hw/i2c/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-common.h"
  21 #include "qemu/log.h"
  22 #include "hw/i2c/i2c.h"
  23 #include "hw/i2c/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
  35 /* Structure defining a monitor's characteristics in a
  36  * readable format: this should be passed to build_edid_blob()
  37  * to convert it into the 128 byte binary EDID blob.
  38  * Not all bits of the EDID are customisable here.
  39  */
  40 struct EDIDData {
  41     char manuf_id[3]; /* three upper case letters */
  42     uint16_t product_id;
  43     uint32_t serial_no;
  44     uint8_t manuf_week;
  45     int manuf_year;
  46     uint8_t h_cm;
  47     uint8_t v_cm;
  48     uint8_t gamma;
  49     char monitor_name[14];
  50     char serial_no_string[14];
  51     /* Range limits */
  52     uint8_t vmin; /* Hz */
  53     uint8_t vmax; /* Hz */
  54     uint8_t hmin; /* kHz */
  55     uint8_t hmax; /* kHz */
  56     uint8_t pixclock; /* MHz / 10 */
  57     uint8_t timing_data[18];
  58 };
  59
  60 typedef struct EDIDData EDIDData;
  61
  62 /* EDID data for a simple LCD monitor */
  63 static const EDIDData lcd_edid = {
  64     /* The manuf_id ought really to be an assigned EISA ID */
  65     .manuf_id = "QMU",
  66     .product_id = 0,
  67     .serial_no = 1,
  68     .manuf_week = 1,
  69     .manuf_year = 2011,
  70     .h_cm = 40,
  71     .v_cm = 30,
  72     .gamma = 0x78,
  73     .monitor_name = "QEMU monitor",
  74     .serial_no_string = "1",
  75     .vmin = 40,
  76     .vmax = 120,
  77     .hmin = 30,
  78     .hmax = 100,
  79     .pixclock = 18,
  80     .timing_data = {
  81         /* Borrowed from a 21" LCD */
  82         0x48, 0x3f, 0x40, 0x30, 0x62, 0xb0, 0x32, 0x40, 0x40,
  83         0xc0, 0x13, 0x00, 0x98, 0x32, 0x11, 0x00, 0x00, 0x1e
  84     }
  85 };
  86
  87 static uint8_t manuf_char_to_int(char c)
  88 {
  89     return (c - 'A') & 0x1f;
  90 }
  91
  92 static void write_ascii_descriptor_block(uint8_t *descblob, uint8_t blocktype,
  93                                          const char *string)
  94 {
  95     /* Write an EDID Descriptor Block of the "ascii string" type */
  96     int i;
  97     descblob[0] = descblob[1] = descblob[2] = descblob[4] = 0;
  98     descblob[3] = blocktype;
  99     /* The rest is 13 bytes of ASCII; if less then the rest must
 100      * be filled with newline then spaces
 101      */
 102     for (i = 5; i < 19; i++) {
 103         descblob[i] = string[i - 5];
 104         if (!descblob[i]) {
 105             break;
 106         }
 107     }
 108     if (i < 19) {
 109         descblob[i++] = '\n';
 110     }
 111     for ( ; i < 19; i++) {
 112         descblob[i] = ' ';
 113     }
 114 }
 115
 116 static void write_range_limits_descriptor(const EDIDData *edid,
 117                                           uint8_t *descblob)
 118 {
 119     int i;
 120     descblob[0] = descblob[1] = descblob[2] = descblob[4] = 0;
 121     descblob[3] = 0xfd;
 122     descblob[5] = edid->vmin;
 123     descblob[6] = edid->vmax;
 124     descblob[7] = edid->hmin;
 125     descblob[8] = edid->hmax;
 126     descblob[9] = edid->pixclock;
 127     descblob[10] = 0;
 128     descblob[11] = 0xa;
 129     for (i = 12; i < 19; i++) {
 130         descblob[i] = 0x20;
 131     }
 132 }
 133
 134 static void build_edid_blob(const EDIDData *edid, uint8_t *blob)
 135 {
 136     /* Write an EDID 1.3 format blob (128 bytes) based
 137      * on the EDIDData structure.
