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
  30 static unsigned char *reg_base;
  31 static u32 reg_shift;
  32
  33 static int ns16550_open(void)
  34 {
  35         out_8(reg_base + (UART_FCR << reg_shift), 0x06);
  36         return 0;
  37 }
  38
  39 static 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
  45 static 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
  51 static u8 ns16550_tstc(void)
  52 {
  53         return ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) != 0);
  54 }
  55
  56 int 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 }