ddc.c File Reference

#include "videoprt.h"
#include <debug.h>

Include dependency graph for ddc.c:

Go to the source code of this file.

Macros
#define	NDEBUG
#define	DDC_EEPROM_ADDRESS   0xA0
#define	LOW   0
#define	HIGH   1
#define	WRITE   0
#define	READ   1
#define	READ_SDA()   (i2c->ReadDataLine(HwDeviceExtension))
#define	READ_SCL()   (i2c->ReadClockLine(HwDeviceExtension))
#define	WRITE_SDA(state)   (i2c->WriteDataLine(HwDeviceExtension, state))
#define	WRITE_SCL(state)   (i2c->WriteClockLine(HwDeviceExtension, state))
#define	DELAY_HALF()   KeDelayExecutionThread(KernelMode, FALSE, &HalfPeriodDelay)

Functions
static BOOL	I2CWrite (PVOID HwDeviceExtension, PI2C_CALLBACKS i2c, UCHAR Data)
static UCHAR	I2CRead (PVOID HwDeviceExtension, PI2C_CALLBACKS i2c, BOOL Ack)
static VOID	I2CStop (PVOID HwDeviceExtension, PI2C_CALLBACKS i2c)
static BOOL	I2CStart (PVOID HwDeviceExtension, PI2C_CALLBACKS i2c, UCHAR Address)
static BOOL	I2CRepStart (PVOID HwDeviceExtension, PI2C_CALLBACKS i2c, UCHAR Address)
BOOLEAN NTAPI	VideoPortDDCMonitorHelper (PVOID HwDeviceExtension, PVOID I2CFunctions, PUCHAR pEdidBuffer, ULONG EdidBufferSize)

Variables
static LARGE_INTEGER	HalfPeriodDelay = {{0, 70}}

Macro Definition Documentation

DDC_EEPROM_ADDRESS

#define DDC_EEPROM_ADDRESS   0xA0

Definition at line 27 of file ddc.c.

DELAY_HALF

#define DELAY_HALF

(

)

KeDelayExecutionThread(KernelMode, FALSE, &HalfPeriodDelay)

Definition at line 41 of file ddc.c.

HIGH

#define HIGH   1

Definition at line 32 of file ddc.c.

LOW

#define LOW   0

Definition at line 31 of file ddc.c.

NDEBUG

#define NDEBUG

Definition at line 24 of file ddc.c.

READ

#define READ   1

Definition at line 34 of file ddc.c.

READ_SCL

#define READ_SCL

(

)

(i2c->ReadClockLine(HwDeviceExtension))

Definition at line 36 of file ddc.c.

READ_SDA

#define READ_SDA

(

)

(i2c->ReadDataLine(HwDeviceExtension))

Definition at line 35 of file ddc.c.

WRITE

#define WRITE   0

Definition at line 33 of file ddc.c.

WRITE_SCL

#define WRITE_SCL

(

state

)

(i2c->WriteClockLine(HwDeviceExtension, state))

Definition at line 38 of file ddc.c.

WRITE_SDA

#define WRITE_SDA

(

state

)

(i2c->WriteDataLine(HwDeviceExtension, state))

Definition at line 37 of file ddc.c.

Function Documentation

I2CRead()

static UCHAR I2CRead ( PVOID  HwDeviceExtension, PI2C_CALLBACKS  i2c, BOOL  Ack  )

static

Definition at line 79 of file ddc.c.

{
   INT Bit = 0x80;
   UCHAR Data = 0;
 
   /* pull down SCL and release SDA */
   WRITE_SCL(LOW);
   WRITE_SDA(HIGH);
 
   /* read byte */
   for (Bit = (1 << 7); Bit != 0; Bit >>= 1)
     {
        WRITE_SCL(LOW);
        DELAY_HALF();
        WRITE_SCL(HIGH);
        DELAY_HALF();
        if (READ_SDA() == HIGH)
          Data |= Bit;
     }
 
   /* send ack/nak */
   WRITE_SCL(LOW);
   WRITE_SDA(Ack ? LOW : HIGH);
   DELAY_HALF();
   WRITE_SCL(HIGH);
   do
     {
        DELAY_HALF();
     }
   while (READ_SCL() != HIGH);
 
   return Data;
}

Referenced by VideoPortDDCMonitorHelper().

I2CRepStart()

static BOOL I2CRepStart ( PVOID  HwDeviceExtension, PI2C_CALLBACKS  i2c, UCHAR  Address  )

static

Definition at line 153 of file ddc.c.

{
   /* setup lines for repeated start condition */
   WRITE_SCL(LOW);
   DELAY_HALF();
   WRITE_SDA(HIGH);
   DELAY_HALF();
   WRITE_SCL(HIGH);
   DELAY_HALF();
 
   return I2CStart(HwDeviceExtension, i2c, Address);
}

Referenced by VideoPortDDCMonitorHelper().

I2CStart()

static BOOL I2CStart ( PVOID  HwDeviceExtension, PI2C_CALLBACKS  i2c, UCHAR  Address  )

static

Definition at line 127 of file ddc.c.

