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