDEV(dev);
 144
 145     s->info = info;
 146     s->bus = qdev_get_bus(dev);
 147     s->address = qdev_get_prop_int(dev, "address", 0);
 148     s->next = s->bus->dev;
 149     s->bus->dev = s;
 150
 151     info->init(s);
 152 }
 153
 154 void i2c_register_slave(const char *name, int size, I2CSlaveInfo *info)
 155 {
 156     assert(size >= sizeof(i2c_slave));
 157     qdev_register(name, size, i2c_slave_qdev_init, info);
 158 }
 159
 160 DeviceState *i2c_create_slave(i2c_bus *bus, const char *name, int addr)
 161 {
 162     DeviceState *dev;
 163
 164     dev = qdev_create(bus, name);
 165     qdev_set_prop_int(dev, "address", addr);
 166     qdev_init(dev);
 167     return dev;
 168 }