root / hw / i2c.c @ c75a823c
History | View | Annotate | Download (2.7 kB)
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 "hw.h" |
11 |
#include "i2c.h" |
12 |
|
13 |
struct i2c_bus
|
14 |
{ |
15 |
i2c_slave *current_dev; |
16 |
i2c_slave *dev; |
17 |
}; |
18 |
|
19 |
/* Create a new I2C bus. */
|
20 |
i2c_bus *i2c_init_bus(void)
|
21 |
{ |
22 |
i2c_bus *bus; |
23 |
|
24 |
bus = (i2c_bus *)qemu_mallocz(sizeof(i2c_bus));
|
25 |
return bus;
|
26 |
} |
27 |
|
28 |
/* Create a new slave device. */
|
29 |
i2c_slave *i2c_slave_init(i2c_bus *bus, int address, int size) |
30 |
{ |
31 |
i2c_slave *dev; |
32 |
|
33 |
if (size < sizeof(i2c_slave)) |
34 |
hw_error("I2C struct too small");
|
35 |
|
36 |
dev = (i2c_slave *)qemu_mallocz(size); |
37 |
dev->address = address; |
38 |
dev->next = bus->dev; |
39 |
bus->dev = dev; |
40 |
|
41 |
return dev;
|
42 |
} |
43 |
|
44 |
void i2c_set_slave_address(i2c_slave *dev, int address) |
45 |
{ |
46 |
dev->address = address; |
47 |
} |
48 |
|
49 |
/* Return nonzero if bus is busy. */
|
50 |
int i2c_bus_busy(i2c_bus *bus)
|
51 |
{ |
52 |
return bus->current_dev != NULL; |
53 |
} |
54 |
|
55 |
/* Returns non-zero if the address is not valid. */
|
56 |
/* TODO: Make this handle multiple masters. */
|
57 |
int i2c_start_transfer(i2c_bus *bus, int address, int recv) |
58 |
{ |
59 |
i2c_slave *dev; |
60 |
|
61 |
for (dev = bus->dev; dev; dev = dev->next) {
|
62 |
if (dev->address == address)
|
63 |
break;
|
64 |
} |
65 |
|
66 |
if (!dev)
|
67 |
return 1; |
68 |
|
69 |
/* If the bus is already busy, assume this is a repeated
|
70 |
start condition. */
|
71 |
bus->current_dev = dev; |
72 |
dev->event(dev, recv ? I2C_START_RECV : I2C_START_SEND); |
73 |
return 0; |
74 |
} |
75 |
|
76 |
void i2c_end_transfer(i2c_bus *bus)
|
77 |
{ |
78 |
i2c_slave *dev = bus->current_dev; |
79 |
|
80 |
if (!dev)
|
81 |
return;
|
82 |
|
83 |
dev->event(dev, I2C_FINISH); |
84 |
|
85 |
bus->current_dev = NULL;
|
86 |
} |
87 |
|
88 |
int i2c_send(i2c_bus *bus, uint8_t data)
|
89 |
{ |
90 |
i2c_slave *dev = bus->current_dev; |
91 |
|
92 |
if (!dev)
|
93 |
return -1; |
94 |
|
95 |
return dev->send(dev, data);
|
96 |
} |
97 |
|
98 |
int i2c_recv(i2c_bus *bus)
|
99 |
{ |
100 |
i2c_slave *dev = bus->current_dev; |
101 |
|
102 |
if (!dev)
|
103 |
return -1; |
104 |
|
105 |
return dev->recv(dev);
|
106 |
} |
107 |
|
108 |
void i2c_nack(i2c_bus *bus)
|
109 |
{ |
110 |
i2c_slave *dev = bus->current_dev; |
111 |
|
112 |
if (!dev)
|
113 |
return;
|
114 |
|
115 |
dev->event(dev, I2C_NACK); |
116 |
} |
117 |
|
118 |
void i2c_bus_save(QEMUFile *f, i2c_bus *bus)
|
119 |
{ |
120 |
qemu_put_byte(f, bus->current_dev ? bus->current_dev->address : 0x00);
|
121 |
} |
122 |
|
123 |
void i2c_bus_load(QEMUFile *f, i2c_bus *bus)
|
124 |
{ |
125 |
i2c_slave *dev; |
126 |
uint8_t address = qemu_get_byte(f); |
127 |
|
128 |
if (address) {
|
129 |
for (dev = bus->dev; dev; dev = dev->next)
|
130 |
if (dev->address == address) {
|
131 |
bus->current_dev = dev; |
132 |
return;
|
133 |
} |
134 |
|
135 |
fprintf(stderr, "%s: I2C slave with address %02x disappeared\n",
|
136 |
__FUNCTION__, address); |
137 |
} |
138 |
} |
139 |
|
140 |
void i2c_slave_save(QEMUFile *f, i2c_slave *dev)
|
141 |
{ |
142 |
qemu_put_byte(f, dev->address); |
143 |
} |
144 |
|
145 |
void i2c_slave_load(QEMUFile *f, i2c_slave *dev)
|
146 |
{ |
147 |
dev->address = qemu_get_byte(f); |
148 |
} |