1/* A simple I2C slave for returning monitor EDID data via DDC.
2 *
3 * Copyright (c) 2011 Linaro Limited
4 * Written by Peter Maydell
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, see <http://www.gnu.org/licenses/>.
17 */
18
19#include "qemu/osdep.h"
20#include "qemu/log.h"
21#include "qemu/module.h"
22#include "hw/i2c/i2c.h"
23#include "hw/qdev-properties.h"
24#include "migration/vmstate.h"
25#include "hw/display/i2c-ddc.h"
26
27#ifndef DEBUG_I2CDDC
28#define DEBUG_I2CDDC 0
29#endif
30
31#define DPRINTF(fmt, ...) do { \
32 if (DEBUG_I2CDDC) { \
33 qemu_log("i2c-ddc: " fmt , ## __VA_ARGS__); \
34 } \
35} while (0)
36
37static void i2c_ddc_reset(DeviceState *ds)
38{
39 I2CDDCState *s = I2CDDC(ds);
40
41 s->firstbyte = false;
42 s->reg = 0;
43}
44
45static int i2c_ddc_event(I2CSlave *i2c, enum i2c_event event)
46{
47 I2CDDCState *s = I2CDDC(i2c);
48
49 if (event == I2C_START_SEND) {
50 s->firstbyte = true;
51 }
52
53 return 0;
54}
55
56static uint8_t i2c_ddc_rx(I2CSlave *i2c)
57{
58 I2CDDCState *s = I2CDDC(i2c);
59
60 int value;
61 value = s->edid_blob[s->reg % sizeof(s->edid_blob)];
62 s->reg++;
63 return value;
64}
65
66static int i2c_ddc_tx(I2CSlave *i2c, uint8_t data)
67{
68 I2CDDCState *s = I2CDDC(i2c);
69 if (s->firstbyte) {
70 s->reg = data;
71 s->firstbyte = false;
72 DPRINTF("[EDID] Written new pointer: %u\n", data);
73 return 0;
74 }
75
76 /* Ignore all writes */
77 s->reg++;
78 return 0;
79}
80
81static void i2c_ddc_init(Object *obj)
82{
83 I2CDDCState *s = I2CDDC(obj);
84
85 qemu_edid_generate(s->edid_blob, sizeof(s->edid_blob), &s->edid_info);
86}
87
88static const VMStateDescription vmstate_i2c_ddc = {
89 .name = TYPE_I2CDDC,
90 .version_id = 1,
91 .fields = (VMStateField[]) {
92 VMSTATE_BOOL(firstbyte, I2CDDCState),
93 VMSTATE_UINT8(reg, I2CDDCState),
94 VMSTATE_END_OF_LIST()
95 }
96};
97
98static Property i2c_ddc_properties[] = {
99 DEFINE_EDID_PROPERTIES(I2CDDCState, edid_info),
100 DEFINE_PROP_END_OF_LIST(),
101};
102
103static void i2c_ddc_class_init(ObjectClass *oc, void *data)
104{
105 DeviceClass *dc = DEVICE_CLASS(oc);
106 I2CSlaveClass *isc = I2C_SLAVE_CLASS(oc);
107
108 dc->reset = i2c_ddc_reset;
109 dc->vmsd = &vmstate_i2c_ddc;
110 dc->props = i2c_ddc_properties;
111 isc->event = i2c_ddc_event;
112 isc->recv = i2c_ddc_rx;
113 isc->send = i2c_ddc_tx;
114}
115
116static TypeInfo i2c_ddc_info = {
117 .name = TYPE_I2CDDC,
118 .parent = TYPE_I2C_SLAVE,
119 .instance_size = sizeof(I2CDDCState),
120 .instance_init = i2c_ddc_init,
121 .class_init = i2c_ddc_class_init
122};
123
124static void ddc_register_devices(void)
125{
126 type_register_static(&i2c_ddc_info);
127}
128
129type_init(ddc_register_devices);
130