linux-kernel - [PATCH V11 14/15] rust: opp: Extend OPP abstractions with cpufreq support

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Message-Id: <a61540db4633389016e8a885c7f6e3cc117d04ec.1745218976.git.viresh.kumar@linaro.org>
Date: Mon, 21 Apr 2025 12:52:21 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: "Rafael J. Wysocki" <rafael@...nel.org>,
	Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
	Danilo Krummrich <dakr@...hat.com>,
	Viresh Kumar <vireshk@...nel.org>,
	Nishanth Menon <nm@...com>,
	Stephen Boyd <sboyd@...nel.org>,
	Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <benno.lossin@...ton.me>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Trevor Gross <tmgross@...ch.edu>,
	Danilo Krummrich <dakr@...nel.org>
Cc: Viresh Kumar <viresh.kumar@...aro.org>,
	linux-pm@...r.kernel.org,
	Vincent Guittot <vincent.guittot@...aro.org>,
	rust-for-linux@...r.kernel.org,
	Manos Pitsidianakis <manos.pitsidianakis@...aro.org>,
	Alex Bennée <alex.bennee@...aro.org>,
	Joakim Bech <joakim.bech@...aro.org>,
	Rob Herring <robh@...nel.org>,
	Yury Norov <yury.norov@...il.com>,
	Burak Emir <bqe@...gle.com>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Russell King <linux@...linux.org.uk>,
	linux-clk@...r.kernel.org,
	Michael Turquette <mturquette@...libre.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH V11 14/15] rust: opp: Extend OPP abstractions with cpufreq support

Extend the OPP abstractions to include support for interacting with the
cpufreq core, including the ability to retrieve frequency tables from
OPP table.

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 rust/kernel/opp.rs | 70 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs
index 8b61ea8748a3..985d90dc0671 100644
--- a/rust/kernel/opp.rs
+++ b/rust/kernel/opp.rs
@@ -19,6 +19,69 @@
     types::{ARef, AlwaysRefCounted, Opaque},
 };
 
+#[cfg(CONFIG_CPU_FREQ)]
+/// Frequency table implementation.
+mod freq {
+    use super::*;
+    use crate::cpufreq;
+    use core::ops::Deref;
+
+    /// OPP frequency table.
+    ///
+    /// A [`cpufreq::Table`] created from [`Table`].
+    pub struct FreqTable {
+        dev: ARef<Device>,
+        ptr: *mut bindings::cpufreq_frequency_table,
+    }
+
+    impl FreqTable {
+        /// Creates a new instance of [`FreqTable`] from [`Table`].
+        pub(crate) fn new(table: &Table) -> Result<Self> {
+            let mut ptr: *mut bindings::cpufreq_frequency_table = ptr::null_mut();
+
+            // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+            // requirements.
+            to_result(unsafe {
+                bindings::dev_pm_opp_init_cpufreq_table(table.dev.as_raw(), &mut ptr)
+            })?;
+
+            Ok(Self {
+                dev: table.dev.clone(),
+                ptr,
+            })
+        }
+
+        /// Returns a reference to the underlying [`cpufreq::Table`].
+        #[inline]
+        fn table(&self) -> &cpufreq::Table {
+            // SAFETY: The `ptr` is guaranteed by the C code to be valid.
+            unsafe { cpufreq::Table::from_raw(self.ptr) }
+        }
+    }
+
+    impl Deref for FreqTable {
+        type Target = cpufreq::Table;
+
+        #[inline]
+        fn deref(&self) -> &Self::Target {
+            self.table()
+        }
+    }
+
+    impl Drop for FreqTable {
+        fn drop(&mut self) {
+            // SAFETY: The pointer was created via `dev_pm_opp_init_cpufreq_table`, and is only
+            // freed here.
+            unsafe {
+                bindings::dev_pm_opp_free_cpufreq_table(self.dev.as_raw(), &mut self.as_raw())
+            };
+        }
+    }
+}
+
+#[cfg(CONFIG_CPU_FREQ)]
+pub use freq::FreqTable;
+
 use core::{marker::PhantomData, ptr};
 
 use macros::vtable;
@@ -751,6 +814,13 @@ pub fn adjust_voltage(
         })
     }
 
+    /// Creates [`FreqTable`] from [`Table`].
+    #[cfg(CONFIG_CPU_FREQ)]
+    #[inline]
+    pub fn cpufreq_table(&mut self) -> Result<FreqTable> {
+        FreqTable::new(self)
+    }
+
     /// Configures device with [`OPP`] matching the frequency value.
     #[inline]
     pub fn set_rate(&self, freq: Hertz) -> Result<()> {
-- 
2.31.1.272.g89b43f80a514