root / hw / bitbang_i2c.c @ d8ed79ae
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1 | 3ead03bd | Andrzej Zaborowski | /*
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2 | 3ead03bd | Andrzej Zaborowski | * Bit-Bang i2c emulation extracted from
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3 | 3ead03bd | Andrzej Zaborowski | * Marvell MV88W8618 / Freecom MusicPal emulation.
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4 | 3ead03bd | Andrzej Zaborowski | *
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5 | 3ead03bd | Andrzej Zaborowski | * Copyright (c) 2008 Jan Kiszka
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6 | 3ead03bd | Andrzej Zaborowski | *
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7 | 3ead03bd | Andrzej Zaborowski | * This code is licenced under the GNU GPL v2.
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8 | 3ead03bd | Andrzej Zaborowski | */
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9 | 3ead03bd | Andrzej Zaborowski | #include "hw.h" |
10 | 3ead03bd | Andrzej Zaborowski | #include "i2c.h" |
11 | 3ead03bd | Andrzej Zaborowski | #include "sysbus.h" |
12 | 3ead03bd | Andrzej Zaborowski | |
13 | 3ead03bd | Andrzej Zaborowski | typedef enum bitbang_i2c_state { |
14 | 3ead03bd | Andrzej Zaborowski | STOPPED = 0,
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15 | 3ead03bd | Andrzej Zaborowski | INITIALIZING, |
16 | 3ead03bd | Andrzej Zaborowski | SENDING_BIT7, |
17 | 3ead03bd | Andrzej Zaborowski | SENDING_BIT6, |
18 | 3ead03bd | Andrzej Zaborowski | SENDING_BIT5, |
19 | 3ead03bd | Andrzej Zaborowski | SENDING_BIT4, |
20 | 3ead03bd | Andrzej Zaborowski | SENDING_BIT3, |
21 | 3ead03bd | Andrzej Zaborowski | SENDING_BIT2, |
22 | 3ead03bd | Andrzej Zaborowski | SENDING_BIT1, |
23 | 3ead03bd | Andrzej Zaborowski | SENDING_BIT0, |
24 | 3ead03bd | Andrzej Zaborowski | WAITING_FOR_ACK, |
25 | 3ead03bd | Andrzej Zaborowski | RECEIVING_BIT7, |
26 | 3ead03bd | Andrzej Zaborowski | RECEIVING_BIT6, |
27 | 3ead03bd | Andrzej Zaborowski | RECEIVING_BIT5, |
28 | 3ead03bd | Andrzej Zaborowski | RECEIVING_BIT4, |
29 | 3ead03bd | Andrzej Zaborowski | RECEIVING_BIT3, |
30 | 3ead03bd | Andrzej Zaborowski | RECEIVING_BIT2, |
31 | 3ead03bd | Andrzej Zaborowski | RECEIVING_BIT1, |
32 | 3ead03bd | Andrzej Zaborowski | RECEIVING_BIT0, |
33 | 3ead03bd | Andrzej Zaborowski | SENDING_ACK |
34 | 3ead03bd | Andrzej Zaborowski | } bitbang_i2c_state; |
35 | 3ead03bd | Andrzej Zaborowski | |
36 | 3ead03bd | Andrzej Zaborowski | typedef struct bitbang_i2c_interface { |
37 | 3ead03bd | Andrzej Zaborowski | SysBusDevice busdev; |
38 | 3ead03bd | Andrzej Zaborowski | i2c_bus *bus; |
39 | 3ead03bd | Andrzej Zaborowski | bitbang_i2c_state state; |
40 | 3ead03bd | Andrzej Zaborowski | int last_data;
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41 | 3ead03bd | Andrzej Zaborowski | int last_clock;
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42 | 3ead03bd | Andrzej Zaborowski | uint8_t buffer; |
43 | 3ead03bd | Andrzej Zaborowski | int current_addr;
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44 | 3ead03bd | Andrzej Zaborowski | qemu_irq out; |
45 | 3ead03bd | Andrzej Zaborowski | } bitbang_i2c_interface; |
46 | 3ead03bd | Andrzej Zaborowski | |
47 | 3ead03bd | Andrzej Zaborowski | static void bitbang_i2c_enter_stop(bitbang_i2c_interface *i2c) |
48 | 3ead03bd | Andrzej Zaborowski | { |
49 | 3ead03bd | Andrzej Zaborowski | if (i2c->current_addr >= 0) |
