1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * pps-gpio.c -- PPS client driver using GPIO
4 *
5 * Copyright (C) 2010 Ricardo Martins <rasm@fe.up.pt>
6 * Copyright (C) 2011 James Nuss <jamesnuss@nanometrics.ca>
7 */
8
9 #define PPS_GPIO_NAME "pps-gpio"
10 #define pr_fmt(fmt) PPS_GPIO_NAME ": " fmt
11
12 #include <linux/init.h>
13 #include <linux/kernel.h>
14 #include <linux/interrupt.h>
15 #include <linux/mod_devicetable.h>
16 #include <linux/module.h>
17 #include <linux/platform_device.h>
18 #include <linux/slab.h>
19 #include <linux/pps_kernel.h>
20 #include <linux/gpio/consumer.h>
21 #include <linux/list.h>
22 #include <linux/property.h>
23 #include <linux/timer.h>
24 #include <linux/jiffies.h>
25
26 /* Info for each registered platform device */
27 struct pps_gpio_device_data {
28 int irq; /* IRQ used as PPS source */
29 struct pps_device *pps; /* PPS source device */
30 struct pps_source_info info; /* PPS source information */
31 struct gpio_desc *gpio_pin; /* GPIO port descriptors */
32 struct gpio_desc *echo_pin;
33 struct timer_list echo_timer; /* timer to reset echo active state */
34 bool assert_falling_edge;
35 bool capture_clear;
36 unsigned int echo_active_ms; /* PPS echo active duration */
37 unsigned long echo_timeout; /* timer timeout value in jiffies */
38 };
39
40 /*
41 * Report the PPS event
42 */
43
pps_gpio_irq_handler(int irq,void * data)44 static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
45 {
46 const struct pps_gpio_device_data *info;
47 struct pps_event_time ts;
48 int rising_edge;
49
50 /* Get the time stamp first */
51 pps_get_ts(&ts);
52
53 info = data;
54
55 rising_edge = gpiod_get_value(info->gpio_pin);
56 if ((rising_edge && !info->assert_falling_edge) ||
57 (!rising_edge && info->assert_falling_edge))
58 pps_event(info->pps, &ts, PPS_CAPTUREASSERT, data);
59 else if (info->capture_clear &&
60 ((rising_edge && info->assert_falling_edge) ||
61 (!rising_edge && !info->assert_falling_edge)))
62 pps_event(info->pps, &ts, PPS_CAPTURECLEAR, data);
63
64 return IRQ_HANDLED;
65 }
66
67 /* This function will only be called when an ECHO GPIO is defined */
pps_gpio_echo(struct pps_device * pps,int event,void * data)68 static void pps_gpio_echo(struct pps_device *pps, int event, void *data)
69 {
70 /* add_timer() needs to write into info->echo_timer */
71 struct pps_gpio_device_data *info = data;
72
73 switch (event) {
74 case PPS_CAPTUREASSERT:
75 if (pps->params.mode & PPS_ECHOASSERT)
76 gpiod_set_value(info->echo_pin, 1);
77 break;
78
79 case PPS_CAPTURECLEAR:
80 if (pps->params.mode & PPS_ECHOCLEAR)
81 gpiod_set_value(info->echo_pin, 1);
82 break;
83 }
84
85 /* fire the timer */
86 if (info->pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) {
87 info->echo_timer.expires = jiffies + info->echo_timeout;
88 add_timer(&info->echo_timer);
89 }
90 }
91
92 /* Timer callback to reset the echo pin to the inactive state */
pps_gpio_echo_timer_callback(struct timer_list * t)93 static void pps_gpio_echo_timer_callback(struct timer_list *t)
94 {
95 const struct pps_gpio_device_data *info;
96
97 info = from_timer(info, t, echo_timer);
98
99 gpiod_set_value(info->echo_pin, 0);
100 }
101
pps_gpio_setup(struct device * dev)102 static int pps_gpio_setup(struct device *dev)
103 {
104 struct pps_gpio_device_data *data = dev_get_drvdata(dev);
105 int ret;
106 u32 value;
107
108 data->gpio_pin = devm_gpiod_get(dev, NULL, GPIOD_IN);
109 if (IS_ERR(data->gpio_pin))
110 return dev_err_probe(dev, PTR_ERR(data->gpio_pin),
111 "failed to request PPS GPIO\n");
112
113 data->assert_falling_edge =
114 device_property_read_bool(dev, "assert-falling-edge");
115
116 data->echo_pin = devm_gpiod_get_optional(dev, "echo", GPIOD_OUT_LOW);
117 if (IS_ERR(data->echo_pin))
118 return dev_err_probe(dev, PTR_ERR(data->echo_pin),
119 "failed to request ECHO GPIO\n");
120
121 if (!data->echo_pin)
122 return 0;
123
124 ret = device_property_read_u32(dev, "echo-active-ms", &value);
125 if (ret) {
126 dev_err(dev, "failed to get echo-active-ms from FW\n");
127 return ret;
128 }
129
130 /* sanity check on echo_active_ms */
131 if (!value || value > 999) {
132 dev_err(dev, "echo-active-ms: %u - bad value from FW\n", value);
133 return -EINVAL;
134 }
135
136 data->echo_active_ms = value;
137
138 return 0;
139 }
140
141 static unsigned long
get_irqf_trigger_flags(const struct pps_gpio_device_data * data)142 get_irqf_trigger_flags(const struct pps_gpio_device_data *data)
143 {
144 unsigned long flags = data->assert_falling_edge ?
