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79 lines
2.1 KiB
79 lines
2.1 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef _LINUX_DELAY_H |
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#define _LINUX_DELAY_H |
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/* |
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* Copyright (C) 1993 Linus Torvalds |
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* |
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* Delay routines, using a pre-computed "loops_per_jiffy" value. |
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* |
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* Please note that ndelay(), udelay() and mdelay() may return early for |
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* several reasons: |
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* 1. computed loops_per_jiffy too low (due to the time taken to |
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* execute the timer interrupt.) |
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* 2. cache behaviour affecting the time it takes to execute the |
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* loop function. |
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* 3. CPU clock rate changes. |
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* |
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* Please see this thread: |
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* https://lists.openwall.net/linux-kernel/2011/01/09/56 |
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*/ |
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#include <linux/kernel.h> |
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extern unsigned long loops_per_jiffy; |
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#include <asm/delay.h> |
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/* |
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* Using udelay() for intervals greater than a few milliseconds can |
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* risk overflow for high loops_per_jiffy (high bogomips) machines. The |
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* mdelay() provides a wrapper to prevent this. For delays greater |
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* than MAX_UDELAY_MS milliseconds, the wrapper is used. Architecture |
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* specific values can be defined in asm-???/delay.h as an override. |
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* The 2nd mdelay() definition ensures GCC will optimize away the |
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* while loop for the common cases where n <= MAX_UDELAY_MS -- Paul G. |
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*/ |
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#ifndef MAX_UDELAY_MS |
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#define MAX_UDELAY_MS 5 |
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#endif |
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#ifndef mdelay |
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#define mdelay(n) (\ |
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(__builtin_constant_p(n) && (n)<=MAX_UDELAY_MS) ? udelay((n)*1000) : \ |
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({unsigned long __ms=(n); while (__ms--) udelay(1000);})) |
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#endif |
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#ifndef ndelay |
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static inline void ndelay(unsigned long x) |
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{ |
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udelay(DIV_ROUND_UP(x, 1000)); |
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} |
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#define ndelay(x) ndelay(x) |
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#endif |
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extern unsigned long lpj_fine; |
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void calibrate_delay(void); |
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void __attribute__((weak)) calibration_delay_done(void); |
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void msleep(unsigned int msecs); |
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unsigned long msleep_interruptible(unsigned int msecs); |
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void usleep_range(unsigned long min, unsigned long max); |
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static inline void ssleep(unsigned int seconds) |
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{ |
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msleep(seconds * 1000); |
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} |
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/* see Documentation/timers/timers-howto.rst for the thresholds */ |
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static inline void fsleep(unsigned long usecs) |
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{ |
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if (usecs <= 10) |
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udelay(usecs); |
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else if (usecs <= 20000) |
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usleep_range(usecs, 2 * usecs); |
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else |
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msleep(DIV_ROUND_UP(usecs, 1000)); |
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} |
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#endif /* defined(_LINUX_DELAY_H) */
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