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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");
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/module.h>
16#include <linux/platform_device.h>
17#include <linux/slab.h>
18#include <linux/pps_kernel.h>
19#include <linux/pps-gpio.h>
20#include <linux/gpio/consumer.h>
21#include <linux/list.h>
22#include <linux/of_device.h>
23#include <linux/of_gpio.h>
24#include <linux/timer.h>
25#include <linux/jiffies.h>
26
27/* Info for each registered platform device */
28struct pps_gpio_device_data {
29 int irq; /* IRQ used as PPS source */
30 struct pps_device *pps; /* PPS source device */
31 struct pps_source_info info; /* PPS source information */
32 struct gpio_desc *gpio_pin; /* GPIO port descriptors */
33 struct gpio_desc *echo_pin;
34 struct timer_list echo_timer; /* timer to reset echo active state */
35 bool assert_falling_edge;
36 bool capture_clear;
37 unsigned int echo_active_ms; /* PPS echo active duration */
38 unsigned long echo_timeout; /* timer timeout value in jiffies */
39};
40
41/*
42 * Report the PPS event
43 */
44
45static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
46{
47 const struct pps_gpio_device_data *info;
48 struct pps_event_time ts;
49 int rising_edge;
50
51 /* Get the time stamp first */
52 pps_get_ts(&ts);
53
54 info = data;
55
56 rising_edge = gpiod_get_value(info->gpio_pin);
57 if ((rising_edge && !info->assert_falling_edge) ||
58 (!rising_edge && info->assert_falling_edge))
59 pps_event(info->pps, &ts, PPS_CAPTUREASSERT, data);
60 else if (info->capture_clear &&
61 ((rising_edge && info->assert_falling_edge) ||
62 (!rising_edge && !info->assert_falling_edge)))
63 pps_event(info->pps, &ts, PPS_CAPTURECLEAR, data);
64
65 return IRQ_HANDLED;
66}
67
68/* This function will only be called when an ECHO GPIO is defined */
69static void pps_gpio_echo(struct pps_device *pps, int event, void *data)
70{
71 /* add_timer() needs to write into info->echo_timer */
72 struct pps_gpio_device_data *info = data;
73
74 switch (event) {
75 case PPS_CAPTUREASSERT:
76 if (pps->params.mode & PPS_ECHOASSERT)
77 gpiod_set_value(info->echo_pin, 1);
78 break;
79
80 case PPS_CAPTURECLEAR:
81 if (pps->params.mode & PPS_ECHOCLEAR)
82 gpiod_set_value(info->echo_pin, 1);
83 break;
84 }
85
86 /* fire the timer */
87 if (info->pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) {
88 info->echo_timer.expires = jiffies + info->echo_timeout;
89 add_timer(&info->echo_timer);
90 }
91}
92
93/* Timer callback to reset the echo pin to the inactive state */
94static void pps_gpio_echo_timer_callback(struct timer_list *t)
95{
96 const struct pps_gpio_device_data *info;
97
98 info = from_timer(info, t, echo_timer);
99
100 gpiod_set_value(info->echo_pin, 0);
101}
102
103static int pps_gpio_setup(struct platform_device *pdev)
104{
105 struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
106 struct device_node *np = pdev->dev.of_node;
107 int ret;
108 u32 value;
109
110 data->gpio_pin = devm_gpiod_get(&pdev->dev,
111 NULL, /* request "gpios" */
112 GPIOD_IN);
113 if (IS_ERR(data->gpio_pin)) {
114 dev_err(&pdev->dev,
115 "failed to request PPS GPIO\n");
116 return PTR_ERR(data->gpio_pin);
117 }
118
119 data->echo_pin = devm_gpiod_get_optional(&pdev->dev,
120 "echo",
121 GPIOD_OUT_LOW);
122 if (data->echo_pin) {
123 if (IS_ERR(data->echo_pin)) {
124 dev_err(&pdev->dev, "failed to request ECHO GPIO\n");
125 return PTR_ERR(data->echo_pin);
126 }
127
128 ret = of_property_read_u32(np,
129 "echo-active-ms",
130 &value);
131 if (ret) {
132 dev_err(&pdev->dev,
133 "failed to get echo-active-ms from OF\n");
134 return ret;
135 }
136 data->echo_active_ms = value;
137 /* sanity check on echo_active_ms */
138 if (!data->echo_active_ms || data->echo_active_ms > 999) {
139 dev_err(&pdev->dev,
140 "echo-active-ms: %u - bad value from OF\n",
141 data->echo_active_ms);
142 return -EINVAL;
143 }
144 }
145
146 if (of_property_read_bool(np, "assert-falling-edge"))
147 data->assert_falling_edge = true;
148 return 0;
149}
150
151static unsigned long
152get_irqf_trigger_flags(const struct pps_gpio_device_data *data)
153{
154 unsigned long flags = data->assert_falling_edge ?
