qemu

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i2c-ddc.c (3336B)

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