LXR uboot/drivers/serial/opencores

   1/*
   2 * Copyright 2010, Renato Andreola <renato.andreola@imagos.it>
   3 *
   4 * See file CREDITS for list of people who contributed to this
   5 * project.
   6 *
   7 * This program is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License as
   9 * published by the Free Software Foundation; either version 2 of
  10 * the License, or (at your option) any later version.
  11 *
  12 * This program is distributed in the hope that it will be useful,
  13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 * GNU General Public License for more details.
  16 *
  17 * You should have received a copy of the GNU General Public License
  18 * along with this program; if not, write to the Free Software
  19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  20 * MA 02111-1307 USA
  21 */
  22
  23#include <common.h>
  24#include <watchdog.h>
  25#include <asm/io.h>
  26#include <nios2-yanu.h>
  27
  28DECLARE_GLOBAL_DATA_PTR;
  29
  30/*-----------------------------------------------------------------*/
  31/* YANU Imagos serial port */
  32/*-----------------------------------------------------------------*/
  33
  34static yanu_uart_t *uart = (yanu_uart_t *)CONFIG_SYS_NIOS_CONSOLE;
  35
  36#if defined(CONFIG_SYS_NIOS_FIXEDBAUD)
  37
  38/* Everything's already setup for fixed-baud PTF assignment*/
  39
  40void serial_setbrg (void)
  41{
  42        int n, k;
  43        const unsigned max_uns = 0xFFFFFFFF;
  44        unsigned best_n, best_m, baud;
  45
  46        /* compute best N and M couple */
  47        best_n = YANU_MAX_PRESCALER_N;
  48        for (n = YANU_MAX_PRESCALER_N; n >= 0; n--) {
  49                if ((unsigned)CONFIG_SYS_CLK_FREQ / (1 << (n + 4)) >=
  50                    (unsigned)CONFIG_BAUDRATE) {
  51                        best_n = n;
  52                        break;
  53                }
  54        }
  55        for (k = 0;; k++) {
  56                if ((unsigned)CONFIG_BAUDRATE <= (max_uns >> (15+n-k)))
  57                        break;
  58        }
  59        best_m =
  60            ((unsigned)CONFIG_BAUDRATE * (1 << (15 + n - k))) /
  61            ((unsigned)CONFIG_SYS_CLK_FREQ >> k);
  62
  63        baud = best_m + best_n * YANU_BAUDE;
  64        writel(baud, &uart->baud);
  65
  66        return;
  67}
  68
  69#else
  70
  71void serial_setbrg (void)
  72{
  73        int n, k;
  74        const unsigned max_uns = 0xFFFFFFFF;
  75        unsigned best_n, best_m, baud;
  76
  77        /* compute best N and M couple */
  78        best_n = YANU_MAX_PRESCALER_N;
  79        for (n = YANU_MAX_PRESCALER_N; n >= 0; n--) {
  80                if ((unsigned)CONFIG_SYS_CLK_FREQ / (1 << (n + 4)) >=
  81                    gd->baudrate) {
  82                        best_n = n;
  83                        break;
  84                }
  85        }
  86        for (k = 0;; k++) {
  87                if (gd->baudrate <= (max_uns >> (15+n-k)))
  88                        break;
  89        }
  90        best_m =
  91            (gd->baudrate * (1 << (15 + n - k))) /
  92            ((unsigned)CONFIG_SYS_CLK_FREQ >> k);
  93
  94        baud = best_m + best_n * YANU_BAUDE;
  95        writel(baud, &uart->baud);
  96
  97        return;
  98}
  99
 100
 101#endif /* CONFIG_SYS_NIOS_FIXEDBAUD */
 102
 103int serial_init (void)
 104{
 105        unsigned action,control;
 106
 107        /* status register cleanup */
 108        action =  YANU_ACTION_RRRDY     |
 109                YANU_ACTION_RTRDY       |
 110                YANU_ACTION_ROE         |
 111                YANU_ACTION_RBRK        |
 112                YANU_ACTION_RFE         |
 113                YANU_ACTION_RPE         |
 114            YANU_ACTION_RFE | YANU_ACTION_RFIFO_CLEAR | YANU_ACTION_TFIFO_CLEAR;
 115
 116        writel(action, &uart->action);
 117
 118        /*
 119         * control register cleanup
 120         * no interrupts enabled
 121         * one stop bit
 122         * hardware flow control disabled
 123         * 8 bits
 124         */
 125        control = (0x7 << YANU_CONTROL_BITS_POS);
 126        /* enven parity just to be clean */
 127        control |= YANU_CONTROL_PAREVEN;
 128        /* we set threshold for fifo */
 129        control |= YANU_CONTROL_RDYDLY * YANU_RXFIFO_DLY;
 130        control |= YANU_CONTROL_TXTHR *  YANU_TXFIFO_THR;
 131
 132        writel(control, &uart->control);
 133
 134        /* to set baud rate */
 135        serial_setbrg();
 136
 137        return (0);
 138}
 139
 140
 141/*-----------------------------------------------------------------------
 142 * YANU CONSOLE
 143 *---------------------------------------------------------------------*/
 144void serial_putc (char c)
 145{
 146        int tx_chars;
 147        unsigned status;
 148
 149        if (c == '\n')
 150                serial_putc ('\r');
 151
 152        while (1) {
 153                status = readl(&uart->status);
 154                tx_chars = (status>>YANU_TFIFO_CHARS_POS)
 155                        & ((1<<YANU_TFIFO_CHARS_N)-1);
 156                if (tx_chars < YANU_TXFIFO_SIZE-1)
 157                        break;
 158                WATCHDOG_RESET ();
 159        }
 160
 161        writel((unsigned char)c, &uart->data);
 162}
 163
 164void serial_puts (const char *s)
 165{
 166        while (*s != 0) {
 167                serial_putc (*s++);
 168        }
 169}
 170
 171
 172int serial_tstc(void)
 173{
 174        unsigned status ;
 175
 176        status = readl(&uart->status);
 177        return (((status >> YANU_RFIFO_CHARS_POS) &
 178                 ((1 << YANU_RFIFO_CHARS_N) - 1)) > 0);
 179}
 180
 181int serial_getc (void)
 182{
 183        while (serial_tstc() == 0)
 184                WATCHDOG_RESET ();
 185
 186        /* first we pull the char */
 187        writel(YANU_ACTION_RFIFO_PULL, &uart->action);
 188
 189        return(readl(&uart->data) & YANU_DATA_CHAR_MASK);
 190}
 191