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_slave_set_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  * @event must be I2C_START_RECV or I2C_START_SEND.
 119  */
 120 static int i2c_do_start_transfer(I2CBus *bus, uint8_t address,
 121                                  enum i2c_event event)
 122 {
 123     I2CSlaveClass *sc;
 124     I2CNode *node;
 125     bool bus_scanned = false;
 126
 127     if (address == I2C_BROADCAST) {
 128         /*
 129          * This is a broadcast, the current_devs will be all the devices of the
 130          * bus.
 131          */
 132         bus->broadcast = true;
 133     }
 134
 135     /*
 136      * If there are already devices in the list, that means we are in
 137      * the middle of a transaction and we shouldn't rescan the bus.
 138      *
 139      * This happens with any SMBus transaction, even on a pure I2C
 140      * device.  The interface does a transaction start without
 141      * terminating the previous transaction.
 142      */
 143     if (QLIST_EMPTY(&bus->current_devs)) {
 144         /* Disregard whether devices were found. */
 145         (void)i2c_scan_bus(bus, address, bus->broadcast, &bus->current_devs);
 146         bus_scanned = true;
 147     }
 148
 149     if (QLIST_EMPTY(&bus->current_devs)) {
 150         return 1;
 151     }
 152
 153     QLIST_FOREACH(node, &bus->current_devs, next) {
 154         I2CSlave *s = node->elt;
 155         int rv;
 156
 157         sc = I2C_SLAVE_GET_CLASS(s);
 158         /* If the bus is already busy, assume this is a repeated
 159            start condition.  */
 160
 161         if (sc->event) {
 162             trace_i2c_event("start", s->address);
 163             rv = sc->event(s, event);
 164             if (rv && !bus->broadcast) {
 165                 if (bus_scanned) {
 166                     /* First call, terminate the transfer. */
 167                     i2c_end_transfer(bus);
 168                 }
 169                 return rv;
 170             }
 171         }
 172     }
 173     return 0;
 174 }
 175
 176 int i2c_start_transfer(I2CBus *bus, uint8_t address, bool is_recv)
 177 {
 178     return i2c_do_start_transfer(bus, address, is_recv
 179                                                ? I2C_START_RECV
 180                                                : I2C_START_SEND);
 181 }
 182
 183 int i2c_start_recv(I2CBus *bus, uint8_t address)
 184 {
 185     return i2c_do_start_transfer(bus, address, I2C_START_RECV);
 186 }
 187
 188 int i2c_start_send(I2CBus *bus, uint8_t address)
 189 {
 190     return i2c_do_start_transfer(bus, address, I2C_START_SEND);
 191 }
 192
 193 void i2c_end_transfer(I2CBus *bus)
 194 {
 195     I2CSlaveClass *sc;
 196     I2CNode *node, *next;
 197
 198     QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) {
 199         I2CSlave *s = node->elt;
 200         sc = I2C_SLAVE_GET_CLASS(s);
 201         if (sc->event) {
 202             trace_i2c_event("finish", s->address);
 203             sc->event(s, I2C_FINISH);
 204         }
 205         QLIST_REMOVE(node, next);
 206         g_free(node);
 207     }
 208     bus->broadcast = false;
 209 }
 210
 211 int i2c_send(I2CBus *bus, uint8_t data)
 212 {
 213     I2CSlaveClass *sc;
 214     I2CSlave *s;
 215     I2CNode *node;
 216     int ret = 0;
 217
 218     QLIST_FOREACH(node, &bus->current_devs, next) {
 219         s = node->elt;
 220         sc = I2C_SLAVE_GET_CLASS(s);
 221         if (sc->send) {
 222             trace_i2c_send(s->address, data);
 223             ret = ret || sc->send(s, data);
 224         } else {
 225             ret = -1;
 226         }
 227     }
 228
 229     return ret ? -1 : 0;
 230 }
 231
 232 uint8_t i2c_recv(I2CBus *bus)
 233 {
 234     uint8_t data = 0xff;
