Add a helper function to poll periodically until a condition is met or
a timeout is reached. By using the function, the 7th patch fixes
QT2025 PHY driver to sleep until the hardware becomes ready.

As a result of the past discussion, this introduces two new types,
Instant and Delta, which represent a specific point in time and a span
of time, respectively.

Unlike the old rust branch, This adds a wrapper for fsleep() instead
of msleep(). fsleep() automatically chooses the best sleep method
based on a duration.

Add __might_sleep_precision(), rust friendly version of
__might_sleep(), which takes a pointer to a string with the length.
core::panic::Location::file() doesn't provide a null-terminated string
so a work around is necessary to use __might_sleep(). Providing a
null-terminated string for better C interoperability is under
discussion [1].

[1]: https://github.com/rust-lang/libs-team/issues/466

v8:
- fix compile warnings
v7: https://lore.kernel.org/lkml/20241220061853.2782878-1-fujita.tomonori@gmail.com/ (local)
- rebased on rust-next
- use crate::ffi instead of core::ffi
v6: https://lore.kernel.org/lkml/20241114070234.116329-1-fujita.tomonori@gmail.com/ (local)
- use super::Delta in delay.rs
- improve the comments
- add Delta's is_negative() method
- rename processor.rs to cpu.rs for cpu_relax()
- add __might_sleep_precision() taking pointer to a string with the length
- implement read_poll_timeout as normal function instead of macro
v5: https://lore.kernel.org/lkml/20241101010121.69221-1-fujita.tomonori@gmail.com/ (local)
- set the range of Delta for fsleep function
- update comments
v4: https://lore.kernel.org/lkml/20241025033118.44452-1-fujita.tomonori@gmail.com/ (local)
- rebase on the tip tree's timers/core
- add Instant instead of using Ktime
- remove unused basic methods
- add Delta as_micros_ceil method
- use const fn for Delta from_* methods
- add more comments based on the feedback
- add a safe wrapper for cpu_relax()
- add __might_sleep() macro
v3: https://lore.kernel.org/lkml/20241016035214.2229-1-fujita.tomonori@gmail.com/ (local)
- Update time::Delta methods (use i64 for everything)
- Fix read_poll_timeout to show the proper debug info (file and line)
- Move fsleep to rust/kernel/time/delay.rs
- Round up delta for fsleep
- Access directly ktime_t instead of using ktime APIs
- Add Eq and Ord with PartialEq and PartialOrd
v2: https://lore.kernel.org/lkml/20241005122531.20298-1-fujita.tomonori@gmail.com/ (local)
- Introduce time::Delta instead of core::time::Duration
- Add some trait to Ktime for calculating timeout
- Use read_poll_timeout in QT2025 driver instead of using fsleep directly
v1: https://lore.kernel.org/netdev/20241001112512.4861-1-fujita.tomonori@gmail.com/ (local)

FUJITA Tomonori (7):
  rust: time: Add PartialEq/Eq/PartialOrd/Ord trait to Ktime
  rust: time: Introduce Delta type
  rust: time: Introduce Instant type
  rust: time: Add wrapper for fsleep function
  MAINTAINERS: rust: Add TIMEKEEPING and TIMER abstractions
  rust: Add read_poll_timeout functions
  net: phy: qt2025: Wait until PHY becomes ready

 MAINTAINERS               |   2 +
 drivers/net/phy/qt2025.rs |  10 +++-
 include/linux/kernel.h    |   2 +
 kernel/sched/core.c       |  28 +++++++++--
 rust/helpers/helpers.c    |   2 +
 rust/helpers/kernel.c     |  13 +++++
 rust/helpers/time.c       |   8 +++
 rust/kernel/cpu.rs        |  13 +++++
 rust/kernel/error.rs      |   1 +
 rust/kernel/io.rs         |   5 ++
 rust/kernel/io/poll.rs    |  84 +++++++++++++++++++++++++++++++
 rust/kernel/lib.rs        |   2 +
 rust/kernel/time.rs       | 103 ++++++++++++++++++++++++++++----------
 rust/kernel/time/delay.rs |  43 ++++++++++++++++
 14 files changed, 283 insertions(+), 33 deletions(-)
 create mode 100644 rust/helpers/kernel.c
 create mode 100644 rust/helpers/time.c
 create mode 100644 rust/kernel/cpu.rs
 create mode 100644 rust/kernel/io.rs
 create mode 100644 rust/kernel/io/poll.rs
 create mode 100644 rust/kernel/time/delay.rs


base-commit: ceff0757f5dafb5be5205988171809c877b1d3e3
-- 
2.43.0