Merge tag 'hte/for-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux

Pull hardware timestamping subsystem from Thierry Reding:
 "This contains the new HTE (hardware timestamping engine) subsystem
  that has been in the works for a couple of months now.

  The infrastructure provided allows for drivers to register as hardware
  timestamp providers, while consumers will be able to request events
  that they are interested in (such as GPIOs and IRQs) to be timestamped
  by the hardware providers.

  Note that this currently supports only one provider, but there seems
  to be enough interest in this functionality and we expect to see more
  drivers added once this is merged"

[ Linus Walleij mentions the Intel PMC in the Elkhart and Tiger Lake
  platforms as another future timestamp provider ]

* tag 'hte/for-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux:
  dt-bindings: timestamp: Correct id path
  dt-bindings: Renamed hte directory to timestamp
  hte: Uninitialized variable in hte_ts_get()
  hte: Fix off by one in hte_push_ts_ns()
  hte: Fix possible use-after-free in tegra_hte_test_remove()
  hte: Remove unused including <linux/version.h>
  MAINTAINERS: Add HTE Subsystem
  hte: Add Tegra HTE test driver
  tools: gpio: Add new hardware clock type
  gpiolib: cdev: Add hardware timestamp clock type
  gpio: tegra186: Add HTE support
  gpiolib: Add HTE support
  dt-bindings: Add HTE bindings
  hte: Add Tegra194 HTE kernel provider
  drivers: Add hardware timestamp engine (HTE) subsystem
  Documentation: Add HTE subsystem guide

Documentation/devicetree/bindings/timestamp/hardware-timestamps-common.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/timestamp/hardware-timestamps-common.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Hardware timestamp providers
+
+maintainers:
+  - Dipen Patel <dipenp@nvidia.com>
+
+description:
+  Some devices/SoCs have hardware timestamp engines (HTE) which can use
+  hardware means to timestamp entity in realtime. The entity could be anything
+  from GPIOs, IRQs, Bus and so on. The hardware timestamp engine present
+  itself as a provider with the bindings described in this document.
+
+properties:
+  $nodename:
+    pattern: "^timestamp(@.*|-[0-9a-f])?$"
+
+  "#timestamp-cells":
+    description:
+      Number of cells in a HTE specifier.
+
+required:
+  - "#timestamp-cells"
+
+additionalProperties: true

Documentation/devicetree/bindings/timestamp/hte-consumer.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/timestamp/hte-consumer.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: HTE Consumer Device Tree Bindings
+
+maintainers:
+  - Dipen Patel <dipenp@nvidia.com>
+
+select: true
+
+properties:
+  timestamps:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    description:
+      The list of HTE provider phandle. The first cell must represent the
+      provider phandle followed by the line identifiers. The meaning of the
+      line identifier and exact number of arguments must be specified in the
+      HTE provider device tree binding document.
+
+  timestamp-names:
+    $ref: /schemas/types.yaml#/definitions/string-array
+    description:
+      An optional string property to label each line specifier present in the
+      timestamp property.
+
+dependencies:
+  timestamp-names: [ timestamps ]
+
+additionalProperties: true
+
+examples:
+  - |
+    hte_tegra_consumer {
+              timestamps = <&tegra_hte_aon 0x9>, <&tegra_hte_lic 0x19>;
+              timestamp-names = "hte-gpio", "hte-i2c";
+    };

Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/timestamp/nvidia,tegra194-hte.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Tegra194 on chip generic hardware timestamping engine (HTE)
+
+maintainers:
+  - Dipen Patel <dipenp@nvidia.com>
+
+description:
+  Tegra SoC has two instances of generic hardware timestamping engines (GTE)
+  known as GTE GPIO and GTE IRQ, which can monitor subset of GPIO and on chip
+  IRQ lines for the state change respectively, upon detection it will record
+  timestamp (taken from system counter) in its internal hardware FIFO. It has
+  a bitmap array arranged in 32bit slices where each bit represent signal/line
+  to enable or disable for the hardware timestamping. The GTE GPIO monitors
+  GPIO lines from the AON (always on) GPIO controller.
+
+properties:
+  compatible:
+    enum:
+      - nvidia,tegra194-gte-aon
+      - nvidia,tegra194-gte-lic
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  nvidia,int-threshold:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      HTE device generates its interrupt based on this u32 FIFO threshold
+      value. The recommended value is 1.
+    minimum: 1
+    maximum: 256
+
+  nvidia,slices:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      HTE lines are arranged in 32 bit slice where each bit represents different
+      line/signal that it can enable/configure for the timestamp. It is u32
+      property and depends on the HTE instance in the chip. The value 3 is for
+      GPIO GTE and 11 for IRQ GTE.
+    enum: [3, 11]
+
+  '#timestamp-cells':
+    description:
+      This represents number of line id arguments as specified by the
+      consumers. For the GTE IRQ, this is IRQ number as mentioned in the
+      SoC technical reference manual. For the GTE GPIO, its value is same as
+      mentioned in the nvidia GPIO device tree binding document.
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - nvidia,slices
+  - "#timestamp-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    tegra_hte_aon: timestamp@c1e0000 {
+              compatible = "nvidia,tegra194-gte-aon";
+              reg = <0xc1e0000 0x10000>;
+              interrupts = <0 13 0x4>;
+              nvidia,int-threshold = <1>;
+              nvidia,slices = <3>;
+              #timestamp-cells = <1>;
+    };
+
+  - |
+    tegra_hte_lic: timestamp@3aa0000 {
+              compatible = "nvidia,tegra194-gte-lic";
+              reg = <0x3aa0000 0x10000>;
+              interrupts = <0 11 0x4>;
+              nvidia,int-threshold = <1>;
+              nvidia,slices = <11>;
+              #timestamp-cells = <1>;
+    };
+
+...

Documentation/hte/hte.rst

+.. SPDX-License-Identifier: GPL-2.0+
+
+============================================
+The Linux Hardware Timestamping Engine (HTE)
+============================================
+
+:Author: Dipen Patel
+
+Introduction
+------------
+
+Certain devices have built in hardware timestamping engines which can
+monitor sets of system signals, lines, buses etc... in realtime for state
+change; upon detecting the change they can automatically store the timestamp at
+the moment of occurrence. Such functionality may help achieve better accuracy
+in obtaining timestamps than using software counterparts i.e. ktime and
+friends.
+
+This document describes the API that can be used by hardware timestamping
+engine provider and consumer drivers that want to use the hardware timestamping
+engine (HTE) framework. Both consumers and providers must include
+``#include <linux/hte.h>``.
+
+The HTE framework APIs for the providers
+----------------------------------------
+
+.. kernel-doc:: drivers/hte/hte.c
+   :functions: devm_hte_register_chip hte_push_ts_ns
+
+The HTE framework APIs for the consumers
+----------------------------------------
+
+.. kernel-doc:: drivers/hte/hte.c
+   :functions: hte_init_line_attr hte_ts_get hte_ts_put devm_hte_request_ts_ns hte_request_ts_ns hte_enable_ts hte_disable_ts of_hte_req_count hte_get_clk_src_info
+
+The HTE framework public structures
+-----------------------------------
+.. kernel-doc:: include/linux/hte.h
+
+More on the HTE timestamp data
+------------------------------
+The ``struct hte_ts_data`` is used to pass timestamp details between the
+consumers and the providers. It expresses timestamp data in nanoseconds in
+u64. An example of the typical timestamp data life cycle, for the GPIO line is
+as follows::
+
+ - Monitors GPIO line change.
+ - Detects the state change on GPIO line.
+ - Converts timestamps in nanoseconds.
+ - Stores GPIO raw level in raw_level variable if the provider has that
+ hardware capability.
+ - Pushes this hte_ts_data object to HTE subsystem.
+ - HTE subsystem increments seq counter and invokes consumer provided callback.
+ Based on callback return value, the HTE core invokes secondary callback in
+ the thread context.
+
+HTE subsystem debugfs attributes
+--------------------------------
+HTE subsystem creates debugfs attributes at ``/sys/kernel/debug/hte/``.
+It also creates line/signal-related debugfs attributes at
+``/sys/kernel/debug/hte/<provider>/<label or line id>/``. Note that these
+attributes are read-only.
+
+`ts_requested`
+		The total number of entities requested from the given provider,
+		where entity is specified by the provider and could represent
+		lines, GPIO, chip signals, buses etc...
+                The attribute will be available at
+		``/sys/kernel/debug/hte/<provider>/``.
+
+`total_ts`
+		The total number of entities supported by the provider.
+                The attribute will be available at
+		``/sys/kernel/debug/hte/<provider>/``.
+
+`dropped_timestamps`
+		The dropped timestamps for a given line.
+                The attribute will be available at
+		``/sys/kernel/debug/hte/<provider>/<label or line id>/``.

Documentation/hte/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+============================================
+The Linux Hardware Timestamping Engine (HTE)
+============================================
+
+The HTE Subsystem
+=================
+
+.. toctree::
+   :maxdepth: 1
+
+   hte
+
+HTE Tegra Provider
+==================
+
+.. toctree::
+   :maxdepth: 1
+
+   tegra194-hte
+

Documentation/hte/tegra194-hte.rst

+.. SPDX-License-Identifier: GPL-2.0+
+
+HTE Kernel provider driver
+==========================
+
+Description
+-----------
+The Nvidia tegra194 HTE provider driver implements two GTE
+(Generic Timestamping Engine) instances: 1) GPIO GTE and 2) LIC
+(Legacy Interrupt Controller) IRQ GTE. Both GTE instances get the
+timestamp from the system counter TSC which has 31.25MHz clock rate, and the
+driver converts clock tick rate to nanoseconds before storing it as timestamp
+value.
+
+GPIO GTE
+--------
+
+This GTE instance timestamps GPIO in real time. For that to happen GPIO
+needs to be configured as input. The always on (AON) GPIO controller instance
+supports timestamping GPIOs in real time and it has 39 GPIO lines. The GPIO GTE
+and AON GPIO controller are tightly coupled as it requires very specific bits
+to be set in GPIO config register before GPIO GTE can be used, for that GPIOLIB
+adds two optional APIs as below. The GPIO GTE code supports both kernel
+and userspace consumers. The kernel space consumers can directly talk to HTE
+subsystem while userspace consumers timestamp requests go through GPIOLIB CDEV
+framework to HTE subsystem.
+
+.. kernel-doc:: drivers/gpio/gpiolib.c
+   :functions: gpiod_enable_hw_timestamp_ns gpiod_disable_hw_timestamp_ns
+
+For userspace consumers, GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE flag must be
+specified during IOCTL calls. Refer to ``tools/gpio/gpio-event-mon.c``, which
+returns the timestamp in nanoseconds.
+
+LIC (Legacy Interrupt Controller) IRQ GTE
+-----------------------------------------
+
+This GTE instance timestamps LIC IRQ lines in real time. There are 352 IRQ
+lines which this instance can add timestamps to in real time. The hte
+devicetree binding described at ``Documentation/devicetree/bindings/hte/``
+provides an example of how a consumer can request an IRQ line. Since it is a
+one-to-one mapping with IRQ GTE provider, consumers can simply specify the IRQ
+number that they are interested in. There is no userspace consumer support for
+this GTE instance in the HTE framework.
+
+The provider source code of both IRQ and GPIO GTE instances is located at
+``drivers/hte/hte-tegra194.c``. The test driver
+``drivers/hte/hte-tegra194-test.c`` demonstrates HTE API usage for both IRQ
+and GPIO GTE.

Documentation/index.rst

@@ -137,6 +137,7 @@ needed).
    scheduler/index
    mhi/index
    peci/index
+   hte/index
 
 Architecture-agnostic documentation
 -----------------------------------

MAINTAINERS

@@ -9077,6 +9077,14 @@ L:	linux-input@vger.kernel.org
 S:	Maintained
 F:	drivers/input/touchscreen/htcpen.c
 
+HTE SUBSYSTEM
+M:	Dipen Patel <dipenp@nvidia.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/timestamp/
+F:	Documentation/hte/
+F:	drivers/hte/
+F:	include/linux/hte.h
+
 HTS221 TEMPERATURE-HUMIDITY IIO DRIVER
 M:	Lorenzo Bianconi <lorenzo@kernel.org>
 L:	linux-iio@vger.kernel.org

drivers/Kconfig

@@ -237,4 +237,6 @@ source "drivers/most/Kconfig"
 
 source "drivers/peci/Kconfig"
 
+source "drivers/hte/Kconfig"
+
 endmenu

drivers/Makefile

@@ -187,3 +187,4 @@ obj-$(CONFIG_INTERCONNECT)	+= interconnect/
 obj-$(CONFIG_COUNTER)		+= counter/
 obj-$(CONFIG_MOST)		+= most/
 obj-$(CONFIG_PECI)		+= peci/
+obj-$(CONFIG_HTE)		+= hte/

drivers/gpio/gpio-tegra186.c

 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright (c) 2016-2017 NVIDIA Corporation
+ * Copyright (c) 2016-2022 NVIDIA Corporation
  *
  * Author: Thierry Reding <treding@nvidia.com>
+ *	   Dipen Patel <dpatel@nvidia.com>
  */
 
 #include <linux/gpio/driver.h>
@@ -11,6 +12,7 @@
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
+#include <linux/hte.h>
 
 #include <dt-bindings/gpio/tegra186-gpio.h>
 #include <dt-bindings/gpio/tegra194-gpio.h>
@@ -36,6 +38,7 @@
 #define  TEGRA186_GPIO_ENABLE_CONFIG_TRIGGER_LEVEL BIT(4)
 #define  TEGRA186_GPIO_ENABLE_CONFIG_DEBOUNCE BIT(5)
 #define  TEGRA186_GPIO_ENABLE_CONFIG_INTERRUPT BIT(6)
+#define  TEGRA186_GPIO_ENABLE_CONFIG_TIMESTAMP_FUNC BIT(7)
 
 #define TEGRA186_GPIO_DEBOUNCE_CONTROL 0x04
 #define  TEGRA186_GPIO_DEBOUNCE_CONTROL_THRESHOLD(x) ((x) & 0xff)
@@ -76,6 +79,7 @@ struct tegra_gpio_soc {
 	const struct tegra186_pin_range *pin_ranges;
 	unsigned int num_pin_ranges;
 	const char *pinmux;
+	bool has_gte;
 };
 
 struct tegra_gpio {
@@ -193,6 +197,76 @@ static int tegra186_gpio_direction_output(struct gpio_chip *chip,
 	return 0;
 }
 
