xref: /openbmc/qemu/hw/i2c/core.c (revision 35658f6e) 
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 struct I2CBus
21 {
22     BusState qbus;
23     QLIST_HEAD(, I2CNode) current_devs;
24     uint8_t saved_address;
25     bool broadcast;
26 };
27 
28 static Property i2c_props[] = {
29     DEFINE_PROP_UINT8("address", struct I2CSlave, address, 0),
30     DEFINE_PROP_END_OF_LIST(),
31 };
32 
33 #define TYPE_I2C_BUS "i2c-bus"
34 #define I2C_BUS(obj) OBJECT_CHECK(I2CBus, (obj), TYPE_I2C_BUS)
35 
36 static const TypeInfo i2c_bus_info = {
37     .name = TYPE_I2C_BUS,
38     .parent = TYPE_BUS,
39     .instance_size = sizeof(I2CBus),
40 };
41 
42 static void i2c_bus_pre_save(void *opaque)
43 {
44     I2CBus *bus = opaque;
45 
46     bus->saved_address = -1;
47     if (!QLIST_EMPTY(&bus->current_devs)) {
48         if (!bus->broadcast) {
49             bus->saved_address = QLIST_FIRST(&bus->current_devs)->elt->address;
50         }
51     }
52 }
53 
54 static const VMStateDescription vmstate_i2c_bus = {
55     .name = "i2c_bus",
56     .version_id = 1,
57     .minimum_version_id = 1,
58     .pre_save = i2c_bus_pre_save,
59     .fields = (VMStateField[]) {
60         VMSTATE_UINT8(saved_address, I2CBus),
61         VMSTATE_BOOL(broadcast, I2CBus),
62         VMSTATE_END_OF_LIST()
63     }
64 };
65 
66 /* Create a new I2C bus.  */
67 I2CBus *i2c_init_bus(DeviceState *parent, const char *name)
68 {
69     I2CBus *bus;
70 
71     bus = I2C_BUS(qbus_create(TYPE_I2C_BUS, parent, name));
72     QLIST_INIT(&bus->current_devs);
73     vmstate_register(NULL, -1, &vmstate_i2c_bus, bus);
74     return bus;
75 }
76 
77 void i2c_set_slave_address(I2CSlave *dev, uint8_t address)
78 {
79     dev->address = address;
80 }
81 
82 /* Return nonzero if bus is busy.  */
83 int i2c_bus_busy(I2CBus *bus)
84 {
85     return !QLIST_EMPTY(&bus->current_devs);
86 }
87 
88 /* Returns non-zero if the address is not valid.  */
89 /* TODO: Make this handle multiple masters.  */
90 int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
91 {
92     BusChild *kid;
93     I2CSlaveClass *sc;
94     I2CNode *node;
95 
96     if (address == 0x00) {
97         /*
98          * This is a broadcast, the current_devs will be all the devices of the
99          * bus.
100          */
101         bus->broadcast = true;
102     }
103 
104     QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
105         DeviceState *qdev = kid->child;
106         I2CSlave *candidate = I2C_SLAVE(qdev);
107         if ((candidate->address == address) || (bus->broadcast)) {
108             node = g_malloc(sizeof(struct I2CNode));
109             node->elt = candidate;
110             QLIST_INSERT_HEAD(&bus->current_devs, node, next);
111             if (!bus->broadcast) {
112                 break;
113             }
114         }
115     }
116 
117     if (QLIST_EMPTY(&bus->current_devs)) {
118         return 1;
119     }
120 
121     QLIST_FOREACH(node, &bus->current_devs, next) {
122         sc = I2C_SLAVE_GET_CLASS(node->elt);
123         /* If the bus is already busy, assume this is a repeated
124            start condition.  */
125         if (sc->event) {
126             sc->event(node->elt, recv ? I2C_START_RECV : I2C_START_SEND);
127         }
128     }
129     return 0;
130 }
131 
132 void i2c_end_transfer(I2CBus *bus)
133 {
134     I2CSlaveClass *sc;
135     I2CNode *node, *next;
136 
137     if (QLIST_EMPTY(&bus->current_devs)) {
138         return;
139     }
140 
141     QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) {
142         sc = I2C_SLAVE_GET_CLASS(node->elt);
143         if (sc->event) {
144             sc->event(node->elt, I2C_FINISH);
145         }
146         QLIST_REMOVE(node, next);
147         g_free(node);
148     }
149     bus->broadcast = false;
