2 * QEMU I2C bus interface.
4 * Copyright (c) 2007 CodeSourcery.
5 * Written by Paul Brook
7 * This code is licensed under the LGPL.
10 #include "qemu/osdep.h"
11 #include "hw/i2c/i2c.h"
13 #define I2C_BROADCAST 0x00
15 static Property i2c_props
[] = {
16 DEFINE_PROP_UINT8("address", struct I2CSlave
, address
, 0),
17 DEFINE_PROP_END_OF_LIST(),
20 static const TypeInfo i2c_bus_info
= {
23 .instance_size
= sizeof(I2CBus
),
26 static int i2c_bus_pre_save(void *opaque
)
30 bus
->saved_address
= -1;
31 if (!QLIST_EMPTY(&bus
->current_devs
)) {
32 if (!bus
->broadcast
) {
33 bus
->saved_address
= QLIST_FIRST(&bus
->current_devs
)->elt
->address
;
35 bus
->saved_address
= I2C_BROADCAST
;
42 static const VMStateDescription vmstate_i2c_bus
= {
45 .minimum_version_id
= 1,
46 .pre_save
= i2c_bus_pre_save
,
47 .fields
= (VMStateField
[]) {
48 VMSTATE_UINT8(saved_address
, I2CBus
),
53 /* Create a new I2C bus. */
54 I2CBus
*i2c_init_bus(DeviceState
*parent
, const char *name
)
58 bus
= I2C_BUS(qbus_create(TYPE_I2C_BUS
, parent
, name
));
59 QLIST_INIT(&bus
->current_devs
);
60 vmstate_register(NULL
, -1, &vmstate_i2c_bus
, bus
);
64 void i2c_set_slave_address(I2CSlave
*dev
, uint8_t address
)
66 dev
->address
= address
;
69 /* Return nonzero if bus is busy. */
70 int i2c_bus_busy(I2CBus
*bus
)
72 return !QLIST_EMPTY(&bus
->current_devs
);
75 /* TODO: Make this handle multiple masters. */
77 * Start or continue an i2c transaction. When this is called for the
78 * first time or after an i2c_end_transfer(), if it returns an error
79 * the bus transaction is terminated (or really never started). If
80 * this is called after another i2c_start_transfer() without an
81 * intervening i2c_end_transfer(), and it returns an error, the
82 * transaction will not be terminated. The caller must do it.
84 * This corresponds with the way real hardware works. The SMBus
85 * protocol uses a start transfer to switch from write to read mode
86 * without releasing the bus. If that fails, the bus is still
89 int i2c_start_transfer(I2CBus
*bus
, uint8_t address
, int recv
)
94 bool bus_scanned
= false;
96 if (address
== I2C_BROADCAST
) {
98 * This is a broadcast, the current_devs will be all the devices of the
101 bus
->broadcast
= true;
105 * If there are already devices in the list, that means we are in
106 * the middle of a transaction and we shouldn't rescan the bus.
108 * This happens with any SMBus transaction, even on a pure I2C
109 * device. The interface does a transaction start without
110 * terminating the previous transaction.
