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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 */
27struct 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
44static 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 */
68static 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 */
93static 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
102static 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
141static unsigned long
142get_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
155static 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
223static int 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 return 0;
233}
234
235static const struct of_device_id pps_gpio_dt_ids[] = {
236 { .compatible = "pps-gpio", },
237 { /* sentinel */ }
238};
239MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids);
240
241static struct platform_driver pps_gpio_driver = {
242 .probe = pps_gpio_probe,
243 .remove = pps_gpio_remove,
244 .driver = {
245 .name = PPS_GPIO_NAME,
246 .of_match_table = pps_gpio_dt_ids,
247 },
248};
249
250module_platform_driver(pps_gpio_driver);
251MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
252MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
253MODULE_DESCRIPTION("Use GPIO pin as PPS source");
254MODULE_LICENSE("GPL");
255MODULE_VERSION("1.2.0");
1/*
2 * pps-gpio.c -- PPS client driver using GPIO
3 *
4 *
5 * Copyright (C) 2010 Ricardo Martins <rasm@fe.up.pt>
6 * Copyright (C) 2011 James Nuss <jamesnuss@nanometrics.ca>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 */
22
23#define PPS_GPIO_NAME "pps-gpio"
24#define pr_fmt(fmt) PPS_GPIO_NAME ": " fmt
25
26#include <linux/init.h>
27#include <linux/kernel.h>
28#include <linux/interrupt.h>
29#include <linux/module.h>
30#include <linux/platform_device.h>
31#include <linux/slab.h>
32#include <linux/pps_kernel.h>
33#include <linux/pps-gpio.h>
34#include <linux/gpio.h>
35#include <linux/list.h>
36#include <linux/of_device.h>
37#include <linux/of_gpio.h>
38
39/* Info for each registered platform device */
40struct pps_gpio_device_data {
41 int irq; /* IRQ used as PPS source */
42 struct pps_device *pps; /* PPS source device */
43 struct pps_source_info info; /* PPS source information */
44 bool assert_falling_edge;
45 bool capture_clear;
46 unsigned int gpio_pin;
47};
48
49/*
50 * Report the PPS event
51 */
52
53static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
54{
55 const struct pps_gpio_device_data *info;
56 struct pps_event_time ts;
57 int rising_edge;
58
59 /* Get the time stamp first */
60 pps_get_ts(&ts);
61
62 info = data;
63
64 rising_edge = gpio_get_value(info->gpio_pin);
65 if ((rising_edge && !info->assert_falling_edge) ||
66 (!rising_edge && info->assert_falling_edge))
67 pps_event(info->pps, &ts, PPS_CAPTUREASSERT, NULL);
68 else if (info->capture_clear &&
69 ((rising_edge && info->assert_falling_edge) ||
70 (!rising_edge && !info->assert_falling_edge)))
71 pps_event(info->pps, &ts, PPS_CAPTURECLEAR, NULL);
72
73 return IRQ_HANDLED;
74}
75
76static unsigned long
77get_irqf_trigger_flags(const struct pps_gpio_device_data *data)
78{
79 unsigned long flags = data->assert_falling_edge ?
80 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
81
82 if (data->capture_clear) {
83 flags |= ((flags & IRQF_TRIGGER_RISING) ?
84 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING);
85 }
86
87 return flags;
88}
89
90static int pps_gpio_probe(struct platform_device *pdev)
91{
92 struct pps_gpio_device_data *data;
93 const char *gpio_label;
94 int ret;
95 int pps_default_params;
96 const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data;
97 struct device_node *np = pdev->dev.of_node;
98
99 /* allocate space for device info */
100 data = devm_kzalloc(&pdev->dev, sizeof(struct pps_gpio_device_data),
101 GFP_KERNEL);
102 if (!data)
103 return -ENOMEM;
104
105 if (pdata) {
106 data->gpio_pin = pdata->gpio_pin;
107 gpio_label = pdata->gpio_label;
108
109 data->assert_falling_edge = pdata->assert_falling_edge;
110 data->capture_clear = pdata->capture_clear;
111 } else {
112 ret = of_get_gpio(np, 0);
113 if (ret < 0) {
114 dev_err(&pdev->dev, "failed to get GPIO from device tree\n");
115 return ret;
116 }
117 data->gpio_pin = ret;
118 gpio_label = PPS_GPIO_NAME;
119
120 if (of_get_property(np, "assert-falling-edge", NULL))
121 data->assert_falling_edge = true;
122 }
123
124 /* GPIO setup */
125 ret = devm_gpio_request(&pdev->dev, data->gpio_pin, gpio_label);
126 if (ret) {
127 dev_err(&pdev->dev, "failed to request GPIO %u\n",
128 data->gpio_pin);
129 return ret;
130 }
131
132 ret = gpio_direction_input(data->gpio_pin);
133 if (ret) {
134 dev_err(&pdev->dev, "failed to set pin direction\n");
135 return -EINVAL;
136 }
137
138 /* IRQ setup */
139 ret = gpio_to_irq(data->gpio_pin);
140 if (ret < 0) {
141 dev_err(&pdev->dev, "failed to map GPIO to IRQ: %d\n", ret);
142 return -EINVAL;
143 }
144 data->irq = ret;
145
146 /* initialize PPS specific parts of the bookkeeping data structure. */
147 data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT |
148 PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC;
149 if (data->capture_clear)
150 data->info.mode |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR |
151 PPS_ECHOCLEAR;
152 data->info.owner = THIS_MODULE;
153 snprintf(data->info.name, PPS_MAX_NAME_LEN - 1, "%s.%d",
154 pdev->name, pdev->id);
155
156 /* register PPS source */
157 pps_default_params = PPS_CAPTUREASSERT | PPS_OFFSETASSERT;
158 if (data->capture_clear)
159 pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR;
160 data->pps = pps_register_source(&data->info, pps_default_params);
161 if (data->pps == NULL) {
162 dev_err(&pdev->dev, "failed to register IRQ %d as PPS source\n",
163 data->irq);
164 return -EINVAL;
165 }
166
167 /* register IRQ interrupt handler */
168 ret = devm_request_irq(&pdev->dev, data->irq, pps_gpio_irq_handler,
169 get_irqf_trigger_flags(data), data->info.name, data);
170 if (ret) {
171 pps_unregister_source(data->pps);
172 dev_err(&pdev->dev, "failed to acquire IRQ %d\n", data->irq);
173 return -EINVAL;
174 }
175
176 platform_set_drvdata(pdev, data);
177 dev_info(data->pps->dev, "Registered IRQ %d as PPS source\n",
178 data->irq);
179
180 return 0;
181}
182
183static int pps_gpio_remove(struct platform_device *pdev)
184{
185 struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
186
187 pps_unregister_source(data->pps);
188 dev_info(&pdev->dev, "removed IRQ %d as PPS source\n", data->irq);
189 return 0;
190}
191
192static const struct of_device_id pps_gpio_dt_ids[] = {
193 { .compatible = "pps-gpio", },
194 { /* sentinel */ }
195};
196MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids);
197
198static struct platform_driver pps_gpio_driver = {
199 .probe = pps_gpio_probe,
200 .remove = pps_gpio_remove,
201 .driver = {
202 .name = PPS_GPIO_NAME,
203 .owner = THIS_MODULE,
204 .of_match_table = pps_gpio_dt_ids,
205 },
206};
207
208module_platform_driver(pps_gpio_driver);
209MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
210MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
211MODULE_DESCRIPTION("Use GPIO pin as PPS source");
212MODULE_LICENSE("GPL");
213MODULE_VERSION("1.0.0");