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