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3ead03bd AZ |
1 | /* |
2 | * Bit-Bang i2c emulation extracted from | |
3 | * Marvell MV88W8618 / Freecom MusicPal emulation. | |
4 | * | |
5 | * Copyright (c) 2008 Jan Kiszka | |
6 | * | |
8e31bf38 | 7 | * This code is licensed under the GNU GPL v2. |
6b620ca3 PB |
8 | * |
9 | * Contributions after 2012-01-13 are licensed under the terms of the | |
10 | * GNU GPL, version 2 or (at your option) any later version. | |
3ead03bd | 11 | */ |
0430891c | 12 | #include "qemu/osdep.h" |
83c9f4ca | 13 | #include "hw/hw.h" |
47b43a1f | 14 | #include "bitbang_i2c.h" |
83c9f4ca | 15 | #include "hw/sysbus.h" |
3ead03bd | 16 | |
3cd035d8 PB |
17 | //#define DEBUG_BITBANG_I2C |
18 | ||
19 | #ifdef DEBUG_BITBANG_I2C | |
20 | #define DPRINTF(fmt, ...) \ | |
21 | do { printf("bitbang_i2c: " fmt , ## __VA_ARGS__); } while (0) | |
22 | #else | |
23 | #define DPRINTF(fmt, ...) do {} while(0) | |
24 | #endif | |
25 | ||
3ead03bd AZ |
26 | typedef enum bitbang_i2c_state { |
27 | STOPPED = 0, | |
3ead03bd AZ |
28 | SENDING_BIT7, |
29 | SENDING_BIT6, | |
30 | SENDING_BIT5, | |
31 | SENDING_BIT4, | |
32 | SENDING_BIT3, | |
33 | SENDING_BIT2, | |
34 | SENDING_BIT1, | |
35 | SENDING_BIT0, | |
36 | WAITING_FOR_ACK, | |
37 | RECEIVING_BIT7, | |
38 | RECEIVING_BIT6, | |
39 | RECEIVING_BIT5, | |
40 | RECEIVING_BIT4, | |
41 | RECEIVING_BIT3, | |
42 | RECEIVING_BIT2, | |
43 | RECEIVING_BIT1, | |
44 | RECEIVING_BIT0, | |
2eb9f241 MC |
45 | SENDING_ACK, |
46 | SENT_NACK | |
3ead03bd AZ |
47 | } bitbang_i2c_state; |
48 | ||
3cd035d8 | 49 | struct bitbang_i2c_interface { |
a5c82852 | 50 | I2CBus *bus; |
3ead03bd AZ |
51 | bitbang_i2c_state state; |
52 | int last_data; | |
53 | int last_clock; | |
3cd035d8 | 54 | int device_out; |
3ead03bd AZ |
55 | uint8_t buffer; |
56 | int current_addr; | |
3cd035d8 | 57 | }; |
3ead03bd AZ |
58 | |
59 | static void bitbang_i2c_enter_stop(bitbang_i2c_interface *i2c) | |
60 | { | |
3cd035d8 | 61 | DPRINTF("STOP\n"); |
3ead03bd AZ |
62 | if (i2c->current_addr >= 0) |
63 | i2c_end_transfer(i2c->bus); | |
64 | i2c->current_addr = -1; | |
65 | i2c->state = STOPPED; | |
66 | } | |
67 | ||
3cd035d8 PB |
68 | /* Set device data pin. */ |
69 | static int bitbang_i2c_ret(bitbang_i2c_interface *i2c, int level) | |
70 | { | |
71 | i2c->device_out = level; | |
72 | //DPRINTF("%d %d %d\n", i2c->last_clock, i2c->last_data, i2c->device_out); | |
73 | return level & i2c->last_data; | |
74 | } | |
75 | ||
76 | /* Leave device data pin unodified. */ | |
77 | static int bitbang_i2c_nop(bitbang_i2c_interface *i2c) | |
78 | { | |
79 | return bitbang_i2c_ret(i2c, i2c->device_out); | |
80 | } | |
81 | ||
82 | /* Returns data line level. */ | |
83 | int bitbang_i2c_set(bitbang_i2c_interface *i2c, int line, int level) | |
3ead03bd | 84 | { |
3ead03bd | 85 | int data; |
3ead03bd | 86 | |
3cd035d8 PB |