+#define HTE_BOTH_EDGES	(HTE_RISING_EDGE_TS | HTE_FALLING_EDGE_TS)
+
+static int tegra186_gpio_en_hw_ts(struct gpio_chip *gc, u32 offset,
+				  unsigned long flags)
+{
+	struct tegra_gpio *gpio;
+	void __iomem *base;
+	int value;
+
+	if (!gc)
+		return -EINVAL;
+
+	gpio = gpiochip_get_data(gc);
+	if (!gpio)
+		return -ENODEV;
+
+	base = tegra186_gpio_get_base(gpio, offset);
+	if (WARN_ON(base == NULL))
+		return -EINVAL;
+
+	value = readl(base + TEGRA186_GPIO_ENABLE_CONFIG);
+	value |= TEGRA186_GPIO_ENABLE_CONFIG_TIMESTAMP_FUNC;
+
+	if (flags == HTE_BOTH_EDGES) {
+		value |= TEGRA186_GPIO_ENABLE_CONFIG_TRIGGER_TYPE_DOUBLE_EDGE;
+	} else if (flags == HTE_RISING_EDGE_TS) {
+		value |= TEGRA186_GPIO_ENABLE_CONFIG_TRIGGER_TYPE_SINGLE_EDGE;
+		value |= TEGRA186_GPIO_ENABLE_CONFIG_TRIGGER_LEVEL;
+	} else if (flags == HTE_FALLING_EDGE_TS) {
+		value |= TEGRA186_GPIO_ENABLE_CONFIG_TRIGGER_TYPE_SINGLE_EDGE;
+	}
+
+	writel(value, base + TEGRA186_GPIO_ENABLE_CONFIG);
+
+	return 0;
+}
+
+static int tegra186_gpio_dis_hw_ts(struct gpio_chip *gc, u32 offset,
+				   unsigned long flags)
+{
+	struct tegra_gpio *gpio;
+	void __iomem *base;
+	int value;
+
+	if (!gc)
+		return -EINVAL;
+
+	gpio = gpiochip_get_data(gc);
+	if (!gpio)
+		return -ENODEV;
+
+	base = tegra186_gpio_get_base(gpio, offset);
+	if (WARN_ON(base == NULL))
+		return -EINVAL;
+
+	value = readl(base + TEGRA186_GPIO_ENABLE_CONFIG);
+	value &= ~TEGRA186_GPIO_ENABLE_CONFIG_TIMESTAMP_FUNC;
+	if (flags == HTE_BOTH_EDGES) {
+		value &= ~TEGRA186_GPIO_ENABLE_CONFIG_TRIGGER_TYPE_DOUBLE_EDGE;
+	} else if (flags == HTE_RISING_EDGE_TS) {
+		value &= ~TEGRA186_GPIO_ENABLE_CONFIG_TRIGGER_TYPE_SINGLE_EDGE;
+		value &= ~TEGRA186_GPIO_ENABLE_CONFIG_TRIGGER_LEVEL;
+	} else if (flags == HTE_FALLING_EDGE_TS) {
+		value &= ~TEGRA186_GPIO_ENABLE_CONFIG_TRIGGER_TYPE_SINGLE_EDGE;
+	}
+	writel(value, base + TEGRA186_GPIO_ENABLE_CONFIG);
+
+	return 0;
+}
+
 static int tegra186_gpio_get(struct gpio_chip *chip, unsigned int offset)
 {
 	struct tegra_gpio *gpio = gpiochip_get_data(chip);
@@ -747,6 +821,10 @@ static int tegra186_gpio_probe(struct platform_device *pdev)
 	gpio->gpio.set = tegra186_gpio_set;
 	gpio->gpio.set_config = tegra186_gpio_set_config;
 	gpio->gpio.add_pin_ranges = tegra186_gpio_add_pin_ranges;
+	if (gpio->soc->has_gte) {
+		gpio->gpio.en_hw_timestamp = tegra186_gpio_en_hw_ts;
+		gpio->gpio.dis_hw_timestamp = tegra186_gpio_dis_hw_ts;
+	}
 
 	gpio->gpio.base = -1;
 
@@ -991,6 +1069,7 @@ static const struct tegra_gpio_soc tegra194_aon_soc = {
 	.name = "tegra194-gpio-aon",
 	.instance = 1,
 	.num_irqs_per_bank = 8,
+	.has_gte = true,
 };
 
 #define TEGRA234_MAIN_GPIO_PORT(_name, _bank, _port, _pins)	\

drivers/gpio/gpiolib-cdev.c

@@ -24,6 +24,7 @@
 #include <linux/timekeeping.h>
 #include <linux/uaccess.h>
 #include <linux/workqueue.h>
+#include <linux/hte.h>
 #include <uapi/linux/gpio.h>
 
 #include "gpiolib.h"
@@ -464,6 +465,25 @@ struct line {
 	 * stale value.
 	 */
 	unsigned int level;
+	/*
+	 * -- hte specific fields --
+	 */
+	struct hte_ts_desc hdesc;
+	/*
+	 * HTE provider sets line level at the time of event. The valid
+	 * value is 0 or 1 and negative value for an error.
+	 */
+	int raw_level;
+	/*
+	 * when sw_debounce is set on HTE enabled line, this is running
+	 * counter of the discarded events.
+	 */
+	u32 total_discard_seq;
+	/*
+	 * when sw_debounce is set on HTE enabled line, this variable records
+	 * last sequence number before debounce period expires.
+	 */
+	u32 last_seqno;
 };
 
 /**
@@ -518,6 +538,7 @@ struct linereq {
 	 GPIO_V2_LINE_DRIVE_FLAGS | \
 	 GPIO_V2_LINE_EDGE_FLAGS | \
 	 GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME | \
+	 GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE | \
 	 GPIO_V2_LINE_BIAS_FLAGS)
 
 static void linereq_put_event(struct linereq *lr,
@@ -542,10 +563,98 @@ static u64 line_event_timestamp(struct line *line)
 {
 	if (test_bit(FLAG_EVENT_CLOCK_REALTIME, &line->desc->flags))
 		return ktime_get_real_ns();
+	else if (test_bit(FLAG_EVENT_CLOCK_HTE, &line->desc->flags))
+		return line->timestamp_ns;
 
 	return ktime_get_ns();
 }
 
+static enum hte_return process_hw_ts_thread(void *p)
+{
+	struct line *line;
+	struct linereq *lr;
+	struct gpio_v2_line_event le;
+	int level;
+	u64 eflags;
+
+	if (!p)
+		return HTE_CB_HANDLED;
+
+	line = p;
+	lr = line->req;
+
+	memset(&le, 0, sizeof(le));
+
+	le.timestamp_ns = line->timestamp_ns;
+	eflags = READ_ONCE(line->eflags);
+
+	if (eflags == GPIO_V2_LINE_FLAG_EDGE_BOTH) {
+		if (line->raw_level >= 0) {
+			if (test_bit(FLAG_ACTIVE_LOW, &line->desc->flags))
+				level = !line->raw_level;
+			else
+				level = line->raw_level;
+		} else {
+			level = gpiod_get_value_cansleep(line->desc);
+		}
+
+		if (level)
+			le.id = GPIO_V2_LINE_EVENT_RISING_EDGE;
+		else
+			le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE;
+	} else if (eflags == GPIO_V2_LINE_FLAG_EDGE_RISING) {
+		/* Emit low-to-high event */
+		le.id = GPIO_V2_LINE_EVENT_RISING_EDGE;
+	} else if (eflags == GPIO_V2_LINE_FLAG_EDGE_FALLING) {
+		/* Emit high-to-low event */
+		le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE;
+	} else {
+		return HTE_CB_HANDLED;
+	}
+	le.line_seqno = line->line_seqno;
+	le.seqno = (lr->num_lines == 1) ? le.line_seqno : line->req_seqno;
+	le.offset = gpio_chip_hwgpio(line->desc);
+
+	linereq_put_event(lr, &le);
+
+	return HTE_CB_HANDLED;
+}
+
+static enum hte_return process_hw_ts(struct hte_ts_data *ts, void *p)
+{
+	struct line *line;
+	struct linereq *lr;
+	int diff_seqno = 0;
+
+	if (!ts || !p)
+		return HTE_CB_HANDLED;
+
+	line = p;
+	line->timestamp_ns = ts->tsc;
+	line->raw_level = ts->raw_level;
+	lr = line->req;
+
+	if (READ_ONCE(line->sw_debounced)) {
+		line->total_discard_seq++;
+		line->last_seqno = ts->seq;
+		mod_delayed_work(system_wq, &line->work,
+		  usecs_to_jiffies(READ_ONCE(line->desc->debounce_period_us)));
+	} else {
+		if (unlikely(ts->seq < line->line_seqno))
+			return HTE_CB_HANDLED;
+
+		diff_seqno = ts->seq - line->line_seqno;
+		line->line_seqno = ts->seq;
+		if (lr->num_lines != 1)
+			line->req_seqno = atomic_add_return(diff_seqno,
+							    &lr->seqno);
+
+		return HTE_RUN_SECOND_CB;
+	}
+
+	return HTE_CB_HANDLED;
+}
+
 static irqreturn_t edge_irq_thread(int irq, void *p)
 {
 	struct line *line = p;
@@ -651,10 +760,16 @@ static void debounce_work_func(struct work_struct *work)
 	struct gpio_v2_line_event le;
 	struct line *line = container_of(work, struct line, work.work);
 	struct linereq *lr;
-	int level;
+	int level, diff_seqno;
 	u64 eflags;
 
+	if (test_bit(FLAG_EVENT_CLOCK_HTE, &line->desc->flags)) {
+		level = line->raw_level;
+		if (level < 0)
+			level = gpiod_get_raw_value_cansleep(line->desc);
+	} else {
 		level = gpiod_get_raw_value_cansleep(line->desc);
+	}
 	if (level < 0) {
 		pr_debug_ratelimited("debouncer failed to read line value\n");
 		return;
@@ -685,10 +800,21 @@ static void debounce_work_func(struct work_struct *work)
 	lr = line->req;
 	le.timestamp_ns = line_event_timestamp(line);
 	le.offset = gpio_chip_hwgpio(line->desc);
+	if (test_bit(FLAG_EVENT_CLOCK_HTE, &line->desc->flags)) {
+		/* discard events except the last one */
+		line->total_discard_seq -= 1;
+		diff_seqno = line->last_seqno - line->total_discard_seq -
+				line->line_seqno;
+		line->line_seqno = line->last_seqno - line->total_discard_seq;
+		le.line_seqno = line->line_seqno;
+		le.seqno = (lr->num_lines == 1) ?
+			le.line_seqno : atomic_add_return(diff_seqno, &lr->seqno);
+	} else {
 		line->line_seqno++;
 		le.line_seqno = line->line_seqno;
 		le.seqno = (lr->num_lines == 1) ?
 			le.line_seqno : atomic_inc_return(&lr->seqno);
+	}
 
 	if (level)
 		/* Emit low-to-high event */
@@ -700,8 +826,34 @@ static void debounce_work_func(struct work_struct *work)
 	linereq_put_event(lr, &le);
 }
 
+static int hte_edge_setup(struct line *line, u64 eflags)
+{
+	int ret;
+	unsigned long flags = 0;
+	struct hte_ts_desc *hdesc = &line->hdesc;
+
+	if (eflags & GPIO_V2_LINE_FLAG_EDGE_RISING)
+		flags |= test_bit(FLAG_ACTIVE_LOW, &line->desc->flags) ?
+				  HTE_FALLING_EDGE_TS : HTE_RISING_EDGE_TS;
+	if (eflags & GPIO_V2_LINE_FLAG_EDGE_FALLING)
+		flags |= test_bit(FLAG_ACTIVE_LOW, &line->desc->flags) ?
+				  HTE_RISING_EDGE_TS : HTE_FALLING_EDGE_TS;
+
+	line->total_discard_seq = 0;
+
+	hte_init_line_attr(hdesc, desc_to_gpio(line->desc), flags,
+			   NULL, line->desc);
+
+	ret = hte_ts_get(NULL, hdesc, 0);
+	if (ret)
+		return ret;
+
+	return hte_request_ts_ns(hdesc, process_hw_ts,
+				 process_hw_ts_thread, line);
+}
+
 static int debounce_setup(struct line *line,
-			  unsigned int debounce_period_us)
+			  unsigned int debounce_period_us, bool hte_req)
 {
 	unsigned long irqflags;
 	int ret, level, irq;
@@ -721,19 +873,27 @@ static int debounce_setup(struct line *line,
 		if (level < 0)
 			return level;
 
+		if (!hte_req) {
 			irq = gpiod_to_irq(line->desc);
 			if (irq < 0)
 				return -ENXIO;
 
-		WRITE_ONCE(line->level, level);
 			irqflags = IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING;
 			ret = request_irq(irq, debounce_irq_handler, irqflags,
 					  line->req->label, line);
 			if (ret)
 				return ret;
+			line->irq = irq;
+		} else {
+			ret = hte_edge_setup(line,
+					     GPIO_V2_LINE_FLAG_EDGE_RISING |
+					     GPIO_V2_LINE_FLAG_EDGE_FALLING);
+			if (ret)
+				return ret;
+		}
 
+		WRITE_ONCE(line->level, level);
 		WRITE_ONCE(line->sw_debounced, 1);
-		line->irq = irq;
 	}
 	return 0;
 }
@@ -766,13 +926,16 @@ static u32 gpio_v2_line_config_debounce_period(struct gpio_v2_line_config *lc,
 	return 0;
 }
 
-static void edge_detector_stop(struct line *line)
+static void edge_detector_stop(struct line *line, bool hte_en)
 {
-	if (line->irq) {
+	if (line->irq && !hte_en) {
 		free_irq(line->irq, line);
 		line->irq = 0;
 	}
 
+	if (hte_en)
+		hte_ts_put(&line->hdesc);
+
 	cancel_delayed_work_sync(&line->work);
 	WRITE_ONCE(line->sw_debounced, 0);
 	WRITE_ONCE(line->eflags, 0);
@@ -784,7 +947,7 @@ static void edge_detector_stop(struct line *line)
 static int edge_detector_setup(struct line *line,
 			       struct gpio_v2_line_config *lc,
 			       unsigned int line_idx,
-			       u64 eflags)
+			       u64 eflags, bool hte_req)
 {
 	u32 debounce_period_us;
 	unsigned long irqflags = 0;
@@ -799,7 +962,7 @@ static int edge_detector_setup(struct line *line,
 	WRITE_ONCE(line->eflags, eflags);
 	if (gpio_v2_line_config_debounced(lc, line_idx)) {
 		debounce_period_us = gpio_v2_line_config_debounce_period(lc, line_idx);
-		ret = debounce_setup(line, debounce_period_us);
+		ret = debounce_setup(line, debounce_period_us, hte_req);
 		if (ret)
 			return ret;
 		WRITE_ONCE(line->desc->debounce_period_us, debounce_period_us);
@@ -809,6 +972,9 @@ static int edge_detector_setup(struct line *line,
 	if (!eflags || READ_ONCE(line->sw_debounced))
 		return 0;
 
