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
i2c_ddc_reset(DeviceState * ds)37 static void i2c_ddc_reset(DeviceState *ds)
38 {
39 I2CDDCState *s = I2CDDC(ds);
40
41 s->firstbyte = false;
42 s->reg = 0;
43 }
44
i2c_ddc_event(I2CSlave * i2c,enum i2c_event event)45 static 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
i2c_ddc_rx(I2CSlave * i2c)56 static 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
i2c_ddc_tx(I2CSlave * i2c,uint8_t data)66 static 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
i2c_ddc_init(Object * obj)81 static 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
88 static const VMStateDescription vmstate_i2c_ddc = {
89 .name = TYPE_I2CDDC,
90 .version_id = 1,
91 .fields = (const VMStateField[]) {
92 VMSTATE_BOOL(firstbyte, I2CDDCState),
93 VMSTATE_UINT8(reg, I2CDDCState),
94 VMSTATE_END_OF_LIST()
95 }
96 };
97
98 static Property i2c_ddc_properties[] = {
99 DEFINE_EDID_PROPERTIES(I2CDDCState, edid_info),
100 DEFINE_PROP_END_OF_LIST(),
101 };
102
i2c_ddc_class_init(ObjectClass * oc,void * data)103 static 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 device_class_set_legacy_reset(dc, i2c_ddc_reset);
109 dc->vmsd = &vmstate_i2c_ddc;
110 device_class_set_props(dc, i2c_ddc_properties);
111 isc->event = i2c_ddc_event;
112 isc->recv = i2c_ddc_rx;
113 isc->send = i2c_ddc_tx;
114 }
115
116 static const 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
ddc_register_devices(void)124 static void ddc_register_devices(void)
125 {
126 type_register_static(&i2c_ddc_info);
127 }
128
129 type_init(ddc_register_devices);
130