 138      */
 139     int i;
 140     uint8_t cksum;
 141
 142     /* 00-07 : header */
 143     blob[0] = blob[7] = 0;
 144     for (i = 1 ; i < 7; i++) {
 145         blob[i] = 0xff;
 146     }
 147     /* 08-09 : manufacturer ID */
 148     blob[8] = (manuf_char_to_int(edid->manuf_id[0]) << 2)
 149         | (manuf_char_to_int(edid->manuf_id[1]) >> 3);
 150     blob[9] = (manuf_char_to_int(edid->manuf_id[1]) << 5)
 151         | manuf_char_to_int(edid->manuf_id[2]);
 152     /* 10-11 : product ID code */
 153     blob[10] = edid->product_id;
 154     blob[11] = edid->product_id >> 8;
 155     blob[12] = edid->serial_no;
 156     blob[13] = edid->serial_no >> 8;
 157     blob[14] = edid->serial_no >> 16;
 158     blob[15] = edid->serial_no >> 24;
 159     /* 16 : week of manufacture */
 160     blob[16] = edid->manuf_week;
 161     /* 17 : year of manufacture - 1990 */
 162     blob[17] = edid->manuf_year - 1990;
 163     /* 18, 19 : EDID version and revision */
 164     blob[18] = 1;
 165     blob[19] = 3;
 166     /* 20 - 24 : basic display parameters */
 167     /* We are always a digital display */
 168     blob[20] = 0x80;
 169     /* 21, 22 : max h/v size in cm */
 170     blob[21] = edid->h_cm;
 171     blob[22] = edid->v_cm;
 172     /* 23 : gamma (divide by 100 then add 1 for actual value) */
 173     blob[23] = edid->gamma;
 174     /* 24 feature support: no power management, RGB, preferred timing mode,
 175      * standard colour space
 176      */
 177     blob[24] = 0x0e;
 178     /* 25 - 34 : chromaticity coordinates. These are the
 179      * standard sRGB chromaticity values
 180      */
 181     blob[25] = 0xee;
 182     blob[26] = 0x91;
 183     blob[27] = 0xa3;
 184     blob[28] = 0x54;
 185     blob[29] = 0x4c;
 186     blob[30] = 0x99;
 187     blob[31] = 0x26;
 188     blob[32] = 0x0f;
 189     blob[33] = 0x50;
 190     blob[34] = 0x54;
 191     /* 35, 36 : Established timings: claim to support everything */
 192     blob[35] = blob[36] = 0xff;
 193     /* 37 : manufacturer's reserved timing: none */
 194     blob[37] = 0;
 195     /* 38 - 53 : standard timing identification
 196      * don't claim anything beyond what the 'established timings'
 197      * already provide. Unused slots must be (0x1, 0x1)
 198      */
 199     for (i = 38; i < 54; i++) {
 200         blob[i] = 0x1;
 201     }
 202     /* 54 - 71 : descriptor block 1 : must be preferred timing data */
 203     memcpy(blob + 54, edid->timing_data, 18);
 204     /* 72 - 89, 90 - 107, 108 - 125 : descriptor block 2, 3, 4
 205      * Order not important, but we must have a monitor name and a
 206      * range limits descriptor.
 207      */
 208     write_range_limits_descriptor(edid, blob + 72);
 209     write_ascii_descriptor_block(blob + 90, 0xfc, edid->monitor_name);
 210     write_ascii_descriptor_block(blob + 108, 0xff, edid->serial_no_string);
 211
 212     /* 126 : extension flag */
 213     blob[126] = 0;
 214
 215     cksum = 0;
 216     for (i = 0; i < 127; i++) {
 217         cksum += blob[i];
 218     }
 219     /* 127 : checksum */
 220     blob[127] = -cksum;
 221     if (DEBUG_I2CDDC) {
 222         qemu_hexdump((char *)blob, stdout, "", 128);
 223     }
 224 }
 225
 226 static void i2c_ddc_reset(DeviceState *ds)
 227 {
 228     I2CDDCState *s = I2CDDC(ds);
 229
 230     s->firstbyte = false;
 231     s->reg = 0;
 232 }
 233
 234 static int i2c_ddc_event(I2CSlave *i2c, enum i2c_event event)
 235 {
 236     I2CDDCState *s = I2CDDC(i2c);
 237
 238     if (event == I2C_START_SEND) {
 239         s->firstbyte = true;
 240     }
 241
 242     return 0;
 243 }
 244
 245 static int i2c_ddc_rx(I2CSlave *i2c)
 246 {
 247     I2CDDCState *s = I2CDDC(i2c);
 248
 249     int value;
 250     value = s->edid_blob[s->reg];
 251     s->reg++;
 252     return value;
 253 }
 254
 255 static int i2c_ddc_tx(I2CSlave *i2c, uint8_t data)
 256 {
 257     I2CDDCState *s = I2CDDC(i2c);
 258     if (s->firstbyte) {
 259         s->reg = data;
 260         s->firstbyte = false;
 261         DPRINTF("[EDID] Written new pointer: %u\n", data);
 262         return 0;
 263     }
 264
 265     /* Ignore all writes */
 266     s->reg++;
 267     return 0;
 268 }
 269
 270 static void i2c_ddc_init(Object *obj)
 271 {
 272     I2CDDCState *s = I2CDDC(obj);
 273     build_edid_blob(&lcd_edid, s->edid_blob);
 274 }
 275
 276 static const VMStateDescription vmstate_i2c_ddc = {
 277     .name = TYPE_I2CDDC,
 278     .version_id = 1,
 279     .fields = (VMStateField[]) {
 280         VMSTATE_BOOL(firstbyte, I2CDDCState),
 281         VMSTATE_UINT8(reg, I2CDDCState),
 282         VMSTATE_END_OF_LIST()
 283     }
 284 };
 285
 286 static void i2c_ddc_class_init(ObjectClass *oc, void *data)
 287 {
 288     DeviceClass *dc = DEVICE_CLASS(oc);
 289     I2CSlaveClass *isc = I2C_SLAVE_CLASS(oc);
 290
 291     dc->reset = i2c_ddc_reset;
 292     dc->vmsd = &vmstate_i2c_ddc;
 293     isc->event = i2c_ddc_event;
 294     isc->recv = i2c_ddc_rx;
 295     isc->send = i2c_ddc_tx;
 296 }
 297
 298 static TypeInfo i2c_ddc_info = {
 299     .name = TYPE_I2CDDC,
 300     .parent = TYPE_I2C_SLAVE,
 301     .instance_size = sizeof(I2CDDCState),
 302     .instance_init = i2c_ddc_init,
 303     .class_init = i2c_ddc_class_init
 304 };
 305
 306 static void ddc_register_devices(void)
 307 {
 308     type_register_static(&i2c_ddc_info);
 309 }
 310
 311 type_init(ddc_register_devices);