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 "trace.h"
  13
  14 #define I2C_BROADCAST 0x00
  15
  16 static Property i2c_props[] = {
  17     DEFINE_PROP_UINT8("address", struct I2CSlave, address, 0),
  18     DEFINE_PROP_END_OF_LIST(),
  19 };
  20
  21 static const TypeInfo i2c_bus_info = {
  22     .name = TYPE_I2C_BUS,
  23     .parent = TYPE_BUS,
  24     .instance_size = sizeof(I2CBus),
  25 };
  26
  27 static int i2c_bus_pre_save(void *opaque)
  28 {
  29     I2CBus *bus = opaque;
  30
  31     bus->saved_address = -1;
  32     if (!QLIST_EMPTY(&bus->current_devs)) {
  33         if (!bus->broadcast) {
  34             bus->saved_address = QLIST_FIRST(&bus->current_devs)->elt->address;
  35         } else {
  36             bus->saved_address = I2C_BROADCAST;
  37         }
  38     }
  39
  40     return 0;
  41 }
  42
  43 static const VMStateDescription vmstate_i2c_bus = {
  44     .name = "i2c_bus",
  45     .version_id = 1,
  46     .minimum_version_id = 1,
  47     .pre_save = i2c_bus_pre_save,
  48     .fields = (VMStateField[]) {
  49         VMSTATE_UINT8(saved_address, I2CBus),
  50         VMSTATE_END_OF_LIST()
  51     }
  52 };
  53
  54 /* Create a new I2C bus.  */
  55 I2CBus *i2c_init_bus(DeviceState *parent, const char *name)
  56 {
  57     I2CBus *bus;
  58
  59     bus = I2C_BUS(qbus_create(TYPE_I2C_BUS, parent, name));
  60     QLIST_INIT(&bus->current_devs);
  61     vmstate_register(NULL, -1, &vmstate_i2c_bus, bus);
  62     return bus;
  63 }
  64
  65 void i2c_set_slave_address(I2CSlave *dev, uint8_t address)
  66 {
  67     dev->address = address;
  68 }
  69
  70 /* Return nonzero if bus is busy.  */
  71 int i2c_bus_busy(I2CBus *bus)
  72 {
  73     return !QLIST_EMPTY(&bus->current_devs);
  74 }
  75
  76 /* TODO: Make this handle multiple masters.  */
  77 /*
  78  * Start or continue an i2c transaction.  When this is called for the
  79  * first time or after an i2c_end_transfer(), if it returns an error
  80  * the bus transaction is terminated (or really never started).  If
  81  * this is called after another i2c_start_transfer() without an
  82  * intervening i2c_end_transfer(), and it returns an error, the
  83  * transaction will not be terminated.  The caller must do it.
  84  *
  85  * This corresponds with the way real hardware works.  The SMBus
  86  * protocol uses a start transfer to switch from write to read mode
  87  * without releasing the bus.  If that fails, the bus is still
  88  * in a transaction.
  89  */
  90 int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
  91 {
  92     BusChild *kid;
  93     I2CSlaveClass *sc;
  94     I2CNode *node;
  95     bool bus_scanned = false;
  96
  97     if (address == I2C_BROADCAST) {
  98         /*
  99          * This is a broadcast, the current_devs will be all the devices of the
 100          * bus.
 101          */
 102         bus->broadcast = true;
 103     }
 104
 105     /*
 106      * If there are already devices in the list, that means we are in
 107      * the middle of a transaction and we shouldn't rescan the bus.
 108      *
 109      * This happens with any SMBus transaction, even on a pure I2C
 110      * device.  The interface does a transaction start without
 111      * terminating the previous transaction.
