/* * PROJECT: ReactOS ComPort Library * LICENSE: BSD - See COPYING.ARM in the top level directory * FILE: lib/reactos/cportlib/cport.c * PURPOSE: Provides a serial port library for KDCOM, INIT, and FREELDR * PROGRAMMERS: ReactOS Portable Systems Group */ /* NOTE: This library follows the precise serial port intialization steps documented * by Microsoft in some of their Server hardware guidance. Because they've clearly * documented their serial algorithms, we use the same ones to stay "compliant". * Do not change this code to "improve" it. It's done this way on purpose, at least on x86. * -- sir_richard */ /* NOTE: This code is used by Headless Support (Ntoskrnl.exe and Osloader.exe) and Kdcom.dll in Windows. It may be that WinDBG depends on some of these quirks. */ /* NOTE: The original code supports Modem Control. We currently do not */ /* FIXMEs: - Make this serial-port specific (NS16550 vs other serial port types) - Get x64 KDCOM, KDBG, FREELDR, and other current code to use this */ /* INCLUDES *******************************************************************/ #include #include #include #include #include /* GLOBALS ********************************************************************/ UCHAR RingIndicator; /* FUNCTIONS ******************************************************************/ VOID NTAPI CpInitialize(IN PCPPORT Port, IN PUCHAR Address, IN ULONG Rate) { /* Reset port data */ Port->Address = Address; Port->Baud = 0; /* Set the baud rate */ CpSetBaud(Port, Rate); /* Enable on DTR and RTS */ WRITE_PORT_UCHAR(Address + MODEM_CONTROL_REGISTER, SERIAL_MCR_DTR | SERIAL_MCR_RTS); /* Disable interrupts */ WRITE_PORT_UCHAR(Address + INTERRUPT_ENABLE_REGISTER, 0); } VOID NTAPI CpEnableFifo(IN PUCHAR Address, IN BOOLEAN Enable) { /* Set FIFO */ WRITE_PORT_UCHAR(Address + FIFO_CONTROL_REGISTER, Enable ? SERIAL_FCR_ENABLE : 0); } BOOLEAN NTAPI CpDoesPortExist(IN PUCHAR Address) { UCHAR Old; /* * See "Building Hardware and Firmware to Complement Microsoft Windows Headless Operation" * Out-of-Band Management Port Device Requirements: * The device must act as a 16550 or 16450 UART. * Windows Server 2003 will test this device using the following process. * 1. Save off the current modem status register. * 2. Place the UART into diagnostic mode (The UART is placed into loopback mode * by writing SERIAL_MCR_LOOP to the modem control register). * 3. The modem status register is read and the high bits are checked. This means * SERIAL_MSR_CTS, SERIAL_MSR_DSR, SERIAL_MSR_RI and SERIAL_MSR_DCD should * all be clear. * 4. Place the UART in diagnostic mode and turn on OUTPUT (Loopback Mode and * OUTPUT are both turned on by writing (SERIAL_MCR_LOOP | SERIAL_MCR_OUT1) * to the modem control register). * 5. The modem status register is read and the ring indicator is checked. * This means SERIAL_MSR_RI should be set. * 6. Restore original modem status register. */ Old = READ_PORT_UCHAR(Address + MODEM_CONTROL_REGISTER); WRITE_PORT_UCHAR(Address + MODEM_CONTROL_REGISTER, SERIAL_MCR_LOOP); WRITE_PORT_UCHAR(Address + MODEM_CONTROL_REGISTER, SERIAL_MCR_LOOP); if (!