drivers/virtio/virtio_rtc_ptp.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Expose virtio_rtc clocks as PTP clocks.
  *
  * Copyright (C) 2022-2023 OpenSynergy GmbH
  * Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved.
  *
  * Derived from ptp_kvm_common.c, virtual PTP 1588 clock for use with KVM
  * guests.
  *
  * Copyright (C) 2017 Red Hat Inc.
  */

 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/ptp_clock_kernel.h>

 #include <uapi/linux/virtio_rtc.h>

 #include "virtio_rtc_internal.h"

 /**
  * struct viortc_ptp_clock - PTP clock abstraction
  * @ptp_clock: PTP clock handle for unregistering
  * @viortc: virtio_rtc device data
  * @ptp_info: PTP clock description
  * @vio_clk_id: virtio_rtc clock id
  * @have_cross: device supports crosststamp with available HW counter
  */
 struct viortc_ptp_clock {
 	struct ptp_clock *ptp_clock;
 	struct viortc_dev *viortc;
 	struct ptp_clock_info ptp_info;
 	u16 vio_clk_id;
 	bool have_cross;
 };

 /**
  * struct viortc_ptp_cross_ctx - context for get_device_system_crosststamp()
  * @device_time: device clock reading
  * @system_counterval: HW counter value at device_time
  *
  * Provides the already obtained crosststamp to get_device_system_crosststamp().
  */
 struct viortc_ptp_cross_ctx {
 	ktime_t device_time;
 	struct system_counterval_t system_counterval;
 };

 /* Weak function in case get_device_system_crosststamp() is not supported */
 int __weak viortc_hw_xtstamp_params(u8 *hw_counter, enum clocksource_ids *cs_id)
 {
 	return -EOPNOTSUPP;
 }

 /**
  * viortc_ptp_get_time_fn() - callback for get_device_system_crosststamp()
  * @device_time: device clock reading
  * @system_counterval: HW counter value at device_time
  * @ctx: context with already obtained crosststamp
  *
  * Return: zero (success).
  */
 static int viortc_ptp_get_time_fn(ktime_t *device_time,
 				  struct system_counterval_t *system_counterval,
 				  void *ctx)
 {
 	struct viortc_ptp_cross_ctx *vio_ctx = ctx;

 	*device_time = vio_ctx->device_time;
 	*system_counterval = vio_ctx->system_counterval;

 	return 0;
 }

 /**
  * viortc_ptp_do_xtstamp() - get crosststamp from device
  * @vio_ptp: virtio_rtc PTP clock
  * @hw_counter: virtio_rtc HW counter type
  * @cs_id: clocksource id corresponding to hw_counter
  * @ctx: context for get_device_system_crosststamp()
  *
  * Reads HW-specific crosststamp from device.
  *
  * Context: Process context.
  * Return: Zero on success, negative error code otherwise.
  */
 static int viortc_ptp_do_xtstamp(struct viortc_ptp_clock *vio_ptp,
 				 u8 hw_counter, enum clocksource_ids cs_id,
 				 struct viortc_ptp_cross_ctx *ctx)
 {
 	u64 max_ns, ns;
 	int ret;

 	ctx->system_counterval.cs_id = cs_id;

 	ret = viortc_read_cross(vio_ptp->viortc, vio_ptp->vio_clk_id,
 				hw_counter, &ns,
 				&ctx->system_counterval.cycles);
 	if (ret)
 		return ret;

 	max_ns = (u64)ktime_to_ns(KTIME_MAX);
 	if (ns > max_ns)
 		return -EINVAL;

 	ctx->device_time = ns_to_ktime(ns);

 	return 0;
 }

 /*
  * PTP clock operations
  */

 /**
  * viortc_ptp_getcrosststamp() - PTP clock getcrosststamp op
  * @ptp: PTP clock info
  * @xtstamp: crosststamp
  *
  * Context: Process context.
  * Return: Zero on success, negative error code otherwise.
  */
 static int viortc_ptp_getcrosststamp(struct ptp_clock_info *ptp,
 				     struct system_device_crosststamp *xtstamp)
 {
 	struct viortc_ptp_clock *vio_ptp =
 		container_of(ptp, struct viortc_ptp_clock, ptp_info);
 	struct system_time_snapshot history_begin;
 	struct viortc_ptp_cross_ctx ctx;
 	enum clocksource_ids cs_id;
 	u8 hw_counter;
 	int ret;

 	if (!vio_ptp->have_cross)
 		return -EOPNOTSUPP;

 	ret = viortc_hw_xtstamp_params(&hw_counter, &cs_id);
 	if (ret)
 		return ret;

 	ktime_get_snapshot(&history_begin);
 	if (history_begin.cs_id != cs_id)
 		return -EOPNOTSUPP;

