1 files changed, 347 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_rtc_ptp.c b/drivers/virtio/virtio_rtc_ptp.c
new file mode 100644
index 000000000000..f84599950cd4
--- /dev/null
+++ b/drivers/virtio/virtio_rtc_ptp.c
@@ -0,0 +1,347 @@
+// 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);
+}