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/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    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
 116static 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
 124static void ddc_register_devices(void)
 125{
 126    type_register_static(&i2c_ddc_info);
 127}
 128
 129type_init(ddc_register_devices);
 130