514 lines
12 KiB
C
514 lines
12 KiB
C
/*++
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Copyright (c) 1990-2000 Microsoft Corporation
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Module Name:
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i2c.c
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Abstract:
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This is the NT Video port I2C helper code.
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Author:
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Michael Maciesowicz (mmacie) 03-Sept-1999
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Environment:
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kernel mode only
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Notes:
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--*/
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#include "videoprt.h"
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//
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// Define constants used by I2C.
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//
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#define I2C_START_RETRIES 10
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#define I2C_SCL_READ_RETRIES 10
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#define I2C_DELAY() DELAY_MICROSECONDS(5)
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#ifdef ALLOC_PRAGMA
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#pragma alloc_text (PAGE, I2CStart)
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#pragma alloc_text (PAGE, I2CStop)
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#pragma alloc_text (PAGE, I2CWrite)
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#pragma alloc_text (PAGE, I2CRead)
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#pragma alloc_text (PAGE, I2CWriteByte)
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#pragma alloc_text (PAGE, I2CReadByte)
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#pragma alloc_text (PAGE, I2CWaitForClockLineHigh)
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#endif // ALLOC_PRAGMA
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//
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// Routines exported via VideoPortQueryServices().
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//
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BOOLEAN
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I2CStart(
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IN PVOID pHwDeviceExtension,
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IN PI2C_CALLBACKS pI2CCallbacks
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)
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/*++
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Routine Description:
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This routine starts I2C communication.
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Arguments:
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pHwDeviceExtension - Points to per-adapter device extension.
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pI2CCallbacks - I2C hardware specific functions.
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Returns:
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TRUE - Start OK.
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FALSE - Start failed.
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--*/
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{
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ULONG ulRetry;
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PAGED_CODE();
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ASSERT(NULL != pHwDeviceExtension);
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ASSERT(NULL != pI2CCallbacks);
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ASSERT(NULL != pI2CCallbacks->WriteClockLine);
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ASSERT(NULL != pI2CCallbacks->WriteDataLine);
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ASSERT(NULL != pI2CCallbacks->ReadClockLine);
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ASSERT(NULL != pI2CCallbacks->ReadDataLine);
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ASSERT(IS_HW_DEVICE_EXTENSION(pHwDeviceExtension) == TRUE);
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//
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// The I2C communications start signal is a SDA high->low while the SCL is high.
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//
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for (ulRetry = 0; ulRetry <= I2C_START_RETRIES; ulRetry++)
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{
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pI2CCallbacks->WriteDataLine(pHwDeviceExtension, 1); // Set SDA high
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I2C_DELAY();
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if (pI2CCallbacks->ReadDataLine(pHwDeviceExtension) == FALSE) // SDA didn't take - ulRetry
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continue;
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pI2CCallbacks->WriteClockLine(pHwDeviceExtension, 1); // Set SCL high
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I2C_DELAY();
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if (I2CWaitForClockLineHigh(pHwDeviceExtension, pI2CCallbacks) == FALSE)
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{
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pVideoDebugPrint((Warn, "VIDEOPRT: I2CStart: SCL didn't take\n"));
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break;
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}
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pI2CCallbacks->WriteDataLine(pHwDeviceExtension, 0); // Set SDA low
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I2C_DELAY();
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pI2CCallbacks->WriteClockLine(pHwDeviceExtension, 0); // Set SCL low
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I2C_DELAY();
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return TRUE;
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}
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pVideoDebugPrint((Warn, "VIDEOPRT: I2CStart: Failed\n"));
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return FALSE;
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} // I2CStart()
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BOOLEAN
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I2CStop(
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IN PVOID pHwDeviceExtension,
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IN PI2C_CALLBACKS pI2CCallbacks
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)
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/*++
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Routine Description:
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This routine stops I2C communication.
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Arguments:
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pHwDeviceExtension - Points to per-adapter device extension.
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pI2CCallbacks - I2C hardware specific functions.
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Returns:
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TRUE - Stop OK.
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FALSE - Stop failed.
