xref: /openbmc/qemu/hw/i2c/core.c (revision e09484ef) 
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 
13 typedef struct I2CNode I2CNode;
14 
15 struct I2CNode {
16     I2CSlave *elt;
17     QLIST_ENTRY(I2CNode) next;
18 };
19 
20 #define I2C_BROADCAST 0x00
21 
22 struct I2CBus
23 {
24     BusState qbus;
25     QLIST_HEAD(, I2CNode) current_devs;
26     uint8_t saved_address;
27     bool broadcast;
28 };
29 
30 static Property i2c_props[] = {
31     DEFINE_PROP_UINT8("address", struct I2CSlave, address, 0),
32     DEFINE_PROP_END_OF_LIST(),
33 };
34 
35 #define TYPE_I2C_BUS "i2c-bus"
36 #define I2C_BUS(obj) OBJECT_CHECK(I2CBus, (obj), TYPE_I2C_BUS)
37 
38 static const TypeInfo i2c_bus_info = {
39     .name = TYPE_I2C_BUS,
40     .parent = TYPE_BUS,
41     .instance_size = sizeof(I2CBus),
42 };
43 
44 static void i2c_bus_pre_save(void *opaque)
45 {
46     I2CBus *bus = opaque;
47 
48     bus->saved_address = -1;
49     if (!QLIST_EMPTY(&bus->current_devs)) {
50         if (!bus->broadcast) {
51             bus->saved_address = QLIST_FIRST(&bus->current_devs)->elt->address;
52         } else {
53             bus->saved_address = I2C_BROADCAST;
54         }
55     }
56 }
57 
58 static const VMStateDescription vmstate_i2c_bus = {
59     .name = "i2c_bus",
60     .version_id = 1,
61     .minimum_version_id = 1,
62     .pre_save = i2c_bus_pre_save,
63     .fields = (VMStateField[]) {
64         VMSTATE_UINT8(saved_address, I2CBus),
65         VMSTATE_END_OF_LIST()
66     }
67 };
68 
69 /* Create a new I2C bus.  */
70 I2CBus *i2c_init_bus(DeviceState *parent, const char *name)
71 {
72     I2CBus *bus;
73 
74     bus = I2C_BUS(qbus_create(TYPE_I2C_BUS, parent, name));
75     QLIST_INIT(&bus->current_devs);
76     vmstate_register(NULL, -1, &vmstate_i2c_bus, bus);
77     return bus;
78 }
79 
80 void i2c_set_slave_address(I2CSlave *dev, uint8_t address)
81 {
82     dev->address = address;
83 }
84 
85 /* Return nonzero if bus is busy.  */
86 int i2c_bus_busy(I2CBus *bus)
87 {
88     return !QLIST_EMPTY(&bus->current_devs);
89 }
90 
91 /* Returns non-zero if the address is not valid.  */
92 /* TODO: Make this handle multiple masters.  */
93 int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
94 {
95     BusChild *kid;
96     I2CSlaveClass *sc;
97     I2CNode *node;
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     QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
108         DeviceState *qdev = kid->child;
109         I2CSlave *candidate = I2C_SLAVE(qdev);
110         if ((candidate->address == address) || (bus->broadcast)) {
111             node = g_malloc(sizeof(struct I2CNode));
112             node->elt = candidate;
113             QLIST_INSERT_HEAD(&bus->current_devs, node, next);
114             if (!bus->broadcast) {
115                 break;
116             }
117         }
118     }
119 
120     if (QLIST_EMPTY(&bus->current_devs)) {
121         return 1;
122     }
123 
124     QLIST_FOREACH(node, &bus->current_devs, next) {
125         sc = I2C_SLAVE_GET_CLASS(node->elt);
126         /* If the bus is already busy, assume this is a repeated
127            start condition.  */
128         if (sc->event) {
129             sc->event(node->elt, recv ? I2C_START_RECV : I2C_START_SEND);
130         }
131     }
132     return 0;
133 }
134 
135 void i2c_end_transfer(I2CBus *bus)
136 {
137     I2CSlaveClass *sc;
138     I2CNode *node, *next;
139 
140     if (QLIST_EMPTY(&bus->current_devs)) {
141         return;
142     }
143 
144     QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) {
145         sc = I2C_SLAVE_GET_CLASS(node->elt);
146         if (sc->event) {
147             sc->event(node->elt, I2C_FINISH);
148         }
149         QLIST_REMOVE(node, next);
150         g_free(node);
151     }
