common.c revision 1.3 
1/* $Id: common.c,v 1.3 2013/02/23 16:22:39 jkunz Exp $ */
2
3/*
4 * Copyright (c) 2012 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Petri Laakso.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#include <sys/param.h>
33#include <sys/types.h>
34#include <sys/cdefs.h>
35
36#include <arm/imx/imx23_digctlreg.h>
37#include <arm/imx/imx23_uartdbgreg.h>
38
39#include "common.h"
40
41/*
42 * Delay us microseconds.
43 */
44void
45delay(unsigned int us)
46{
47	uint32_t start;
48	uint32_t now;
49	uint32_t elapsed;
50	uint32_t total;
51	uint32_t last;
52
53	total = 0;
54	last = 0;
55	start = REG_RD(HW_DIGCTL_BASE + HW_DIGCTL_MICROSECONDS);
56
57	do {
58		now = REG_RD(HW_DIGCTL_BASE + HW_DIGCTL_MICROSECONDS);
59
60		if (start <= now)
61			elapsed = now - start;
62		else	/* Take care of overflow. */
63			elapsed = (UINT32_MAX - start) + 1 + now;
64
65		total += elapsed - last;
66		last = elapsed;
67
68	} while (total < us);
69
70	return;
71}
72
73/*
74 * Write character to debug UART.
75 */
76void
77putchar(int ch)
78{
79
80	/* Wait until transmit FIFO has space for the new character. */
81	while (REG_RD_HW(HW_UARTDBG_BASE + HW_UARTDBGFR) & HW_UARTDBGFR_TXFF);
82
83	REG_WR_BYTE(HW_UARTDBG_BASE + HW_UARTDBGDR,
84	    __SHIFTIN(ch, HW_UARTDBGDR_DATA));
85#ifdef DEBUG
86	/* Flush: Wait until transmit FIFO contents are written to UART. */
87	while (!(REG_RD_HW(HW_UARTDBG_BASE + HW_UARTDBGFR) &
88	    HW_UARTDBGFR_TXFE));
89#endif
90
91	return;
92}
93
94/*
95 * Read character from debug UART.
96 */
97int
98getchar(void)
99{
100
101	/* Wait until receive FIFO has character(s) */
102
103	while (REG_RD_HW(HW_UARTDBG_BASE + HW_UARTDBGFR) & HW_UARTDBGFR_RXFE);
104
105	return REG_RD_HW(HW_UARTDBG_BASE + HW_UARTDBGDR) & 0xFF;
106}
107