50 | 3ead03bd | Andrzej Zaborowski | i2c_end_transfer(i2c->bus); |
51 | 3ead03bd | Andrzej Zaborowski | i2c->current_addr = -1;
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52 | 3ead03bd | Andrzej Zaborowski | i2c->state = STOPPED; |
53 | 3ead03bd | Andrzej Zaborowski | } |
54 | 3ead03bd | Andrzej Zaborowski | |
55 | 3ead03bd | Andrzej Zaborowski | static void bitbang_i2c_gpio_set(void *opaque, int irq, int level) |
56 | 3ead03bd | Andrzej Zaborowski | { |
57 | 3ead03bd | Andrzej Zaborowski | bitbang_i2c_interface *i2c = opaque; |
58 | 3ead03bd | Andrzej Zaborowski | int data;
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59 | 3ead03bd | Andrzej Zaborowski | int clock;
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60 | 3ead03bd | Andrzej Zaborowski | int data_goes_up;
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61 | 3ead03bd | Andrzej Zaborowski | int data_goes_down;
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62 | 3ead03bd | Andrzej Zaborowski | int clock_goes_up;
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63 | 3ead03bd | Andrzej Zaborowski | int clock_goes_down;
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64 | 3ead03bd | Andrzej Zaborowski | |
65 | 3ead03bd | Andrzej Zaborowski | /* get pins states */
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66 | 3ead03bd | Andrzej Zaborowski | data = i2c->last_data; |
67 | 3ead03bd | Andrzej Zaborowski | clock = i2c->last_clock; |
68 | 3ead03bd | Andrzej Zaborowski | |
69 | 3ead03bd | Andrzej Zaborowski | if (irq == 0) |
70 | 3ead03bd | Andrzej Zaborowski | data = level; |
71 | 3ead03bd | Andrzej Zaborowski | if (irq == 1) |
72 | 3ead03bd | Andrzej Zaborowski | clock = level; |
73 | 3ead03bd | Andrzej Zaborowski | |
74 | 3ead03bd | Andrzej Zaborowski | /* compute pins changes */
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75 | 3ead03bd | Andrzej Zaborowski | data_goes_up = data == 1 && i2c->last_data == 0; |
76 | 3ead03bd | Andrzej Zaborowski | data_goes_down = data == 0 && i2c->last_data == 1; |
77 | 3ead03bd | Andrzej Zaborowski | clock_goes_up = clock == 1 && i2c->last_clock == 0; |
78 | 3ead03bd | Andrzej Zaborowski | clock_goes_down = clock == 0 && i2c->last_clock == 1; |
79 | 3ead03bd | Andrzej Zaborowski | |
80 | 3ead03bd | Andrzej Zaborowski | if (data_goes_up == 0 && data_goes_down == 0 && |
81 | 3ead03bd | Andrzej Zaborowski | clock_goes_up == 0 && clock_goes_down == 0) |
82 | 3ead03bd | Andrzej Zaborowski | return;
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83 | 3ead03bd | Andrzej Zaborowski | |
84 | 3ead03bd | Andrzej Zaborowski | if (!i2c)
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85 | 3ead03bd | Andrzej Zaborowski | return;
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86 | 3ead03bd | Andrzej Zaborowski | |
87 | 3ead03bd | Andrzej Zaborowski | if ((RECEIVING_BIT7 > i2c->state && i2c->state > RECEIVING_BIT0)
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88 | 3ead03bd | Andrzej Zaborowski | || i2c->state == WAITING_FOR_ACK) |
89 | 3ead03bd | Andrzej Zaborowski | qemu_set_irq(i2c->out, 0);
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90 | 3ead03bd | Andrzej Zaborowski | |
91 | 3ead03bd | Andrzej Zaborowski | switch (i2c->state) {
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92 | 3ead03bd | Andrzej Zaborowski | case STOPPED:
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93 | 3ead03bd | Andrzej Zaborowski | if (data_goes_down && clock == 1) |
