summaryrefslogtreecommitdiff
path: root/cpu/arm926ejs/nomadik/timer.c
blob: 2870d24ad544975567a565b4f8b305689dd00fee (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
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
/*
 * (C) Copyright 2003
 * Texas Instruments <www.ti.com>
 *
 * (C) Copyright 2002
 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
 * Marius Groeger <mgroeger@sysgo.de>
 *
 * (C) Copyright 2002
 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
 * Alex Zuepke <azu@sysgo.de>
 *
 * (C) Copyright 2002-2004
 * Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
 *
 * (C) Copyright 2004
 * Philippe Robin, ARM Ltd. <philippe.robin@arm.com>
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <common.h>
#include <asm/io.h>

#define TIMER_LOAD_VAL 0xffffffff

/* macro to read the 32 bit timer */
#define READ_TIMER readl(CONFIG_SYS_TIMERBASE + 20)

static ulong timestamp;
static ulong lastdec;

/* nothing really to do with interrupts, just starts up a counter. */
int timer_init(void)
{
	/* Load timer with initial value */
	writel(TIMER_LOAD_VAL, CONFIG_SYS_TIMERBASE + 16);

	/*
	 * Set timer to be enabled, free-running, no interrupts, 256 divider,
	 * 32-bit, wrap-mode
	 */
	writel(0x8a, CONFIG_SYS_TIMERBASE + 24);

	/* init the timestamp and lastdec value */
	reset_timer_masked();

	return 0;
}

/*
 * timer without interrupts
 */
void reset_timer(void)
{
	reset_timer_masked();
}

ulong get_timer(ulong base)
{
	return get_timer_masked() - base;
}

void set_timer(ulong t)
{
	timestamp = t;
}

/* delay x useconds AND perserve advance timstamp value */
void udelay(unsigned long usec)
{
	ulong tmo, tmp;

	if (usec >= 1000) {
		/* if "big" number, spread normalization to seconds */
		tmo = usec / 1000;	/* start to normalize */
		tmo *= CONFIG_SYS_HZ;	/* find number of "ticks" */
		tmo /= 1000;		/* finish normalize. */
	} else {
		/* small number, don't kill it prior to HZ multiply */
		tmo = usec * CONFIG_SYS_HZ;
		tmo /= (1000 * 1000);
	}

	tmp = get_timer(0);		/* get current timestamp */
	if ((tmo + tmp + 1) < tmp)	/* will roll time stamp? */
		reset_timer_masked();	/* reset to 0, set lastdec value */
	else
		tmo += tmp;

	while (get_timer_masked() < tmo)
		/* nothing */ ;
}

void reset_timer_masked(void)
{
	/* reset time */
	lastdec = READ_TIMER;	/* capure current decrementer value time */
	timestamp = 0;		/* start "advancing" time stamp from 0 */
}

ulong get_timer_masked(void)
{
	ulong now = READ_TIMER;		/* current tick value */

	if (lastdec >= now) {		/* normal mode (non roll) */
		/* move stamp fordward */
		timestamp += lastdec - now;
	} else {
		/*
		 * An overflow is expected.
		 * nts = ts + ld + (TLV - now)
		 * ts=old stamp, ld=time that passed before passing through -1
		 * (TLV-now) amount of time after passing though -1
		 * nts = new "advancing time stamp"...it could also roll
		 */
		timestamp += lastdec + TIMER_LOAD_VAL - now;
	}
	lastdec = now;

	return timestamp;
}

/* waits specified delay value and resets timestamp */
void udelay_masked(unsigned long usec)
{
	ulong tmo;

	if (usec >= 1000) {
		/* if "big" number, spread normalization to seconds */
		tmo = usec / 1000;	/* start to normalize */
		tmo *= CONFIG_SYS_HZ;	/* find number of "ticks" */
		tmo /= 1000;		/* finish normalize. */
	} else {
		/* else small number, don't kill it prior to HZ multiply */
		tmo = usec * CONFIG_SYS_HZ;
		tmo /= (1000*1000);
	}

	reset_timer_masked();
	/* set "advancing" timestamp to 0, set lastdec vaule */

	while (get_timer_masked() < tmo)
		/* nothing */ ;
}

/*
 * This function is derived from PowerPC code (read timebase as long long).
 * On ARM it just returns the timer value.
 */
unsigned long long get_ticks(void)
{
	return get_timer(0);
}

/*
 * This function is derived from PowerPC code (timebase clock frequency).
 * On ARM it returns the number of timer ticks per second.
 */
ulong get_tbclk(void)
{
	ulong tbclk;

	tbclk = CONFIG_SYS_HZ;
	return tbclk;
}