150 }
151 
152 int i2c_send_recv(I2CBus *bus, uint8_t *data, bool send)
153 {
154     I2CSlaveClass *sc;
155     I2CNode *node;
156     int ret = 0;
157 
158     if (send) {
159         QLIST_FOREACH(node, &bus->current_devs, next) {
160             sc = I2C_SLAVE_GET_CLASS(node->elt);
161             if (sc->send) {
162                 ret = ret || sc->send(node->elt, *data);
163             } else {
164                 ret = -1;
165             }
166         }
167         return ret ? -1 : 0;
168     } else {
169         if ((QLIST_EMPTY(&bus->current_devs)) || (bus->broadcast)) {
170             return -1;
171         }
172 
173         sc = I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus->current_devs)->elt);
174         if (sc->recv) {
175             ret = sc->recv(QLIST_FIRST(&bus->current_devs)->elt);
176             if (ret < 0) {
177                 return ret;
178             } else {
179                 *data = ret;
180                 return 0;
181             }
182         }
183         return -1;
184     }
185 }
186 
187 int i2c_send(I2CBus *bus, uint8_t data)
188 {
189     return i2c_send_recv(bus, &data, true);
190 }
191 
192 int i2c_recv(I2CBus *bus)
193 {
194     uint8_t data;
195     int ret = i2c_send_recv(bus, &data, false);
196 
197     return ret < 0 ? ret : data;
198 }
199 
200 void i2c_nack(I2CBus *bus)
201 {
202     I2CSlaveClass *sc;
203     I2CNode *node;
204 
205     if (QLIST_EMPTY(&bus->current_devs)) {
206         return;
207     }
208 
209     QLIST_FOREACH(node, &bus->current_devs, next) {
210         sc = I2C_SLAVE_GET_CLASS(node->elt);
211         if (sc->event) {
212             sc->event(node->elt, I2C_NACK);
213         }
214     }
215 }
216 
217 static int i2c_slave_post_load(void *opaque, int version_id)
218 {
219     I2CSlave *dev = opaque;
220     I2CBus *bus;
221     I2CNode *node;
222 
223     bus = I2C_BUS(qdev_get_parent_bus(DEVICE(dev)));
224     if ((bus->saved_address == dev->address) || (bus->broadcast)) {
225         node = g_malloc(sizeof(struct I2CNode));
226         node->elt = dev;
227         QLIST_INSERT_HEAD(&bus->current_devs, node, next);
228     }
229     return 0;
230 }
231 
232 const VMStateDescription vmstate_i2c_slave = {
233     .name = "I2CSlave",
234     .version_id = 1,
235     .minimum_version_id = 1,
236     .post_load = i2c_slave_post_load,
237     .fields = (VMStateField[]) {
238         VMSTATE_UINT8(address, I2CSlave),
239         VMSTATE_END_OF_LIST()
240     }
241 };
242 
243 static int i2c_slave_qdev_init(DeviceState *dev)
244 {
245     I2CSlave *s = I2C_SLAVE(dev);
246     I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(s);
247 
248     return sc->init(s);
249 }
250 
251 DeviceState *i2c_create_slave(I2CBus *bus, const char *name, uint8_t addr)
252 {
253     DeviceState *dev;
254 
255     dev = qdev_create(&bus->qbus, name);
256     qdev_prop_set_uint8(dev, "address", addr);
257     qdev_init_nofail(dev);
258     return dev;
259 }
260 
261 static void i2c_slave_class_init(ObjectClass *klass, void *data)
262 {
263     DeviceClass *k = DEVICE_CLASS(klass);
264     k->init = i2c_slave_qdev_init;
265     set_bit(DEVICE_CATEGORY_MISC, k->categories);
266     k->bus_type = TYPE_I2C_BUS;
267     k->props = i2c_props;
268 }
269 
270 static const TypeInfo i2c_slave_type_info = {
271     .name = TYPE_I2C_SLAVE,
272     .parent = TYPE_DEVICE,
273     .instance_size = sizeof(I2CSlave),
274     .abstract = true,
275     .class_size = sizeof(I2CSlaveClass),
276     .class_init = i2c_slave_class_init,
277 };
278 
279 static void i2c_slave_register_types(void)
280 {
281     type_register_static(&i2c_bus_info);
282     type_register_static(&i2c_slave_type_info);
283 }
284 
285 type_init(i2c_slave_register_types)
286