152     bus->broadcast = false;
153 }
154 
155 int i2c_send_recv(I2CBus *bus, uint8_t *data, bool send)
156 {
157     I2CSlaveClass *sc;
158     I2CNode *node;
159     int ret = 0;
160 
161     if (send) {
162         QLIST_FOREACH(node, &bus->current_devs, next) {
163             sc = I2C_SLAVE_GET_CLASS(node->elt);
164             if (sc->send) {
165                 ret = ret || sc->send(node->elt, *data);
166             } else {
167                 ret = -1;
168             }
169         }
170         return ret ? -1 : 0;
171     } else {
172         if ((QLIST_EMPTY(&bus->current_devs)) || (bus->broadcast)) {
173             return -1;
174         }
175 
176         sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
177         if (sc->recv) {
178             ret = sc->recv(QLIST_FIRST(&bus->current_devs)->elt);
179             if (ret < 0) {
180                 return ret;
181             } else {
182                 *data = ret;
183                 return 0;
184             }
185         }
186         return -1;
187     }
188 }
189 
190 int i2c_send(I2CBus *bus, uint8_t data)
191 {
192     return i2c_send_recv(bus, &data, true);
193 }
194 
195 int i2c_recv(I2CBus *bus)
196 {
197     uint8_t data;
198     int ret = i2c_send_recv(bus, &data, false);
199 
200     return ret < 0 ? ret : data;
201 }
202 
203 void i2c_nack(I2CBus *bus)
204 {
205     I2CSlaveClass *sc;
206     I2CNode *node;
207 
208     if (QLIST_EMPTY(&bus->current_devs)) {
209         return;
210     }
211 
212     QLIST_FOREACH(node, &bus->current_devs, next) {
213         sc = I2C_SLAVE_GET_CLASS(node->elt);
214         if (sc->event) {
215             sc->event(node->elt, I2C_NACK);
216         }
217     }
218 }
219 
220 static int i2c_slave_post_load(void *opaque, int version_id)
221 {
222     I2CSlave *dev = opaque;
223     I2CBus *bus;
224     I2CNode *node;
225 
226     bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev)));
227     if ((bus->saved_address == dev->address) ||
228         (bus->saved_address == I2C_BROADCAST)) {
229         node = g_malloc(sizeof(struct I2CNode));
230         node->elt = dev;
231         QLIST_INSERT_HEAD(&bus->current_devs, node, next);
232     }
233     return 0;
234 }
235 
236 const VMStateDescription vmstate_i2c_slave = {
237     .name = "I2CSlave",
238     .version_id = 1,
239     .minimum_version_id = 1,
240     .post_load = i2c_slave_post_load,
241     .fields = (VMStateField[]) {
242         VMSTATE_UINT8(address, I2CSlave),
243         VMSTATE_END_OF_LIST()
244     }
245 };
246 
247 static int i2c_slave_qdev_init(DeviceState *dev)
248 {
249     I2CSlave *s = I2C_SLAVE(dev);
250     I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(s);
251 
252     return sc->init(s);
253 }
254 
255 DeviceState *i2c_create_slave(I2CBus *bus, const char *name, uint8_t addr)
256 {
257     DeviceState *dev;
258 
259     dev = qdev_create(&bus->qbus, name);
260     qdev_prop_set_uint8(dev, "address", addr);
261     qdev_init_nofail(dev);
262     return dev;
263 }
264 
265 static void i2c_slave_class_init(ObjectClass *klass, void *data)
266 {
267     DeviceClass *k = DEVICE_CLASS(klass);
268     k->init = i2c_slave_qdev_init;
269     set_bit(DEVICE_CATEGORY_MISC, k->categories);
270     k->bus_type = TYPE_I2C_BUS;
271     k->props = i2c_props;
272 }
273 
274 static const TypeInfo i2c_slave_type_info = {
275     .name = TYPE_I2C_SLAVE,
276     .parent = TYPE_DEVICE,
277     .instance_size = sizeof(I2CSlave),
278     .abstract = true,
279     .class_size = sizeof(I2CSlaveClass),
280     .class_init = i2c_slave_class_init,
281 };
282 
283 static void i2c_slave_register_types(void)
284 {
285     type_register_static(&i2c_bus_info);
286     type_register_static(&i2c_slave_type_info);
287 }
288 
289 type_init(i2c_slave_register_types)
290