1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (c) 2021-2022 NVIDIA Corporation
  4 *
  5 * Author: Dipen Patel <dipenp@nvidia.com>
  6 */
  7
  8#include <linux/err.h>
  9#include <linux/gpio/consumer.h>
 10#include <linux/hte.h>
 11#include <linux/interrupt.h>
 12#include <linux/mod_devicetable.h>
 13#include <linux/module.h>
 14#include <linux/platform_device.h>
 15#include <linux/timer.h>
 16#include <linux/workqueue.h>
 17
 18/*
 19 * This sample HTE test driver demonstrates HTE API usage by enabling
 20 * hardware timestamp on gpio_in and specified LIC IRQ lines.
 21 *
 22 * Note: gpio_out and gpio_in need to be shorted externally in order for this
 23 * test driver to work for the GPIO monitoring. The test driver has been
 24 * tested on Jetson AGX Xavier platform by shorting pin 32 and 16 on 40 pin
 25 * header.
 26 *
 27 * Device tree snippet to activate this driver:
 28 *	tegra_hte_test {
 29 *		compatible = "nvidia,tegra194-hte-test";
 30 *		in-gpio = <&gpio_aon TEGRA194_AON_GPIO(BB, 1)>;
 31 *		out-gpio = <&gpio_aon TEGRA194_AON_GPIO(BB, 0)>;
 32 *		timestamps = <&tegra_hte_aon TEGRA194_AON_GPIO(BB, 1)>,
 33 *			     <&tegra_hte_lic 0x19>;
 34 *		timestamp-names = "hte-gpio", "hte-i2c-irq";
 35 *		status = "okay";
 36 *	};
 37 *
 38 * How to run test driver:
 39 * - Load test driver.
 40 * - For the GPIO, at regular interval gpio_out pin toggles triggering
 41 *   HTE for rising edge on gpio_in pin.
 42 *
 43 * - For the LIC IRQ line, it uses 0x19 interrupt which is i2c controller 1.
 44 * - Run i2cdetect -y 1 1>/dev/null, this command will generate i2c bus
 45 *   transactions which creates timestamp data.
 46 * - It prints below message for both the lines.
 47 *   HW timestamp(<line id>:<ts seq number>): <timestamp>, edge: <edge>.
 48 * - Unloading the driver disables and deallocate the HTE.
 49 */
 50
 51static struct tegra_hte_test {
 52	int gpio_in_irq;
 53	struct device *pdev;
 54	struct gpio_desc *gpio_in;
 55	struct gpio_desc *gpio_out;
 56	struct hte_ts_desc *desc;
 57	struct timer_list timer;
 58	struct kobject *kobj;
 59} hte;
 60
 61static enum hte_return process_hw_ts(struct hte_ts_data *ts, void *p)
 62{
 63	char *edge;
 64	struct hte_ts_desc *desc = p;
 65
 66	if (!ts || !p)
 67		return HTE_CB_HANDLED;
 68
 69	if (ts->raw_level < 0)
 70		edge = "Unknown";
 71
 72	pr_info("HW timestamp(%u: %llu): %llu, edge: %s\n",
 73		desc->attr.line_id, ts->seq, ts->tsc,
 74		(ts->raw_level >= 0) ? ((ts->raw_level == 0) ?