 	/*
 	 * Getting the timestamp can take many milliseconds with a slow Virtio
 	 * device. This is too long for viortc_ptp_get_time_fn() passed to
 	 * get_device_system_crosststamp(), which has to usually return before
 	 * the timekeeper seqcount increases (every tick or so).
 	 *
 	 * So, get the actual cross-timestamp first.
 	 */
 	ret = viortc_ptp_do_xtstamp(vio_ptp, hw_counter, cs_id, &ctx);
 	if (ret)
 		return ret;

 	ret = get_device_system_crosststamp(viortc_ptp_get_time_fn, &ctx,
 					    &history_begin, xtstamp);
 	if (ret)
 		pr_debug("%s: get_device_system_crosststamp() returned %d\n",
 			 __func__, ret);

 	return ret;
 }

 /* viortc_ptp_adjfine() - unsupported PTP clock adjfine op */
 static int viortc_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
 {
 	return -EOPNOTSUPP;
 }

 /* viortc_ptp_adjtime() - unsupported PTP clock adjtime op */
 static int viortc_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
 {
 	return -EOPNOTSUPP;
 }

 /* viortc_ptp_settime64() - unsupported PTP clock settime64 op */
 static int viortc_ptp_settime64(struct ptp_clock_info *ptp,
 				const struct timespec64 *ts)
 {
 	return -EOPNOTSUPP;
 }

 /*
  * viortc_ptp_gettimex64() - PTP clock gettimex64 op
  *
  * Context: Process context.
  */
 static int viortc_ptp_gettimex64(struct ptp_clock_info *ptp,
 				 struct timespec64 *ts,
 				 struct ptp_system_timestamp *sts)
 {
 	struct viortc_ptp_clock *vio_ptp =
 		container_of(ptp, struct viortc_ptp_clock, ptp_info);
 	int ret;
 	u64 ns;

 	ptp_read_system_prets(sts);
 	ret = viortc_read(vio_ptp->viortc, vio_ptp->vio_clk_id, &ns);
 	ptp_read_system_postts(sts);

 	if (ret)
 		return ret;

 	if (ns > (u64)S64_MAX)
 		return -EINVAL;

 	*ts = ns_to_timespec64((s64)ns);

 	return 0;
 }

 /* viortc_ptp_enable() - unsupported PTP clock enable op */
 static int viortc_ptp_enable(struct ptp_clock_info *ptp,
 			     struct ptp_clock_request *rq, int on)
 {
 	return -EOPNOTSUPP;
 }

 /*
  * viortc_ptp_info_template - ptp_clock_info template
  *
  * The .name member will be set for individual virtio_rtc PTP clocks.
  *
  * The .getcrosststamp member will be cleared for PTP clocks not supporting
  * crosststamp.
  */
 static const struct ptp_clock_info viortc_ptp_info_template = {
 	.owner = THIS_MODULE,
 	/* .name is set according to clock type */
 	.adjfine = viortc_ptp_adjfine,
 	.adjtime = viortc_ptp_adjtime,
 	.gettimex64 = viortc_ptp_gettimex64,
 	.settime64 = viortc_ptp_settime64,
 	.enable = viortc_ptp_enable,
 	.getcrosststamp = viortc_ptp_getcrosststamp,
 };

 /**
  * viortc_ptp_unregister() - PTP clock unregistering wrapper
  * @vio_ptp: virtio_rtc PTP clock
  * @parent_dev: parent device of PTP clock
  *
  * Return: Zero on success, negative error code otherwise.
  */
 int viortc_ptp_unregister(struct viortc_ptp_clock *vio_ptp,
 			  struct device *parent_dev)
 {
 	int ret = ptp_clock_unregister(vio_ptp->ptp_clock);

 	if (!ret)
 		devm_kfree(parent_dev, vio_ptp);

 	return ret;
 }

 /**
  * viortc_ptp_get_cross_cap() - get xtstamp support info from device
  * @viortc: virtio_rtc device data
  * @vio_ptp: virtio_rtc PTP clock abstraction
  *
  * Context: Process context.
  * Return: Zero on success, negative error code otherwise.
  */
 static int viortc_ptp_get_cross_cap(struct viortc_dev *viortc,
 				    struct viortc_ptp_clock *vio_ptp)
 {
 	enum clocksource_ids cs_id;
 	bool xtstamp_supported;
 	u8 hw_counter;
 	int ret;

