LXR linux/arch/powerpc/boot/ns16550.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * 16550 serial console support.
   4 *
   5 * Original copied from <file:arch/ppc/boot/common/ns16550.c>
   6 * (which had no copyright)
   7 * Modifications: 2006 (c) MontaVista Software, Inc.
   8 *
   9 * Modified by: Mark A. Greer <mgreer@mvista.com>
  10 */
  11#include <stdarg.h>
  12#include <stddef.h>
  13#include "types.h"
  14#include "string.h"
  15#include "stdio.h"
  16#include "io.h"
  17#include "ops.h"
  18
  19#define UART_DLL        0       /* Out: Divisor Latch Low */
  20#define UART_DLM        1       /* Out: Divisor Latch High */
  21#define UART_FCR        2       /* Out: FIFO Control Register */
  22#define UART_LCR        3       /* Out: Line Control Register */
  23#define UART_MCR        4       /* Out: Modem Control Register */
  24#define UART_LSR        5       /* In:  Line Status Register */
  25#define UART_LSR_THRE   0x20    /* Transmit-hold-register empty */
  26#define UART_LSR_DR     0x01    /* Receiver data ready */
  27#define UART_MSR        6       /* In:  Modem Status Register */
  28#define UART_SCR        7       /* I/O: Scratch Register */
  29
  30static unsigned char *reg_base;
  31static u32 reg_shift;
  32
  33static int ns16550_open(void)
  34{
  35        out_8(reg_base + (UART_FCR << reg_shift), 0x06);
  36        return 0;
  37}
  38
  39static void ns16550_putc(unsigned char c)
  40{
  41        while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_THRE) == 0);
  42        out_8(reg_base, c);
  43}
  44
  45static unsigned char ns16550_getc(void)
  46{
  47        while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) == 0);
  48        return in_8(reg_base);
  49}
  50
  51static u8 ns16550_tstc(void)
  52{
  53        return ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) != 0);
  54}
  55
  56int ns16550_console_init(void *devp, struct serial_console_data *scdp)
  57{
  58        int n;
  59        u32 reg_offset;
  60
  61        if (dt_get_virtual_reg(devp, (void **)&reg_base, 1) < 1)
  62                return -1;
  63
  64        n = getprop(devp, "reg-offset", &reg_offset, sizeof(reg_offset));
  65        if (n == sizeof(reg_offset))
  66                reg_base += reg_offset;
  67
  68        n = getprop(devp, "reg-shift", &reg_shift, sizeof(reg_shift));
  69        if (n != sizeof(reg_shift))
  70                reg_shift = 0;
  71
  72        scdp->open = ns16550_open;
  73        scdp->putc = ns16550_putc;
  74        scdp->getc = ns16550_getc;
  75        scdp->tstc = ns16550_tstc;
  76        scdp->close = NULL;
  77
  78        return 0;
  79}
  80