From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sender4-pp-f112.zoho.com (sender4-pp-f112.zoho.com [136.143.188.112]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F1DCA379EF5; Fri, 24 Apr 2026 23:40:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.188.112 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777074023; cv=pass; b=OlT8AL45kwIEYBkXWLkmL+NNXpRYftfYgSh7n9ZfPb1U8EshqpI1eoVByYzawsMeyCW7P9XLTLlppnL9oWrVoZcLz8MkdL/0rQXK8xgm3PEdj8ohOmQ6vF4jsWEb3NMZBeBunyIA6miXcpTuMZX0dflDYCuC8afzQaWvIiTbLx4= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777074023; c=relaxed/simple; bh=Us2KrnXBRXPkm3Gy46S9wxzhbXrZpWEq7QojHZ2oB04=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=dQOOXKJYwS5IytrPxSpoHRVlTialqtHmhfJYXzoa9TyDDHthx7uh7D6BRP8ycSEwOP4eL5bnshu6+PwZcShwvDA8fy/PrsLIZNa8cCUaliDZsaeXMa/hQcZblA04Wr6LzAw8gucaMKYO8Ix+tFPZ/xQw4W9y/Abms+aCIIlir9M= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (1024-bit key) header.d=collabora.com header.i=deborah.brouwer@collabora.com header.b=BilPlTqx; arc=pass smtp.client-ip=136.143.188.112 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=collabora.com header.i=deborah.brouwer@collabora.com header.b="BilPlTqx" ARC-Seal: i=1; a=rsa-sha256; t=1777073979; cv=none; d=zohomail.com; s=zohoarc; b=bTWFR9b1Maajyig2bnrJDLyy1SRT1hr4JhYM9HFH2mSIoRf/uQspZXkJKWwGm8JL188H0M9Yb9u0Mh248EYkSg9xWh43LZP7KiJ6+qZMpBsQZYEmRC41n0R58OkYwdPqDCr8F2K1fTlFECDvsOEqXgDzzhg8jkt49rRRNgEFWTY= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1777073979; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=5104ZL/UD84fKWl1xO0y4+gtbwMaxDVZNsIrKYAj+HM=; b=eDLDJyARmsBy7sYYuQTOcHVlwCMrLhDMtDA4yNaWNMoWN5mkRSYpuCoV4jExTQ+Sfbmy2t3WYRy+AhHARzidn0QgEH2QRq+jZLPAIF8w2jjJNcvtoC+W1dVPmReev0WjcoCTA48jBm4JtBqaTdFgQ7Nn4ajPpJccgGNLkH/Etw0= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=deborah.brouwer@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1777073979; s=zohomail; d=collabora.com; i=deborah.brouwer@collabora.com; h=From:From:Date:Date:Subject:Subject:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-Id:Message-Id:References:In-Reply-To:To:To:Cc:Cc:Reply-To; bh=5104ZL/UD84fKWl1xO0y4+gtbwMaxDVZNsIrKYAj+HM=; b=BilPlTqxbM03rm4/ozAsqLwQtegkdFnDpIJPMJIVXri15ZGCdaCdU+SFriwpBaiN SzmkISTO7wGadThcGQgaHS5PVfHn8cj6wfKbPdfN0r7Wwi/8civHFNQmmxsDnoqYa3E GUKiZuZJzQmlryK8Jt2uUtdGqyFgIItLQt1i36eM= Received: by mx.zohomail.com with SMTPS id 17770739782601018.8985429837189; Fri, 24 Apr 2026 16:39:38 -0700 (PDT) From: Deborah Brouwer Date: Fri, 24 Apr 2026 16:39:13 -0700 Subject: [PATCH v4 19/20] rust: time: add arch_timer_get_rate wrapper Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260424-b4-fw-boot-v4-v4-19-a5d91050789d@collabora.com> References: <20260424-b4-fw-boot-v4-v4-0-a5d91050789d@collabora.com> In-Reply-To: <20260424-b4-fw-boot-v4-v4-0-a5d91050789d@collabora.com> To: Daniel Almeida , Alice Ryhl , Danilo Krummrich , David Airlie , Simona Vetter , Benno Lossin , Gary Guo , Miguel Ojeda , Boqun Feng , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Andreas Hindborg , Trevor Gross , FUJITA Tomonori , Frederic Weisbecker , Thomas Gleixner , Anna-Maria Behnsen , John Stultz , Stephen Boyd Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, boris.brezillon@collabora.com, beata.michalska@arm.com, lyude@redhat.com, acourbot@nvidia.com, work@onurozkan.dev, alvin.sun@linux.dev, Deborah Brouwer X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=1840; i=deborah.brouwer@collabora.com; h=from:subject:message-id; bh=Us2KrnXBRXPkm3Gy46S9wxzhbXrZpWEq7QojHZ2oB04=; b=owGbwMvMwCVWuULzOU9c7WvG02pJDJmv/ysUKf/2uyjym6PaT0Rzgdp5v9gfbuWz/adfeDxXL CUu0lW2o5SFQYyLQVZMkeWsvVGPeNV7I935/5th5rAygQxh4OIUgIlcVGdkeHHf0FZgTmlO/alY NYfkd36Pp4ttc/kQ4KK43kB8bkirLSPD7Qebbtk1ZnWePrpM+eksJvGELi8+JlvxUi+tXvbPe17 wAwA= X-Developer-Key: i=deborah.brouwer@collabora.com; a=openpgp; fpr=CD3F328C177AEF322D9FFF8379A829E70C5E7DEB Provide a safe Rust wrapper for arch_timer_get_rate(). The underlying C helper returns 0 when the ARM architectural timer is not available or not yet initialized. Map this to Option to make the absence of a valid rate explicit to Rust callers. This allows Rust drivers to query the system timer frequency and select appropriate time sources when programming hardware timeouts. Signed-off-by: Deborah Brouwer --- rust/kernel/time.rs | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs index 6ea98dfcd027..03ce96450fc8 100644 --- a/rust/kernel/time.rs +++ b/rust/kernel/time.rs @@ -359,6 +359,35 @@ fn div(self, rhs: Self) -> Self::Output { } } +/// Returns the ARM architecture timer frequency in Hz, if available. +/// +/// This function queries the system-wide ARM architecture timer frequency. +/// The architecture timer provides a consistent time source across all CPU cores. +/// +/// Returns `None` if: +/// - The ARM architecture timer is not available (`CONFIG_ARM_ARCH_TIMER` not enabled) +/// - The timer rate is zero (not initialized) +/// +/// # Examples +/// +/// ``` +/// use kernel::time::arch_timer_get_rate; +/// +/// if let Some(rate) = arch_timer_get_rate() { +/// // Use `rate`. +/// } +/// ``` +pub fn arch_timer_get_rate() -> Option { + // SAFETY: The C API is available in all configs; when CONFIG_ARM_ARCH_TIMER + // is disabled, the header provides a stub returning 0. + let rate = unsafe { bindings::arch_timer_get_rate() }; + if rate == 0 { + None + } else { + Some(rate) + } +} + impl Delta { /// A span of time equal to zero. pub const ZERO: Self = Self { nanos: 0 }; -- 2.53.0