(READ_PORT_UCHAR(Address + MODEM_STATUS_REGISTER) & (SERIAL_MSR_CTS | SERIAL_MSR_DSR | SERIAL_MSR_RI | SERIAL_MSR_DCD))) { WRITE_PORT_UCHAR(Address + MODEM_CONTROL_REGISTER, (SERIAL_MCR_OUT1 | SERIAL_MCR_LOOP)); if (READ_PORT_UCHAR(Address + MODEM_STATUS_REGISTER) & SERIAL_MSR_RI) { WRITE_PORT_UCHAR(Address + MODEM_CONTROL_REGISTER, Old); return TRUE; } } WRITE_PORT_UCHAR(Address + MODEM_CONTROL_REGISTER, Old); return FALSE; } UCHAR NTAPI CpReadLsr(IN PCPPORT Port, IN UCHAR ExpectedValue) { UCHAR Lsr, Msr; /* Read the LSR and check if the expected value is present */ Lsr = READ_PORT_UCHAR(Port->Address + LINE_STATUS_REGISTER); if (!(Lsr & ExpectedValue)) { /* Check the MSR for ring indicator toggle */ Msr = READ_PORT_UCHAR(Port->Address + MODEM_STATUS_REGISTER); /* If the indicator reaches 3, we've seen this on/off twice */ RingIndicator |= (Msr & SERIAL_MSR_RI) ? 1 : 2; if (RingIndicator == 3) Port->Flags |= CPPORT_FLAG_MODEM_CONTROL; } return Lsr; } VOID NTAPI CpSetBaud(IN PCPPORT Port, IN ULONG Rate) { UCHAR Lcr; USHORT Mode; /* Add DLAB */ Lcr = READ_PORT_UCHAR(Port->Address + LINE_CONTROL_REGISTER); WRITE_PORT_UCHAR(Port->Address + LINE_CONTROL_REGISTER, Lcr | SERIAL_LCR_DLAB); /* Set baud rate */ Mode = 115200 / Rate; WRITE_PORT_UCHAR(Port->Address + DIVISOR_LATCH_MSB, (UCHAR)((Mode >> 8) & 0xff)); WRITE_PORT_UCHAR(Port->Address + DIVISOR_LATCH_LSB, (UCHAR)(Mode & 0xff)); /* Reset DLAB and set 8 data bits, 1 stop bit, no parity, no break */ WRITE_PORT_UCHAR(Port->Address + LINE_CONTROL_REGISTER, SERIAL_8_DATA | SERIAL_1_STOP | SERIAL_NONE_PARITY); /* Save baud rate in port */ Port->Baud = Rate; } USHORT NTAPI CpGetByte(IN PCPPORT Port, IN PUCHAR Byte, IN BOOLEAN Wait, IN BOOLEAN Poll) { UCHAR Lsr; ULONG i; /* Handle early read-before-init */ if (!Port->Address) return CP_GET_NODATA; /* If "wait" mode enabled, spin many times, otherwise attempt just once */ i = Wait ? 204800 : 1; while (i--) { /* Read LSR for data ready */ Lsr = CpReadLsr(Port, SERIAL_LSR_DR); if ((Lsr & SERIAL_LSR_DR) == SERIAL_LSR_DR) { /* If an error happened, clear the byte and fail */ if (Lsr & (SERIAL_LSR_FE | SERIAL_LSR_PE)) { *Byte = 0; return CP_GET_ERROR; } /* If only polling was requested by caller, return now */ if (Poll) return CP_GET_SUCCESS; /* Otherwise read the byte and return it */ *Byte = READ_PORT_UCHAR(Port->Address + RECEIVE_BUFFER_REGISTER); /* Handle CD if port is in modem control mode */ if (Port->Flags & CPPORT_FLAG_MODEM_CONTROL) { /* Not implemented yet */ DPRINT1("CP: CPPORT_FLAG_MODEM_CONTROL unexpected\n"); } /* Byte was read */ return CP_GET_SUCCESS; } } /* Reset LSR, no data was found */ CpReadLsr(Port, 0); return CP_GET_NODATA; } VOID NTAPI CpPutByte(IN PCPPORT Port, IN UCHAR Byte) { /* Check if port is in modem control to handle CD */ while (Port->Flags & CPPORT_FLAG_MODEM_CONTROL) { /* Not implemented yet */ DPRINT1("CP: CPPORT_FLAG_MODEM_CONTROL unexpected\n"); } /* Wait for LSR to say we can go ahead */ while (!(CpReadLsr(Port, SERIAL_LSR_THRE) & SERIAL_LSR_THRE)); /* Send the byte */ WRITE_PORT_UCHAR(Port->Address + RECEIVE_BUFFER_REGISTER, Byte); }