drivers/video/videoprt/ddc.c

   1 /*
   2  * VideoPort driver
   3  *
   4  * Copyright (C) 2002, 2003, 2004 ReactOS Team
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  19  *
  20  */
  21
  22 #include "videoprt.h"
  23
  24 #define DDC_EEPROM_ADDRESS  0xA0
  25
  26 /* PRIVATE FUNCTIONS **********************************************************/
  27
  28 #define LOW               0
  29 #define HIGH              1
  30 #define WRITE             0
  31 #define READ              1
  32 #define READ_SDA()        (i2c->ReadDataLine(HwDeviceExtension))
  33 #define READ_SCL()        (i2c->ReadClockLine(HwDeviceExtension))
  34 #define WRITE_SDA(state)  (i2c->WriteDataLine(HwDeviceExtension, state))
  35 #define WRITE_SCL(state)  (i2c->WriteClockLine(HwDeviceExtension, state))
  36
  37 static LARGE_INTEGER HalfPeriodDelay = {{0, 70}};
  38 #define DELAY_HALF()      KeDelayExecutionThread(KernelMode, FALSE, &HalfPeriodDelay)
  39
  40
  41 static BOOL
  42 I2CWrite(PVOID HwDeviceExtension, PI2C_CALLBACKS i2c, UCHAR Data)
  43 {
  44    UCHAR Bit;
  45    BOOL Ack;
  46
  47    /* transmit data */
  48    for (Bit = (1 << 7); Bit != 0; Bit >>= 1)
  49      {
  50         WRITE_SCL(LOW);
  51         WRITE_SDA((Data & Bit) ? HIGH : LOW);
  52         DELAY_HALF();
  53         WRITE_SCL(HIGH);
  54         DELAY_HALF();
  55      }
  56
  57    /* get ack */
  58    WRITE_SCL(LOW);
  59    WRITE_SDA(HIGH);
  60    DELAY_HALF();
  61    WRITE_SCL(HIGH);
  62    do
  63      {
  64         DELAY_HALF();
  65      }
  66    while (READ_SCL() != HIGH);
  67    Ack = (READ_SDA() == LOW);
  68    DELAY_HALF();
  69
  70    INFO_(VIDEOPRT, "I2CWrite: %s\n", Ack ? "Ack" : "Nak");
  71    return Ack;
  72 }
  73
  74
  75 static UCHAR
  76 I2CRead(PVOID HwDeviceExtension, PI2C_CALLBACKS i2c, BOOL Ack)
  77 {
  78    INT Bit = 0x80;
  79    UCHAR Data = 0;
  80
  81    /* pull down SCL and release SDA */
  82    WRITE_SCL(LOW);
  83    WRITE_SDA(HIGH);
  84
  85    /* read byte */
  86    for (Bit = (1 << 7); Bit != 0; Bit >>= 1)
  87      {
  88         WRITE_SCL(LOW);
  89         DELAY_HALF();
  90         WRITE_SCL(HIGH);
  91         DELAY_HALF();
  92         if (READ_SDA() == HIGH)
  93           Data |= Bit;
  94      }
  95
  96    /* send ack/nak */
  97    WRITE_SCL(LOW);
  98    WRITE_SDA(Ack ? LOW : HIGH);
  99    DELAY_HALF();
 100    WRITE_SCL(HIGH);
 101    do
 102      {
 103         DELAY_HALF();
 104      }
 105    while (READ_SCL() != HIGH);
 106
 107    return Data;
 108 }
 109
 110
 111 static VOID
 112 I2CStop(PVOID HwDeviceExtension, PI2C_CALLBACKS i2c)
 113 {
 114    WRITE_SCL(LOW);
 115    WRITE_SDA(LOW);
 116    DELAY_HALF();
 117    WRITE_SCL(HIGH);
 118    DELAY_HALF();
 119    WRITE_SDA(HIGH);
 120 }
 121
 122
 123 static BOOL
 124 I2CStart(PVOID HwDeviceExtension, PI2C_CALLBACKS i2c, UCHAR Address)
 125 {
 126    /* make sure the bus is free */
 127    if (READ_SDA() == LOW || READ_SCL() == LOW)
 128      {
