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     BusState qbus;
  24     QLIST_HEAD(, I2CNode) current_devs;
  25     uint8_t saved_address;
  26     bool broadcast;
  27 };
  28
  29 static Property i2c_props[] = {
  30     DEFINE_PROP_UINT8("address", struct I2CSlave, address, 0),
  31     DEFINE_PROP_END_OF_LIST(),
  32 };
  33
  34 #define TYPE_I2C_BUS "i2c-bus"
  35 #define I2C_BUS(obj) OBJECT_CHECK(I2CBus, (obj), TYPE_I2C_BUS)
  36
  37 static const TypeInfo i2c_bus_info = {
  38     .name = TYPE_I2C_BUS,
  39     .parent = TYPE_BUS,
  40     .instance_size = sizeof(I2CBus),
  41 };
  42
  43 static int i2c_bus_pre_save(void *opaque)
  44 {
  45     I2CBus *bus = opaque;
  46
  47     bus->saved_address = -1;
  48     if (!QLIST_EMPTY(&bus->current_devs)) {
  49         if (!bus->broadcast) {
  50             bus->saved_address = QLIST_FIRST(&bus->current_devs)->elt->address;
  51         } else {
  52             bus->saved_address = I2C_BROADCAST;
  53         }
  54     }
  55
  56     return 0;
  57 }
  58
  59 static const VMStateDescription vmstate_i2c_bus = {
  60     .name = "i2c_bus",
  61     .version_id = 1,
  62     .minimum_version_id = 1,
  63     .pre_save = i2c_bus_pre_save,
  64     .fields = (VMStateField[]) {
  65         VMSTATE_UINT8(saved_address, I2CBus),
  66         VMSTATE_END_OF_LIST()
  67     }
  68 };
  69
  70 /* Create a new I2C bus.  */
  71 I2CBus *i2c_init_bus(DeviceState *parent, const char *name)
  72 {
  73     I2CBus *bus;
  74
  75     bus = I2C_BUS(qbus_create(TYPE_I2C_BUS, parent, name));
  76     QLIST_INIT(&bus->current_devs);
  77     vmstate_register(NULL, -1, &vmstate_i2c_bus, bus);
  78     return bus;
  79 }
  80
  81 void i2c_set_slave_address(I2CSlave *dev, uint8_t address)
  82 {
  83     dev->address = address;
  84 }
  85
  86 /* Return nonzero if bus is busy.  */
  87 int i2c_bus_busy(I2CBus *bus)
  88 {
  89     return !QLIST_EMPTY(&bus->current_devs);
  90 }
  91
  92 /* TODO: Make this handle multiple masters.  */
  93 /*
  94  * Start or continue an i2c transaction.  When this is called for the
  95  * first time or after an i2c_end_transfer(), if it returns an error
  96  * the bus transaction is terminated (or really never started).  If
  97  * this is called after another i2c_start_transfer() without an
  98  * intervening i2c_end_transfer(), and it returns an error, the
  99  * transaction will not be terminated.  The caller must do it.
 100  *
 101  * This corresponds with the way real hardware works.  The SMBus
 102  * protocol uses a start transfer to switch from write to read mode
 103  * without releasing the bus.  If that fails, the bus is still
 104  * in a transaction.
 105  */
 106 int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
 107 {
 108     BusChild *kid;
 109     I2CSlaveClass *sc;
 110     I2CNode *node;
 111     bool bus_scanned = false;
 112
 113     if (address == I2C_BROADCAST) {
 114         /*
 115          * This is a broadcast, the current_devs will be all the devices of the
 116          * bus.
 117          */
 118         bus->broadcast = true;
 119     }
 120
 121     /*
 122      * If there are already devices in the list, that means we are in
 123      * the middle of a transaction and we shouldn't rescan the bus.
 124      *
 125      * This happens with any SMBus transaction, even on a pure I2C
 126      * device.  The interface does a transaction start without
 127      * terminating the previous transaction.