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--*/
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{
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PAGED_CODE();
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ASSERT(NULL != pHwDeviceExtension);
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ASSERT(NULL != pI2CCallbacks);
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ASSERT(NULL != pI2CCallbacks->WriteClockLine);
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ASSERT(NULL != pI2CCallbacks->WriteDataLine);
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ASSERT(NULL != pI2CCallbacks->ReadClockLine);
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ASSERT(NULL != pI2CCallbacks->ReadDataLine);
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ASSERT(IS_HW_DEVICE_EXTENSION(pHwDeviceExtension) == TRUE);
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//
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// The I2C communications stop signal is a SDA low->high while the SCL is high.
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//
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pI2CCallbacks->WriteDataLine(pHwDeviceExtension, 0); // Set SDA low
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I2C_DELAY();
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pI2CCallbacks->WriteClockLine(pHwDeviceExtension, 1); // Set SCL high
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I2C_DELAY();
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if (I2CWaitForClockLineHigh(pHwDeviceExtension, pI2CCallbacks) == FALSE)
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{
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pVideoDebugPrint((Warn, "VIDEOPRT: I2CStop: SCL didn't take\n"));
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return FALSE;
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}
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pI2CCallbacks->WriteDataLine(pHwDeviceExtension, 1); // Set SDA high
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I2C_DELAY();
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if (pI2CCallbacks->ReadDataLine(pHwDeviceExtension) != 1)
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{
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pVideoDebugPrint((Warn, "VIDEOPRT: I2CStop: SDA didn't take\n"));
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return FALSE;
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}
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return TRUE;
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} // I2CStop()
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BOOLEAN
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I2CWrite(
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IN PVOID pHwDeviceExtension,
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IN PI2C_CALLBACKS pI2CCallbacks,
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IN PUCHAR pucBuffer,
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IN ULONG ulLength
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)
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/*++
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Routine Description:
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This routine writes data over the I2C channel.
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Arguments:
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pHwDeviceExtension - Points to per-adapter device extension.
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pI2CCallbacks - I2C hardware specific functions.
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pucBuffer - Points to data to be written.
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ulLength - Number of bytes to write.
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Returns:
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TRUE - Write OK.
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FALSE - Write failed.
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--*/
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{
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ULONG ulCount;
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PAGED_CODE();
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ASSERT(NULL != pHwDeviceExtension);
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ASSERT(NULL != pI2CCallbacks);
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ASSERT(NULL != pucBuffer);
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ASSERT(NULL != pI2CCallbacks->WriteClockLine);
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ASSERT(NULL != pI2CCallbacks->WriteDataLine);
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ASSERT(NULL != pI2CCallbacks->ReadClockLine);
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ASSERT(NULL != pI2CCallbacks->ReadDataLine);
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ASSERT(IS_HW_DEVICE_EXTENSION(pHwDeviceExtension) == TRUE);
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for (ulCount = 0; ulCount < ulLength; ulCount++)
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{
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if (I2CWriteByte(pHwDeviceExtension, pI2CCallbacks, pucBuffer[ulCount]) == FALSE)
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{
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return FALSE;
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}
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}
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return TRUE;
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} // I2CWrite()
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BOOLEAN
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I2CRead(
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IN PVOID pHwDeviceExtension,
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IN PI2C_CALLBACKS pI2CCallbacks,
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OUT PUCHAR pucBuffer,
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IN ULONG ulLength
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)
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/*++
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Routine Description:
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This routine reads data over the I2C channel.
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Arguments:
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pHwDeviceExtension - Points to per-adapter device extension.
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pI2CCallbacks - I2C hardware specific functions.
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pucBuffer - Points to storage for data.
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ulLength - Number of bytes to read.
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Returns:
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TRUE - Read OK.
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FALSE - Read failed.