+	if (hte_req)
+		return hte_edge_setup(line, eflags);
+
 	irq = gpiod_to_irq(line->desc);
 	if (irq < 0)
 		return -ENXIO;
@@ -834,13 +1000,18 @@ static int edge_detector_setup(struct line *line,
 static int edge_detector_update(struct line *line,
 				struct gpio_v2_line_config *lc,
 				unsigned int line_idx,
-				u64 eflags, bool polarity_change)
+				u64 flags, bool polarity_change,
+				bool prev_hte_flag)
 {
+	u64 eflags = flags & GPIO_V2_LINE_EDGE_FLAGS;
 	unsigned int debounce_period_us =
 			gpio_v2_line_config_debounce_period(lc, line_idx);
+	bool hte_change = (prev_hte_flag !=
+		      ((flags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE) != 0));
 
 	if ((READ_ONCE(line->eflags) == eflags) && !polarity_change &&
-	    (READ_ONCE(line->desc->debounce_period_us) == debounce_period_us))
+	    (READ_ONCE(line->desc->debounce_period_us) == debounce_period_us)
+	    && !hte_change)
 		return 0;
 
 	/* sw debounced and still will be...*/
@@ -851,11 +1022,12 @@ static int edge_detector_update(struct line *line,
 	}
 
 	/* reconfiguring edge detection or sw debounce being disabled */
-	if ((line->irq && !READ_ONCE(line->sw_debounced)) ||
+	if ((line->irq && !READ_ONCE(line->sw_debounced)) || prev_hte_flag ||
 	    (!debounce_period_us && READ_ONCE(line->sw_debounced)))
-		edge_detector_stop(line);
+		edge_detector_stop(line, prev_hte_flag);
 
-	return edge_detector_setup(line, lc, line_idx, eflags);
+	return edge_detector_setup(line, lc, line_idx, eflags,
+				   flags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE);
 }
 
 static u64 gpio_v2_line_config_flags(struct gpio_v2_line_config *lc,
@@ -891,7 +1063,6 @@ static int gpio_v2_line_flags_validate(u64 flags)
 	/* Return an error if an unknown flag is set */
 	if (flags & ~GPIO_V2_LINE_VALID_FLAGS)
 		return -EINVAL;
-
 	/*
 	 * Do not allow both INPUT and OUTPUT flags to be set as they are
 	 * contradictory.
@@ -900,6 +1071,11 @@ static int gpio_v2_line_flags_validate(u64 flags)
 	    (flags & GPIO_V2_LINE_FLAG_OUTPUT))
 		return -EINVAL;
 
+	/* Only allow one event clock source */
+	if ((flags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME) &&
+	    (flags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE))
+		return -EINVAL;
+
 	/* Edge detection requires explicit input. */
 	if ((flags & GPIO_V2_LINE_EDGE_FLAGS) &&
 	    !(flags & GPIO_V2_LINE_FLAG_INPUT))
@@ -992,6 +1168,8 @@ static void gpio_v2_line_config_flags_to_desc_flags(u64 flags,
 
 	assign_bit(FLAG_EVENT_CLOCK_REALTIME, flagsp,
 		   flags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME);
+	assign_bit(FLAG_EVENT_CLOCK_HTE, flagsp,
+		   flags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE);
 }
 
 static long linereq_get_values(struct linereq *lr, void __user *ip)
@@ -1121,6 +1299,7 @@ static long linereq_set_config_unlocked(struct linereq *lr,
 	unsigned int i;
 	u64 flags;
 	bool polarity_change;
+	bool prev_hte_flag;
 	int ret;
 
 	for (i = 0; i < lr->num_lines; i++) {
@@ -1130,6 +1309,8 @@ static long linereq_set_config_unlocked(struct linereq *lr,
 			(!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) !=
 			 ((flags & GPIO_V2_LINE_FLAG_ACTIVE_LOW) != 0));
 
+		prev_hte_flag = !!test_bit(FLAG_EVENT_CLOCK_HTE, &desc->flags);
+
 		gpio_v2_line_config_flags_to_desc_flags(flags, &desc->flags);
 		/*
 		 * Lines have to be requested explicitly for input
@@ -1138,7 +1319,7 @@ static long linereq_set_config_unlocked(struct linereq *lr,
 		if (flags & GPIO_V2_LINE_FLAG_OUTPUT) {
 			int val = gpio_v2_line_config_output_value(lc, i);
 
-			edge_detector_stop(&lr->lines[i]);
+			edge_detector_stop(&lr->lines[i], prev_hte_flag);
 			ret = gpiod_direction_output(desc, val);
 			if (ret)
 				return ret;
@@ -1148,8 +1329,7 @@ static long linereq_set_config_unlocked(struct linereq *lr,
 				return ret;
 
 			ret = edge_detector_update(&lr->lines[i], lc, i,
-					flags & GPIO_V2_LINE_EDGE_FLAGS,
-					polarity_change);
+					flags, polarity_change, prev_hte_flag);
 			if (ret)
 				return ret;
 		}
@@ -1280,9 +1460,12 @@ static ssize_t linereq_read(struct file *file,
 static void linereq_free(struct linereq *lr)
 {
 	unsigned int i;
+	bool hte;
 
 	for (i = 0; i < lr->num_lines; i++) {
-		edge_detector_stop(&lr->lines[i]);
+		hte = !!test_bit(FLAG_EVENT_CLOCK_HTE,
+				 &lr->lines[i].desc->flags);
+		edge_detector_stop(&lr->lines[i], hte);
 		if (lr->lines[i].desc)
 			gpiod_free(lr->lines[i].desc);
 	}
@@ -1408,7 +1591,8 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip)
 				goto out_free_linereq;
 
 			ret = edge_detector_setup(&lr->lines[i], lc, i,
-					flags & GPIO_V2_LINE_EDGE_FLAGS);
+				flags & GPIO_V2_LINE_EDGE_FLAGS,
+				flags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE);
 			if (ret)
 				goto out_free_linereq;
 		}
@@ -1961,6 +2145,8 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 
 	if (test_bit(FLAG_EVENT_CLOCK_REALTIME, &desc->flags))
 		info->flags |= GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME;
+	else if (test_bit(FLAG_EVENT_CLOCK_HTE, &desc->flags))
+		info->flags |= GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE;
 
 	debounce_period_us = READ_ONCE(desc->debounce_period_us);
 	if (debounce_period_us) {

drivers/gpio/gpiolib.c

@@ -2453,6 +2453,64 @@ int gpiod_direction_output(struct gpio_desc *desc, int value)
 }
 EXPORT_SYMBOL_GPL(gpiod_direction_output);
 
+/**
+ * gpiod_enable_hw_timestamp_ns - Enable hardware timestamp in nanoseconds.
+ *
+ * @desc: GPIO to enable.
+ * @flags: Flags related to GPIO edge.
+ *
+ * Return 0 in case of success, else negative error code.
+ */
+int gpiod_enable_hw_timestamp_ns(struct gpio_desc *desc, unsigned long flags)
+{
+	int ret = 0;
+	struct gpio_chip *gc;
+
+	VALIDATE_DESC(desc);
+
+	gc = desc->gdev->chip;
+	if (!gc->en_hw_timestamp) {
+		gpiod_warn(desc, "%s: hw ts not supported\n", __func__);
+		return -ENOTSUPP;
+	}
+
+	ret = gc->en_hw_timestamp(gc, gpio_chip_hwgpio(desc), flags);
+	if (ret)
+		gpiod_warn(desc, "%s: hw ts request failed\n", __func__);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gpiod_enable_hw_timestamp_ns);
+
+/**
+ * gpiod_disable_hw_timestamp_ns - Disable hardware timestamp.
+ *
+ * @desc: GPIO to disable.
+ * @flags: Flags related to GPIO edge, same value as used during enable call.
+ *
+ * Return 0 in case of success, else negative error code.
+ */
+int gpiod_disable_hw_timestamp_ns(struct gpio_desc *desc, unsigned long flags)
+{
+	int ret = 0;
+	struct gpio_chip *gc;
+
+	VALIDATE_DESC(desc);
+
+	gc = desc->gdev->chip;
+	if (!gc->dis_hw_timestamp) {
+		gpiod_warn(desc, "%s: hw ts not supported\n", __func__);
+		return -ENOTSUPP;
+	}
+
+	ret = gc->dis_hw_timestamp(gc, gpio_chip_hwgpio(desc), flags);
+	if (ret)
+		gpiod_warn(desc, "%s: hw ts release failed\n", __func__);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gpiod_disable_hw_timestamp_ns);
+
 /**
  * gpiod_set_config - sets @config for a GPIO
  * @desc: descriptor of the GPIO for which to set the configuration

drivers/gpio/gpiolib.h

@@ -161,6 +161,7 @@ struct gpio_desc {
 #define FLAG_EDGE_RISING     16	/* GPIO CDEV detects rising edge events */
 #define FLAG_EDGE_FALLING    17	/* GPIO CDEV detects falling edge events */
 #define FLAG_EVENT_CLOCK_REALTIME	18 /* GPIO CDEV reports REALTIME timestamps in events */
+#define FLAG_EVENT_CLOCK_HTE		19 /* GPIO CDEV reports hardware timestamps in events */
 
 	/* Connection label */
 	const char		*label;

drivers/hte/Kconfig

+# SPDX-License-Identifier: GPL-2.0-only
+menuconfig HTE
+	bool "Hardware Timestamping Engine (HTE) Support"
+	help
+	  Hardware Timestamping Engine (HTE) Support.
+
+	  Some devices provide a hardware timestamping engine which can
+	  timestamp certain device lines/signals in realtime. It comes with a
+	  benefit for the applications needing accurate timestamping event with
+	  less jitter. This framework provides a generic interface to such HTE
+	  providers and consumer devices.
+
+	  If unsure, say no.
+
+if HTE
+
+config HTE_TEGRA194
+	tristate "NVIDIA Tegra194 HTE Support"
+	depends on ARCH_TEGRA_194_SOC
+	help
+	  Enable this option for integrated hardware timestamping engine also
+	  known as generic timestamping engine (GTE) support on NVIDIA Tegra194
+	  systems-on-chip. The driver supports 352 LIC IRQs and 39 AON GPIOs
+	  lines for timestamping in realtime.
+
+config HTE_TEGRA194_TEST
+        tristate "NVIDIA Tegra194 HTE Test"
+        depends on HTE_TEGRA194
+        help
+	  The NVIDIA Tegra194 GTE test driver demonstrates how to use HTE
+	  framework to timestamp GPIO and LIC IRQ lines.
+
+endif

drivers/hte/Makefile

+obj-$(CONFIG_HTE)		+= hte.o
+obj-$(CONFIG_HTE_TEGRA194)	+= hte-tegra194.o
+obj-$(CONFIG_HTE_TEGRA194_TEST) += hte-tegra194-test.o

