hw/i2c/core.c

   1 /*
   2  * QEMU I2C bus interface.
   3  *
   4  * Copyright (c) 2007 CodeSourcery.
   5  * Written by Paul Brook
   6  *
   7  * This code is licensed under the LGPL.
   8  */
   9
  10 #include "qemu/osdep.h"
  11 #include "hw/i2c/i2c.h"
  12
  13 typedef struct I2CNode I2CNode;
  14
  15 struct I2CNode {
  16     I2CSlave *elt;
  17     QLIST_ENTRY(I2CNode) next;
  18 };
  19
  20 #define I2C_BROADCAST 0x00
  21
  22 struct I2CBus
  23 {
  24     BusState qbus;
  25     QLIST_HEAD(, I2CNode) current_devs;
  26     uint8_t saved_address;
  27     bool broadcast;
  28 };
  29
  30 static Property i2c_props[] = {
  31     DEFINE_PROP_UINT8("address", struct I2CSlave, address, 0),
  32     DEFINE_PROP_END_OF_LIST(),
  33 };
  34
  35 #define TYPE_I2C_BUS "i2c-bus"
  36 #define I2C_BUS(obj) OBJECT_CHECK(I2CBus, (obj), TYPE_I2C_BUS)
  37
  38 static const TypeInfo i2c_bus_info = {
  39     .name = TYPE_I2C_BUS,
  40     .parent = TYPE_BUS,
  41     .instance_size = sizeof(I2CBus),
  42 };
  43
  44 static void i2c_bus_pre_save(void *opaque)
  45 {
  46     I2CBus *bus = opaque;
  47
  48     bus->saved_address = -1;
  49     if (!QLIST_EMPTY(&bus->current_devs)) {
  50         if (!bus->broadcast) {
  51             bus->saved_address = QLIST_FIRST(&bus->current_devs)->elt->address;
  52         } else {
  53             bus->saved_address = I2C_BROADCAST;
  54         }
  55     }
  56 }
  57
  58 static const VMStateDescription vmstate_i2c_bus = {
  59     .name = "i2c_bus",
  60     .version_id = 1,
  61     .minimum_version_id = 1,
  62     .pre_save = i2c_bus_pre_save,
  63     .fields = (VMStateField[]) {
  64         VMSTATE_UINT8(saved_address, I2CBus),
  65         VMSTATE_END_OF_LIST()
  66     }
  67 };
  68
  69 /* Create a new I2C bus.  */
  70 I2CBus *i2c_init_bus(DeviceState *parent, const char *name)
  71 {
  72     I2CBus *bus;
  73
  74     bus = I2C_BUS(qbus_create(TYPE_I2C_BUS, parent, name));
  75     QLIST_INIT(&bus->current_devs);
  76     vmstate_register(NULL, -1, &vmstate_i2c_bus, bus);
  77     return bus;
  78 }
  79
  80 void i2c_set_slave_address(I2CSlave *dev, uint8_t address)
  81 {
  82     dev->address = address;
  83 }
  84
  85 /* Return nonzero if bus is busy.  */
  86 int i2c_bus_busy(I2CBus *bus)
  87 {
  88     return !QLIST_EMPTY(&bus->current_devs);
  89 }
  90
  91 /* Returns non-zero if the address is not valid.  */
  92 /* TODO: Make this handle multiple masters.  */
  93 int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
  94 {
  95     BusChild *kid;
  96     I2CSlaveClass *sc;
  97     I2CNode *node;
  98
  99     if (address == I2C_BROADCAST) {
 100         /*
 101          * This is a broadcast, the current_devs will be all the devices of the
 102          * bus.
 103          */
 104         bus->broadcast = true;
 105     }
 106
 107     /*
 108      * If there are already devices in the list, that means we are in
 109      * the middle of a transaction and we shouldn't rescan the bus.
 110      *
 111      * This happens with any SMBus transaction, even on a pure I2C
 112      * device.  The interface does a transaction start without
 113      * terminating the previous transaction.
