Chloe M.
106 lines
2.7 KiB
C
106 lines
2.7 KiB
C
/*
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* Copyright (c) 2026, Chloe M.
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* Provided under the BSD-3 clause.
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*
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* Description: serial interface
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* Author: Chloe M.
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*/
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#include <hal/serial.h>
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#include <machine/pio.h>
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#include <stdef.h>
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/* Channel port numbers */
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#define UART_COM1 0x3F8
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#define UART_COM2 0x2F8
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#define UART_COM3 0x3E8
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#define UART_COM4 0x2E8
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#define UART_COM5 0x5F8
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#define UART_COM6 0x4F8
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#define UART_COM7 0x5E8
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#define UART_COM8 0x4E8
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/* Register offsets */
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#define UART_REG(OFFSET) (UART_COM1 + OFFSET)
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#define UART_REG_FCR UART_REG(2) /* FIFO Control Register */
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#define UART_REG_LCR UART_REG(3) /* Line Control Register */
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#define UART_REG_MCR UART_REG(4) /* MODEM Control Register */
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#define UART_REG_LSR UART_REG(5) /* Line Status Register */
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#define UART_REG_MSR UART_REG(6) /* MODEM Status Register */
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#define UART_REG_SR UART_REG(7) /* Scratch Register */
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/* Registers when LCR.DLAB=0 */
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#define UART_REG_RBR UART_REG(0) /* Receiver Buffer Register */
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#define UART_REG_THR UART_REG(0) /* Transmitter Holding Register */
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#define UART_REG_IER UART_REG(1) /* Interrupt Enable Register */
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/* Registers when LCR.DLAB=1 */
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#define UART_REG_DLL UART_REG(0) /* Divisor Latch Low */
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#define UART_REG_DLH UART_REG(1) /* Divisor Latch High */
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#define UART_LCR_WLS0 BIT(0) /* Word Length Select Bit 0 */
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#define UART_LCR_WLS1 BIT(1) /* Word Length Select Bit 1 */
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#define UART_LCR_DLAB BIT(7) /* Divisor Latch Access Bit*/
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#define UART_MCR_DTR BIT(0) /* Data Terminal Ready*/
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#define UART_MCR_LOOP BIT(4) /* Loop */
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#define UART_LSR_THRE BIT(5) /* Transmitter Holding Register */
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#define UART_DIVISOR(RATE) (115200 / RATE)
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static inline BOOLEAN
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UartTxEmpty(VOID)
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{
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return ISSET(UART_REG_LSR, UART_LSR_THRE) != 0;
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}
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VOID
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HalSerialWrite(const CHAR *Data, USIZE Length)
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{
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if (Data == NULL) {
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return;
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}
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while (!UartTxEmpty()) {
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ASMV("pause");
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}
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for (USIZE Index = 0; Index < Length; ++Index) {
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MdOutb(UART_REG_THR, Data[Index]);
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}
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}
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ST_STATUS
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HalSerialInit(VOID)
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{
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/* Disable interrupts */
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MdOutb(UART_REG_IER, 0x00);
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/* Set DLAB to set baud rate */
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MdOutb(UART_REG_LCR, UART_LCR_DLAB);
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/* Set speed to 57600 baud */
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MdOutb(UART_REG_DLL, UART_DIVISOR(57600));
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MdOutb(UART_REG_IER, 0x00);
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/* Set word size to 8 bits and clear DLAB */
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MdOutb(UART_REG_LCR, UART_LCR_WLS0 | UART_LCR_WLS1);
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/* Disable FIFOs for now... (TODO: Use them) */
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MdOutb(UART_REG_FCR, 0x00);
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/* Test chip in loopback mode */
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MdOutb(UART_REG_MCR, UART_MCR_LOOP);
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MdOutb(UART_REG_THR, 0xF0);
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if (MdInb(UART_REG_RBR != 0xF0))
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return -1;
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/*
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* Mark the data terminal ready and clear
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* loopback mode.
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*/
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MdOutb(UART_REG_MCR, UART_MCR_DTR);
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return 0;
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}
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