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--*/
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{
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ULONG ulCount;
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PAGED_CODE();
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ASSERT(NULL != pHwDeviceExtension);
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ASSERT(NULL != pI2CCallbacks);
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ASSERT(NULL != pucBuffer);
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ASSERT(NULL != pI2CCallbacks->WriteClockLine);
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ASSERT(NULL != pI2CCallbacks->WriteDataLine);
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ASSERT(NULL != pI2CCallbacks->ReadClockLine);
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ASSERT(NULL != pI2CCallbacks->ReadDataLine);
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ASSERT(IS_HW_DEVICE_EXTENSION(pHwDeviceExtension) == TRUE);
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//
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// On all but the last byte, we must send an ACK in order to ensure that the sending device will
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// send subsequent data bytes. On the last byte, we must send a NAK so that it will shut up.
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//
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for (ulCount = 0; ulCount < ulLength; ulCount++)
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{
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if (ulLength - 1 == ulCount)
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{
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if (I2CReadByte(pHwDeviceExtension, pI2CCallbacks, pucBuffer + ulCount, FALSE) == FALSE) // Last byte
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{
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return FALSE;
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}
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}
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else
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{
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if (I2CReadByte(pHwDeviceExtension, pI2CCallbacks, pucBuffer + ulCount, TRUE) == FALSE)
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{
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return FALSE;
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}
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}
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}
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return TRUE;
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} // I2CRead()
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//
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// Local routines.
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//
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BOOLEAN
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I2CWriteByte(
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IN PVOID pHwDeviceExtension,
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IN PI2C_CALLBACKS pI2CCallbacks,
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IN UCHAR ucByte
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)
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/*++
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Routine Description:
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This routine writes byte over the I2C channel.
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Arguments:
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pHwDeviceExtension - Points to per-adapter device extension.
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pI2CCallbacks - I2C hardware specific functions.
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ucByte - Byte to write.
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Returns:
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TRUE - Write OK.
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FALSE - Write failed.
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--*/
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{
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LONG lShift;
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UCHAR ucAck;
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PAGED_CODE();
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ASSERT(NULL != pHwDeviceExtension);
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ASSERT(NULL != pI2CCallbacks);
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//
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// Bits are transmitted serially starting with the MSB.
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//
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for (lShift = 7; lShift >= 0; lShift--)
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{
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//
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// Transmitt data bit.
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//
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pI2CCallbacks->WriteDataLine(pHwDeviceExtension, (UCHAR)((ucByte >> lShift) & 0x01)); // Set SDA
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I2C_DELAY();
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//
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// After each data bit we must send high->low SCL pulse.
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//
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pI2CCallbacks->WriteClockLine(pHwDeviceExtension, 1); // Set SCL high
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I2C_DELAY();
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if (I2CWaitForClockLineHigh(pHwDeviceExtension, pI2CCallbacks) == FALSE)
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{
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pVideoDebugPrint((Warn, "VIDEOPRT: I2CWriteByte: SCL didn't take\n"));
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return FALSE;
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}
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pI2CCallbacks->WriteClockLine(pHwDeviceExtension, 0); // Set SCL low
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I2C_DELAY();
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}
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//
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// The monitor sends ACK by preventing the SDA from going high after the clock pulse we use
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// to send our last data bit. If the SDA goes high after this bit, it is a NAK from the monitor.
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//
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pI2CCallbacks->WriteDataLine(pHwDeviceExtension, 1); // Set SDA high
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I2C_DELAY();
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pI2CCallbacks->WriteClockLine(pHwDeviceExtension, 1); // Set SCL high
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I2C_DELAY();
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if (I2CWaitForClockLineHigh(pHwDeviceExtension, pI2CCallbacks) == FALSE)
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{
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pVideoDebugPrint((Warn, "VIDEOPRT: I2CWriteByte: SCL didn't take - ACK failed\n"));
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return FALSE;
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}
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ucAck = pI2CCallbacks->ReadDataLine(pHwDeviceExtension); // Read ACK bit
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pI2CCallbacks->WriteClockLine(pHwDeviceExtension, 0); // Set SCL low
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I2C_DELAY();
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if (1 == ucAck) // NAK from the monitor
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{
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pVideoDebugPrint((Warn, "VIDEOPRT: I2CWriteByte: NAK received\n"));
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return FALSE;
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}
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return TRUE;
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} // I2CWriteByte()
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BOOLEAN
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I2CReadByte(
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IN PVOID pHwDeviceExtension,
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IN PI2C_CALLBACKS pI2CCallbacks,
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OUT PUCHAR pucByte,
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IN BOOLEAN bMore
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)
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/*++
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Routine Description:
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This routine reads byte over the I2C channel.