94 | 3ead03bd | Andrzej Zaborowski | i2c->state = INITIALIZING; |
95 | 3ead03bd | Andrzej Zaborowski | break;
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96 | 3ead03bd | Andrzej Zaborowski | |
97 | 3ead03bd | Andrzej Zaborowski | case INITIALIZING:
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98 | 3ead03bd | Andrzej Zaborowski | if (clock_goes_down && data == 0) |
99 | 3ead03bd | Andrzej Zaborowski | i2c->state = SENDING_BIT7; |
100 | 3ead03bd | Andrzej Zaborowski | else
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101 | 3ead03bd | Andrzej Zaborowski | bitbang_i2c_enter_stop(i2c); |
102 | 3ead03bd | Andrzej Zaborowski | break;
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103 | 3ead03bd | Andrzej Zaborowski | |
104 | 3ead03bd | Andrzej Zaborowski | case SENDING_BIT7 ... SENDING_BIT0:
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105 | 3ead03bd | Andrzej Zaborowski | if (clock_goes_down) {
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106 | 3ead03bd | Andrzej Zaborowski | i2c->buffer = (i2c->buffer << 1) | data;
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107 | 3ead03bd | Andrzej Zaborowski | /* will end up in WAITING_FOR_ACK */
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108 | 3ead03bd | Andrzej Zaborowski | i2c->state++; |
109 | 3ead03bd | Andrzej Zaborowski | } else if (data_goes_up && clock == 1) |
110 | 3ead03bd | Andrzej Zaborowski | bitbang_i2c_enter_stop(i2c); |
111 | 3ead03bd | Andrzej Zaborowski | break;
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112 | 3ead03bd | Andrzej Zaborowski | |
113 | 3ead03bd | Andrzej Zaborowski | case WAITING_FOR_ACK:
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114 | 3ead03bd | Andrzej Zaborowski | if (clock_goes_down) {
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115 | 3ead03bd | Andrzej Zaborowski | if (i2c->current_addr < 0) { |
116 | 3ead03bd | Andrzej Zaborowski | i2c->current_addr = i2c->buffer; |
117 | 3ead03bd | Andrzej Zaborowski | i2c_start_transfer(i2c->bus, (i2c->current_addr & 0xfe) / 2, |
118 | 3ead03bd | Andrzej Zaborowski | i2c->buffer & 1);
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119 | 3ead03bd | Andrzej Zaborowski | } else
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120 | 3ead03bd | Andrzej Zaborowski | i2c_send(i2c->bus, i2c->buffer); |
121 | 3ead03bd | Andrzej Zaborowski | if (i2c->current_addr & 1) { |
122 | 3ead03bd | Andrzej Zaborowski | i2c->state = RECEIVING_BIT7; |
123 | 3ead03bd | Andrzej Zaborowski | i2c->buffer = i2c_recv(i2c->bus); |
124 | 3ead03bd | Andrzej Zaborowski | } else
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125 | 3ead03bd | Andrzej Zaborowski | i2c->state = SENDING_BIT7; |
126 | 3ead03bd | Andrzej Zaborowski | } else if (data_goes_up && clock == 1) |
127 | 3ead03bd | Andrzej Zaborowski | bitbang_i2c_enter_stop(i2c); |
128 | 3ead03bd | Andrzej Zaborowski | break;
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129 | 3ead03bd | Andrzej Zaborowski | |
130 | 3ead03bd | Andrzej Zaborowski | case RECEIVING_BIT7 ... RECEIVING_BIT0:
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131 | 3ead03bd | Andrzej Zaborowski | qemu_set_irq(i2c->out, i2c->buffer >> 7);
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132 | 3ead03bd | Andrzej Zaborowski | if (clock_goes_down) {
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133 | 3ead03bd | Andrzej Zaborowski | /* will end up in SENDING_ACK */
