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
i2c_bus_pre_save(void * opaque)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. */
i2c_init_bus(DeviceState * parent,const char * name)59 I2CBus *i2c_init_bus(DeviceState *parent, const char *name)
60 {
61 I2CBus *bus;
62
63 bus = I2C_BUS(qbus_new(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
i2c_slave_set_address(I2CSlave * dev,uint8_t address)69 void i2c_slave_set_address(I2CSlave *dev, uint8_t address)
70 {
71 dev->address = address;
72 }
73
74 /* Return nonzero if bus is busy. */
i2c_bus_busy(I2CBus * bus)75 int i2c_bus_busy(I2CBus *bus)
76 {
77 return !QLIST_EMPTY(&bus->current_devs);
78 }
79
i2c_scan_bus(I2CBus * bus,uint8_t address,bool broadcast,I2CNodeList * current_devs)80 bool i2c_scan_bus(I2CBus *bus, uint8_t address, bool broadcast,
81 I2CNodeList *current_devs)
82 {
83 BusChild *kid;
84
85 QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
86 DeviceState *qdev = kid->child;
87 I2CSlave *candidate = I2C_SLAVE(qdev);
88 I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(candidate);
89
90 if (sc->match_and_add(candidate, address, broadcast, current_devs)) {
91 if (!broadcast) {
92 return true;
93 }
94 }
95 }
96
97 /*
98 * If broadcast was true, and the list was full or empty, return true. If
99 * broadcast was false, return false.
100 */
101 return broadcast;
102 }
103
104 /* TODO: Make this handle multiple masters. */
105 /*
106 * Start or continue an i2c transaction. When this is called for the
107 * first time or after an i2c_end_transfer(), if it returns an error
108 * the bus transaction is terminated (or really never started). If
109 * this is called after another i2c_start_transfer() without an
110 * intervening i2c_end_transfer(), and it returns an error, the
111 * transaction will not be terminated. The caller must do it.
112 *
113 * This corresponds with the way real hardware works. The SMBus
114 * protocol uses a start transfer to switch from write to read mode
115 * without releasing the bus. If that fails, the bus is still
116 * in a transaction.
117 *
118 * @event must be I2C_START_RECV or I2C_START_SEND.
119 */
i2c_do_start_transfer(I2CBus * bus,uint8_t address,enum i2c_event event)120 static int i2c_do_start_transfer(I2CBus *bus, uint8_t address,
121 enum i2c_event event)
122 {
123 I2CSlaveClass *sc;
124 I2CNode *node;
125 bool bus_scanned = false;
126
127 if (address == I2C_BROADCAST) {
128 /*
129 * This is a broadcast, the current_devs will be all the devices of the
130 * bus.
131 */
132 bus->broadcast = true;
133 }
134
135 /*
136 * If there are already devices in the list, that means we are in
137 * the middle of a transaction and we shouldn't rescan the bus.
138 *
139 * This happens with any SMBus transaction, even on a pure I2C
140 * device. The interface does a transaction start without
141 * terminating the previous transaction.
142 */
143 if (QLIST_EMPTY(&bus->current_devs)) {
144 /* Disregard whether devices were found. */
145 (void)i2c_scan_bus(bus, address, bus->broadcast, &bus->current_devs);
146 bus_scanned = true;
147 }
148
149 if (QLIST_EMPTY(&bus->current_devs)) {
150 return 1;
151 }
152
153 QLIST_FOREACH(node, &bus->current_devs, next) {
154 I2CSlave *s = node->elt;
155 int rv;
156
157 sc = I2C_SLAVE_GET_CLASS(s);
158 /* If the bus is already busy, assume this is a repeated
159 start condition. */
160
161 if (sc->event) {
162 trace_i2c_event("start", s->address);
163 rv = sc->event(s, event);
164 if (rv && !bus->broadcast) {
165 if (bus_scanned) {
166 /* First call, terminate the transfer. */
167 i2c_end_transfer(bus);
168 }
169 return rv;
170 }
171 }
172 }
173 return 0;
174 }
175
i2c_start_transfer(I2CBus * bus,uint8_t address,bool is_recv)176 int i2c_start_transfer(I2CBus *bus, uint8_t address, bool is_recv)
177 {
178 return i2c_do_start_transfer(bus, address, is_recv
179 ? I2C_START_RECV
180 : I2C_START_SEND);
181 }
182
i2c_start_recv(I2CBus * bus,uint8_t address)183 int i2c_start_recv(I2CBus *bus, uint8_t address)
184 {
185 return i2c_do_start_transfer(bus, address, I2C_START_RECV);
186 }
187
i2c_start_send(I2CBus * bus,uint8_t address)188 int i2c_start_send(I2CBus *bus, uint8_t address)
189 {
190 return i2c_do_start_transfer(bus, address, I2C_START_SEND);
191 }
192
i2c_end_transfer(I2CBus * bus)193 void i2c_end_transfer(I2CBus *bus)
194 {
195 I2CSlaveClass *sc;
196 I2CNode *node, *next;
197
198 QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) {