drivers/hte/hte-tegra194-test.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2021-2022 NVIDIA Corporation
+ *
+ * Author: Dipen Patel <dipenp@nvidia.com>
+ */
+
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/interrupt.h>
+#include <linux/gpio.h>
+#include <linux/timer.h>
+#include <linux/platform_device.h>
+#include <linux/workqueue.h>
+#include <linux/hte.h>
+
+/*
+ * This sample HTE GPIO test driver demonstrates HTE API usage by enabling
+ * hardware timestamp on gpio_in and specified LIC IRQ lines.
+ *
+ * Note: gpio_out and gpio_in need to be shorted externally in order for this
+ * test driver to work for the GPIO monitoring. The test driver has been
+ * tested on Jetson AGX Xavier platform by shorting pin 32 and 16 on 40 pin
+ * header.
+ *
+ * Device tree snippet to activate this driver:
+ *	tegra_hte_test {
+ *		compatible = "nvidia,tegra194-hte-test";
+ *		in-gpio = <&gpio_aon TEGRA194_AON_GPIO(BB, 1)>;
+ *		out-gpio = <&gpio_aon TEGRA194_AON_GPIO(BB, 0)>;
+ *		timestamps = <&tegra_hte_aon TEGRA194_AON_GPIO(BB, 1)>,
+ *			     <&tegra_hte_lic 0x19>;
+ *		timestamp-names = "hte-gpio", "hte-i2c-irq";
+ *		status = "okay";
+ *	};
+ *
+ * How to run test driver:
+ * - Load test driver.
+ * - For the GPIO, at regular interval gpio_out pin toggles triggering
+ *   HTE for rising edge on gpio_in pin.
+ *
+ * - For the LIC IRQ line, it uses 0x19 interrupt which is i2c controller 1.
+ * - Run i2cdetect -y 1 1>/dev/null, this command will generate i2c bus
+ *   transactions which creates timestamp data.
+ * - It prints below message for both the lines.
+ *   HW timestamp(<line id>:<ts seq number>): <timestamp>, edge: <edge>.
+ * - Unloading the driver disables and deallocate the HTE.
+ */
+
+static struct tegra_hte_test {
+	int gpio_in_irq;
+	struct device *pdev;
+	struct gpio_desc *gpio_in;
+	struct gpio_desc *gpio_out;
+	struct hte_ts_desc *desc;
+	struct timer_list timer;
+	struct kobject *kobj;
+} hte;
+
+static enum hte_return process_hw_ts(struct hte_ts_data *ts, void *p)
+{
+	char *edge;
+	struct hte_ts_desc *desc = p;
+
+	if (!ts || !p)
+		return HTE_CB_HANDLED;
+
+	if (ts->raw_level < 0)
+		edge = "Unknown";
+
+	pr_info("HW timestamp(%u: %llu): %llu, edge: %s\n",
+		desc->attr.line_id, ts->seq, ts->tsc,
+		(ts->raw_level >= 0) ? ((ts->raw_level == 0) ?
+					"falling" : "rising") : edge);
+
+	return HTE_CB_HANDLED;
+}
+
+static void gpio_timer_cb(struct timer_list *t)
+{
+	(void)t;
+
+	gpiod_set_value(hte.gpio_out, !gpiod_get_value(hte.gpio_out));
+	mod_timer(&hte.timer, jiffies + msecs_to_jiffies(8000));
+}
+
+static irqreturn_t tegra_hte_test_gpio_isr(int irq, void *data)
+{
+	(void)irq;
+	(void)data;
+
+	return IRQ_HANDLED;
+}
+
+static const struct of_device_id tegra_hte_test_of_match[] = {
+	{ .compatible = "nvidia,tegra194-hte-test"},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, tegra_hte_test_of_match);
+
+static int tegra_hte_test_probe(struct platform_device *pdev)
+{
+	int ret = 0;
+	int i, cnt;
+
+	dev_set_drvdata(&pdev->dev, &hte);
+	hte.pdev = &pdev->dev;
+
+	hte.gpio_out = gpiod_get(&pdev->dev, "out", 0);
+	if (IS_ERR(hte.gpio_out)) {
+		dev_err(&pdev->dev, "failed to get gpio out\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	hte.gpio_in = gpiod_get(&pdev->dev, "in", 0);
+	if (IS_ERR(hte.gpio_in)) {
+		dev_err(&pdev->dev, "failed to get gpio in\n");
+		ret = -EINVAL;
+		goto free_gpio_out;
+	}
+
+	ret = gpiod_direction_output(hte.gpio_out, 0);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to set output\n");
+		ret = -EINVAL;
+		goto free_gpio_in;
+	}
+
+	ret = gpiod_direction_input(hte.gpio_in);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to set input\n");
+		ret = -EINVAL;
+		goto free_gpio_in;
+	}
+
+	ret = gpiod_to_irq(hte.gpio_in);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to map GPIO to IRQ: %d\n", ret);
+		ret = -ENXIO;
+		goto free_gpio_in;
+	}
+
+	hte.gpio_in_irq = ret;
+	ret = request_irq(ret, tegra_hte_test_gpio_isr,
+			  IRQF_TRIGGER_RISING,
+			  "tegra_hte_gpio_test_isr", &hte);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to acquire IRQ\n");
+		ret = -ENXIO;
+		goto free_irq;
+	}
+
+	cnt = of_hte_req_count(hte.pdev);
+	if (cnt < 0)
+		goto free_irq;
+
+	dev_info(&pdev->dev, "Total requested lines:%d\n", cnt);
+
+	hte.desc = devm_kzalloc(hte.pdev, sizeof(*hte.desc) * cnt, GFP_KERNEL);
+	if (!hte.desc) {
+		ret = -ENOMEM;
+		goto free_irq;
+	}
+
+	for (i = 0; i < cnt; i++) {
+		if (i == 0)
+			/*
+			 * GPIO hte init, line_id and name will be parsed from
+			 * the device tree node. The edge_flag is implicitly
+			 * set by request_irq call. Only line_data is needed to be
+			 * set.
+			 */
+			hte_init_line_attr(&hte.desc[i], 0, 0, NULL,
+					   hte.gpio_in);
+		else
+			/*
+			 * same comment as above except that IRQ does not need
+			 * line data.
+			 */
+			hte_init_line_attr(&hte.desc[i], 0, 0, NULL, NULL);
+
+		ret = hte_ts_get(hte.pdev, &hte.desc[i], i);
+		if (ret)
+			goto ts_put;
+
+		ret = devm_hte_request_ts_ns(hte.pdev, &hte.desc[i],
+					     process_hw_ts, NULL,
+					     &hte.desc[i]);
+		if (ret) /* no need to ts_put, request API takes care */
+			goto free_irq;
+	}
+
+	timer_setup(&hte.timer, gpio_timer_cb, 0);
+	mod_timer(&hte.timer, jiffies + msecs_to_jiffies(5000));
+
+	return 0;
+
+ts_put:
+	cnt = i;
+	for (i = 0; i < cnt; i++)
+		hte_ts_put(&hte.desc[i]);
+free_irq:
+	free_irq(hte.gpio_in_irq, &hte);
+free_gpio_in:
+	gpiod_put(hte.gpio_in);
+free_gpio_out:
+	gpiod_put(hte.gpio_out);
+out:
+
+	return ret;
+}
+
+static int tegra_hte_test_remove(struct platform_device *pdev)
+{
+	(void)pdev;
+
+	free_irq(hte.gpio_in_irq, &hte);
+	gpiod_put(hte.gpio_in);
+	gpiod_put(hte.gpio_out);
+	del_timer_sync(&hte.timer);
+
+	return 0;
+}
+
+static struct platform_driver tegra_hte_test_driver = {
+	.probe = tegra_hte_test_probe,
+	.remove = tegra_hte_test_remove,
+	.driver = {
+		.name = "tegra_hte_test",
+		.of_match_table = tegra_hte_test_of_match,
+	},
+};
+module_platform_driver(tegra_hte_test_driver);
+
+MODULE_AUTHOR("Dipen Patel <dipenp@nvidia.com>");
+MODULE_LICENSE("GPL");

