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