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 /* TODO: Make this handle multiple masters.  */
  92 /*
  93  * Start or continue an i2c transaction.  When this is called for the
  94  * first time or after an i2c_end_transfer(), if it returns an error
  95  * the bus transaction is terminated (or really never started).  If
  96  * this is called after another i2c_start_transfer() without an
  97  * intervening i2c_end_transfer(), and it returns an error, the
  98  * transaction will not be terminated.  The caller must do it.
  99  *
 100  * This corresponds with the way real hardware works.  The SMBus
 101  * protocol uses a start transfer to switch from write to read mode
 102  * without releasing the bus.  If that fails, the bus is still
 103  * in a transaction.
 104  */
 105 int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
 106 {
 107     BusChild *kid;
 108     I2CSlaveClass *sc;
 109     I2CNode *node;
 110     bool bus_scanned = false;
 111
 112     if (address == I2C_BROADCAST) {
 113         /*
 114          * This is a broadcast, the current_devs will be all the devices of the
 115          * bus.
 116          */
 117         bus->broadcast = true;
 118     }
 119
 120     /*
 121      * If there are already devices in the list, that means we are in
 122      * the middle of a transaction and we shouldn't rescan the bus.
 123      *
 124      * This happens with any SMBus transaction, even on a pure I2C
 125      * device.  The interface does a transaction start without
 126      * terminating the previous transaction.
 127      */
 128     if (QLIST_EMPTY(&bus->current_devs)) {
 129         QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
 130             DeviceState *qdev = kid->child;
 131             I2CSlave *candidate = I2C_SLAVE(qdev);
 132             if ((candidate->address == address) || (bus->broadcast)) {
 133                 node = g_malloc(sizeof(struct I2CNode));
 134                 node->elt = candidate;
 135                 QLIST_INSERT_HEAD(&bus->current_devs, node, next);
 136                 if (!bus->broadcast) {
 137                     break;
 138                 }
 139             }
 140         }
 141         bus_scanned = true;
 142     }
 143
 144     if (QLIST_EMPTY(&bus->current_devs)) {
 145         return 1;
 146     }
 147
 148     QLIST_FOREACH(node, &bus->current_devs, next) {
 149         int rv;
 150
 151         sc = I2C_SLAVE_GET_CLASS(node->elt);
 152         /* If the bus is already busy, assume this is a repeated
 153            start condition.  */
 154
 155         if (sc->event) {
 156             rv = sc->event(node->elt, recv ? I2C_START_RECV : I2C_START_SEND);
 157             if (rv && !bus->broadcast) {
 158                 if (bus_scanned) {
 159                     /* First call, terminate the transfer. */
 160                     i2c_end_transfer(bus);
 161                 }
 162                 return rv;
 163             }
 164         }
 165     }
 166     return 0;
 167 }
 168
 169 void i2c_end_transfer(I2CBus *bus)
 170 {
 171     I2CSlaveClass *sc;
 172     I2CNode *node, *next;
 173
 174     QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) {
 175         sc = I2C_SLAVE_GET_CLASS(node->elt);
 176         if (sc->event) {
 177             sc->event(node->elt, I2C_FINISH);
 178         }
 179         QLIST_REMOVE(node, next);
 180         g_free(node);
 181     }
 182     bus->broadcast = false;
 183 }
 184
 185 int i2c_send_recv(I2CBus *bus, uint8_t *data, bool send)
 186 {
 187     I2CSlaveClass *sc;
 188     I2CNode *node;
 189     int ret = 0;
 190
 191     if (send) {
 192         QLIST_FOREACH(node, &bus->current_devs, next) {
