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 #include "hw/qdev-properties.h"
  13 #include "migration/vmstate.h"
  14 #include "qapi/error.h"
  15 #include "qemu/module.h"
  16 #include "trace.h"
  17
  18 #define I2C_BROADCAST 0x00
  19
  20 static Property i2c_props[] = {
  21     DEFINE_PROP_UINT8("address", struct I2CSlave, address, 0),
  22     DEFINE_PROP_END_OF_LIST(),
  23 };
  24
  25 static const TypeInfo i2c_bus_info = {
  26     .name = TYPE_I2C_BUS,
  27     .parent = TYPE_BUS,
  28     .instance_size = sizeof(I2CBus),
  29 };
  30
  31 static int i2c_bus_pre_save(void *opaque)
  32 {
  33     I2CBus *bus = opaque;
  34
  35     bus->saved_address = -1;
  36     if (!QLIST_EMPTY(&bus->current_devs)) {
  37         if (!bus->broadcast) {
  38             bus->saved_address = QLIST_FIRST(&bus->current_devs)->elt->address;
  39         } else {
  40             bus->saved_address = I2C_BROADCAST;
  41         }
  42     }
  43
  44     return 0;
  45 }
  46
  47 static const VMStateDescription vmstate_i2c_bus = {
  48     .name = "i2c_bus",
  49     .version_id = 1,
  50     .minimum_version_id = 1,
  51     .pre_save = i2c_bus_pre_save,
  52     .fields = (VMStateField[]) {
  53         VMSTATE_UINT8(saved_address, I2CBus),
  54         VMSTATE_END_OF_LIST()
  55     }
  56 };
  57
  58 /* Create a new I2C bus.  */
  59 I2CBus *i2c_init_bus(DeviceState *parent, const char *name)
  60 {
  61     I2CBus *bus;
  62
  63     bus = I2C_BUS(qbus_create(TYPE_I2C_BUS, parent, name));
  64     QLIST_INIT(&bus->current_devs);
  65     vmstate_register(NULL, VMSTATE_INSTANCE_ID_ANY, &vmstate_i2c_bus, bus);
  66     return bus;
  67 }
  68
  69 void i2c_set_slave_address(I2CSlave *dev, uint8_t address)
  70 {
  71     dev->address = address;
  72 }
  73
  74 /* Return nonzero if bus is busy.  */
  75 int i2c_bus_busy(I2CBus *bus)
  76 {
  77     return !QLIST_EMPTY(&bus->current_devs);
  78 }
  79
  80 bool i2c_scan_bus(I2CBus *bus, uint8_t address, bool broadcast,
  81                   I2CNodeList *current_devs)
  82 {
  83     BusChild *kid;
  84
  85     QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
  86         DeviceState *qdev = kid->child;
  87         I2CSlave *candidate = I2C_SLAVE(qdev);
  88         I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(candidate);
  89
  90         if (sc->match_and_add(candidate, address, broadcast, current_devs)) {
  91             if (!broadcast) {
  92                 return true;
  93             }
  94         }
  95     }
  96
  97     /*
  98      * If broadcast was true, and the list was full or empty, return true. If
  99      * broadcast was false, return false.
 100      */
 101     return broadcast;
 102 }
 103
 104 /* TODO: Make this handle multiple masters.  */
 105 /*
 106  * Start or continue an i2c transaction.  When this is called for the
 107  * first time or after an i2c_end_transfer(), if it returns an error
 108  * the bus transaction is terminated (or really never started).  If
 109  * this is called after another i2c_start_transfer() without an
 110  * intervening i2c_end_transfer(), and it returns an error, the
 111  * transaction will not be terminated.  The caller must do it.
 112  *
 113  * This corresponds with the way real hardware works.  The SMBus
 114  * protocol uses a start transfer to switch from write to read mode
 115  * without releasing the bus.  If that fails, the bus is still
 116  * in a transaction.