112 if (QLIST_EMPTY(&bus
->current_devs
)) {
113 QTAILQ_FOREACH(kid
, &bus
->qbus
.children
, sibling
) {
114 DeviceState
*qdev
= kid
->child
;
115 I2CSlave
*candidate
= I2C_SLAVE(qdev
);
116 if ((candidate
->address
== address
) || (bus
->broadcast
)) {
117 node
= g_malloc(sizeof(struct I2CNode
));
118 node
->elt
= candidate
;
119 QLIST_INSERT_HEAD(&bus
->current_devs
, node
, next
);
120 if (!bus
->broadcast
) {
128 if (QLIST_EMPTY(&bus
->current_devs
)) {
132 QLIST_FOREACH(node
, &bus
->current_devs
, next
) {
135 sc
= I2C_SLAVE_GET_CLASS(node
->elt
);
136 /* If the bus is already busy, assume this is a repeated
140 rv
= sc
->event(node
->elt
, recv
? I2C_START_RECV
: I2C_START_SEND
);
141 if (rv
&& !bus
->broadcast
) {
143 /* First call, terminate the transfer. */
144 i2c_end_transfer(bus
);
153 void i2c_end_transfer(I2CBus
*bus
)
156 I2CNode
*node
, *next
;
158 QLIST_FOREACH_SAFE(node
, &bus
->current_devs
, next
, next
) {
159 sc
= I2C_SLAVE_GET_CLASS(node
->elt
);
161 sc
->event(node
->elt
, I2C_FINISH
);
163 QLIST_REMOVE(node
, next
);
166 bus
->broadcast
= false;
169 int i2c_send_recv(I2CBus
*bus
, uint8_t *data
, bool send
)
176 QLIST_FOREACH(node
, &bus
->current_devs
, next
) {
177 sc
= I2C_SLAVE_GET_CLASS(node
->elt
);
179 ret
= ret
|| sc
->send(node
->elt
, *data
);
186 if ((QLIST_EMPTY(&bus
->current_devs
)) || (bus
->broadcast
)) {
190 sc
= I2C_SLAVE_GET_CLASS(QLIST_FIRST(&bus
->current_devs
)->elt
);
192 ret
= sc
->recv(QLIST_FIRST(&bus
->current_devs
)->elt
);
204 int i2c_send(I2CBus
*bus
, uint8_t data
)
206 return i2c_send_recv(bus
, &data
, true);
209 int i2c_recv(I2CBus
*bus
)
212 int ret
= i2c_send_recv(bus
, &data
, false);
214 return ret
< 0 ? ret
: data
;
217 void i2c_nack(I2CBus
*bus
)
222 if (QLIST_EMPTY(&bus
->current_devs
)) {
226 QLIST_FOREACH(node
, &bus
->current_devs
, next
) {
227 sc
= I2C_SLAVE_GET_CLASS(node
->elt
);
229 sc
->event(node
->elt
, I2C_NACK
);
234 static int i2c_slave_post_load(void *opaque
, int version_id
)
236 I2CSlave
*dev
= opaque
;
240 bus
= I2C_BUS(qdev_get_parent_bus(DEVICE(dev
)));
241 if ((bus
->saved_address
== dev
->address
) ||
242 (bus
->saved_address
== I2C_BROADCAST
)) {
243 node
= g_malloc(sizeof(struct I2CNode
));
245 QLIST_INSERT_HEAD(&bus
->current_devs
, node
, next
);
250 const VMStateDescription vmstate_i2c_slave
= {
253 .minimum_version_id
= 1,
254 .post_load
= i2c_slave_post_load
,
255 .fields
= (VMStateField
[]) {
256 VMSTATE_UINT8(address
, I2CSlave
),
257 VMSTATE_END_OF_LIST()
261 DeviceState
*i2c_create_slave(I2CBus
*bus
, const char *name
, uint8_t addr
)
265 dev
= qdev_create(&bus
->qbus
, name
);
266 qdev_prop_set_uint8(dev
, "address", addr
);
267 qdev_init_nofail(dev
);
271 static void i2c_slave_class_init(ObjectClass
*klass
, void *data
)
273 DeviceClass
*k
= DEVICE_CLASS(klass
);
274 set_bit(DEVICE_CATEGORY_MISC
, k
->categories
);
275 k
->bus_type
= TYPE_I2C_BUS
;
276 k
->props
= i2c_props
;
279 static const TypeInfo i2c_slave_type_info
= {
280 .name
= TYPE_I2C_SLAVE
,
281 .parent
= TYPE_DEVICE
,
282 .instance_size
= sizeof(I2CSlave
),
284 .class_size
= sizeof(I2CSlaveClass
),
285 .class_init
= i2c_slave_class_init
,
288 static void i2c_slave_register_types(void)
290 type_register_static(&i2c_bus_info
);
291 type_register_static(&i2c_slave_type_info
);
294 type_init(i2c_slave_register_types
)