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, -1, &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) |
303 | |