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Wysocki" , Miguel Ojeda , Danilo Krummrich , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Viresh Kumar , Nishanth Menon , Stephen Boyd Cc: Viresh Kumar , linux-pm@vger.kernel.org, Vincent Guittot , rust-for-linux@vger.kernel.org, Manos Pitsidianakis , Erik Schilling , =?utf-8?q?Alex_Benn=C3=A9e?= , Joakim Bech , Rob Herring , linux-kernel@vger.kernel.org Subject: [PATCH V6 07/15] rust: Add initial bindings for OPP framework Date: Tue, 7 Jan 2025 16:51:40 +0530 Message-Id: <3ca45b4b783d1195305a16f7db4d26b26ff3a192.1736248242.git.viresh.kumar@linaro.org> X-Mailer: git-send-email 2.31.1.272.g89b43f80a514 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 This commit adds initial Rust bindings for the Operating performance points (OPP) core. This adds bindings for `struct dev_pm_opp` and `struct dev_pm_opp_data` to begin with. Reviewed-by: Manos Pitsidianakis Signed-off-by: Viresh Kumar --- MAINTAINERS | 1 + rust/bindings/bindings_helper.h | 1 + rust/kernel/lib.rs | 2 + rust/kernel/opp.rs | 189 ++++++++++++++++++++++++++++++++ 4 files changed, 193 insertions(+) create mode 100644 rust/kernel/opp.rs diff --git a/MAINTAINERS b/MAINTAINERS index 15c8df5b3590..bfcdbe4aa119 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -17579,6 +17579,7 @@ F: Documentation/devicetree/bindings/opp/ F: Documentation/power/opp.rst F: drivers/opp/ F: include/linux/pm_opp.h +F: rust/kernel/opp.rs OPL4 DRIVER M: Clemens Ladisch diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 7a95d999ead8..5f900532e5ec 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -32,6 +32,7 @@ #include #include #include +#include #include #include #include diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 70694becc9ff..16e534024323 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -61,6 +61,8 @@ #[cfg(CONFIG_NET)] pub mod net; pub mod of; +#[cfg(CONFIG_PM_OPP)] +pub mod opp; pub mod page; pub mod pid_namespace; pub mod platform; diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs new file mode 100644 index 000000000000..becb33880c92 --- /dev/null +++ b/rust/kernel/opp.rs @@ -0,0 +1,189 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Operating performance points. +//! +//! This module provides bindings for interacting with the OPP subsystem. +//! +//! C header: [`include/linux/pm_opp.h`](srctree/include/linux/pm_opp.h) + +use crate::{ + bindings, + device::Device, + error::{code::*, to_result, Result}, + types::{ARef, AlwaysRefCounted, Opaque}, +}; + +use core::ptr; + +/// Dynamically created Operating performance point (OPP). +pub struct Token { + dev: ARef, + freq: usize, +} + +impl Token { + /// Adds an OPP dynamically. + pub fn new(dev: &ARef, mut data: Data) -> Result { + // SAFETY: The requirements are satisfied by the existence of `Device` and its safety + // requirements. + to_result(unsafe { bindings::dev_pm_opp_add_dynamic(dev.as_raw(), &mut data.0) })?; + Ok(Self { + dev: dev.clone(), + freq: data.freq(), + }) + } +} + +impl Drop for Token { + fn drop(&mut self) { + // SAFETY: The requirements are satisfied by the existence of `Device` and its safety + // requirements. + unsafe { bindings::dev_pm_opp_remove(self.dev.as_raw(), self.freq) }; + } +} + +/// Equivalent to `struct dev_pm_opp_data` in the C Code. +#[repr(transparent)] +pub struct Data(bindings::dev_pm_opp_data); + +impl Data { + /// Creates new instance of [`Data`]. + pub fn new(freq: usize, u_volt: usize, level: u32, turbo: bool) -> Self { + Self(bindings::dev_pm_opp_data { + turbo, + freq, + u_volt, + level, + }) + } + + /// Adds an OPP dynamically. The OPP is freed once the [`Token`] gets freed. + pub fn add_opp(self, dev: &ARef) -> Result { + Token::new(dev, self) + } + + fn freq(&self) -> usize { + self.0.freq + } +} + +/// Operating performance point (OPP). +/// +/// Wraps the kernel's `struct dev_pm_opp`. +/// +/// The pointer to `struct dev_pm_opp` is non-null and valid for the lifetime of the `OPP` +/// instance. +/// +/// # Invariants +/// +/// Instances of this type are reference-counted. The reference count is incremented by the +/// `dev_pm_opp_get()` function and decremented by `dev_pm_opp_put`. The Rust type `ARef` +/// represents a pointer that owns a reference count on the OPP. +/// +/// A reference to the `OPP`, `&OPP` isn't refcounted by the Rust code. + +#[repr(transparent)] +pub struct OPP(Opaque); + +// SAFETY: It's OK to send the ownership of `OPP` across thread boundaries. +unsafe impl Send for OPP {} + +// SAFETY: It's OK to access `OPP` through shared references from other threads because we're +// either accessing properties that don't change or that are properly synchronised by C code. +unsafe impl Sync for OPP {} + +// SAFETY: The type invariants guarantee that [`OPP`] is always refcounted. +unsafe impl AlwaysRefCounted for OPP { + fn inc_ref(&self) { + // SAFETY: The existence of a shared reference means that the refcount is nonzero. + unsafe { bindings::dev_pm_opp_get(self.0.get()) }; + } + + unsafe fn dec_ref(obj: ptr::NonNull) { + // SAFETY: The safety requirements guarantee that the refcount is nonzero. + unsafe { bindings::dev_pm_opp_put(obj.cast().as_ptr()) } + } +} + +impl OPP { + /// Creates an owned reference to a [`OPP`] from a valid pointer. + /// + /// The refcount is incremented by the C code and will be decremented by `dec_ref()` when the + /// ARef object is dropped. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` is valid and the OPP's refcount is incremented. The + /// caller must also ensure that it doesn't explicitly drop the refcount of the OPP, as the + /// returned ARef object takes over the refcount increment on the underlying object and the + /// same will be dropped along with it. + pub unsafe fn from_raw_opp_owned(ptr: *mut bindings::dev_pm_opp) -> Result> { + let ptr = ptr::NonNull::new(ptr).ok_or(ENODEV)?; + + // SAFETY: The safety requirements guarantee the validity of the pointer. + Ok(unsafe { ARef::from_raw(ptr.cast()) }) + } + + /// Creates a reference to a [`OPP`] from a valid pointer. + /// + /// The refcount is not updated by the Rust API unless the returned reference is converted to + /// an ARef object. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` is valid and remains valid for the duration of 'a. + pub unsafe fn from_raw_opp<'a>(ptr: *mut bindings::dev_pm_opp) -> Result<&'a Self> { + // SAFETY: The caller guarantees that the pointer is not dangling and stays valid for the + // duration of 'a. The cast is okay because `OPP` is `repr(transparent)`. + Ok(unsafe { &*ptr.cast() }) + } + + #[inline] + fn as_raw(&self) -> *mut bindings::dev_pm_opp { + self.0.get() + } + + /// Returns the frequency of an OPP. + pub fn freq(&self, index: Option) -> usize { + let index = index.unwrap_or(0); + + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to + // use it. + unsafe { bindings::dev_pm_opp_get_freq_indexed(self.as_raw(), index) } + } + + /// Returns the voltage of an OPP. + pub fn voltage(&self) -> usize { + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to + // use it. + unsafe { bindings::dev_pm_opp_get_voltage(self.as_raw()) } + } + + /// Returns the level of an OPP. + pub fn level(&self) -> u32 { + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to + // use it. + unsafe { bindings::dev_pm_opp_get_level(self.as_raw()) } + } + + /// Returns the power of an OPP. + pub fn power(&self) -> usize { + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to + // use it. + unsafe { bindings::dev_pm_opp_get_power(self.as_raw()) } + } + + /// Returns the required pstate of an OPP. + pub fn required_pstate(&self, index: u32) -> u32 { + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to + // use it. + unsafe { bindings::dev_pm_opp_get_required_pstate(self.as_raw(), index) } + } + + /// Returns true if the OPP is turbo. + pub fn is_turbo(&self) -> bool { + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to + // use it. + unsafe { bindings::dev_pm_opp_is_turbo(self.as_raw()) } + } +}