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Wysocki" , Miguel Ojeda , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl Cc: Viresh Kumar , linux-pm@vger.kernel.org, Vincent Guittot , Stephen Boyd , Nishanth Menon , 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: [RFC PATCH V2 4/8] rust: Add initial bindings for cpufreq framework Date: Fri, 7 Jun 2024 14:42:19 +0530 Message-Id: <8a53d1e0bf52f02027ff4be2296bf59088bbd163.1717750631.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 cpufreq core. This adds basic bindings for cpufreq flags, relations and cpufreq table. Signed-off-by: Viresh Kumar Reviewed-by: Manos Pitsidianakis --- rust/bindings/bindings_helper.h | 1 + rust/helpers.c | 15 ++ rust/kernel/cpufreq.rs | 251 ++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 2 + 4 files changed, 269 insertions(+) create mode 100644 rust/kernel/cpufreq.rs diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 0465b03828b8..9ae8aab41c53 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -7,6 +7,7 @@ */ #include +#include #include #include #include diff --git a/rust/helpers.c b/rust/helpers.c index 25cc8adac468..35c8b66d258f 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -24,6 +24,7 @@ #include #include #include +#include #include #include #include @@ -230,6 +231,20 @@ void rust_helper_cpumask_setall(struct cpumask *dstp) } EXPORT_SYMBOL_GPL(rust_helper_cpumask_setall); +#ifdef CONFIG_CPU_FREQ +unsigned int rust_helper_cpufreq_table_len(struct cpufreq_frequency_table *freq_table) +{ + return cpufreq_table_len(freq_table); +} +EXPORT_SYMBOL_GPL(rust_helper_cpufreq_table_len); + +void rust_helper_cpufreq_register_em_with_opp(struct cpufreq_policy *policy) +{ + cpufreq_register_em_with_opp(policy); +} +EXPORT_SYMBOL_GPL(rust_helper_cpufreq_register_em_with_opp); +#endif + #ifndef CONFIG_OF_DYNAMIC struct device_node *rust_helper_of_node_get(struct device_node *node) { diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs new file mode 100644 index 000000000000..51a4a9bd8d3c --- /dev/null +++ b/rust/kernel/cpufreq.rs @@ -0,0 +1,251 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! CPU frequency scaling. +//! +//! This module provides bindings for interacting with the cpufreq subsystem. +//! +//! C header: [`include/linux/cpufreq.h`](../../../../../../include/linux/cpufreq.h) + +use crate::{ + bindings, + error::{code::*, to_result, Result}, + prelude::*, +}; + +use core::{ + pin::Pin, +}; + +/// Default transition latency value. +pub const ETERNAL_LATENCY: u32 = bindings::CPUFREQ_ETERNAL as u32; + +/// Container for cpufreq driver flags. +pub mod flags { + use crate::bindings; + + /// Set by drivers that need to update internal upper and lower boundaries along with the + /// target frequency and so the core and governors should also invoke the driver if the target + /// frequency does not change, but the policy min or max may have changed. + pub const NEED_UPDATE_LIMITS: u16 = bindings::CPUFREQ_NEED_UPDATE_LIMITS as _; + + /// Set by drivers for platforms where loops_per_jiffy or other kernel "constants" aren't + /// affected by frequency transitions. + pub const CONST_LOOPS: u16 = bindings::CPUFREQ_CONST_LOOPS as _; + + /// Set by drivers that want the core to automatically register the cpufreq driver as a thermal + /// cooling device. + pub const IS_COOLING_DEV: u16 = bindings::CPUFREQ_IS_COOLING_DEV as _; + + /// Set by drivers for platforms that have multiple clock-domains, i.e. supporting multiple + /// policies. With this sysfs directories of governor would be created in cpu/cpuN/cpufreq/ + /// directory and so they can use the same governor with different tunables for different + /// clusters. + pub const HAVE_GOVERNOR_PER_POLICY: u16 = bindings::CPUFREQ_HAVE_GOVERNOR_PER_POLICY as _; + + /// Set by drivers which do POSTCHANGE notifications from outside of their ->target() routine. + pub const ASYNC_NOTIFICATION: u16 = bindings::CPUFREQ_ASYNC_NOTIFICATION as _; + + /// Set by drivers that want cpufreq core to check if CPU is running at a frequency present in + /// freq-table exposed by the driver. For these drivers if CPU is found running at an out of + /// table freq, the cpufreq core will try to change the frequency to a value from the table. + /// And if that fails, it will stop further boot process by issuing a BUG_ON(). + pub const NEED_INITIAL_FREQ_CHECK: u16 = bindings::CPUFREQ_NEED_INITIAL_FREQ_CHECK as _; + + /// Set by drivers to disallow use of governors with "dynamic_switching" flag set. + pub const NO_AUTO_DYNAMIC_SWITCHING: u16 = bindings::CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING as _; +} + +/// CPU frequency selection relations. Each value contains a `bool` argument which corresponds to +/// the Relation being efficient. +#[derive(Copy, Clone, Debug, Eq, PartialEq)] +pub enum Relation { + /// Select the lowest frequency at or above target. + Low(bool), + /// Select the highest frequency below or at target. + High(bool), + /// Select the closest frequency to the target. + Close(bool), +} + +impl Relation { + // Converts from a value compatible with the C code. + fn new(val: u32) -> Result { + let efficient = val & bindings::CPUFREQ_RELATION_E != 0; + + Ok(match val & !bindings::CPUFREQ_RELATION_E { + bindings::CPUFREQ_RELATION_L => Self::Low(efficient), + bindings::CPUFREQ_RELATION_H => Self::High(efficient), + bindings::CPUFREQ_RELATION_C => Self::Close(efficient), + _ => return Err(EINVAL), + }) + } + + /// Converts to a value compatible with the C code. + pub fn val(&self) -> u32 { + let (mut val, e) = match self { + Self::Low(e) => (bindings::CPUFREQ_RELATION_L, e), + Self::High(e) => (bindings::CPUFREQ_RELATION_H, e), + Self::Close(e) => (bindings::CPUFREQ_RELATION_C, e), + }; + + if *e { + val |= bindings::CPUFREQ_RELATION_E; + } + + val + } +} + +/// Equivalent to `struct cpufreq_policy_data` in the C code. +#[repr(transparent)] +pub struct PolicyData(*mut bindings::cpufreq_policy_data); + +impl PolicyData { + /// Creates new instance of [`PolicyData`]. + /// + /// # Safety + /// + /// Callers must ensure that `ptr` is valid and non-null. + pub unsafe fn from_ptr(ptr: *mut bindings::cpufreq_policy_data) -> Self { + Self(ptr) + } + + /// Returns the raw pointer to the C structure. + pub fn as_ptr(&self) -> *mut bindings::cpufreq_policy_data { + self.0 + } + + /// Provides a wrapper to the generic verify routine. + pub fn generic_verify(&self) -> Result<()> { + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to + // use it now. + to_result(unsafe { bindings::cpufreq_generic_frequency_table_verify(self.as_ptr()) }) + } +} + +/// Builder for the `struct cpufreq_frequency_table` in the C code. +#[repr(transparent)] +pub struct TableBuilder { + entries: Vec, +} + +impl TableBuilder { + /// Creates new instance of [`TableBuilder`]. + pub fn new() -> Self { + Self { + entries: Vec::new(), + } + } + + /// Adds a new entry to the table. + pub fn add(&mut self, frequency: u32, flags: u32, driver_data: u32) -> Result<()> { + // Adds new entry to the end of the vector. + Ok(self.entries.push( + bindings::cpufreq_frequency_table { + flags, + driver_data, + frequency, + }, + GFP_KERNEL, + )?) + } + + /// Creates [`Table`] from [`TableBuilder`]. + pub fn into_table(mut self) -> Result { + // Add last entry to the table. + self.add(bindings::CPUFREQ_TABLE_END as u32, 0, 0)?; + Table::from_builder(self.entries) + } +} + +/// A simple implementation of the cpufreq table, equivalent to the `struct +/// cpufreq_frequency_table` in the C code. +pub struct Table { + #[allow(dead_code)] + // Dynamically created table. + entries: Option>>, + + // Pointer to the statically or dynamically created table. + ptr: *mut bindings::cpufreq_frequency_table, + + // Number of entries in the table. + len: usize, +} + +impl Table { + /// Creates new instance of [`Table`] from [`TableBuilder`]. + fn from_builder(entries: Vec) -> Result { + let len = entries.len(); + if len == 0 { + return Err(EINVAL); + } + + // Pin the entries to memory, since we are passing its pointer to the C code. + let mut entries = Pin::new(entries); + + // The pointer is valid until the table gets dropped. + let ptr = entries.as_mut_ptr(); + + Ok(Self { + entries: Some(entries), + ptr, + // The last entry in table is reserved for `CPUFREQ_TABLE_END`. + len: len - 1, + }) + } + + /// Creates new instance of [`Table`] from raw pointer. + /// + /// # Safety + /// + /// Callers must ensure that `ptr` is valid and non-null for the lifetime of the [`Table`]. + pub unsafe fn from_raw(ptr: *mut bindings::cpufreq_frequency_table) -> Self { + Self { + entries: None, + ptr, + // SAFETY: The pointer is guaranteed to be valid for the lifetime of `Self`. + len: unsafe { bindings::cpufreq_table_len(ptr) } as usize, + } + } + + // Validate the index. + fn validate(&self, index: usize) -> Result<()> { + if index >= self.len { + Err(EINVAL) + } else { + Ok(()) + } + } + + /// Returns raw pointer to the `struct cpufreq_frequency_table` compatible with the C code. + pub fn as_ptr(&self) -> *mut bindings::cpufreq_frequency_table { + self.ptr + } + + /// Returns `frequency` at index in the [`Table`]. + pub fn freq(&self, index: usize) -> Result { + self.validate(index)?; + + // SAFETY: The pointer is guaranteed to be valid for the lifetime of `self` and `index` is + // also validated before this and is guaranteed to be within limits of the frequency table. + Ok(unsafe { (*self.ptr.add(index)).frequency }) + } + + /// Returns `flags` at index in the [`Table`]. + pub fn flags(&self, index: usize) -> Result { + self.validate(index)?; + + // SAFETY: The pointer is guaranteed to be valid for the lifetime of `self` and `index` is + // also validated before this and is guaranteed to be within limits of the frequency table. + Ok(unsafe { (*self.ptr.add(index)).flags }) + } + + /// Returns `data` at index in the [`Table`]. + pub fn data(&self, index: usize) -> Result { + self.validate(index)?; + + // SAFETY: The pointer is guaranteed to be valid for the lifetime of `self` and `index` is + // also validated before this and is guaranteed to be within limits of the frequency table. + Ok(unsafe { (*self.ptr.add(index)).driver_data }) + } +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 82b527c76017..7a3dcf1c3755 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -30,6 +30,8 @@ pub mod alloc; mod build_assert; pub mod clk; +#[cfg(CONFIG_CPU_FREQ)] +pub mod cpufreq; pub mod cpumask; pub mod device; pub mod devres;