1 // SPDX-License-Identifier: GPL-2.0-only
3 * Delay loops based on the OpenRISC implementation.
5 * Copyright (C) 2012 ARM Limited
7 * Author: Will Deacon <will.deacon@arm.com>
10 #include <linux/delay.h>
11 #include <linux/init.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/timex.h>
16 #include <clocksource/arm_arch_timer.h>
18 #define USECS_TO_CYCLES(time_usecs) \
19 xloops_to_cycles((time_usecs) * 0x10C7UL)
21 static inline unsigned long xloops_to_cycles(unsigned long xloops
)
23 return (xloops
* loops_per_jiffy
* HZ
) >> 32;
26 void __delay(unsigned long cycles
)
28 cycles_t start
= get_cycles();
30 if (alternative_has_cap_unlikely(ARM64_HAS_WFXT
)) {
31 u64 end
= start
+ cycles
;
34 * Start with WFIT. If an interrupt makes us resume
35 * early, use a WFET loop to complete the delay.
38 while ((get_cycles() - start
) < cycles
)
40 } else if (arch_timer_evtstrm_available()) {
41 const cycles_t timer_evt_period
=
42 USECS_TO_CYCLES(ARCH_TIMER_EVT_STREAM_PERIOD_US
);
44 while ((get_cycles() - start
+ timer_evt_period
) < cycles
)
48 while ((get_cycles() - start
) < cycles
)
51 EXPORT_SYMBOL(__delay
);
53 inline void __const_udelay(unsigned long xloops
)
55 __delay(xloops_to_cycles(xloops
));
57 EXPORT_SYMBOL(__const_udelay
);
59 void __udelay(unsigned long usecs
)
61 __const_udelay(usecs
* 0x10C7UL
); /* 2**32 / 1000000 (rounded up) */
63 EXPORT_SYMBOL(__udelay
);
65 void __ndelay(unsigned long nsecs
)
67 __const_udelay(nsecs
* 0x5UL
); /* 2**32 / 1000000000 (rounded up) */
69 EXPORT_SYMBOL(__ndelay
);