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] 22 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] 38 pub fn from_raw(inner: bindings::ktime_t) -> Self { 39 Self { inner } 40 } 41 42 /// Get the current time using `CLOCK_MONOTONIC`. 43 #[inline] 44 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] 51 fn divns_constant<const DIV: i64>(self) -> i64 { 52 self.to_ns() / DIV 53 } 54 55 /// Returns the number of nanoseconds. 56 #[inline] 57 pub fn to_ns(self) -> i64 { 58 self.inner 59 } 60 61 /// Returns the number of milliseconds. 62 #[inline] 63 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] 70 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] 78 fn sub(self, other: Ktime) -> Ktime { 79 Self { 80 inner: self.inner - other.inner, 81 } 82 } 83 } 84