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Arguments:
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pHwDeviceExtension - Points to per-adapter device extension.
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pI2CCallbacks - I2C hardware specific functions.
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pucBuffer - Points to storage for data.
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bMore - TRUE if we want to continue reading, FALSE otherwise.
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Returns:
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TRUE - Read OK.
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FALSE - Read failed.
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--*/
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{
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LONG lShift;
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PAGED_CODE();
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ASSERT(NULL != pHwDeviceExtension);
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ASSERT(NULL != pI2CCallbacks);
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ASSERT(NULL != pucByte);
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*pucByte = 0;
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//
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// The data bits are read from MSB to LSB. A data bit is read while the SCL is high.
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//
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for (lShift = 7; lShift >= 0; lShift--)
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{
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pI2CCallbacks->WriteClockLine(pHwDeviceExtension, 1); // Set SCL high
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I2C_DELAY();
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if (I2CWaitForClockLineHigh(pHwDeviceExtension, pI2CCallbacks) == FALSE)
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{
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pVideoDebugPrint((Warn, "VIDEOPRT: I2CReadByte: SCL didn't take\n"));
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return FALSE;
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}
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*pucByte |= pI2CCallbacks->ReadDataLine(pHwDeviceExtension) << lShift; // Read SDA
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pI2CCallbacks->WriteClockLine(pHwDeviceExtension, 0); // Set SCL low
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I2C_DELAY();
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}
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//
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// Send the acknowledge bit. SDA low = ACK, SDA high = NAK.
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//
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if (TRUE == bMore)
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{
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pI2CCallbacks->WriteDataLine(pHwDeviceExtension, 0); // Set SDA low - ACK
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}
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else
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{
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pI2CCallbacks->WriteDataLine(pHwDeviceExtension, 1); // Set SDA high - NAK
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}
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I2C_DELAY();
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//
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// Send a SCL high->low pulse, then release the SDA by setting it high.
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//
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pI2CCallbacks->WriteClockLine(pHwDeviceExtension, 1); // Set SCL high
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I2C_DELAY();
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if (I2CWaitForClockLineHigh(pHwDeviceExtension, pI2CCallbacks) == FALSE)
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{
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pVideoDebugPrint((Warn, "VIDEOPRT: I2CReadByte: SCL didn't take - ACK failed\n"));
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return FALSE;
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}
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pI2CCallbacks->WriteClockLine(pHwDeviceExtension, 0); // Set SCL low
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I2C_DELAY();
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pI2CCallbacks->WriteDataLine(pHwDeviceExtension, 1); // Set SDA high
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I2C_DELAY();
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return TRUE;
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} // I2CReadByte()
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BOOLEAN
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I2CWaitForClockLineHigh(
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IN PVOID pHwDeviceExtension,
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IN PI2C_CALLBACKS pI2CCallbacks
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)
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/*++
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Routine Description:
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This routine waits till SCL goes high
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(SCL low period can be stretched by slow devices).
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Arguments:
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pHwDeviceExtension - Points to per-adapter device extension.
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pI2CCallbacks - I2C hardware specific functions.
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Returns:
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TRUE - OK - SCL high.
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FALSE - SCL didn't take.
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--*/
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{
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ULONG ulCount;
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PAGED_CODE();
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ASSERT(NULL != pHwDeviceExtension);
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ASSERT(NULL != pI2CCallbacks);
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for (ulCount = 0; ulCount < I2C_SCL_READ_RETRIES; ulCount++)
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{
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if (pI2CCallbacks->ReadClockLine(pHwDeviceExtension) == TRUE)
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return TRUE;
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I2C_DELAY();
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}
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return FALSE;
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} // I2CWaitForClockLineHigh()
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