linux-kernel - [PATCH V6 04/15] rust: device: Add few helpers

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Message-Id: <429b7539f787ad360cd28fd1db6dc3d6c1fe289d.1736248242.git.viresh.kumar@linaro.org>
Date: Tue,  7 Jan 2025 16:51:37 +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>,
	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>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Danilo Krummrich <dakr@...nel.org>
Cc: Viresh Kumar <viresh.kumar@...aro.org>,
	linux-pm@...r.kernel.org,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Stephen Boyd <sboyd@...nel.org>,
	Nishanth Menon <nm@...com>,
	rust-for-linux@...r.kernel.org,
	Manos Pitsidianakis <manos.pitsidianakis@...aro.org>,
	Erik Schilling <erik.schilling@...aro.org>,
	Alex Bennée <alex.bennee@...aro.org>,
	Joakim Bech <joakim.bech@...aro.org>,
	Rob Herring <robh@...nel.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH V6 04/15] rust: device: Add few helpers

Add from_cpu() and property_present() helpers to the device bindings.

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 rust/bindings/bindings_helper.h |  1 +
 rust/kernel/device.rs           | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 43f5c381aab0..70e4b7b0f638 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -31,6 +31,7 @@
 #include <linux/pid_namespace.h>
 #include <linux/platform_device.h>
 #include <linux/poll.h>
+#include <linux/property.h>
 #include <linux/refcount.h>
 #include <linux/sched.h>
 #include <linux/security.h>
diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index d5e6a19ff6b7..5bfbc4bdfadc 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -6,6 +6,9 @@
 
 use crate::{
     bindings,
+    error::Result,
+    prelude::ENODEV,
+    str::CString,
     types::{ARef, Opaque},
 };
 use core::{fmt, ptr};
@@ -59,6 +62,18 @@ pub unsafe fn get_device(ptr: *mut bindings::device) -> ARef<Self> {
         unsafe { Self::as_ref(ptr) }.into()
     }
 
+    /// Creates a new ref-counted instance of device of a CPU.
+    pub fn from_cpu(cpu: u32) -> Result<ARef<Self>> {
+        // SAFETY: It is safe to call `get_cpu_device()` for any CPU number.
+        let ptr = unsafe { bindings::get_cpu_device(cpu) };
+        if ptr.is_null() {
+            return Err(ENODEV);
+        }
+
+        // SAFETY: By the safety requirements, ptr is valid.
+        Ok(unsafe { Device::get_device(ptr) })
+    }
+
     /// Obtain the raw `struct device *`.
     pub(crate) fn as_raw(&self) -> *mut bindings::device {
         self.0.get()
@@ -180,6 +195,12 @@ unsafe fn printk(&self, klevel: &[u8], msg: fmt::Arguments<'_>) {
             )
         };
     }
+
+    /// Checks if property is present or not.
+    pub fn property_present(&self, name: &CString) -> bool {
+        // SAFETY: `name` is null-terminated. `self.as_raw` is valid because `self` is valid.
+        unsafe { bindings::device_property_present(self.as_raw(), name.as_ptr() as *const _) }
+    }
 }
 
 // SAFETY: Instances of `Device` are always reference-counted.
-- 
2.31.1.272.g89b43f80a514