drivers/hte/hte-tegra194.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2021-2022 NVIDIA Corporation
+ *
+ * Author: Dipen Patel <dipenp@nvidia.com>
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/stat.h>
+#include <linux/interrupt.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/hte.h>
+#include <linux/uaccess.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/consumer.h>
+
+#define HTE_SUSPEND	0
+
+/* HTE source clock TSC is 31.25MHz */
+#define HTE_TS_CLK_RATE_HZ	31250000ULL
+#define HTE_CLK_RATE_NS		32
+#define HTE_TS_NS_SHIFT	__builtin_ctz(HTE_CLK_RATE_NS)
+
+#define NV_AON_SLICE_INVALID	-1
+#define NV_LINES_IN_SLICE	32
+
+/* AON HTE line map For slice 1 */
+#define NV_AON_HTE_SLICE1_IRQ_GPIO_28	12
+#define NV_AON_HTE_SLICE1_IRQ_GPIO_29	13
+
+/* AON HTE line map For slice 2 */
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_0	0
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_1	1
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_2	2
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_3	3
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_4	4
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_5	5
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_6	6
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_7	7
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_8	8
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_9	9
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_10	10
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_11	11
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_12	12
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_13	13
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_14	14
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_15	15
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_16	16
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_17	17
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_18	18
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_19	19
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_20	20
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_21	21
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_22	22
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_23	23
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_24	24
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_25	25
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_26	26
+#define NV_AON_HTE_SLICE2_IRQ_GPIO_27	27
+
+#define HTE_TECTRL		0x0
+#define HTE_TETSCH		0x4
+#define HTE_TETSCL		0x8
+#define HTE_TESRC		0xC
+#define HTE_TECCV		0x10
+#define HTE_TEPCV		0x14
+#define HTE_TECMD		0x1C
+#define HTE_TESTATUS		0x20
+#define HTE_SLICE0_TETEN	0x40
+#define HTE_SLICE1_TETEN	0x60
+
+#define HTE_SLICE_SIZE		(HTE_SLICE1_TETEN - HTE_SLICE0_TETEN)
+
+#define HTE_TECTRL_ENABLE_ENABLE	0x1
+
+#define HTE_TECTRL_OCCU_SHIFT		0x8
+#define HTE_TECTRL_INTR_SHIFT		0x1
+#define HTE_TECTRL_INTR_ENABLE		0x1
+
+#define HTE_TESRC_SLICE_SHIFT		16
+#define HTE_TESRC_SLICE_DEFAULT_MASK	0xFF
+
+#define HTE_TECMD_CMD_POP		0x1
+
+#define HTE_TESTATUS_OCCUPANCY_SHIFT	8
+#define HTE_TESTATUS_OCCUPANCY_MASK	0xFF
+
+enum tegra_hte_type {
+	HTE_TEGRA_TYPE_GPIO = 1U << 0,
+	HTE_TEGRA_TYPE_LIC = 1U << 1,
+};
+
+struct hte_slices {
+	u32 r_val;
+	unsigned long flags;
+	/* to prevent lines mapped to same slice updating its register */
+	spinlock_t s_lock;
+};
+
+struct tegra_hte_line_mapped {
+	int slice;
+	u32 bit_index;
+};
+
+struct tegra_hte_line_data {
+	unsigned long flags;
+	void *data;
+};
+
+struct tegra_hte_data {
+	enum tegra_hte_type type;
+	u32 map_sz;
+	u32 sec_map_sz;
+	const struct tegra_hte_line_mapped *map;
+	const struct tegra_hte_line_mapped *sec_map;
+};
+
+struct tegra_hte_soc {
+	int hte_irq;
+	u32 itr_thrshld;
+	u32 conf_rval;
+	struct hte_slices *sl;
+	const struct tegra_hte_data *prov_data;
+	struct tegra_hte_line_data *line_data;
+	struct hte_chip *chip;
+	struct gpio_chip *c;
+	void __iomem *regs;
+};
+
+static const struct tegra_hte_line_mapped tegra194_aon_gpio_map[] = {
+	/* gpio, slice, bit_index */
+	/* AA port */
+	[0]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_11},
+	[1]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_10},
+	[2]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_9},
+	[3]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_8},
+	[4]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_7},
+	[5]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_6},
+	[6]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_5},
+	[7]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_4},
+	/* BB port */
+	[8]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_3},
+	[9]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_2},
+	[10] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_1},
+	[11] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_0},
+	/* CC port */
+	[12] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_22},
+	[13] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_21},
+	[14] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_20},
+	[15] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_19},
+	[16] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_18},
+	[17] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_17},
+	[18] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_16},
+	[19] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_15},
+	/* DD port */
+	[20] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_14},
+	[21] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_13},
+	[22] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_12},
+	/* EE port */
+	[23] = {1, NV_AON_HTE_SLICE1_IRQ_GPIO_29},
+	[24] = {1, NV_AON_HTE_SLICE1_IRQ_GPIO_28},
+	[25] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_27},
+	[26] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_26},
+	[27] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_25},
+	[28] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_24},
+	[29] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_23},
+};
+
+static const struct tegra_hte_line_mapped tegra194_aon_gpio_sec_map[] = {
+	/* gpio, slice, bit_index */
+	/* AA port */
+	[0]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_11},
+	[1]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_10},
+	[2]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_9},
+	[3]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_8},
+	[4]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_7},
+	[5]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_6},
+	[6]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_5},
+	[7]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_4},
+	/* BB port */
+	[8]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_3},
+	[9]  = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_2},
+	[10] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_1},
+	[11] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_0},
+	[12]  = {NV_AON_SLICE_INVALID, 0},
+	[13]  = {NV_AON_SLICE_INVALID, 0},
+	[14] = {NV_AON_SLICE_INVALID, 0},
+	[15] = {NV_AON_SLICE_INVALID, 0},
+	/* CC port */
+	[16] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_22},
+	[17] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_21},
+	[18] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_20},
+	[19] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_19},
+	[20] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_18},
+	[21] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_17},
+	[22] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_16},
+	[23] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_15},
+	/* DD port */
+	[24] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_14},
+	[25] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_13},
+	[26] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_12},
+	[27] = {NV_AON_SLICE_INVALID, 0},
+	[28] = {NV_AON_SLICE_INVALID, 0},
+	[29] = {NV_AON_SLICE_INVALID, 0},
+	[30] = {NV_AON_SLICE_INVALID, 0},
+	[31] = {NV_AON_SLICE_INVALID, 0},
+	/* EE port */
+	[32] = {1, NV_AON_HTE_SLICE1_IRQ_GPIO_29},
+	[33] = {1, NV_AON_HTE_SLICE1_IRQ_GPIO_28},
+	[34] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_27},
+	[35] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_26},
+	[36] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_25},
+	[37] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_24},
+	[38] = {2, NV_AON_HTE_SLICE2_IRQ_GPIO_23},
+	[39] = {NV_AON_SLICE_INVALID, 0},
+};
+
+static const struct tegra_hte_data aon_hte = {
+	.map_sz = ARRAY_SIZE(tegra194_aon_gpio_map),
+	.map = tegra194_aon_gpio_map,
+	.sec_map_sz = ARRAY_SIZE(tegra194_aon_gpio_sec_map),
+	.sec_map = tegra194_aon_gpio_sec_map,
+	.type = HTE_TEGRA_TYPE_GPIO,
+};
+
+static const struct tegra_hte_data lic_hte = {
+	.map_sz = 0,
+	.map = NULL,
+	.type = HTE_TEGRA_TYPE_LIC,
+};
+
+static inline u32 tegra_hte_readl(struct tegra_hte_soc *hte, u32 reg)
+{
+	return readl(hte->regs + reg);
+}
+
+static inline void tegra_hte_writel(struct tegra_hte_soc *hte, u32 reg,
+				    u32 val)
+{
+	writel(val, hte->regs + reg);
+}
+
+static int tegra_hte_map_to_line_id(u32 eid,
+				    const struct tegra_hte_line_mapped *m,
+				    u32 map_sz, u32 *mapped)
+{
+
+	if (m) {
+		if (eid > map_sz)
+			return -EINVAL;
+		if (m[eid].slice == NV_AON_SLICE_INVALID)
+			return -EINVAL;
+
+		*mapped = (m[eid].slice << 5) + m[eid].bit_index;
+	} else {
+		*mapped = eid;
+	}
+
+	return 0;
+}
+
+static int tegra_hte_line_xlate(struct hte_chip *gc,
+				const struct of_phandle_args *args,
+				struct hte_ts_desc *desc, u32 *xlated_id)
+{
+	int ret = 0;
+	u32 line_id;
+	struct tegra_hte_soc *gs;
+	const struct tegra_hte_line_mapped *map = NULL;
+	u32 map_sz = 0;
+
+	if (!gc || !desc || !xlated_id)
+		return -EINVAL;
+
+	if (args) {
+		if (gc->of_hte_n_cells < 1)
+			return -EINVAL;
+
+		if (args->args_count != gc->of_hte_n_cells)
+			return -EINVAL;
+
+		desc->attr.line_id = args->args[0];
+	}
+
+	gs = gc->data;
+	if (!gs || !gs->prov_data)
+		return -EINVAL;
+
+	/*
+	 *
+	 * There are two paths GPIO consumers can take as follows:
+	 * 1) The consumer (gpiolib-cdev for example) which uses GPIO global
+	 * number which gets assigned run time.
+	 * 2) The consumer passing GPIO from the DT which is assigned
+	 * statically for example by using TEGRA194_AON_GPIO gpio DT binding.
+	 *
+	 * The code below addresses both the consumer use cases and maps into
+	 * HTE/GTE namespace.
+	 */
+	if (gs->prov_data->type == HTE_TEGRA_TYPE_GPIO && !args) {
+		line_id = desc->attr.line_id - gs->c->base;
+		map = gs->prov_data->map;
+		map_sz = gs->prov_data->map_sz;
+	} else if (gs->prov_data->type == HTE_TEGRA_TYPE_GPIO && args) {
+		line_id = desc->attr.line_id;
+		map = gs->prov_data->sec_map;
+		map_sz = gs->prov_data->sec_map_sz;
+	} else {
+		line_id = desc->attr.line_id;
+	}
+
+	ret = tegra_hte_map_to_line_id(line_id, map, map_sz, xlated_id);
+	if (ret < 0) {
+		dev_err(gc->dev, "line_id:%u mapping failed\n",
+			desc->attr.line_id);
+		return ret;
+	}
+
+	if (*xlated_id > gc->nlines)
+		return -EINVAL;
+
+	dev_dbg(gc->dev, "requested id:%u, xlated id:%u\n",
+		desc->attr.line_id, *xlated_id);
+
+	return 0;
+}
+
+static int tegra_hte_line_xlate_plat(struct hte_chip *gc,
+				     struct hte_ts_desc *desc, u32 *xlated_id)
+{
+	return tegra_hte_line_xlate(gc, NULL, desc, xlated_id);
+}
+
+static int tegra_hte_en_dis_common(struct hte_chip *chip, u32 line_id, bool en)
+{
+	u32 slice, sl_bit_shift, line_bit, val, reg;
+	struct tegra_hte_soc *gs;
+
+	sl_bit_shift = __builtin_ctz(HTE_SLICE_SIZE);
+
+	if (!chip)
+		return -EINVAL;
+
+	gs = chip->data;
+
+	if (line_id > chip->nlines) {
+		dev_err(chip->dev,
+			"line id: %u is not supported by this controller\n",
+			line_id);
+		return -EINVAL;
+	}
+
+	slice = line_id >> sl_bit_shift;
+	line_bit = line_id & (HTE_SLICE_SIZE - 1);
+	reg = (slice << sl_bit_shift) + HTE_SLICE0_TETEN;
+
+	spin_lock(&gs->sl[slice].s_lock);
+
+	if (test_bit(HTE_SUSPEND, &gs->sl[slice].flags)) {
+		spin_unlock(&gs->sl[slice].s_lock);
+		dev_dbg(chip->dev, "device suspended");
+		return -EBUSY;
+	}
+
+	val = tegra_hte_readl(gs, reg);
+	if (en)
+		val = val | (1 << line_bit);
+	else
+		val = val & (~(1 << line_bit));
+	tegra_hte_writel(gs, reg, val);
+
+	spin_unlock(&gs->sl[slice].s_lock);
+
+	dev_dbg(chip->dev, "line: %u, slice %u, line_bit %u, reg:0x%x\n",
+		line_id, slice, line_bit, reg);
+
+	return 0;
+}
+
+static int tegra_hte_enable(struct hte_chip *chip, u32 line_id)
+{
+	if (!chip)
+		return -EINVAL;
+
+	return tegra_hte_en_dis_common(chip, line_id, true);
+}
+
+static int tegra_hte_disable(struct hte_chip *chip, u32 line_id)
+{
+	if (!chip)
+		return -EINVAL;
+
+	return tegra_hte_en_dis_common(chip, line_id, false);
+}
+
+static int tegra_hte_request(struct hte_chip *chip, struct hte_ts_desc *desc,
+			     u32 line_id)
+{
+	int ret;
+	struct tegra_hte_soc *gs;
+	struct hte_line_attr *attr;
+
+	if (!chip || !chip->data || !desc)
+		return -EINVAL;
+
+	gs = chip->data;
+	attr = &desc->attr;
+
+	if (gs->prov_data->type == HTE_TEGRA_TYPE_GPIO) {
+		if (!attr->line_data)
+			return -EINVAL;
+
+		ret = gpiod_enable_hw_timestamp_ns(attr->line_data,
+						   attr->edge_flags);
+		if (ret)
+			return ret;
+
+		gs->line_data[line_id].data = attr->line_data;
+		gs->line_data[line_id].flags = attr->edge_flags;
+	}
+
+	return tegra_hte_en_dis_common(chip, line_id, true);
+}
+
+static int tegra_hte_release(struct hte_chip *chip, struct hte_ts_desc *desc,
+			     u32 line_id)
+{
+	struct tegra_hte_soc *gs;
+	struct hte_line_attr *attr;
+	int ret;
+
+	if (!chip || !chip->data || !desc)
+		return -EINVAL;
+
+	gs = chip->data;
+	attr = &desc->attr;
+
+	if (gs->prov_data->type == HTE_TEGRA_TYPE_GPIO) {
+		ret = gpiod_disable_hw_timestamp_ns(attr->line_data,
+						    gs->line_data[line_id].flags);
+		if (ret)
+			return ret;
+
+		gs->line_data[line_id].data = NULL;
+		gs->line_data[line_id].flags = 0;
+	}
+
+	return tegra_hte_en_dis_common(chip, line_id, false);
+}
+
+static int tegra_hte_clk_src_info(struct hte_chip *chip,
+				  struct hte_clk_info *ci)
+{
+	(void)chip;
+
+	if (!ci)
+		return -EINVAL;
+
+	ci->hz = HTE_TS_CLK_RATE_HZ;
+	ci->type = CLOCK_MONOTONIC;
+
+	return 0;
+}
+
+static int tegra_hte_get_level(struct tegra_hte_soc *gs, u32 line_id)
+{
+	struct gpio_desc *desc;
+
+	if (gs->prov_data->type == HTE_TEGRA_TYPE_GPIO) {
+		desc = gs->line_data[line_id].data;
+		if (desc)
+			return gpiod_get_raw_value(desc);
+	}
+
+	return -1;
+}
+
+static void tegra_hte_read_fifo(struct tegra_hte_soc *gs)
+{
+	u32 tsh, tsl, src, pv, cv, acv, slice, bit_index, line_id;
+	u64 tsc;
+	struct hte_ts_data el;
+
+	while ((tegra_hte_readl(gs, HTE_TESTATUS) >>
+		HTE_TESTATUS_OCCUPANCY_SHIFT) &
+		HTE_TESTATUS_OCCUPANCY_MASK) {
+		tsh = tegra_hte_readl(gs, HTE_TETSCH);
+		tsl = tegra_hte_readl(gs, HTE_TETSCL);
+		tsc = (((u64)tsh << 32) | tsl);
+
+		src = tegra_hte_readl(gs, HTE_TESRC);
+		slice = (src >> HTE_TESRC_SLICE_SHIFT) &
+			    HTE_TESRC_SLICE_DEFAULT_MASK;
+
+		pv = tegra_hte_readl(gs, HTE_TEPCV);
+		cv = tegra_hte_readl(gs, HTE_TECCV);
+		acv = pv ^ cv;
+		while (acv) {
+			bit_index = __builtin_ctz(acv);
+			line_id = bit_index + (slice << 5);
+			el.tsc = tsc << HTE_TS_NS_SHIFT;
+			el.raw_level = tegra_hte_get_level(gs, line_id);
+			hte_push_ts_ns(gs->chip, line_id, &el);
+			acv &= ~BIT(bit_index);
+		}
+		tegra_hte_writel(gs, HTE_TECMD, HTE_TECMD_CMD_POP);
+	}
+}
+
+static irqreturn_t tegra_hte_isr(int irq, void *dev_id)
+{
+	struct tegra_hte_soc *gs = dev_id;
+	(void)irq;
+
+	tegra_hte_read_fifo(gs);
+
+	return IRQ_HANDLED;
+}
+
+static bool tegra_hte_match_from_linedata(const struct hte_chip *chip,
+					  const struct hte_ts_desc *hdesc)
+{
+	struct tegra_hte_soc *hte_dev = chip->data;
+
+	if (!hte_dev || (hte_dev->prov_data->type != HTE_TEGRA_TYPE_GPIO))
+		return false;
+
+	return hte_dev->c == gpiod_to_chip(hdesc->attr.line_data);
+}
+
+static const struct of_device_id tegra_hte_of_match[] = {
+	{ .compatible = "nvidia,tegra194-gte-lic", .data = &lic_hte},
+	{ .compatible = "nvidia,tegra194-gte-aon", .data = &aon_hte},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, tegra_hte_of_match);
+
+static const struct hte_ops g_ops = {
+	.request = tegra_hte_request,
+	.release = tegra_hte_release,
+	.enable = tegra_hte_enable,
+	.disable = tegra_hte_disable,
+	.get_clk_src_info = tegra_hte_clk_src_info,
+};
+
+static void tegra_gte_disable(void *data)
+{
+	struct platform_device *pdev = data;
+	struct tegra_hte_soc *gs = dev_get_drvdata(&pdev->dev);
+
+	tegra_hte_writel(gs, HTE_TECTRL, 0);
+}
+
+static int tegra_get_gpiochip_from_name(struct gpio_chip *chip, void *data)
+{
+	return !strcmp(chip->label, data);
+}
+
+static int tegra_hte_probe(struct platform_device *pdev)
+{
+	int ret;
+	u32 i, slices, val = 0;
+	u32 nlines;
+	struct device *dev;
+	struct tegra_hte_soc *hte_dev;
+	struct hte_chip *gc;
+
+	dev = &pdev->dev;
+
+	ret = of_property_read_u32(dev->of_node, "nvidia,slices", &slices);
+	if (ret != 0) {
+		dev_err(dev, "Could not read slices\n");
+		return -EINVAL;
+	}
+	nlines = slices << 5;
+
+	hte_dev = devm_kzalloc(dev, sizeof(*hte_dev), GFP_KERNEL);
+	if (!hte_dev)
+		return -ENOMEM;
+
+	gc = devm_kzalloc(dev, sizeof(*gc), GFP_KERNEL);
+	if (!gc)
+		return -ENOMEM;
+
+	dev_set_drvdata(&pdev->dev, hte_dev);
+	hte_dev->prov_data = of_device_get_match_data(&pdev->dev);
+
+	hte_dev->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(hte_dev->regs))
+		return PTR_ERR(hte_dev->regs);
+
+	ret = of_property_read_u32(dev->of_node, "nvidia,int-threshold",
+				   &hte_dev->itr_thrshld);
+	if (ret != 0)
+		hte_dev->itr_thrshld = 1;
+
+	hte_dev->sl = devm_kcalloc(dev, slices, sizeof(*hte_dev->sl),
+				   GFP_KERNEL);
+	if (!hte_dev->sl)
+		return -ENOMEM;
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0) {
+		dev_err_probe(dev, ret, "failed to get irq\n");
+		return ret;
+	}
+	hte_dev->hte_irq = ret;
+	ret = devm_request_irq(dev, hte_dev->hte_irq, tegra_hte_isr, 0,
+			       dev_name(dev), hte_dev);
+	if (ret < 0) {
+		dev_err(dev, "request irq failed.\n");
+		return ret;
+	}
+
+	gc->nlines = nlines;
+	gc->ops = &g_ops;
+	gc->dev = dev;
+	gc->data = hte_dev;
+	gc->xlate_of = tegra_hte_line_xlate;
+	gc->xlate_plat = tegra_hte_line_xlate_plat;
+	gc->of_hte_n_cells = 1;
+
+	if (hte_dev->prov_data &&
+	    hte_dev->prov_data->type == HTE_TEGRA_TYPE_GPIO) {
+		hte_dev->line_data = devm_kcalloc(dev, nlines,
+						  sizeof(*hte_dev->line_data),
+						  GFP_KERNEL);
+		if (!hte_dev->line_data)
+			return -ENOMEM;
+
+		gc->match_from_linedata = tegra_hte_match_from_linedata;
+
+		hte_dev->c = gpiochip_find("tegra194-gpio-aon",
+					   tegra_get_gpiochip_from_name);
+		if (!hte_dev->c)
+			return dev_err_probe(dev, -EPROBE_DEFER,
+					     "wait for gpio controller\n");
+	}
+
+	hte_dev->chip = gc;
+
+	ret = devm_hte_register_chip(hte_dev->chip);
+	if (ret) {
+		dev_err(gc->dev, "hte chip register failed");
+		return ret;
+	}
+
+	for (i = 0; i < slices; i++) {
+		hte_dev->sl[i].flags = 0;
+		spin_lock_init(&hte_dev->sl[i].s_lock);
+	}
+
+	val = HTE_TECTRL_ENABLE_ENABLE |
+	      (HTE_TECTRL_INTR_ENABLE << HTE_TECTRL_INTR_SHIFT) |
+	      (hte_dev->itr_thrshld << HTE_TECTRL_OCCU_SHIFT);
+	tegra_hte_writel(hte_dev, HTE_TECTRL, val);
+
+	ret = devm_add_action_or_reset(&pdev->dev, tegra_gte_disable, pdev);
+	if (ret)
+		return ret;
+
+	dev_dbg(gc->dev, "lines: %d, slices:%d", gc->nlines, slices);
+
+	return 0;
+}
+
+static int __maybe_unused tegra_hte_resume_early(struct device *dev)
+{
+	u32 i;
+	struct tegra_hte_soc *gs = dev_get_drvdata(dev);
+	u32 slices = gs->chip->nlines / NV_LINES_IN_SLICE;
+	u32 sl_bit_shift = __builtin_ctz(HTE_SLICE_SIZE);
+
+	tegra_hte_writel(gs, HTE_TECTRL, gs->conf_rval);
+
+	for (i = 0; i < slices; i++) {
+		spin_lock(&gs->sl[i].s_lock);
+		tegra_hte_writel(gs,
+				 ((i << sl_bit_shift) + HTE_SLICE0_TETEN),
+				 gs->sl[i].r_val);
+		clear_bit(HTE_SUSPEND, &gs->sl[i].flags);
+		spin_unlock(&gs->sl[i].s_lock);
+	}
+
+	return 0;
+}
+
+static int __maybe_unused tegra_hte_suspend_late(struct device *dev)
+{
+	u32 i;
+	struct tegra_hte_soc *gs = dev_get_drvdata(dev);
+	u32 slices = gs->chip->nlines / NV_LINES_IN_SLICE;
+	u32 sl_bit_shift = __builtin_ctz(HTE_SLICE_SIZE);
+
+	gs->conf_rval = tegra_hte_readl(gs, HTE_TECTRL);
+	for (i = 0; i < slices; i++) {
+		spin_lock(&gs->sl[i].s_lock);
+		gs->sl[i].r_val = tegra_hte_readl(gs,
+				((i << sl_bit_shift) + HTE_SLICE0_TETEN));
+		set_bit(HTE_SUSPEND, &gs->sl[i].flags);
+		spin_unlock(&gs->sl[i].s_lock);
+	}
+
+	return 0;
+}
+
+static const struct dev_pm_ops tegra_hte_pm = {
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(tegra_hte_suspend_late,
+				     tegra_hte_resume_early)
+};
+
+static struct platform_driver tegra_hte_driver = {
+	.probe = tegra_hte_probe,
+	.driver = {
+		.name = "tegra_hte",
+		.pm = &tegra_hte_pm,
+		.of_match_table = tegra_hte_of_match,
+	},
+};
+
+module_platform_driver(tegra_hte_driver);
+
+MODULE_AUTHOR("Dipen Patel <dipenp@nvidia.com>");
+MODULE_DESCRIPTION("NVIDIA Tegra HTE (Hardware Timestamping Engine) driver");
+MODULE_LICENSE("GPL");

