1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * (C) Copyright 2008 - 2013 Tensilica Inc.
4  */
5 
6 #include <common.h>
7 #include <time.h>
8 #include <asm/global_data.h>
9 #include <linux/delay.h>
10 #include <linux/stringify.h>
11 
12 DECLARE_GLOBAL_DATA_PTR;
13 
14 #if XCHAL_HAVE_CCOUNT
get_ccount(void)15 static ulong get_ccount(void)
16 {
17 	ulong ccount;
18 	asm volatile ("rsr %0,"__stringify(CCOUNT) : "=a" (ccount));
19 	return ccount;
20 }
21 #else
22 static ulong fake_ccount;
23 #define get_ccount() fake_ccount
24 #endif
25 
delay_cycles(unsigned cycles)26 static void delay_cycles(unsigned cycles)
27 {
28 #if XCHAL_HAVE_CCOUNT
29 	unsigned expiry = get_ccount() + cycles;
30 	while ((signed)(expiry - get_ccount()) > 0)
31 		;
32 #else
33 #warning "Without Xtensa timer option, timing will not be accurate."
34 
35 	/*
36 	 * Approximate the cycle count by a loop iteration count.
37 	 * This is highly dependent on config and optimization.
38 	 */
39 
40 	volatile unsigned i;
41 	for (i = cycles >> 4U; i > 0; --i)
42 		;
43 	fake_ccount += cycles;
44 #endif
45 }
46 
47 /*
48  * Delay (busy-wait) for a number of microseconds.
49  */
50 
__udelay(unsigned long usec)51 void __udelay(unsigned long usec)
52 {
53 	ulong lo, hi, i;
54 	ulong mhz = CONFIG_SYS_CLK_FREQ / 1000000;
55 
56 	/* Scale to support full 32-bit usec range */
57 
58 	lo = usec & ((1<<22)-1);
59 	hi = usec >> 22UL;
60 	for (i = 0; i < hi; ++i)
61 		delay_cycles(mhz << 22);
62 	delay_cycles(mhz * lo);
63 }
64 
65 
66 /*
67  * Return the elapsed time (ticks) since 'base'.
68  */
69 
get_timer(ulong base)70 ulong get_timer(ulong base)
71 {
72 	/* Don't tie up a timer; use cycle counter if available (or fake it) */
73 
74 #if XCHAL_HAVE_CCOUNT
75 	register ulong ccount;
76 	__asm__ volatile ("rsr %0, CCOUNT" : "=a"(ccount));
77 	return ccount / (CONFIG_SYS_CLK_FREQ / CONFIG_SYS_HZ) - base;
78 #else
79 	/*
80 	 * Add at least the overhead of this call (in cycles).
81 	 * Avoids hanging in case caller doesn't use udelay().
82 	 * Note that functions that don't call udelay() (such as
83 	 * the "sleep" command) will not get a significant delay
84 	 * because there is no time reference.
85 	 */
86 
87 	fake_ccount += 20;
88 	return fake_ccount / (CONFIG_SYS_CLK_FREQ / CONFIG_SYS_HZ) - base;
89 #endif
90 }
91 
92 
93 /*
94  * This function is derived from ARM/PowerPC code (read timebase as long long).
95  * On Xtensa it just returns the timer value.
96  */
get_ticks(void)97 unsigned long long get_ticks(void)
98 {
99 	return get_timer(0);
100 }
101 
102 /*
103  * This function is derived from ARM/PowerPC code (timebase clock frequency).
104  * On Xtensa it returns the number of timer ticks per second.
105  */
get_tbclk(void)106 ulong get_tbclk(void)
107 {
108 	return CONFIG_SYS_HZ;
109 }
110 
111 #if XCHAL_HAVE_CCOUNT
timer_get_us(void)112 unsigned long timer_get_us(void)
113 {
114 	unsigned long ccount;
115 
116 	__asm__ volatile ("rsr %0, CCOUNT" : "=a"(ccount));
117 	return ccount / (CONFIG_SYS_CLK_FREQ / 1000000);
118 }
119 #endif
120