1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
|
/*
* Bit-Bang i2c emulation extracted from
* Marvell MV88W8618 / Freecom MusicPal emulation.
*
* Copyright (c) 2008 Jan Kiszka
*
* This code is licensed under the GNU GPL v2.
*
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
#include "hw.h"
#include "bitbang_i2c.h"
#include "sysbus.h"
//#define DEBUG_BITBANG_I2C
#ifdef DEBUG_BITBANG_I2C
#define DPRINTF(fmt, ...) \
do { printf("bitbang_i2c: " fmt , ## __VA_ARGS__); } while (0)
#else
#define DPRINTF(fmt, ...) do {} while(0)
#endif
typedef enum bitbang_i2c_state {
STOPPED = 0,
SENDING_BIT7,
SENDING_BIT6,
SENDING_BIT5,
SENDING_BIT4,
SENDING_BIT3,
SENDING_BIT2,
SENDING_BIT1,
SENDING_BIT0,
WAITING_FOR_ACK,
RECEIVING_BIT7,
RECEIVING_BIT6,
RECEIVING_BIT5,
RECEIVING_BIT4,
RECEIVING_BIT3,
RECEIVING_BIT2,
RECEIVING_BIT1,
RECEIVING_BIT0,
SENDING_ACK,
SENT_NACK
} bitbang_i2c_state;
struct bitbang_i2c_interface {
i2c_bus *bus;
bitbang_i2c_state state;
int last_data;
int last_clock;
int device_out;
uint8_t buffer;
int current_addr;
};
static void bitbang_i2c_enter_stop(bitbang_i2c_interface *i2c)
{
DPRINTF("STOP\n");
if (i2c->current_addr >= 0)
i2c_end_transfer(i2c->bus);
i2c->current_addr = -1;
i2c->state = STOPPED;
}
/* Set device data pin. */
static int bitbang_i2c_ret(bitbang_i2c_interface *i2c, int level)
{
i2c->device_out = level;
//DPRINTF("%d %d %d\n", i2c->last_clock, i2c->last_data, i2c->device_out);
return level & i2c->last_data;
}
/* Leave device data pin unodified. */
static int bitbang_i2c_nop(bitbang_i2c_interface *i2c)
{
return bitbang_i2c_ret(i2c, i2c->device_out);
}
/* Returns data line level. */
int bitbang_i2c_set(bitbang_i2c_interface *i2c, int line, int level)
{
int data;
if (level != 0 && level != 1) {
abort();
}
if (line == BITBANG_I2C_SDA) {
if (level == i2c->last_data) {
return bitbang_i2c_nop(i2c);
}
i2c->last_data = level;
if (i2c->last_clock == 0) {
return bitbang_i2c_nop(i2c);
}
if (level == 0) {
DPRINTF("START\n");
/* START condition. */
i2c->state = SENDING_BIT7;
i2c->current_addr = -1;
} else {
/* STOP condition. */
bitbang_i2c_enter_stop(i2c);
}
return bitbang_i2c_ret(i2c, 1);
}
data = i2c->last_data;
if (i2c->last_clock == level) {
return bitbang_i2c_nop(i2c);
}
i2c->last_clock = level;
if (level == 0) {
/* State is set/read at the start of the clock pulse.
release the data line at the end. */
return bitbang_i2c_ret(i2c, 1);
}
switch (i2c->state) {
case STOPPED:
case SENT_NACK:
return bitbang_i2c_ret(i2c, 1);
case SENDING_BIT7 ... SENDING_BIT0:
i2c->buffer = (i2c->buffer << 1) | data;
/* will end up in WAITING_FOR_ACK */
i2c->state++;
return bitbang_i2c_ret(i2c, 1);
case WAITING_FOR_ACK:
if (i2c->current_addr < 0) {
i2c->current_addr = i2c->buffer;
DPRINTF("Address 0x%02x\n", i2c->current_addr);
i2c_start_transfer(i2c->bus, i2c->current_addr >> 1,
i2c->current_addr & 1);
} else {
DPRINTF("Sent 0x%02x\n", i2c->buffer);
i2c_send(i2c->bus, i2c->buffer);
}
if (i2c->current_addr & 1) {
i2c->state = RECEIVING_BIT7;
} else {
i2c->state = SENDING_BIT7;
}
return bitbang_i2c_ret(i2c, 0);
case RECEIVING_BIT7:
i2c->buffer = i2c_recv(i2c->bus);
DPRINTF("RX byte 0x%02x\n", i2c->buffer);
/* Fall through... */
case RECEIVING_BIT6 ... RECEIVING_BIT0:
data = i2c->buffer >> 7;
/* will end up in SENDING_ACK */
i2c->state++;
i2c->buffer <<= 1;
return bitbang_i2c_ret(i2c, data);
case SENDING_ACK:
i2c->state = RECEIVING_BIT7;
if (data != 0) {
DPRINTF("NACKED\n");
i2c->state = SENT_NACK;
i2c_nack(i2c->bus);
} else {
DPRINTF("ACKED\n");
}
return bitbang_i2c_ret(i2c, 1);
}
abort();
}
bitbang_i2c_interface *bitbang_i2c_init(i2c_bus *bus)
{
bitbang_i2c_interface *s;
s = g_malloc0(sizeof(bitbang_i2c_interface));
s->bus = bus;
s->last_data = 1;
s->last_clock = 1;
s->device_out = 1;
return s;
}
/* GPIO interface. */
typedef struct {
SysBusDevice busdev;
MemoryRegion dummy_iomem;
bitbang_i2c_interface *bitbang;
int last_level;
qemu_irq out;
} GPIOI2CState;
static void bitbang_i2c_gpio_set(void *opaque, int irq, int level)
{
GPIOI2CState *s = opaque;
level = bitbang_i2c_set(s->bitbang, irq, level);
if (level != s->last_level) {
s->last_level = level;
qemu_set_irq(s->out, level);
}
}
static int gpio_i2c_init(SysBusDevice *dev)
{
GPIOI2CState *s = FROM_SYSBUS(GPIOI2CState, dev);
i2c_bus *bus;
memory_region_init(&s->dummy_iomem, "gpio_i2c", 0);
sysbus_init_mmio(dev, &s->dummy_iomem);
bus = i2c_init_bus(&dev->qdev, "i2c");
s->bitbang = bitbang_i2c_init(bus);
qdev_init_gpio_in(&dev->qdev, bitbang_i2c_gpio_set, 2);
qdev_init_gpio_out(&dev->qdev, &s->out, 1);
return 0;
}
static void gpio_i2c_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
k->init = gpio_i2c_init;
dc->desc = "Virtual GPIO to I2C bridge";
}
static TypeInfo gpio_i2c_info = {
.name = "gpio_i2c",
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(GPIOI2CState),
.class_init = gpio_i2c_class_init,
};
static void bitbang_i2c_register(void)
{
type_register_static(&gpio_i2c_info);
}
device_init(bitbang_i2c_register)
|
