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 | |
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: &ts); |
52 | |
53 | info = data; |
54 | |
55 | rising_edge = gpiod_get_value(desc: info->gpio_pin); |
56 | if ((rising_edge && !info->assert_falling_edge) || |
57 | (!rising_edge && info->assert_falling_edge)) |
58 | pps_event(pps: info->pps, ts: &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(pps: info->pps, ts: &ts, PPS_CAPTURECLEAR, data); |
63 | |
64 | return IRQ_HANDLED; |
65 | } |
66 | |
67 | /* This function will only be called when an ECHO GPIO is defined */ |
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(desc: info->echo_pin, value: 1); |
77 | break; |
78 | |
79 | case PPS_CAPTURECLEAR: |
80 | if (pps->params.mode & PPS_ECHOCLEAR) |
81 | gpiod_set_value(desc: info->echo_pin, value: 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(timer: &info->echo_timer); |
89 | } |
90 | } |
91 | |
92 | /* Timer callback to reset the echo pin to the inactive state */ |
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(desc: info->echo_pin, value: 0); |
100 | } |
101 | |
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, flags: GPIOD_IN); |
109 | if (IS_ERR(ptr: data->gpio_pin)) |
110 | return dev_err_probe(dev, err: PTR_ERR(ptr: data->gpio_pin), |
111 | fmt: "failed to request PPS GPIO\n" ); |
112 | |
113 | data->assert_falling_edge = |
114 | device_property_read_bool(dev, propname: "assert-falling-edge" ); |
115 | |
116 | data->echo_pin = devm_gpiod_get_optional(dev, con_id: "echo" , flags: GPIOD_OUT_LOW); |
117 | if (IS_ERR(ptr: data->echo_pin)) |
118 | return dev_err_probe(dev, err: PTR_ERR(ptr: data->echo_pin), |
119 | fmt: "failed to request ECHO GPIO\n" ); |
120 | |
121 | if (!data->echo_pin) |
122 | return 0; |
123 | |
124 | ret = device_property_read_u32(dev, propname: "echo-active-ms" , val: &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 |
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 | |
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, size: 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(desc: 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(buf: data->info.name, PPS_MAX_NAME_LEN - 1, fmt: "%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(m: 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(info: &data->info, default_params: pps_default_params); |
202 | if (IS_ERR(ptr: data->pps)) { |
203 | dev_err(dev, "failed to register IRQ %d as PPS source\n" , |
204 | data->irq); |
205 | return PTR_ERR(ptr: data->pps); |
206 | } |
207 | |
208 | /* register IRQ interrupt handler */ |
209 | ret = devm_request_irq(dev, irq: data->irq, handler: pps_gpio_irq_handler, |
210 | irqflags: get_irqf_trigger_flags(data), devname: data->info.name, dev_id: data); |
211 | if (ret) { |
212 | pps_unregister_source(pps: 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 | |
223 | static 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(pps: data->pps); |
228 | del_timer_sync(timer: &data->echo_timer); |
229 | /* reset echo pin in any case */ |
230 | gpiod_set_value(desc: data->echo_pin, value: 0); |
231 | dev_info(&pdev->dev, "removed IRQ %d as PPS source\n" , data->irq); |
232 | return 0; |
233 | } |
234 | |
235 | static const struct of_device_id pps_gpio_dt_ids[] = { |
236 | { .compatible = "pps-gpio" , }, |
237 | { /* sentinel */ } |
238 | }; |
239 | MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids); |
240 | |
241 | static 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 | |
250 | module_platform_driver(pps_gpio_driver); |
251 | MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>" ); |
252 | MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>" ); |
253 | MODULE_DESCRIPTION("Use GPIO pin as PPS source" ); |
254 | MODULE_LICENSE("GPL" ); |
255 | MODULE_VERSION("1.2.0" ); |
256 | |