drivers/serial/altera_jtag_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 #include <common.h>
   9 #include <watchdog.h>
  10 #include <asm/io.h>
  11 #include <nios2-io.h>
  12 #include <linux/compiler.h>
  13 #include <serial.h>
  14
  15 DECLARE_GLOBAL_DATA_PTR;
  16
  17 /*------------------------------------------------------------------
  18  * JTAG acts as the serial port
  19  *-----------------------------------------------------------------*/
  20 static nios_jtag_t *jtag = (nios_jtag_t *)CONFIG_SYS_NIOS_CONSOLE;
  21
  22 static void altera_jtag_serial_setbrg(void)
  23 {
  24 }
  25
  26 static int altera_jtag_serial_init(void)
  27 {
  28         return 0;
  29 }
  30
  31 static void altera_jtag_serial_putc(char c)
  32 {
  33         while (1) {
  34                 unsigned st = readl(&jtag->control);
  35                 if (NIOS_JTAG_WSPACE(st))
  36                         break;
  37 #ifdef CONFIG_ALTERA_JTAG_UART_BYPASS
  38                 if (!(st & NIOS_JTAG_AC)) /* no connection */
  39                         return;
  40 #endif
  41                 WATCHDOG_RESET();
  42         }
  43         writel ((unsigned char)c, &jtag->data);
  44 }
  45
  46 static int altera_jtag_serial_tstc(void)
  47 {
  48         return ( readl (&jtag->control) & NIOS_JTAG_RRDY);
  49 }
  50
  51 static int altera_jtag_serial_getc(void)
  52 {
  53         int c;
  54         unsigned val;
  55
  56         while (1) {
  57                 WATCHDOG_RESET ();
  58                 val = readl (&jtag->data);
  59                 if (val & NIOS_JTAG_RVALID)
  60                         break;
  61         }
  62         c = val & 0x0ff;
  63         return (c);
  64 }
  65
  66 static struct serial_device altera_jtag_serial_drv = {
  67         .name   = "altera_jtag_uart",
  68         .start  = altera_jtag_serial_init,
  69         .stop   = NULL,
  70         .setbrg = altera_jtag_serial_setbrg,
  71         .putc   = altera_jtag_serial_putc,
  72         .puts   = default_serial_puts,
  73         .getc   = altera_jtag_serial_getc,
  74         .tstc   = altera_jtag_serial_tstc,
  75 };
  76
  77 void altera_jtag_serial_initialize(void)
  78 {
  79         serial_register(&altera_jtag_serial_drv);
  80 }
  81
  82 __weak struct serial_device *default_serial_console(void)
  83 {
  84         return &altera_jtag_serial_drv;
  85 }