Commit e2ef1675 authored by Peter Hilber's avatar Peter Hilber Committed by Michael S. Tsirkin
Browse files

virtio_rtc: Add Arm Generic Timer cross-timestamping 



For platforms using the Arm Generic Timer, add precise cross-timestamping
support to virtio_rtc.

Always report the CP15 virtual counter as the HW counter in use by
arm_arch_timer, since the Linux kernel's usage of the Arm Generic Timer
should always be compatible with this.

Signed-off-by: default avatarPeter Hilber <quic_philber@quicinc.com>
Message-Id: <20250509160734.1772-4-quic_philber@quicinc.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 9a17125a

drivers/virtio/Kconfig

+13 −0
Original line number Diff line number Diff line
@@ -221,6 +221,19 @@ config VIRTIO_RTC_PTP 


	 If unsure, say Y.



config VIRTIO_RTC_ARM

	bool "Virtio RTC cross-timestamping using Arm Generic Timer"

	default y

	depends on VIRTIO_RTC_PTP && ARM_ARCH_TIMER

	help

	 This enables Virtio RTC cross-timestamping using the Arm Generic Timer.

	 It only has an effect if the Virtio RTC device also supports this. The

	 cross-timestamp is available through the PTP clock driver precise

	 cross-timestamp ioctl (PTP_SYS_OFFSET_PRECISE2 aka

	 PTP_SYS_OFFSET_PRECISE).



	 If unsure, say Y.



endif # VIRTIO_RTC



endif # VIRTIO_MENU

drivers/virtio/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -17,3 +17,4 @@ obj-$(CONFIG_VIRTIO_DEBUG) += virtio_debug.o 
obj-$(CONFIG_VIRTIO_RTC) += virtio_rtc.o

virtio_rtc-y := virtio_rtc_driver.o

virtio_rtc-$(CONFIG_VIRTIO_RTC_PTP) += virtio_rtc_ptp.o

virtio_rtc-$(CONFIG_VIRTIO_RTC_ARM) += virtio_rtc_arm.o

drivers/virtio/virtio_rtc_arm.c

0 → 100644
+23 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-or-later

/*

 * Provides cross-timestamp params for Arm.

 *

 * Copyright (C) 2022-2023 OpenSynergy GmbH

 * Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved.

 */



#include <linux/clocksource_ids.h>



#include <uapi/linux/virtio_rtc.h>



#include "virtio_rtc_internal.h"



/* see header for doc */



int viortc_hw_xtstamp_params(u8 *hw_counter, enum clocksource_ids *cs_id)

{

	*hw_counter = VIRTIO_RTC_COUNTER_ARM_VCT;

	*cs_id = CSID_ARM_ARCH_COUNTER;



	return 0;

}