158 lines
3.3 KiB
C
158 lines
3.3 KiB
C
/*
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* Copyright 2010, Renato Andreola <renato.andreola@imagos.it>
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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#include <common.h>
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#include <watchdog.h>
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#include <asm/io.h>
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#include <nios2-yanu.h>
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#include <serial.h>
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DECLARE_GLOBAL_DATA_PTR;
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/*-----------------------------------------------------------------*/
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/* YANU Imagos serial port */
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/*-----------------------------------------------------------------*/
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static yanu_uart_t *uart = (yanu_uart_t *)CONFIG_SYS_NIOS_CONSOLE;
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static void oc_serial_setbrg(void)
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{
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int n, k;
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const unsigned max_uns = 0xFFFFFFFF;
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unsigned best_n, best_m, baud;
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unsigned baudrate;
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#if defined(CONFIG_SYS_NIOS_FIXEDBAUD)
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/* Everything's already setup for fixed-baud PTF assignment */
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baudrate = CONFIG_BAUDRATE;
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#else
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baudrate = gd->baudrate;
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#endif
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/* compute best N and M couple */
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best_n = YANU_MAX_PRESCALER_N;
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for (n = YANU_MAX_PRESCALER_N; n >= 0; n--) {
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if ((unsigned)CONFIG_SYS_CLK_FREQ / (1 << (n + 4)) >=
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baudrate) {
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best_n = n;
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break;
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}
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}
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for (k = 0;; k++) {
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if (baudrate <= (max_uns >> (15+n-k)))
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break;
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}
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best_m =
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(baudrate * (1 << (15 + n - k))) /
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((unsigned)CONFIG_SYS_CLK_FREQ >> k);
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baud = best_m + best_n * YANU_BAUDE;
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writel(baud, &uart->baud);
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return;
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}
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static int oc_serial_init(void)
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{
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unsigned action,control;
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/* status register cleanup */
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action = YANU_ACTION_RRRDY |
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YANU_ACTION_RTRDY |
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YANU_ACTION_ROE |
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YANU_ACTION_RBRK |
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YANU_ACTION_RFE |
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YANU_ACTION_RPE |
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YANU_ACTION_RFE | YANU_ACTION_RFIFO_CLEAR | YANU_ACTION_TFIFO_CLEAR;
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writel(action, &uart->action);
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/*
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* control register cleanup
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* no interrupts enabled
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* one stop bit
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* hardware flow control disabled
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* 8 bits
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*/
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control = (0x7 << YANU_CONTROL_BITS_POS);
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/* enven parity just to be clean */
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control |= YANU_CONTROL_PAREVEN;
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/* we set threshold for fifo */
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control |= YANU_CONTROL_RDYDLY * YANU_RXFIFO_DLY;
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control |= YANU_CONTROL_TXTHR * YANU_TXFIFO_THR;
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writel(control, &uart->control);
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/* to set baud rate */
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serial_setbrg();
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return (0);
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}
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/*-----------------------------------------------------------------------
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* YANU CONSOLE
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*---------------------------------------------------------------------*/
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static void oc_serial_putc(char c)
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{
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int tx_chars;
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unsigned status;
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if (c == '\n')
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serial_putc ('\r');
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while (1) {
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status = readl(&uart->status);
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tx_chars = (status>>YANU_TFIFO_CHARS_POS)
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& ((1<<YANU_TFIFO_CHARS_N)-1);
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if (tx_chars < YANU_TXFIFO_SIZE-1)
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break;
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WATCHDOG_RESET ();
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}
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writel((unsigned char)c, &uart->data);
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}
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static int oc_serial_tstc(void)
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{
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unsigned status ;
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status = readl(&uart->status);
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return (((status >> YANU_RFIFO_CHARS_POS) &
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((1 << YANU_RFIFO_CHARS_N) - 1)) > 0);
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}
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static int oc_serial_getc(void)
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{
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while (serial_tstc() == 0)
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WATCHDOG_RESET ();
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/* first we pull the char */
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writel(YANU_ACTION_RFIFO_PULL, &uart->action);
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return(readl(&uart->data) & YANU_DATA_CHAR_MASK);
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}
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static struct serial_device oc_serial_drv = {
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.name = "oc_serial",
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.start = oc_serial_init,
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.stop = NULL,
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.setbrg = oc_serial_setbrg,
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.putc = oc_serial_putc,
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.puts = default_serial_puts,
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.getc = oc_serial_getc,
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.tstc = oc_serial_tstc,
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};
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void oc_serial_initialize(void)
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{
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serial_register(&oc_serial_drv);
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}
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__weak struct serial_device *default_serial_console(void)
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{
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return &oc_serial_drv;
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}
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