drivers/hte/hte.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2021-2022 NVIDIA Corporation
+ *
+ * Author: Dipen Patel <dipenp@nvidia.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/mutex.h>
+#include <linux/uaccess.h>
+#include <linux/hte.h>
+#include <linux/delay.h>
+#include <linux/debugfs.h>
+
+#define HTE_TS_NAME_LEN		10
+
+/* Global list of the HTE devices */
+static DEFINE_SPINLOCK(hte_lock);
+static LIST_HEAD(hte_devices);
+
+enum {
+	HTE_TS_REGISTERED,
+	HTE_TS_REQ,
+	HTE_TS_DISABLE,
+	HTE_TS_QUEUE_WK,
+};
+
+/**
+ * struct hte_ts_info - Information related to requested timestamp.
+ *
+ * @xlated_id: Timestamp ID as understood between HTE subsys and HTE provider,
+ * See xlate callback API.
+ * @flags: Flags holding state information.
+ * @hte_cb_flags: Callback related flags.
+ * @seq: Timestamp sequence counter.
+ * @line_name: HTE allocated line name.
+ * @free_attr_name: If set, free the attr name.
+ * @cb: A nonsleeping callback function provided by clients.
+ * @tcb: A secondary sleeping callback function provided by clients.
+ * @dropped_ts: Dropped timestamps.
+ * @slock: Spin lock to synchronize between disable/enable,
+ * request/release APIs.
+ * @cb_work: callback workqueue, used when tcb is specified.
+ * @req_mlock: Lock during timestamp request/release APIs.
+ * @ts_dbg_root: Root for the debug fs.
+ * @gdev: HTE abstract device that this timestamp information belongs to.
+ * @cl_data: Client specific data.
+ */
+struct hte_ts_info {
+	u32 xlated_id;
+	unsigned long flags;
+	unsigned long hte_cb_flags;
+	u64 seq;
+	char *line_name;
+	bool free_attr_name;
+	hte_ts_cb_t cb;
+	hte_ts_sec_cb_t tcb;
+	atomic_t dropped_ts;
+	spinlock_t slock;
+	struct work_struct cb_work;
+	struct mutex req_mlock;
+	struct dentry *ts_dbg_root;
+	struct hte_device *gdev;
+	void *cl_data;
+};
+
+/**
+ * struct hte_device - HTE abstract device
+ * @nlines: Number of entities this device supports.
+ * @ts_req: Total number of entities requested.
+ * @sdev: Device used at various debug prints.
+ * @dbg_root: Root directory for debug fs.
+ * @list: List node to store hte_device for each provider.
+ * @chip: HTE chip providing this HTE device.
+ * @owner: helps prevent removal of modules when in use.
+ * @ei: Timestamp information.
+ */
+struct hte_device {
+	u32 nlines;
+	atomic_t ts_req;
+	struct device *sdev;
+	struct dentry *dbg_root;
+	struct list_head list;
+	struct hte_chip *chip;
+	struct module *owner;
+	struct hte_ts_info ei[];
+};
+
+#ifdef CONFIG_DEBUG_FS
+
+static struct dentry *hte_root;
+
+static int __init hte_subsys_dbgfs_init(void)
+{
+	/* creates /sys/kernel/debug/hte/ */
+	hte_root = debugfs_create_dir("hte", NULL);
+
+	return 0;
+}
+subsys_initcall(hte_subsys_dbgfs_init);
+
+static void hte_chip_dbgfs_init(struct hte_device *gdev)
+{
+	const struct hte_chip *chip = gdev->chip;
+	const char *name = chip->name ? chip->name : dev_name(chip->dev);
+
+	gdev->dbg_root = debugfs_create_dir(name, hte_root);
+
+	debugfs_create_atomic_t("ts_requested", 0444, gdev->dbg_root,
+				&gdev->ts_req);
+	debugfs_create_u32("total_ts", 0444, gdev->dbg_root,
+			   &gdev->nlines);
+}
+
+static void hte_ts_dbgfs_init(const char *name, struct hte_ts_info *ei)
+{
+	if (!ei->gdev->dbg_root || !name)
+		return;
+
+	ei->ts_dbg_root = debugfs_create_dir(name, ei->gdev->dbg_root);
+
+	debugfs_create_atomic_t("dropped_timestamps", 0444, ei->ts_dbg_root,
+				&ei->dropped_ts);
+}
+
+#else
+
+static void hte_chip_dbgfs_init(struct hte_device *gdev)
+{
+}
+
+static void hte_ts_dbgfs_init(const char *name, struct hte_ts_info *ei)
+{
+}
+
+#endif
+
+/**
+ * hte_ts_put() - Release and disable timestamp for the given desc.
+ *
+ * @desc: timestamp descriptor.
+ *
+ * Context: debugfs_remove_recursive() function call may use sleeping locks,
+ *	    not suitable from atomic context.
+ * Returns: 0 on success or a negative error code on failure.
+ */
+int hte_ts_put(struct hte_ts_desc *desc)
+{
+	int ret = 0;
+	unsigned long flag;
+	struct hte_device *gdev;
+	struct hte_ts_info *ei;
+
+	if (!desc)
+		return -EINVAL;
+
+	ei = desc->hte_data;
+
+	if (!ei || !ei->gdev)
+		return -EINVAL;
+
+	gdev = ei->gdev;
+
+	mutex_lock(&ei->req_mlock);
+
+	if (unlikely(!test_bit(HTE_TS_REQ, &ei->flags) &&
+	    !test_bit(HTE_TS_REGISTERED, &ei->flags))) {
+		dev_info(gdev->sdev, "id:%d is not requested\n",
+			 desc->attr.line_id);
+		ret = -EINVAL;
+		goto unlock;
+	}
+
+	if (unlikely(!test_bit(HTE_TS_REQ, &ei->flags) &&
+	    test_bit(HTE_TS_REGISTERED, &ei->flags))) {
+		dev_info(gdev->sdev, "id:%d is registered but not requested\n",
+			 desc->attr.line_id);
+		ret = -EINVAL;
+		goto unlock;
+	}
+
+	if (test_bit(HTE_TS_REQ, &ei->flags) &&
+	    !test_bit(HTE_TS_REGISTERED, &ei->flags)) {
+		clear_bit(HTE_TS_REQ, &ei->flags);
+		desc->hte_data = NULL;
+		ret = 0;
+		goto mod_put;
+	}
+
+	ret = gdev->chip->ops->release(gdev->chip, desc, ei->xlated_id);
+	if (ret) {
+		dev_err(gdev->sdev, "id: %d free failed\n",
+			desc->attr.line_id);
+		goto unlock;
+	}
+
+	kfree(ei->line_name);
+	if (ei->free_attr_name)
+		kfree_const(desc->attr.name);
+
+	debugfs_remove_recursive(ei->ts_dbg_root);
+
+	spin_lock_irqsave(&ei->slock, flag);
+
+	if (test_bit(HTE_TS_QUEUE_WK, &ei->flags)) {
+		spin_unlock_irqrestore(&ei->slock, flag);
+		flush_work(&ei->cb_work);
+		spin_lock_irqsave(&ei->slock, flag);
+	}
+
+	atomic_dec(&gdev->ts_req);
+	atomic_set(&ei->dropped_ts, 0);
+
+	ei->seq = 1;
+	ei->flags = 0;
+	desc->hte_data = NULL;
+
+	spin_unlock_irqrestore(&ei->slock, flag);
+
+	ei->cb = NULL;
+	ei->tcb = NULL;
+	ei->cl_data = NULL;
+
+mod_put:
+	module_put(gdev->owner);
+unlock:
+	mutex_unlock(&ei->req_mlock);
+	dev_dbg(gdev->sdev, "release id: %d\n", desc->attr.line_id);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(hte_ts_put);
+
+static int hte_ts_dis_en_common(struct hte_ts_desc *desc, bool en)
+{
+	u32 ts_id;
+	struct hte_device *gdev;
+	struct hte_ts_info *ei;
+	int ret;
+	unsigned long flag;
+
+	if (!desc)
+		return -EINVAL;
+
+	ei = desc->hte_data;
+
+	if (!ei || !ei->gdev)
+		return -EINVAL;
+
+	gdev = ei->gdev;
+	ts_id = desc->attr.line_id;
+
+	mutex_lock(&ei->req_mlock);
+
+	if (!test_bit(HTE_TS_REGISTERED, &ei->flags)) {
+		dev_dbg(gdev->sdev, "id:%d is not registered", ts_id);
+		ret = -EUSERS;
+		goto out;
+	}
+
+	spin_lock_irqsave(&ei->slock, flag);
+
+	if (en) {
+		if (!test_bit(HTE_TS_DISABLE, &ei->flags)) {
+			ret = 0;
+			goto out_unlock;
+		}
+
+		spin_unlock_irqrestore(&ei->slock, flag);
+		ret = gdev->chip->ops->enable(gdev->chip, ei->xlated_id);
+		if (ret) {
+			dev_warn(gdev->sdev, "id: %d enable failed\n",
+				 ts_id);
+			goto out;
+		}
+
+		spin_lock_irqsave(&ei->slock, flag);
+		clear_bit(HTE_TS_DISABLE, &ei->flags);
+	} else {
+		if (test_bit(HTE_TS_DISABLE, &ei->flags)) {
+			ret = 0;
+			goto out_unlock;
+		}
+
+		spin_unlock_irqrestore(&ei->slock, flag);
+		ret = gdev->chip->ops->disable(gdev->chip, ei->xlated_id);
+		if (ret) {
+			dev_warn(gdev->sdev, "id: %d disable failed\n",
+				 ts_id);
+			goto out;
+		}
+
+		spin_lock_irqsave(&ei->slock, flag);
+		set_bit(HTE_TS_DISABLE, &ei->flags);
+	}
+
+out_unlock:
+	spin_unlock_irqrestore(&ei->slock, flag);
+out:
+	mutex_unlock(&ei->req_mlock);
+	return ret;
+}
+
+/**
+ * hte_disable_ts() - Disable timestamp on given descriptor.
+ *
+ * The API does not release any resources associated with desc.
+ *
+ * @desc: ts descriptor, this is the same as returned by the request API.
+ *
+ * Context: Holds mutex lock, not suitable from atomic context.
+ * Returns: 0 on success or a negative error code on failure.
+ */
+int hte_disable_ts(struct hte_ts_desc *desc)
+{
+	return hte_ts_dis_en_common(desc, false);
+}
+EXPORT_SYMBOL_GPL(hte_disable_ts);
+
+/**
+ * hte_enable_ts() - Enable timestamp on given descriptor.
+ *
+ * @desc: ts descriptor, this is the same as returned by the request API.
+ *
+ * Context: Holds mutex lock, not suitable from atomic context.
+ * Returns: 0 on success or a negative error code on failure.
+ */
+int hte_enable_ts(struct hte_ts_desc *desc)
+{
+	return hte_ts_dis_en_common(desc, true);
+}
+EXPORT_SYMBOL_GPL(hte_enable_ts);
+
+static void hte_do_cb_work(struct work_struct *w)
+{
+	unsigned long flag;
+	struct hte_ts_info *ei = container_of(w, struct hte_ts_info, cb_work);
+
+	if (unlikely(!ei->tcb))
+		return;
+
+	ei->tcb(ei->cl_data);
+
+	spin_lock_irqsave(&ei->slock, flag);
+	clear_bit(HTE_TS_QUEUE_WK, &ei->flags);
+	spin_unlock_irqrestore(&ei->slock, flag);
+}
+
+static int __hte_req_ts(struct hte_ts_desc *desc, hte_ts_cb_t cb,
+			hte_ts_sec_cb_t tcb, void *data)
+{
+	int ret;
+	struct hte_device *gdev;
+	struct hte_ts_info *ei = desc->hte_data;
+
+	gdev = ei->gdev;
+	/*
+	 * There is a chance that multiple consumers requesting same entity,
+	 * lock here.
+	 */
+	mutex_lock(&ei->req_mlock);
+
+	if (test_bit(HTE_TS_REGISTERED, &ei->flags) ||
+	    !test_bit(HTE_TS_REQ, &ei->flags)) {
+		dev_dbg(gdev->chip->dev, "id:%u req failed\n",
+			desc->attr.line_id);
+		ret = -EUSERS;
+		goto unlock;
+	}
+
+	ei->cb = cb;
+	ei->tcb = tcb;
+	if (tcb)
+		INIT_WORK(&ei->cb_work, hte_do_cb_work);
+
+	ret = gdev->chip->ops->request(gdev->chip, desc, ei->xlated_id);
+	if (ret < 0) {
+		dev_err(gdev->chip->dev, "ts request failed\n");
+		goto unlock;
+	}
+
+	ei->cl_data = data;
+	ei->seq = 1;
+
+	atomic_inc(&gdev->ts_req);
+
+	ei->line_name = NULL;
+	if (!desc->attr.name) {
+		ei->line_name = kzalloc(HTE_TS_NAME_LEN, GFP_KERNEL);
+		if (ei->line_name)
+			scnprintf(ei->line_name, HTE_TS_NAME_LEN, "ts_%u",
+				  desc->attr.line_id);
+	}
+
+	hte_ts_dbgfs_init(desc->attr.name == NULL ?
+			  ei->line_name : desc->attr.name, ei);
+	set_bit(HTE_TS_REGISTERED, &ei->flags);
+
+	dev_dbg(gdev->chip->dev, "id: %u, xlated id:%u",
+		desc->attr.line_id, ei->xlated_id);
+
+	ret = 0;
+
+unlock:
+	mutex_unlock(&ei->req_mlock);
+
+	return ret;
+}
+
+static int hte_bind_ts_info_locked(struct hte_ts_info *ei,
+				   struct hte_ts_desc *desc, u32 x_id)
+{
+	int ret = 0;
+
+	mutex_lock(&ei->req_mlock);
+
+	if (test_bit(HTE_TS_REQ, &ei->flags)) {
+		dev_dbg(ei->gdev->chip->dev, "id:%u is already requested\n",
+			desc->attr.line_id);
+		ret = -EUSERS;
+		goto out;
+	}
+
+	set_bit(HTE_TS_REQ, &ei->flags);
+	desc->hte_data = ei;
+	ei->xlated_id = x_id;
+
+out:
+	mutex_unlock(&ei->req_mlock);
+
+	return ret;
+}
+
+static struct hte_device *of_node_to_htedevice(struct device_node *np)
+{
+	struct hte_device *gdev;
+
+	spin_lock(&hte_lock);
+
+	list_for_each_entry(gdev, &hte_devices, list)
+		if (gdev->chip && gdev->chip->dev &&
+		    gdev->chip->dev->of_node == np) {
+			spin_unlock(&hte_lock);
+			return gdev;
+		}
+
+	spin_unlock(&hte_lock);
+
+	return ERR_PTR(-ENODEV);
+}
+
+static struct hte_device *hte_find_dev_from_linedata(struct hte_ts_desc *desc)
+{
+	struct hte_device *gdev;
+
+	spin_lock(&hte_lock);
+
+	list_for_each_entry(gdev, &hte_devices, list)
+		if (gdev->chip && gdev->chip->match_from_linedata) {
+			if (!gdev->chip->match_from_linedata(gdev->chip, desc))
+				continue;
+			spin_unlock(&hte_lock);
+			return gdev;
+		}
+
+	spin_unlock(&hte_lock);
+
+	return ERR_PTR(-ENODEV);
+}
+
+/**
+ * of_hte_req_count - Return the number of entities to timestamp.
+ *
+ * The function returns the total count of the requested entities to timestamp
+ * by parsing device tree.
+ *
+ * @dev: The HTE consumer.
+ *
+ * Returns: Positive number on success, -ENOENT if no entries,
