reactos/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 Library General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 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  * Library General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Library General Public
  17  * License along with this library; see the file COPYING.LIB.
  18  * If not, write to the Free Software Foundation,
  19  * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  20  *
  21  */
  22
  23 #include "videoprt.h"
  24
  25 #define DDC_EEPROM_ADDRESS  0xA0
  26
  27 /* PRIVATE FUNCTIONS **********************************************************/
  28
  29 #define LOW               0
  30 #define HIGH              1
  31 #define WRITE             0
  32 #define READ              1
  33 #define READ_SDA()        (i2c->ReadDataLine(HwDeviceExtension))
  34 #define READ_SCL()        (i2c->ReadClockLine(HwDeviceExtension))
  35 #define WRITE_SDA(state)  (i2c->WriteDataLine(HwDeviceExtension, state))
  36 #define WRITE_SCL(state)  (i2c->WriteClockLine(HwDeviceExtension, state))
  37
  38 STATIC LARGE_INTEGER HalfPeriodDelay = { { 70LL } };
  39 #define DELAY_HALF()      KeDelayExecutionThread(KernelMode, FALSE, &HalfPeriodDelay)
  40
  41
  42 STATIC BOOL
  43 I2CWrite(PVOID HwDeviceExtension, PI2C_CALLBACKS i2c, UCHAR Data)
  44 {
  45    UCHAR Bit;
  46    BOOL Ack;
  47
  48    /* transmit data */
  49    for (Bit = (1 << 7); Bit != 0; Bit >>= 1)
  50      {
  51         WRITE_SCL(LOW);
  52         WRITE_SDA((Data & Bit) ? HIGH : LOW);
  53         DELAY_HALF();
  54         WRITE_SCL(HIGH);
  55         DELAY_HALF();
  56      }
  57
  58    /* get ack */
  59    WRITE_SCL(LOW);
  60    WRITE_SDA(HIGH);
  61    DELAY_HALF();
  62    WRITE_SCL(HIGH);
  63    do
  64      {
  65         DELAY_HALF();
  66      }
  67    while (READ_SCL() != HIGH);
  68    Ack = (READ_SDA() == LOW);
  69    DELAY_HALF();
  70
  71    INFO_(VIDEOPRT, "I2CWrite: %s\n", Ack ? "Ack" : "Nak");
  72    return Ack;
  73 }
  74
  75
  76 STATIC UCHAR
  77 I2CRead(PVOID HwDeviceExtension, PI2C_CALLBACKS i2c, BOOL Ack)
  78 {
  79    INT Bit = 0x80;
  80    UCHAR Data = 0;
  81
  82    /* pull down SCL and release SDA */
  83    WRITE_SCL(LOW);
  84    WRITE_SDA(HIGH);
  85
  86    /* read byte */
  87    for (Bit = (1 << 7); Bit != 0; Bit >>= 1)
  88      {
  89         WRITE_SCL(LOW);
  90         DELAY_HALF();
  91         WRITE_SCL(HIGH);
  92         DELAY_HALF();
  93         if (READ_SDA() == HIGH)
  94           Data |= Bit;
  95      }
  96
  97    /* send ack/nak */
  98    WRITE_SCL(LOW);
  99    WRITE_SDA(Ack ? LOW : HIGH);
 100    DELAY_HALF();
 101    WRITE_SCL(HIGH);
 102    do
 103      {
 104         DELAY_HALF();
 105      }
 106    while (READ_SCL() != HIGH);
 107
 108    return Data;
 109 }
 110
 111
 112 STATIC VOID
 113 I2CStop(PVOID HwDeviceExtension, PI2C_CALLBACKS i2c)
 114 {
 115    WRITE_SCL(LOW);
 116    WRITE_SDA(LOW);
 117    DELAY_HALF();
 118    WRITE_SCL(HIGH);
 119    DELAY_HALF();
 120    WRITE_SDA(HIGH);
 121 }
 122
 123
 124 STATIC BOOL
 125 I2CStart(PVOID HwDeviceExtension, PI2C_CALLBACKS i2c, UCHAR Address)
