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/* 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();
lb_add_serial(&serial, data);
lb_add_console(LB_TAG_CONSOLE_SERIAL8250, data);
}
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