 117  */
 118 int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
 119 {
 120     I2CSlaveClass *sc;
 121     I2CNode *node;
 122     bool bus_scanned = false;
 123
 124     if (address == I2C_BROADCAST) {
 125         /*
 126          * This is a broadcast, the current_devs will be all the devices of the
 127          * bus.
 128          */
 129         bus->broadcast = true;
 130     }
 131
 132     /*
 133      * If there are already devices in the list, that means we are in
 134      * the middle of a transaction and we shouldn't rescan the bus.
 135      *
 136      * This happens with any SMBus transaction, even on a pure I2C
 137      * device.  The interface does a transaction start without
 138      * terminating the previous transaction.
 139      */
 140     if (QLIST_EMPTY(&bus->current_devs)) {
 141         /* Disregard whether devices were found. */
 142         (void)i2c_scan_bus(bus, address, bus->broadcast, &bus->current_devs);
 143         bus_scanned = true;
 144     }
 145
 146     if (QLIST_EMPTY(&bus->current_devs)) {
 147         return 1;
 148     }
 149
 150     QLIST_FOREACH(node, &bus->current_devs, next) {
 151         I2CSlave *s = node->elt;
 152         int rv;
 153
 154         sc = I2C_SLAVE_GET_CLASS(s);
 155         /* If the bus is already busy, assume this is a repeated
 156            start condition.  */
 157
 158         if (sc->event) {
 159             trace_i2c_event("start", s->address);
 160             rv = sc->event(s, recv ? I2C_START_RECV : I2C_START_SEND);
 161             if (rv && !bus->broadcast) {
 162                 if (bus_scanned) {
 163                     /* First call, terminate the transfer. */
 164                     i2c_end_transfer(bus);
 165                 }
 166                 return rv;
 167             }
 168         }
 169     }
 170     return 0;
 171 }
 172
 173 void i2c_end_transfer(I2CBus *bus)
 174 {
 175     I2CSlaveClass *sc;
 176     I2CNode *node, *next;
 177
 178     QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) {
 179         I2CSlave *s = node->elt;
 180         sc = I2C_SLAVE_GET_CLASS(s);
 181         if (sc->event) {
 182             trace_i2c_event("finish", s->address);
 183             sc->event(s, I2C_FINISH);
 184         }
 185         QLIST_REMOVE(node, next);
 186         g_free(node);
 187     }
 188     bus->broadcast = false;
 189 }
 190
 191 int i2c_send_recv(I2CBus *bus, uint8_t *data, bool send)
 192 {
 193     I2CSlaveClass *sc;
 194     I2CSlave *s;
 195     I2CNode *node;
 196     int ret = 0;
 197
 198     if (send) {
 199         QLIST_FOREACH(node, &bus->current_devs, next) {
 200             s = node->elt;
 201             sc = I2C_SLAVE_GET_CLASS(s);
 202             if (sc->send) {
 203                 trace_i2c_send(s->address, *data);
 204                 ret = ret || sc->send(s, *data);
 205             } else {
 206                 ret = -1;
 207             }
 208         }
 209         return ret ? -1 : 0;
 210     } else {
 211         ret = 0xff;
 212         if (!QLIST_EMPTY(&bus->current_devs) && !bus->broadcast) {
 213             sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
 214             if (sc->recv) {
 215                 s = QLIST_FIRST(&bus->current_devs)->elt;
 216                 ret = sc->recv(s);
 217                 trace_i2c_recv(s->address, ret);
 218             }
 219         }
 220         *data = ret;
 221         return 0;
 222     }
 223 }
 224
 225 int i2c_send(I2CBus *bus, uint8_t data)
 226 {
