Line data    Source code

       1             : /* SPDX-License-Identifier: GPL-2.0 */
       2             : #ifndef _LINUX_DELAY_H
       3             : #define _LINUX_DELAY_H
       4             : 
       5             : /*
       6             :  * Copyright (C) 1993 Linus Torvalds
       7             :  *
       8             :  * Delay routines, using a pre-computed "loops_per_jiffy" value.
       9             :  *
      10             :  * Please note that ndelay(), udelay() and mdelay() may return early for
      11             :  * several reasons:
      12             :  *  1. computed loops_per_jiffy too low (due to the time taken to
      13             :  *     execute the timer interrupt.)
      14             :  *  2. cache behaviour affecting the time it takes to execute the
      15             :  *     loop function.
      16             :  *  3. CPU clock rate changes.
      17             :  *
      18             :  * Please see this thread:
      19             :  *   https://lists.openwall.net/linux-kernel/2011/01/09/56
      20             :  */
      21             : 
      22             : #include <linux/math.h>
      23             : #include <linux/sched.h>
      24             : 
      25             : extern unsigned long loops_per_jiffy;
      26             : 
      27             : #include <asm/delay.h>
      28             : 
      29             : /*
      30             :  * Using udelay() for intervals greater than a few milliseconds can
      31             :  * risk overflow for high loops_per_jiffy (high bogomips) machines. The
      32             :  * mdelay() provides a wrapper to prevent this.  For delays greater
      33             :  * than MAX_UDELAY_MS milliseconds, the wrapper is used.  Architecture
      34             :  * specific values can be defined in asm-???/delay.h as an override.
      35             :  * The 2nd mdelay() definition ensures GCC will optimize away the 
      36             :  * while loop for the common cases where n <= MAX_UDELAY_MS  --  Paul G.
      37             :  */
      38             : 
      39             : #ifndef MAX_UDELAY_MS
      40             : #define MAX_UDELAY_MS   5
      41             : #endif
      42             : 
      43             : #ifndef mdelay
      44             : #define mdelay(n) (\
      45             :         (__builtin_constant_p(n) && (n)<=MAX_UDELAY_MS) ? udelay((n)*1000) : \
      46             :         ({unsigned long __ms=(n); while (__ms--) udelay(1000);}))
      47             : #endif
      48             : 
      49             : #ifndef ndelay
      50             : static inline void ndelay(unsigned long x)
      51             : {
      52             :         udelay(DIV_ROUND_UP(x, 1000));
      53             : }
      54             : #define ndelay(x) ndelay(x)
      55             : #endif
      56             : 
      57             : extern unsigned long lpj_fine;
      58             : void calibrate_delay(void);
      59             : unsigned long calibrate_delay_is_known(void);
      60             : void __attribute__((weak)) calibration_delay_done(void);
      61             : void msleep(unsigned int msecs);
      62             : unsigned long msleep_interruptible(unsigned int msecs);
      63             : void usleep_range_state(unsigned long min, unsigned long max,
      64             :                         unsigned int state);
      65             : 
      66             : static inline void usleep_range(unsigned long min, unsigned long max)
      67             : {
      68           0 :         usleep_range_state(min, max, TASK_UNINTERRUPTIBLE);
      69             : }
      70             : 
      71             : static inline void usleep_idle_range(unsigned long min, unsigned long max)
      72             : {
      73             :         usleep_range_state(min, max, TASK_IDLE);
      74             : }
      75             : 
      76             : static inline void ssleep(unsigned int seconds)
      77             : {
      78           0 :         msleep(seconds * 1000);
      79             : }
      80             : 
      81             : /* see Documentation/timers/timers-howto.rst for the thresholds */
      82             : static inline void fsleep(unsigned long usecs)
      83             : {
      84             :         if (usecs <= 10)
      85             :                 udelay(usecs);
      86             :         else if (usecs <= 20000)
      87             :                 usleep_range(usecs, 2 * usecs);
      88             :         else
      89             :                 msleep(DIV_ROUND_UP(usecs, 1000));
      90             : }
      91             : 
      92             : #endif /* defined(_LINUX_DELAY_H) */