LXR qemu/hw/display/i2c-ddc.c

   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/display/i2c-ddc.h"
  24
  25#ifndef DEBUG_I2CDDC
  26#define DEBUG_I2CDDC 0
  27#endif
  28
  29#define DPRINTF(fmt, ...) do {                                                 \
  30    if (DEBUG_I2CDDC) {                                                        \
  31        qemu_log("i2c-ddc: " fmt , ## __VA_ARGS__);                            \
  32    }                                                                          \
  33} while (0)
  34
  35static void i2c_ddc_reset(DeviceState *ds)
  36{
  37    I2CDDCState *s = I2CDDC(ds);
  38
  39    s->firstbyte = false;
  40    s->reg = 0;
  41}
  42
  43static int i2c_ddc_event(I2CSlave *i2c, enum i2c_event event)
  44{
  45    I2CDDCState *s = I2CDDC(i2c);
  46
  47    if (event == I2C_START_SEND) {
  48        s->firstbyte = true;
  49    }
  50
  51    return 0;
  52}
  53
  54static uint8_t i2c_ddc_rx(I2CSlave *i2c)
  55{
  56    I2CDDCState *s = I2CDDC(i2c);
  57
  58    int value;
  59    value = s->edid_blob[s->reg % sizeof(s->edid_blob)];
  60    s->reg++;
  61    return value;
  62}
  63
  64static int i2c_ddc_tx(I2CSlave *i2c, uint8_t data)
  65{
  66    I2CDDCState *s = I2CDDC(i2c);
  67    if (s->firstbyte) {
  68        s->reg = data;
  69        s->firstbyte = false;
  70        DPRINTF("[EDID] Written new pointer: %u\n", data);
  71        return 0;
  72    }
  73
  74    /* Ignore all writes */
  75    s->reg++;
  76    return 0;
  77}
  78
  79static void i2c_ddc_init(Object *obj)
  80{
  81    I2CDDCState *s = I2CDDC(obj);
  82
  83    qemu_edid_generate(s->edid_blob, sizeof(s->edid_blob), &s->edid_info);
  84}
  85
  86static const VMStateDescription vmstate_i2c_ddc = {
  87    .name = TYPE_I2CDDC,
  88    .version_id = 1,
  89    .fields = (VMStateField[]) {
  90        VMSTATE_BOOL(firstbyte, I2CDDCState),
  91        VMSTATE_UINT8(reg, I2CDDCState),
  92        VMSTATE_END_OF_LIST()
  93    }
  94};
  95
  96static Property i2c_ddc_properties[] = {
  97    DEFINE_EDID_PROPERTIES(I2CDDCState, edid_info),
  98    DEFINE_PROP_END_OF_LIST(),
  99};
 100
 101static void i2c_ddc_class_init(ObjectClass *oc, void *data)
 102{
 103    DeviceClass *dc = DEVICE_CLASS(oc);
 104    I2CSlaveClass *isc = I2C_SLAVE_CLASS(oc);
 105
 106    dc->reset = i2c_ddc_reset;
 107    dc->vmsd = &vmstate_i2c_ddc;
 108    dc->props = i2c_ddc_properties;
 109    isc->event = i2c_ddc_event;
 110    isc->recv = i2c_ddc_rx;
 111    isc->send = i2c_ddc_tx;
 112}
 113
 114static TypeInfo i2c_ddc_info = {
 115    .name = TYPE_I2CDDC,
 116    .parent = TYPE_I2C_SLAVE,
 117    .instance_size = sizeof(I2CDDCState),
 118    .instance_init = i2c_ddc_init,
 119    .class_init = i2c_ddc_class_init
 120};
 121
 122static void ddc_register_devices(void)
 123{
 124    type_register_static(&i2c_ddc_info);
 125}
 126
 127type_init(ddc_register_devices);
 128