87 | if (level != 0 && level != 1) { |
88 | abort(); | |
89 | } | |
3ead03bd | 90 | |
3cd035d8 PB |
91 | if (line == BITBANG_I2C_SDA) { |
92 | if (level == i2c->last_data) { | |
93 | return bitbang_i2c_nop(i2c); | |
94 | } | |
95 | i2c->last_data = level; | |
96 | if (i2c->last_clock == 0) { | |
97 | return bitbang_i2c_nop(i2c); | |
98 | } | |
99 | if (level == 0) { | |
100 | DPRINTF("START\n"); | |
101 | /* START condition. */ | |
3ead03bd | 102 | i2c->state = SENDING_BIT7; |
3cd035d8 PB |
103 | i2c->current_addr = -1; |
104 | } else { | |
105 | /* STOP condition. */ | |
3ead03bd | 106 | bitbang_i2c_enter_stop(i2c); |
3cd035d8 PB |
107 | } |
108 | return bitbang_i2c_ret(i2c, 1); | |
109 | } | |
110 | ||
111 | data = i2c->last_data; | |
112 | if (i2c->last_clock == level) { | |
113 | return bitbang_i2c_nop(i2c); | |
114 | } | |
115 | i2c->last_clock = level; | |
116 | if (level == 0) { | |
117 | /* State is set/read at the start of the clock pulse. | |
118 | release the data line at the end. */ | |
119 | return bitbang_i2c_ret(i2c, 1); | |
120 | } | |
121 | switch (i2c->state) { | |
122 | case STOPPED: | |
2eb9f241 | 123 | case SENT_NACK: |
3cd035d8 | 124 | return bitbang_i2c_ret(i2c, 1); |
3ead03bd AZ |
125 | |
126 | case SENDING_BIT7 ... SENDING_BIT0: | |
3cd035d8 PB |
127 | i2c->buffer = (i2c->buffer << 1) | data; |
128 | /* will end up in WAITING_FOR_ACK */ | |
129 | i2c->state++; | |
130 | return bitbang_i2c_ret(i2c, 1); | |
3ead03bd AZ |
131 | |
132 | case WAITING_FOR_ACK: | |
3cd035d8 PB |
133 | if (i2c->current_addr < 0) { |
134 | i2c->current_addr = i2c->buffer; | |
135 | DPRINTF("Address 0x%02x\n", i2c->current_addr); | |
136 | i2c_start_transfer(i2c->bus, i2c->current_addr >> 1, | |
137 | i2c->current_addr & 1); | |
138 | } else { | |
139 | DPRINTF("Sent 0x%02x\n", i2c->buffer); | |
140 | i2c_send(i2c->bus, i2c->buffer); | |
141 | } | |
142 | if (i2c->current_addr & 1) { | |
143 | i2c->state = RECEIVING_BIT7; | |
144 | } else { | |
145 | i2c->state = SENDING_BIT7; | |
146 | } | |
147 | return bitbang_i2c_ret(i2c, 0); | |
148 | ||
149 | case RECEIVING_BIT7: | |
150 | i2c->buffer = i2c_recv(i2c->bus); | |
151 | DPRINTF("RX byte 0x%02x\n", i2c->buffer); | |
152 | /* Fall through... */ | |
153 | case RECEIVING_BIT6 ... RECEIVING_BIT0: | |
154 | data = i2c->buffer >> 7; | |
155 | /* will end up in SENDING_ACK */ | |
156 | i2c->state++; | |
157 | i2c->buffer <<= 1; | |
158 | return bitbang_i2c_ret(i2c, data); | |
3ead03bd AZ |
159 | |
160 | case SENDING_ACK: | |
3cd035d8 PB |
161 | i2c->state = RECEIVING_BIT7; |
162 | if (data != 0) { | |
163 | DPRINTF("NACKED\n"); | |
2eb9f241 | 164 | i2c->state = SENT_NACK; |
3cd035d8 PB |
165 | i2c_nack(i2c->bus); |
166 | } else { | |
167 | DPRINTF("ACKED\n"); | |
168 | } | |
169 | return bitbang_i2c_ret(i2c, 1); | |
3ead03bd | 170 | } |
3cd035d8 PB |
171 | abort(); |
172 | } | |
173 | ||