 126 {
 127    /* make sure the bus is free */
 128    if (READ_SDA() == LOW || READ_SCL() == LOW)
 129      {
 130         WARN_(VIDEOPRT, "I2CStart: Bus is not free!\n");
 131         return FALSE;
 132      }
 133
 134    /* send address */
 135    WRITE_SDA(LOW);
 136    DELAY_HALF();
 137    if (!I2CWrite(HwDeviceExtension, i2c, Address))
 138      {
 139         /* ??release the bus?? */
 140         I2CStop(HwDeviceExtension, i2c);
 141         WARN_(VIDEOPRT, "I2CStart: Device not found (Address = 0x%x)\n", Address);
 142         return FALSE;
 143      }
 144
 145    INFO_(VIDEOPRT, "I2CStart: SUCCESS!\n");
 146    return TRUE;
 147 }
 148
 149
 150 STATIC BOOL
 151 I2CRepStart(PVOID HwDeviceExtension, PI2C_CALLBACKS i2c, UCHAR Address)
 152 {
 153    /* setup lines for repeated start condition */
 154    WRITE_SCL(LOW);
 155    DELAY_HALF();
 156    WRITE_SDA(HIGH);
 157    DELAY_HALF();
 158    WRITE_SCL(HIGH);
 159    DELAY_HALF();
 160
 161    return I2CStart(HwDeviceExtension, i2c, Address);
 162 }
 163
 164 /* PUBLIC FUNCTIONS ***********************************************************/
 165
 166 /*
 167  * @implemented
 168  */
 169
 170 BOOLEAN NTAPI
 171 VideoPortDDCMonitorHelper(
 172    PVOID HwDeviceExtension,
 173    PVOID I2CFunctions,
 174    PUCHAR pEdidBuffer,
 175    ULONG EdidBufferSize
 176    )
 177 {
 178    PDDC_CONTROL ddc = (PDDC_CONTROL)I2CFunctions;
 179    PI2C_CALLBACKS i2c = &ddc->I2CCallbacks;
 180    INT Count, i;
 181    PUCHAR pBuffer = (PUCHAR)pEdidBuffer;
 182    BOOL Ack;
 183
 184    TRACE_(VIDEOPRT, "VideoPortDDCMonitorHelper()\n");
 185
 186    ASSERT_IRQL_LESS_OR_EQUAL(PASSIVE_LEVEL);
 187    if (ddc->Size != sizeof (ddc))
 188      {
 189         WARN_(VIDEOPRT, "ddc->Size != %d (%d)\n", sizeof (ddc), ddc->Size);
 190         return FALSE;
 191      }
 192
 193    /* select eeprom */
 194    if (!I2CStart(HwDeviceExtension, i2c, DDC_EEPROM_ADDRESS | WRITE))
 195      return FALSE;
 196    /* set address */
 197    if (!I2CWrite(HwDeviceExtension, i2c, 0x00))
 198      return FALSE;
 199    /* change into read mode */
 200    if (!I2CRepStart(HwDeviceExtension, i2c, DDC_EEPROM_ADDRESS | READ))
 201      return FALSE;
 202    /* read eeprom */
 203    RtlZeroMemory(pEdidBuffer, EdidBufferSize);
 204    Count = min(128, EdidBufferSize);
 205    for (i = 0; i < Count; i++)
 206      {
 207         Ack = ((i + 1) < Count);
 208         pBuffer[i] = I2CRead(HwDeviceExtension, i2c, Ack);
 209      }
 210    I2CStop(HwDeviceExtension, i2c);
 211
 212    /* check EDID header */
 213    if (pBuffer[0] != 0x00 || pBuffer[1] != 0xff ||
 214        pBuffer[2] != 0xff || pBuffer[3] != 0xff ||
 215        pBuffer[4] != 0xff || pBuffer[5] != 0xff ||
 216        pBuffer[6] != 0xff || pBuffer[7] != 0x00)
 217      {
 218         WARN_(VIDEOPRT, "VideoPortDDCMonitorHelper(): Invalid EDID header!\n");
 219         return FALSE;
 220      }
 221
 222    INFO_(VIDEOPRT, "VideoPortDDCMonitorHelper(): EDID version %d rev. %d\n", pBuffer[18], pBuffer[19]);
 223    INFO_(VIDEOPRT, "VideoPortDDCMonitorHelper() - SUCCESS!\n");
 224    return TRUE;
 225 }
 226