255 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * pps-gpio.c -- PPS client driver using GPIO4 *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 ": " fmt11 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 event42 */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 long142get_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 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 234static const struct of_device_id pps_gpio_dt_ids[] = {235 { .compatible = "pps-gpio", },236 { /* sentinel */ }237};238MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids);239 240static struct platform_driver pps_gpio_driver = {241 .probe = pps_gpio_probe,242 .remove_new = pps_gpio_remove,243 .driver = {244 .name = PPS_GPIO_NAME,245 .of_match_table = pps_gpio_dt_ids,246 },247};248 249module_platform_driver(pps_gpio_driver);250MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");251MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");252MODULE_DESCRIPTION("Use GPIO pin as PPS source");253MODULE_LICENSE("GPL");254MODULE_VERSION("1.2.0");255