Commit a03c9bd9 authored by Alexandre Courbot's avatar Alexandre Courbot Committed by Danilo Krummrich
Browse files

gpu: nova-core: add helper function to wait on condition 

While programming the hardware, we frequently need to busy-wait until
a condition (like a given bit of a register to switch value) happens.

Add a basic `wait_on` helper function to wait on such conditions
expressed as a closure, with a timeout argument.

This is temporary as we will switch to `read_poll_timeout` [1] once it
is available.

Link: https://lore.kernel.org/lkml/20250220070611.214262-8-fujita.tomonori@gmail.com/

 [1]
Signed-off-by: default avatarAlexandre Courbot <acourbot@nvidia.com>
Link: https://lore.kernel.org/r/20250619-nova-frts-v6-11-ecf41ef99252@nvidia.com


Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
parent 94a08721

drivers/gpu/nova-core/util.rs

+29 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0



use core::time::Duration;



use kernel::prelude::*;

use kernel::time::Instant;



pub(crate) const fn to_lowercase_bytes<const N: usize>(s: &str) -> [u8; N] {

    let src = s.as_bytes();

    let mut dst = [0; N];
@@ -19,3 +24,27 @@ pub(crate) const fn const_bytes_to_str(bytes: &[u8]) -> &str { 
        Err(_) => kernel::build_error!("Bytes are not valid UTF-8."),

    }

}



/// Wait until `cond` is true or `timeout` elapsed.

///

/// When `cond` evaluates to `Some`, its return value is returned.

///

/// `Err(ETIMEDOUT)` is returned if `timeout` has been reached without `cond` evaluating to

/// `Some`.

///

/// TODO: replace with `read_poll_timeout` once it is available.

/// (https://lore.kernel.org/lkml/20250220070611.214262-8-fujita.tomonori@gmail.com/)

#[expect(dead_code)]

pub(crate) fn wait_on<R, F: Fn() -> Option<R>>(timeout: Duration, cond: F) -> Result<R> {

    let start_time = Instant::now();



    loop {

        if let Some(ret) = cond() {

            return Ok(ret);

        }



        if start_time.elapsed().as_nanos() > timeout.as_nanos() as i64 {

            return Err(ETIMEDOUT);

        }

    }

}