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