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 <common.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 
28 DECLARE_GLOBAL_DATA_PTR;
29 
30 static struct gptimer *timer_base = (struct gptimer *)CFG_SYS_TIMERBASE;
31 static 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 
timer_init(void)41 int 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  */
get_timer(ulong base)55 ulong get_timer(ulong base)
56 {
57 	return get_timer_masked() - base;
58 }
59 
60 /* delay x useconds */
__udelay(unsigned long usec)61 void __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 
get_timer_masked(void)76 static 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  */
get_ticks(void)96 unsigned 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  */
get_tbclk(void)105 ulong get_tbclk(void)
106 {
107 	return CONFIG_SYS_HZ;
108 }
109