1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * (C) Copyright 2008
4 * Texas Instruments
5 *
6 * Richard Woodruff <r-woodruff2@ti.com>
7 * Syed Moahmmed Khasim <khasim@ti.com>
8 *
9 * (C) Copyright 2002
10 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
11 * Marius Groeger <mgroeger@sysgo.de>
12 * Alex Zuepke <azu@sysgo.de>
13 *
14 * (C) Copyright 2002
15 * Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
16 */
17
18#include <config.h>
19#include <init.h>
20#include <time.h>
21#include <asm/global_data.h>
22#include <asm/io.h>
23#include <asm/arch/cpu.h>
24#include <asm/arch/clock.h>
25#include <asm/omap_common.h>
26#include <linux/delay.h>
27
28DECLARE_GLOBAL_DATA_PTR;
29
30static struct gptimer *timer_base = (struct gptimer *)CFG_SYS_TIMERBASE;
31static ulong get_timer_masked(void);
32
33/*
34 * Nothing really to do with interrupts, just starts up a counter.
35 */
36
37#define TIMER_CLOCK		(V_SCLK / (2 << SYS_PTV))
38#define TIMER_OVERFLOW_VAL	0xffffffff
39#define TIMER_LOAD_VAL		0
40
41int timer_init(void)
42{
43	/* start the counter ticking up, reload value on overflow */
44	writel(TIMER_LOAD_VAL, &timer_base->tldr);
45	/* enable timer */
46	writel((SYS_PTV << 2) | TCLR_PRE | TCLR_AR | TCLR_ST,
47		&timer_base->tclr);
48
49	return 0;
50}
51
52/*
53 * timer without interrupts
54 */
55ulong get_timer(ulong base)
56{
57	return get_timer_masked() - base;
58}
59
60/* delay x useconds */
61void __udelay(unsigned long usec)
62{
63	long tmo = usec * (TIMER_CLOCK / 1000) / 1000;
64	unsigned long now, last = readl(&timer_base->tcrr);
65
66	while (tmo > 0) {
67		now = readl(&timer_base->tcrr);
68		if (last > now) /* count up timer overflow */
69			tmo -= TIMER_OVERFLOW_VAL - last + now + 1;
70		else
71			tmo -= now - last;
72		last = now;
73	}
74}
75
76static ulong get_timer_masked(void)
77{
78	/* current tick value */
79	ulong now = readl(&timer_base->tcrr) / (TIMER_CLOCK / CONFIG_SYS_HZ);
80
81	if (now >= gd->arch.lastinc) {	/* normal mode (non roll) */
82		/* move stamp fordward with absoulte diff ticks */
83		gd->arch.tbl += (now - gd->arch.lastinc);
84	} else {	/* we have rollover of incrementer */
85		gd->arch.tbl += ((TIMER_OVERFLOW_VAL / (TIMER_CLOCK /
86				CONFIG_SYS_HZ)) - gd->arch.lastinc) + now;
87	}
88	gd->arch.lastinc = now;
89	return gd->arch.tbl;
90}
91
92/*
93 * This function is derived from PowerPC code (read timebase as long long).
94 * On ARM it just returns the timer value.
95 */
96unsigned long long get_ticks(void)
97{
98	return get_timer(0);
99}
100
101/*
102 * This function is derived from PowerPC code (timebase clock frequency).
103 * On ARM it returns the number of timer ticks per second.
104 */
105ulong get_tbclk(void)
106{
107	return CONFIG_SYS_HZ;
108}
109