 	ret = viortc_hw_xtstamp_params(&hw_counter, &cs_id);
 	if (ret) {
 		vio_ptp->have_cross = false;
 		return 0;
 	}

 	ret = viortc_cross_cap(viortc, vio_ptp->vio_clk_id, hw_counter,
 			       &xtstamp_supported);
 	if (ret)
 		return ret;

 	vio_ptp->have_cross = xtstamp_supported;

 	return 0;
 }

 /**
  * viortc_ptp_register() - prepare and register PTP clock
  * @viortc: virtio_rtc device data
  * @parent_dev: parent device for PTP clock
  * @vio_clk_id: id of virtio_rtc clock which backs PTP clock
  * @ptp_clock_name: PTP clock name
  *
  * Context: Process context.
  * Return: Pointer on success, ERR_PTR() otherwise; NULL if PTP clock support
  *         not available.
  */
 struct viortc_ptp_clock *viortc_ptp_register(struct viortc_dev *viortc,
 					     struct device *parent_dev,
 					     u16 vio_clk_id,
 					     const char *ptp_clock_name)
 {
 	struct viortc_ptp_clock *vio_ptp;
 	struct ptp_clock *ptp_clock;
 	ssize_t len;
 	int ret;

 	vio_ptp = devm_kzalloc(parent_dev, sizeof(*vio_ptp), GFP_KERNEL);
 	if (!vio_ptp)
 		return ERR_PTR(-ENOMEM);

 	vio_ptp->viortc = viortc;
 	vio_ptp->vio_clk_id = vio_clk_id;
 	vio_ptp->ptp_info = viortc_ptp_info_template;
 	len = strscpy(vio_ptp->ptp_info.name, ptp_clock_name,
 		      sizeof(vio_ptp->ptp_info.name));
 	if (len < 0) {
 		ret = len;
 		goto err_free_dev;
 	}

 	ret = viortc_ptp_get_cross_cap(viortc, vio_ptp);
 	if (ret)
 		goto err_free_dev;

 	if (!vio_ptp->have_cross)
 		vio_ptp->ptp_info.getcrosststamp = NULL;

 	ptp_clock = ptp_clock_register(&vio_ptp->ptp_info, parent_dev);
 	if (IS_ERR(ptp_clock))
 		goto err_on_register;

 	vio_ptp->ptp_clock = ptp_clock;

 	return vio_ptp;

 err_on_register:
 	ret = PTR_ERR(ptp_clock);

 err_free_dev:
 	devm_kfree(parent_dev, vio_ptp);
 	return ERR_PTR(ret);
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Expose virtio_rtc clocks as PTP clocks.
	*
	* Copyright (C) 2022-2023 OpenSynergy GmbH
	* Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved.
	*
	* Derived from ptp_kvm_common.c, virtual PTP 1588 clock for use with KVM
	* guests.
	*
	* Copyright (C) 2017 Red Hat Inc.
	*/

	#include <linux/device.h>
	#include <linux/err.h>
	#include <linux/ptp_clock_kernel.h>

	#include <uapi/linux/virtio_rtc.h>

	#include "virtio_rtc_internal.h"

	/**
	* struct viortc_ptp_clock - PTP clock abstraction
	* @ptp_clock: PTP clock handle for unregistering
	* @viortc: virtio_rtc device data
	* @ptp_info: PTP clock description
	* @vio_clk_id: virtio_rtc clock id
	* @have_cross: device supports crosststamp with available HW counter
	*/
	struct viortc_ptp_clock {
	struct ptp_clock *ptp_clock;
	struct viortc_dev *viortc;
	struct ptp_clock_info ptp_info;
	u16 vio_clk_id;
	bool have_cross;
	};

	/**
	* struct viortc_ptp_cross_ctx - context for get_device_system_crosststamp()
	* @device_time: device clock reading
	* @system_counterval: HW counter value at device_time
	*
	* Provides the already obtained crosststamp to get_device_system_crosststamp().
	*/
	struct viortc_ptp_cross_ctx {
	ktime_t device_time;
	struct system_counterval_t system_counterval;
	};

	/* Weak function in case get_device_system_crosststamp() is not supported */
	int __weak viortc_hw_xtstamp_params(u8 hw_counter, enum clocksource_ids cs_id)
	{
	return -EOPNOTSUPP;
	}

	/**
	* viortc_ptp_get_time_fn() - callback for get_device_system_crosststamp()
	* @device_time: device clock reading
	* @system_counterval: HW counter value at device_time
	* @ctx: context with already obtained crosststamp
	*
	* Return: zero (success).
	*/
	static int viortc_ptp_get_time_fn(ktime_t *device_time,
	struct system_counterval_t *system_counterval,
	void *ctx)
	{
	struct viortc_ptp_cross_ctx *vio_ctx = ctx;

