[RFC PATCH v2 6/6] virtio_rtc: Add Arm Generic Timer cross-timestamping
From: Peter Hilber <hidden>
Date: 2023-08-18 01:21:14
Also in:
lkml
Subsystem:
the rest, virtio core, virtio rtc driver · Maintainers:
Linus Torvalds, "Michael S. Tsirkin", Jason Wang, Peter Hilber
Add PTP_SYS_OFFSET_PRECISE2 support on platforms using the Arm Generic
Timer.
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: Peter Hilber <redacted>
---
Notes:
v2:
- Depend on prerequisite patch series "treewide: Use clocksource id for
get_device_system_crosststamp()".
- Return clocksource id instead of calling dropped arm_arch_timer helpers.
- Always report the CP15 virtual counter to be in use by arm_arch_timer,
since distinction of Arm physical and virtual counter appears unneeded
after discussion with Marc Zyngier.
drivers/virtio/Kconfig | 13 +++++++++++++
drivers/virtio/Makefile | 1 +
drivers/virtio/virtio_rtc_arm.c | 22 ++++++++++++++++++++++
3 files changed, 36 insertions(+)
create mode 100644 drivers/virtio/virtio_rtc_arm.c
diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 7369ecd7dd01..ed3f541032a0 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig@@ -203,4 +203,17 @@ 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 or + PTP_SYS_OFFSET_PRECISE). + + If unsure, say Y. + endif # VIRTIO_MENU
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
index 4d48cbcae6bb..781dff9f8822 100644
--- a/drivers/virtio/Makefile
+++ b/drivers/virtio/Makefile@@ -15,3 +15,4 @@ obj-$(CONFIG_VIRTIO_DMA_SHARED_BUFFER) += virtio_dma_buf.o obj-$(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
diff --git a/drivers/virtio/virtio_rtc_arm.c b/drivers/virtio/virtio_rtc_arm.c
new file mode 100644
index 000000000000..5185b130b3f1
--- /dev/null
+++ b/drivers/virtio/virtio_rtc_arm.c@@ -0,0 +1,22 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Provides cross-timestamp params for Arm. + * + * Copyright (C) 2022-2023 OpenSynergy GmbH + */ + +#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(u16 *hw_counter, enum clocksource_ids *cs_id) +{ + *hw_counter = VIRTIO_RTC_COUNTER_ARM_VIRT; + *cs_id = CSID_ARM_ARCH_COUNTER; + + return 0; +}
--
2.39.2
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