linux/rust/kernel/time.rs, branch v6.17

rust: time: Add wrapper for fsleep() function

2025-06-30T11:22:05Z

Add a wrapper for fsleep(), flexible sleep functions in include/linux/delay.h which typically deals with hardware delays. The kernel supports several sleep functions to handle various lengths of delay. This adds fsleep(), automatically chooses the best sleep method based on a duration. fsleep() can only be used in a nonatomic context. This requirement is not checked by these abstractions, but it is intended that klint [1] or a similar tool will be used to check it in the future. Link: https://rust-for-linux.com/klint [1] Reviewed-by: Gary Guo Reviewed-by: Alice Ryhl Reviewed-by: Fiona Behrens Tested-by: Daniel Almeida Reviewed-by: Andreas Hindborg Signed-off-by: FUJITA Tomonori Link: https://lore.kernel.org/r/20250617144155.3903431-3-fujita.tomonori@gmail.com Signed-off-by: Andreas Hindborg

rust: time: Add HrTimerExpires trait

2025-06-24T17:52:47Z

Introduce the `HrTimerExpires` trait to represent types that can be used as expiration values for high-resolution timers. Define a required method, `into_nanos()`, which returns the expiration time as a raw nanosecond value suitable for use with C's hrtimer APIs. Also extend the `HrTimerMode` to use the `HrTimerExpires` trait. This refactoring is a preparation for enabling hrtimer code to work uniformly with both absolute and relative expiration modes. Reviewed-by: Andreas Hindborg Signed-off-by: FUJITA Tomonori Link: https://lore.kernel.org/r/20250610132823.3457263-4-fujita.tomonori@gmail.com [ changed conversion method names to `as_*` - Andreas ] Signed-off-by: Andreas Hindborg

rust: time: Add ktime_get() to ClockSource trait

2025-06-16T13:02:29Z

Introduce the ktime_get() associated function to the ClockSource trait, allowing each clock source to specify how it retrieves the current time. This enables Instant::now() to be implemented generically using the type-level ClockSource abstraction. This change enhances the type safety and extensibility of timekeeping by statically associating time retrieval mechanisms with their respective clock types. It also reduces the reliance on hardcoded clock logic within Instant. Signed-off-by: FUJITA Tomonori Link: https://lore.kernel.org/r/20250610093258.3435874-4-fujita.tomonori@gmail.com Signed-off-by: Andreas Hindborg

rust: time: Make Instant generic over ClockSource

2025-06-16T13:01:56Z

Refactor the Instant type to be generic over a ClockSource type parameter, enabling static enforcement of clock correctness across APIs that deal with time. Previously, the clock source was implicitly fixed (typically CLOCK_MONOTONIC), and developers had to ensure compatibility manually. This design eliminates runtime mismatches between clock sources, and enables stronger type-level guarantees throughout the timer subsystem. Reviewed-by: Andreas Hindborg Reviewed-by: Boqun Feng Signed-off-by: FUJITA Tomonori Link: https://lore.kernel.org/r/20250610093258.3435874-3-fujita.tomonori@gmail.com Signed-off-by: Andreas Hindborg

rust: time: Replace ClockId enum with ClockSource trait

2025-06-16T13:01:37Z

Replace the ClockId enum with a trait-based abstraction called ClockSource. This change enables expressing clock sources as types and leveraging the Rust type system to enforce clock correctness at compile time. This also sets the stage for future generic abstractions over Instant types such as Instant. Reviewed-by: Andreas Hindborg Reviewed-by: Boqun Feng Signed-off-by: FUJITA Tomonori Link: https://lore.kernel.org/r/20250610093258.3435874-2-fujita.tomonori@gmail.com Signed-off-by: Andreas Hindborg

