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 /* TODO: Make this handle multiple masters.  */
  81 /*
  82  * Start or continue an i2c transaction.  When this is called for the
  83  * first time or after an i2c_end_transfer(), if it returns an error
  84  * the bus transaction is terminated (or really never started).  If
  85  * this is called after another i2c_start_transfer() without an
  86  * intervening i2c_end_transfer(), and it returns an error, the
  87  * transaction will not be terminated.  The caller must do it.
  88  *
  89  * This corresponds with the way real hardware works.  The SMBus
  90  * protocol uses a start transfer to switch from write to read mode
  91  * without releasing the bus.  If that fails, the bus is still
  92  * in a transaction.
  93  */
  94 int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
  95 {
  96     BusChild *kid;
  97     I2CSlaveClass *sc;
  98     I2CNode *node;
  99     bool bus_scanned = false;
 100
 101     if (address == I2C_BROADCAST) {
 102         /*
 103          * This is a broadcast, the current_devs will be all the devices of the
 104          * bus.
 105          */
 106         bus->broadcast = true;
 107     }
 108
 109     /*
 110      * If there are already devices in the list, that means we are in
 111      * the middle of a transaction and we shouldn't rescan the bus.
 112      *
 113      * This happens with any SMBus transaction, even on a pure I2C
 114      * device.  The interface does a transaction start without
 115      * terminating the previous transaction.
 116      */
 117     if (QLIST_EMPTY(&bus->current_devs)) {
 118         QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
 119             DeviceState *qdev = kid->child;
 120             I2CSlave *candidate = I2C_SLAVE(qdev);
 121             if ((candidate->address == address) || (bus->broadcast)) {
 122                 node = g_malloc(sizeof(struct I2CNode));
 123                 node->elt = candidate;
 124                 QLIST_INSERT_HEAD(&bus->current_devs, node, next);
 125                 if (!bus->broadcast) {
 126                     break;
 127                 }
 128             }
 129         }
 130         bus_scanned = true;
 131     }
 132
 133     if (QLIST_EMPTY(&bus->current_devs)) {
 134         return 1;
 135     }
 136
 137     QLIST_FOREACH(node, &bus->current_devs, next) {
 138         I2CSlave *s = node->elt;
 139         int rv;
 140
 141         sc = I2C_SLAVE_GET_CLASS(s);
 142         /* If the bus is already busy, assume this is a repeated
 143            start condition.  */
 144
 145         if (sc->event) {
 146             trace_i2c_event("start", s->address);
 147             rv = sc->event(s, recv ? I2C_START_RECV : I2C_START_SEND);
 148             if (rv && !bus->broadcast) {
 149                 if (bus_scanned) {
 150                     /* First call, terminate the transfer. */
 151                     i2c_end_transfer(bus);
 152                 }
 153                 return rv;
 154             }
 155         }
 156     }
 157     return 0;
 158 }
 159
 160 void i2c_end_transfer(I2CBus *bus)
 161 {
 162     I2CSlaveClass *sc;
 163     I2CNode *node, *next;
 164
 165     QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) {
 166         I2CSlave *s = node->elt;
 167         sc = I2C_SLAVE_GET_CLASS(s);
 168         if (sc->event) {
 169             trace_i2c_event("finish", s->address);
 170             sc->event(s, I2C_FINISH);
 171         }
 172         QLIST_REMOVE(node, next);
 173         g_free(node);
 174     }
 175     bus->broadcast = false;
 176 }
 177
 178 int i2c_send_recv(I2CBus *bus, uint8_t *data, bool send)
 179 {
 180     I2CSlaveClass *sc;
 181     I2CSlave *s;
 182     I2CNode *node;
 183     int ret = 0;
 184
 185     if (send) {
 186         QLIST_FOREACH(node, &bus->current_devs, next) {