199 I2CSlave *s = node->elt;
200 sc = I2C_SLAVE_GET_CLASS(s);
201 if (sc->event) {
202 trace_i2c_event("finish", s->address);
203 sc->event(s, I2C_FINISH);
204 }
205 QLIST_REMOVE(node, next);
206 g_free(node);
207 }
208 bus->broadcast = false;
209 }
210
i2c_send(I2CBus * bus,uint8_t data)211 int i2c_send(I2CBus *bus, uint8_t data)
212 {
213 I2CSlaveClass *sc;
214 I2CSlave *s;
215 I2CNode *node;
216 int ret = 0;
217
218 QLIST_FOREACH(node, &bus->current_devs, next) {
219 s = node->elt;
220 sc = I2C_SLAVE_GET_CLASS(s);
221 if (sc->send) {
222 trace_i2c_send(s->address, data);
223 ret = ret || sc->send(s, data);
224 } else {
225 ret = -1;
226 }
227 }
228
229 return ret ? -1 : 0;
230 }
231
i2c_recv(I2CBus * bus)232 uint8_t i2c_recv(I2CBus *bus)
233 {
234 uint8_t data = 0xff;
235 I2CSlaveClass *sc;
236 I2CSlave *s;
237
238 if (!QLIST_EMPTY(&bus->current_devs) && !bus->broadcast) {
239 sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
240 if (sc->recv) {
241 s = QLIST_FIRST(&bus->current_devs)->elt;
242 data = sc->recv(s);
243 trace_i2c_recv(s->address, data);
244 }
245 }
246
247 return data;
248 }
249
i2c_nack(I2CBus * bus)250 void i2c_nack(I2CBus *bus)
251 {
252 I2CSlaveClass *sc;
253 I2CNode *node;
254
255 if (QLIST_EMPTY(&bus->current_devs)) {
256 return;
257 }
258
259 QLIST_FOREACH(node, &bus->current_devs, next) {
260 sc = I2C_SLAVE_GET_CLASS(node->elt);
261 if (sc->event) {
262 trace_i2c_event("nack", node->elt->address);
263 sc->event(node->elt, I2C_NACK);
264 }
265 }
266 }
267
i2c_slave_post_load(void * opaque,int version_id)268 static int i2c_slave_post_load(void *opaque, int version_id)
269 {
270 I2CSlave *dev = opaque;
271 I2CBus *bus;
272 I2CNode *node;
273
274 bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev)));
275 if ((bus->saved_address == dev->address) ||
276 (bus->saved_address == I2C_BROADCAST)) {
277 node = g_malloc(sizeof(struct I2CNode));
278 node->elt = dev;
279 QLIST_INSERT_HEAD(&bus->current_devs, node, next);
280 }
281 return 0;
282 }
283
284 const VMStateDescription vmstate_i2c_slave = {
285 .name = "I2CSlave",
286 .version_id = 1,
287 .minimum_version_id = 1,
288 .post_load = i2c_slave_post_load,
289 .fields = (VMStateField[]) {
290 VMSTATE_UINT8(address, I2CSlave),
291 VMSTATE_END_OF_LIST()
292 }
293 };
294
i2c_slave_new(const char * name,uint8_t addr)295 I2CSlave *i2c_slave_new(const char *name, uint8_t addr)
296 {
297 DeviceState *dev;
298
299 dev = qdev_new(name);
300 qdev_prop_set_uint8(dev, "address", addr);
301 return I2C_SLAVE(dev);
302 }
303
i2c_slave_realize_and_unref(I2CSlave * dev,I2CBus * bus,Error ** errp)304 bool i2c_slave_realize_and_unref(I2CSlave *dev, I2CBus *bus, Error **errp)
305 {
306 return qdev_realize_and_unref(&dev->qdev, &bus->qbus, errp);
307 }
308
i2c_slave_create_simple(I2CBus * bus,const char * name,uint8_t addr)309 I2CSlave *i2c_slave_create_simple(I2CBus *bus, const char *name, uint8_t addr)
310 {
311 I2CSlave *dev = i2c_slave_new(name, addr);
312
313 i2c_slave_realize_and_unref(dev, bus, &error_abort);
314
315 return dev;
316 }
317
i2c_slave_match(I2CSlave * candidate,uint8_t address,bool broadcast,I2CNodeList * current_devs)318 static bool i2c_slave_match(I2CSlave *candidate, uint8_t address,
319 bool broadcast, I2CNodeList *current_devs)
320 {
321 if ((candidate->address == address) || (broadcast)) {
322 I2CNode *node = g_malloc(sizeof(struct I2CNode));
323 node->elt = candidate;
324 QLIST_INSERT_HEAD(current_devs, node, next);
325 return true;
326 }
327
328 /* Not found and not broadcast. */
329 return false;
330 }
331
i2c_slave_class_init(ObjectClass * klass,void * data)332 static void i2c_slave_class_init(ObjectClass *klass, void *data)
333 {
334 DeviceClass *k = DEVICE_CLASS(klass);
335 I2CSlaveClass *sc = I2C_SLAVE_CLASS(klass);
336 set_bit(DEVICE_CATEGORY_MISC, k->categories);
337 k->bus_type = TYPE_I2C_BUS;
338 device_class_set_props(k, i2c_props);
339 sc->match_and_add = i2c_slave_match;
340 }
341
342 static const TypeInfo i2c_slave_type_info = {
343 .name = TYPE_I2C_SLAVE,
344 .parent = TYPE_DEVICE,
345 .instance_size = sizeof(I2CSlave),
346 .abstract = true,
347 .class_size = sizeof(I2CSlaveClass),
348 .class_init = i2c_slave_class_init,
349 };
350
i2c_slave_register_types(void)351 static void i2c_slave_register_types(void)
352 {
353 type_register_static(&i2c_bus_info);
354 type_register_static(&i2c_slave_type_info);
355 }
356
357 type_init(i2c_slave_register_types)
358