ns16550.c

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/*
 * 16550 serial console support.
 *
 * Original copied from <file:arch/ppc/boot/common/ns16550.c>
 * (which had no copyright)
 * Modifications: 2006 (c) MontaVista Software, Inc.
 *
 * Modified by: Mark A. Greer <[email protected]>
 */
#include <stdarg.h>
#include <stddef.h>
#include "types.h"
#include "string.h"
#include "stdio.h"
#include "io.h"
#include "ops.h"

#define UART_DLL    0   /* Out: Divisor Latch Low */
#define UART_DLM    1   /* Out: Divisor Latch High */
#define UART_FCR    2   /* Out: FIFO Control Register */
#define UART_LCR    3   /* Out: Line Control Register */
#define UART_MCR    4   /* Out: Modem Control Register */
#define UART_LSR    5   /* In:  Line Status Register */
#define UART_LSR_THRE   0x20    /* Transmit-hold-register empty */
#define UART_LSR_DR 0x01    /* Receiver data ready */
#define UART_MSR    6   /* In:  Modem Status Register */
#define UART_SCR    7   /* I/O: Scratch Register */

static unsigned char *reg_base;
static u32 reg_shift;

static int ns16550_open(void)
{
    out_8(reg_base + (UART_FCR << reg_shift), 0x06);
    return 0;
}

static void ns16550_putc(unsigned char c)
{
    while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_THRE) == 0);
    out_8(reg_base, c);
}

static unsigned char ns16550_getc(void)
{
    while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) == 0);
    return in_8(reg_base);
}

static u8 ns16550_tstc(void)
{
    return ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) != 0);
}

int ns16550_console_init(void *devp, struct serial_console_data *scdp)
{
    int n;
    u32 reg_offset;

    if (dt_get_virtual_reg(devp, (void **)&reg_base, 1) < 1)
        return -1;

    n = getprop(devp, "reg-offset", &reg_offset, sizeof(reg_offset));
    if (n == sizeof(reg_offset))
        reg_base += reg_offset;

    n = getprop(devp, "reg-shift", &reg_shift, sizeof(reg_shift));
    if (n != sizeof(reg_shift))
        reg_shift = 0;

    scdp->open = ns16550_open;
    scdp->putc = ns16550_putc;
    scdp->getc = ns16550_getc;
    scdp->tstc = ns16550_tstc;
    scdp->close = NULL;

    return 0;
}