summaryrefslogtreecommitdiffstats
path: root/arch/arm/cpu/arm926ejs/mx25/timer.c
blob: 11d41a8bf9f5b44ec098c18e4b62911f66cc1115 (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
183
184
185
186
187
/*
 * (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
 * Gary Jennejohn, DENX Software Engineering, <gj@denx.de>
 *
 * (C) Copyright 2009
 * Ilya Yanok, Emcraft Systems Ltd, <yanok@emcraft.com>
 *
 * (C) Copyright 2009 DENX Software Engineering
 * Author: John Rigby <jrigby@gmail.com>
 * 	Add support for MX25
 *
 * 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 <div64.h>
#include <asm/io.h>
#include <asm/arch/imx-regs.h>

static ulong timestamp;
static ulong lastinc;

/*
 * "time" is measured in 1 / CONFIG_SYS_HZ seconds,
 * "tick" is internal timer period
 */
#ifdef CONFIG_MX25_TIMER_HIGH_PRECISION
/* ~0.4% error - measured with stop-watch on 100s boot-delay */
static inline unsigned long long tick_to_time(unsigned long long tick)
{
	tick *= CONFIG_SYS_HZ;
	do_div(tick, CONFIG_MX25_CLK32);
	return tick;
}

static inline unsigned long long time_to_tick(unsigned long long time)
{
	time *= CONFIG_MX25_CLK32;
	do_div(time, CONFIG_SYS_HZ);
	return time;
}

static inline unsigned long long us_to_tick(unsigned long long us)
{
	us = us * CONFIG_MX25_CLK32 + 999999;
	do_div(us, 1000000);
	return us;
}
#else
/* ~2% error */
#define TICK_PER_TIME	((CONFIG_MX25_CLK32 + CONFIG_SYS_HZ / 2) / \
		CONFIG_SYS_HZ)
#define US_PER_TICK	(1000000 / CONFIG_MX25_CLK32)

static inline unsigned long long tick_to_time(unsigned long long tick)
{
	do_div(tick, TICK_PER_TIME);
	return tick;
}

static inline unsigned long long time_to_tick(unsigned long long time)
{
	return time * TICK_PER_TIME;
}

static inline unsigned long long us_to_tick(unsigned long long us)
{
	us += US_PER_TICK - 1;
	do_div(us, US_PER_TICK);
	return us;
}
#endif

/* nothing really to do with interrupts, just starts up a counter. */
/* The 32KHz 32-bit timer overruns in 134217 seconds */
int timer_init(void)
{
	int i;
	struct gpt_regs *gpt = (struct gpt_regs *)IMX_GPT1_BASE;
	struct ccm_regs *ccm = (struct ccm_regs *)IMX_CCM_BASE;

	/* setup GP Timer 1 */
	writel(GPT_CTRL_SWR, &gpt->ctrl);

	writel(readl(&ccm->cgr1) | CCM_CGR1_GPT1, &ccm->cgr1);

	for (i = 0; i < 100; i++)
		writel(0, &gpt->ctrl); /* We have no udelay by now */
	writel(0, &gpt->pre); /* prescaler = 1 */
	/* Freerun Mode, 32KHz input */
	writel(readl(&gpt->ctrl) | GPT_CTRL_CLKSOURCE_32 | GPT_CTRL_FRR,
			&gpt->ctrl);
	writel(readl(&gpt->ctrl) | GPT_CTRL_TEN, &gpt->ctrl);

	return 0;
}

void reset_timer_masked(void)
{
	struct gpt_regs *gpt = (struct gpt_regs *)IMX_GPT1_BASE;
	/* reset time */
	/* capture current incrementer value time */
	lastinc = readl(&gpt->counter);
	timestamp = 0; /* start "advancing" time stamp from 0 */
}

void reset_timer(void)
{
	reset_timer_masked();
}

unsigned long long get_ticks (void)
{
	struct gpt_regs *gpt = (struct gpt_regs *)IMX_GPT1_BASE;
	ulong now = readl(&gpt->counter); /* current tick value */

	if (now >= lastinc) {
		/*
		 * normal mode (non roll)
		 * move stamp forward with absolut diff ticks
		 */
		timestamp += (now - lastinc);
	} else {
		/* we have rollover of incrementer */
		timestamp += (0xFFFFFFFF - lastinc) + now;
	}
	lastinc = now;
	return timestamp;
}

ulong get_timer_masked (void)
{
	/*
	 * get_ticks() returns a long long (64 bit), it wraps in
	 * 2^64 / CONFIG_MX25_CLK32 = 2^64 / 2^15 = 2^49 ~ 5 * 10^14 (s) ~
	 * 5 * 10^9 days... and get_ticks() * CONFIG_SYS_HZ wraps in
	 * 5 * 10^6 days - long enough.
	 */
	return tick_to_time(get_ticks());
}

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

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

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

	tmo = us_to_tick(usec);
	tmp = get_ticks() + tmo;	/* get current timestamp */

	while (get_ticks() < tmp)	/* loop till event */
		 /*NOP*/;
}
OpenPOWER on IntegriCloud