	*device_time = vio_ctx->device_time;
	*system_counterval = vio_ctx->system_counterval;

	return 0;
	}

	/**
	* viortc_ptp_do_xtstamp() - get crosststamp from device
	* @vio_ptp: virtio_rtc PTP clock
	* @hw_counter: virtio_rtc HW counter type
	* @cs_id: clocksource id corresponding to hw_counter
	* @ctx: context for get_device_system_crosststamp()
	*
	* Reads HW-specific crosststamp from device.
	*
	* Context: Process context.
	* Return: Zero on success, negative error code otherwise.
	*/
	static int viortc_ptp_do_xtstamp(struct viortc_ptp_clock *vio_ptp,
	u8 hw_counter, enum clocksource_ids cs_id,
	struct viortc_ptp_cross_ctx *ctx)
	{
	u64 max_ns, ns;
	int ret;

	ctx->system_counterval.cs_id = cs_id;

	ret = viortc_read_cross(vio_ptp->viortc, vio_ptp->vio_clk_id,
	hw_counter, &ns,
	&ctx->system_counterval.cycles);
	if (ret)
	return ret;

	max_ns = (u64)ktime_to_ns(KTIME_MAX);
	if (ns > max_ns)
	return -EINVAL;

	ctx->device_time = ns_to_ktime(ns);

	return 0;
	}

	/*
	* PTP clock operations
	*/

	/**
	* viortc_ptp_getcrosststamp() - PTP clock getcrosststamp op
	* @ptp: PTP clock info
	* @xtstamp: crosststamp
	*
	* Context: Process context.
	* Return: Zero on success, negative error code otherwise.
	*/
	static int viortc_ptp_getcrosststamp(struct ptp_clock_info *ptp,
	struct system_device_crosststamp *xtstamp)
	{
	struct viortc_ptp_clock *vio_ptp =
	container_of(ptp, struct viortc_ptp_clock, ptp_info);
	struct system_time_snapshot history_begin;
	struct viortc_ptp_cross_ctx ctx;
	enum clocksource_ids cs_id;
	u8 hw_counter;
	int ret;

	if (!vio_ptp->have_cross)
	return -EOPNOTSUPP;

	ret = viortc_hw_xtstamp_params(&hw_counter, &cs_id);
	if (ret)
	return ret;

	ktime_get_snapshot(&history_begin);
	if (history_begin.cs_id != cs_id)
	return -EOPNOTSUPP;

	/*
	* Getting the timestamp can take many milliseconds with a slow Virtio
	* device. This is too long for viortc_ptp_get_time_fn() passed to
	* get_device_system_crosststamp(), which has to usually return before
	* the timekeeper seqcount increases (every tick or so).
	*
	* So, get the actual cross-timestamp first.
	*/
	ret = viortc_ptp_do_xtstamp(vio_ptp, hw_counter, cs_id, &ctx);
	if (ret)
	return ret;

	ret = get_device_system_crosststamp(viortc_ptp_get_time_fn, &ctx,
	&history_begin, xtstamp);
	if (ret)
	pr_debug("%s: get_device_system_crosststamp() returned %d\n",
	__func__, ret);

	return ret;
	}

	/* viortc_ptp_adjfine() - unsupported PTP clock adjfine op */
	static int viortc_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
	{
	return -EOPNOTSUPP;
	}

	/* viortc_ptp_adjtime() - unsupported PTP clock adjtime op */
	static int viortc_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
	{
	return -EOPNOTSUPP;
	}

	/* viortc_ptp_settime64() - unsupported PTP clock settime64 op */
	static int viortc_ptp_settime64(struct ptp_clock_info *ptp,
	const struct timespec64 *ts)
	{
	return -EOPNOTSUPP;
	}

	/*
	* viortc_ptp_gettimex64() - PTP clock gettimex64 op
	*
	* Context: Process context.
	*/
	static int viortc_ptp_gettimex64(struct ptp_clock_info *ptp,
	struct timespec64 *ts,
	struct ptp_system_timestamp *sts)
	{
	struct viortc_ptp_clock *vio_ptp =
	container_of(ptp, struct viortc_ptp_clock, ptp_info);
	int ret;
	u64 ns;

	ptp_read_system_prets(sts);
	ret = viortc_read(vio_ptp->viortc, vio_ptp->vio_clk_id, &ns);
	ptp_read_system_postts(sts);

	if (ret)
	return ret;

	if (ns > (u64)S64_MAX)
	return -EINVAL;