rust: time: Avoid 64-bit integer division on 32-bit architectures

2025-06-16T13:01:15Z

Avoid 64-bit integer division that 32-bit architectures don't implement generally. This uses ktime_to_us() and ktime_to_ms() instead. The time abstraction needs i64 / u32 division so C's div_s64() can be used but ktime_to_us() and ktime_to_ms() provide a simpler solution for this time abstraction problem on 32-bit architectures. 32-bit ARM is the only 32-bit architecture currently supported by Rust. Using the cfg attribute, only 32-bit architectures will call ktime_to_us() and ktime_to_ms(), while the other 64-bit architectures will continue to use the current code as-is to avoid the overhead. One downside of calling the C's functions is that the as_micros/millis methods can no longer be const fn. We stick with the simpler approach unless there's a compelling need for a const fn. Suggested-by: Arnd Bergmann Suggested-by: Boqun Feng Signed-off-by: FUJITA Tomonori Reviewed-by: Andreas Hindborg Link: https://lore.kernel.org/r/20250502004524.230553-1-fujita.tomonori@gmail.com Signed-off-by: Andreas Hindborg

rust: time: Introduce Instant type

2025-04-29T13:31:07Z

Introduce a type representing a specific point in time. We could use the Ktime type but C's ktime_t is used for both timestamp and timedelta. To avoid confusion, introduce a new Instant type for timestamp. Rename Ktime to Instant and modify their methods for timestamp. Implement the subtraction operator for Instant: Delta = Instant A - Instant B Reviewed-by: Boqun Feng Reviewed-by: Gary Guo Reviewed-by: Fiona Behrens Tested-by: Daniel Almeida Reviewed-by: Andreas Hindborg Signed-off-by: FUJITA Tomonori Link: https://lore.kernel.org/r/20250423192857.199712-5-fujita.tomonori@gmail.com Signed-off-by: Andreas Hindborg

rust: time: Introduce Delta type

2025-04-29T13:31:07Z

Introduce a type representing a span of time. Define our own type because `core::time::Duration` is large and could panic during creation. time::Ktime could be also used for time duration but timestamp and timedelta are different so better to use a new type. i64 is used instead of u64 to represent a span of time; some C drivers uses negative Deltas and i64 is more compatible with Ktime using i64 too (e.g., ktime_[us|ms]_delta() APIs return i64 so we create Delta object without type conversion. i64 is used instead of bindings::ktime_t because when the ktime_t type is used as timestamp, it represents values from 0 to KTIME_MAX, which is different from Delta. as_millis() method isn't used in this patchset. It's planned to be used in Binder driver. Reviewed-by: Andrew Lunn Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo Reviewed-by: Fiona Behrens Tested-by: Daniel Almeida Reviewed-by: Andreas Hindborg Signed-off-by: FUJITA Tomonori Link: https://lore.kernel.org/r/20250423192857.199712-4-fujita.tomonori@gmail.com Signed-off-by: Andreas Hindborg

rust: time: Add PartialEq/Eq/PartialOrd/Ord trait to Ktime

2025-04-29T13:31:07Z

Add PartialEq/Eq/PartialOrd/Ord trait to Ktime so two Ktime instances can be compared to determine whether a timeout is met or not. Use the derive implements; we directly touch C's ktime_t rather than using the C's accessors because it is more efficient and we already do in the existing code (Ktime::sub). Reviewed-by: Trevor Gross Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo Reviewed-by: Fiona Behrens Tested-by: Daniel Almeida Reviewed-by: Andreas Hindborg Signed-off-by: FUJITA Tomonori Link: https://lore.kernel.org/r/20250423192857.199712-3-fujita.tomonori@gmail.com Signed-off-by: Andreas Hindborg

rust: hrtimer: add clocksource selection through `ClockId`

2025-03-22T11:08:54Z

Allow selecting a clock source for timers by passing a `ClockId` variant to `HrTimer::new`. Acked-by: Frederic Weisbecker Acked-by: Thomas Gleixner Reviewed-by: Lyude Paul Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250309-hrtimer-v3-v6-12-rc2-v12-12-73586e2bd5f1@kernel.org Signed-off-by: Andreas Hindborg