 75					"falling" : "rising") : edge);
 76
 77	return HTE_CB_HANDLED;
 78}
 79
 80static void gpio_timer_cb(struct timer_list *t)
 81{
 82	(void)t;
 83
 84	gpiod_set_value(hte.gpio_out, !gpiod_get_value(hte.gpio_out));
 85	mod_timer(&hte.timer, jiffies + msecs_to_jiffies(8000));
 86}
 87
 88static irqreturn_t tegra_hte_test_gpio_isr(int irq, void *data)
 89{
 90	(void)irq;
 91	(void)data;
 92
 93	return IRQ_HANDLED;
 94}
 95
 96static const struct of_device_id tegra_hte_test_of_match[] = {
 97	{ .compatible = "nvidia,tegra194-hte-test"},
 98	{ }
 99};
100MODULE_DEVICE_TABLE(of, tegra_hte_test_of_match);
101
102static int tegra_hte_test_probe(struct platform_device *pdev)
103{
104	int ret = 0;
105	int i, cnt;
106
107	dev_set_drvdata(&pdev->dev, &hte);
108	hte.pdev = &pdev->dev;
109
110	hte.gpio_out = gpiod_get(&pdev->dev, "out", 0);
111	if (IS_ERR(hte.gpio_out)) {
112		dev_err(&pdev->dev, "failed to get gpio out\n");
113		ret = -EINVAL;
114		goto out;
115	}
116
117	hte.gpio_in = gpiod_get(&pdev->dev, "in", 0);
118	if (IS_ERR(hte.gpio_in)) {
119		dev_err(&pdev->dev, "failed to get gpio in\n");
120		ret = -EINVAL;
121		goto free_gpio_out;
122	}
123
124	ret = gpiod_direction_output(hte.gpio_out, 0);
125	if (ret) {
126		dev_err(&pdev->dev, "failed to set output\n");
127		ret = -EINVAL;
128		goto free_gpio_in;
129	}
130
131	ret = gpiod_direction_input(hte.gpio_in);
132	if (ret) {
133		dev_err(&pdev->dev, "failed to set input\n");
134		ret = -EINVAL;
135		goto free_gpio_in;
136	}
137
138	ret = gpiod_to_irq(hte.gpio_in);
139	if (ret < 0) {
140		dev_err(&pdev->dev, "failed to map GPIO to IRQ: %d\n", ret);
141		ret = -ENXIO;
142		goto free_gpio_in;
143	}
144
145	hte.gpio_in_irq = ret;
146	ret = request_irq(ret, tegra_hte_test_gpio_isr,
147			  IRQF_TRIGGER_RISING,
148			  "tegra_hte_gpio_test_isr", &hte);
149	if (ret) {
150		dev_err(&pdev->dev, "failed to acquire IRQ\n");
151		ret = -ENXIO;
152		goto free_irq;
153	}
154
155	cnt = of_hte_req_count(hte.pdev);
156	if (cnt < 0) {
157		ret = cnt;
158		goto free_irq;
159	}
160
161	dev_info(&pdev->dev, "Total requested lines:%d\n", cnt);
162
163	hte.desc = devm_kzalloc(hte.pdev, sizeof(*hte.desc) * cnt, GFP_KERNEL);
164	if (!hte.desc) {
165		ret = -ENOMEM;
166		goto free_irq;
167	}
168
169	for (i = 0; i < cnt; i++) {
170		if (i == 0)
171			/*
172			 * GPIO hte init, line_id and name will be parsed from
173			 * the device tree node. The edge_flag is implicitly
174			 * set by request_irq call. Only line_data is needed to be
175			 * set.
176			 */
177			hte_init_line_attr(&hte.desc[i], 0, 0, NULL,
178					   hte.gpio_in);
179		else
180			/*
181			 * same comment as above except that IRQ does not need
182			 * line data.
183			 */
184			hte_init_line_attr(&hte.desc[i], 0, 0, NULL, NULL);
185
186		ret = hte_ts_get(hte.pdev, &hte.desc[i], i);
187		if (ret)
188			goto ts_put;
189
190		ret = devm_hte_request_ts_ns(hte.pdev, &hte.desc[i],
191					     process_hw_ts, NULL,
192					     &hte.desc[i]);
193		if (ret) /* no need to ts_put, request API takes care */
194			goto free_irq;
195	}
196
197	timer_setup(&hte.timer, gpio_timer_cb, 0);
198	mod_timer(&hte.timer, jiffies + msecs_to_jiffies(5000));
199
200	return 0;
201
202ts_put:
203	cnt = i;
204	for (i = 0; i < cnt; i++)
205		hte_ts_put(&hte.desc[i]);
206free_irq:
207	free_irq(hte.gpio_in_irq, &hte);
208free_gpio_in:
209	gpiod_put(hte.gpio_in);
210free_gpio_out:
211	gpiod_put(hte.gpio_out);
212out:
213
214	return ret;
215}
216
217static void tegra_hte_test_remove(struct platform_device *pdev)
218{
219	(void)pdev;
220
221	free_irq(hte.gpio_in_irq, &hte);
222	gpiod_put(hte.gpio_in);
223	gpiod_put(hte.gpio_out);
224	del_timer_sync(&hte.timer);
225}
226
227static struct platform_driver tegra_hte_test_driver = {
228	.probe = tegra_hte_test_probe,
229	.remove = tegra_hte_test_remove,
230	.driver = {
231		.name = "tegra_hte_test",
232		.of_match_table = tegra_hte_test_of_match,
233	},
234};
235module_platform_driver(tegra_hte_test_driver);
236
237MODULE_AUTHOR("Dipen Patel <dipenp@nvidia.com>");
238MODULE_DESCRIPTION("NVIDIA Tegra HTE (Hardware Timestamping Engine) test driver");
239MODULE_LICENSE("GPL");