xref: /openbmc/u-boot/arch/powerpc/lib/time.c (revision 85ab0452)
1 /*
2  * (C) Copyright 2000, 2001
3  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4  *
5  * SPDX-License-Identifier:	GPL-2.0+
6  */
7 
8 #include <common.h>
9 #include <asm/io.h>
10 
11 /* ------------------------------------------------------------------------- */
12 
13 /*
14  * This function is intended for SHORT delays only.
15  * It will overflow at around 10 seconds @ 400MHz,
16  * or 20 seconds @ 200MHz.
17  */
18 unsigned long usec2ticks(unsigned long usec)
19 {
20 	ulong ticks;
21 
22 	if (usec < 1000) {
23 		ticks = ((usec * (get_tbclk()/1000)) + 500) / 1000;
24 	} else {
25 		ticks = ((usec / 10) * (get_tbclk() / 100000));
26 	}
27 
28 	return (ticks);
29 }
30 
31 /* ------------------------------------------------------------------------- */
32 
33 /*
34  * We implement the delay by converting the delay (the number of
35  * microseconds to wait) into a number of time base ticks; then we
36  * watch the time base until it has incremented by that amount.
37  */
38 void __udelay(unsigned long usec)
39 {
40 	ulong ticks = usec2ticks (usec);
41 	wait_ticks (ticks);
42 }
43 
44 /* ------------------------------------------------------------------------- */
45 #ifndef CONFIG_NAND_SPL
46 unsigned long ticks2usec(unsigned long ticks)
47 {
48 	ulong tbclk = get_tbclk();
49 
50 	/* usec = ticks * 1000000 / tbclk
51 	 * Multiplication would overflow at ~4.2e3 ticks,
52 	 * so we break it up into
53 	 * usec = ( ( ticks * 1000) / tbclk ) * 1000;
54 	 */
55 	ticks *= 1000L;
56 	ticks /= tbclk;
57 	ticks *= 1000L;
58 
59 	return ((ulong)ticks);
60 }
61 #endif
62 /* ------------------------------------------------------------------------- */
63 
64 int timer_init(void)
65 {
66 	unsigned long temp;
67 
68 	/* reset */
69 	asm volatile("li %0,0 ; mttbl %0 ; mttbu %0;"
70 	     : "=&r"(temp) );
71 
72 	return (0);
73 }
74 /* ------------------------------------------------------------------------- */
75