From abced67cbb8a19369ae1a5aaafd6318f0b2ee069 Mon Sep 17 00:00:00 2001 From: Ian Moffett Date: Sat, 6 Jul 2024 01:11:44 -0400 Subject: kernel/amd64: Add 8250 UART driver Signed-off-by: Ian Moffett --- sys/arch/amd64/amd64/uart.c | 81 +++++++++++++++++++++++++++++++++++++++++++ sys/include/arch/amd64/uart.h | 36 +++++++++++++++++++ 2 files changed, 117 insertions(+) create mode 100644 sys/arch/amd64/amd64/uart.c create mode 100644 sys/include/arch/amd64/uart.h (limited to 'sys') diff --git a/sys/arch/amd64/amd64/uart.c b/sys/arch/amd64/amd64/uart.c new file mode 100644 index 0000000..9c78434 --- /dev/null +++ b/sys/arch/amd64/amd64/uart.c @@ -0,0 +1,81 @@ +/* + * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of Hyra nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#include +#include +#include + +#define UART_COM1 0x3F8 +#define UART_REG(OFFSET) (UART_COM1 + OFFSET) + +static inline bool +uart_transmit_empty(void) +{ + return ISSET(UART_REG(5), BIT(5)); +} + +void +uart_write(char byte) +{ + while (!uart_transmit_empty()); + outb(UART_COM1, byte); +} + +int +uart_init(void) +{ + /* Disable interrupts */ + outb(UART_REG(1), 0x00); + + /* Set DLAB to set baud rate */ + outb(UART_REG(3), 0x80); + + /* Set rate to 57600 baud */ + outb(UART_REG(0), 0x02); + outb(UART_REG(1), 0x00); + + /* Set data word length to 8 bits and clear DLAB */ + outb(UART_REG(3), 0x03); + + /* Disable FIFOs for now... (TODO: Use them) */ + outb(UART_REG(2), 0x00); + + /* Test chip with loopback mode */ + outb(UART_REG(4), 0x10); + outb(UART_REG(0), 0xF0); + if (inb(UART_REG(0) != 0xF0)) + return -1; + + /* + * Mark the data terminal ready and clear + * loopback mode. + */ + outb(UART_REG(4), 0x01); + return 0; +} diff --git a/sys/include/arch/amd64/uart.h b/sys/include/arch/amd64/uart.h new file mode 100644 index 0000000..cf85635 --- /dev/null +++ b/sys/include/arch/amd64/uart.h @@ -0,0 +1,36 @@ +/* + * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of Hyra nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#ifndef _MACHINE_UART_H_ +#define _MACHINE_UART_H_ + +int uart_init(void); +void uart_write(char byte); + +#endif /* !_MACHINE_UART_H_ */ -- cgit v1.2.3