1 // SPDX-License-Identifier: GPL-2.0
2 
3 //! Time related primitives.
4 //!
5 //! This module contains the kernel APIs related to time and timers that
6 //! have been ported or wrapped for usage by Rust code in the kernel.
7 //!
8 //! C header: [`include/linux/jiffies.h`](srctree/include/linux/jiffies.h).
9 //! C header: [`include/linux/ktime.h`](srctree/include/linux/ktime.h).
10 
11 /// The number of nanoseconds per millisecond.
12 pub const NSEC_PER_MSEC: i64 = bindings::NSEC_PER_MSEC as i64;
13 
14 /// The time unit of Linux kernel. One jiffy equals (1/HZ) second.
15 pub type Jiffies = core::ffi::c_ulong;
16 
17 /// The millisecond time unit.
18 pub type Msecs = core::ffi::c_uint;
19 
20 /// Converts milliseconds to jiffies.
21 #[inline]
msecs_to_jiffies(msecs: Msecs) -> Jiffies22 pub fn msecs_to_jiffies(msecs: Msecs) -> Jiffies {
23     // SAFETY: The `__msecs_to_jiffies` function is always safe to call no
24     // matter what the argument is.
25     unsafe { bindings::__msecs_to_jiffies(msecs) }
26 }
27 
28 /// A Rust wrapper around a `ktime_t`.
29 #[repr(transparent)]
30 #[derive(Copy, Clone)]
31 pub struct Ktime {
32     inner: bindings::ktime_t,
33 }
34 
35 impl Ktime {
36     /// Create a `Ktime` from a raw `ktime_t`.
37     #[inline]
from_raw(inner: bindings::ktime_t) -> Self38     pub fn from_raw(inner: bindings::ktime_t) -> Self {
39         Self { inner }
40     }
41 
42     /// Get the current time using `CLOCK_MONOTONIC`.
43     #[inline]
ktime_get() -> Self44     pub fn ktime_get() -> Self {
45         // SAFETY: It is always safe to call `ktime_get` outside of NMI context.
46         Self::from_raw(unsafe { bindings::ktime_get() })
47     }
48 
49     /// Divide the number of nanoseconds by a compile-time constant.
50     #[inline]
divns_constant<const DIV: i64>(self) -> i6451     fn divns_constant<const DIV: i64>(self) -> i64 {
52         self.to_ns() / DIV
53     }
54 
55     /// Returns the number of nanoseconds.
56     #[inline]
to_ns(self) -> i6457     pub fn to_ns(self) -> i64 {
58         self.inner
59     }
60 
61     /// Returns the number of milliseconds.
62     #[inline]
to_ms(self) -> i6463     pub fn to_ms(self) -> i64 {
64         self.divns_constant::<NSEC_PER_MSEC>()
65     }
66 }
67 
68 /// Returns the number of milliseconds between two ktimes.
69 #[inline]
ktime_ms_delta(later: Ktime, earlier: Ktime) -> i6470 pub fn ktime_ms_delta(later: Ktime, earlier: Ktime) -> i64 {
71     (later - earlier).to_ms()
72 }
73 
74 impl core::ops::Sub for Ktime {
75     type Output = Ktime;
76 
77     #[inline]
sub(self, other: Ktime) -> Ktime78     fn sub(self, other: Ktime) -> Ktime {
79         Self {
80             inner: self.inner - other.inner,
81         }
82     }
83 }
84