ReactOS Development > Doxygen
Definition at line 14 of file legacy.c. Referenced by SerialPnpStartDevice(). {
UCHAR Lcr, TestLcr;
UCHAR OldScr, Scr5A, ScrA5;
BOOLEAN FifoEnabled;
UCHAR NewFifoStatus;
Lcr = READ_PORT_UCHAR(SER_LCR(BaseAddress));
WRITE_PORT_UCHAR(SER_LCR(BaseAddress), Lcr ^ 0xFF);
TestLcr = READ_PORT_UCHAR(SER_LCR(BaseAddress)) ^ 0xFF;
WRITE_PORT_UCHAR(SER_LCR(BaseAddress), Lcr);
/* Accessing the LCR must work for a usable serial port */
if (TestLcr != Lcr)
return UartUnknown;
/* Ensure that all following accesses are done as required */
READ_PORT_UCHAR(SER_RBR(BaseAddress));
READ_PORT_UCHAR(SER_IER(BaseAddress));
READ_PORT_UCHAR(SER_IIR(BaseAddress));
READ_PORT_UCHAR(SER_LCR(BaseAddress));
READ_PORT_UCHAR(SER_MCR(BaseAddress));
READ_PORT_UCHAR(SER_LSR(BaseAddress));
READ_PORT_UCHAR(SER_MSR(BaseAddress));
READ_PORT_UCHAR(SER_SCR(BaseAddress));
/* Test scratch pad */
OldScr = READ_PORT_UCHAR(SER_SCR(BaseAddress));
WRITE_PORT_UCHAR(SER_SCR(BaseAddress), 0x5A);
Scr5A = READ_PORT_UCHAR(SER_SCR(BaseAddress));
WRITE_PORT_UCHAR(SER_SCR(BaseAddress), 0xA5);
ScrA5 = READ_PORT_UCHAR(SER_SCR(BaseAddress));
WRITE_PORT_UCHAR(SER_SCR(BaseAddress), OldScr);
/* When non-functional, we have a 8250 */
if (Scr5A != 0x5A || ScrA5 != 0xA5)
return Uart8250;
/* Test FIFO type */
FifoEnabled = (READ_PORT_UCHAR(SER_IIR(BaseAddress)) & 0x80) != 0;
WRITE_PORT_UCHAR(SER_FCR(BaseAddress), SR_FCR_ENABLE_FIFO);
NewFifoStatus = READ_PORT_UCHAR(SER_IIR(BaseAddress)) & 0xC0;
if (!FifoEnabled)
WRITE_PORT_UCHAR(SER_FCR(BaseAddress), 0);
switch (NewFifoStatus)
{
case 0x00:
return Uart16450;
case 0x40:
case 0x80:
/* Not sure about this but the documentation says that 0x40
* indicates an unusable FIFO but my tests only worked
* with 0x80 */
return Uart16550;
}
/* FIFO is only functional for 16550A+ */
return Uart16550A;
}
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Generated on Sat May 26 2012 05:19:16 for ReactOS by
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