 128      */
 129     if (QLIST_EMPTY(&bus->current_devs)) {
 130         QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
 131             DeviceState *qdev = kid->child;
 132             I2CSlave *candidate = I2C_SLAVE(qdev);
 133             if ((candidate->address == address) || (bus->broadcast)) {
 134                 node = g_malloc(sizeof(struct I2CNode));
 135                 node->elt = candidate;
 136                 QLIST_INSERT_HEAD(&bus->current_devs, node, next);
 137                 if (!bus->broadcast) {
 138                     break;
 139                 }
 140             }
 141         }
 142         bus_scanned = true;
 143     }
 144
 145     if (QLIST_EMPTY(&bus->current_devs)) {
 146         return 1;
 147     }
 148
 149     QLIST_FOREACH(node, &bus->current_devs, next) {
 150         int rv;
 151
 152         sc = I2C_SLAVE_GET_CLASS(node->elt);
 153         /* If the bus is already busy, assume this is a repeated
 154            start condition.  */
 155
 156         if (sc->event) {
 157             rv = sc->event(node->elt, recv ? I2C_START_RECV : I2C_START_SEND);
 158             if (rv && !bus->broadcast) {
 159                 if (bus_scanned) {
 160                     /* First call, terminate the transfer. */
 161                     i2c_end_transfer(bus);
 162                 }
 163                 return rv;
 164             }
 165         }
 166     }
 167     return 0;
 168 }
 169
 170 void i2c_end_transfer(I2CBus *bus)
 171 {
 172     I2CSlaveClass *sc;
 173     I2CNode *node, *next;
 174
 175     QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) {
 176         sc = I2C_SLAVE_GET_CLASS(node->elt);
 177         if (sc->event) {
 178             sc->event(node->elt, I2C_FINISH);
 179         }
 180         QLIST_REMOVE(node, next);
 181         g_free(node);
 182     }
 183     bus->broadcast = false;
 184 }
 185
 186 int i2c_send_recv(I2CBus *bus, uint8_t *data, bool send)
 187 {
 188     I2CSlaveClass *sc;
 189     I2CNode *node;
 190     int ret = 0;
 191
 192     if (send) {
 193         QLIST_FOREACH(node, &bus->current_devs, next) {
 194             sc = I2C_SLAVE_GET_CLASS(node->elt);
 195             if (sc->send) {
 196                 ret = ret || sc->send(node->elt, *data);
 197             } else {
 198                 ret = -1;
 199             }
 200         }
 201         return ret ? -1 : 0;
 202     } else {
 203         if ((QLIST_EMPTY(&bus->current_devs)) || (bus->broadcast)) {
 204             return -1;
 205         }
 206
 207         sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
 208         if (sc->recv) {
 209             ret = sc->recv(QLIST_FIRST(&bus->current_devs)->elt);
 210             if (ret < 0) {
 211                 return ret;
 212             } else {
 213                 *data = ret;
 214                 return 0;
 215             }
 216         }
 217         return -1;
 218     }
 219 }
 220
 221 int i2c_send(I2CBus *bus, uint8_t data)
 222 {
 223     return i2c_send_recv(bus, &data, true);
 224 }
 225
 226 int i2c_recv(I2CBus *bus)
 227 {
 228     uint8_t data;
 229     int ret = i2c_send_recv(bus, &data, false);
 230
 231     return ret < 0 ? ret : data;
 232 }
 233
 234 void i2c_nack(I2CBus *bus)
 235 {
 236     I2CSlaveClass *sc;
 237     I2CNode *node;
 238
 239     if (QLIST_EMPTY(&bus->current_devs)) {
 240         return;
 241     }
 242
 243     QLIST_FOREACH(node, &bus->current_devs, next) {
 244         sc = I2C_SLAVE_GET_CLASS(node->elt);
 245         if (sc->event) {
 246             sc->event(node->elt, I2C_NACK);
 247         }
 248     }
 249 }
 250
 251 static int i2c_slave_post_load(void *opaque, int version_id)
 252 {
 253     I2CSlave *dev = opaque;
 254     I2CBus *bus;
 255     I2CNode *node;
 256
 257     bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev)));
 258     if ((bus->saved_address == dev->address) ||
 259         (bus->saved_address == I2C_BROADCAST)) {
 260         node = g_malloc(sizeof(struct I2CNode));
 261         node->elt = dev;
 262         QLIST_INSERT_HEAD(&bus->current_devs, node, next);
 263     }
 264     return 0;
 265 }
 266
 267 const VMStateDescription vmstate_i2c_slave = {
 268     .name = "I2CSlave",
 269     .version_id = 1,
 270     .minimum_version_id = 1,
 271     .post_load = i2c_slave_post_load,
 272     .fields = (VMStateField[]) {
 273         VMSTATE_UINT8(address, I2CSlave),
 274         VMSTATE_END_OF_LIST()
 275     }
 276 };
 277
 278 static int i2c_slave_qdev_init(DeviceState *dev)
 279 {
 280     I2CSlave *s = I2C_SLAVE(dev);
 281     I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(s);
 282
 283     if (sc->init) {
 284         return sc->init(s);
 285     }
 286
 287     return 0;
 288 }
 289
 290 DeviceState *i2c_create_slave(I2CBus *bus, const char *name, uint8_t addr)
 291 {
 292     DeviceState *dev;
 293
 294     dev = qdev_create(&bus->qbus, name);
 295     qdev_prop_set_uint8(dev, "address", addr);
 296     qdev_init_nofail(dev);
 297     return dev;
 298 }
 299
 300 static void i2c_slave_class_init(ObjectClass *klass, void *data)
 301 {
 302     DeviceClass *k = DEVICE_CLASS(klass);
 303     k->init = i2c_slave_qdev_init;
 304     set_bit(DEVICE_CATEGORY_MISC, k->categories);
 305     k->bus_type = TYPE_I2C_BUS;
 306     k->props = i2c_props;
 307 }
 308
 309 static const TypeInfo i2c_slave_type_info = {
 310     .name = TYPE_I2C_SLAVE,
 311     .parent = TYPE_DEVICE,
 312     .instance_size = sizeof(I2CSlave),
 313     .abstract = true,
 314     .class_size = sizeof(I2CSlaveClass),
 315     .class_init = i2c_slave_class_init,
 316 };
 317
 318 static void i2c_slave_register_types(void)
 319 {
 320     type_register_static(&i2c_bus_info);
 321     type_register_static(&i2c_slave_type_info);
 322 }
 323
 324 type_init(i2c_slave_register_types)