xref: /openbmc/u-boot/arch/arm/mach-omap2/timer.c (revision 730d2544)
1 /*
2  * (C) Copyright 2008
3  * Texas Instruments
4  *
5  * Richard Woodruff <r-woodruff2@ti.com>
6  * Syed Moahmmed Khasim <khasim@ti.com>
7  *
8  * (C) Copyright 2002
9  * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
10  * Marius Groeger <mgroeger@sysgo.de>
11  * Alex Zuepke <azu@sysgo.de>
12  *
13  * (C) Copyright 2002
14  * Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
15  *
16  * SPDX-License-Identifier:	GPL-2.0+
17  */
18 
19 #include <common.h>
20 #include <asm/io.h>
21 #include <asm/arch/cpu.h>
22 #include <asm/arch/clock.h>
23 
24 DECLARE_GLOBAL_DATA_PTR;
25 
26 static struct gptimer *timer_base = (struct gptimer *)CONFIG_SYS_TIMERBASE;
27 
28 /*
29  * Nothing really to do with interrupts, just starts up a counter.
30  */
31 
32 #define TIMER_CLOCK		(V_SCLK / (2 << CONFIG_SYS_PTV))
33 #define TIMER_OVERFLOW_VAL	0xffffffff
34 #define TIMER_LOAD_VAL		0
35 
36 int timer_init(void)
37 {
38 	/* start the counter ticking up, reload value on overflow */
39 	writel(TIMER_LOAD_VAL, &timer_base->tldr);
40 	/* enable timer */
41 	writel((CONFIG_SYS_PTV << 2) | TCLR_PRE | TCLR_AR | TCLR_ST,
42 		&timer_base->tclr);
43 
44 	return 0;
45 }
46 
47 /*
48  * timer without interrupts
49  */
50 ulong get_timer(ulong base)
51 {
52 	return get_timer_masked() - base;
53 }
54 
55 /* delay x useconds */
56 void __udelay(unsigned long usec)
57 {
58 	long tmo = usec * (TIMER_CLOCK / 1000) / 1000;
59 	unsigned long now, last = readl(&timer_base->tcrr);
60 
61 	while (tmo > 0) {
62 		now = readl(&timer_base->tcrr);
63 		if (last > now) /* count up timer overflow */
64 			tmo -= TIMER_OVERFLOW_VAL - last + now + 1;
65 		else
66 			tmo -= now - last;
67 		last = now;
68 	}
69 }
70 
71 ulong get_timer_masked(void)
72 {
73 	/* current tick value */
74 	ulong now = readl(&timer_base->tcrr) / (TIMER_CLOCK / CONFIG_SYS_HZ);
75 
76 	if (now >= gd->arch.lastinc) {	/* normal mode (non roll) */
77 		/* move stamp fordward with absoulte diff ticks */
78 		gd->arch.tbl += (now - gd->arch.lastinc);
79 	} else {	/* we have rollover of incrementer */
80 		gd->arch.tbl += ((TIMER_OVERFLOW_VAL / (TIMER_CLOCK /
81 				CONFIG_SYS_HZ)) - gd->arch.lastinc) + now;
82 	}
83 	gd->arch.lastinc = now;
84 	return gd->arch.tbl;
85 }
86 
87 /*
88  * This function is derived from PowerPC code (read timebase as long long).
89  * On ARM it just returns the timer value.
90  */
91 unsigned long long get_ticks(void)
92 {
93 	return get_timer(0);
94 }
95 
96 /*
97  * This function is derived from PowerPC code (timebase clock frequency).
98  * On ARM it returns the number of timer ticks per second.
99  */
100 ulong get_tbclk(void)
101 {
102 	return CONFIG_SYS_HZ;
103 }
104