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134 | 3ead03bd | Andrzej Zaborowski | i2c->state++; |
135 | 3ead03bd | Andrzej Zaborowski | i2c->buffer <<= 1;
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136 | 3ead03bd | Andrzej Zaborowski | } else if (data_goes_up && clock == 1) |
137 | 3ead03bd | Andrzej Zaborowski | bitbang_i2c_enter_stop(i2c); |
138 | 3ead03bd | Andrzej Zaborowski | break;
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139 | 3ead03bd | Andrzej Zaborowski | |
140 | 3ead03bd | Andrzej Zaborowski | case SENDING_ACK:
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141 | 3ead03bd | Andrzej Zaborowski | if (clock_goes_down) {
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142 | 3ead03bd | Andrzej Zaborowski | i2c->state = RECEIVING_BIT7; |
143 | 3ead03bd | Andrzej Zaborowski | if (data == 0) |
144 | 3ead03bd | Andrzej Zaborowski | i2c->buffer = i2c_recv(i2c->bus); |
145 | 3ead03bd | Andrzej Zaborowski | else
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146 | 3ead03bd | Andrzej Zaborowski | i2c_nack(i2c->bus); |
147 | 3ead03bd | Andrzej Zaborowski | } else if (data_goes_up && clock == 1) |
148 | 3ead03bd | Andrzej Zaborowski | bitbang_i2c_enter_stop(i2c); |
149 | 3ead03bd | Andrzej Zaborowski | break;
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150 | 3ead03bd | Andrzej Zaborowski | } |
151 | 3ead03bd | Andrzej Zaborowski | |
152 | 3ead03bd | Andrzej Zaborowski | i2c->last_data = data; |
153 | 3ead03bd | Andrzej Zaborowski | i2c->last_clock = clock; |
154 | 3ead03bd | Andrzej Zaborowski | } |
155 | 3ead03bd | Andrzej Zaborowski | |
156 | 81a322d4 | Gerd Hoffmann | static int bitbang_i2c_init(SysBusDevice *dev) |
157 | 3ead03bd | Andrzej Zaborowski | { |
158 | 3ead03bd | Andrzej Zaborowski | bitbang_i2c_interface *s = FROM_SYSBUS(bitbang_i2c_interface, dev); |
159 | 3ead03bd | Andrzej Zaborowski | i2c_bus *bus; |
160 | 3ead03bd | Andrzej Zaborowski | |
161 | 3ead03bd | Andrzej Zaborowski | sysbus_init_mmio(dev, 0x0, 0); |
162 | 3ead03bd | Andrzej Zaborowski | |
163 | 3ead03bd | Andrzej Zaborowski | bus = i2c_init_bus(&dev->qdev, "i2c");
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164 | 3ead03bd | Andrzej Zaborowski | s->bus = bus; |
165 | 3ead03bd | Andrzej Zaborowski | |
166 | 3ead03bd | Andrzej Zaborowski | s->last_data = 1;
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167 | 3ead03bd | Andrzej Zaborowski | s->last_clock = 1;
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168 | 3ead03bd | Andrzej Zaborowski | |
169 | 3ead03bd | Andrzej Zaborowski | qdev_init_gpio_in(&dev->qdev, bitbang_i2c_gpio_set, 2);
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170 | 3ead03bd | Andrzej Zaborowski | qdev_init_gpio_out(&dev->qdev, &s->out, 1);
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171 | 81a322d4 | Gerd Hoffmann | |
172 | 81a322d4 | Gerd Hoffmann | return 0; |
173 | 3ead03bd | Andrzej Zaborowski | } |
174 | 3ead03bd | Andrzej Zaborowski | |
175 | 3ead03bd | Andrzej Zaborowski | static void bitbang_i2c_register(void) |
176 | 3ead03bd | Andrzej Zaborowski | { |
177 | 3ead03bd | Andrzej Zaborowski | sysbus_register_dev("bitbang_i2c",
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178 | 3ead03bd | Andrzej Zaborowski | sizeof(bitbang_i2c_interface), bitbang_i2c_init);
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179 | 3ead03bd | Andrzej Zaborowski | } |
180 | 3ead03bd | Andrzej Zaborowski | |
181 | 3ead03bd | Andrzej Zaborowski | device_init(bitbang_i2c_register) |