 187             s = node->elt;
 188             sc = I2C_SLAVE_GET_CLASS(s);
 189             if (sc->send) {
 190                 trace_i2c_send(s->address, *data);
 191                 ret = ret || sc->send(s, *data);
 192             } else {
 193                 ret = -1;
 194             }
 195         }
 196         return ret ? -1 : 0;
 197     } else {
 198         ret = 0xff;
 199         if (!QLIST_EMPTY(&bus->current_devs) && !bus->broadcast) {
 200             sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
 201             if (sc->recv) {
 202                 s = QLIST_FIRST(&bus->current_devs)->elt;
 203                 ret = sc->recv(s);
 204                 trace_i2c_recv(s->address, ret);
 205             }
 206         }
 207         *data = ret;
 208         return 0;
 209     }
 210 }
 211
 212 int i2c_send(I2CBus *bus, uint8_t data)
 213 {
 214     return i2c_send_recv(bus, &data, true);
 215 }
 216
 217 uint8_t i2c_recv(I2CBus *bus)
 218 {
 219     uint8_t data = 0xff;
 220
 221     i2c_send_recv(bus, &data, false);
 222     return data;
 223 }
 224
 225 void i2c_nack(I2CBus *bus)
 226 {
 227     I2CSlaveClass *sc;
 228     I2CNode *node;
 229
 230     if (QLIST_EMPTY(&bus->current_devs)) {
 231         return;
 232     }
 233
 234     QLIST_FOREACH(node, &bus->current_devs, next) {
 235         sc = I2C_SLAVE_GET_CLASS(node->elt);
 236         if (sc->event) {
 237             trace_i2c_event("nack", node->elt->address);
 238             sc->event(node->elt, I2C_NACK);
 239         }
 240     }
 241 }
 242
 243 static int i2c_slave_post_load(void *opaque, int version_id)
 244 {
 245     I2CSlave *dev = opaque;
 246     I2CBus *bus;
 247     I2CNode *node;
 248
 249     bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev)));
 250     if ((bus->saved_address == dev->address) ||
 251         (bus->saved_address == I2C_BROADCAST)) {
 252         node = g_malloc(sizeof(struct I2CNode));
 253         node->elt = dev;
 254         QLIST_INSERT_HEAD(&bus->current_devs, node, next);
 255     }
 256     return 0;
 257 }
 258
 259 const VMStateDescription vmstate_i2c_slave = {
 260     .name = "I2CSlave",
 261     .version_id = 1,
 262     .minimum_version_id = 1,
 263     .post_load = i2c_slave_post_load,
 264     .fields = (VMStateField[]) {
 265         VMSTATE_UINT8(address, I2CSlave),
 266         VMSTATE_END_OF_LIST()
 267     }
 268 };
 269
 270 I2CSlave *i2c_slave_new(const char *name, uint8_t addr)
 271 {
 272     DeviceState *dev;
 273
 274     dev = qdev_new(name);
 275     qdev_prop_set_uint8(dev, "address", addr);
 276     return I2C_SLAVE(dev);
 277 }
 278
 279 bool i2c_slave_realize_and_unref(I2CSlave *dev, I2CBus *bus, Error **errp)
 280 {
 281     return qdev_realize_and_unref(&dev->qdev, &bus->qbus, errp);
 282 }
 283
 284 I2CSlave *i2c_slave_create_simple(I2CBus *bus, const char *name, uint8_t addr)
 285 {
 286     I2CSlave *dev = i2c_slave_new(name, addr);
 287
 288     i2c_slave_realize_and_unref(dev, bus, &error_abort);
 289
 290     return dev;
 291 }
 292
 293 static void i2c_slave_class_init(ObjectClass *klass, void *data)
 294 {
 295     DeviceClass *k = DEVICE_CLASS(klass);
 296     set_bit(DEVICE_CATEGORY_MISC, k->categories);
 297     k->bus_type = TYPE_I2C_BUS;
 298     device_class_set_props(k, i2c_props);
 299 }
 300
 301 static const TypeInfo i2c_slave_type_info = {
 302     .name = TYPE_I2C_SLAVE,
 303     .parent = TYPE_DEVICE,
 304     .instance_size = sizeof(I2CSlave),
 305     .abstract = true,
 306     .class_size = sizeof(I2CSlaveClass),
 307     .class_init = i2c_slave_class_init,
 308 };
 309
 310 static void i2c_slave_register_types(void)
 311 {
 312     type_register_static(&i2c_bus_info);
 313     type_register_static(&i2c_slave_type_info);
 314 }
 315
 316 type_init(i2c_slave_register_types)