From: Deborah Brouwer <[email protected]> Provide a safe Rust wrapper for arch_timer_get_rate().
The Rust binding calls a C helper that returns 0 when the ARM architectural timer is not available or not yet initialized. Map this to Option<u32> to make the absence of a valid rate explicit to Rust callers. This allows Rust drivers to query the system timer frequency and select appropriate time sources when programming hardware timeouts. Signed-off-by: Deborah Brouwer <[email protected]> Signed-off-by: Laura Nao <[email protected]> --- rust/helpers/time.c | 6 ++++++ rust/kernel/time.rs | 30 ++++++++++++++++++++++++++++++ 2 files changed, 36 insertions(+) diff --git a/rust/helpers/time.c b/rust/helpers/time.c index 32f495970493..70fda31bd758 100644 --- a/rust/helpers/time.c +++ b/rust/helpers/time.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 +#include <clocksource/arm_arch_timer.h> #include <linux/delay.h> #include <linux/ktime.h> #include <linux/timekeeping.h> @@ -38,3 +39,8 @@ __rust_helper void rust_helper_udelay(unsigned long usec) { udelay(usec); } + +__rust_helper u32 rust_helper_arch_timer_get_rate(void) +{ + return arch_timer_get_rate(); +} diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs index 6c0a5e8090d0..6c48ce21984a 100644 --- a/rust/kernel/time.rs +++ b/rust/kernel/time.rs @@ -423,6 +423,36 @@ fn div(self, rhs: Self) -> Self::Output { } } +/// Returns the ARM architecture timer frequency in Hz, if available. +/// +/// This function queries the system-wide ARM architecture timer frequency. +/// The architecture timer provides a consistent time source across all CPU cores. +/// +/// Returns `None` if: +/// - The ARM architecture timer is not available (`CONFIG_ARM_ARCH_TIMER` not enabled) +/// - The timer rate is zero (not initialized) +/// +/// # Examples +/// +/// ``` +/// use kernel::time::arch_timer_get_rate; +/// +/// if let Some(rate) = arch_timer_get_rate() { +/// // Use `rate`. +/// } +/// ``` +pub fn arch_timer_get_rate() -> Option<u32> { + // SAFETY: The C helper is available in all configs; it calls + // `arch_timer_get_rate()`, which falls back to an inline stub returning 0 + // when CONFIG_ARM_ARCH_TIMER is disabled. + let rate = unsafe { bindings::arch_timer_get_rate() }; + if rate == 0 { + None + } else { + Some(rate) + } +} + impl Delta { /// A span of time equal to zero. pub const ZERO: Self = Self { value: 0 }; -- 2.39.5