a5c82852 | 174 | bitbang_i2c_interface *bitbang_i2c_init(I2CBus *bus) |
3cd035d8 PB |
175 | { |
176 | bitbang_i2c_interface *s; | |
177 | ||
7267c094 | 178 | s = g_malloc0(sizeof(bitbang_i2c_interface)); |
3cd035d8 PB |
179 | |
180 | s->bus = bus; | |
181 | s->last_data = 1; | |
182 | s->last_clock = 1; | |
183 | s->device_out = 1; | |
184 | ||
185 | return s; | |
186 | } | |
3ead03bd | 187 | |
3cd035d8 | 188 | /* GPIO interface. */ |
cc3c3b8a AF |
189 | |
190 | #define TYPE_GPIO_I2C "gpio_i2c" | |
191 | #define GPIO_I2C(obj) OBJECT_CHECK(GPIOI2CState, (obj), TYPE_GPIO_I2C) | |
192 | ||
193 | typedef struct GPIOI2CState { | |
194 | SysBusDevice parent_obj; | |
195 | ||
cffac71b | 196 | MemoryRegion dummy_iomem; |
3cd035d8 PB |
197 | bitbang_i2c_interface *bitbang; |
198 | int last_level; | |
199 | qemu_irq out; | |
200 | } GPIOI2CState; | |
201 | ||
202 | static void bitbang_i2c_gpio_set(void *opaque, int irq, int level) | |
203 | { | |
204 | GPIOI2CState *s = opaque; | |
205 | ||
206 | level = bitbang_i2c_set(s->bitbang, irq, level); | |
207 | if (level != s->last_level) { | |
208 | s->last_level = level; | |
209 | qemu_set_irq(s->out, level); | |
210 | } | |
3ead03bd AZ |
211 | } |
212 | ||
cc3c3b8a | 213 | static int gpio_i2c_init(SysBusDevice *sbd) |
3ead03bd | 214 | { |
cc3c3b8a AF |
215 | DeviceState *dev = DEVICE(sbd); |
216 | GPIOI2CState *s = GPIO_I2C(dev); | |
a5c82852 | 217 | I2CBus *bus; |
3ead03bd | 218 | |
1437c94b | 219 | memory_region_init(&s->dummy_iomem, OBJECT(s), "gpio_i2c", 0); |
cc3c3b8a | 220 | sysbus_init_mmio(sbd, &s->dummy_iomem); |
3ead03bd | 221 | |
cc3c3b8a | 222 | bus = i2c_init_bus(dev, "i2c"); |
3cd035d8 | 223 | s->bitbang = bitbang_i2c_init(bus); |
3ead03bd | 224 | |
cc3c3b8a AF |
225 | qdev_init_gpio_in(dev, bitbang_i2c_gpio_set, 2); |
226 | qdev_init_gpio_out(dev, &s->out, 1); | |
81a322d4 GH |
227 | |
228 | return 0; | |
3ead03bd AZ |
229 | } |
230 | ||
999e12bb AL |
231 | static void gpio_i2c_class_init(ObjectClass *klass, void *data) |
232 | { | |
39bffca2 | 233 | DeviceClass *dc = DEVICE_CLASS(klass); |
999e12bb AL |
234 | SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass); |
235 | ||
236 | k->init = gpio_i2c_init; | |
125ee0ed | 237 | set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories); |
39bffca2 | 238 | dc->desc = "Virtual GPIO to I2C bridge"; |
999e12bb AL |
239 | } |
240 | ||
8c43a6f0 | 241 | static const TypeInfo gpio_i2c_info = { |
cc3c3b8a | 242 | .name = TYPE_GPIO_I2C, |
39bffca2 AL |
243 | .parent = TYPE_SYS_BUS_DEVICE, |
244 | .instance_size = sizeof(GPIOI2CState), | |
245 | .class_init = gpio_i2c_class_init, | |
3cd035d8 PB |
246 | }; |
247 | ||
83f7d43a | 248 | static void bitbang_i2c_register_types(void) |
3ead03bd | 249 | { |
39bffca2 | 250 | type_register_static(&gpio_i2c_info); |
3ead03bd AZ |
251 | } |
252 | ||
83f7d43a | 253 | type_init(bitbang_i2c_register_types) |