 235     I2CSlaveClass *sc;
 236     I2CSlave *s;
 237
 238     if (!QLIST_EMPTY(&bus->current_devs) && !bus->broadcast) {
 239         sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
 240         if (sc->recv) {
 241             s = QLIST_FIRST(&bus->current_devs)->elt;
 242             data = sc->recv(s);
 243             trace_i2c_recv(s->address, data);
 244         }
 245     }
 246
 247     return data;
 248 }
 249
 250 void i2c_nack(I2CBus *bus)
 251 {
 252     I2CSlaveClass *sc;
 253     I2CNode *node;
 254
 255     if (QLIST_EMPTY(&bus->current_devs)) {
 256         return;
 257     }
 258
 259     QLIST_FOREACH(node, &bus->current_devs, next) {
 260         sc = I2C_SLAVE_GET_CLASS(node->elt);
 261         if (sc->event) {
 262             trace_i2c_event("nack", node->elt->address);
 263             sc->event(node->elt, I2C_NACK);
 264         }
 265     }
 266 }
 267
 268 static int i2c_slave_post_load(void *opaque, int version_id)
 269 {
 270     I2CSlave *dev = opaque;
 271     I2CBus *bus;
 272     I2CNode *node;
 273
 274     bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev)));
 275     if ((bus->saved_address == dev->address) ||
 276         (bus->saved_address == I2C_BROADCAST)) {
 277         node = g_malloc(sizeof(struct I2CNode));
 278         node->elt = dev;
 279         QLIST_INSERT_HEAD(&bus->current_devs, node, next);
 280     }
 281     return 0;
 282 }
 283
 284 const VMStateDescription vmstate_i2c_slave = {
 285     .name = "I2CSlave",
 286     .version_id = 1,
 287     .minimum_version_id = 1,
 288     .post_load = i2c_slave_post_load,
 289     .fields = (VMStateField[]) {
 290         VMSTATE_UINT8(address, I2CSlave),
 291         VMSTATE_END_OF_LIST()
 292     }
 293 };
 294
 295 I2CSlave *i2c_slave_new(const char *name, uint8_t addr)
 296 {
 297     DeviceState *dev;
 298
 299     dev = qdev_new(name);
 300     qdev_prop_set_uint8(dev, "address", addr);
 301     return I2C_SLAVE(dev);
 302 }
 303
 304 bool i2c_slave_realize_and_unref(I2CSlave *dev, I2CBus *bus, Error **errp)
 305 {
 306     return qdev_realize_and_unref(&dev->qdev, &bus->qbus, errp);
 307 }
 308
 309 I2CSlave *i2c_slave_create_simple(I2CBus *bus, const char *name, uint8_t addr)
 310 {
 311     I2CSlave *dev = i2c_slave_new(name, addr);
 312
 313     i2c_slave_realize_and_unref(dev, bus, &error_abort);
 314
 315     return dev;
 316 }
 317
 318 static bool i2c_slave_match(I2CSlave *candidate, uint8_t address,
 319                             bool broadcast, I2CNodeList *current_devs)
 320 {
 321     if ((candidate->address == address) || (broadcast)) {
 322         I2CNode *node = g_malloc(sizeof(struct I2CNode));
 323         node->elt = candidate;
 324         QLIST_INSERT_HEAD(current_devs, node, next);
 325         return true;
 326     }
 327
 328     /* Not found and not broadcast. */
 329     return false;
 330 }
 331
 332 static void i2c_slave_class_init(ObjectClass *klass, void *data)
 333 {
 334     DeviceClass *k = DEVICE_CLASS(klass);
 335     I2CSlaveClass *sc = I2C_SLAVE_CLASS(klass);
 336     set_bit(DEVICE_CATEGORY_MISC, k->categories);
 337     k->bus_type = TYPE_I2C_BUS;
 338     device_class_set_props(k, i2c_props);
 339     sc->match_and_add = i2c_slave_match;
 340 }
 341
 342 static const TypeInfo i2c_slave_type_info = {
 343     .name = TYPE_I2C_SLAVE,
 344     .parent = TYPE_DEVICE,
 345     .instance_size = sizeof(I2CSlave),
 346     .abstract = true,
 347     .class_size = sizeof(I2CSlaveClass),
 348     .class_init = i2c_slave_class_init,
 349 };
 350
 351 static void i2c_slave_register_types(void)
 352 {
 353     type_register_static(&i2c_bus_info);
 354     type_register_static(&i2c_slave_type_info);
 355 }
 356
 357 type_init(i2c_slave_register_types)