 193             sc = I2C_SLAVE_GET_CLASS(node->elt);
 194             if (sc->send) {
 195                 ret = ret || sc->send(node->elt, *data);
 196             } else {
 197                 ret = -1;
 198             }
 199         }
 200         return ret ? -1 : 0;
 201     } else {
 202         if ((QLIST_EMPTY(&bus->current_devs)) || (bus->broadcast)) {
 203             return -1;
 204         }
 205
 206         sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
 207         if (sc->recv) {
 208             ret = sc->recv(QLIST_FIRST(&bus->current_devs)->elt);
 209             if (ret < 0) {
 210                 return ret;
 211             } else {
 212                 *data = ret;
 213                 return 0;
 214             }
 215         }
 216         return -1;
 217     }
 218 }
 219
 220 int i2c_send(I2CBus *bus, uint8_t data)
 221 {
 222     return i2c_send_recv(bus, &data, true);
 223 }
 224
 225 int i2c_recv(I2CBus *bus)
 226 {
 227     uint8_t data;
 228     int ret = i2c_send_recv(bus, &data, false);
 229
 230     return ret < 0 ? ret : data;
 231 }
 232
 233 void i2c_nack(I2CBus *bus)
 234 {
 235     I2CSlaveClass *sc;
 236     I2CNode *node;
 237
 238     if (QLIST_EMPTY(&bus->current_devs)) {
 239         return;
 240     }
 241
 242     QLIST_FOREACH(node, &bus->current_devs, next) {
 243         sc = I2C_SLAVE_GET_CLASS(node->elt);
 244         if (sc->event) {
 245             sc->event(node->elt, I2C_NACK);
 246         }
 247     }
 248 }
 249
 250 static int i2c_slave_post_load(void *opaque, int version_id)
 251 {
 252     I2CSlave *dev = opaque;
 253     I2CBus *bus;
 254     I2CNode *node;
 255
 256     bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev)));
 257     if ((bus->saved_address == dev->address) ||
 258         (bus->saved_address == I2C_BROADCAST)) {
 259         node = g_malloc(sizeof(struct I2CNode));
 260         node->elt = dev;
 261         QLIST_INSERT_HEAD(&bus->current_devs, node, next);
 262     }
 263     return 0;
 264 }
 265
 266 const VMStateDescription vmstate_i2c_slave = {
 267     .name = "I2CSlave",
 268     .version_id = 1,
 269     .minimum_version_id = 1,
 270     .post_load = i2c_slave_post_load,
 271     .fields = (VMStateField[]) {
 272         VMSTATE_UINT8(address, I2CSlave),
 273         VMSTATE_END_OF_LIST()
 274     }
 275 };
 276
 277 static int i2c_slave_qdev_init(DeviceState *dev)
 278 {
 279     I2CSlave *s = I2C_SLAVE(dev);
 280     I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(s);
 281
 282     if (sc->init) {
 283         return sc->init(s);
 284     }
 285
 286     return 0;
 287 }
 288
 289 DeviceState *i2c_create_slave(I2CBus *bus, const char *name, uint8_t addr)
 290 {
 291     DeviceState *dev;
 292
 293     dev = qdev_create(&bus->qbus, name);
 294     qdev_prop_set_uint8(dev, "address", addr);
 295     qdev_init_nofail(dev);
 296     return dev;
 297 }
 298
 299 static void i2c_slave_class_init(ObjectClass *klass, void *data)
 300 {
 301     DeviceClass *k = DEVICE_CLASS(klass);
 302     k->init = i2c_slave_qdev_init;
 303     set_bit(DEVICE_CATEGORY_MISC, k->categories);
 304     k->bus_type = TYPE_I2C_BUS;
 305     k->props = i2c_props;
 306 }
 307
 308 static const TypeInfo i2c_slave_type_info = {
 309     .name = TYPE_I2C_SLAVE,
 310     .parent = TYPE_DEVICE,
 311     .instance_size = sizeof(I2CSlave),
 312     .abstract = true,
 313     .class_size = sizeof(I2CSlaveClass),
 314     .class_init = i2c_slave_class_init,
 315 };
 316
 317 static void i2c_slave_register_types(void)
 318 {
 319     type_register_static(&i2c_bus_info);
 320     type_register_static(&i2c_slave_type_info);
 321 }
 322
 323 type_init(i2c_slave_register_types)