| 1 |
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| 2 | #ifndef _LINUX_DELAY_H
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| 3 | #define _LINUX_DELAY_H
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| 4 |
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| 5 | |
| 6 | * Copyright (C) 1993 Linus Torvalds
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| 7 | *
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| 8 | * Delay routines, using a pre-computed "loops_per_jiffy" value.
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| 9 | * Sleep routines using timer list timers or hrtimers.
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| 10 |
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| 11 |
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| 12 | #include <linux/math.h>
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| 13 | #include <linux/sched.h>
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| 14 | #include <linux/jiffies.h>
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| 15 |
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| 16 | extern unsigned long loops_per_jiffy;
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| 17 |
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| 18 | #include <asm/delay.h>
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| 19 |
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| 20 | |
| 21 | * Using udelay() for intervals greater than a few milliseconds can
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| 22 | * risk overflow for high loops_per_jiffy (high bogomips) machines. The
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| 23 | * mdelay() provides a wrapper to prevent this. For delays greater
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| 24 | * than MAX_UDELAY_MS milliseconds, the wrapper is used. Architecture
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| 25 | * specific values can be defined in asm-???/delay.h as an override.
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| 26 | * The 2nd mdelay() definition ensures GCC will optimize away the
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| 27 | * while loop for the common cases where n <= MAX_UDELAY_MS -- Paul G.
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| 28 |
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| 29 | #ifndef MAX_UDELAY_MS
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| 30 | #define MAX_UDELAY_MS 5
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| 31 | #endif
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| 32 |
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| 33 | #ifndef mdelay
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| 34 | |
| 35 | * mdelay - Inserting a delay based on milliseconds with busy waiting
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| 36 | * @n: requested delay in milliseconds
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| 37 | *
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| 38 | * See udelay() for basic information about mdelay() and it's variants.
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| 39 | *
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| 40 | * Please double check, whether mdelay() is the right way to go or whether a
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| 41 | * refactoring of the code is the better variant to be able to use msleep()
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| 42 | * instead.
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| 43 |
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| 44 | #define mdelay(n) (\
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| 45 | (__builtin_constant_p(n) && (n)<=MAX_UDELAY_MS) ? udelay((n)*1000) : \
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| 46 | ({unsigned long __ms=(n); while (__ms--) udelay(1000);}))
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| 47 | #endif
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| 48 |
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| 49 | #ifndef ndelay
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| 50 | static inline void ndelay(unsigned long x)
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| 51 | {
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| 52 | udelay(DIV_ROUND_UP(x, 1000));
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| 53 | }
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| 54 | #define ndelay(x) ndelay(x)
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| 55 | #endif
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| 56 |
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| 57 | extern unsigned long lpj_fine;
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| 58 | void calibrate_delay(void);
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| 59 | unsigned long calibrate_delay_is_known(void);
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| 60 | void __attribute__((weak)) calibration_delay_done(void);
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| 61 | void msleep(unsigned int msecs);
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| 62 | unsigned long msleep_interruptible(unsigned int msecs);
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| 63 | void usleep_range_state(unsigned long min, unsigned long max,
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| 64 | unsigned int state);
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| 65 |
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| 66 | |
| 67 | * usleep_range - Sleep for an approximate time
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| 68 | * @min: Minimum time in microseconds to sleep
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| 69 | * @max: Maximum time in microseconds to sleep
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| 70 | *
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| 71 | * For basic information please refer to usleep_range_state().
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| 72 | *
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| 73 | * The task will be in the state TASK_UNINTERRUPTIBLE during the sleep.
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| 74 |
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| 75 | static inline void usleep_range(unsigned long min, unsigned long max)
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| 76 | {
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| 77 | usleep_range_state(min, max, TASK_UNINTERRUPTIBLE);
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| 78 | }
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| 79 |
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| 80 | |
| 81 | * usleep_range_idle - Sleep for an approximate time with idle time accounting
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| 82 | * @min: Minimum time in microseconds to sleep
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| 83 | * @max: Maximum time in microseconds to sleep
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| 84 | *
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| 85 | * For basic information please refer to usleep_range_state().
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| 86 | *
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| 87 | * The sleeping task has the state TASK_IDLE during the sleep to prevent
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| 88 | * contribution to the load average.
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| 89 |
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| 90 | static inline void usleep_range_idle(unsigned long min, unsigned long max)
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| 91 | {
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| 92 | usleep_range_state(min, max, TASK_IDLE);
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| 93 | }
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| 94 |
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| 95 | |
| 96 | * ssleep - wrapper for seconds around msleep
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| 97 | * @seconds: Requested sleep duration in seconds
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| 98 | *
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| 99 | * Please refer to msleep() for detailed information.
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| 100 |
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| 101 | static inline void ssleep(unsigned int seconds)
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| 102 | {
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| 103 | msleep(seconds * 1000);
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| 104 | }
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| 105 |
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| 106 | static const unsigned int max_slack_shift = 2;
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| 107 | #define USLEEP_RANGE_UPPER_BOUND ((TICK_NSEC << max_slack_shift) / NSEC_PER_USEC)
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| 108 |
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| 109 | |
| 110 | * fsleep - flexible sleep which autoselects the best mechanism
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| 111 | * @usecs: requested sleep duration in microseconds
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| 112 | *
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| 113 | * fsleep() selects the best mechanism that will provide maximum 25% slack
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| 114 | * to the requested sleep duration. Therefore it uses:
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| 115 | *
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| 116 | * * udelay() loop for sleep durations <= 10 microseconds to avoid hrtimer
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| 117 | * overhead for really short sleep durations.
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| 118 | * * usleep_range() for sleep durations which would lead with the usage of
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| 119 | * msleep() to a slack larger than 25%. This depends on the granularity of
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| 120 | * jiffies.
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| 121 | * * msleep() for all other sleep durations.
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| 122 | *
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| 123 | * Note: When %CONFIG_HIGH_RES_TIMERS is not set, all sleeps are processed with
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| 124 | * the granularity of jiffies and the slack might exceed 25% especially for
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| 125 | * short sleep durations.
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| 126 |
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| 127 | static inline void fsleep(unsigned long usecs)
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| 128 | {
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| 129 | if (usecs <= 10)
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| 130 | udelay(usecs);
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| 131 | else if (usecs < USLEEP_RANGE_UPPER_BOUND)
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| 132 | usleep_range(usecs, usecs + (usecs >> max_slack_shift));
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| 133 | else
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| 134 | msleep(DIV_ROUND_UP(usecs, USEC_PER_MSEC));
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| 135 | }
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| 136 |
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| 137 | #endif
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