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Subject: [RFC PATCH 7/7] virtio_rtc: Add Arm Generic Timer cross-timestamping
Add PTP_SYS_OFFSET_PRECISE2 support on platforms using the Arm Generic Timer, by forwarding the clocksource information from arm_arch_timer. Support only the CP15 counter interfaces, since the memory-mapped interfaces are not supported by the Virtio RTC draft spec [1]. [1] https://lists.oasis-open.org/archives/virtio-comment/202306/msg00592.html Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com> --- drivers/virtio/Kconfig | 13 ++++++++++ drivers/virtio/Makefile | 1 + drivers/virtio/virtio_rtc_arm.c | 44 +++++++++++++++++++++++++++++++++ 3 files changed, 58 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..2367f054081c --- /dev/null +++ b/drivers/virtio/virtio_rtc_arm.c @@ -0,0 +1,44 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Provides cross-timestamp params for Arm. + * + * Copyright (C) 2022-2023 OpenSynergy GmbH + */ + +#include <clocksource/arm_arch_timer.h> +#include <linux/err.h> + +#include <uapi/linux/virtio_rtc.h> + +#include "virtio_rtc_internal.h" + +static const u16 viortc_hw_counters[] = { VIRTIO_RTC_COUNTER_ARM_VIRT, + VIRTIO_RTC_COUNTER_ARM_PHYS }; + +/* see header for doc */ +int viortc_hw_get_counters(const u16 **hw_counters, int *num_hw_counters) +{ + *hw_counters = viortc_hw_counters; + *num_hw_counters = ARRAY_SIZE(viortc_hw_counters); + + return 0; +} + +/* see header for doc */ +int viortc_hw_xtstamp_params(u16 *hw_counter, struct clocksource **cs) +{ + *cs = arch_timer_get_cs(); + + switch (arch_timer_counter_get_type()) { + case ARCH_COUNTER_CP15_VIRT: + *hw_counter = VIRTIO_RTC_COUNTER_ARM_VIRT; + break; + case ARCH_COUNTER_CP15_PHYS: + *hw_counter = VIRTIO_RTC_COUNTER_ARM_PHYS; + break; + default: + return -EINVAL; + } + + return 0; +} -- 2.39.2
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