 227     return i2c_send_recv(bus, &data, true);
 228 }
 229
 230 uint8_t i2c_recv(I2CBus *bus)
 231 {
 232     uint8_t data = 0xff;
 233
 234     i2c_send_recv(bus, &data, false);
 235     return data;
 236 }
 237
 238 void i2c_nack(I2CBus *bus)
 239 {
 240     I2CSlaveClass *sc;
 241     I2CNode *node;
 242
 243     if (QLIST_EMPTY(&bus->current_devs)) {
 244         return;
 245     }
 246
 247     QLIST_FOREACH(node, &bus->current_devs, next) {
 248         sc = I2C_SLAVE_GET_CLASS(node->elt);
 249         if (sc->event) {
 250             trace_i2c_event("nack", node->elt->address);
 251             sc->event(node->elt, I2C_NACK);
 252         }
 253     }
 254 }
 255
 256 static int i2c_slave_post_load(void *opaque, int version_id)
 257 {
 258     I2CSlave *dev = opaque;
 259     I2CBus *bus;
 260     I2CNode *node;
 261
 262     bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev)));
 263     if ((bus->saved_address == dev->address) ||
 264         (bus->saved_address == I2C_BROADCAST)) {
 265         node = g_malloc(sizeof(struct I2CNode));
 266         node->elt = dev;
 267         QLIST_INSERT_HEAD(&bus->current_devs, node, next);
 268     }
 269     return 0;
 270 }
 271
 272 const VMStateDescription vmstate_i2c_slave = {
 273     .name = "I2CSlave",
 274     .version_id = 1,
 275     .minimum_version_id = 1,
 276     .post_load = i2c_slave_post_load,
 277     .fields = (VMStateField[]) {
 278         VMSTATE_UINT8(address, I2CSlave),
 279         VMSTATE_END_OF_LIST()
 280     }
 281 };
 282
 283 I2CSlave *i2c_slave_new(const char *name, uint8_t addr)
 284 {
 285     DeviceState *dev;
 286
 287     dev = qdev_new(name);
 288     qdev_prop_set_uint8(dev, "address", addr);
 289     return I2C_SLAVE(dev);
 290 }
 291
 292 bool i2c_slave_realize_and_unref(I2CSlave *dev, I2CBus *bus, Error **errp)
 293 {
 294     return qdev_realize_and_unref(&dev->qdev, &bus->qbus, errp);
 295 }
 296
 297 I2CSlave *i2c_slave_create_simple(I2CBus *bus, const char *name, uint8_t addr)
 298 {
 299     I2CSlave *dev = i2c_slave_new(name, addr);
 300
 301     i2c_slave_realize_and_unref(dev, bus, &error_abort);
 302
 303     return dev;
 304 }
 305
 306 static bool i2c_slave_match(I2CSlave *candidate, uint8_t address,
 307                             bool broadcast, I2CNodeList *current_devs)
 308 {
 309     if ((candidate->address == address) || (broadcast)) {
 310         I2CNode *node = g_malloc(sizeof(struct I2CNode));
 311         node->elt = candidate;
 312         QLIST_INSERT_HEAD(current_devs, node, next);
 313         return true;
 314     }
 315
 316     /* Not found and not broadcast. */
 317     return false;
 318 }
 319
 320 static void i2c_slave_class_init(ObjectClass *klass, void *data)
 321 {
 322     DeviceClass *k = DEVICE_CLASS(klass);
 323     I2CSlaveClass *sc = I2C_SLAVE_CLASS(klass);
 324     set_bit(DEVICE_CATEGORY_MISC, k->categories);
 325     k->bus_type = TYPE_I2C_BUS;
 326     device_class_set_props(k, i2c_props);
 327     sc->match_and_add = i2c_slave_match;
 328 }
 329
 330 static const TypeInfo i2c_slave_type_info = {
 331     .name = TYPE_I2C_SLAVE,
 332     .parent = TYPE_DEVICE,
 333     .instance_size = sizeof(I2CSlave),
 334     .abstract = true,
 335     .class_size = sizeof(I2CSlaveClass),
 336     .class_init = i2c_slave_class_init,
 337 };
 338
 339 static void i2c_slave_register_types(void)
 340 {
 341     type_register_static(&i2c_bus_info);
 342     type_register_static(&i2c_slave_type_info);
 343 }
 344
 345 type_init(i2c_slave_register_types)