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