summaryrefslogtreecommitdiffstats
path: root/drivers/serial/opencores_yanu.c
blob: d4ed60c303037b09f3f976d6f51f5130ddc5b5dc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
/*
 * 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;
}
OpenPOWER on IntegriCloud