 114      */
 115     if (QLIST_EMPTY(&bus->current_devs)) {
 116         QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
 117             DeviceState *qdev = kid->child;
 118             I2CSlave *candidate = I2C_SLAVE(qdev);
 119             if ((candidate->address == address) || (bus->broadcast)) {
 120                 node = g_malloc(sizeof(struct I2CNode));
 121                 node->elt = candidate;
 122                 QLIST_INSERT_HEAD(&bus->current_devs, node, next);
 123                 if (!bus->broadcast) {
 124                     break;
 125                 }
 126             }
 127         }
 128     }
 129
 130     if (QLIST_EMPTY(&bus->current_devs)) {
 131         return 1;
 132     }
 133
 134     QLIST_FOREACH(node, &bus->current_devs, next) {
 135         sc = I2C_SLAVE_GET_CLASS(node->elt);
 136         /* If the bus is already busy, assume this is a repeated
 137            start condition.  */
 138         if (sc->event) {
 139             sc->event(node->elt, recv ? I2C_START_RECV : I2C_START_SEND);
 140         }
 141     }
 142     return 0;
 143 }
 144
 145 void i2c_end_transfer(I2CBus *bus)
 146 {
 147     I2CSlaveClass *sc;
 148     I2CNode *node, *next;
 149
 150     QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) {
 151         sc = I2C_SLAVE_GET_CLASS(node->elt);
 152         if (sc->event) {
 153             sc->event(node->elt, I2C_FINISH);
 154         }
 155         QLIST_REMOVE(node, next);
 156         g_free(node);
 157     }
 158     bus->broadcast = false;
 159 }
 160
 161 int i2c_send_recv(I2CBus *bus, uint8_t *data, bool send)
 162 {
 163     I2CSlaveClass *sc;
 164     I2CNode *node;
 165     int ret = 0;
 166
 167     if (send) {
 168         QLIST_FOREACH(node, &bus->current_devs, next) {
 169             sc = I2C_SLAVE_GET_CLASS(node->elt);
 170             if (sc->send) {
 171                 ret = ret || sc->send(node->elt, *data);
 172             } else {
 173                 ret = -1;
 174             }
 175         }
 176         return ret ? -1 : 0;
 177     } else {
 178         if ((QLIST_EMPTY(&bus->current_devs)) || (bus->broadcast)) {
 179             return -1;
 180         }
 181
 182         sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
 183         if (sc->recv) {
 184             ret = sc->recv(QLIST_FIRST(&bus->current_devs)->elt);
 185             if (ret < 0) {
 186                 return ret;
 187             } else {
 188                 *data = ret;
 189                 return 0;
 190             }
 191         }
 192         return -1;
 193     }
 194 }
 195
 196 int i2c_send(I2CBus *bus, uint8_t data)
 197 {
 198     return i2c_send_recv(bus, &data, true);
 199 }
 200
 201 int i2c_recv(I2CBus *bus)
 202 {
 203     uint8_t data;
 204     int ret = i2c_send_recv(bus, &data, false);
 205
 206     return ret < 0 ? ret : data;
 207 }
 208
 209 void i2c_nack(I2CBus *bus)
 210 {
 211     I2CSlaveClass *sc;
 212     I2CNode *node;
 213
 214     if (QLIST_EMPTY(&bus->current_devs)) {
 215         return;
 216     }
 217
 218     QLIST_FOREACH(node, &bus->current_devs, next) {
 219         sc = I2C_SLAVE_GET_CLASS(node->elt);
 220         if (sc->event) {
 221             sc->event(node->elt, I2C_NACK);
 222         }
 223     }
 224 }
 225
 226 static int i2c_slave_post_load(void *opaque, int version_id)
 227 {
 228     I2CSlave *dev = opaque;
 229     I2CBus *bus;
 230     I2CNode *node;
 231
 232     bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev)));
 233     if ((bus->saved_address == dev->address) ||
 234         (bus->saved_address == I2C_BROADCAST)) {
 235         node = g_malloc(sizeof(struct I2CNode));
 236         node->elt = dev;
 237         QLIST_INSERT_HEAD(&bus->current_devs, node, next);
 238     }
 239     return 0;
 240 }
 241
 242 const VMStateDescription vmstate_i2c_slave = {
 243     .name = "I2CSlave",
 244     .version_id = 1,
 245     .minimum_version_id = 1,
 246     .post_load = i2c_slave_post_load,
 247     .fields = (VMStateField[]) {
 248         VMSTATE_UINT8(address, I2CSlave),
 249         VMSTATE_END_OF_LIST()
 250     }
 251 };
 252
 253 static int i2c_slave_qdev_init(DeviceState *dev)
 254 {
 255     I2CSlave *s = I2C_SLAVE(dev);
 256     I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(s);
 257
 258     return sc->init(s);
 259 }
 260
 261 DeviceState *i2c_create_slave(I2CBus *bus, const char *name, uint8_t addr)
 262 {
 263     DeviceState *dev;
 264
 265     dev = qdev_create(&bus->qbus, name);
 266     qdev_prop_set_uint8(dev, "address", addr);
 267     qdev_init_nofail(dev);
 268     return dev;
 269 }
 270
 271 static void i2c_slave_class_init(ObjectClass *klass, void *data)
 272 {
 273     DeviceClass *k = DEVICE_CLASS(klass);
 274     k->init = i2c_slave_qdev_init;
 275     set_bit(DEVICE_CATEGORY_MISC, k->categories);
 276     k->bus_type = TYPE_I2C_BUS;
 277     k->props = i2c_props;
 278 }
 279
 280 static const TypeInfo i2c_slave_type_info = {
 281     .name = TYPE_I2C_SLAVE,
 282     .parent = TYPE_DEVICE,
 283     .instance_size = sizeof(I2CSlave),
 284     .abstract = true,
 285     .class_size = sizeof(I2CSlaveClass),
 286     .class_init = i2c_slave_class_init,
 287 };
 288
 289 static void i2c_slave_register_types(void)
 290 {
 291     type_register_static(&i2c_bus_info);
 292     type_register_static(&i2c_slave_type_info);
 293 }
 294
 295 type_init(i2c_slave_register_types)