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_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
i2c_set_slave_address(I2CSlave * dev,uint8_t address)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. */
i2c_bus_busy(I2CBus * bus)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 */
i2c_start_transfer(I2CBus * bus,uint8_t address,int recv)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
i2c_end_transfer(I2CBus * bus)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
i2c_send_recv(I2CBus * bus,uint8_t * data,bool send)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
i2c_send(I2CBus * bus,uint8_t data)212 int i2c_send(I2CBus *bus, uint8_t data)
213 {
214 return i2c_send_recv(bus, &data, true);
215 }
216
i2c_recv(I2CBus * bus)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
i2c_nack(I2CBus * bus)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
i2c_slave_post_load(void * opaque,int version_id)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
i2c_slave_new(const char * name,uint8_t addr)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
i2c_slave_realize_and_unref(I2CSlave * dev,I2CBus * bus,Error ** errp)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
i2c_slave_create_simple(I2CBus * bus,const char * name,uint8_t addr)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
i2c_slave_class_init(ObjectClass * klass,void * data)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
i2c_slave_register_types(void)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)
317