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 #include "of.h"
  19
  20 #define UART_DLL        0       /* Out: Divisor Latch Low */
  21 #define UART_DLM        1       /* Out: Divisor Latch High */
  22 #define UART_FCR        2       /* Out: FIFO Control Register */
  23 #define UART_LCR        3       /* Out: Line Control Register */
  24 #define UART_MCR        4       /* Out: Modem Control Register */
  25 #define UART_LSR        5       /* In:  Line Status Register */
  26 #define UART_LSR_THRE   0x20    /* Transmit-hold-register empty */
  27 #define UART_LSR_DR     0x01    /* Receiver data ready */
  28 #define UART_MSR        6       /* In:  Modem Status Register */
  29 #define UART_SCR        7       /* I/O: Scratch Register */
  30
  31 static unsigned char *reg_base;
  32 static u32 reg_shift;
  33
  34 static int ns16550_open(void)
  35 {
  36         out_8(reg_base + (UART_FCR << reg_shift), 0x06);
  37         return 0;
  38 }
  39
  40 static void ns16550_putc(unsigned char c)
  41 {
  42         while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_THRE) == 0);
  43         out_8(reg_base, c);
  44 }
  45
  46 static unsigned char ns16550_getc(void)
  47 {
  48         while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) == 0);
  49         return in_8(reg_base);
  50 }
  51
  52 static u8 ns16550_tstc(void)
  53 {
  54         return ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) != 0);
  55 }
  56
  57 int ns16550_console_init(void *devp, struct serial_console_data *scdp)
  58 {
  59         int n;
  60         u32 reg_offset;
  61
  62         if (dt_get_virtual_reg(devp, (void **)&reg_base, 1) < 1) {
  63                 printf("virt reg parse fail...\r\n");
  64                 return -1;
  65         }
  66
  67         n = getprop(devp, "reg-offset", &reg_offset, sizeof(reg_offset));
  68         if (n == sizeof(reg_offset))
  69                 reg_base += be32_to_cpu(reg_offset);
  70
  71         n = getprop(devp, "reg-shift", &reg_shift, sizeof(reg_shift));
  72         if (n != sizeof(reg_shift))
  73                 reg_shift = 0;
  74         else
  75                 reg_shift = be32_to_cpu(reg_shift);
  76
  77         scdp->open = ns16550_open;
  78         scdp->putc = ns16550_putc;
  79         scdp->getc = ns16550_getc;
  80         scdp->tstc = ns16550_tstc;
  81         scdp->close = NULL;
  82
  83         return 0;
  84 }