145 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
146
147 if (data->capture_clear) {
148 flags |= ((flags & IRQF_TRIGGER_RISING) ?
149 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING);
150 }
151
152 return flags;
153 }
154
pps_gpio_probe(struct platform_device * pdev)155 static int pps_gpio_probe(struct platform_device *pdev)
156 {
157 struct pps_gpio_device_data *data;
158 struct device *dev = &pdev->dev;
159 int ret;
160 int pps_default_params;
161
162 /* allocate space for device info */
163 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
164 if (!data)
165 return -ENOMEM;
166
167 dev_set_drvdata(dev, data);
168
169 /* GPIO setup */
170 ret = pps_gpio_setup(dev);
171 if (ret)
172 return ret;
173
174 /* IRQ setup */
175 ret = gpiod_to_irq(data->gpio_pin);
176 if (ret < 0) {
177 dev_err(dev, "failed to map GPIO to IRQ: %d\n", ret);
178 return -EINVAL;
179 }
180 data->irq = ret;
181
182 /* initialize PPS specific parts of the bookkeeping data structure. */
183 data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT |
184 PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC;
185 if (data->capture_clear)
186 data->info.mode |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR |
187 PPS_ECHOCLEAR;
188 data->info.owner = THIS_MODULE;
189 snprintf(data->info.name, PPS_MAX_NAME_LEN - 1, "%s.%d",
190 pdev->name, pdev->id);
191 if (data->echo_pin) {
192 data->info.echo = pps_gpio_echo;
193 data->echo_timeout = msecs_to_jiffies(data->echo_active_ms);
194 timer_setup(&data->echo_timer, pps_gpio_echo_timer_callback, 0);
195 }
196
197 /* register PPS source */
198 pps_default_params = PPS_CAPTUREASSERT | PPS_OFFSETASSERT;
199 if (data->capture_clear)
200 pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR;
201 data->pps = pps_register_source(&data->info, pps_default_params);
202 if (IS_ERR(data->pps)) {
203 dev_err(dev, "failed to register IRQ %d as PPS source\n",
204 data->irq);
205 return PTR_ERR(data->pps);
206 }
207
208 /* register IRQ interrupt handler */
209 ret = devm_request_irq(dev, data->irq, pps_gpio_irq_handler,
210 get_irqf_trigger_flags(data), data->info.name, data);
211 if (ret) {
212 pps_unregister_source(data->pps);
213 dev_err(dev, "failed to acquire IRQ %d\n", data->irq);
214 return -EINVAL;
215 }
216
217 dev_info(data->pps->dev, "Registered IRQ %d as PPS source\n",
218 data->irq);
219
220 return 0;
221 }
222
pps_gpio_remove(struct platform_device * pdev)223 static void pps_gpio_remove(struct platform_device *pdev)
224 {
225 struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
226
227 pps_unregister_source(data->pps);
228 del_timer_sync(&data->echo_timer);
229 /* reset echo pin in any case */
230 gpiod_set_value(data->echo_pin, 0);
231 dev_info(&pdev->dev, "removed IRQ %d as PPS source\n", data->irq);
232 }
233
234 static const struct of_device_id pps_gpio_dt_ids[] = {
235 { .compatible = "pps-gpio", },
236 { /* sentinel */ }
237 };
238 MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids);
239
240 static struct platform_driver pps_gpio_driver = {
241 .probe = pps_gpio_probe,
242 .remove = pps_gpio_remove,
243 .driver = {
244 .name = PPS_GPIO_NAME,
245 .of_match_table = pps_gpio_dt_ids,
246 },
247 };
248
249 module_platform_driver(pps_gpio_driver);
250 MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
251 MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
252 MODULE_DESCRIPTION("Use GPIO pin as PPS source");
253 MODULE_LICENSE("GPL");
254 MODULE_VERSION("1.2.0");
255