@@ -0,0 +1,255 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2021 NVIDIA Corporation
+ *
+ * Author: Dipen Patel <dipenp@nvidia.com>
+ */
+
+#include <linux/version.h>
+#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>
+
+/*
+ * Tegra194 On chip HTE (hardware timestamping engine) also known as GTE
+ * (generic timestamping engine) can monitor subset of GPIO lines for the event
+ * and timestamp accordingly.
+ *
+ * This sample HTE GPIO test driver demonstrates HTE API usage indirectly
+ * through GPIOLIB framework. It enables hardware timestamp on gpio_in line.
+ *
+ * Note: gpio_out and gpio_in need to be shorted externally in order for this
+ * test driver to work for the GPIO monitoring. This test driver has been
+ * tested on Jetson AGX platform by shorting pin 32 and 16 on 40 pin header.
+ */
+
+static unsigned int gpio_in = 322;
+module_param(gpio_in, uint, 0660);
+
+static unsigned int gpio_out = 321;
+module_param(gpio_out, uint, 0660);
+
+static struct tegra_hte_test {
+ bool is_ts_en;
+ int gpio_in_irq;
+ struct gpio_desc *gpio_in;
+ struct gpio_desc *gpio_out;
+ struct timer_list timer;
+ struct work_struct ev_work;
+ struct kobject *kobj;
+} hte;
+
+static void hte_print_ts(struct work_struct *data)
+{
+ (void) data;
+ /*
+ * We are called from workqueue, it is ok to block in case ts is not
+ * yet available.
+ */
+ pr_info("GPIO HW Timestamp: %llu\n",
+ gpiod_get_hw_timestamp(hte.gpio_in, true));
+}
+
+/*
+ * Sysfs attribute to request/release HTE gpio line
+ */
+static ssize_t store_gpio_en_dis(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ int ret = count;
+ unsigned long val = 0;
+
+ if (kstrtoul(buf, 10, &val) < 0) {
+ ret = -EINVAL;
+ goto error;
+ }
+
+ if (val == 1) {
+ if (hte.is_ts_en) {
+ ret = -EEXIST;
+ goto error;
+ }
+
+ ret = gpiod_hw_timestamp_control(hte.gpio_in, true);
+ if (ret)
+ goto error;
+
+ hte.is_ts_en = true;
+ } else if (val == 0) {
+ if (!hte.is_ts_en) {
+ ret = -EINVAL;
+ goto error;
+ }
+ ret = gpiod_hw_timestamp_control(hte.gpio_in, false);
+ if (ret)
+ goto error;
+
+ hte.is_ts_en = false;
+ }
+
+ ret = count;
+
+error:
+ return ret;
+}
+
+struct kobj_attribute gpio_en_dis_attr =
+ __ATTR(gpio_en_dis, 0220, NULL, store_gpio_en_dis);
+
+static struct attribute *attrs[] = {
+ &gpio_en_dis_attr.attr,
+ NULL,
+};
+
+static struct attribute_group tegra_hte_test_attr_group = {
+ .attrs = attrs,
+};
+
+static int tegra_hte_test_sysfs_create(void)
+{
+ int ret;
+
+ /* Creates /sys/kernel/tegra_hte_gpio_test */
+ hte.kobj = kobject_create_and_add("tegra_hte_gpio_test", kernel_kobj);
+ if (!hte.kobj)
+ return -ENOMEM;
+
+ ret = sysfs_create_group(hte.kobj, &tegra_hte_test_attr_group);
+ if (ret)
+ kobject_put(hte.kobj);
+ return ret;
+}
+
+static void gpio_timer_cb(struct timer_list *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)
+{
+ struct tegra_hte_test *hte = data;
+ u64 ts;
+
+ ts = gpiod_get_hw_timestamp(hte->gpio_in, false);
+ if (!ts)
+ schedule_work(&hte->ev_work);
+ else
+ pr_info("GPIO HW timestamp(ISR): %llu", ts);
+
+ return IRQ_HANDLED;
+}
+
+static int __init tegra_hte_gpio_test_init(void)
+{
+ int ret = 0;
+
+ ret = gpio_request(gpio_out, "gte_test_gpio_out");
+ if (ret) {
+ pr_err("failed request gpio out\n");
+ return -EINVAL;
+ }
+
+ ret = gpio_request(gpio_in, "gte_test_gpio_in");
+ if (ret) {
+ pr_err("failed request gpio in\n");
+ ret = -EINVAL;
+ goto free_gpio_out;
+ }
+
+ hte.gpio_out = gpio_to_desc(gpio_out);
+ if (!hte.gpio_out) {
+ pr_err("failed convert gpio out to desc\n");
+ ret = -EINVAL;
+ goto free_gpio_in;
+ }
+
+ hte.gpio_in = gpio_to_desc(gpio_in);
+ if (!hte.gpio_in) {
+ pr_err("failed convert gpio in to desc\n");
+ ret = -EINVAL;
+ goto free_gpio_in;
+ }
+
+ ret = gpiod_direction_output(hte.gpio_out, 0);
+ if (ret) {
+ pr_err("failed to set output\n");
+ ret = -EINVAL;
+ goto free_gpio_in;
+ }
+
+ ret = gpiod_direction_input(hte.gpio_in);
+ if (ret) {
+ pr_err("failed to set input\n");
+ ret = -EINVAL;
+ goto free_gpio_in;
+ }
+
+ /* IRQ setup */
+ ret = gpiod_to_irq(hte.gpio_in);
+ if (ret < 0) {
+ pr_err("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) {
+ pr_err("failed to acquire IRQ\n");
+ ret = -ENXIO;
+ goto free_irq;
+ }
+
+ ret = tegra_hte_test_sysfs_create();
+ if (ret != 0) {
+ pr_err("sysfs creation failed\n");
+ ret = -ENXIO;
+ goto free_irq;
+ }
+
+ timer_setup(&hte.timer, gpio_timer_cb, 0);
+
+ INIT_WORK(&hte.ev_work, hte_print_ts);
+ mod_timer(&hte.timer, jiffies + msecs_to_jiffies(5000));
+
+ return 0;
+
+free_irq:
+ free_irq(hte.gpio_in_irq, &hte);
+free_gpio_in:
+ gpio_free(gpio_in);
+free_gpio_out:
+ gpio_free(gpio_out);
+
+ return ret;
+}
+
+static void __exit tegra_hte_gpio_test_exit(void)
+{
+ int ret;
+
+ cancel_work_sync(&hte.ev_work);
+ free_irq(hte.gpio_in_irq, &hte);
+ gpio_free(gpio_in);
+ gpio_free(gpio_out);
+ ret = gpiod_hw_timestamp_control(hte.gpio_in, false);
+ if (ret)
+ pr_err("failed to disable hw control\n");
+ kobject_put(hte.kobj);
+ del_timer(&hte.timer);
+}
+
+module_init(tegra_hte_gpio_test_init);
+module_exit(tegra_hte_gpio_test_exit);
+MODULE_AUTHOR("Dipen Patel <dipenp@nvidia.com>");
+MODULE_LICENSE("GPL v2");