155 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
156
157 if (data->capture_clear) {
158 flags |= ((flags & IRQF_TRIGGER_RISING) ?
159 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING);
160 }
161
162 return flags;
163}
164
165static int pps_gpio_probe(struct platform_device *pdev)
166{
167 struct pps_gpio_device_data *data;
168 int ret;
169 int pps_default_params;
170 const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data;
171
172 /* allocate space for device info */
173 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
174 if (!data)
175 return -ENOMEM;
176 platform_set_drvdata(pdev, data);
177
178 /* GPIO setup */
179 if (pdata) {
180 data->gpio_pin = pdata->gpio_pin;
181 data->echo_pin = pdata->echo_pin;
182
183 data->assert_falling_edge = pdata->assert_falling_edge;
184 data->capture_clear = pdata->capture_clear;
185 data->echo_active_ms = pdata->echo_active_ms;
186 } else {
187 ret = pps_gpio_setup(pdev);
188 if (ret)
189 return -EINVAL;
190 }
191
192 /* IRQ setup */
193 ret = gpiod_to_irq(data->gpio_pin);
194 if (ret < 0) {
195 dev_err(&pdev->dev, "failed to map GPIO to IRQ: %d\n", ret);
196 return -EINVAL;
197 }
198 data->irq = ret;
199
200 /* initialize PPS specific parts of the bookkeeping data structure. */
201 data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT |
202 PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC;
203 if (data->capture_clear)
204 data->info.mode |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR |
205 PPS_ECHOCLEAR;
206 data->info.owner = THIS_MODULE;
207 snprintf(data->info.name, PPS_MAX_NAME_LEN - 1, "%s.%d",
208 pdev->name, pdev->id);
209 if (data->echo_pin) {
210 data->info.echo = pps_gpio_echo;
211 data->echo_timeout = msecs_to_jiffies(data->echo_active_ms);
212 timer_setup(&data->echo_timer, pps_gpio_echo_timer_callback, 0);
213 }
214
215 /* register PPS source */
216 pps_default_params = PPS_CAPTUREASSERT | PPS_OFFSETASSERT;
217 if (data->capture_clear)
218 pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR;
219 data->pps = pps_register_source(&data->info, pps_default_params);
220 if (IS_ERR(data->pps)) {
221 dev_err(&pdev->dev, "failed to register IRQ %d as PPS source\n",
222 data->irq);
223 return PTR_ERR(data->pps);
224 }
225
226 /* register IRQ interrupt handler */
227 ret = devm_request_irq(&pdev->dev, data->irq, pps_gpio_irq_handler,
228 get_irqf_trigger_flags(data), data->info.name, data);
229 if (ret) {
230 pps_unregister_source(data->pps);
231 dev_err(&pdev->dev, "failed to acquire IRQ %d\n", data->irq);
232 return -EINVAL;
233 }
234
235 dev_info(data->pps->dev, "Registered IRQ %d as PPS source\n",
236 data->irq);
237
238 return 0;
239}
240
241static int pps_gpio_remove(struct platform_device *pdev)
242{
243 struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
244
245 pps_unregister_source(data->pps);
246 if (data->echo_pin) {
247 del_timer_sync(&data->echo_timer);
248 /* reset echo pin in any case */
249 gpiod_set_value(data->echo_pin, 0);
250 }
251 dev_info(&pdev->dev, "removed IRQ %d as PPS source\n", data->irq);
252 return 0;
253}
254
255static const struct of_device_id pps_gpio_dt_ids[] = {
256 { .compatible = "pps-gpio", },
257 { /* sentinel */ }
258};
259MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids);
260
261static struct platform_driver pps_gpio_driver = {
262 .probe = pps_gpio_probe,
263 .remove = pps_gpio_remove,
264 .driver = {
265 .name = PPS_GPIO_NAME,
266 .of_match_table = pps_gpio_dt_ids,
267 },
268};
269
270module_platform_driver(pps_gpio_driver);
271MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
272MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
273MODULE_DESCRIPTION("Use GPIO pin as PPS source");
274MODULE_LICENSE("GPL");
275MODULE_VERSION("1.2.0");