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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* pps-gpio.c -- PPS client driver using GPIO
*
* Copyright (C) 2010 Ricardo Martins <rasm@fe.up.pt>
* Copyright (C) 2011 James Nuss <jamesnuss@nanometrics.ca>
*/
#define PPS_GPIO_NAME "pps-gpio"
#define pr_fmt(fmt) PPS_GPIO_NAME ": " fmt
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/pps_kernel.h>
#include <linux/gpio/consumer.h>
#include <linux/list.h>
#include <linux/property.h>
#include <linux/timer.h>
#include <linux/jiffies.h>
/* Info for each registered platform device */
struct pps_gpio_device_data {
int irq; /* IRQ used as PPS source */
struct pps_device *pps; /* PPS source device */
struct pps_source_info info; /* PPS source information */
struct gpio_desc *gpio_pin; /* GPIO port descriptors */
struct gpio_desc *echo_pin;
struct timer_list echo_timer; /* timer to reset echo active state */
bool assert_falling_edge;
bool capture_clear;
unsigned int echo_active_ms; /* PPS echo active duration */
unsigned long echo_timeout; /* timer timeout value in jiffies */
};
/*
* Report the PPS event
*/
static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
{
const struct pps_gpio_device_data *info;
struct pps_event_time ts;
int rising_edge;
/* Get the time stamp first */
pps_get_ts(&ts);
info = data;
rising_edge = gpiod_get_value(info->gpio_pin);
if ((rising_edge && !info->assert_falling_edge) ||
(!rising_edge && info->assert_falling_edge))
pps_event(info->pps, &ts, PPS_CAPTUREASSERT, data);
else if (info->capture_clear &&
((rising_edge && info->assert_falling_edge) ||
(!rising_edge && !info->assert_falling_edge)))
pps_event(info->pps, &ts, PPS_CAPTURECLEAR, data);
return IRQ_HANDLED;
}
/* This function will only be called when an ECHO GPIO is defined */
static void pps_gpio_echo(struct pps_device *pps, int event, void *data)
{
/* add_timer() needs to write into info->echo_timer */
struct pps_gpio_device_data *info = data;
switch (event) {
case PPS_CAPTUREASSERT:
if (pps->params.mode & PPS_ECHOASSERT)
gpiod_set_value(info->echo_pin, 1);
break;
case PPS_CAPTURECLEAR:
if (pps->params.mode & PPS_ECHOCLEAR)
gpiod_set_value(info->echo_pin, 1);
break;
}
/* fire the timer */
if (info->pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) {
info->echo_timer.expires = jiffies + info->echo_timeout;
add_timer(&info->echo_timer);
}
}
/* Timer callback to reset the echo pin to the inactive state */
static void pps_gpio_echo_timer_callback(struct timer_list *t)
{
const struct pps_gpio_device_data *info;
info = from_timer(info, t, echo_timer);
gpiod_set_value(info->echo_pin, 0);
}
static int pps_gpio_setup(struct device *dev)
{
struct pps_gpio_device_data *data = dev_get_drvdata(dev);
int ret;
u32 value;
data->gpio_pin = devm_gpiod_get(dev, NULL, GPIOD_IN);
if (IS_ERR(data->gpio_pin))
return dev_err_probe(dev, PTR_ERR(data->gpio_pin),
"failed to request PPS GPIO\n");
data->echo_pin = devm_gpiod_get_optional(dev, "echo", GPIOD_OUT_LOW);
if (IS_ERR(data->echo_pin))
return dev_err_probe(dev, PTR_ERR(data->echo_pin),
"failed to request ECHO GPIO\n");
if (data->echo_pin) {
ret = device_property_read_u32(dev, "echo-active-ms", &value);
if (ret) {
dev_err(dev, "failed to get echo-active-ms from FW\n");
return ret;
}
data->echo_active_ms = value;
/* sanity check on echo_active_ms */
if (!data->echo_active_ms || data->echo_active_ms > 999) {
dev_err(dev, "echo-active-ms: %u - bad value from FW\n",
data->echo_active_ms);
return -EINVAL;
}
}
data->assert_falling_edge =
device_property_read_bool(dev, "assert-falling-edge");
return 0;
}
static unsigned long
get_irqf_trigger_flags(const struct pps_gpio_device_data *data)
{
unsigned long flags = data->assert_falling_edge ?
IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
if (data->capture_clear) {
flags |= ((flags & IRQF_TRIGGER_RISING) ?
IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING);
}
return flags;
}
static int pps_gpio_probe(struct platform_device *pdev)
{
struct pps_gpio_device_data *data;
struct device *dev = &pdev->dev;
int ret;
int pps_default_params;
/* allocate space for device info */
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
dev_set_drvdata(dev, data);
/* GPIO setup */
ret = pps_gpio_setup(dev);
if (ret)
return -EINVAL;
/* IRQ setup */
ret = gpiod_to_irq(data->gpio_pin);
if (ret < 0) {
dev_err(dev, "failed to map GPIO to IRQ: %d\n", ret);
return -EINVAL;
}
data->irq = ret;
/* initialize PPS specific parts of the bookkeeping data structure. */
data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT |
PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC;
if (data->capture_clear)
data->info.mode |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR |
PPS_ECHOCLEAR;
data->info.owner = THIS_MODULE;
snprintf(data->info.name, PPS_MAX_NAME_LEN - 1, "%s.%d",
pdev->name, pdev->id);
if (data->echo_pin) {
data->info.echo = pps_gpio_echo;
data->echo_timeout = msecs_to_jiffies(data->echo_active_ms);
timer_setup(&data->echo_timer, pps_gpio_echo_timer_callback, 0);
}
/* register PPS source */
pps_default_params = PPS_CAPTUREASSERT | PPS_OFFSETASSERT;
if (data->capture_clear)
pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR;
data->pps = pps_register_source(&data->info, pps_default_params);
if (IS_ERR(data->pps)) {
dev_err(dev, "failed to register IRQ %d as PPS source\n",
data->irq);
return PTR_ERR(data->pps);
}
/* register IRQ interrupt handler */
ret = devm_request_irq(dev, data->irq, pps_gpio_irq_handler,
get_irqf_trigger_flags(data), data->info.name, data);
if (ret) {
pps_unregister_source(data->pps);
dev_err(dev, "failed to acquire IRQ %d\n", data->irq);
return -EINVAL;
}
dev_info(data->pps->dev, "Registered IRQ %d as PPS source\n",
data->irq);
return 0;
}
static int pps_gpio_remove(struct platform_device *pdev)
{
struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
pps_unregister_source(data->pps);
del_timer_sync(&data->echo_timer);
/* reset echo pin in any case */
gpiod_set_value(data->echo_pin, 0);
dev_info(&pdev->dev, "removed IRQ %d as PPS source\n", data->irq);
return 0;
}
static const struct of_device_id pps_gpio_dt_ids[] = {
{ .compatible = "pps-gpio", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids);
static struct platform_driver pps_gpio_driver = {
.probe = pps_gpio_probe,
.remove = pps_gpio_remove,
.driver = {
.name = PPS_GPIO_NAME,
.of_match_table = pps_gpio_dt_ids,
},
};
module_platform_driver(pps_gpio_driver);
MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
MODULE_DESCRIPTION("Use GPIO pin as PPS source");
MODULE_LICENSE("GPL");
MODULE_VERSION("1.2.0");
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