+ * -EINVAL for other errors.
+ */
+int of_hte_req_count(struct device *dev)
+{
+	int count;
+
+	if (!dev || !dev->of_node)
+		return -EINVAL;
+
+	count = of_count_phandle_with_args(dev->of_node, "timestamps",
+					   "#timestamp-cells");
+
+	return count ? count : -ENOENT;
+}
+EXPORT_SYMBOL_GPL(of_hte_req_count);
+
+static inline struct hte_device *hte_get_dev(struct hte_ts_desc *desc)
+{
+	return hte_find_dev_from_linedata(desc);
+}
+
+static struct hte_device *hte_of_get_dev(struct device *dev,
+					 struct hte_ts_desc *desc,
+					 int index,
+					 struct of_phandle_args *args,
+					 bool *free_name)
+{
+	int ret;
+	struct device_node *np;
+	char *temp;
+
+	if (!dev->of_node)
+		return ERR_PTR(-EINVAL);
+
+	np = dev->of_node;
+
+	if (!of_find_property(np, "timestamp-names", NULL)) {
+		/* Let hte core construct it during request time */
+		desc->attr.name = NULL;
+	} else {
+		ret = of_property_read_string_index(np, "timestamp-names",
+						    index, &desc->attr.name);
+		if (ret) {
+			pr_err("can't parse \"timestamp-names\" property\n");
+			return ERR_PTR(ret);
+		}
+		*free_name = false;
+		if (desc->attr.name) {
+			temp = skip_spaces(desc->attr.name);
+			if (!*temp)
+				desc->attr.name = NULL;
+		}
+	}
+
+	ret = of_parse_phandle_with_args(np, "timestamps", "#timestamp-cells",
+					 index, args);
+	if (ret) {
+		pr_err("%s(): can't parse \"timestamps\" property\n",
+		       __func__);
+		return ERR_PTR(ret);
+	}
+
+	of_node_put(args->np);
+
+	return of_node_to_htedevice(args->np);
+}
+
+/**
+ * hte_ts_get() - The function to initialize and obtain HTE desc.
+ *
+ * The function initializes the consumer provided HTE descriptor. If consumer
+ * has device tree node, index is used to parse the line id and other details.
+ * The function needs to be called before using any request APIs.
+ *
+ * @dev: HTE consumer/client device, used in case of parsing device tree node.
+ * @desc: Pre-allocated timestamp descriptor.
+ * @index: The index will be used as an index to parse line_id from the
+ * device tree node if node is present.
+ *
+ * Context: Holds mutex lock.
+ * Returns: Returns 0 on success or negative error code on failure.
+ */
+int hte_ts_get(struct device *dev, struct hte_ts_desc *desc, int index)
+{
+	struct hte_device *gdev;
+	struct hte_ts_info *ei;
+	const struct fwnode_handle *fwnode;
+	struct of_phandle_args args;
+	u32 xlated_id;
+	int ret;
+	bool free_name = false;
+
+	if (!desc)
+		return -EINVAL;
+
+	fwnode = dev ? dev_fwnode(dev) : NULL;
+
+	if (is_of_node(fwnode))
+		gdev = hte_of_get_dev(dev, desc, index, &args, &free_name);
+	else
+		gdev = hte_get_dev(desc);
+
+	if (IS_ERR(gdev)) {
+		pr_err("%s() no hte dev found\n", __func__);
+		return PTR_ERR(gdev);
+	}
+
+	if (!try_module_get(gdev->owner))
+		return -ENODEV;
+
+	if (!gdev->chip) {
+		pr_err("%s(): requested id does not have provider\n",
+		       __func__);
+		ret = -ENODEV;
+		goto put;
+	}
+
+	if (is_of_node(fwnode)) {
+		if (!gdev->chip->xlate_of)
+			ret = -EINVAL;
+		else
+			ret = gdev->chip->xlate_of(gdev->chip, &args,
+						   desc, &xlated_id);
+	} else {
+		if (!gdev->chip->xlate_plat)
+			ret = -EINVAL;
+		else
+			ret = gdev->chip->xlate_plat(gdev->chip, desc,
+						     &xlated_id);
+	}
+
+	if (ret < 0)
+		goto put;
+
+	ei = &gdev->ei[xlated_id];
+
+	ret = hte_bind_ts_info_locked(ei, desc, xlated_id);
+	if (ret)
+		goto put;
+
+	ei->free_attr_name = free_name;
+
+	return 0;
+
+put:
+	module_put(gdev->owner);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(hte_ts_get);
+
+static void __devm_hte_release_ts(void *res)
+{
+	hte_ts_put(res);
+}
+
+/**
+ * hte_request_ts_ns() - The API to request and enable hardware timestamp in
+ * nanoseconds.
+ *
+ * The entity is provider specific for example, GPIO lines, signals, buses
+ * etc...The API allocates necessary resources and enables the timestamp.
+ *
+ * @desc: Pre-allocated and initialized timestamp descriptor.
+ * @cb: Callback to push the timestamp data to consumer.
+ * @tcb: Optional callback. If its provided, subsystem initializes
+ * workqueue. It is called when cb returns HTE_RUN_SECOND_CB.
+ * @data: Client data, used during cb and tcb callbacks.
+ *
+ * Context: Holds mutex lock.
+ * Returns: Returns 0 on success or negative error code on failure.
+ */
+int hte_request_ts_ns(struct hte_ts_desc *desc, hte_ts_cb_t cb,
+		      hte_ts_sec_cb_t tcb, void *data)
+{
+	int ret;
+	struct hte_ts_info *ei;
+
+	if (!desc || !desc->hte_data || !cb)
+		return -EINVAL;
+
+	ei = desc->hte_data;
+	if (!ei || !ei->gdev)
+		return -EINVAL;
+
+	ret = __hte_req_ts(desc, cb, tcb, data);
+	if (ret < 0) {
+		dev_err(ei->gdev->chip->dev,
+			"failed to request id: %d\n", desc->attr.line_id);
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hte_request_ts_ns);
+
+/**
+ * devm_hte_request_ts_ns() - Resource managed API to request and enable
+ * hardware timestamp in nanoseconds.
+ *
+ * The entity is provider specific for example, GPIO lines, signals, buses
+ * etc...The API allocates necessary resources and enables the timestamp. It
+ * deallocates and disables automatically when the consumer exits.
+ *
+ * @dev: HTE consumer/client device.
+ * @desc: Pre-allocated and initialized timestamp descriptor.
+ * @cb: Callback to push the timestamp data to consumer.
+ * @tcb: Optional callback. If its provided, subsystem initializes
+ * workqueue. It is called when cb returns HTE_RUN_SECOND_CB.
+ * @data: Client data, used during cb and tcb callbacks.
+ *
+ * Context: Holds mutex lock.
+ * Returns: Returns 0 on success or negative error code on failure.
+ */
+int devm_hte_request_ts_ns(struct device *dev, struct hte_ts_desc *desc,
+			   hte_ts_cb_t cb, hte_ts_sec_cb_t tcb,
+			   void *data)
+{
+	int err;
+
+	if (!dev)
+		return -EINVAL;
+
+	err = hte_request_ts_ns(desc, cb, tcb, data);
+	if (err)
+		return err;
+
+	err = devm_add_action_or_reset(dev, __devm_hte_release_ts, desc);
+	if (err)
+		return err;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devm_hte_request_ts_ns);
+
+/**
+ * hte_init_line_attr() - Initialize line attributes.
+ *
+ * Zeroes out line attributes and initializes with provided arguments.
+ * The function needs to be called before calling any consumer facing
+ * functions.
+ *
+ * @desc: Pre-allocated timestamp descriptor.
+ * @line_id: line id.
+ * @edge_flags: edge flags related to line_id.
+ * @name: name of the line.
+ * @data: line data related to line_id.
+ *
+ * Context: Any.
+ * Returns: 0 on success or negative error code for the failure.
+ */
+int hte_init_line_attr(struct hte_ts_desc *desc, u32 line_id,
+		       unsigned long edge_flags, const char *name, void *data)
+{
+	if (!desc)
+		return -EINVAL;
+
+	memset(&desc->attr, 0, sizeof(desc->attr));
+
+	desc->attr.edge_flags = edge_flags;
+	desc->attr.line_id = line_id;
+	desc->attr.line_data = data;
+	if (name) {
+		name =  kstrdup_const(name, GFP_KERNEL);
+		if (!name)
+			return -ENOMEM;
+	}
+
+	desc->attr.name = name;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hte_init_line_attr);
+
+/**
+ * hte_get_clk_src_info() - Get the clock source information for a ts
+ * descriptor.
+ *
+ * @desc: ts descriptor, same as returned from request API.
+ * @ci: The API fills this structure with the clock information data.
+ *
+ * Context: Any context.
+ * Returns: 0 on success else negative error code on failure.
+ */
+int hte_get_clk_src_info(const struct hte_ts_desc *desc,
+			 struct hte_clk_info *ci)
+{
+	struct hte_chip *chip;
+	struct hte_ts_info *ei;
+
+	if (!desc || !desc->hte_data || !ci) {
+		pr_debug("%s:%d\n", __func__, __LINE__);
+		return -EINVAL;
+	}
+
+	ei = desc->hte_data;
+	if (!ei->gdev || !ei->gdev->chip)
+		return -EINVAL;
+
+	chip = ei->gdev->chip;
+	if (!chip->ops->get_clk_src_info)
+		return -EOPNOTSUPP;
+
+	return chip->ops->get_clk_src_info(chip, ci);
+}
+EXPORT_SYMBOL_GPL(hte_get_clk_src_info);
+
+/**
+ * hte_push_ts_ns() - Push timestamp data in nanoseconds.
+ *
+ * It is used by the provider to push timestamp data.
+ *
+ * @chip: The HTE chip, used during the registration.
+ * @xlated_id: entity id understood by both subsystem and provider, this is
+ * obtained from xlate callback during request API.
+ * @data: timestamp data.
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+int hte_push_ts_ns(const struct hte_chip *chip, u32 xlated_id,
+		   struct hte_ts_data *data)
+{
+	enum hte_return ret;
+	int st = 0;
+	struct hte_ts_info *ei;
+	unsigned long flag;
+
+	if (!chip || !data || !chip->gdev)
+		return -EINVAL;
+
+	if (xlated_id >= chip->nlines)
+		return -EINVAL;
+
+	ei = &chip->gdev->ei[xlated_id];
+
+	spin_lock_irqsave(&ei->slock, flag);
+
+	/* timestamp sequence counter */
+	data->seq = ei->seq++;
+
+	if (!test_bit(HTE_TS_REGISTERED, &ei->flags) ||
+	    test_bit(HTE_TS_DISABLE, &ei->flags)) {
+		dev_dbg(chip->dev, "Unknown timestamp push\n");
+		atomic_inc(&ei->dropped_ts);
+		st = -EINVAL;
+		goto unlock;
+	}
+
+	ret = ei->cb(data, ei->cl_data);
+	if (ret == HTE_RUN_SECOND_CB && ei->tcb) {
+		queue_work(system_unbound_wq, &ei->cb_work);
+		set_bit(HTE_TS_QUEUE_WK, &ei->flags);
+	}
+
+unlock:
+	spin_unlock_irqrestore(&ei->slock, flag);
+
+	return st;
+}
+EXPORT_SYMBOL_GPL(hte_push_ts_ns);
+
+static int hte_register_chip(struct hte_chip *chip)
+{
+	struct hte_device *gdev;
+	u32 i;
+
+	if (!chip || !chip->dev || !chip->dev->of_node)
+		return -EINVAL;
+
+	if (!chip->ops || !chip->ops->request || !chip->ops->release) {
+		dev_err(chip->dev, "Driver needs to provide ops\n");
+		return -EINVAL;
+	}
+
+	gdev = kzalloc(struct_size(gdev, ei, chip->nlines), GFP_KERNEL);
+	if (!gdev)
+		return -ENOMEM;
+
+	gdev->chip = chip;
+	chip->gdev = gdev;
+	gdev->nlines = chip->nlines;
+	gdev->sdev = chip->dev;
+
+	for (i = 0; i < chip->nlines; i++) {
+		gdev->ei[i].gdev = gdev;
+		mutex_init(&gdev->ei[i].req_mlock);
+		spin_lock_init(&gdev->ei[i].slock);
+	}
+
+	if (chip->dev->driver)
+		gdev->owner = chip->dev->driver->owner;
+	else
+		gdev->owner = THIS_MODULE;
+
+	of_node_get(chip->dev->of_node);
+
+	INIT_LIST_HEAD(&gdev->list);
+
+	spin_lock(&hte_lock);
+	list_add_tail(&gdev->list, &hte_devices);
+	spin_unlock(&hte_lock);
+
+	hte_chip_dbgfs_init(gdev);
+
+	dev_dbg(chip->dev, "Added hte chip\n");
+
+	return 0;
+}
+
+static int hte_unregister_chip(struct hte_chip *chip)
+{
+	struct hte_device *gdev;
+
+	if (!chip)
+		return -EINVAL;
+
+	gdev = chip->gdev;
+
+	spin_lock(&hte_lock);
+	list_del(&gdev->list);
+	spin_unlock(&hte_lock);
+
+	gdev->chip = NULL;
+
+	of_node_put(chip->dev->of_node);
+	debugfs_remove_recursive(gdev->dbg_root);
+	kfree(gdev);
+
+	dev_dbg(chip->dev, "Removed hte chip\n");
+
+	return 0;
+}
+
+static void _hte_devm_unregister_chip(void *chip)
+{
+	hte_unregister_chip(chip);
+}
+
+/**
+ * devm_hte_register_chip() - Resource managed API to register HTE chip.
+ *
+ * It is used by the provider to register itself with the HTE subsystem.
+ * The unregistration is done automatically when the provider exits.
+ *
+ * @chip: the HTE chip to add to subsystem.
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+int devm_hte_register_chip(struct hte_chip *chip)
+{
+	int err;
+
+	err = hte_register_chip(chip);
+	if (err)
+		return err;
+
+	err = devm_add_action_or_reset(chip->dev, _hte_devm_unregister_chip,
+				       chip);
+	if (err)
+		return err;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devm_hte_register_chip);

