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/module.h>
10 #include <linux/moduleparam.h>
11 #include <linux/interrupt.h>
12 #include <linux/gpio.h>
13 #include <linux/timer.h>
14 #include <linux/platform_device.h>
15 #include <linux/workqueue.h>
16 #include <linux/hte.h>
17 
18 /*
19  * This sample HTE GPIO 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 
51 static 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 
61 static 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 
80 static 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 
88 static 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 
96 static const struct of_device_id tegra_hte_test_of_match[] = {
97 	{ .compatible = "nvidia,tegra194-hte-test"},
98 	{ }
99 };
100 MODULE_DEVICE_TABLE(of, tegra_hte_test_of_match);
101 
102 static 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 		goto free_irq;
158 
159 	dev_info(&pdev->dev, "Total requested lines:%d\n", cnt);
160 
161 	hte.desc = devm_kzalloc(hte.pdev, sizeof(*hte.desc) * cnt, GFP_KERNEL);
162 	if (!hte.desc) {
163 		ret = -ENOMEM;
164 		goto free_irq;
165 	}
166 
167 	for (i = 0; i < cnt; i++) {
168 		if (i == 0)
169 			/*
170 			 * GPIO hte init, line_id and name will be parsed from
171 			 * the device tree node. The edge_flag is implicitly
172 			 * set by request_irq call. Only line_data is needed to be
173 			 * set.
174 			 */
175 			hte_init_line_attr(&hte.desc[i], 0, 0, NULL,
176 					   hte.gpio_in);
177 		else
178 			/*
179 			 * same comment as above except that IRQ does not need
180 			 * line data.
181 			 */
182 			hte_init_line_attr(&hte.desc[i], 0, 0, NULL, NULL);
183 
184 		ret = hte_ts_get(hte.pdev, &hte.desc[i], i);
185 		if (ret)
186 			goto ts_put;
187 
188 		ret = devm_hte_request_ts_ns(hte.pdev, &hte.desc[i],
189 					     process_hw_ts, NULL,
190 					     &hte.desc[i]);
191 		if (ret) /* no need to ts_put, request API takes care */
192 			goto free_irq;
193 	}
194 
195 	timer_setup(&hte.timer, gpio_timer_cb, 0);
196 	mod_timer(&hte.timer, jiffies + msecs_to_jiffies(5000));
197 
198 	return 0;
199 
200 ts_put:
201 	cnt = i;
202 	for (i = 0; i < cnt; i++)
203 		hte_ts_put(&hte.desc[i]);
204 free_irq:
205 	free_irq(hte.gpio_in_irq, &hte);
206 free_gpio_in:
207 	gpiod_put(hte.gpio_in);
208 free_gpio_out:
209 	gpiod_put(hte.gpio_out);
210 out:
211 
212 	return ret;
213 }
214 
215 static int tegra_hte_test_remove(struct platform_device *pdev)
216 {
217 	(void)pdev;
218 
219 	free_irq(hte.gpio_in_irq, &hte);
220 	gpiod_put(hte.gpio_in);
221 	gpiod_put(hte.gpio_out);
222 	del_timer_sync(&hte.timer);
223 
224 	return 0;
225 }
226 
227 static 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 };
235 module_platform_driver(tegra_hte_test_driver);
236 
237 MODULE_AUTHOR("Dipen Patel <dipenp@nvidia.com>");
238 MODULE_LICENSE("GPL");
239