drivers/serial/altera_jtag_uart.c

   1 /*
   2  * (C) Copyright 2004, Psyent Corporation <www.psyent.com>
   3  * Scott McNutt <smcnutt@psyent.com>
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  */
  23
  24 #include <common.h>
  25 #include <watchdog.h>
  26 #include <asm/io.h>
  27 #include <nios2-io.h>
  28 #include <linux/compiler.h>
  29 #include <serial.h>
  30
  31 DECLARE_GLOBAL_DATA_PTR;
  32
  33 /*------------------------------------------------------------------
  34  * JTAG acts as the serial port
  35  *-----------------------------------------------------------------*/
  36 static nios_jtag_t *jtag = (nios_jtag_t *)CONFIG_SYS_NIOS_CONSOLE;
  37
  38 static void altera_jtag_serial_setbrg(void)
  39 {
  40 }
  41
  42 static int altera_jtag_serial_init(void)
  43 {
  44         return 0;
  45 }
  46
  47 static void altera_jtag_serial_putc(char c)
  48 {
  49         while (1) {
  50                 unsigned st = readl(&jtag->control);
  51                 if (NIOS_JTAG_WSPACE(st))
  52                         break;
  53 #ifdef CONFIG_ALTERA_JTAG_UART_BYPASS
  54                 if (!(st & NIOS_JTAG_AC)) /* no connection */
  55                         return;
  56 #endif
  57                 WATCHDOG_RESET();
  58         }
  59         writel ((unsigned char)c, &jtag->data);
  60 }
  61
  62 static int altera_jtag_serial_tstc(void)
  63 {
  64         return ( readl (&jtag->control) & NIOS_JTAG_RRDY);
  65 }
  66
  67 static int altera_jtag_serial_getc(void)
  68 {
  69         int c;
  70         unsigned val;
  71
  72         while (1) {
  73                 WATCHDOG_RESET ();
  74                 val = readl (&jtag->data);
  75                 if (val & NIOS_JTAG_RVALID)
  76                         break;
  77         }
  78         c = val & 0x0ff;
  79         return (c);
  80 }
  81
  82 static struct serial_device altera_jtag_serial_drv = {
  83         .name   = "altera_jtag_uart",
  84         .start  = altera_jtag_serial_init,
  85         .stop   = NULL,
  86         .setbrg = altera_jtag_serial_setbrg,
  87         .putc   = altera_jtag_serial_putc,
  88         .puts   = default_serial_puts,
  89         .getc   = altera_jtag_serial_getc,
  90         .tstc   = altera_jtag_serial_tstc,
  91 };
  92
  93 void altera_jtag_serial_initialize(void)
  94 {
  95         serial_register(&altera_jtag_serial_drv);
  96 }
  97
  98 __weak struct serial_device *default_serial_console(void)
  99 {
 100         return &altera_jtag_serial_drv;
 101 }