xref: /illumos-kvm-cmd/hw/i2c.c (revision 68396ea9)
1 /*
2  * QEMU I2C bus interface.
3  *
4  * Copyright (c) 2007 CodeSourcery.
5  * Written by Paul Brook
6  *
7  * This code is licenced under the LGPL.
8  */
9 
10 #include "i2c.h"
11 
12 struct i2c_bus
13 {
14     BusState qbus;
15     i2c_slave *current_dev;
16     i2c_slave *dev;
17     uint8_t saved_address;
18 };
19 
20 static struct BusInfo i2c_bus_info = {
21     .name = "I2C",
22     .size = sizeof(i2c_bus),
23     .props = (Property[]) {
24         DEFINE_PROP_UINT8("address", struct i2c_slave, address, 0),
25         DEFINE_PROP_END_OF_LIST(),
26     }
27 };
28 
i2c_bus_pre_save(void * opaque)29 static void i2c_bus_pre_save(void *opaque)
30 {
31     i2c_bus *bus = opaque;
32 
33     bus->saved_address = bus->current_dev ? bus->current_dev->address : -1;
34 }
35 
i2c_bus_post_load(void * opaque,int version_id)36 static int i2c_bus_post_load(void *opaque, int version_id)
37 {
38     i2c_bus *bus = opaque;
39 
40     /* The bus is loaded before attached devices, so load and save the
41        current device id.  Devices will check themselves as loaded.  */
42     bus->current_dev = NULL;
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     .minimum_version_id_old = 1,
51     .pre_save = i2c_bus_pre_save,
52     .post_load = i2c_bus_post_load,
53     .fields      = (VMStateField []) {
54         VMSTATE_UINT8(saved_address, i2c_bus),
55         VMSTATE_END_OF_LIST()
56     }
57 };
58 
59 /* Create a new I2C bus.  */
i2c_init_bus(DeviceState * parent,const char * name)60 i2c_bus *i2c_init_bus(DeviceState *parent, const char *name)
61 {
62     i2c_bus *bus;
63 
64     bus = FROM_QBUS(i2c_bus, qbus_create(&i2c_bus_info, parent, name));
65     vmstate_register(NULL, -1, &vmstate_i2c_bus, bus);
66     return bus;
67 }
68 
i2c_set_slave_address(i2c_slave * dev,uint8_t address)69 void i2c_set_slave_address(i2c_slave *dev, uint8_t address)
70 {
71     dev->address = address;
72 }
73 
74 /* Return nonzero if bus is busy.  */
i2c_bus_busy(i2c_bus * bus)75 int i2c_bus_busy(i2c_bus *bus)
76 {
77     return bus->current_dev != NULL;
78 }
79 
80 /* Returns non-zero if the address is not valid.  */
81 /* TODO: Make this handle multiple masters.  */
i2c_start_transfer(i2c_bus * bus,uint8_t address,int recv)82 int i2c_start_transfer(i2c_bus *bus, uint8_t address, int recv)
83 {
84     DeviceState *qdev;
85     i2c_slave *slave = NULL;
86 
87     QLIST_FOREACH(qdev, &bus->qbus.children, sibling) {
88         i2c_slave *candidate = I2C_SLAVE_FROM_QDEV(qdev);
89         if (candidate->address == address) {
90             slave = candidate;
91             break;
92         }
93     }
94 
95     if (!slave)
96         return 1;
97 
98     /* If the bus is already busy, assume this is a repeated
99        start condition.  */
100     bus->current_dev = slave;
101     slave->info->event(slave, recv ? I2C_START_RECV : I2C_START_SEND);
102     return 0;
103 }
104 
i2c_end_transfer(i2c_bus * bus)105 void i2c_end_transfer(i2c_bus *bus)
106 {
107     i2c_slave *dev = bus->current_dev;
108 
109     if (!dev)
110         return;
111 
112     dev->info->event(dev, I2C_FINISH);
113 
114     bus->current_dev = NULL;
115 }
116 
i2c_send(i2c_bus * bus,uint8_t data)117 int i2c_send(i2c_bus *bus, uint8_t data)
118 {
119     i2c_slave *dev = bus->current_dev;
120 
121     if (!dev)
122         return -1;
123 
124     return dev->info->send(dev, data);
125 }
126 
i2c_recv(i2c_bus * bus)127 int i2c_recv(i2c_bus *bus)
128 {
129     i2c_slave *dev = bus->current_dev;
130 
131     if (!dev)
132         return -1;
133 
134     return dev->info->recv(dev);
135 }
136 
i2c_nack(i2c_bus * bus)137 void i2c_nack(i2c_bus *bus)
138 {
139     i2c_slave *dev = bus->current_dev;
140 
141     if (!dev)
142         return;
143 
144     dev->info->event(dev, I2C_NACK);
145 }
146 
i2c_slave_post_load(void * opaque,int version_id)147 static int i2c_slave_post_load(void *opaque, int version_id)
148 {
149     i2c_slave *dev = opaque;
150     i2c_bus *bus;
151     bus = FROM_QBUS(i2c_bus, qdev_get_parent_bus(&dev->qdev));
152     if (bus->saved_address == dev->address) {
153         bus->current_dev = dev;
154     }
155     return 0;
156 }
157 
158 const VMStateDescription vmstate_i2c_slave = {
159     .name = "i2c_slave",
160     .version_id = 1,
161     .minimum_version_id = 1,
162     .minimum_version_id_old = 1,
163     .post_load = i2c_slave_post_load,
164     .fields      = (VMStateField []) {
165         VMSTATE_UINT8(address, i2c_slave),
166         VMSTATE_END_OF_LIST()
167     }
168 };
169 
i2c_slave_qdev_init(DeviceState * dev,DeviceInfo * base)170 static int i2c_slave_qdev_init(DeviceState *dev, DeviceInfo *base)
171 {
172     I2CSlaveInfo *info = container_of(base, I2CSlaveInfo, qdev);
173     i2c_slave *s = I2C_SLAVE_FROM_QDEV(dev);
174 
175     s->info = info;
176 
177     return info->init(s);
178 }
179 
i2c_register_slave(I2CSlaveInfo * info)180 void i2c_register_slave(I2CSlaveInfo *info)
181 {
182     assert(info->qdev.size >= sizeof(i2c_slave));
183     info->qdev.init = i2c_slave_qdev_init;
184     info->qdev.bus_info = &i2c_bus_info;
185     qdev_register(&info->qdev);
186 }
187 
i2c_create_slave(i2c_bus * bus,const char * name,uint8_t addr)188 DeviceState *i2c_create_slave(i2c_bus *bus, const char *name, uint8_t addr)
189 {
190     DeviceState *dev;
191 
192     dev = qdev_create(&bus->qbus, name);
193     qdev_prop_set_uint8(dev, "address", addr);
194     qdev_init_nofail(dev);
195     return dev;
196 }
197