1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * (C) Copyright 2008 - 2013 Tensilica Inc.
4 */
5
6#include <common.h>
7#include <clock_legacy.h>
8#include <time.h>
9#include <asm/global_data.h>
10#include <linux/delay.h>
11#include <linux/stringify.h>
12
13DECLARE_GLOBAL_DATA_PTR;
14
15#if XCHAL_HAVE_CCOUNT
16static ulong get_ccount(void)
17{
18	ulong ccount;
19	asm volatile ("rsr %0,"__stringify(CCOUNT) : "=a" (ccount));
20	return ccount;
21}
22#else
23static ulong fake_ccount;
24#define get_ccount() fake_ccount
25#endif
26
27static void delay_cycles(unsigned cycles)
28{
29#if XCHAL_HAVE_CCOUNT
30	unsigned expiry = get_ccount() + cycles;
31	while ((signed)(expiry - get_ccount()) > 0)
32		;
33#else
34#warning "Without Xtensa timer option, timing will not be accurate."
35
36	/*
37	 * Approximate the cycle count by a loop iteration count.
38	 * This is highly dependent on config and optimization.
39	 */
40
41	volatile unsigned i;
42	for (i = cycles >> 4U; i > 0; --i)
43		;
44	fake_ccount += cycles;
45#endif
46}
47
48/*
49 * Delay (busy-wait) for a number of microseconds.
50 */
51
52void __udelay(unsigned long usec)
53{
54	ulong lo, hi, i;
55	ulong mhz = get_board_sys_clk() / 1000000;
56
57	/* Scale to support full 32-bit usec range */
58
59	lo = usec & ((1<<22)-1);
60	hi = usec >> 22UL;
61	for (i = 0; i < hi; ++i)
62		delay_cycles(mhz << 22);
63	delay_cycles(mhz * lo);
64}
65
66
67/*
68 * Return the elapsed time (ticks) since 'base'.
69 */
70
71ulong get_timer(ulong base)
72{
73	/* Don't tie up a timer; use cycle counter if available (or fake it) */
74
75#if XCHAL_HAVE_CCOUNT
76	register ulong ccount;
77	__asm__ volatile ("rsr %0, CCOUNT" : "=a"(ccount));
78	return ccount / (get_board_sys_clk() / CONFIG_SYS_HZ) - base;
79#else
80	/*
81	 * Add at least the overhead of this call (in cycles).
82	 * Avoids hanging in case caller doesn't use udelay().
83	 * Note that functions that don't call udelay() (such as
84	 * the "sleep" command) will not get a significant delay
85	 * because there is no time reference.
86	 */
87
88	fake_ccount += 20;
89	return fake_ccount / (get_board_sys_clk() / CONFIG_SYS_HZ) - base;
90#endif
91}
92
93
94/*
95 * This function is derived from ARM/PowerPC code (read timebase as long long).
96 * On Xtensa it just returns the timer value.
97 */
98unsigned long long get_ticks(void)
99{
100	return get_timer(0);
101}
102
103/*
104 * This function is derived from ARM/PowerPC code (timebase clock frequency).
105 * On Xtensa it returns the number of timer ticks per second.
106 */
107ulong get_tbclk(void)
108{
109	return CONFIG_SYS_HZ;
110}
111
112#if XCHAL_HAVE_CCOUNT
113unsigned long timer_get_us(void)
114{
115	unsigned long ccount;
116
117	__asm__ volatile ("rsr %0, CCOUNT" : "=a"(ccount));
118	return ccount / (get_board_sys_clk() / 1000000);
119}
120#endif
121