drivers/serial/altera_uart.c

   1 /*
   2  * (C) Copyright 2004, Psyent Corporation <www.psyent.com>
   3  * Scott McNutt <smcnutt@psyent.com>
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8
   9 #include <common.h>
  10 #include <watchdog.h>
  11 #include <asm/io.h>
  12 #include <nios2-io.h>
  13 #include <linux/compiler.h>
  14 #include <serial.h>
  15
  16 DECLARE_GLOBAL_DATA_PTR;
  17
  18 /*------------------------------------------------------------------
  19  * UART the serial port
  20  *-----------------------------------------------------------------*/
  21
  22 static nios_uart_t *uart = (nios_uart_t *) CONFIG_SYS_NIOS_CONSOLE;
  23
  24 #if defined(CONFIG_SYS_NIOS_FIXEDBAUD)
  25
  26 /*
  27  * Everything's already setup for fixed-baud PTF
  28  * assignment
  29  */
  30 static void altera_serial_setbrg(void)
  31 {
  32 }
  33
  34 static int altera_serial_init(void)
  35 {
  36         return 0;
  37 }
  38
  39 #else
  40
  41 static void altera_serial_setbrg(void)
  42 {
  43         unsigned div;
  44
  45         div = (CONFIG_SYS_CLK_FREQ/gd->baudrate)-1;
  46         writel (div, &uart->divisor);
  47 }
  48
  49 static int altera_serial_init(void)
  50 {
  51         serial_setbrg();
  52         return 0;
  53 }
  54
  55 #endif /* CONFIG_SYS_NIOS_FIXEDBAUD */
  56
  57 /*-----------------------------------------------------------------------
  58  * UART CONSOLE
  59  *---------------------------------------------------------------------*/
  60 static void altera_serial_putc(char c)
  61 {
  62         if (c == '\n')
  63                 serial_putc ('\r');
  64         while ((readl (&uart->status) & NIOS_UART_TRDY) == 0)
  65                 WATCHDOG_RESET ();
  66         writel ((unsigned char)c, &uart->txdata);
  67 }
  68
  69 static int altera_serial_tstc(void)
  70 {
  71         return (readl (&uart->status) & NIOS_UART_RRDY);
  72 }
  73
  74 static int altera_serial_getc(void)
  75 {
  76         while (serial_tstc () == 0)
  77                 WATCHDOG_RESET ();
  78         return (readl (&uart->rxdata) & 0x00ff );
  79 }
  80
  81 static struct serial_device altera_serial_drv = {
  82         .name   = "altera_serial",
  83         .start  = altera_serial_init,
  84         .stop   = NULL,
  85         .setbrg = altera_serial_setbrg,
  86         .putc   = altera_serial_putc,
  87         .puts   = default_serial_puts,
  88         .getc   = altera_serial_getc,
  89         .tstc   = altera_serial_tstc,
  90 };
  91
  92 void altera_serial_initialize(void)
  93 {
  94         serial_register(&altera_serial_drv);
  95 }
  96
  97 __weak struct serial_device *default_serial_console(void)
  98 {
  99         return &altera_serial_drv;
 100 }