/* SPDX-License-Identifier: GPL-2.0-only */ #include <arch/io.h> #include <boot/coreboot_tables.h> #include <console/uart.h> #include "uart8250reg.h" /* Should support 8250, 16450, 16550, 16550A type UARTs */ /* Expected character delay at 1200bps is 9ms for a working UART * and no flow-control. Assume UART as stuck if shift register * or FIFO takes more than 50ms per character to appear empty. * * Estimated that inb() from UART takes 1 microsecond. */ #define SINGLE_CHAR_TIMEOUT (50 * 1000) #define FIFO_TIMEOUT (16 * SINGLE_CHAR_TIMEOUT) static int uart8250_can_tx_byte(unsigned int base_port) { return inb(base_port + UART8250_LSR) & UART8250_LSR_THRE; } static void uart8250_tx_byte(unsigned int base_port, unsigned char data) { unsigned long int i = SINGLE_CHAR_TIMEOUT; while (i-- && !uart8250_can_tx_byte(base_port)); outb(data, base_port + UART8250_TBR); } static void uart8250_tx_flush(unsigned int base_port) { unsigned long int i = FIFO_TIMEOUT; while (i-- && !(inb(base_port + UART8250_LSR) & UART8250_LSR_TEMT)); } static int uart8250_can_rx_byte(unsigned int base_port) { return inb(base_port + UART8250_LSR) & UART8250_LSR_DR; } static unsigned char uart8250_rx_byte(unsigned int base_port) { unsigned long int i = SINGLE_CHAR_TIMEOUT; while (i && !uart8250_can_rx_byte(base_port)) i--; if (i) return inb(base_port + UART8250_RBR); else return 0x0; } static void uart8250_init(unsigned int base_port, unsigned int divisor) { /* Disable interrupts */ outb(0x0, base_port + UART8250_IER); /* Enable FIFOs */ outb(UART8250_FCR_FIFO_EN, base_port + UART8250_FCR); /* assert DTR and RTS so the other end is happy */ outb(UART8250_MCR_DTR | UART8250_MCR_RTS, base_port + UART8250_MCR); /* DLAB on */ outb(UART8250_LCR_DLAB | CONFIG_TTYS0_LCS, base_port + UART8250_LCR); /* Set Baud Rate Divisor. 12 ==> 9600 Baud */ outb(divisor & 0xFF, base_port + UART8250_DLL); outb((divisor >> 8) & 0xFF, base_port + UART8250_DLM); /* Set to 3 for 8N1 */ outb(CONFIG_TTYS0_LCS, base_port + UART8250_LCR); } static const unsigned int bases[] = { 0x3f8, 0x2f8, 0x3e8, 0x2e8 }; uintptr_t uart_platform_base(unsigned int idx) { if (idx < ARRAY_SIZE(bases)) return bases[idx]; return 0; } void uart_init(unsigned int idx) { if (!CONFIG(DRIVERS_UART_8250IO_SKIP_INIT)) { unsigned int div; div = uart_baudrate_divisor(get_uart_baudrate(), uart_platform_refclk(), uart_input_clock_divider()); uart8250_init(uart_platform_base(idx), div); } } void uart_tx_byte(unsigned int idx, unsigned char data) { uart8250_tx_byte(uart_platform_base(idx), data); } unsigned char uart_rx_byte(unsigned int idx) { return uart8250_rx_byte(uart_platform_base(idx)); } void uart_tx_flush(unsigned int idx) { uart8250_tx_flush(uart_platform_base(idx)); } void uart_fill_lb(void *data) { struct lb_serial serial; serial.type = LB_SERIAL_TYPE_IO_MAPPED; serial.baseaddr = uart_platform_base(CONFIG_UART_FOR_CONSOLE); serial.baud = get_uart_baudrate(); serial.regwidth = 1; serial.input_hertz = uart_platform_refclk(); serial.uart_pci_addr = CONFIG_UART_PCI_ADDR; lb_add_serial(&serial, data); lb_add_console(LB_TAG_CONSOLE_SERIAL8250, data); }