include/linux/gpio/consumer.h

@@ -109,6 +109,8 @@ int gpiod_get_direction(struct gpio_desc *desc);
 int gpiod_direction_input(struct gpio_desc *desc);
 int gpiod_direction_output(struct gpio_desc *desc, int value);
 int gpiod_direction_output_raw(struct gpio_desc *desc, int value);
+int gpiod_enable_hw_timestamp_ns(struct gpio_desc *desc, unsigned long flags);
+int gpiod_disable_hw_timestamp_ns(struct gpio_desc *desc, unsigned long flags);
 
 /* Value get/set from non-sleeping context */
 int gpiod_get_value(const struct gpio_desc *desc);
@@ -350,8 +352,18 @@ static inline int gpiod_direction_output_raw(struct gpio_desc *desc, int value)
 	WARN_ON(desc);
 	return -ENOSYS;
 }
-
-
+static inline int gpiod_enable_hw_timestamp_ns(struct gpio_desc *desc,
+					       unsigned long flags)
+{
+	WARN_ON(desc);
+	return -ENOSYS;
+}
+static inline int gpiod_disable_hw_timestamp_ns(struct gpio_desc *desc,
+						unsigned long flags)
+{
+	WARN_ON(desc);
+	return -ENOSYS;
+}
 static inline int gpiod_get_value(const struct gpio_desc *desc)
 {
 	/* GPIO can never have been requested */

include/linux/gpio/driver.h

@@ -333,6 +333,10 @@ struct gpio_irq_chip {
  * @add_pin_ranges: optional routine to initialize pin ranges, to be used when
  *	requires special mapping of the pins that provides GPIO functionality.
  *	It is called after adding GPIO chip and before adding IRQ chip.
+ * @en_hw_timestamp: Dependent on GPIO chip, an optional routine to
+ *	enable hardware timestamp.
+ * @dis_hw_timestamp: Dependent on GPIO chip, an optional routine to
+ *	disable hardware timestamp.
  * @base: identifies the first GPIO number handled by this chip;
  *	or, if negative during registration, requests dynamic ID allocation.
  *	DEPRECATION: providing anything non-negative and nailing the base
@@ -429,6 +433,12 @@ struct gpio_chip {
 
 	int			(*add_pin_ranges)(struct gpio_chip *gc);
 
+	int			(*en_hw_timestamp)(struct gpio_chip *gc,
+						   u32 offset,
+						   unsigned long flags);
+	int			(*dis_hw_timestamp)(struct gpio_chip *gc,
+						    u32 offset,
+						    unsigned long flags);
 	int			base;
 	u16			ngpio;
 	u16			offset;

include/linux/hte.h

+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __LINUX_HTE_H
+#define __LINUX_HTE_H
+
+#include <linux/errno.h>
+
+struct hte_chip;
+struct hte_device;
+struct of_phandle_args;
+
+/**
+ * enum hte_edge - HTE line edge flags.
+ *
+ * @HTE_EDGE_NO_SETUP: No edge setup. In this case consumer will setup edges,
+ * for example during request irq call.
+ * @HTE_RISING_EDGE_TS: Rising edge.
+ * @HTE_FALLING_EDGE_TS: Falling edge.
+ *
+ */
+enum hte_edge {
+	HTE_EDGE_NO_SETUP = 1U << 0,
+	HTE_RISING_EDGE_TS = 1U << 1,
+	HTE_FALLING_EDGE_TS = 1U << 2,
+};
+
+/**
+ * enum hte_return - HTE subsystem return values used during callback.
+ *
+ * @HTE_CB_HANDLED: The consumer handled the data.
+ * @HTE_RUN_SECOND_CB: The consumer needs further processing, in that case
+ * HTE subsystem calls secondary callback provided by the consumer where it
+ * is allowed to sleep.
+ */
+enum hte_return {
+	HTE_CB_HANDLED,
+	HTE_RUN_SECOND_CB,
+};
+
+/**
+ * struct hte_ts_data - HTE timestamp data.
+ *
+ * @tsc: Timestamp value.
+ * @seq: Sequence counter of the timestamps.
+ * @raw_level: Level of the line at the timestamp if provider supports it,
+ * -1 otherwise.
+ */
+struct hte_ts_data {
+	u64 tsc;
+	u64 seq;
+	int raw_level;
+};
+
+/**
+ * struct hte_clk_info - Clock source info that HTE provider uses to timestamp.
+ *
+ * @hz: Supported clock rate in HZ, for example 1KHz clock = 1000.
+ * @type: Supported clock type.
+ */
+struct hte_clk_info {
+	u64 hz;
+	clockid_t type;
+};
+
+/**
+ * typedef hte_ts_cb_t - HTE timestamp data processing primary callback.
+ *
+ * The callback is used to push timestamp data to the client and it is
+ * not allowed to sleep.
+ *
+ * @ts: HW timestamp data.
+ * @data: Client supplied data.
+ */
+typedef enum hte_return (*hte_ts_cb_t)(struct hte_ts_data *ts, void *data);
+
+/**
+ * typedef hte_ts_sec_cb_t - HTE timestamp data processing secondary callback.
+ *
+ * This is used when the client needs further processing where it is
+ * allowed to sleep.
+ *
+ * @data: Client supplied data.
+ *
+ */
+typedef enum hte_return (*hte_ts_sec_cb_t)(void *data);
+
+/**
+ * struct hte_line_attr - Line attributes.
+ *
+ * @line_id: The logical ID understood by the consumers and providers.
+ * @line_data: Line data related to line_id.
+ * @edge_flags: Edge setup flags.
+ * @name: Descriptive name of the entity that is being monitored for the
+ * hardware timestamping. If null, HTE core will construct the name.
+ *
+ */
+struct hte_line_attr {
+	u32 line_id;
+	void *line_data;
+	unsigned long edge_flags;
+	const char *name;
+};
+
+/**
+ * struct hte_ts_desc - HTE timestamp descriptor.
+ *
+ * This structure is a communication token between consumers to subsystem
+ * and subsystem to providers.
+ *
+ * @attr: The line attributes.
+ * @hte_data: Subsystem's private data, set by HTE subsystem.
+ */
+struct hte_ts_desc {
+	struct hte_line_attr attr;
+	void *hte_data;
+};
+
+/**
+ * struct hte_ops - HTE operations set by providers.
+ *
+ * @request: Hook for requesting a HTE timestamp. Returns 0 on success,
+ * non-zero for failures.
+ * @release: Hook for releasing a HTE timestamp. Returns 0 on success,
+ * non-zero for failures.
+ * @enable: Hook to enable the specified timestamp. Returns 0 on success,
+ * non-zero for failures.
+ * @disable: Hook to disable specified timestamp. Returns 0 on success,
+ * non-zero for failures.
+ * @get_clk_src_info: Hook to get the clock information the provider uses
+ * to timestamp. Returns 0 for success and negative error code for failure. On
+ * success HTE subsystem fills up provided struct hte_clk_info.
+ *
+ * xlated_id parameter is used to communicate between HTE subsystem and the
+ * providers and is translated by the provider.
+ */
+struct hte_ops {
+	int (*request)(struct hte_chip *chip, struct hte_ts_desc *desc,
+		       u32 xlated_id);
+	int (*release)(struct hte_chip *chip, struct hte_ts_desc *desc,
+		       u32 xlated_id);
+	int (*enable)(struct hte_chip *chip, u32 xlated_id);
+	int (*disable)(struct hte_chip *chip, u32 xlated_id);
+	int (*get_clk_src_info)(struct hte_chip *chip,
+				struct hte_clk_info *ci);
+};
+
+/**
+ * struct hte_chip - Abstract HTE chip.
+ *
+ * @name: functional name of the HTE IP block.
+ * @dev: device providing the HTE.
+ * @ops: callbacks for this HTE.
+ * @nlines: number of lines/signals supported by this chip.
+ * @xlate_of: Callback which translates consumer supplied logical ids to
+ * physical ids, return 0 for the success and negative for the failures.
+ * It stores (between 0 to @nlines) in xlated_id parameter for the success.
+ * @xlate_plat: Same as above but for the consumers with no DT node.
+ * @match_from_linedata: Match HTE device using the line_data.
+ * @of_hte_n_cells: Number of cells used to form the HTE specifier.
+ * @gdev: HTE subsystem abstract device, internal to the HTE subsystem.
+ * @data: chip specific private data.
+ */
+struct hte_chip {
+	const char *name;
+	struct device *dev;
+	const struct hte_ops *ops;
+	u32 nlines;
+	int (*xlate_of)(struct hte_chip *gc,
+			const struct of_phandle_args *args,
+			struct hte_ts_desc *desc, u32 *xlated_id);
+	int (*xlate_plat)(struct hte_chip *gc, struct hte_ts_desc *desc,
+			 u32 *xlated_id);
+	bool (*match_from_linedata)(const struct hte_chip *chip,
+				    const struct hte_ts_desc *hdesc);
+	u8 of_hte_n_cells;
+
+	struct hte_device *gdev;
+	void *data;
+};
+
+#if IS_ENABLED(CONFIG_HTE)
+/* HTE APIs for the providers */
+int devm_hte_register_chip(struct hte_chip *chip);
+int hte_push_ts_ns(const struct hte_chip *chip, u32 xlated_id,
+		   struct hte_ts_data *data);
+
+/* HTE APIs for the consumers */
+int hte_init_line_attr(struct hte_ts_desc *desc, u32 line_id,
+		       unsigned long edge_flags, const char *name,
+		       void *data);
+int hte_ts_get(struct device *dev, struct hte_ts_desc *desc, int index);
+int hte_ts_put(struct hte_ts_desc *desc);
+int hte_request_ts_ns(struct hte_ts_desc *desc, hte_ts_cb_t cb,
+		      hte_ts_sec_cb_t tcb, void *data);
+int devm_hte_request_ts_ns(struct device *dev, struct hte_ts_desc *desc,
+			   hte_ts_cb_t cb, hte_ts_sec_cb_t tcb, void *data);
+int of_hte_req_count(struct device *dev);
+int hte_enable_ts(struct hte_ts_desc *desc);
+int hte_disable_ts(struct hte_ts_desc *desc);
+int hte_get_clk_src_info(const struct hte_ts_desc *desc,
+			 struct hte_clk_info *ci);
+
+#else /* !CONFIG_HTE */
+static inline int devm_hte_register_chip(struct hte_chip *chip)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int hte_push_ts_ns(const struct hte_chip *chip,
+				 u32 xlated_id,
+				 const struct hte_ts_data *data)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int hte_init_line_attr(struct hte_ts_desc *desc, u32 line_id,
+				     unsigned long edge_flags,
+				     const char *name, void *data)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int hte_ts_get(struct device *dev, struct hte_ts_desc *desc,
+			     int index)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int hte_ts_put(struct hte_ts_desc *desc)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int hte_request_ts_ns(struct hte_ts_desc *desc, hte_ts_cb_t cb,
+				    hte_ts_sec_cb_t tcb, void *data)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int devm_hte_request_ts_ns(struct device *dev,
+					 struct hte_ts_desc *desc,
+					 hte_ts_cb_t cb,
+					 hte_ts_sec_cb_t tcb,
+					 void *data)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int of_hte_req_count(struct device *dev)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int hte_enable_ts(struct hte_ts_desc *desc)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int hte_disable_ts(struct hte_ts_desc *desc)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int hte_get_clk_src_info(const struct hte_ts_desc *desc,
+				       struct hte_clk_info *ci)
+{
+	return -EOPNOTSUPP;
+}
+#endif /* !CONFIG_HTE */
+
+#endif

include/uapi/linux/gpio.h

@@ -66,6 +66,8 @@ struct gpiochip_info {
  * @GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN: line has pull-down bias enabled
  * @GPIO_V2_LINE_FLAG_BIAS_DISABLED: line has bias disabled
  * @GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME: line events contain REALTIME timestamps
+ * @GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE: line events contain timestamps from
+ * hardware timestamp engine
  */
 enum gpio_v2_line_flag {
 	GPIO_V2_LINE_FLAG_USED			= _BITULL(0),
@@ -80,6 +82,7 @@ enum gpio_v2_line_flag {
 	GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN	= _BITULL(9),
 	GPIO_V2_LINE_FLAG_BIAS_DISABLED		= _BITULL(10),
 	GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME	= _BITULL(11),
+	GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE	= _BITULL(12),
 };
 
 /**

tools/gpio/gpio-event-mon.c

@@ -149,6 +149,7 @@ void print_usage(void)
 		"  -r         Listen for rising edges\n"
 		"  -f         Listen for falling edges\n"
 		"  -w         Report the wall-clock time for events\n"
+		"  -t         Report the hardware timestamp for events\n"
 		"  -b <n>     Debounce the line with period n microseconds\n"
 		" [-c <n>]    Do <n> loops (optional, infinite loop if not stated)\n"
 		"  -?         This helptext\n"
@@ -174,7 +175,7 @@ int main(int argc, char **argv)
 
 	memset(&config, 0, sizeof(config));
 	config.flags = GPIO_V2_LINE_FLAG_INPUT;
-	while ((c = getopt(argc, argv, "c:n:o:b:dsrfw?")) != -1) {
+	while ((c = getopt(argc, argv, "c:n:o:b:dsrfwt?")) != -1) {
 		switch (c) {
 		case 'c':
 			loops = strtoul(optarg, NULL, 10);
@@ -208,6 +209,9 @@ int main(int argc, char **argv)
 		case 'w':
 			config.flags |= GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME;
 			break;
+		case 't':
+			config.flags |= GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE;
+			break;
 		case '?':
 			print_usage();
 			return -1;