 129         WARN_(VIDEOPRT, "I2CStart: Bus is not free!\n");
 130         return FALSE;
 131      }
 132
 133    /* send address */
 134    WRITE_SDA(LOW);
 135    DELAY_HALF();
 136    if (!I2CWrite(HwDeviceExtension, i2c, Address))
 137      {
 138         /* ??release the bus?? */
 139         I2CStop(HwDeviceExtension, i2c);
 140         WARN_(VIDEOPRT, "I2CStart: Device not found (Address = 0x%x)\n", Address);
 141         return FALSE;
 142      }
 143
 144    INFO_(VIDEOPRT, "I2CStart: SUCCESS!\n");
 145    return TRUE;
 146 }
 147
 148
 149 static BOOL
 150 I2CRepStart(PVOID HwDeviceExtension, PI2C_CALLBACKS i2c, UCHAR Address)
 151 {
 152    /* setup lines for repeated start condition */
 153    WRITE_SCL(LOW);
 154    DELAY_HALF();
 155    WRITE_SDA(HIGH);
 156    DELAY_HALF();
 157    WRITE_SCL(HIGH);
 158    DELAY_HALF();
 159
 160    return I2CStart(HwDeviceExtension, i2c, Address);
 161 }
 162
 163 /* PUBLIC FUNCTIONS ***********************************************************/
 164
 165 /*
 166  * @implemented
 167  */
 168
 169 BOOLEAN NTAPI
 170 VideoPortDDCMonitorHelper(
 171    PVOID HwDeviceExtension,
 172    PVOID I2CFunctions,
 173    PUCHAR pEdidBuffer,
 174    ULONG EdidBufferSize
 175    )
 176 {
 177    PDDC_CONTROL ddc = (PDDC_CONTROL)I2CFunctions;
 178    PI2C_CALLBACKS i2c = &ddc->I2CCallbacks;
 179    INT Count, i;
 180    PUCHAR pBuffer = (PUCHAR)pEdidBuffer;
 181    BOOL Ack;
 182
 183    TRACE_(VIDEOPRT, "VideoPortDDCMonitorHelper()\n");
 184
 185    ASSERT_IRQL_LESS_OR_EQUAL(PASSIVE_LEVEL);
 186    if (ddc->Size != sizeof (ddc))
 187      {
 188         WARN_(VIDEOPRT, "ddc->Size != %d (%d)\n", sizeof (ddc), ddc->Size);
 189         return FALSE;
 190      }
 191
 192    /* select eeprom */
 193    if (!I2CStart(HwDeviceExtension, i2c, DDC_EEPROM_ADDRESS | WRITE))
 194      return FALSE;
 195    /* set address */
 196    if (!I2CWrite(HwDeviceExtension, i2c, 0x00))
 197      return FALSE;
 198    /* change into read mode */
 199    if (!I2CRepStart(HwDeviceExtension, i2c, DDC_EEPROM_ADDRESS | READ))
 200      return FALSE;
 201    /* read eeprom */
 202    RtlZeroMemory(pEdidBuffer, EdidBufferSize);
 203    Count = min(128, EdidBufferSize);
 204    for (i = 0; i < Count; i++)
 205      {
 206         Ack = ((i + 1) < Count);
 207         pBuffer[i] = I2CRead(HwDeviceExtension, i2c, Ack);
 208      }
 209    I2CStop(HwDeviceExtension, i2c);
 210
 211    /* check EDID header */
 212    if (pBuffer[0] != 0x00 || pBuffer[1] != 0xff ||
 213        pBuffer[2] != 0xff || pBuffer[3] != 0xff ||
 214        pBuffer[4] != 0xff || pBuffer[5] != 0xff ||
 215        pBuffer[6] != 0xff || pBuffer[7] != 0x00)
 216      {
 217         WARN_(VIDEOPRT, "VideoPortDDCMonitorHelper(): Invalid EDID header!\n");
 218         return FALSE;
 219      }
 220
 221    INFO_(VIDEOPRT, "VideoPortDDCMonitorHelper(): EDID version %d rev. %d\n", pBuffer[18], pBuffer[19]);
 222    INFO_(VIDEOPRT, "VideoPortDDCMonitorHelper() - SUCCESS!\n");
 223    return TRUE;
 224 }
 225