 112      */
 113     if (QLIST_EMPTY(&bus->current_devs)) {
 114         QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
 115             DeviceState *qdev = kid->child;
 116             I2CSlave *candidate = I2C_SLAVE(qdev);
 117             if ((candidate->address == address) || (bus->broadcast)) {
 118                 node = g_malloc(sizeof(struct I2CNode));
 119                 node->elt = candidate;
 120                 QLIST_INSERT_HEAD(&bus->current_devs, node, next);
 121                 if (!bus->broadcast) {
 122                     break;
 123                 }
 124             }
 125         }
 126         bus_scanned = true;
 127     }
 128
 129     if (QLIST_EMPTY(&bus->current_devs)) {
 130         return 1;
 131     }
 132
 133     QLIST_FOREACH(node, &bus->current_devs, next) {
 134         I2CSlave *s = node->elt;
 135         int rv;
 136
 137         sc = I2C_SLAVE_GET_CLASS(s);
 138         /* If the bus is already busy, assume this is a repeated
 139            start condition.  */
 140
 141         if (sc->event) {
 142             trace_i2c_event("start", s->address);
 143             rv = sc->event(s, recv ? I2C_START_RECV : I2C_START_SEND);
 144             if (rv && !bus->broadcast) {
 145                 if (bus_scanned) {
 146                     /* First call, terminate the transfer. */
 147                     i2c_end_transfer(bus);
 148                 }
 149                 return rv;
 150             }
 151         }
 152     }
 153     return 0;
 154 }
 155
 156 void i2c_end_transfer(I2CBus *bus)
 157 {
 158     I2CSlaveClass *sc;
 159     I2CNode *node, *next;
 160
 161     QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) {
 162         I2CSlave *s = node->elt;
 163         sc = I2C_SLAVE_GET_CLASS(s);
 164         if (sc->event) {
 165             trace_i2c_event("finish", s->address);
 166             sc->event(s, I2C_FINISH);
 167         }
 168         QLIST_REMOVE(node, next);
 169         g_free(node);
 170     }
 171     bus->broadcast = false;
 172 }
 173
 174 int i2c_send_recv(I2CBus *bus, uint8_t *data, bool send)
 175 {
 176     I2CSlaveClass *sc;
 177     I2CSlave *s;
 178     I2CNode *node;
 179     int ret = 0;
 180
 181     if (send) {
 182         QLIST_FOREACH(node, &bus->current_devs, next) {
 183             s = node->elt;
 184             sc = I2C_SLAVE_GET_CLASS(s);
 185             if (sc->send) {
 186                 trace_i2c_send(s->address, *data);
 187                 ret = ret || sc->send(s, *data);
 188             } else {
 189                 ret = -1;
 190             }
 191         }
 192         return ret ? -1 : 0;
 193     } else {
 194         if ((QLIST_EMPTY(&bus->current_devs)) || (bus->broadcast)) {
 195             return -1;
 196         }
 197
 198         sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
 199         if (sc->recv) {
 200             s = QLIST_FIRST(&bus->current_devs)->elt;
 201             ret = sc->recv(s);
 202             trace_i2c_recv(s->address, ret);
 203             if (ret < 0) {
 204                 return ret;
 205             } else {
 206                 *data = ret;
 207                 return 0;
 208             }
 209         }
 210         return -1;
 211     }
 212 }
 213
 214 int i2c_send(I2CBus *bus, uint8_t data)
 215 {
 216     return i2c_send_recv(bus, &data, true);
 217 }
 218
 219 int i2c_recv(I2CBus *bus)
 220 {
 221     uint8_t data;
 222     int ret = i2c_send_recv(bus, &data, false);
 223
 224     return ret < 0 ? ret : data;
 225 }
 226
 227 void i2c_nack(I2CBus *bus)
 228 {
 229     I2CSlaveClass *sc;
 230     I2CNode *node;
 231
 232     if (QLIST_EMPTY(&bus->current_devs)) {
 233         return;
 234     }
 235
 236     QLIST_FOREACH(node, &bus->current_devs, next) {
 237         sc = I2C_SLAVE_GET_CLASS(node->elt);
 238         if (sc->event) {
 239             trace_i2c_event("nack", node->elt->address);
 240             sc->event(node->elt, I2C_NACK);
 241         }
 242     }
 243 }
 244
 245 static int i2c_slave_post_load(void *opaque, int version_id)
 246 {
 247     I2CSlave *dev = opaque;
 248     I2CBus *bus;
 249     I2CNode *node;
 250
 251     bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev)));
 252     if ((bus->saved_address == dev->address) ||
 253         (bus->saved_address == I2C_BROADCAST)) {
 254         node = g_malloc(sizeof(struct I2CNode));
 255         node->elt = dev;
 256         QLIST_INSERT_HEAD(&bus->current_devs, node, next);
 257     }
 258     return 0;
 259 }
 260
 261 const VMStateDescription vmstate_i2c_slave = {
 262     .name = "I2CSlave",
 263     .version_id = 1,
 264     .minimum_version_id = 1,
 265     .post_load = i2c_slave_post_load,
 266     .fields = (VMStateField[]) {
 267         VMSTATE_UINT8(address, I2CSlave),
 268         VMSTATE_END_OF_LIST()
 269     }
 270 };
 271
 272 DeviceState *i2c_create_slave(I2CBus *bus, const char *name, uint8_t addr)
 273 {
 274     DeviceState *dev;
 275
 276     dev = qdev_create(&bus->qbus, name);
 277     qdev_prop_set_uint8(dev, "address", addr);
 278     qdev_init_nofail(dev);
 279     return dev;
 280 }
 281
 282 static void i2c_slave_class_init(ObjectClass *klass, void *data)
 283 {
 284     DeviceClass *k = DEVICE_CLASS(klass);
 285     set_bit(DEVICE_CATEGORY_MISC, k->categories);
 286     k->bus_type = TYPE_I2C_BUS;
 287     k->props = i2c_props;
 288 }
 289
 290 static const TypeInfo i2c_slave_type_info = {
 291     .name = TYPE_I2C_SLAVE,
 292     .parent = TYPE_DEVICE,
 293     .instance_size = sizeof(I2CSlave),
 294     .abstract = true,
 295     .class_size = sizeof(I2CSlaveClass),
 296     .class_init = i2c_slave_class_init,
 297 };
 298
 299 static void i2c_slave_register_types(void)
 300 {
 301     type_register_static(&i2c_bus_info);
 302     type_register_static(&i2c_slave_type_info);
 303 }
 304
 305 type_init(i2c_slave_register_types)