{
   /* make sure the bus is free */
   if (READ_SDA() == LOW || READ_SCL() == LOW)
     {
        WARN_(VIDEOPRT, "I2CStart: Bus is not free!\n");
        return FALSE;
     }
 
   /* send address */
   WRITE_SDA(LOW);
   DELAY_HALF();
   if (!I2CWrite(HwDeviceExtension, i2c, Address))
     {
        /* ??release the bus?? */
        I2CStop(HwDeviceExtension, i2c);
        WARN_(VIDEOPRT, "I2CStart: Device not found (Address = 0x%x)\n", Address);
        return FALSE;
     }
 
   INFO_(VIDEOPRT, "I2CStart: SUCCESS!\n");
   return TRUE;
}

Referenced by I2CRepStart(), and VideoPortDDCMonitorHelper().

I2CStop()

static VOID I2CStop ( PVOID  HwDeviceExtension, PI2C_CALLBACKS  i2c  )

static

Definition at line 115 of file ddc.c.

{
   WRITE_SCL(LOW);
   WRITE_SDA(LOW);
   DELAY_HALF();
   WRITE_SCL(HIGH);
   DELAY_HALF();
   WRITE_SDA(HIGH);
}

Referenced by I2CStart(), and VideoPortDDCMonitorHelper().

I2CWrite()

static BOOL I2CWrite ( PVOID  HwDeviceExtension, PI2C_CALLBACKS  i2c, UCHAR  Data  )

static

Definition at line 45 of file ddc.c.

{
   UCHAR Bit;
   BOOL Ack;
 
   /* transmit data */
   for (Bit = (1 << 7); Bit != 0; Bit >>= 1)
     {
        WRITE_SCL(LOW);
        WRITE_SDA((Data & Bit) ? HIGH : LOW);
        DELAY_HALF();
        WRITE_SCL(HIGH);
        DELAY_HALF();
     }
 
   /* get ack */
   WRITE_SCL(LOW);
   WRITE_SDA(HIGH);
   DELAY_HALF();
   WRITE_SCL(HIGH);
   do
     {
        DELAY_HALF();
     }
   while (READ_SCL() != HIGH);
   Ack = (READ_SDA() == LOW);
   DELAY_HALF();
 
   INFO_(VIDEOPRT, "I2CWrite: %s\n", Ack ? "Ack" : "Nak");
   return Ack;
}

Referenced by I2CStart(), and VideoPortDDCMonitorHelper().

VideoPortDDCMonitorHelper()

BOOLEAN NTAPI VideoPortDDCMonitorHelper	(	PVOID	HwDeviceExtension,
		PVOID	I2CFunctions,
		PUCHAR	pEdidBuffer,
		ULONG	EdidBufferSize
	)

Definition at line 173 of file ddc.c.

{
   PDDC_CONTROL ddc = (PDDC_CONTROL)I2CFunctions;
   PI2C_CALLBACKS i2c = &ddc->I2CCallbacks;
   INT Count, i;
   PUCHAR pBuffer = (PUCHAR)pEdidBuffer;
   BOOL Ack;
 
   TRACE_(VIDEOPRT, "VideoPortDDCMonitorHelper()\n");
 
   ASSERT_IRQL_LESS_OR_EQUAL(PASSIVE_LEVEL);
   if (ddc->Size != sizeof (ddc))
     {
        WARN_(VIDEOPRT, "ddc->Size != %d (%d)\n", sizeof (ddc), ddc->Size);
        return FALSE;
     }
 
   /* select eeprom */
   if (!I2CStart(HwDeviceExtension, i2c, DDC_EEPROM_ADDRESS | WRITE))
     return FALSE;
   /* set address */
   if (!I2CWrite(HwDeviceExtension, i2c, 0x00))
     return FALSE;
   /* change into read mode */
   if (!I2CRepStart(HwDeviceExtension, i2c, DDC_EEPROM_ADDRESS | READ))
     return FALSE;
   /* read eeprom */
   RtlZeroMemory(pEdidBuffer, EdidBufferSize);
   Count = min(128, EdidBufferSize);
   for (i = 0; i < Count; i++)
     {
        Ack = ((i + 1) < Count);
        pBuffer[i] = I2CRead(HwDeviceExtension, i2c, Ack);
     }
   I2CStop(HwDeviceExtension, i2c);
 
   /* check EDID header */
   if (pBuffer[0] != 0x00 || pBuffer[1] != 0xff ||
       pBuffer[2] != 0xff || pBuffer[3] != 0xff ||
       pBuffer[4] != 0xff || pBuffer[5] != 0xff ||
       pBuffer[6] != 0xff || pBuffer[7] != 0x00)
     {
        WARN_(VIDEOPRT, "VideoPortDDCMonitorHelper(): Invalid EDID header!\n");
        return FALSE;
     }
 
   INFO_(VIDEOPRT, "VideoPortDDCMonitorHelper(): EDID version %d rev. %d\n", pBuffer[18], pBuffer[19]);
   INFO_(VIDEOPRT, "VideoPortDDCMonitorHelper() - SUCCESS!\n");
   return TRUE;
}

Variable Documentation

HalfPeriodDelay

LARGE_INTEGER HalfPeriodDelay = {{0, 70}}

static

Definition at line 40 of file ddc.c.