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Tom Rini83d290c2018-05-06 17:58:06 -04001// SPDX-License-Identifier: GPL-2.0+
Chris Zankelc978b522016-08-10 18:36:44 +03002/*
3 * (C) Copyright 2008 - 2013 Tensilica Inc.
Chris Zankelc978b522016-08-10 18:36:44 +03004 */
5
6#include <common.h>
7#include <asm/global_data.h>
8#include <linux/stringify.h>
9
10DECLARE_GLOBAL_DATA_PTR;
11
12#if XCHAL_HAVE_CCOUNT
13static ulong get_ccount(void)
14{
15 ulong ccount;
16 asm volatile ("rsr %0,"__stringify(CCOUNT) : "=a" (ccount));
17 return ccount;
18}
19#else
20static ulong fake_ccount;
21#define get_ccount() fake_ccount
22#endif
23
24static void delay_cycles(unsigned cycles)
25{
26#if XCHAL_HAVE_CCOUNT
27 unsigned expiry = get_ccount() + cycles;
28 while ((signed)(expiry - get_ccount()) > 0)
29 ;
30#else
31#warning "Without Xtensa timer option, timing will not be accurate."
32
33 /*
34 * Approximate the cycle count by a loop iteration count.
35 * This is highly dependent on config and optimization.
36 */
37
38 volatile unsigned i;
39 for (i = cycles >> 4U; i > 0; --i)
40 ;
41 fake_ccount += cycles;
42#endif
43}
44
45/*
46 * Delay (busy-wait) for a number of microseconds.
47 */
48
49void __udelay(unsigned long usec)
50{
51 ulong lo, hi, i;
52 ulong mhz = CONFIG_SYS_CLK_FREQ / 1000000;
53
54 /* Scale to support full 32-bit usec range */
55
56 lo = usec & ((1<<22)-1);
57 hi = usec >> 22UL;
58 for (i = 0; i < hi; ++i)
59 delay_cycles(mhz << 22);
60 delay_cycles(mhz * lo);
61}
62
63
64/*
65 * Return the elapsed time (ticks) since 'base'.
66 */
67
68ulong get_timer(ulong base)
69{
70 /* Don't tie up a timer; use cycle counter if available (or fake it) */
71
72#if XCHAL_HAVE_CCOUNT
73 register ulong ccount;
74 __asm__ volatile ("rsr %0, CCOUNT" : "=a"(ccount));
75 return ccount / (CONFIG_SYS_CLK_FREQ / CONFIG_SYS_HZ) - base;
76#else
77 /*
78 * Add at least the overhead of this call (in cycles).
79 * Avoids hanging in case caller doesn't use udelay().
80 * Note that functions that don't call udelay() (such as
81 * the "sleep" command) will not get a significant delay
82 * because there is no time reference.
83 */
84
85 fake_ccount += 20;
86 return fake_ccount / (CONFIG_SYS_CLK_FREQ / CONFIG_SYS_HZ) - base;
87#endif
88}
89
90
91/*
92 * This function is derived from ARM/PowerPC code (read timebase as long long).
93 * On Xtensa it just returns the timer value.
94 */
95unsigned long long get_ticks(void)
96{
97 return get_timer(0);
98}
99
100/*
101 * This function is derived from ARM/PowerPC code (timebase clock frequency).
102 * On Xtensa it returns the number of timer ticks per second.
103 */
104ulong get_tbclk(void)
105{
Masahiro Yamada63a75782016-09-06 22:17:38 +0900106 return CONFIG_SYS_HZ;
Chris Zankelc978b522016-08-10 18:36:44 +0300107}
108
109#if XCHAL_HAVE_CCOUNT
110unsigned long timer_get_us(void)
111{
112 unsigned long ccount;
113
114 __asm__ volatile ("rsr %0, CCOUNT" : "=a"(ccount));
115 return ccount / (CONFIG_SYS_CLK_FREQ / 1000000);
116}
117#endif