| /* SPDX-License-Identifier: GPL-2.0-only */ |
| |
| #include <arch/io.h> |
| #include <boot/coreboot_tables.h> |
| #include <commonlib/bsd/helpers.h> |
| #include <console/uart.h> |
| #include <stdint.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)); |
| } |
| |
| enum cb_err fill_lb_serial(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(); |
| |
| return CB_SUCCESS; |
| } |