uart.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <device/mmio.h>
#include <boot/coreboot_tables.h>
#include <console/uart.h>
#include <soc/clk.h>
#include <soc/cpu.h>
#include <soc/periph.h>
#include <soc/uart.h>
#include <types.h>
 
#define RX_FIFO_COUNT_MASK      0xff
#define RX_FIFO_FULL_MASK       (1 << 8)
#define TX_FIFO_FULL_MASK       (1 << 24)
 
static void serial_setbrg_dev(struct s5p_uart *uart)
{
        u32 uclk;
        u32 val;
 
        // All UARTs share the same clock.
        uclk = clock_get_periph_rate(PERIPH_ID_UART3);
        val = uclk / get_uart_baudrate();
 
        write32(&uart->ubrdiv, val / 16 - 1);
}
 
/*
 * Initialise the serial port with the given baudrate. The settings
 * are always 8 data bits, no parity, 1 stop bit, no start bits.
 */
static void exynos5_init_dev(struct s5p_uart *uart)
{
        /* enable FIFOs */
        write32(&uart->ufcon, 0x1);
        write32(&uart->umcon, 0);
        /* 8N1 */
        write32(&uart->ulcon, 0x3);
        /* No interrupts, no DMA, pure polling */
        write32(&uart->ucon, 0x245);
 
        serial_setbrg_dev(uart);
}
 
static int exynos5_uart_err_check(struct s5p_uart *uart, int op)
{
        unsigned int mask;
 
        /*
         * UERSTAT
         * Break Detect [3]
         * Frame Err    [2] : receive operation
         * Parity Err   [1] : receive operation
         * Overrun Err  [0] : receive operation
         */
        if (op)
                mask = 0x8;
        else
                mask = 0xf;
 
        return read32(&uart->uerstat) & mask;
}
 
/*
 * Read a single byte from the serial port. Returns 1 on success, 0
 * otherwise. When the function is successful, the character read is
 * written into its argument c.
 */
static unsigned char exynos5_uart_rx_byte(struct s5p_uart *uart)
{
        /* wait for character to arrive */
        while (!(read32(&uart->ufstat) & (RX_FIFO_COUNT_MASK |
                                         RX_FIFO_FULL_MASK))) {
                if (exynos5_uart_err_check(uart, 0))
                        return 0;
        }
 
        return read8(&uart->urxh) & 0xff;
}
 
/*
 * Output a single byte to the serial port.
 */
static void exynos5_uart_tx_byte(struct s5p_uart *uart, unsigned char data)
{
        /* wait for room in the tx FIFO */
        while ((read32(&uart->ufstat) & TX_FIFO_FULL_MASK)) {
                if (exynos5_uart_err_check(uart, 1))
                        return;
        }
 
        write8(&uart->utxh, data);
}
 
uintptr_t uart_platform_base(unsigned int idx)
{
        if (idx < 4)
                return 0x12c00000 + idx * 0x10000;
        else
                return 0;
}
 
void uart_init(unsigned int idx)
{
        struct s5p_uart *uart = uart_platform_baseptr(idx);
        exynos5_init_dev(uart);
}
 
unsigned char uart_rx_byte(unsigned int idx)
{
        struct s5p_uart *uart = uart_platform_baseptr(idx);
        return exynos5_uart_rx_byte(uart);
}
 
void uart_tx_byte(unsigned int idx, unsigned char data)
{
        struct s5p_uart *uart = uart_platform_baseptr(idx);
        exynos5_uart_tx_byte(uart, data);
}
 
void uart_tx_flush(unsigned int idx)
{
        /* Exynos5250 implements this too. */
}
 
void uart_fill_lb(void *data)
{
        struct lb_serial serial;
        serial.type = LB_SERIAL_TYPE_MEMORY_MAPPED;
        serial.baseaddr = uart_platform_base(CONFIG_UART_FOR_CONSOLE);
        serial.baud = get_uart_baudrate();
        serial.regwidth = 4;
        serial.input_hertz = uart_platform_refclk();
        serial.uart_pci_addr = 0;
        lb_add_serial(&serial, data);
 
        lb_add_console(LB_TAG_CONSOLE_SERIAL8250MEM, data);
}