	*ts = ns_to_timespec64((s64)ns);

	return 0;
	}

	/* viortc_ptp_enable() - unsupported PTP clock enable op */
	static int viortc_ptp_enable(struct ptp_clock_info *ptp,
	struct ptp_clock_request *rq, int on)
	{
	return -EOPNOTSUPP;
	}

	/*
	* viortc_ptp_info_template - ptp_clock_info template
	*
	* The .name member will be set for individual virtio_rtc PTP clocks.
	*
	* The .getcrosststamp member will be cleared for PTP clocks not supporting
	* crosststamp.
	*/
	static const struct ptp_clock_info viortc_ptp_info_template = {
	.owner = THIS_MODULE,
	/* .name is set according to clock type */
	.adjfine = viortc_ptp_adjfine,
	.adjtime = viortc_ptp_adjtime,
	.gettimex64 = viortc_ptp_gettimex64,
	.settime64 = viortc_ptp_settime64,
	.enable = viortc_ptp_enable,
	.getcrosststamp = viortc_ptp_getcrosststamp,
	};

	/**
	* viortc_ptp_unregister() - PTP clock unregistering wrapper
	* @vio_ptp: virtio_rtc PTP clock
	* @parent_dev: parent device of PTP clock
	*
	* Return: Zero on success, negative error code otherwise.
	*/
	int viortc_ptp_unregister(struct viortc_ptp_clock *vio_ptp,
	struct device *parent_dev)
	{
	int ret = ptp_clock_unregister(vio_ptp->ptp_clock);

	if (!ret)
	devm_kfree(parent_dev, vio_ptp);

	return ret;
	}

	/**
	* viortc_ptp_get_cross_cap() - get xtstamp support info from device
	* @viortc: virtio_rtc device data
	* @vio_ptp: virtio_rtc PTP clock abstraction
	*
	* Context: Process context.
	* Return: Zero on success, negative error code otherwise.
	*/
	static int viortc_ptp_get_cross_cap(struct viortc_dev *viortc,
	struct viortc_ptp_clock *vio_ptp)
	{
	enum clocksource_ids cs_id;
	bool xtstamp_supported;
	u8 hw_counter;
	int ret;

	ret = viortc_hw_xtstamp_params(&hw_counter, &cs_id);
	if (ret) {
	vio_ptp->have_cross = false;
	return 0;
	}

	ret = viortc_cross_cap(viortc, vio_ptp->vio_clk_id, hw_counter,
	&xtstamp_supported);
	if (ret)
	return ret;

	vio_ptp->have_cross = xtstamp_supported;

	return 0;
	}

	/**
	* viortc_ptp_register() - prepare and register PTP clock
	* @viortc: virtio_rtc device data
	* @parent_dev: parent device for PTP clock
	* @vio_clk_id: id of virtio_rtc clock which backs PTP clock
	* @ptp_clock_name: PTP clock name
	*
	* Context: Process context.
	* Return: Pointer on success, ERR_PTR() otherwise; NULL if PTP clock support
	* not available.
	*/
	struct viortc_ptp_clock viortc_ptp_register(struct viortc_dev viortc,
	struct device *parent_dev,
	u16 vio_clk_id,
	const char *ptp_clock_name)
	{
	struct viortc_ptp_clock *vio_ptp;
	struct ptp_clock *ptp_clock;
	ssize_t len;
	int ret;

	vio_ptp = devm_kzalloc(parent_dev, sizeof(*vio_ptp), GFP_KERNEL);
	if (!vio_ptp)
	return ERR_PTR(-ENOMEM);

	vio_ptp->viortc = viortc;
	vio_ptp->vio_clk_id = vio_clk_id;
	vio_ptp->ptp_info = viortc_ptp_info_template;
	len = strscpy(vio_ptp->ptp_info.name, ptp_clock_name,
	sizeof(vio_ptp->ptp_info.name));
	if (len < 0) {
	ret = len;
	goto err_free_dev;
	}

	ret = viortc_ptp_get_cross_cap(viortc, vio_ptp);
	if (ret)
	goto err_free_dev;

	if (!vio_ptp->have_cross)
	vio_ptp->ptp_info.getcrosststamp = NULL;

	ptp_clock = ptp_clock_register(&vio_ptp->ptp_info, parent_dev);
	if (IS_ERR(ptp_clock))
	goto err_on_register;

	vio_ptp->ptp_clock = ptp_clock;

	return vio_ptp;

	err_on_register:
	ret = PTR_ERR(ptp_clock);

	err_free_dev:
	devm_kfree(parent_dev, vio_ptp);
	return ERR_PTR(ret);
	}