linux-kernel - [PATCH] Various improvements on clock abstractions

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Message-ID: <20250616200103.24245-1-work@onurozkan.dev>
Date: Mon, 16 Jun 2025 23:01:03 +0300
From: onur-ozkan <work@...rozkan.dev>
To: linux-clk@...r.kernel.org,
	rust-for-linux@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: mturquette@...libre.com,
	sboyd@...nel.org,
	ojeda@...nel.org,
	alex.gaynor@...il.com,
	boqun.feng@...il.com,
	gary@...yguo.net,
	bjorn3_gh@...tonmail.com,
	lossin@...nel.org,
	a.hindborg@...nel.org,
	aliceryhl@...gle.com,
	tmgross@...ch.edu,
	dakr@...nel.org,
	onur-ozkan <work@...rozkan.dev>
Subject: [PATCH] Various improvements on clock abstractions

A few changes to improve the clock abstractions and make them a little
more idiomatic:

1. `impl Hertz` functions are now constant and compile-time evaluable.
2. `Hertz` conversions are now done with constant variables, which should
    make them more readable.
3. `con_id` is handled in a single line using `map_or` instead of using
    nested if-else blocks.

Signed-off-by: onur-ozkan <work@...rozkan.dev>
---
 rust/kernel/clk.rs | 42 +++++++++++++++++++-----------------------
 1 file changed, 19 insertions(+), 23 deletions(-)

diff --git a/rust/kernel/clk.rs b/rust/kernel/clk.rs
index 6041c6d07527..fbcea31dbcca 100644
--- a/rust/kernel/clk.rs
+++ b/rust/kernel/clk.rs
@@ -30,39 +30,43 @@
 pub struct Hertz(pub c_ulong);
 
 impl Hertz {
+    const KHZ_TO_HZ: c_ulong = 1_000;
+    const MHZ_TO_HZ: c_ulong = 1_000_000;
+    const GHZ_TO_HZ: c_ulong = 1_000_000_000;
+
     /// Create a new instance from kilohertz (kHz)
-    pub fn from_khz(khz: c_ulong) -> Self {
-        Self(khz * 1_000)
+    pub const fn from_khz(khz: c_ulong) -> Self {
+        Self(khz * Self::KHZ_TO_HZ)
     }
 
     /// Create a new instance from megahertz (MHz)
-    pub fn from_mhz(mhz: c_ulong) -> Self {
-        Self(mhz * 1_000_000)
+    pub const fn from_mhz(mhz: c_ulong) -> Self {
+        Self(mhz * Self::MHZ_TO_HZ)
     }
 
     /// Create a new instance from gigahertz (GHz)
-    pub fn from_ghz(ghz: c_ulong) -> Self {
-        Self(ghz * 1_000_000_000)
+    pub const fn from_ghz(ghz: c_ulong) -> Self {
+        Self(ghz * Self::GHZ_TO_HZ)
     }
 
     /// Get the frequency in hertz
-    pub fn as_hz(&self) -> c_ulong {
+    pub const fn as_hz(&self) -> c_ulong {
         self.0
     }
 
     /// Get the frequency in kilohertz
-    pub fn as_khz(&self) -> c_ulong {
-        self.0 / 1_000
+    pub const fn as_khz(&self) -> c_ulong {
+        self.0 / Self::KHZ_TO_HZ
     }
 
     /// Get the frequency in megahertz
-    pub fn as_mhz(&self) -> c_ulong {
-        self.0 / 1_000_000
+    pub const fn as_mhz(&self) -> c_ulong {
+        self.0 / Self::MHZ_TO_HZ
     }
 
     /// Get the frequency in gigahertz
-    pub fn as_ghz(&self) -> c_ulong {
-        self.0 / 1_000_000_000
+    pub const fn as_ghz(&self) -> c_ulong {
+        self.0 / Self::GHZ_TO_HZ
     }
 }
 
@@ -132,11 +136,7 @@ impl Clk {
         ///
         /// [`clk_get`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_get
         pub fn get(dev: &Device, name: Option<&CStr>) -> Result<Self> {
-            let con_id = if let Some(name) = name {
-                name.as_ptr()
-            } else {
-                ptr::null()
-            };
+            let con_id = name.map_or(ptr::null(), |n| n.as_ptr());
 
             // SAFETY: It is safe to call [`clk_get`] for a valid device pointer.
             //
@@ -304,11 +304,7 @@ impl OptionalClk {
         /// [`clk_get_optional`]:
         /// https://docs.kernel.org/core-api/kernel-api.html#c.clk_get_optional
         pub fn get(dev: &Device, name: Option<&CStr>) -> Result<Self> {
-            let con_id = if let Some(name) = name {
-                name.as_ptr()
-            } else {
-                ptr::null()
-            };
+            let con_id = name.map_or(ptr::null(), |n| n.as_ptr());
 
             // SAFETY: It is safe to call [`clk_get_optional`] for a valid device pointer.
             //
-- 
2.49.0