While rebasing rvkms I noticed that timers I was setting seemed to have
pretty random timer values that amounted slightly over 2x the time value I
set each time. After a lot of debugging, I finally managed to figure out
why: it seems that since we moved to Instant and Delta, we mistakenly
began passing the clocksource ID to hrtimer_start_range_ns, when we should
be passing the timer mode instead. Presumably, this works fine for simple
relative timers - but immediately breaks on other types of timers.

So, fix this by passing the ID for the timer mode instead.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Acked-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Fixes: e0c0ab04f678 ("rust: time: Make HasHrTimer generic over HrTimerMode")
Link: https://lore.kernel.org/r/20250710225129.670051-1-lyude@redhat.com
[ Removed cast, applied `rustfmt`, fixed `Fixes:` tag. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Pull timekeeping updates from Andreas Hindborg:

 - Make 'Instant' generic over clock source. This allows the compiler to
   assert that arithmetic expressions involving the 'Instant' use
   'Instants' based on the same clock source.

 - Make 'HrTimer' generic over the timer mode. 'HrTimer' timers take a
   'Duration' or an 'Instant' when setting the expiry time, depending on
   the timer mode. With this change, the compiler can check the type
   matches the timer mode.

 - Add an abstraction for 'fsleep'. 'fsleep' is a flexible sleep
   function that will select an appropriate sleep method depending on
   the requested sleep time.

 - Avoid 64-bit divisions on 32-bit hardware when calculating
   timestamps.

 - Seal the 'HrTimerMode' trait. This prevents users of the
   'HrTimerMode' from implementing the trait on their own types.

* tag 'rust-timekeeping-for-v6.17' of https://github.com/Rust-for-Linux/linux:
  rust: time: Add wrapper for fsleep() function
  rust: time: Seal the HrTimerMode trait
  rust: time: Remove Ktime in hrtimer
  rust: time: Make HasHrTimer generic over HrTimerMode
  rust: time: Add HrTimerExpires trait
  rust: time: Replace HrTimerMode enum with trait-based mode types
  rust: time: Add ktime_get() to ClockSource trait
  rust: time: Make Instant generic over ClockSource
  rust: time: Replace ClockId enum with ClockSource trait
  rust: time: Avoid 64-bit integer division on 32-bit architectures

In the previous patch we added Opaque::cast_from() that performs the
opposite operation to Opaque::raw_get(). For consistency with this
naming, rename raw_get() to cast_from().

There are a few other options such as calling cast_from() something
closer to raw_get() rather than renaming this method. However, I could
not find a great naming scheme that works with raw_get(). The previous
version of this patch used from_raw(), but functions of that name
typically have a different signature, so that's not a great option.

Suggested-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Benno Lossin <lossin@kernel.org>
Acked-by: Andreas Hindborg <a.hindborg@kernel.org>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250624-opaque-from-raw-v2-2-e4da40bdc59c@google.com
[ Removed `HrTimer::raw_get` change. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Prevent downstream crates or drivers from implementing `HrTimerMode`
for arbitrary types, which could otherwise leads to unsupported
behavior.

Introduce a `private::Sealed` trait and implement it for all types
that implement `HrTimerMode`.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20250617232806.3950141-1-fujita.tomonori@gmail.com
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>

Remove the use of `Ktime` from the hrtimer code, which was originally
introduced as a temporary workaround. The hrtimer has now been fully
converted to use the `Instant` and `Delta` types instead.

Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Link: https://lore.kernel.org/r/20250610132823.3457263-6-fujita.tomonori@gmail.com
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>

Add a `TimerMode` associated type to the `HasHrTimer` trait to
represent the operational mode of the timer, such as absolute or
relative expiration. This new type must implement the `HrTimerMode`
trait, which defines how expiration values are interpreted.

Update the `start()` method to accept an `expires` parameter of type
`<Self::TimerMode as HrTimerMode>::Expires` instead of the fixed `Ktime`.
This enables different timer modes to provide strongly typed expiration
values, such as `Instant<C>` or `Delta`.

The `impl_has_hr_timer` macro is also extended to allow specifying the
`HrTimerMode`. In the following example, it guarantees that the
`start()` method for `Foo` only accepts `Instant<Monotonic>`. Using a
`Delta` or an `Instant` with a different clock source will result in a
compile-time error:

struct Foo {
    #[pin]
    timer: HrTimer<Self>,
}

impl_has_hr_timer! {
    impl HasHrTimer<Self> for Foo {
        mode : AbsoluteMode<Monotonic>,
        field : self.timer
    }
}

This design eliminates runtime mismatches between expires types and
clock sources, and enables stronger type-level guarantees throughout
hrtimer.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://lore.kernel.org/r/20250610132823.3457263-5-fujita.tomonori@gmail.com
[ changed conversion method names to `as_*` - Andreas ]
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>

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 <a.hindborg@kernel.org>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
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 <a.hindborg@kernel.org>

Replace the `HrTimerMode` enum with a trait-based approach that uses
zero-sized types to represent each mode of operation. Each mode now
implements the `HrTimerMode` trait.

This refactoring is a preparation for replacing raw `Ktime` in HrTimer
with the `Instant` and `Delta` types, and for making `HrTimer` generic
over a `ClockSource`.

Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Link: https://lore.kernel.org/r/20250610132823.3457263-3-fujita.tomonori@gmail.com
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>

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<C>.

Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Link: https://lore.kernel.org/r/20250610093258.3435874-2-fujita.tomonori@gmail.com
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>

Fix a compile error in the `impl_has_hr_timer!` macro as follows:

error[E0599]: no method named cast_mut found for raw pointer *mut Foo in the current scope

The `container_of!` macro already returns a mutable pointer when used
in a `*mut T` context so the `.cast_mut()` method is not available.

[ We missed this one because there is no caller yet and it is
  a macro. - Miguel ]

Fixes: 74d6a606c2b3 ("rust: retain pointer mut-ness in `container_of!`")
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Acked-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://lore.kernel.org/r/20250606020505.3186533-1-fujita.tomonori@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>